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Martin, Michaël. "Mécanisme moléculaire de l'antagonisme du complexe HUSH par les protéines lentivirales Vpx et Vpr." Electronic Thesis or Diss., Université Paris Cité, 2021. http://www.theses.fr/2021UNIP5160.
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Les VIH-1 et VIH-2, lentivirus responsables du SIDA, sont issus de transmissions inter-espèces de virus simiens (SIV) à l'homme. Outre leurs protéines de structure et de régulation, les lentivirus codent pour des protéines auxiliaires qui favorisent la réplication virale dans la cellule hôte en contrecarrant des facteurs cellulaires antiviraux, appelés facteurs de restriction. Le mécanisme d'action de ces protéines virales auxiliaires repose souvent sur le détournement de complexes Ubiquitine-Ligases, un mécanisme très répandu chez une grande variété de pathogènes, en vue de dégrader des protéines de la cellule hôte. Ce mécanisme est utilisé par la protéine Vpx, exprimée uniquement par VIH-2 (et non par VIH-1), qui induit la dégradation de SAMDH1, un facteur de restriction bloquant l'étape de transcription inverse. Ainsi, Vpx fait un pont moléculaire entre l'adaptateur DCAF1 du complexe Ubiquitine-Ligase Cul4A-DDB1(DCAF1) et SAMHD1, ce qui entraîne l'ubiquitination et la dégradation de SAMHD1. En 2018, notre équipe a montré que Vpx induisait la dégradation d'un facteur cellulaire supplémentaire : le complexe HUSH, composé de TASOR, MPP8 et Périphiline. Ce complexe intervient dans la répression épigénétique non seulement de nombreux gènes cellulaires, d'éléments rétro-transposables et de rétrovirus endogènes, mais aussi du génome du VIH intégré dans celui de la cellule infectée. En dégradant HUSH, Vpx favorise l'expression virale. Dans ce contexte, les objectifs de ma thèse ont été de : (i) Déterminer si le mécanisme de dégradation de HUSH induit par Vpx de VIH2 était identique au mécanisme de dégradation de SAMHD1. J'ai pu mettre en évidence des différences importantes entre les deux mécanismes bien que Vpx utilise, dans les deux cas, le même adaptateur d'Ubiquitine-Ligase, DCAF1 (coeur principal du travail de thèse, article soumis). (ii) Caractériser les déterminants moléculaires en jeu dans l'antagonisme de HUSH par d'autres protéines lentivirales. Premièrement, il s'agissait de savoir si les différentes protéines virales apparentées à Vpx chez différentes espèces de virus simiens avaient toutes la même capacité à dégrader le complexe HUSH. Nous avons ainsi pu mettre en évidence une spécificité lentivirale de l'antagonisme du complexe HUSH, une caractéristique majeure des facteurs de restriction (contribution à l'article Chougui et al., Nature microbiology, 2018). Dans un second temps, ceci m'a conduit à débuter l'étude des déterminants viraux de ces protéines apparentées à Vpx, telles les protéines Vpr de différentes souches de SIVagm (infectant le singe vert africain) qui présentent des phénotypes différents quant à la dégradation de SAMHD1 ou de HUSH (travail en cours). L'ensemble des résultats a permis, d'une part de mieux caractériser le mécanisme d'antagonisme de HUSH par les protéines lentivirales Vpx/Vpr, et d'autre part de fournir de premiers outils moléculaires pour différencier l'antagonisme de HUSH de celui de SAMHD1 dans les cellules primaires. Dans le futur, les données pourront aider à mieux comprendre comment diverses protéines lentivirales se sont adaptées à leurs différents substrats cellulaires (et vice-versa) au cours de l'évolution. Enfin, cibler HUSH grâce à l'identification de déterminant d'interaction ou de dégradation pourrait être intéressant pour le développement de nouvelles cibles thérapeutiques<br>HIV-1 and HIV-2, lentiviruses responsible for AIDS, appeared in humans after cross-species transmissions from simian viruses (SIV). In addition to their structural and regulatory proteins, lentiviruses encode auxiliary proteins that promote viral replication in the host cell by counteracting antiviral cellular factors, called restriction factors. The mechanism of action of these viral auxiliary proteins often relies on the hijacking of Ubiquitin-Ligase complexes, a mechanism widely used by various pathogens, to degrade host cell proteins. This mechanism is used by the Vpx protein, expressed only by HIV-2 (and not by HIV-1), which induces the degradation of SAMDH1, a restriction factor blocking the reverse transcription step. Thus, Vpx molecularly bridges the DCAF1 adaptor of the Cul4A-DDB1(DCAF1) Ubiquitin-Ligase complex with SAMHD1, resulting in ubiquitination and degradation of SAMHD1. In 2018, our team showed that Vpx induces the degradation of an additional cellular factor: the HUSH complex, composed of TASOR, MPP8 and Periphilin. This complex is involved in the epigenetic repression not only of many cellular genes, retro-transposable elements and endogenous retroviruses, but also of the HIV genome integrated into the infected cell. By degrading HUSH, Vpx promotes viral expression. In this context, the objectives of my thesis were to: (i) Determine whether HUSH degradation mechanism induced by HIV-2 Vpx was identical to SAMHD1 degradation mechanism. I was able to highlight important differences between the two mechanisms although Vpx uses, in both cases, the same Ubiquitin-Ligase adaptor, DCAF1 (main focus of the thesis work, submitted article). (ii) Characterize the molecular determinants involved in the antagonism of HUSH by other lentiviral proteins. First, we wanted to know if different Vpx-related viral proteins, in various simian virus species, had the same capacity to degrade the HUSH complex. This allowed us to reveal a lentiviral species-specificity of HUSH complex antagonism, a major characteristic of restriction factors (contribution to Chougui et al., Nature microbiology, 2018). Secondly, this led me to start studying the viral determinants of these Vpx-related proteins, such as the Vpr proteins from different strains of SIVagm (infecting the African green monkey) that present different phenotypes regarding both SAMHD1 or HUSH degradation (work in progress). All the results allowed us to better characterize the mechanism of HUSH antagonism by Vpx/Vpr lentiviral proteins, and to provide the first molecular tools to differentiate HUSH antagonism from SAMHD1 antagonism in primary cells. In the future, these data may help to better understand how various lentiviral proteins have adapted to their different cellular substrates (and vice versa) along evolution. Finally, targeting HUSH through the identification of interaction or degradation determinants could be interesting for the development of new therapeutic targets
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Hani, Lylia. "Caractérisation et rôle des lymphocytes T CD4+ mémoires SAMHD1low au cours de l'infection par le VIH-1." Thesis, Paris Est, 2018. http://www.theses.fr/2018PESC0087/document.
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La mise en évidence du rôle de la molécule SAMHD1 dans l’infection par le VIH-1 en tant que facteur de restriction a ouvert de nouvelles perspectives dans la compréhension de la pathogénicité du virus.En effet, il a été clairement démontré que dans les cellules myéloïdes comme les monocytes/macrophages et les cellules dendritiques ainsi que les lymphocytes T CD4+ quiescents, SAMHD1 jouait un rôle important dans la protection de ces cellules de l’infection. En revanche, le rôle de cette molécule dans l’infection des lymphocytes activés, qui sont souvent la cible préférentielle du virus, n’est pas élucidé.Nos résultats ont révélé l'existence d'une sous-population de lymphocytes T CD4+ mémoires exprimant de faibles niveaux de SAMHD1 (CD4+ CD45RO+ SAMHD1low), tandis que la grande majorité des lymphocytes expriment cette molécule à des niveaux plus élevés (94±0.7%). Nous montrons également que ces cellules sont hautement différenciées, qu’elles expriment en larges proportions le marqueur de cycle cellulaire Ki67 et qu’elles sont enrichies en cellules « T helper 17 » (Th17) dans le sang périphérique.De plus, la fréquence de la population CD4+ CD45RO+ SAMHD1low, est diminuée de manière significative chez les patients infectés par le VIH-1 par rapport aux sujets sains. De manière intéressante, nous montrons que dans les ganglions, les cellules T follicular helper (Tfh) expriment faiblement SAMHD1 et sont plus susceptibles à l’infection par le VIH-1 in vitro.L’ensemble de ces résultats suggère que les cellules SAMHD1 low représentent une cible préférentielle pour le virus et pourraient contribuer au réservoir viral.Les objectifs de ce projet sont:1. Déterminer si les cellules SAMHD1low contiennent plus de virus par comparaison aux cellules mémoires SAMHD1high et comparer les séquences virales isolées des cellules mémoires SAMHD1low et SAMHD1high.2. Caractérisation des cellules SAMHD1low au niveau moléculaire par une analyse transcriptomique qui permettra la mise en évidence de marqueurs membranaires<br>We have previously reported the presence of memory CD4+ T cells that display low levels of SAMHD1 (SAMHD1low ) enriched in Th17 and Tfh cells. Here we investigated gene expression profile and the size and composition of HIV DNA population in SAMHD1 low cells.A total of 36 individuals on c-ART (median: 7y) with median CD4+ counts and nadir of 549 cells/ul and 210 cells/ul respectively, including 6 elite controllers (EC, CD4+: 900 cells/ul) and 8 healthy donors were studied. Blood memory CD4+ CD45RO+ SAMHD1low, CD45RO+ SAMHD1high and naive CD45RO- SAMHD1high cells were sorted. Cell associated HIV-1 DNA levels were quantified (HIV DNA Cell, Biocentric) and ultra-deep-sequencing (UDS, 454/Roche) of partial env (C2/V3) HIV-1 DNA was performed. Gene expression profile on sorted cells was deternined with RNA-Sequencing (Illumina RNASeq technology). Levels of HIV-1 DNA were significantly higher in memory SAMHD1low cells compared to SAMHD1high cells (4.5 [3.1-6.2] vs 3.8 [2.9-5.7] log/10 6 cells, respectively, p=0.02) among c-ART individuals, while naïve CD45RO- SAMHD1high showed lower levels (3.1 [1.6-4.4]). EC exhibited low HIV-1 DNA level in both SAMHD1low and SAMHD1high (1.6 and 2.3 log/10 6 cells respectively p>0.05). Naïve CD45RO - SAMHD1 high cells from EC showed lower DNA compared to naïve cells from c-ART pts (1.6 and 3.1 log/10 6 cells, respectively, p=0.01). Phylogenetic analyses revealed well-segregated HIV-DNA populations between subsets with significant compartmentalization between SAMHD1low and SAMHD1high cells in all but 2 participants (p<0.001) and limited viral exchange. Moreover SAMHD1low cells exhibited a distinct gene profile as compared to SAMHD1high allowing thus further characterisation of these cells.This pilot study revealed distinct HIV DNA populations in size and composition associated with unique genes profile in memory SAMHD1low cells. We show that memory SAMHD1low cells exhibit distinct genes profile which segregates them from the SAMHD1 high counterpart, and contain the highest level of HIV-1 DNA. We reveal distinct/well-segregated HIV-1 DNA populations in both subsets, suggesting minimal viral exchange
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Valverde, Estrella Lorena. "TREX1 and SAMHD1, and Aicardi-Goutières Syndrome." Doctoral thesis, Universitat de Barcelona, 2015. http://hdl.handle.net/10803/291940.
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Aicardi-Goutières Syndrome (AGS) is a rare encephalopathy which mimics a viral intrauterine infection and is characterized by calcifications of the basal ganglia, cerebral atrophy and IFN-a in the cerebrospinal fluid. AGS is a heterogenic disease associated with mutations in the gene of the exonuclease TREX1, in any of the genes codifying for the ribonuclease H2, in the phosphohydrolase SAMHD1, in the deaminase ADAR1 or in the cytoplasmic sensor MDA5. The knowledge of these functions is basic for the comprehension of the beginning of the pathogenesis of AGS. In this thesis we focused in the mechanism of Samhd1 transcription. We have seen that Samhd1 is induced by pro-inflammatory stimuli but neither by anti-inflammatory stimuli nor TNF-a, and that the induction of Samhd1 is through STAT1 pathway. We wanted to know a bit more about Samhd1 induction so we focused on the study of its promoter. We did a construct in a luciferase-reporter vector with 1500bp of Samhd1 promoter, and we saw that this region of the promoter is enough to induce luciferase expression. From this construct, we did new plasmids and when deleting a specific region, the luciferase expression was abolished, indicating that in Samhd1 promoter, 161bp are critical for Samhd1 induction. EMSA assays showed that Samhd1 expression is repressed in basal conditions by an unknown protein, and ChIP assays also showed that IRF1 is involved in Samhd1 induction by IFN-.. We hypothesized that the regulation mechanism is depending in an STAT1-depending pathway, through IRF1, and also in an STAT1-independing pathway, through an unknown mechanism up to date. We checked with proteomics analysis the protein which might be involved in Samhd1 repression but the results were not significant. We also constructed a conditional KO mouse for TREX1, and now we are crossing it with different CRESocs2 expressing strands. Homozygous KO expressing CRElitter, show a similar phenotype to TREX1 total KO. We are in the process to obtain homozygous KO expressing CRELysM, but due to problems with the penetrance of this CRE allele we have some difficulties. All together, the results of this thesis will shed light in the inner operation of AGS.<br>La síndrome d'Aicardi-Goutières (AGS), és una malaltia autoimmunitària recessiva que mimetitza una infecció vírica intrauterina, i la qual és caracteritzada per calcificacions intracranials, atròfia cerebral i augment d'IFN-alfa al líquid cefaloraquidi. L'AGS és una malaltia genètica heterogènia associada amb mutacions al gen que codifica per a l'exonucleasa TREX1, a qualsevol dels gens codificants per a les components de la ribonucleasa RNASE H2, a la fosfohidrolasa SAMHD1, a la deaminasa ADAR1 o al sensor citoplasmàtic MDA5. El coneixement d'aquestes funcions és fonamental per tal d'entendre la patogènesi de l'AGS. En aquesta tesi s'ha aprofundit en el coneixement del mecanisme regulador de la transcripció de Samhd1. Hem vist que Samhd1 es troba expressat en diferents òrgans sense necessitat de cap estímul previ, com el pàncrees, l’intestí prim i els macròfags derivats de moll d’os, i en diferents quantitats en altres òrgans de ratolí. Donada la important afectació que té l’AGS al cervell, també es va analitzar la seva expressió en neurones i cèl·lules de la micròglia. També hem vist que Samhd1 es troba induït en presència de citocines proinflamatòries, però no es troba afectada la seva expressió en presència de citocines antiinflamatòries així com tampoc en presència de TNF-gamma. Utilitzant macròfags derivats de ratolins deficients en STAT1, hem pogut demostrar que l’expressió de Samhd1 per IFN-alfa és a través d’STAT1, ja que la seva expressió es troba completament reprimida en aquestes cèl·lules. Ens vam centrar en la inducció de Samhd1 i per la seva comprensió vam focalitzar en l’estudi del seu promotor. Es van clonar 1500 parells de bases del promotor de Samhd1 en un plasmidi reporter de luciferasa, i es va veure que aquest fragment era suficient per induir l’expressió de luciferasa. A partir d’aquest constructe, es van realitzar llavors noves construccions delecionant cada vegada una regió del promotor. Es va veure que en delecionar una regió específica de 161pb, l’expressió de luciferasa es trobava completament reprimida, indicant que aquesta regió del promotor és crítica per a la inducció de Samhd1. Experiments de retard en gel (EMSA) van mostrar que Samhd1 es troba reprimit en condicions basals per una proteïna que no hem arribat a caracteritzar, i experiments de precipitació de cromatina (ChIP) van mostrar que IRF1 es troba involucrada en la inducció de Samhd1 per IFN-alfa. La nostra hipòtesi doncs, és que l’expressió de Samhd1 té un mecanisme de regulació doble: en condicions basals es troba reprimit i en presència d’IFN-alfa s’indueix una via de senyalització independent d’STAT1 que fa saltar el complex repressor del promotor, i també s’indueix una via de senyalització dependent d’STAT1, que indueix l’expressió d’IRF1 i que activa la transducció de Samhd1. Fins ara no hem caracteritzat la proteïna o complex de proteïnes que reprimeix l’expressió de Samhd1 en condicions basals, però s’està investigant mitjançant anàlisis proteòmics. En aquesta tesi també s’ha fet la construcció d’un ratolí KO condicional per a TREX1. Una vegada aconseguit aquest animal condicional, el qual conté el gen de Trex1 flanquejat per dues dianes LoxP, aquest s’està encreuant amb diferents soques que expressen CRE sota regulació de diferents Socs2 promotors. Els ratolins homozigots KO i que expressen CRE, tenen un fenotip similar al fenotip que mostren els ratolins KO totals de TREX1. Estem en el procés d’obtenció de ratolins homozigots KO i que expressen CRELysM però, donat a problemes amb la penetrància d’aquest al·lel, hem tingut algunes dificultats. Els resultats d’aquesta tesi en conjunt poden ajudar a entendre una mica més el funcionament de l'AGS.
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Antonucci, Jenna Marie. "Mechanisms of HIV-1 Restriction by the Host Protein SAMHD1." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1524006072232491.
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Sébert, Marie. "Génétique et évolution clonale des syndromes d’insuffisance médullaire." Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCC271.
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Les syndromes d’insuffisance médullaire sont liés à des mutations constitutionnelles à l’origine d’une hématopoïèse déficiente chez les patients atteints. Ils représentent un groupe hétérogène de maladies syndromiques, et impliquent plusieurs familles de gènes avec des mécanismes biologiques différents conduisant à l’insuffisance médullaire. Ces maladies prédisposent à une évolution clonale somatique, avec un risque accru de développer un syndrome myélodysplasique (SMD) ou une leucémie aigüe myéloïde (LAM) au cours du temps. Nous avons séquencé et analysé l’exome d’ADN fibroblastique d’une cohorte de 179 patients ayant des insuffisances médullaires, des SMD ou des LAM, supposés d’origine constitutionnelle mais sans diagnostic établi. Ce travail a permis de porter un diagnostic moléculaire chez 86 (48%) patients, et de participer à la description de nouveaux syndromes impliquant les gènes SAMD9/SAMD9L (N=16/86, 18,6%), MECOM/EVI1 (N=6, 7%) et ERCC6L2 (N=7, 8,1%). Le suivi longitudinal des patients nous a permis de décrire un modèle d’évolution clonale particulier chez les patients ayant des mutations SAMD9/SAMD9L. Le syndrome d’insuffisance médullaire le plus fréquent est la maladie de Fanconi (AF ou FA), causée par une mutation germinale dans un des gènes de la voie de réparation FA/BRCA. Les cellules des patients FA ont une instabilité chromosomique liée à un défaut de réparation, avec une pression de sélection conduisant à une évolution clonale prototypique. Nous avons étudié une cohorte de 335 patients FA et confirmé de façon statistiquement significative l’ordre d’apparition des évènements cytogénétiques de ces patients au cours de l’évolution clonale et de la leucémogenèse : 1q+, 3q+, -7/del7q, délétion ou mutation RUNX1. L’étude moléculaire longitudinale des patients (NGS panel, WES, WGS) a confirmé un mécanisme oncogénique en rapport avec une instabilité chromosomique plus que génomique. En nous intéressant à l’anomalie cytogénétique la plus fréquente et la plus précoce : le 1q+, nous avons observé que le point de cassure péricentromérique sur ce chromosome correspondait à un site fragile, réparé ensuite par une voie de réparation alt NHEJ. La zone minimale dupliquée contenait le gène MDM4, un inhibiteur des fonctions transactivatrices de p53, qui constituait ainsi un bon candidat pour conférer aux cellules un avantage clonal et initier la leucémogenèse. Nous avons d’abord confirmé que les cellules des patients 1q+ avaient une surexpression de MDM4 et une inactivation de la voie p53 en aval (RNAseq). Puis, nous avons montré que cette surexpression permettait de restaurer les capacités fonctionnelles des progéniteurs hématopoïétiques humains FA, de façon réversible avec l’inhibition de MDM4, constituant ainsi une éventuelle cible thérapeutique. Les syndromes d’insuffisance médullaire sont des maladies rares, et nos travaux, en parallèle de ceux d’autres équipes, ont participé à la description de nouveaux gènes impliqués. L’étude de l’évolution clonale de ces syndromes représente une évolution dans la compréhension de la physiopathologie des SMD/LAM, et peut conduire à l’identification de cibles thérapeutiques chez ces patients<br>Inherited bone marrow failure (IBMF) syndromes are heterogeneous diseases related to germ line mutations causing deficient hematopoiesis in mutated patients. Mutations involve several families of genes with different biological pathways driving the bone marrow failure. Most germ line genetic BMF disorders are characterized by a high propensity to clonal evolution and to develop MDS or AML. We used a whole-exome sequencing (WES) comprehensive analysis on fibroblast DNA samples from 179 patients with BMF/MDS of unresolved inherited origin. We provided a molecular diagnosis for 86/179 BMF patients (48%) including several seldom-reported IBMF/MDS entities like SAMD9/SAMD9L, MECOM/EVI1, and ERCC6L2. In particular, we described a specific clonal evolution in patients having mutations in SAMD9 and SAMD9L.Fanconi anemia (FA) is the most common IBMF syndrome, caused by a germ line mutation in one gene of the FA pathway. DNA repair deficiency in patient’s FA cells leads to chromosomal instability, which sets the stage for clonal evolution with a specific pattern of chromosomal abnormalities. We used integrated clinical, next-generation genomic and functional studies on primary cells from a National cohort of 335 FA patients, including 98 with clonal evolution, to decipher the mechanisms of BM progression. While relatively few somatic point mutations were found, unbalanced translocations leading to gross chromosomal copy-number abnormalities were most prominent. Whole genome sequencing revealed an FA-specific signature in which microhomology-mediated end joining (MMEJ) or non homologous end joining (NHEJ) repair had mediated genome rearrangements, consistent with the constitutive homologous repair defect. Longitudinal studies confirmed the order of chromosomal events during FA patients oncogenesis: 1q+, 3q+, -7/del7q, del or RUNX1 mutations. A major initial step was duplication of chromosome 1q, resulting in strong expression of MDM4, a negative regulator of p53, which can be targeted by MDM4-inhibitors.IBMF are rare diseases and our study participated to describe new genetic and clinical entities. Studying the clonal evolution of IBMF syndromes can help to understand MDS and AML pathophysiology and lead to therapeutic target identification
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Louis, Tania. "Étude des fonctions cellulaires de SAMHD1, facteur de restriction du VIH-1." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS050/document.
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L'étude des interactions entre un pathogène et son hôte, bien qu'ayant généralement pour objectif de contrôler l'infection par le pathogène, permet parfois de découvrir des éléments fondamentaux sur le fonctionnement de l'hôte. J'ai choisi d'étudier les fonctions cellulaires d'une protéine initialement identifiée comme un facteur de restriction du VIH-1. SAMHD1 (SAM domain and HD domain-containing protein 1) est une protéine exprimée dans la plupart des tissus humains. Elle est capable d'hydrolyser les déoxyribonucléotides triphosphates (dNTP) cellulaires et possède une activité nucléase ciblant différents acides nucléiques dont les ARN simple brin in vitro. Des mutations dans le gène SAMHD1 entraînent le développement d'une maladie auto-immune pouvant conduire à la mort précoce des nourrissons, ce qui suggère un rôle de la protéine correspondante dans la régulation de la réponse immunitaire. Il a été montré que SAMHD1 est un facteur de restriction capable d'empêcher l'infection de cellules ne se divisant pas par le VIH-1. La protéine virale Vpx, exprimée par le VIH-2, est capable d'induire la dégradation de SAMHD1 par le protéasome et permet de rendre permissives les cellules initialement résistantes à l'infection par le VIH. SAMHD1 est en réalité capable de restreindre l'infection par des virus aussi différents que les rétrovirus et le virus de l'herpès simplex 1. Néanmoins, le mécanisme permettant à SAMHD1 de contrecarrer différents virus reste aujourd'hui sujet à controverse. Initialement considéré comme agissant en dégradant les dNTP cellulaires, SAMHD1 semble également capable de dégrader l'ARN génomique du VIH-1. Si de nombreux travaux portent sur l'activité antivirale de SAMHD1, peu de données sont disponibles concernant la fonction cellulaire de cette protéine. Or SAMHD1 est capable de réguler la quantité de dNTP cellulaires et d'interagir avec certains acides nucléiques. Ces données font de SAMHD1 un acteur potentiel de différents processus cellulaires fondamentaux sensibles à la quantité intracellulaire de dNTP, notamment la réplication du génome ou la réparation des dommages à l'ADN. J'ai montré au cours de mon doctorat que SAMHD1 module le cycle cellulaire et notamment que la surexpression de cette protéine ralentit la prolifération cellulaire. J'ai également observé que la surexpression de SAMHD1 augmente la sensibilité des cellules aux agents induisant des ruptures double brin de l'ADN. De plus, j'ai découvert qu'en cas de ruptures double brin de l'ADN cellulaire, SAMHD1 est régulé de façon spécifique par phosphorylation sur sa thréonine 592 et est recruté aux sites de cassures. D'autres travaux ont confirmé l'importance de la régulation de SAMHD1 au cours du cycle cellulaire, sa surexpression et sa réduction induisant toutes deux un ralentissement de la prolifération cellulaire. En complément de mes résultats, quelques études suggèrent que SAMHD1 joue un rôle dans le maintien de l'intégrité du génome, qui pourrait être dû à son effet sur la réponse aux dommages à l'ADN. Dans l'ensemble, ces résultats font de SAMHD1 un garant de l'homéostasie cellulaire. J'ai de plus montré que l'expression de SAMHD1 est réduite chez environ 80% des patients souffrant de leucémie lymphoïde chronique. La perte de cette protéine est donc corrélée à l'apparition d'une maladie découlant de la perturbation du fonctionnement cellulaire. L'étude d'échantillons d'autres types de tumeurs montre que, dans de moindres proportions, l'altération de l'expression de SAMHD1 est une caractéristique générale des cancers. Mes travaux de doctorat soulignent ainsi le rôle fondamental de SAMHD1 dans le maintien de l'intégrité cellulaire<br>Understanding host pathogen interactions reveals not only important information regarding the replication cycle of the pathogen but it often leads to the discovery and better understanding of key biological processes of the host. The aim of my PhD was to decipher the cellular functions of the HIV-1 restriction factor SAMHD1. SAMHD1 (SAM domain and HD domain-containing protein 1) is expressed in most human tissues. This protein is able to hydrolyze cellular deoxyribonucleotides triphosphate (dNTP) and possesses a nuclease activity primarily against single stranded RNA. Mutations in SAMHD1 have been described in patients suffering from an auto-immune disease causing premature death of newborns. This phenotype suggests a role of SAMHD1 in the control of immune response. Moreover, SAMHD1 restricts HIV-1 in non-cycling cells. The HIV-2 accessory protein Vpx induces SAMHD1 degradation by the proteasome, conferring cell permissiveness to HIV. In fact, the antiviral activity of SAMHD1 has been extended to other viruses including Herpes Simplex Virus 1 and Hepatitis B virus. Nevertheless, the mechanism by which SAMHD1 restrict HIV replication is debated. It was initially thought to act by depleting the dNTP pool but recent studies highlighted a potential role of SAMHD1 nuclease function in degrading HIV-1 genomic RNA. Many studies aiming at understanding the antiviral activity of SAMHD1 are being pursued, whereas little is known about the cellular function of this protein. The fact that SAMHD1 is able to regulate the cellular dNTP pool and to interact with nucleic acids suggests a key role of this protein in cellular processes, such as DNA replication and repair. During my PhD, I showed that SAMHD1 modulates the cell cycle, as the overexpression of this protein slows down cell proliferation. I also observed that SAMHD1 overexpression increases cellular sensitivity to double strand DNA breaks-inducing agents. Moreover I discovered that, after double strand breaks induction, SAMHD1 is specifically regulated by phosphorylation on its threonine 592 and recruited at the damaged sites. Other studies confirmed the importance of SAMHD1 regulation along the cell cycle as its overexpression and depletion both decrease cell proliferation. In addition to my observations, some studies suggested that SAMHD1 is important to maintain genomic integrity, presumably through its implication in DNA repair. Altogether, these results promote SAMHD1 as a key player in cellular homeostasis. I additionally showed that SAMHD1 expression is reduced in 80% of patients suffering from chronic lymphocytic leukemia (CLL). SAMHD1 loss is therefore correlated to the development of a disease due to disturbances of cellular integrity. Looking at samples from different types of tumors, I showed that SAMHD1 loss is shared between all tested cancers, although at lesser extent than in CLL. My PhD work underlines the central role of SAMHD1 to maintain cellular integrity
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Silva, Maria-João. "Role of CTF18 and SAMHD1 in human DNA replication and genome integrity maintenance." Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20236.
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La phase S est une période critique du cycle cellulaire au cours de laquelle le génome est particulièrement vulnérable. La duplication efficace des génomes eucaryotes dépend de la progression de milliers de fourches de réplication. Les premières étapes de la tumorigenèse sont associées au stress de réplication spontané, caractérisé par un blocage de la fourche. Comprendre comment le stress de réplication survient dans les cellules normales et contribue à la tumorigenèse est un grand défi dans la recherche sur le cancer. Mon travail de thèse vise à comprendre la régulation de la progression de la fourche de réplication par deux protéines différentes,SAMHD1 et CTF18, qui participent à divers aspects du métabolisme de l'ADN.La duplication du génome dépend d'un approvisionnement équilibré de désoxyribonucléosides triphosphates (dNTP).Des pools de dNTP déséquilibrées augmentent les taux de mutation. SAMHD1 a été identifié comme une triphosphohydrolase de dNTPs. Cette enzyme est impliquée dans le syndrome d'Aicardi-Goutières. Récemment, il a été montré que SAMHD1 est impliquée dans la régulation des pools de dNTPs dans des cellules humaines. Cette protéine est exprimée au maximum pendant la quiescence et peu en phase S. Cependant, l'impact de SAMHD1 sur la réplication de l'ADN n'a pas encore été abordée. En utilisant la technique DNA fiber spreading, nous avons constaté que SAMHD1 module la vitesse de progression de la fourche. En plus de son activité de dNTPase, SAMHD1 contient un domaine putatif 3'-5 'exonucléase qui clive à la fois l'ADN et l'ARN in vitro. Un nombre croissant de preuves indique que les exonucléases 3'-5 'sont essentielles pour assurer la progression de la fourche et la fidélité de la réplication de l'ADN. Nous avons constaté que l'activité d'exonucléase de SAMHD1 favorise le backtracking des fourches arrêtées et qu'elle est requise pour la progression normale des fourches de réplication. Nous proposons que cette activité de backtracking est importante pour enlever désoxynucléotides ou ribonucléotides mal incorporés. Au-delà du cancer, notre découverte pourrait avoir des implications pour la compréhension du lien entre SAMHD1 et le syndrome d'Aicardi-Goutières. CTF18 fait partie d'un complexe de type RFC impliqué dans la cohésion des chromatides sœurs (CCS). Dans les cellules humaines, il a été suggéré que CTF18 contrôle la progression des fourches de réplication, en favorisant l'acétylation de la cohésine SMC3 à la fourche de réplication. Cependant, plusieurs résultats indiquent que la fonction de CTF18 n'est pas limitée à la mise en place de la CCS.En effet, notre groupe a montré que Ctf18 chez la levure est essentielle pour l'activation du checkpoint de la réplication, indépendamment de son rôle dans la CCS.Chez l'homme, CTF18 participe également au recrutement de PCNA, le facteur de processivité des ADN polymérases δ et ε. CTF18 interagit également avec la polymérase translésionnelle ƞ. Le but de mon travail était de caractériser le rôle de CTF18 lors de la réplication de l'ADN. En utilisant le peignage moléculaire, nous avons remarqué que la vitesse de la fourche de réplication est plus lente dans les cellules dépletés en CTF18 dans une phase S normale.Curieusement, l'augmentation de la vitesse de la fourche a été observée dans les cellules dépletés en CTF18 traités avec l'hydroxyurée (HU), qui ressemble au phénotype des cellules dépletés pour SAMHD1. Avec l'utilisation de la technique iPOND, nous avons observé une accumulation de PCNA aux fourches de réplication dans les cellules CTF18 traités avec HU. Nous avons également constaté que la déplétion de CTF18 induit une accumulation de yH2AX, ce qui suggère que CTF18 est nécessaire pour la stabilité du génome. Enfin, nous avons observé que la résection dépendante de SAMHD1 ne se produit pas en l'absence de CTF18. Collectivement, ces données indiquent que CTF18 agit en amont de SAMHD1 aux fourches arrêtées, probablement par le déchargement de PCNA<br>S phase is a critical period of the cell cycle during which the genome is particularly vulnerable. The efficient duplication of eukaryotic genomes depends on the unperturbed progression of thousands of replication forks.The early stages of tumorigenesis are associated with spontaneous replication stress, characterized with a blockage of fork progression. Understanding how replication stress arises in normal cells and contributes to tumorigenesis is a major challenge in cancer research.My thesis work aims at understanding the regulation of replication fork progression by two different proteins, SAMHD1 and CTF18, which have important roles in various aspects of DNA metabolism.Faithful duplication of the genome depends on a balanced supply of deoxyribonucleoside triphosphates (dNTPs). Imbalanced dNTP pools decrease the fidelity of DNA polymerases and increase mutation rates. SAMHD1 was originally identified as a dNTP triphosphohydrolase. This enzyme is implicated in Aicardi-Goutières syndrome. It has also been identified as a component of the human innate immune system that restricts HIV-1 infection. Recently, SAMHD1 was shown to be involved in the regulation of dNTP pools in cultured human cells. This protein is maximally expressed during quiescence and minimally during S phase. However, the impact of SAMHD1 upon DNA replication has not been addressed. Using DNA fiber spreading, we found that SAMHD1 modulates the speed of fork progression. In addition to its dNTPase activity, SAMHD1 contains a putative 3'-5' exonuclease domain that cleaves both DNA and RNA in vitro. A growing body of evidence indicates that 3'-5' exonucleases are critical to ensure fork progression and the fidelity of DNA replication. Remarkably, we found that the exonuclease activity of SAMHD1 promotes backtracking at paused forks and is important for replication fork progression. We propose that this backtracking activity is important to remove miss-incorporated deoxynucleotides or ribonucleotides. Our finding may have implications for our understanding of the link between SAMHD1 and the Aicardi-Goutières syndrome.CTF18 is part of a RFC-like complex involved in sister chromatid cohesion (SCC). In human cells it has been suggested that CTF18 controls the progression of replication forks, presumably by promoting acetylation of the SMC3 cohesin at replication forks. However, several results indicate that the function of CTF18 is not restricted to the establishment of SCC. Indeed, our group has shown that the yeast Ctf18 is essential for activation of the replication checkpoint, independently of its role in SCC. In human, CTF18 also participates in the recruitment of PCNA, the processivity factor of DNA polymerases δ and ε. CTF18 also interacts with the translesion polymerase . The aim of my work was to characterize the role of CTF18 during DNA replication. Using DNA combing, we first noticed that replication fork speed is slower in CTF18-depleted cells under unperturbed conditions. Intriguingly, increased fork speed was observed in CTF18-depleted cells challenged with hydroxyurea (HU), which is reminiscent of the phenotype of SAMHD1-depleted cells. Using iPOND, we observed an accumulation of PCNA at replication forks in HU-treated CTF18-depleted cells. We also found that CTF18 depletion induces an accumulation of yH2AX, suggesting that CTF18 is required for genome stability. Finally, we observed that the resection mediated by SAMHD1 at paused forks does not occur in the absence of CTF18. Together, these data indicate that CTF18 acts upstream of SAMHD1 at stalled forks, presumably through the unloading of PCNA
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Qin, Zhihua. "SAMHD1 Negatively Regulates the Innate Immune Responses to Inflammatory Stimuli and Viral Infection." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587587968104986.
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Cenker, Jennifer Jean. "DIFFERENTIAL HIV-1 SUSCEPTIBILITY OF PRIMARY MACROPHAGE POPULATIONS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1491656059069304.
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Wang, Feifei. "Comparison of Murine and Human SAMHD1’s Role in Retroviral Restriction and Cell Cycle Progression." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1448450028.
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Coquel, Flavie. "Etude du rôle de SAMHD1 dans la réponse au stress réplicatif et la production d’interférons de type I." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTT043/document.
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La réplication de l’ADN est un processus extrêmement complexe, impliquant des milliers de fourches de réplication progressant le long des chromosomes. Ces fourches sont fréquemment ralenties ou arrêtées par différents obstacles, tels que des structures secondaires de l’ADN, des protéines agissant sur la chromatine ou encore un manque de nucléotides. Ce ralentissement, qualifié de stress réplicatif, joue un rôle central dans le développement tumoral. Des processus complexes, qui ne sont pas encore totalement connus, sont mis en place pour répondre à ce stress. Certaines nucléases, comme MRE11 et DNA2, dégradent l’ADN néorépliqué au niveau des fourches bloquées, ce qui permet le redémarrage des réplisomes.La voie interféron est un mécanisme de défense contre les agents pathogènes qui détecte la présence d’acides nucléiques étrangers dans le cytoplasme et active la réponse immunitaire innée. Des fragments d’ADN issus du métabolisme de l’ADN génomique (réparation, rétrotransposition) peuvent diffuser dans le cytoplasme et activer cette voie. Une manifestation pathologique de ce processus est le syndrome d’Aicardi-Goutières, une maladie rare caractérisée par une inflammation chronique générant des problèmes neurodégénératifs et développementaux. Dans le cadre de cette encéphalopathie, il a été suggéré que la réplication de l’ADN pouvait générer des fragments d’ADN cytosoliques, mais les mécanismes impliqués n'avaient pas été caractérisés.SAMHD1 est fréquemment muté dans le syndrome d’Aicardi-Goutières ainsi que dans certains cancers, mais son rôle dans l’étiologie de ces maladies était jusqu’à présent largement inconnu. Ce facteur de restriction du VIH possède une activité dNTPase impliquée dans la régulation des pools de nucléotides en G1, ainsi qu’une activité 3’-5’ exonucléase qui est, encore aujourd’hui, controversée.Le but de mon projet de thèse était de comprendre les mécanismes moléculaires responsables de l’inflammation dans les cellules déficientes pour SAMHD1.Nous montrons que de l’ADN cytosolique s’accumule dans les cellules déficientes pour SAMHD1, particulièrement en présence de stress réplicatif, activant la réponse interféron. Par ailleurs, SAMHD1 est important pour la réplication de l’ADN en conditions normales et pour le processing des fourches arrêtées, indépendamment de son activité dNTPase. De plus, SAMHD1 stimule l’activité exonucléase de MRE11 in vitro. Lorsque SAMHD1 est absent, la dégradation de l’ADN néosynthétisé est inhibée, ce qui empêche l’activation du checkpoint de réplication et entraine un défaut de redémarrage des fourches de réplication. De plus, la résection des fourches de réplication est réalisée par un mécanisme alternatif qui libère des fragments d’ADN dans le cytosol, activant la réponse interféron.Les résultats obtenus pendant ma thèse montrent, pour la première fois, un lien direct entre la réponse au stress réplicatif et la production d’interférons. Ces résultats ont des conséquences importantes dans notre compréhension du syndrome d’Aicardi Goutières et des cancers liés à SAMHD1. Par exemple, nous avons démontré que MRE11 et RECQ1 sont responsables de la production des fragments d’ADN qui déclenchent la réponse inflammatoire dans les cellules déficientes pour SAMHD1. Nous pouvons donc imaginer que bloquer l’activité de ces enzymes pourrait diminuer la production des fragments d’ADN et, in fine, l’activation de l’immunité innée dans ces cellules. Par ailleurs, la voie interférons joue un rôle essentiel dans l’efficacité thérapeutique de l’irradiation et de certains agents chimiothérapiques comme l’oxaliplatine. Moduler cette réponse pourrait donc avoir un intérêt beaucoup plus large en thérapie anti-tumorale<br>DNA replication is an utterly complex process, implicating thousands of replication forks that progress along chromosomes. These forks frequently slow-down or stall when they encounter obstacles such as DNA secondary structures, proteins acting on chromatin or a lack of dNTPs. Such impediment on the progression of replication forks, termed replication stress, plays a major role in tumorigenesis. Intricate processes, still not entirely understood, are established to respond to this stress. For instance, nucleases such as DNA2 and MRE11 degrade nascent DNA at arrested forks to allow their restart.The interferon pathway is a defense mechanism against pathogens that detects non-self-nucleic acids in the cytosol to activate the innate immune response. However, DNA fragments originating from the metabolism of genomic DNA, such as DNA repair and retrotransposition, may also diffuse into the cytosol to activate this pathway. The Aicardi-Goutières Syndrome (AGS), a rare genetic disorder characterized by neurological and developmental defects is caused by chronic inflammation due to the over-production of type I IFNs. It has been proposed that DNA replication may generate cytosolic DNA fragments triggering this encephalopathy. However, the mechanisms involved have remained unexplored.SAMHD1 is frequently mutated in the Aicardi-Goutières Syndrome as well as in some cancers. However, its role in the etiology of these diseases remains poorly understood. This HIV-1 restriction factor has a dNTPase activity involved in the regulation of dNTP pools and a putative 3’-5’ exonuclease activity.The goal of my PhD thesis was to understand the molecular mechanisms responsible for inflammation induced by SAMHD1 deficiency.We show that cytosolic DNA accumulates in SAMHD1-deficient cells, especially in conditions of replication stress, activating the interferon response. In addition, we demonstrate that SAMHD1 is necessary for DNA replication and for the processing of arrested forks, independently of its dNTPase activity. SAMHD1 stimulates the exonuclease activity of MRE11 in vitro. In the absence of SAMHD1, nascent DNA degradation is inhibited, preventing replication checkpoint activation and fork restart. Besides, forks are aberrantly processed by an alternative pathway that generates cytosolic DNA fragments, thereby activating the interferon response.Altogether, we demonstrate for the first time a direct link between the DNA replication stress response and interferon production. This result has important consequences regarding our understanding of the Aicardi-Goutières Syndrome and cancers caused by SAMHD1 mutations, which could be translated into new therapeutic opportunities. For instance, we have shown that MRE11 and RECQ1 are responsible for the production of DNA fragments triggering the pro-inflammatory response in SAMHD1-deficient cells. Inhibiting these enzymes decreases the production of cytosolic nucleic acids and, consequently, reduces the activation of cell-autonomous innate immunity in SAMHD1-depleted cells. Accordingly, inhibiting these enzymes may as well decrease IFN production in AGS in vivo models caused by SAMHD1 mutations. The interferon pathway also plays a major role in tumorigenesis as well as in the clinical efficacy of irradiation and some chemotherapeutic agents such as oxaliplatin. Modulating this response may therefore have much broader implications in anti-cancer therapy
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Samih, Younes [Verfasser]. "Dialectal Arabic processing Using Deep Learning / Younes Samih." Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2018. http://d-nb.info/115091856X/34.
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Deutschmann, Janina [Verfasser], Thomas [Akademischer Betreuer] Gramberg, and Robert [Gutachter] Slany. "Regulatory Mechanism of the Innate Restriction Factor SAMHD1 in Herpesviral Infections / Janina Deutschmann ; Gutachter: Robert Slany ; Betreuer: Thomas Gramberg." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2020. http://d-nb.info/1221370456/34.
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Thientosapol, Sanchai. "Mechanisms of transversion mutation are dependent on sequence context and nucleotide paucity during antibody somatic hypermutation." Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/20061.
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Somatic hypermutation of antibodies during humoral immune responses depends on expression of Activation Induced Deaminase (AID) in antibody-producing B cells. AID initiates somatic hypermutation by converting cytosine (C) residues in antibody genes into uracil (U) residues, by deamination. Alone, conversion of cytosine into uracil can only produce C:G to T:A transition mutations, by replication across U (phase 1A mutation). Processing of C deaminations by base excision repair (BER) or mismatch repair (MMR) diversifies mutation, predominantly at C:G (phase 1B mutation) and A:T (phase 2 mutation), respectively. Mutations at C along the Ig variable region are not equally distributed. AID de-aminates C more often if they occur as part of WRCY motif (A/T,A/G,C,C/T). WRCY sequences are concentrated in hypervariable regions of Ig genes, where nucleotide substitutions are likely to be effective at generating useful amino acid substitutions to optimize affinity maturation. Of all WRCY motifs, AGCT and AACT are the most mutated hotspots. AGCT is also enriched in switch regions and facilitates CSR. In Chapter three, using large datasets of a transgenic mouse model, I compared Igh hypermutation between SWHEL B cells, SWHEL B cells deficient for UNG2 via retroviral expression of the uracil glycosylase inhibitor (ugi), SWHEL B cells deficient for MutSα by crossing Msh2ko alleles into SWHEL mice and SWHEL B cells deficient for both UNG2 and MutSα. I found that phase 1B mutations occur by distinct MMR-independent or MMR dependent pathways. At or in proximity to AGCW motifs, phase 1B mutations were driven by UNG2 without requirement for mismatch repair. Deaminations in AGCW were refractive both to processing by UNG2 and to high-fidelity base excision repair (BER) downstream of UNG2, regardless of mismatch repair activity. Outside AGCW motifs, transversions at C:G are co-dependent on UNG2 and MMR. Classically, MMR mediates high fidelity repair of mismatches introduced during replication. The reasons for the profound differences in repair accuracy between classical and AID-induced MMR have not been elicited. During S-phase of the cell replication cycle, when classical post-replication MMR occurs, nucleotide triphosphate (dNTP) levels are optimal for DNA replication, while in G1-phase dNTP levels are lower. Since there is evidence that AID is active in G1-phase, we hypothesized that low dNTP levels may be the cause of low fidelity MMR. Two enzymes are the major determinant of dNTP pools: ribonucleotide reductase (RNR), which converts ribonucleotides into deoxyribonucleotides predominantly during S-phase, and SAMHD1, which degrades dNTPs predominantly outside of S-phase. In Chapters four and five, I quantified antibody hypermutation in B cells lacking SAMHD1 and/or over-expressing RNR. I observed a 2-fold decrease in mutations at A:T bases in cells lacking SAMHD1. This decrease was comparable to the decrease induced by RNR over-expression and was consistent with our hypothesis. Unexpectedly, loss of SAMHD1 also decreased transversion mutations at C:G by about 70%, and almost doubled transition mutations at C:G bases. RNR over-expression had no obvious impact on transversion mutations at C:G, but increased transition mutations at C:G bases similarly to loss of SAMHD1. Furthermore, loss of SAMHD1 decreased AID/BER-dependent antibody class switch recombination, while RNR over-expression did not. These findings indicate that dNTPs play a role in MMR-mediated antibody mutation, as predicted by our hypothesis, but they also indicate a major role for SAMHD1 in AID-induced BER that was not predicted by our hypothesis or by current models of antibody hypermutation. This important finding warrants further investigation to identify the mechanism.
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Abe, Junya. "A nationwide survey of Aicardi-Goutieres syndrome patients identifies a strong association between dominant TREX1 mutations and chilblain lesions: Japanese cohort study." Kyoto University, 2014. http://hdl.handle.net/2433/188647.
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Hallaq, Sameh [Verfasser]. "Human Capital in Palestine: Causes and Consequences / Sameh Hallaq." Wuppertal : Universitätsbibliothek Wuppertal, 2019. http://d-nb.info/1196132283/34.
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Jaffer, Ali Mohammed Hakim. "Multifaceted roles of the transmembrane nuclear envelope protein, Samp1." Doctoral thesis, Stockholms universitet, Institutionen för neurokemi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-141816.
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The eukaryotic nuclear envelope (NE), separates the nucleoplasm from cytoplasm and is made up of two concentric lipid membranes, the outer and the inner nuclear membranes (ONM and INM), the nuclear pore complexes (NPCs) and an underlying filamentous nuclear lamina. The INM contains hundreds of unique transmembrane proteins of which only a handful have been characterized. In this thesis, I aimed to understand the functional organization of proteins in the nuclear envelope and I focused on investigating the functions of a recently identified INM transmembrane protein, Samp1. We have developed a novel and robust approach, MCLIP, to identify specific protein-protein interactions taking place in live cells. Using MCLIP, we have shown that Samp1 interacts with proteins of the LINC complex, the nuclear lamina and components of the mitotic spindle. Samp1's specific interactions with a variety of binding partners, suggest that Samp1 plays important roles both in interphase and in mitosis. We have also shown that Samp1 can provide a binding site at the INM for the GTPase Ran, a master regulator of protein interactions in interphase and in mitosis. Furthermore, we have also investigated the role of Samp1 in cell differentiation using two independent model systems. In human iPSCs, ectopic expression of Samp1 promoted differentiation despite pluripotent culture conditions. In C2C12 myoblast, depletion of Samp1 completely blocked differentiation into myotubes. The two studies complement each other and suggest that Samp1 has a strong differentiation promoting activity. Taken together, the findings in this thesis, give insights on the unexpected and unforeseen roles played by a transmembrane protein in different fundamental cellular process.<br><p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript. Paper 5: Manuscript.</p>
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Herrmann, Alexandra [Verfasser], Thomas [Akademischer Betreuer] Gramberg, and Lars [Gutachter] Nitschke. "The role of SAMHD1 in restriction and immune sensing of retroviruses and retroelements / Alexandra Herrmann ; Gutachter: Lars Nitschke ; Betreuer: Thomas Gramberg." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2018. http://d-nb.info/1164768514/34.
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Martinat, Charlotte. "Rôle de la sumoylation dans les activités de SAMHD1, un facteur de restriction du VIH-1 dans les cellules non cyclantes." Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCC246.
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Depuis sa découverte il y a sept ans, les recherches intensives sur SAMHD1 en ont fait un facteur cellulaire important qui limite la réplication du virus de l’immunodéficience humaine de type 1 (VIH-1) à l’étape de transcription inverse dans les cellules immunitaires non-cyclantes. Le VIH-2 et certains virus de l’immunodéficience simienne (VIS) surmontent cette restriction en exprimant la protéine Vpx, qui conduit SAMHD1 à sa dégradation protéasomique. De nombreuses données expérimentales indiquent que l’activité triphosphohydrolase (dNTPase) de SAMHD1, qui diminue les niveaux cellulaires de dNTP, est responsable de la restriction. Cependant, la seule expression de SAMHD1 ne suffit pas à rendre les cellules résistantes à l’infection par le VIH-1 et ce quel que soit le type cellulaire. De plus, il n’existe pas de corrélation stricte entre la fonction neutralisante de SAMHD1 et sa capacité à dégrader les dNTP. Il a été suggéré que la phosphorylation du résidu T592 puisse inhiber les fonctions antivirales de SAMHD1 dans les cellules en division. Cependant, l’étude de mutants phospho-mimétiques ou phospho-ablatifs mène à des résultats contradictoires. Ces données permettent d’envisager que l’activité antivirale de SAMHD1 ne repose pas exclusivement sur son activité dNTPase et que sa régulation ne peut pas être expliquée que par la phosphorylation. Nous avons démontré que SAMHD1 est modifiée par la SUMOylation, i.e. une modification post-traductionnelle consistant en la conjugaison réversible des protéines SUMO ; et avons identifié les sites principaux modifiés. Nos résultats indiquent que les mutations empêchant la SUMOylation de SAMHD1, particulièrement celle du résidu K595 adjacent au résidu phosphorylable T592, invalident sa fonction antivirale sans affecter son activité dNTPase. Un phénotype similaire est observé après suppression de la région C-terminale de SAMHD1 (résidus 595-626). Nous suggérons donc que les résidus K595 SUMOylé et T592 phosphorylé font partie d’une interface responsable du recrutement d’un co-facteur méconnu, dépendant du type cellulaire, et pouvant jouer un rôle dans le mécanisme de restriction de l’infection par le VIH-1. Notre travail permet d’entrevoir un nouvel aspect de la régulation de SAMHD1 et contribue à la caractérisation des mécanismes moléculaires sous-jacents à son pouvoir antiviral. L’identification d’un ou plusieurs partenaires cellulaires de SAMHD1 permettra de mieux comprendre le mécanisme de restriction et pourra servir de cible thérapeutique pour combattre l’infection par le VIH-1<br>Since its discovery seven years ago, SAMHD1 has emerged as an important cellular factor that limits the replication of the Human immunodeficiency virus type 1 (HIV-1) at the reverse transcription step in non-cycling immune cells. HIV-2 and some SIV overcome this restriction by encoding the Vpx protein, which bridges SAMHD1 to the proteasomal degradation pathway. A wealth of experimental evidence indicates that SAMHD1 triphosphohydrolase (dNTPAse) activity, which is responsible for cellular dNTP pools depletion, accounts for the premature termination of viral replication. Notably, SAMHD1 expression is not sufficient to render any tested cell type resistant to HIV-1. Besides, there is no strict link between SAMHD1 capacity to deplete dNTP pools and its neutralizing function. Phosphorylation of residue T592 is proposed to downregulate the antiviral function of SAMHD1 in cycling cells. However, the analysis of phosphomimetic or unphosphorytable mutants of SAMHD1 leads to contradictory results. Altogether, these data suggest that SAMHD1-mediated restriction may neither exclusively rely on its dNTPase activity, nor solely depend on the phosphorylation status of T592.We have demonstrated that SAMHD1 undergoes SUMOylation, i.e. a post-translational modification consisting in the reversible conjugation of SUMO on a target protein; and have identified the major sites of modification. Our results show that mutations preventing SAMHD1 SUMOylation, in particular at residue K595 that lies close to the phosphorytable T592 site, inhibit its antiviral properties without impairing its dNTPase activity. Notably, an analogous phenotype is observed upon deletion of SAMHD1 C-terminus (Δ595-626). Based on these data, we speculate that phosphorytable T592 and SUMOylated K595 residues are part of an interface in SAMHD1 C-terminal tail that is responsible for the recruitment of still unknown cofactor(s) involved in the mechanism of HIV-1 infection restriction. Our work highlights a novel aspect of SAMHD1 regulation and participates to the characterization of molecular basis underlying its antiviral function. The identification of one or several cellular partners will allow a better understanding of retroviral restriction mechanism and could serve as new therapeutic targets to fight HIV-1 infection
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COGHI, MARIA DONATA. "Samdi mass spectrometry for high yield protein modification reaction development." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2014. http://hdl.handle.net/10281/50887.
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Efficient chemical strategies that attach synthetic molecules to desired positions on protein surfaces are useful tools in the field of chemical biology and represent one major prerequisite for the development of new drugs and materials. Protein modification with polyethylene glycol (PEG) groups is indeed routinely performed on therapeutic proteins to improve serum half-life, or even cytotoxins or imaging agents are efficiently conjugated to cancer-targeting elements. In a typical approach, a synthetic functional group of interest is attached to a uniquely reactive amino acid group introduced by recombinant methods. Most bioconjugation reactions, however, do not reach full conversion. Therefore the development of a straightforward and reliable method to increase the extent of conversion into bioconjugates would be very helpful. In this perspective, we developed a generalizable combinatorial peptide library screening platform suitable for the identification of sequences displaying high levels of reactivity toward a desired bioconjugation reaction. This was achieved by using SAMDI MS technique (Self-Assembled Monolayer and Desorption/Ionization Mass Spectrometry) as a new, efficient and simple method for the evaluation of highly reactive amino acid motifs. The bioconjugation reaction we selected is the oxidative modification of electron-rich tyrosine residues performed using cerium(IV) ammonium nitrate (CAN) as oxidant reagent. The peptides were identified on a 361-member hexapeptide array, wherein the two N- and C-terminal residues to the target residue were varied. The arrays were prepared by immobilizing the peptides to a self-assembled monolayer of alkanethiolates on gold and could therefore be analyzed by mass spectrometry. We found that the most reactive peptides had either a serine N-terminal to the tyrosine residue or another tyrosine in proximity of the reactive site. Conversely, peptides displaying the lowest conversion level contained a positive charged residue: histidine, lysine or arginine, where the lowest relative activity was reached with arginine and leucine as C- and N- terminal residues, respectively. This study provides an important example of how synthetic peptide libraries can accelerate the discovery and optimization of protein bioconjugation strategies.
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Wichit, Sineewanlaya. "Rôle du cholestérol, de la protéine SAMHD1 et de la salive d’Aedes aegypti dans l’infection des cellules cutanées par le virus Chikungunya." Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTT037.
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Le virus Chikungunya (CHIKV), arbovirus en pleine ré-émergence, a envahi rapidement de nombreuses zones géographiques du monde. La propagation mondiale de ce virus constitue une menace pour la santé humaine car il n'y a pas de vaccin ou d'agents antiviraux appropriés pour contrôler l'infection virale. La transmission du virus s’effectue lors de la piqure d’un moustique infecté du genre Aedes, qui injecte sa salive contenant le virus dans la peau de l’hôte humain. Afin de contrôler la dissémination du virus, il est primordial de développer des recherches sur l’identification de molécules antivirales et de comprendre les mécanismes moléculaires impliqués dans les interactions hôte-virus et/ou vecteur-virus-hôte. En utilisant différentes stratégies moléculaires et cellulaires, nous avons étudié le potentiel antiviral de l'Imipramine, une molécule déjà commercialisée et qui a la capacité de perturber le transport du cholestérol intracellulaire. Nous avons démontré que cette molécule est capable d'inhiber la réplication du CHIKV dans les fibroblastes cutanés humains. Nous avons mis en évidence que l'Imipramine affectait à la fois les étapes de fusion et de réplication pendant le cycle de réplication du virus. En outre, la molécule a également fortement inhibé la réplication de plusieurs Flavivirus comme le virus Zika (ZIKV), le virus du Nil occidental et le virus de la Dengue. Nous avons également déterminé le profil protéomique global des fibroblastes humains infectés par le CHIKV ou le ZIKV. Cela nous a permis de mettre en évidence les modulations significatives de plusieurs protéines stimulées par l'interféron et de protéines impliquées dans à la défense anti-virale dans les cellules infectées. Plus important encore, nos résultats montrent pour la première fois le rôle de la protéine SAMHD1 dans l'infection des fibroblastes cutanés par les arbovirus. Enfin, compte tenu des fortes interactions entre l’hôte, le vecteur et le CHIKV, l'effet de la salive du moustique Ae. Aegypti sur l'infection virale a été étudié. À notre connaissance, cette étude est la première à montrer l’importance de la salive d’Ae. aegypti sur la facilitation de l’infection du CHIKV, dans des fibroblastes cutanés, à travers la régulation des gènes impliqués dans la réponse interféron de type I<br>Chikungunya virus (CHIKV) is a re-emerging mosquito-borne alphavirus that has been spread worldwide. The dissemination of this virus is a threat to human health since there is no approved vaccine or appropriate antiviral agents to control viral infection. The global expansion of the virus is preceded by biting of infected Aedes mosquitos, which injects saliva containing the virus into the skin of the human host. Searching for effective antiviral compounds and understanding of the molecular mechanisms involved in host-virus or vector-virus-host interactions are crucial for controlling viral spread.Using different molecular and cellular strategies, we demonstrated that the FDA approved drug, imipramine, which has the capability to disturb intracellular cholesterol transport inhibits CHIKV replication in human skin fibroblasts. Imipramine was found to affect both the fusion and replication steps of the viral life cycle. Moreover, it also strongly inhibited the replication of several Flaviviridae family members, including Zika, West Nile and Dengue virus. We have also determined the global proteomic profile of Chikungunya and Zika virus infected human skin fibroblasts, and found that several interferon-stimulated proteins and antiviral response proteins are significantly up-regulated in the infected cells. More importantly, our results also provided for the first time a role of SAMHD1 in arbovirus infection of human skin fibroblasts. Finally, we demonstrated that Aedes aegypti saliva enhances CHIKV replication in human skin fibroblasts. To our knowledge, this is the first report showing the importance of Aedes aegypti saliva on promoting CHIKV infection via down regulation of the genes involving type I IFN secretion in the infected human cutaneous cells
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Wallentin, Jan. "Vägar till samadhi : En granskning av Robert K. C. Formans begrepp Pure Consciousness Event." Thesis, Umeå universitet, Institutionen för idé- och samhällsstudier, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-184305.
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Jan Wallentin. Vägar till samadhi : en granskning av Robert K. C. Formans begrepp ”Pure Consciousness Event” (Roads to Samadhi : An Examination of Robert K. C. Forman’s Concept of ”Pure Consciousness Event”). Umeå University: Department of Historical, Philosophical and Religious studies. Bachelor thesis. June 2021.Is Robert K. C. Forman’s concept of ”pure consciousness event” an example of a universal,mystical core experience? Is it possible to establish the neural correlates of this proposedexperience, and to induce it experimentally? These are the main questions of this study,which is a literature review drawing on recent scientific research from three fields: religious studies, philosophy of consciousness and neuroscience.The major findings are:The concept of ”pure consciousness event” (PCE) does seem like a tenable way ofgetting around the constructivist critique regarding universal, mystical core experiences.However, Forman’s original definition of PCE seems too strict. Forman defines PCE as ”a wakeful though contentless (non-intentional) consciousness”, but in the conventional wisdom of contemporary philosophy it is deemed impossible to be conscious without beingconscious about something. A conceivable solution would be to replace the term ”PCE” withThomas Metzinger’s less strict term ”Minimal Phenomenal Experience” (MPE), whichallows for some, though minimal, mental content during these kind of experiences.Regarding neural correlates, several recent studies suggest that a high level of activityin the brain’s default mode network (DMN) is correlated with a heightened sense of self-awareness. A low level of activity in the DMN is, vice versa, correlated with a sense of self-forgetting, as in the flow-experience. However, the activity-level of the DMN does not seem to fully explain the proposed existence of pure consciousness events, even in a less strict definition of this term.Methods used to induce experiences reminiscent of PCE include the white dreams ofTibetan dream yoga (yoga nidrā), states of deep meditation, and the intake of psychoactive substances, like psilocybin, DMT and LSD.Keyterms: Robert K. C. Forman, pure consciousness event, mysticism, samadhi, philosophy of consciousness,Thomas Metzinger, minimal phenomenal experience, drug induced ego dissolution.
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Güthlein, Nora [Verfasser], and Alexander [Akademischer Betreuer] Rapp. "Geburtensaisonalität psychischer Störungen - Zum Effekt von meteorologischen Variablen / Nora Samiha Güthlein ; Betreuer: Alexander Rapp." Tübingen : Universitätsbibliothek Tübingen, 2017. http://d-nb.info/1199545929/34.
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Anabousi, Samah [Verfasser]. "Liposomal Drug Carrier Systems for Inhalation Treatment of Lung Cancer / Samah Anabousi." Aachen : Shaker, 2006. http://d-nb.info/1186583851/34.
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Argüelles, Camilla. "Étude du rôle de la protéine de liaison aux ARN messagers Smaug dans la voie Hedgehog chez la drosophile." Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCC053.
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Les protéines signal Hedgehog (HH) sont des acteurs majeurs du développement animal et de la carcinogenèse. Leur transduction requiert la protéine à 7 domaines transmembranaires Smoothened (SMO) dont l’activité est régulée par Patched (PTC), un récepteur et antagoniste d’HH. PTC et HH régulent le trafic, la phosphorylation et l’accumulation de SMO mais de nombreux aspects de sa régulation restent incompris. Au cours de ma thèse, j’ai travaillé sur Smaug, un nouveau partenaire de SMO chez la drosophile identifié au laboratoire dans un crible double-hybride. Smaug est connue pour lier et réprimer de nombreux ARNm au cours de l’embryogenèse chez la mouche. Durant ma thèse j’ai étudié comment Smaug agit sur SMO et la voie HH et aussi comment elle est régulée par HH. J’ai montré que Smaug était un régulateur positif de la voie HH et ce très probablement via sa capacité à fixer des ARNm. J’ai également montré que SMO et Smaug colocalisaient dans des foci cytoplasmiques en absence de signal et que Smaug était relocalisée à la membrane plasmique avec SMO en réponse à HH. Enfin j’ai mis en évidence un effet de SMO et d’HH sur la phosphorylation de Smaug suggérant une potentielle régulation en retour sur l’activité de Smaug. Ce travail m’a permis de proposer à la fois un nouveau rôle de la protéine de liaison aux ARN Smaug dans un processus de signalisation cellulaire ainsi que l’implication jusqu’ici insoupçonnée, d’une possible régulation post-transcriptionnelle d’ARNm dans la voie HH<br>Hedgehog Proteins (HH) are major players of animal development and carcinogenesis. Their transduction requires the 7 transmembrane protein Smoothened (SMO) whose activity is regulated by Patched (PTC), the HH receptor and antagonist. PTC and HH regulates SMO trafficking, phosphorylation and accumulation but numerous aspects of these regulations remain poorly understood. During my thesis, I focused on Smaug, a new partner of SMO in drosophila which was identified in the laboratory in a yeast two-hybrid screen. Smaug is known to bind and repress numerous mRNA during embryonic development in fly. I analyzed how it acts on SMO and HH signaling and also how is it regulated by HH. I have shown that Smaug is a positive regulator of the HH pathway and that it probably acts via its capacity to bind mRNA. I have also demonstrated that SMO and Smaug colocalise in cytoplasmic foci in absence of signal and that SMO is sufficient to localized Smaug to the plasma membrane in response to HH. Finally, I highlighted an effect of SMO and HH on the phosphorylation of Smaug suggesting the existence of a regulatory loop
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Miazzi, Cristina. "The role of deoxynucleotide trafficking and degradation in the maintenance of balanced pools of DNA precursors in mammalian cells." Doctoral thesis, Università degli studi di Padova, 2014. http://hdl.handle.net/11577/3423656.
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Deoxynucleoside triphosphates (dNTPs) are the precursors for DNA synthesis. Their balanced concentrations ensure the accuracy of nuclear and mitochondrial DNA replication and of DNA repair. dNTP pool sizes and relative proportions are regulated by a network of anabolic and catabolic enzymes, operating in the cytosol and in mitochondria. Cytosolic and mitochondrial pools are separated by the impermeable inner mitochondrial membrane but multiple evidences suggest the existence of mitochondrial carriers mediating the transport of deoxynucleotides between the two compartments. PNC1 has been identified as a pyrimidine nucleotide carrier by reconstitution in liposomes and its involvement in the import of UTP into mitochondria has been confirmed in human cells.
The main enzyme synthesizing dNTPs is the cytosolic ribonucleotide reductase (RNR). It provides the four DNA precursors in balanced amounts through a tight regulatory mechanism based on two distinct allosteric sites controlling catalytic activity and substrate specificity. Alternatively, dNTPs derive from the salvage of deoxynucleosides by subsequent phosphorylation steps in the cytosol and in mitochondria. Catabolic enzymes mediate the dephosphorylation of deoxynucleoside monophosphates and the degradation of deoxynucleosides. SAMHD1 is a recently identified catabolic enzyme with a dNTP triphosphohydrolase activity and is allosterically activated by dGTP to degrade the four dNTPs. It was first described as a restriction factor for HIV-1 infection in immune cells but its wide expression in most human tissues suggests that it may have a more general function.
The present work investigates the role of deoxynucleotide trafficking and degradation on the maintenance of dNTP pool balance focusing on three major issues: (i) the role of PNC1 in the trafficking of thymidine nucleotides in intact cells, (ii) the mechanism of allosteric regulation of SAMHD1 and (iii) its biological function in human cells.
We demonstrate that PNC1 is involved in the import of thymidine phosphates into mitochondria and in their export to the cytosol. Thymidine nucleotides are mostly synthesized de novo and by TK1-dependent salvage in the cytosol when cells are replicating their nuclear DNA, while the mitochondrial salvage of thymidine prevails outside S-phase. Thus, the bidirectional transport of thymidine nucleotides across the inner mitochondrial membrane maintains the intracellular equilibrium of the dTTP pool.
In human cells we find that SAMHD1 expression is cell-cycle regulated, highest in quiescence and minimal in S-phase. Manipulation of its expression through siRNAs disrupts the cell-cycle regulation of dNTP pools, which are present at low levels outside S-phase and expand in S to support the replication of the nuclear genome. Disregulation of dNTP pools disturbs the normal progression of the cell cycle by interfering with the G1/S transition. We describe a key role for SAMHD1 and its catabolic activity in maintaining DNA precursors at low concentrations in the G1-phase to allow a correct transition into S. Through a biochemical characterization of the recombinant mouse and human proteins we demonstrate the existence of two distinct regulatory sites for the control of SAMHD1 activity. We suggest that a common regulatory mechanism based on allostery operates on the two opposed reactions catalyzed by RNR and SAMHD1 to set dNTP pool balance.<br>I deossinucleosidi trifosfato (dNTPs) sono i precursori della sintesi del DNA. Le loro concentrazioni devono essere bilanciate affinchè la replicazione del DNA nucleare e mitocondriale e la riparazione del DNA siano accurate. Le dimensioni dei pool e le loro proporzioni sono regolate da una rete di enzimi anabolici e catabolici che operano nel citosol e nei mitocondri. I pool citosolico e mitocondriale sono separati dalla membrana mitocondriale interna che costituisce una barriera impermeabile, ma molte sono le evidenze dell'esistenza di trasportatori mitocondriali per lo scambio di deossinucleotidi tra i due compartimenti. PNC1 è stato identificato come un trasportatore di nucleotidi pirimidinici dopo essere stato ricostituito in liposomi; il suo ruolo nell'importo di UTP nei mitocondri è stato confermato in cellule umane. L'enzima principale per la sintesi dei dNTPs è la ribonucleotide reduttasi (RNR) nel citosol. L'enzima produce i quattro precursori del DNA in quantità bilanciate attraverso un meccanismo di regolazione allosterico basato su due siti distinti che controllano l'attività catalitica e la specificità di substrato. I dNTPs possono essere sintetizzati anche attraverso la via di recupero che consiste nella fosforilazione di deossinucleosidi nel citosol e nei mitocondri. Gli enzimi catabolici degradano i deossinucleosidi monofosfato e i deossinucleosidi. SAMHD1 è un enzima catabolico scoperto recentemente; è una dNTP trifosfoidrolasi ed è in grado di degradare i quattro dNTPs se attivato in maniera allosterica dal dGTP. E' stato recentemente identificato come il fattore di restrizione di HIV-1 nelle cellule del sistema immunitario, ma il fatto che sia ampiamente espresso in molti tessuti umani suggerisce che svolga una funzione più generale.
In questo lavoro abbiamo affrontato tre questioni principali: (i) il ruolo di PNC1 nel trasporto di nucleotidi della timidina, (ii) il meccanismo di regolazione allosterica di SAMHD1 e (iii) il suo ruolo nelle cellule umane.
Dimostriamo che PNC1 media l'importo dei fosfati della timidina nei mitocondri e contemporaneamente il loro esporto verso il citosol, allo scopo di mantenere l'equilibrio dei pool citosolico e mitocondriale del dTTP.
In cellule umane dimostriamo che l'espressione di SAMHD1 è regolata nel corso del ciclo cellulare, con un livello massimo al di fuori della fase S e un livello minimo nella fase di sintesi del DNA. Il suo ruolo è quello di mantere i pool dei dNTPs a basse concentrazioni in fase G1 per consentire l'entrata in S e la corretta progressione del ciclo cellulare. Attraverso la caratterizzazione biochimica della proteina, dimostriamo che la sua attività enzimatica è regolata in maniera complessa da due siti allosterici distinti.
Proponiamo che un meccanismo di regolazione comune basato su proprietà allosteriche operi sulle due reazioni opposte catalizzate da RNR e SAMHD1 per determinare un pool bilanciato di precursori.
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Leães, Roberta Nascimento. "Desenvolvimento de um sistema para avaliação de marcha em simulação de hipogravidade (SAMSH)." Pontifícia Universidade Católica do Rio Grande do Sul, 2006. http://hdl.handle.net/10923/3213.
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Previous issue date: 2006<br>This study aimed to develop a Walking Pattern Evaluation System during Hypogravity Simulation (SAMSH), which included the adaptation of a body suspension device, the instrumentation of a treadmill and the development of a virtual environment. The system was tested using only one subject because this research did not have the objective of validating SAMSH. Cinematic analyses were performed whilst one individual was walking on the treadmill during body weight reduction simulating the gravitational forces of the Moon (reduction of 60%) and Mars (reduction of 30%) with and without virtual reality glasses (Head Mounted Display, HMD). The walking pattern was evaluated by means of knee and ankle electrogoniometers, foot switches placed on the front and back part of the sole region, and five video cameras. Results showed that the body weight reduction during Moon simulation alter the walking pattern, including the increase in Step Time, Contact Time, Step Length and Air Time, and the decrease of Walking Cadence Time (steps per minute). The findings of this study also suggested that hypogravity simulation reduces walking effort. The utilization of the HMD allowed the evaluation of the head position threedimensionally during hypogravity simulation-. The virtual environment reduced postural balance, due to the absence of visual input to the subject, which was evidenced by a protective extension reaction.<br>Este estudo é referente ao desenvolvimento de um Sistema de Avaliação de Marcha em Simulação de Hipogravidade (SAMSH). Para tal, fez-se necessário o aprimoramento de um Sistema de Suspensão Corporal (SSC) e instrumentação de uma esteira elétrica para a construção de uma plataforma de movimento como uma técnica de locomoção física em um ambiente virtual. O SAMSH foi testado em um único indivíduo, pois este estudo não objetivou sua validação. Foram realizadas análises cinemáticas da marcha de um indivíduo caminhando sobre uma esteira elétrica em diferentes condições de redução de peso corporal (30% simulando gravidade Marciana e 60%, Lunar), com e sem a utilização de óculos de realidade virtual (Head Mounted Display, HMD). Os instrumentos utilizados para o processo de avaliação foram eletrogoniômeros de joelho e tornozelo, footswitches nas porções anterior e posterior da região plantar, e cinco câmeras de vídeo. Os resultados mostraram que uma redução de peso corporal de 60% (Grupo Lua) altera os parâmetros cinemáticos da marcha, aumentando o Tempo de Passada (TP), o Tempo de Contato (TC), o Comprimento de Passada e o Tempo Aéreo (TA) e diminuindo a Cadência da Marcha. Sugerem, igualmente, que em hipogravidade realiza-se menos esforço durante o ato de caminhar. A utilização do HMD durante a marcha sobre a esteira permitiu o rastreamento da posição da cabeça do indivíduo em um espaço tridimensional, apresentando diferenças de acordo com cada condição de redução de peso corporal. Além disso, o bloqueio do sistema visual pela transmissão de cenas virtuais causou déficit da manutenção do equilíbrio postural, o qual foi evidenciado, por exemplo, pela reação de extensão protetora.
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Kutzner, Juliane [Verfasser], and Martin [Akademischer Betreuer] Müller. "Dissecting SAMHD1´s role in the type I Interferon induced early block to HIV-1 infection and its connection to cancer / Juliane Kutzner ; Betreuer: Martin Müller." Heidelberg : Universitätsbibliothek Heidelberg, 2019. http://d-nb.info/1197904344/34.
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Marc, Corral Juan. "Molecular genetics of autosomal dominant ataxias: identification and characterisation of two novel spinocerebellar ataxia subtypes." Doctoral thesis, Universitat Autònoma de Barcelona, 2021. http://hdl.handle.net/10803/672062.
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Les atàxies espinocerebel·loses (SCAs) consisteixen en un grup heterogeni de trastorns del moviment hereditaris caracteritzats clínicament per atàxia progressiva associada de forma variable amb altres signes neurològics addicionals com són signes piramidals o extrapiramidals, oftalmoplegia, retinosi pigmentària, demència o convulsions. Aquesta heterogeneïtat clínica s’explica per l’heterogeneïtat genètica, amb més de 53 loci i 40 gens identificats i associats fins a dia d’avui. En aquesta tesi s’ha estudiat una cohort de 308 pacients amb atàxia, identificant variants genètiques causatives en 82 casos índex (26,6%), 45 d’elles no descrites prèviament. Durant el curs d’aquesta tesi, el nostre grup va identificar un nou subtipus d’atàxia, la SCA37, i va localitzar el seu defecte genètic en el cromosoma 1p32. En el present estudi s’ha identificat la mutació intrònica repetitiva i inestable ATTTC dins de la regió reguladora 5 ‘no codificant de el gen Disabled 1 (DAB1) com el defecte genètic causant de la SCA37. A més, es descriu la correlació clínica i genètica i les primeres troballes neuropatològiques en SCA37 que indiquen que la malaltia està causada per la desregulació de l’expressió del DAB1 en el cerebel amb pèrdua severa de cèl·lules de Purkinje en l’escorça cerebel·losa i la presència de grànuls perisomàtics ubiquitinats i immunotenyits per DAB1. És important destacar que la repetició ATTTC desregula l’expressió de l’ARN de DAB1 resultant en la sobreexpressió de la ruta de senyalització de la reelina-DAB1 i PI3K/AKT en el cerebel SCA37.
Finalment, però no menys important, s’han realitzat estudis de lligament de el genoma complet i seqüenciació de l’exoma en una família de Menorca amb set individus afectes que presentaven atàxia, nistagme, disàrtria, polineuropatia i signes piramidals de forma variable amb una herència autosòmica dominant. L’edat d’inici de la malaltia oscil·la entre els 15 i 50 anys. Les ressonàncies magnètiques van revelar atròfia cerebel·losa amb desmielinització cerebral, i els estudis neurofisiològics van mostrar polineuropatia sensitiva axonal moderada amb resposta cutània simpàtica anormal predominantment en les extremitats inferiors. Es va identificar la variant c.1877C> T (p.Ser626Leu) en el gen SAMD9L com el defecte genètic causant de la malaltia. L’estudi també demostrà la localització mitocondrial de la proteïna SAMD9L humana, amb nivells disminuïts en els fibroblasts dels pacients i deficiències mitocondrials i lisosomals en aquest nou subtipus d’atàxia. A més, la sobreexpressió de l’ARNm de SAMD9L mutat humà demostrà deteriorament de la mobilitat i afectació vestibular/sensorial en els embrions del peix zebra. En conclusió, aquest estudi ha identificat els dèficits genètics en el 26,6% dels nostres casos d’atàxia, es demostra la mutació intrònica repetitiva i inestable ATTTC dins el gen DAB1 com la causa genètica subjacent proporcionant evidència de desregulació de la senyalització de reelina- DAB1 en l’atàxia espinocerebel·losa tipus 37, i identifica un nou subtipus d’atàxia espinocerebel·losa causada per la mutació a SAMD9L, que desencadena una desregulació mitocondrial i lisosomal, apuntant al paper de la proteïna SAMD9L en les funcions neurològiques motores i sensorials. Com a resultat d’aquesta tesi, s’aporten nous coneixements sobre els mecanismes clínics, genètics i fisiopatològics subjacents a la neurodegeneració en les atàxies espinocerebel·loses, identificant noves dianes terapèutiques candidates per al tractament.<br>Las ataxias espinocerebelosas (SCAs) consisten en un grupo heterogéneo de trastornos del movimiento hereditarios caracterizados clínicamente por ataxia progresiva asociada de forma variable con otros signos neurológicos adicionales como signos piramidales o extrapiramidales, oftalmoplejía, retinosis pigmentaria, demencia o convulsiones. La heterogeneidad clínica se explica por la heterogeneidad genética, con más de 53 loci y 40 genes identificados asociados hasta la fecha. En esta tesis se ha estudiado una cohorte de 308 pacientes con ataxia, identificando variantes genéticas causativas en 82 casos índice (26,6%), 45 de ellas no descritas previamente.
Durante el curso de esta tesis, nuestro grupo identificó un nuevo subtipo de ataxia, SCA37, y localizó su defecto genético en el cromosoma 1p32. En el presente estudio se ha identificado la mutación intrónica repetitiva e inestable ATTTC dentro de la región reguladora 5’ no codificante del gen Disabled 1 (DAB1) como el defecto genético causante de SCA37. Además, se describe la correlación clínico-genética y los primeros hallazgos neuropatológicos en SCA37 que indican que la enfermedad está causada por la desregulación de la expresión de DAB1 en el cerebelo con pérdida severa de células de Purkinje en la corteza cerebelosa y la presencia de gránulos perisomáticos ubiquitinados e inmunoteñidos para DAB1. Es importante destacar que la repetición ATTTC desregula la expresión del ARN de DAB1 resultando en la sobreexpresión de la ruta de señalización mediada por reelina-DAB1 y PI3K/AKT en el cerebelo SCA37. Por último, pero no menos importante, se han realizado estudios de ligamiento del genoma completo y secuenciación del exoma en una familia de Menorca con siete individuos afectos que presentaban ataxia, nistagmo, disartria, polineuropatía y signos piramidales de forma variable y con una herencia autosómica dominante. La edad de inicio de la enfermedad oscila entre los 15 y 50 años. Las resonancias magnéticas revelaron atrofia cerebelosa con desmielinización cerebral, y los estudios neurofisiológicos mostraron polineuropatía sensitiva axonal moderada con respuesta cutánea simpática anormal predominantemente en las extremidades inferiores. Se identificó la variante c.1877C> T (p.Ser626Leu) en el gen SAMD9L como el defecto genético causante de la enfermedad. El estudio también demuestra la localización mitocondrial de la proteína SAMD9L humana, con niveles disminuidos en fibroblastos de los pacientes, así como deficiencias mitocondriales y lisosomales en este nuevo subtipo de ataxia. Además, la sobreexpresión del ARNm de SAMD9L mutado humano demuestra deterioro de la movilidad y afectación vestibular/sensorial en los embriones del pez cebra.
En conclusión, este estudio ha identificado los déficits genéticos en el 26,6% de nuestros casos de ataxia, demuestra la mutación intrónica repetitiva e inestable ATTTC dentro del gen DAB1 como la causa genética subyacente proporcionando evidencia de la desregulación de la señalización mediada por reelina-DAB1 en la ataxia espinocerebelosa tipo 37, y describe un nuevo subtipo de ataxia espinocerebelosa causada por la mutación SAMD9L, que desencadena una desregulación mitocondrial y lisosomal, apuntando al papel de SAMD9L en las funciones neurológicas motoras y sensoriales. Como resultado de esta tesis, se aportan nuevos conocimientos sobre los mecanismos clínicos, genéticos y fisiopatológicos subyacentes a la neurodegeneración en las ataxias espinocerebelosas, y se identifican nuevas dianas terapéuticas candidatas para el tratamiento.<br>Spinocerebellar ataxias (SCAs) consist of a heterogeneous group of inherited movement disorders clinically characterised by progressive ataxia variably associated with additional neurological signs such as pyramidal or extrapyramidal signs, ophthalmoplegia, pigmentary retinopathy, dementia or seizures. This clinical heterogeneity is explained by its genetic heterogeneity, with more than 53 loci and 40 genes identified and associated to date. In this thesis, a cohort of 308 ataxia patients were studied, finding causative genetic variants in 82 index cases (26.6%), 45 of them previously not described. During the course of this thesis our group identified a novel SCA37 ataxia subtype and localised its genetic defect to chromosome 1p32. The present study identifies the unstable intronic ATTTC repeat mutation within the 5′-non-coding regulatory region of the Disabled 1 gene (DAB1), as the causative genetic defect of SCA37. Moreover, it describes the clinical-genetic correlation and the first neuropathological findings in SCA37 which reveal that the disease is caused by dysregulation of cerebellar DAB1 expression with severe loss of Purkinje cells in the cerebellar cortex, and the presence of ubiquitinated perisomatic granules immunostained for DAB1. Importantly, the ATTTC repeat induced DAB1 RNA switch resulting in the upregulation of reelin-DAB1 and PI3K/AKT signalling in the SCA37 cerebellum. Last but not least, whole-genome linkage and exome studies were performed in a family from Menorca with seven affected individuals variably presenting with ataxia, nystagmus, dysarthria, polyneuropathy and pyramidal signs with an autosomal dominant inheritance. Variable age at onset ranged from 15 to 50 years. MRI revealed cerebellar atrophy with cerebral demyelination, and neurophysiological studies showed moderate axonal sensory polyneuropathy with abnormal sympathetic skin response predominantly in the lower limbs. The c.1877C>T (p.Ser626Leu) variant in the SAMD9L gene was identified as the disease causative genetic defect. The study also demonstrated the mitochondrial location of human SAMD9L protein, with its levels decreased in patients’ fibroblasts and evidenced mitochondrial and lysosomal deficits in this novel ataxia subtype. In addition, overexpression of the human mutated SAMD9L mRNA revealed impaired mobility and vestibular/sensory functions in zebrafish embryos.
In conclusion, this study identifies the genetic deficits in 26.6% of our ataxia cases, demonstrates the unstable ATTTC repeat mutation within the DAB1 gene as the underlying genetic cause providing evidence of reelin-DAB1 signalling dysregulation in the spinocerebellar ataxia type 37, and describes a novel spinocerebellar ataxia subtype caused by SAMD9L mutation, which triggers mitochondrial and lysosomal dysregulation, pointing to the role of SAMD9L in neurological motor and sensory functions. As a result of this thesis novel insights into the clinical, genetic and physiopathological mechanisms underlying neurodegeneration in spinocerebellar ataxias are identified providing new candidate targets for treatment.<br>Universitat Autònoma de Barcelona. Programa de Doctorat en Neurociències
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Samaha, Mahboub Caline. "Logique et Réalité chez Hegel et Aristote. Dialogue avec Adorno et Deleuze." Electronic Thesis or Diss., Poitiers, 2019. http://theses.univ-poitiers.fr/66692/2019-Samaha-Mahboub-Caline-These.
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Dans cette thèse, nous remettons en question la critique faite à l'identité comme étant ce qui opprime la différence et l'évolution. Nous essayons de montrer que la recherche de l'identité propre au système hégélien ne porte pas atteinte au réel mais au contraire l'enrichit et est une condition pour son évolution et pour notre liberté. Nous montrons aussi comment l'accent mis sur l'unité lors de l'interprétation d'un philosophe, ici Aristote, est légitime parce qu'il nous permet de souligner chez lui une contribution à la recherche de la connaissance et de la liberté bien plus que ne le ferait l'accent mis sur la séparation, préservant mystère et irréductibilité. Cette dernière pourrait plutôt nous aliéner tout en nous donnant une illusion de liberté et d'espace. Nous nous opposons donc à une logique de la transcendance et de la séparation nous montrons comment cette logique est en elle-même réductrice. Nos travaux ont ainsi mené plus spécifiquement à assumer les idées d'unité, d'identité et d'achèvement présentes chez Hegel, dans une première partie et à montrer contre Adorno principalement qu'elles ne s'opposent pas à la liberté humaine mais qu'au contraire elles l'impliquent et en sont une condition nécessaire. Nous essayons dans une seconde partie de soutenir une interprétation hégélienne d'Aristote qui tient compte de l'unité, en nous opposant notamment à Pierre Aubenque qui défend chez Aristote une séparation et une irréductibilité. Enfin, dans une dernière partie nous soutenons la représentation du réel à travers la logique, - la contradiction chez Hegel et les contraires chez Aristote - avec pour but de montrer que le négatif propre à la représentation permet un pouvoir effectif sur le réel et ne peut être considéré être illusoire comme le prétendent Deleuze et Nietzsche. Dans ce travail, nous nous servons des critiques que font ces philosophes et ces commentateurs contre la philosophie hégélienne et contre ce qu'elle comprend comme présupposés, identité, système et logique pour mener notre réflexion. En soulignant les contradictions inhérentes à leurs critiques, nous montrons que la philosophie hégélienne et la perspective qu'elle propose dépasse ou surmonte ces contradictions et s'oriente plus vers la liberté<br>In this thesis, we challenge the critique of identity as being what oppresses difference and evolution. We try to show that the search for identity in the Hegelian system does not undermine the real but on the contrary enriches it and is a condition for its evolution and for our freedom. We also show how the emphasis on unity when interpreting a philosopher, here Aristotle, is legitimate because it allows us to emphasize in him a contribution to the search for knowledge and freedom well more than the emphasizing separation and preserving mystery and irreducibility. The latter could rather alienate us while giving us an illusion of freedom and space. We therefore oppose a logic of transcendence and separation, and show how this logic is in itself reductive. Our work has thus led more specifically in a first part to take on the ideas of unity, identity and completion present in Hegel and to show versus Adorno mainly that said ideas do not oppose human freedom but that on the contrary they imply it and are a necessary condition thereof. We try in a second part to support a Hegelian interpretation of Aristotle that takes into account unity, opposing in particular Pierre Aubenque who defends a separation and irreducibility in Aristotle. Finally, in a last part we support the representation of the real through logic - the contradiction in Hegel and the opposites in Aristotle - with the aim of showing that the negative of the representation allows an effective power over the real and cannot be considered illusory as claimed by Deleuze and Nietzsche. In this work, our reflection is led by the criticism made by these philosophers and commentators against the Hegelian philosophy and what it includes in terms of presuppositions, identity, system and logic. By highlighting the contradictions inherent in their criticism, we show that the Hegelian philosophy and the perspective it proposes overcome these contradictions and move towards freedom
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Sameh, Abdel Hadi Ali [Verfasser]. "Die Chelatbildung der dreiwertigen Transplutoniumelemente mit Nitrilotriessigsäure und ihren Derivaten / Abdel Hadi Ali Sameh." Karlsruhe : KIT-Bibliothek, 2008. http://d-nb.info/1186086491/34.
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Pham, Thu Hang. "Molecular biology and biochemistry of the polyamine pathway in rice : the role of SAMDC." Thesis, University of Newcastle Upon Tyne, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275414.
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Dridi, Sameh [Verfasser], Peter [Gutachter] Heine, and Thomas [Gutachter] Zitelmann. "Die Bedeutung der spirituellen Heilung in Tunesien / Sameh Dridi ; Gutachter: Peter Heine, Thomas Zitelmann." Berlin : Humboldt-Universität zu Berlin, 2012. http://d-nb.info/1208079840/34.
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Kung, Jason. "Effects of ionizing radiation on osseous healing in SAMR1 and SAMP6 mice: a histiological study." Thesis, Boston University, 2012. https://hdl.handle.net/2144/12460.
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Thesis (M.A.)--Boston University
PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.<br>Previous studies have showed effects of irradiation on bone and on fracture healing. This is a histological study of the effect of a combined irradiation/fracture injury model in a strain of aged mice (SAMP6) and controls (SAMR1) and the effects of the radioprotective agent, JP4-039 (a mitochondria targeted GS-nitroxide). Hind legs in SAMR1 and SAMP6 control mice and mice pretreated with JP4-039 were exposed to a single dose of radiation (0 or 20 Gy). Twenty four hours after irradiation, unicortical osseous wounds were created in each proximal tibia. Mice were sacrificed at intervals (14, 21 days), tibias excised, radiographed, and prepared for histology (day 21 only). Tibias were examined and graded histologically for evidence of cortical bridging and intramedullary fibrosis. Irradiated SAMP6 wounds showed significantly diminished cortical bridging and significantly more intramedullary fibrosis. In contrast, JP4-039 showed a statistical trend in ameliorating intramedullary fibrosis in irradiated SAMP6 mice. In control SAMR1 mice, JP4-039 had no significant effect on cortical bridging or fibrosis with the number of replicates available. In summary, SAMP6 mice display diminished capacity to recover from the combined irradiation/fracture injury model, with subgroups pretreated with JP4-039 showing beneficial trends in mitigating irradiation induced injury.
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Le?es, Roberta Nascimento. "Desenvolvimento de um sistema para avalia??o de marcha em simula??o de hipogravidade (SAMSH)." Pontif?cia Universidade Cat?lica do Rio Grande do Sul, 2006. http://tede2.pucrs.br/tede2/handle/tede/2995.
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Previous issue date: 2006-03-31<br>Este estudo ? referente ao desenvolvimento de um Sistema de Avalia??o de Marcha em Simula??o de Hipogravidade (SAMSH). Para tal, fez-se necess?rio o aprimoramento de um Sistema de Suspens?o Corporal (SSC) e instrumenta??o de uma esteira el?trica para a constru??o de uma plataforma de movimento como uma t?cnica de locomo??o f?sica em um ambiente virtual. O SAMSH foi testado em um ?nico indiv?duo, pois este estudo n?o objetivou sua valida??o. Foram realizadas an?lises cinem?ticas da marcha de um indiv?duo caminhando sobre uma esteira el?trica em diferentes condi??es de redu??o de peso corporal (30% simulando gravidade Marciana e 60%, Lunar), com e sem a utiliza??o de ?culos de realidade virtual (Head Mounted Display, HMD). Os instrumentos utilizados para o processo de avalia??o foram eletrogoni?meros de joelho e tornozelo, footswitches nas por??es anterior e posterior da regi?o plantar, e cinco c?meras de v?deo. Os resultados mostraram que uma redu??o de peso corporal de 60% (Grupo Lua) altera os par?metros cinem?ticos da marcha, aumentando o Tempo de Passada (TP), o Tempo de Contato (TC), o Comprimento de Passada e o Tempo A?reo (TA) e diminuindo a Cad?ncia da Marcha. Sugerem, igualmente, que em hipogravidade realiza-se menos esfor?o durante o ato de caminhar. A utiliza??o do HMD durante a marcha sobre a esteira permitiu o rastreamento da posi??o da cabe?a do indiv?duo em um espa?o tridimensional, apresentando diferen?as de acordo com cada condi??o de redu??o de peso corporal. Al?m disso, o bloqueio do sistema visual pela transmiss?o de cenas virtuais causou d?ficit da manuten??o do equil?brio postural, o qual foi evidenciado, por exemplo, pela rea??o de extens?o protetora.
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Al-Areqi, Samih Taha Mohammed [Verfasser], and Tiziana [Akademischer Betreuer] Margaria-Steffen. "Semantics-based automatic geospatial service composition / Samih Taha Mohammed Al-Areqi ; Betreuer: Tiziana Margaria-Steffen." Potsdam : Universität Potsdam, 2017. http://d-nb.info/1218402814/34.
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Al-shehabi, Hussein [Verfasser]. "The role of human SAMHD1 in restricting porcine endogenous retroviruses (PERVs) and the innate immune response to PERV infection in human primary immune cells / Hussein Ali Nasser Al-shehabi." Berlin : Freie Universität Berlin, 2020. http://d-nb.info/1215099088/34.
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Al-shehabi, Hussein Ali Nasser [Verfasser]. "The role of human SAMHD1 in restricting porcine endogenous retroviruses (PERVs) and the innate immune response to PERV infection in human primary immune cells / Hussein Ali Nasser Al-shehabi." Berlin : Freie Universität Berlin, 2020. http://d-nb.info/1215099088/34.
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Pereira, Gonçalo Filipe de Almeida. "Estudo de regiões de susceptibilidade para o cancro do cólon e recto familiar do tipo x: análise de genes candidatos e de ganhos/deleções em tumores." Master's thesis, Escola Superior de Saúde Egas Moniz, 2014. http://hdl.handle.net/10400.26/7853.
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Dissertação para obtenção do grau de Mestre em Biologia Molecular em Saúde<br>O cancro do cólon e recto familiar do tipo X (FCCTX) define as famílias que preenchem os critérios de Amesterdão, mas nas quais não é identificada mutação germinal nos genes de reparação de erros de DNA do tipo mismatch (MMR) e cujos tumores não apresentam instabilidade de microsatélites. A sua causa molecular não é ainda conhecida. O presente trabalho teve como objectivo avaliar o envolvimento de genes localizados em duas regiões de susceptibilidade previamente identificadas (13q32-33 e 21q11) e o esclarecimento das perdas de heterozigotia (LOH) frequentes em 13q32-33 em tumores FCCTX, através de uma análise do número de cópias (copy number). Pretendeu-se ainda estudar o gene BMPR1A como gene de susceptibilidade para o FCCTX.
Foi efectuada análise de mutações germinais dos genes HSPA13, SAMSN1 e BMPR1A em 15 indivíduos índex das famílias FCCTX e 2 familiares de uma das famílias. Foi ainda realizada, a nível germinal, a pesquisa de transcritos aberrantes dos genes TEX30 e SAMSN1 e quantificada a expressão destes e do HSPA13 por qPCR em 3 indivíduos índex e 6 familiares de uma das famílias FCCTX. Da mesma forma procedeu-se também ao estudo da expressão diferencial dos transcritos alternativos do gene TPP2. Foi ainda avaliada a eventual patogenicidade de três mutações previamente detectadas no gene SLC10A2.
Não foram detectadas quaisquer mutações nem alterações de expressão potencialmente patogénicas nos genes estudados. As análises in silico e de segregação com a doença sugerem no entanto, uma mutação no gene BMPR1A e duas mutações no gene SLC10A2, para as quais são necessários estudos adicionais para concluir sobre a sua patogenecidade. Um dos transcritos do gene TPP2 apresenta expressão diferencial entre amostras, o que sugere a continuação do seu estudo. A LOH frequente em 13q corresponde a ganho/amplificação.
Em conclusão, o presente estudo exclui os genes localizados em 21q11, HSPA13 e SAMSN1, e em 13q32-33, TEX30, como possíveis genes candidatos para o FCCTX. Não é ainda possível excluir o gene SLC10A2 nem o gene TPP2. Mutações no BMPR1A deverão ser raras em FCCTX. Parece existir um elevado grau de instabilidade genómica em lesões precoces FCCTX com ganhos/amplificações frequentes.
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Pattni, Ramesh. "A psychological understanding of the Yogasūtra of Patañjali (sūtra 1 to 6) with a comparative phenomenology of Samādhi and flow." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:a8e852cf-2efa-4821-b77b-ae3db1b34083.
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Over the past thirty years, academic dialogue on the relationships between science and religion within historical, theological and philosophical contexts has flourished, with the importance of this dialogue being positively expressed. In particular, at the intersection of psychology and religion there is a triple relationship between these domains and in this thesis, we bring the Hindu tradition of Classical Yoga into this discourse, aiming for a psychological understanding of the Yogasutra of Patañjali as the primary text of this tradition. With a 'psychology in religion' perspective we identify key psychological concepts in the first six sutra of the text, explicate and explore its psychological dimension, through referencing with other key sutra or aphorisms in the Yogasutra. With a robust methodology consisting of a hermeneutic and phenomenological based close reading of the text and rigorous conceptual analysis, we construct a detailed model of the mind contextualised within the principles and practice of Yoga. We discuss the modifications and states of the mind, the underlying subliminal factors; the nature of embodiment, identity and subjective experience, and the affective and volitional aspects of the individual, as explicated from the text. In Section Three of this thesis we take a dialogical and comparative approach at the intersection of psychology and religion. Csikszentmihalyi has asserted that there is a close resemblance between Yoga and Flow, the latter being developed within the domain of Western Positive Psychology. We carry out a detailed comparative analysis of the phenomenology of Flow and Samadhi presented within a proposed methodology and framework of dimensions of subjectivity and consciousness, to investigate this claim. Clarifying the conceptual differences, establishing parallels and demonstrating common topographical and functional areas in the two phenomena, opens the possibility for an empirical investigation, which we propose. Finally, we point out the contributions of this study and suggest future directions for research in this field.
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Motumi, N. E. "The implementation of the affirmative action policy in the South African Military Health Service (SAMHS) 1995 - 2000." Diss., Pretoria : [s.n.], 2006. http://upetd.up.ac.za/thesis/available/etd-08282007-150015.
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Radebe, Chrystal. "The mentoring of officers commanding in the SA Military Health Service (SAMHS): a military social work perspective." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/2878.
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Thesis (M Social Work (Social Work))--University of Stellenbosch, 2009.<br>An exploratory research design together with a quantitative research approach were
chosen to determine whether military social workers possess the necessary
knowledge, skills and values to mentor Officers Commanding (OCs) in the South
African Military Health Service (SAMHS). The motivation for this study was based on
questions the researcher asked as to whether there was a link between the methods
in social work intervention processes, supervision and mentoring processes. During
the preliminary investigation, the researcher found that no prior research under this
specific subject was undertaken. The researcher also determined from her role as
consultant to Officers Commanding in the SAMHS, that whereas military social
workers received supervision upon joining the South African National Defence Force
(SANDF), OCs, received no formal mentoring. It was also found that although a
mentoring policy in the Department of Defence (DOD) existed, no evidence existed
that a mentoring programme was implemented in the SAMHS. The goal of the study
is therefore to provide military social workers with a framework of a mentoring
process for Officers Commanding in the SAMHS.
The literature study firstly focused on describing the military social work environment
in which the military social worker is employed, as well as theoretical frameworks that
guide the military social worker’s task. Although more than one theoretical framework
was discussed, the main focus was on the systems theory and ecological
perspective. The work environment of the OC was also included, as well as the
challenges of their functions, tasks and roles in the SAMHS. Primarily, the literature
study explored the knowledge, skills and values of the military social worker and the
mentoring process.
The sample that was selected for this study was 46 military social workers that
represented all the chief military social workers in specialist posts and those with a
higher ranking from Captain to Colonel. A quantitative investigation was undertaken
by means of a questionnaire which was completed in groups in the respective
provinces.
The results of the investigation largely confirmed the findings of the literature study
namely that military social workers do fit the requirements to mentor. These
requirements to mentor were evident in the results of the knowledge, skills and
values of military social workers and their understanding of the parallels between the methods in social work, supervision and the mentoring process. The results gave an
indication of the knowledge, skills and values of military social workers to mentor
Officers Commanding in the SAMHS, and the framework of the mentoring process
and how it relates to the casework, group work and supervision processes in social
work.
The recommendations demonstrated that a central body should be identified to coordinate
and plan a mentoring programme in the SAMHS. The recommendations
also include that the Directorate Social Work should provide clear guidelines on how
military social workers should implement the DOD Mentoring policy, and ensure that
military social workers are trained in staff development methods and its processes.
The recommendations included further research: both quantitative and qualitative
research by means of questionnaires and interviews with OCs, as well as monitoring
and evaluation of the mentoring process. This information will benefit military social
workers in their training as mentors. In implementing these recommendations,
military social workers will be able to contribute significantly to the development of
Officers Commanding in the SAMHS and the profession of social work.
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Hlawatsch, Julia [Verfasser], and Thomas [Akademischer Betreuer] Langmann. "Sterile alpha motif containing 7 (Samd7) is a novel Crx-regulated transcriptional repressor in the retina / Julia Hlawatsch. Betreuer: Thomas Langmann." Regensburg : Universitätsbibliothek Regensburg, 2013. http://d-nb.info/1044754176/34.
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Al-Muqdadi, Sameh Wisam [Verfasser], Broder [Akademischer Betreuer] Merkel, Broder [Gutachter] Merkel, Peter [Gutachter] Udluft, and Volkmar [Gutachter] Dunger. "Groundwater investigation and modeling - western desert of Iraq / Sameh Wisam Al-Muqdadi ; Gutachter: Broder Merkel, Peter Udluft, Volkmar Dunger ; Betreuer: Broder Merkel." Freiberg : Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2012. http://d-nb.info/1220837040/34.
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Vijayaraghavan, Balaje. "Identification and characterization of protein-protein interactions in the nuclear envelope." Doctoral thesis, Stockholms universitet, Institutionen för neurokemi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-148432.
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The nuclear envelope forms the interface between the nucleus and the cytoplasm. The nuclear envelope consists of the two concentric lipid membranes, the nuclear pores and the nuclear lamina. The inner nuclear membrane contains hundreds of unique transmembrane proteins showing high tissue diversity. Mutations of some proteins in the nuclear envelope give rise to a broad spectrum of diseases called envelopathies or laminopathies. In this thesis, I aimed to study the functional organization of the nuclear envelope by identifying and characterizing interactions between the nuclear envelope proteins. For this, we developed a novel method called the Membrane Protein Crosslink Immuno-Precipitation, which enable identification of protein-protein interactions in the nuclear envelope in live cells. We identified several novel interactions of the inner nuclear membrane protein, Samp1, and studied the interaction between the Samp1 and the nuclear GTPase, Ran in detail. Samp1 can bind to Ran and is thus the first known transmembrane Ran binding protein and Samp1 might provide a local binding site for Ran in the inner nuclear membrane. We found that Samp1 also binds to the inner nuclear membrane protein, Emerin and Ran can regulate the Samp1-Emerin interaction in the nuclear envelope. During mitosis, Samp1 distributes in the mitotic spindle. Therefore, we investigated a possible functional role of Samp1 in the mitotic machinery. Samp1 depletion resulted in aneuploid phenotypes, metaphase prolongation and decreased distribution of γ-tubulin and β-tubulin in the mitotic spindle. We found that Samp1 can bind to γ-tubulin, which is essential for the microtubule nucleation and hence for the spindle stability. The new interesting features of Samp1 provide insights on the unforeseen functions of the nuclear envelope proteins.<br><p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.</p>
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Madiba, Thomas Khomotjo. "Evaluation of dental emergency outcomes of the Oral Health Fitness Classification of the South African Military Health Service (SAMHS) in Gauteng - South Africa." Diss., University of Pretoria, 2012. http://hdl.handle.net/2263/30881.
Full textAbstract:
Background: The South African National Defence Force (SANDF) like other Defence Forces of the world, conducts medical classification on their members. This medical classification has, as one of the components, an Oral Health Fitness (OHF) classification which is done according to North Atlantic Treaty Organisation (NATO) standards. The aim of the Oral Health Fitness classification is to standardize dental readiness, assess oral health, prioritize dental care, minimize the number of dental emergencies (DE), and emphasize the importance of good oral health to all active duty and reserve forces. Medical classification is conducted by the South African Military Health Services (SAMHS). Aim: The aim of the study was to evaluate the dental emergency outcomes of the Oral Health Fitness classification of the SAMHS in Area Military Health Unit Gauteng (AMHU GT), South Africa Objectives: To determine dental emergency rate for the SAMHS, analyse the dental emergencies and to make recommendations regarding dental emergencies to the SAMHS Methods: A cross-sectional retrospective record analyses of members of the SANDF that received an OHF classification of 1 and 2 in AMHU GT in 2009. The AMHU GT members were followed up for a year to determine if they developed dental emergencies. Data analysis included frequency tables, chi-square tests and logistic regression analysis. The level of significance was set at p<0.05. Results: The dental emergency rate for AMHU Gauteng was 307/1000 per year. The type of dental emergencies were: 58.5% dental restorations, 13% extractions and related complications, 4.3% crown and bridge, 3.9% emergency root canals, 9.9% recementations, 3.6% denture related problems while other emergencies were 6.8%. Patients were more likely to experience a dental emergency if they were white, female, of OHF 2 classification and older than fifty years of age. Conversely they were least likely to experience a dental emergency if they were black, male, of OHF 1 classification and in the age group 31-40. Conclusion: The dental emergency rate of 307/1000 per year for the SANDF is high compared to military health units from other countries and it was influenced by race, age and gender. The types of dental emergencies were mainly preventable.<br>Dissertation (MChD)--University of Pretoria, 2012.<br>Community Dentistry<br>Unrestricted
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Nishimura, Yasumitsu. "Insufficient IL-2 production from splenic CD4[+] T cells causes impaired cell proliferation and early apoptosis in SAMP1, a strain of senescence-accelerated mouse." Kyoto University, 2002. http://hdl.handle.net/2433/149355.
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Dridi, Sameh [Verfasser], Peter [Akademischer Betreuer] Heine, and Thomas [Akademischer Betreuer] Zitelmann. "Die Bedeutung der spirituellen Heilung in Tunesien : eine aktuelle Untersuchung zur Stellung der tibb rûhânî für die Jugendlichen / Sameh Dridi. Gutachter: Peter Heine ; Thomas Zitelmann." Berlin : Humboldt Universität zu Berlin, Philosophische Fakultät III, 2012. http://d-nb.info/1020663421/34.
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Aparicio, Siegmund Samadhi [Verfasser], Jürgen [Akademischer Betreuer] Scheller, and Lutz [Akademischer Betreuer] Schmitt. "Rezeptor cross-talk und die Rolle der Protein Kinase CK2 in der Signaltransduktion von Zytokinen der Interleukin (IL)-6/IL-12-Familie / Samadhi Aparicio Siegmund. Gutachter: Jürgen Scheller ; Lutz Schmitt." Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2015. http://d-nb.info/1067229175/34.
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Del, Valle i. Macià Jaume. "Estudi de la relació existent entre les alteracions de la barrera hematoencefàlica i la beta-amiloïdosi en el model murí de senescència accelerada i malaltia d'Alzheimer SAMP8." Doctoral thesis, Universitat de Barcelona, 2010. http://hdl.handle.net/10803/1838.
Full textAbstract:
La malaltia d'Alzheimer (MA) es caracteritza per la presència a l'hipocamp i l'escorça de plaques senils de la proteïna β-amilode (Aβ), cabdells neurofibrilars de la proteïna tau hiperfosforilada i pèrdua de sinapsis. La hipòtesi neurovascular de la MA dóna una especial importància a les alteracions de la Barrera Hematoencefàlica (BHE) i els increments de la proteïna β-amilode (Aβ). Els ratolins modificats genèticament són els models animals més utilitzats en la investigació de la MA. Tanmateix, aquests ratolins imiten aspectes de la MA de tipus familiar, on alteracions genètiques predisposen a patir la malaltia. Els ratolins d'edat avançada poden ajudar a discernir la frontera entre l'envelliment normal i el patològic. En aquest context prenen especial rellevància els ratolins amb senescència accelerada SAMP8. Aquesta soca ja ha estat descrita com a model de MA i presenta vàries característiques de la MA com dèficits en l'aprenentatge i la memòria, alteracions emocionals, nivells elevats d'APP i Aβ, patologia neuronal associada a tau, alteracions en el sistema colinèrgic, neurodegeneració i estrès oxidatiu entre d'altres. En aquesta tesi hem investigat: 1-Les alteracions i l'evolució temporal de les modificacions en la integritat de la BHE en escorça i hipocamp de ratolins SAMP8; 2-La presència de dipòsits amiloides en aquests ratolins a les zones cerebrals abans esmentades així com el seu increment amb l'edat i 3-La relació temporal i en la localització de les alteracions de la BHE i els dipòsits d'Aβ d'aquests ratolins. Les conclusions que hem estret són que en ratolins SAMP8: 1- Presenten alteracions de la BHE a partir dels 9 mesos d'edat. 2- Presenten acumulacions d'Aβ a partir de 6 mesos d'edat. 3- Presenten nivells més elevats d'angiopatia amiloïdal cerebral (CAA) a partir dels 3 mesos d'edat. 4- Tots els vasos amb CAA mostren també alteracions de la BHE, tot i que hi ha altres basos amb la BHE alterada sense CAA. 5- No hi ha relació directa entre la localització dels dipòsits amiloides i la localització dels vasos sanguinis, els vasos amb CAA ni amb els vasos amb la BHE alterada.