Academic literature on the topic 'Sercambi'

In his Decameron, Giovanni Boccaccio prescribes storytelling as a means of distraction from the anxieties and suffering associated with the mortifera pestilenza of 1348. Boccaccio pays careful attention to semantics in his work; he confines the discussion of pestilence to the frame tale and avoids evoking the plague thematically, symbolically, and linguistically in the one hundred novelle. This essay examines the power attributed to language in times of epidemic outbreak, in particular, the fear of pronouncing the name of an illness, as if somehow, words possessed the power to make one more susceptible to the malady or to infect. This linguistic aversion to pestilence is analyzed in the story collections of Giovanni Boccaccio, Franco Sacchetti, and Giovanni Sercambi.

Endoplasmic reticulum (ER) calcium homeostasis is disrupted in diverse pathologies, including neurodegeneration, cardiovascular diseases, and diabetes. Temporally defining calcium dysregulation during disease progression, however, has been challenging. Here we describe secreted ER calcium-monitoring proteins (SERCaMPs), which allow for longitudinal monitoring of ER calcium homeostasis. We identified a carboxy-terminal modification that is sufficient to confer release of a protein specifically in response to ER calcium depletion. A Gaussia luciferase (GLuc)–based SERCaMP provides a simple and sensitive method to monitor ER calcium homeostasis in vitro or in vivo by analyzing culture medium or blood. GLuc-SERCaMPs revealed ER calcium depletion in rat primary neurons exposed to various ER stressors. In vivo, ER calcium disruption in rat liver was monitored over several days by repeated sampling of blood. Our results suggest that SERCaMPs will have broad applications for the long-term monitoring of ER calcium homeostasis and the development of therapeutic approaches to counteract ER calcium dysregulation.

The relative mRNA levels corresponding to the different sarcoplasmic/endoplasmic-reticulum Ca2+-ATPase isoforms (SERCA1a, SERCA1b, SERCA2a, SERCA2b and SERCA3) were measured by reverse transcriptase–PCR in rat soleus muscles regenerating after notexin-induced necrosis. The succession of appearance of the different types of SERCA mRNA species in regenerating muscle largely recapitulates those observed during normal ontogenesis. The mRNA levels of the muscle-specific isoforms SERCA1a and SERCA2a became very low on the first and third days after injection of the snake venom. It was only on the fifth day of regeneration that the mRNA of the neonatal variant of the fast-twitch skeletal SERCA1b isoform began to rise, well before the other SERCA transcripts. At 7 and 10 days, i.e. at a time when the new myofibres normally become re-innervated, the mRNA level of SERCA1a and SERCA2a increased markedly, but the fast-twitch skeletal SERCA1a isoform was still the most prominent. On day 21, in the advanced stage of regeneration, a switch in the relative expression levels of SERCA1a and SERCA2a mRNA was observed and the ratio of both isoforms became similar to that found in the normal soleus muscles. This was followed by a decline in the level of all SERCA mRNA species, so that on day 28 the levels of the sarcoplasmic/endoplasmatic-reticulum Ca2+-pump RNAs was again lower but their ratio remained similar to that of the untreated control soleus.

Vascular smooth muscle cells (VSMC) express three isoforms of the sarcoplasmic or endoplasmic reticulum Ca2+-ATPase (SERCA) pump; SERCA2b predominates (91%), whereas SERCA2a (6%) and SERCA3 (3%) are present in much smaller amounts. Treatment with thapsigargin (Tg) or A-23187 increased the level of mRNA encoding SERCA2b four- to fivefold; SERCA3 increased about 10-fold, whereas SERCA2a was unchanged. Ca2+ chelation prevented the Tg-induced SERCA2b increase, whereas Ca2+ elevation itself increased SERCA2b expression. These responses were discordant with those of 78-kDa glucose-regulated protein/immunoglobulin-binding protein (grp78/BiP), an endoplasmic reticulum stress-response protein. SERCA2b mRNA elevation was much larger than could be accounted for by the observed increase in message stability. The induction of SERCA2b by Tg did not require protein synthesis, nor was it affected by inhibitors of calcineurin, protein kinase C, Ca2+/calmodulin-dependent protein kinase, or tyrosine protein kinases. Treatment with the nonselective protein kinase inhibitor H-7 prevented Tg-induced SERCA2b expression from occurring, whereas another nonselective inhibitor, staurosporine, was without effect. We conclude that changes in cytosolic Ca2+ control the expression of SERCA2b in VSMC via a mechanism involving a currently uncharacterized, H-7-sensitive but staurosporine-insensitive, protein kinase.

Ca(2+)-uptake experiments in microsomal fractions from transfected COS-1 cells have revealed a functional difference between the non-muscle SERCA2b Ca2+ pump and its muscle-specific SERCA2a splice variant. Structurally, the two pumps differ only in their C-terminal tail. The last four amino acids of SERCA2a are replaced in SERCA2b by a 49-residue-long peptide chain containing a very hydrophobic stretch which could be an additional transmembrane segment. The functionally important subdomains in the SERCA2b tail were analysed by constructing three SERCA2b deletion mutants lacking 12, 31 or 49 amino acids. The mutants and the parental SERCA2 pumps were expressed in COS-1 cells and analysed for functional difference. SERCA2b had a twofold higher Ca2+ affinity, a twofold lower turnover rate and a 10-fold lower vanadate-sensitivity than SERCA2a and the mutants. Since each of the three truncated versions of SERCA2b acquire the characteristic properties of SERCA2a, it is concluded that the stretch of the last 12 residues of SERCA2b is of critical importance.

Sarco/endoplasmic reticulum Ca2+ ATPase (SERCA) pumps Ca2+ from the cytosol into the ER and maintains the cellular calcium homeostasis. Herein, we present cryo–electron microscopy (cryo-EM) structures of human SERCA2b in E1∙2Ca2+–adenylyl methylenediphosphonate (AMPPCP) and E2-BeF3− states at 2.9- and 2.8-Å resolutions, respectively. The structures revealed that the luminal extension tail (LE) characteristic of SERCA2b runs parallel to the lipid-water boundary near the luminal ends of transmembrane (TM) helices TM10 and TM7 and approaches the luminal loop flanked by TM7 and TM8. While the LE served to stabilize the cytosolic and TM domain arrangement of SERCA2b, deletion of the LE rendered the overall conformation resemble that of SERCA1a and SERCA2a and allowed multiple conformations. Thus, the LE appears to play a critical role in conformational regulation in SERCA2b, which likely explains the different kinetic properties of SERCA2b from those of other isoforms lacking the LE.

We have demonstrated previously that Bcl-2 and Bcl-2Δ21, a C-terminally truncated Bcl-2 sequence, inactivate SERCA (sarcoplasmic/endoplasmic reticulum Ca2+-ATPase) 1 in isolated SR (sarcoplasmic reticulum), accompanied by a translocation from CRDs (caveolae-related domains) of the SR. In the present study, we obtained evidence for the interaction of Bcl-2 with SERCA2b in C2C12 myoblasts and HEK (human embryonic kidney)-293 cells. Bcl-2 and SERCA2b co-immunoprecipitated from lysate and microsomal fractions of Bcl-2-overexpressing cells. However, Bcl-2 overexpression resulted only in a slight translocation from the CRDs and no significant SERCA inactivation. In isolated HEK-293 cell microsomes, incubation with Bcl-2Δ21 afforded SERCA2b inactivation and some translocation. HSP (heat-shock protein) 70, HSP90, HSP27 and α-crystallin attenuated Bcl-2Δ21-dependent SERCA2b inactivation. An in vitro mechanistic study with the SERCA1 isoform shows that HSP70 (i) protects SERCA1 from the inactivation by Bcl-2Δ21, (ii) inhibits SERCA1 translocation from CRD fractions, and (iii) prevents the Bcl-2Δ21-dependent loss of FITC labelling. Our data demonstrate that the mechanism of SERCA inactivation by Bcl-2 established in vitro for the SERCA1 isoform can be extended to the main housekeeping SERCA2b isoform, and that functional interactions of SERCA2b and Bcl-2 in the cell may be modulated by HSP70 and other chaperones and stress-regulated proteins.

Maintaining a high Ca(2+) concentration in the lumen of the endoplasmic reticulum (ER), by the action of sarco/endoplasmic reticulum Ca(2+)-ATPases (SERCAs), is important in many cellular processes, such as Ca(2+)-mediated cytosolic signaling in response to extracellular stimuli, cell growth and proliferation, and synthesis, processing and folding of ER-translated proteins. In the thyroid gland, SERCAs have not been studied yet, and there is little information available on general problems such as the expression of SERCAs following neoplastic transformation. In this study we investigated the expression of SERCA2b and SERCA3 in rat thyroid tIssue and, in addition, in normal and transformed rat thyroid cell lines. RT-PCR and Northern blot assays showed that SERCA2b is the SERCA form preferentially expressed in the thyroid. In rat thyroid, SERCA2b mRNA was expressed at a higher level than that of other non-muscle tIssues such as liver or spleen, but at much lower level than in brain. On the other hand, SERCA3 mRNA was not detected in thyroid by Northern blot analysis, or barely detected by RT-PCR assays. We also studied the SERCA2b expression pattern in PC Cl3 thyroid cells transformed by several oncogenes that induce different degrees of malignancy and dedifferentiation. RT-PCR and Northern blot assays showed that SERCA2b mRNA expression dramatically decreased in highly tumorigenic thyroid cells, while expression of glyceraldehyde-3-phosphate dehydrogenase mRNA, a housekeeping gene used as internal control, exhibited no variations. The dramatic down-regulation of SERCA2b expression in fully transformed thyroid cells was also evident by Western blot analysis. Also, following neoplastic transformation of thyroid cells, the enzymatic activity of SERCA2b was reduced in a measure which correlated with the mRNA and protein levels. Therefore, rat thyrocytes expressed intermediate levels of SERCAs, mostly the SERCA2b isoform. This pattern of expression was basically reproduced in fully differentiated thyroid cells in culture and was sensitive to neoplastic transformation.

COS 1 cells were transfected with full-length pig stomach sarcoplasmic/endoplasmic reticulum Ca2+ pump (SERCA)2a or SERCA2b cDNA. Ca2+ uptake by microsomes from transfected cells revealed that the Ca2+ affinity of the SERCA2b Ca2+ pump (K0.5 0.17 +/- 0.01 microM) was higher than that of the SERCA2a Ca2+ pump (K0.5 0.31 +/- 0.02 microM). Thapsigargin-sensitivity was found to be identical for the two isoforms. The Ca2+ affinity of both the SERCA2a and SERCA2b Ca2+ pumps was decreased by a factor of two when they were co-expressed with phospholamban.

This thesis traces the relationship between ‘recounting History’ and ‘re-counting Fiction’ through the analysis of the Croniche di Lucca and the Novelle by Giovanni Sercambi of Lucca (1345-1424). With the rise of literacy, vernacu-lar chronicles and collections of short-stories became increasingly popular among non-literati people, who had not received a formal education and could not read Latin, and consequently showed a marked preference for the fruition of stories in their native tongue. Scholars have already addressed a number of peculiarities that characterize the two works in question. In this thesis the point of view of Sercambi as author, as well as that of his contemporary audience, will be put under the lens. The key argument of the thesis is that Sercambi used the genre of the short story with the intent of shrouding historical facts with a veil of fictional narrative. He was aware that the choice of story-telling represented an alternative and effective vehicle for the transmission of political messages to those Lucchese citizens who read and listened to his stories being read out at Paolo Guinigi’s court. In his short stories Sercambi used the names and circumstances of real Lucchese people for the characterization of a number of personages. Through the examination of untapped archival sources that cast considerable light on Sercambi’s highly personalized approach to narrative, the thesis represents a first attempt to highlight Sercambi’s original contribution to the tradition of the Italian short story. It emerges from this research that Sercambi appears to have achieved a virtuous compromise by being able to mention Paolo Guinigi’s shortcomings as a ruler of Lucca, while at the same time exploring an alternative mode of writing about Lucca’s political and moral decay.

"Le décor de cette recherche est le "contado" florentin à la fm du Moyen Âge. La base de notre documentation repose sur les sources "subjectives" que sont par exemple les "ricordanze", complétées par des sources "objectives" telles que les statuts communaux ou les inventaires de biens ayant appartenu à des paysans. Après avoir consacré un premier chapitre à ces deux auteurs essentiels pour nous que sont Giovanni Sercambi et Franco Sacchetti, nous avons entrepris î'étude de l'image du "vilain" dans la narrative toscane. Un troisième chapitre porte sur le paysage rural, façonné par les paysans du "contado" qui semblent souvent se conformer aux conseils des meilleurs agronomes de leur temps, Piero de'Crescenzi et Michelangelo Tanaglia. Il convient alors de voir la preuve de l'importance que prennent alors les campagnes dans la vie des Florentins. Nous leur avons à notre tour consacré un chapitre. Puis dans la dernière partie de notre travail, c'est la société paysanne dans ses aspects privés que nous avons choisi d'étudier. Indubitablement la documentation nous renseigne sur ce qu'à pu être la vie des paysans au quotidien. Il n'empêche que leurs témoignages directs sont absents d'où la difficulté d'une recherche qui ne perçoit les réalités rurales principalement que d'un côté, celui des possédants urbains. "
The background to this research is the Florentine "contado" of the Late Middle Ages. Our primary source are "subjective" ones such as "ricordanze" backed up by such "objective" sources as village statutes and inventories of peasants' goods and chattels. After a first chapter which deals with the two most important authors, to our mind, Giovanni Sercambi and Franco Sacchetti, we have studied the image of the "villein" in Tuscan narratives. A third chapter deals with rural landscape as shaped by the peasants of the "contado" who often seem to follow the advice of the best agronomists of their time, Piero de'Crescenzi and Michelangelo Tanaglia. A further chapter brings out the important role of the countryside in Florentine life. The final part of our study deals with the private aspects of peasant society. There is no doubt that our sources provide information on the everyday life of peasants, but direct accounts are lacking. Hence the major difficulty of a study which can only see rural reality from one point of view, that of the city dwelling landowner

Abstract The delta opioid receptor (δOR) is a member of the G protein-coupled receptor family. This transmembrane receptor has an important role in the regulation of pain. The OPRD1 gene that encodes the human δOR (hδOR) contains at least 11 single-nucleotide polymorphisms (SNPs). The only nonsynonymous SNP resides in the amino-terminal (N-terminal) domain of the receptor and it replaces Phe at position 27 with Cys, thus introducing an unpaired Cys residue on the extracellular surface of the receptor. The Cys27 variant has been shown to have an allelic frequency of about 10% in Caucasian populations. The polymorphic site is flanked by two putative N-glycosylation sites at Asn18 and Asn33. In this study, the folding, maturation and trafficking of hδOR was assessed using the hδORPhe27 and hδORCys27 variants and the N-glycosylation deficient forms of the latter as models in a heterologous expression system. The effects of N-glycosylation and the unpaired Cys-residue were studied with various biochemical, pharmacological and cell biological methods. In addition, protein-protein interactions of the intracellular hδOR precursors were assessed. The hδORCys27 and hδORPhe27 variants differed significantly in their subcellular localization and maturation efficiency. The newly synthesized hδORCys27 was found to accumulate in the endoplasmic reticulum (ER) prior to its ER-associated degradation in proteasomes. Although a slow maturation rate was characteristic for both variants, only the hδORCys27 had poor maturation efficiency. The cell surface expression of hδORCys27 was further decreased because the constitutive internalization of this receptor was enhanced compared to hδORPhe27. N-linked glycosylation was not required for hδOR function or ligand binding, but was important for the expression of the correctly folded receptor species at the cell surface. The mutant non-N-glycosylated receptor was shown to traffic to the cell surface with enhanced kinetics, but some of the plasma membrane receptors were in a nonnative conformation. Also, the overall levels of the non-N-glycosylated hδORCys27 were decreased as the receptor was efficiently internalized for lysosomal degradation in a constitutive fashion. The hδORCys27 and hδORPhe27 precursors were found to interact with several ER localized proteins, such as calnexin (CNX), protein disulfide isomerase (PDI) and ERp72. The receptors also associated with the sarco(endo)plasmic reticulum calcium ATPase 2b (SERCA2b), which was shown to occur during translocation of the receptor to the ER membrane or immediately thereafter. The interaction was not receptor N-glycan dependent and the normal functional activity of SERCA2b was shown to be required for proper cell surface expression of hδOR
Tiivistelmä δ-opioidireseptori kuuluu G-proteiinikytkentäisiin reseptoreihin, ja sillä on tärkeä rooli kivun säätelyssä. Ihmisen δ-opioidireseptoria koodaavassa OPRD1 geenissä on havaittu ainakin 11 yhden nukleotidin polymorfiaa. Vain yksi tunnetuista polymorfioista aiheuttaa muutoksen proteiinin aminohapposekvenssiin. Se sijaitsee reseptorin aminoterminaalisessa osassa ja se muuttaa fenyylialaniinin (Phe) kohdassa 27 kysteiiniksi (Cys), joka on pariton. Cys27-variantin yleisyys eurooppalaisessa väestössä on noin 10 %. Polymorfisen kohdan molemmilla puolilla on N-glykosylaatiokohdat asparagiineissa Asn18 ja Asn33. Tämän työn tavoitteena oli tutkia δ-opioidireseptorin laskostumista, maturaatiota ja kuljetusta heterologisessa solumallissa käyttämällä Phe27- ja Cys27-variantteja sekä Cys27-variantin N-glykosyloimatonta mutanttia. Cys27-polymorfian ja N-glykosylaation vaikutuksia tutkittiin useilla biokemiallisilla, farmakologisilla sekä solubiologisilla menetelmillä. Lisäksi työssä tutkittiin solunsisäisen δ-opioidireseptorin esiasteen vuorovaikutusta muiden proteiinien kanssa. Phe27- ja Cys27-varianttien sijainti solun sisällä ja maturaatiotehokkuus eroavat toisistaan merkittävästi. Vastasyntetisoitu Cys27-variantti kerääntyy endoplasmakalvostoon, josta se ohjautuu proteasomihajoitukseen. Molemmat variantit kulkeutuvat solun pintaan hitaasti. Cys27-variantin prosessointi on huomattavasti tehottomampaa ja sen määrää solun pinnalla vähentää myös lisääntynyt ohjaaminen solunsisäiseen lysosomihajotukseen. N-glykosylaatiolla ei havaittu olevan vaikutusta reseptorin toimintaan tai ligandin sitomiseen, mutta sillä on tärkeä merkitys oikein laskostuneiden reseptorien kuljetukselle solun pinnalle, koska osa pintaan päässeistä N-glykosyloimattomista reseptoreista on muodossa, johon reseptorispesifinen ligandi ei sitoudu. Vaikka mutanttireseptori kulkeutuukin solun pintaan nopeammin, sen määrä solun pinnalla on alhaisempi, koska mutanttireseptori ohjataan huomattavan nopeasti solun pinnalta lysosomihajotukseen. Phe27- ja Cys27-varianttien havaittiin olevan myös vuorovaikutuksessa eräiden endosomaalisen kalvoston proteiinien kanssa, kuten kalneksiinin, proteiinidisulfidi-isomeraasin ja ERp72-proteiinin. Kumpikin reseptori havaittiin yhteisessä rakenteessa sarko(endo)plasmakalvoston kalsium-ATPaasi 2b -pumpun (SERCA2b) kanssa N-glykosylaatiosta riippumattomalla tavalla. Nämä proteiiniryhmät muodostuvat, kun reseptori liitetään synteesin aikana endoplasmakalvostoon tai heti sen jälkeen. Vuorovaikutus toiminnallisen SERCA2b:n kanssa havaittiin tärkeäksi toimintakykyisen δ-opioidireseptorin esiintymiselle solun pinnassa

Le transfret de calcium (Ca2+) entre le réticulum endoplasmique (RE) et la mitochondrie est médié par des sites de contact dynamiques. Nous avons montré que l'isoforme tronquée de la SERCA1 (S1T) ignitie et amplifie la voie pro-apoptotique du stress du RE. De plus, elle détermine une fuite localisée du Ca2+ au niveau des sites de contacts RE-mitochondrie induisant l'apoptose. Nous avons également montré que S1T est surexprimée dans la maladie d'Alzheimer. Parallèlement, l'Aβ s'accumule au niveau des sites de contact RE-mitochondrie. Par ailleurs, l'analyse de la signalisation calcique subcellulaire nous a permis de démontrer une dérégulation majeure de celle-ci. Enfin, nous avons révélé que le Ca2+ contrôle les processus bioénergétiques altérés dans la maladie de Leigh due au déficit du complexe II de la chaîne respiratoire mitochondriale. Nos résultats ont mis en évidence l'impact du transfert du Ca2+ entre le RE et la mitochondrie dans les pathologies du RE et de la mitochondrie
Calcium (Ca2+) transfer between endoplasmic reticulum (ER) and mitochondria is mediated through dynamic contacts sites. We showed that the truncated isoform of SERCA1 (S1T) initiates and simplifies the proapoptotic pathway of the ER stress signaling. In addition, owing to its localization at the ER-mitochondria contacts sites, it determines a localized ER Ca2+ leak towards the mitochondria leading to mitochondrial apoptosis. We also demonstrated that S1T is overexpressed in Alzheimer's disease. In parallel, Aβ accumulates in ER-mitochondria contact sites. In addition, an extensive analysis of subcellular Ca2+ signaling allowed us to demonstrate its drastic deregulation. Lastly, we have revealed that Ca2+ control bioenergetics pathways in Leigh's disease related to mitochondrial respiratory chain complex II deficiency. Our results showed the impact of Ca2+ transfer from ER to mitochondria-related pathologies

Indiana University-Purdue University Indianapolis (IUPUI)
Diabetes mellitus affects an estimated 285 million people worldwide, and a central component of diabetes pathophysiology is diminished pancreatic islet beta cell function resulting in the inability to manage blood glucose effectively. The beta cell is a highly specialized metabolic factory that possesses a number of specialized characteristics, chief among these a highly developed endoplasmic reticulum (ER). The sarco endoplasmic reticulum Ca2+ ATPase 2b (SERCA2b) pump maintains a steep Ca2+ gradient between the cytosol and ER lumen, and while the Pancreatic and duodenal homeobox 1 (Pdx-1) transcription factor is known to play an indispensable role in beta cell development and function, recent data also implicate Pdx-1 in the maintenance of ER health. Our data demonstrates that a decrease of beta cell Pdx-1 occurs in parallel with decreased SERCA2b expression in models of diabetes, while in silico analysis of the SERCA2b promoter reveals multiple putative Pdx-1 binding sites. We hypothesized that Pdx-1 loss under inflammatory and diabetic conditions leads to decreased SERCA2b with concomitant alterations in ER health. To test this, siRNA-mediated knockdown of Pdx-1 was performed in INS-1 cells. Results revealed reduced SERCA2b expression and decreased ER Ca2+, which was measured using an ER-targeted D4ER adenovirus and fluorescence lifetime imaging microscopy. Co-transfection of human Pdx-1 with a reporter fused to the human SERCA2 promoter increased luciferase activity three-fold relative to the empty vector control, and direct binding of Pdx-1 to the proximal SERCA2 promoter was confirmed by chromatin immunoprecipitation. To determine whether restoration of SERCA2b could rescue ER stress induced by Pdx-1 loss, Pdx1+/- mice were fed high fat diet for 8 weeks. Isolated islets from these mice demonstrated increased expression of spliced Xbp1, signifying ER stress, while subsequent SERCA2b overexpression in isolated islets reduced spliced Xbp1 levels to that of wild-type controls. These results identify SERCA2b as a direct transcriptional target of Pdx-1 and define a novel role for altered ER Ca2+ regulation in Pdx-1 deficient states.