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Littérature scientifique sur le sujet « Fc��RIIA »
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Articles de revues sur le sujet "Fc��RIIA"
1
Astier, A., H. de la Salle, C. de la Salle, T. Bieber, M. E. Esposito-Farese, M. Freund, J. P. Cazenave, W. H. Fridman, J. L. Teillaud et D. Hanau. « Human epidermal Langerhans cells secrete a soluble receptor for IgG (Fc gamma RII/CD32) that inhibits the binding of immune complexes to Fc gamma R+ cells. » Journal of Immunology 152, no 1 (1 janvier 1994) : 201–12. http://dx.doi.org/10.4049/jimmunol.152.1.201.
Texte intégralRésumé :
Abstract Langerhans cells (LC) express Fc gamma RII on their cell surface. In this paper, we demonstrate that these cells also release soluble Fc gamma RII (sFc gamma RII) molecules. LC express transcripts encoding a membrane-associated receptor and a transmembrane-deleted Fc gamma RIIA. The latter form was identified in LC culture supernatants using specific antibodies. CHO cells, transfected with LC-derived cDNA encoding the transmembrane-deleted Fc gamma RIIA, secrete sFc gamma RIIA that include the intracellular domain and exhibit the same backbone as the protein identified in LC supernatants. Secreted sFc gamma RIIA exhibits the same pattern of binding to human and mouse IgG subclasses as do membrane Fc gamma RII and inhibits the binding of immune complexes to Fc gamma RII+ cells. In addition, CHO cells expressing the membrane-associated Fc gamma RIIA release truncated and unstable Fc gamma RIIA molecules that lack the intracellular domain. Thus, sFc gamma RII can result from shedding of membrane molecules and/or from secretion of soluble receptors lacking the transmembrane domain.
2
Yanaga, F., A. Poole, J. Asselin, R. Blake, G. L. Schieven, E. A. Clark, C. L. Law et S. P. Watson. « Syk interacts with tyrosine-phosphorylated proteins in human platelets activated by collagen and cross-linking of the Fc γ-IIA receptor ». Biochemical Journal 311, no 2 (15 octobre 1995) : 471–78. http://dx.doi.org/10.1042/bj3110471.
Texte intégralRésumé :
Activation of human platelets by cross-linking of the platelet low-affinity IgG receptor, the Fc gamma receptor IIA (Fc gamma-RIIA), or by collagen is associated with rapid phosphorylation on tyrosine of the non-receptor tyrosine kinase syk. Phosphorylation is still observed, albeit sometimes reduced, in the presence of a combination of a protein kinase C inhibitor, Ro 31-8220, and the intracellular calcium chelator, BAPTA-AM, demonstrating independence from phosphoinositide-specific phospholipase C (PLC) activity. In contrast, the combination of Ro 31-8220 and BAPTA-AM completely inhibits phosphorylation of syk in thrombin-stimulated platelets. Phosphorylation of syk increases its autophosphorylation activity measured in a kinase assay performed on syk immunoprecipitates. Fc gamma-RIIA also undergoes phosphorylation in syk immunoprecipitates from platelets activated by cross-linking of Fc gamma-RIIA but not by collagen, suggesting that it associates with the kinase. Consistent with this, tyrosine-phosphorylated Fc gamma-RIIA is precipitated by a glutathione S-transferase (GST) fusion protein containing the tandem src homology (SH2) domains of syk from Fc gamma-RIIA- but not collagen-activated cells. Two uncharacterized tyrosine-phosphorylated proteins of 40 and 65 kDa are uniquely precipitated by a GST fusion protein containing the tandem syk-SH2 domains in collagen-stimulated platelets. A peptide based on the antigen recognition activation motif (ARAM) of Fc gamma-RIIA, and phosphorylated on the two tyrosine residues found within this region, selectively binds syk from lysates of resting platelets; this interaction is not seen with a non-phosphorylated peptide. Kinase assays on Fc gamma-RIIA immunoprecipitates reveal the constitutive association of an unidentified kinase activity in resting cells which phosphorylates a 67 kDa protein. Syk is not detected in Fc gamma-RIIA immunoprecipitates from resting cells but associates with the receptor following activation and, together with Fc gamma-RIIA, is phosphorylated in the kinase assay in vitro. These results demonstrate that syk is activated by Fc gamma-RIIA cross-linking and collagen, independent of PLC, suggesting that it may have an important role in the early events associated with platelet activation. The association of syk with Fc gamma-RIIA appears to be mediated through the tandem SH2 domains in syk and the ARAM motif of Fc gamma-RIIA. A similar interaction may underlie the response to collagen, suggesting that its signalling receptor contains an ARAM motif.
3
Warmerdam, P. A., J. G. van de Winkel, A. Vlug, N. A. Westerdaal et P. J. Capel. « A single amino acid in the second Ig-like domain of the human Fc gamma receptor II is critical for human IgG2 binding. » Journal of Immunology 147, no 4 (15 août 1991) : 1338–43. http://dx.doi.org/10.4049/jimmunol.147.4.1338.
Texte intégralRésumé :
Abstract The low-affinity human Fc gamma RIIa is encoded by a single gene with allelic variation, defined by low-responder and high-responder alleles (LR and HR). The HR Fc gamma RIIa transcript interacts strongly with murine (m) IgG1 complexes, in contrast to the LR Fc gamma RIIa. Furthermore, the transcripts can be discriminated by mAb 41H16, which recognizes an epitope expressed on the HR Fc gamma RIIa molecule. We report that this receptor is also polymorphic in its reactivity with human (h) IgG2. Binding studies using well-defined hIgG dimers revealed that LR Fc gamma RIIa molecules can efficiently bind hIgG2, in contrast to HR Fc gamma RIIa. Previous work of others showed one amino acid difference between the allelic forms of Fc gamma RII. We, however, found a second amino acid difference between both allelic forms. In this study, hybrid Fc gamma RIIa molecules were constructed to determine the epitope for mAb 41H16 and the binding domain for mIgG1 and hIgG2 complexes. Our data point to the importance of the amino acid at position 131, located in the second Ig-like domain of Fc gamma RIIa. When an arginine residue is present at amino acid position 131, the receptor is recognized by mAb 41H16. Furthermore, the receptor can bind mIgG1-sensitized indicator E, but binds hIgG2 dimers only weakly. When a histidine residue is present at this amino acid position, hIgG2 dimers do bind efficiently to Fc gamma RII, whereas mIgG1-sensitized E and mAb 41H16 exhibit a strongly diminished binding.
4
Van den Herik-Oudijk, IE, PJ Capel, T. van der Bruggen et JG Van de Winkel. « Identification of signaling motifs within human Fc gamma RIIa and Fc gamma RIIb isoforms ». Blood 85, no 8 (15 avril 1995) : 2202–11. http://dx.doi.org/10.1182/blood.v85.8.2202.bloodjournal8582202.
Texte intégralRésumé :
To assess the functional capacity of the heterogeneous Fc gamma RII (CD32) family and to identify critical regions for functioning, we generated a panel of B-cell transfectants. The Fc gamma R-negative B-cell line IIA1.6 was transfected with wild-type or mutant human Fc gamma RIIa and IIb molecules. Solely Fc gamma RIIa-expressing IIA1.6 cells were capable of phagocytosing opsonized Staphylococcus aureus bacteria, and cross-linking of Fc gamma RIIa triggered a rapid induction of tyrosine phosphorylation after 20 seconds. Analysis of Fc gamma RIIa mutants identified the immunoreceptor tyrosine-based activation motif (ITAM; previously described as ARH-1 motif) within the IIa cytoplasmic tail to be critical for B-cell activation. In contrast, Fc gamma RIIb isoforms triggered tyrosine phosphorylation on cross-linking with much slower kinetics (> 3 minutes) than Fc gamma RIIa. Furthermore, solely Fc gamma RIIb molecules proved capable of downregulating [Ca2+]i and interleukin-2 production on co-cross-linking with sIgG in IIA1.6. The Fc gamma RIIb-mediated functions were absent in Fc gamma RIIb mutants in which the tyrosine or leucine within the YSLL motif in a conserved 13-aa region (now known as immunoreceptor tyrosine-based inhibitor motif [ITIM]) were changed into phenylalanines. In conclusion, these data show the presence of functionally critical motifs within Fc gamma RII cytoplasmic tails. Fc gamma RIIa contains an ITAM involved in B-cell activatory functions, whereas the downregulatory activity of Fc gamma RIIb isoforms is linked to an ITIM.
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Van den Herik-Oudijk, IE, MW Ter Bekke, MJ Tempelman, PJ Capel et JG Van de Winkel. « Functional differences between two Fc receptor ITAM signaling motifs ». Blood 86, no 9 (1 novembre 1995) : 3302–7. http://dx.doi.org/10.1182/blood.v86.9.3302.bloodjournal8693302.
Texte intégralRésumé :
Most Ig receptors exist as multi-subunit complexes with a unique ligand binding alpha chain and a common signaling FcR gamma-chain. The myeloid Fc gamma RIIa (CD32) appears unique among FcR because both ligand- binding and signaling capacity are found in the alpha chain. Within the cytoplasmic tails of Fc gamma RIIa and FcR gamma-chain similar, but not identical, activatory motifs (ITAMs) have been defined, in which tyrosines play an important role. Previously, Fc gamma RIIa-ITAM was shown to be critical for both proximal and distal activatory functions in IIA1.6 B-cell transfectants. Triggering of interleukin-2 (IL-2) release and antigen presentation was absent in Fc gamma RIIa, but not in FcR gamma-chain receptor complexes. We now assessed the capacity of Fc gamma RIIa wild-type and Fc gamma RIIa/gamma chimeric molecules to trigger IL-2 production and antigen presentation by B cells. Both of these functions could solely be triggered by receptors containing the FcRIIa was capable of functional interaction with FcR gamma-chain, thus reconstituting the capacity to trigger IL-2 release and antigen presentation. These data document qualitative differences between Fc receptor ITAMs.
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Indik, ZK, XQ Pan, MM Huang, SE McKenzie, AI Levinson et AD Schreiber. « Insertion of cytoplasmic tyrosine sequences into the nonphagocytic receptor Fc gamma RIIB establishes phagocytic function ». Blood 83, no 8 (15 avril 1994) : 2072–80. http://dx.doi.org/10.1182/blood.v83.8.2072.2072.
Texte intégralRésumé :
Abstract Receptors for the Fc domain of IgG on cells of hematopoietic lineage perform important functions, including stimulation of the ingestion of IgG-coated cells. In examining the function of Fc gamma receptor isoforms by transfection into COS-1 cells, we have observed that Fc gamma RIIA induces the binding and phagocytosis of IgG-sensitized RBCs (EA) and that transfected COS-1 cells can serve as a model for examining the molecular structures involved in mediating a phagocytic signal. We now report that COS-1 cell transfectants expressing the isoforms Fc gamma RIIB1 and Fc gamma RIIB2 and a Fc gamma RIIA mutant without a cytoplasmic tail efficiently bind EA but do not mediate their phagocytosis. Furthermore, wild-type Fc gamma RIIA, but not Fc gamma RIIB1 or Fc gamma RBII2, was phosphorylated on tyrosine upon receptor activation. Tyrphostin 23, which alters tyrosine kinase activity, inhibited the phagocytosis of EA and reduced the phosphorylation of Fc gamma RIIA on tyrosine. Fc gamma RIIB1 and Fc gamma RIIB2 contain one copy of the cytoplasmic sequence YXXL/I implicated in signal transduction, whereas Fc gamma RIIA contains two copies. We therefore inserted YXXL/I sequences at different sites in Fc gamma RIIB2. Low levels of phagocytosis were observed in a Fc gamma RIIB2 mutant bearing the Fc gamma RIIA sequence YMTL and higher levels of phagocytosis were observed in a second Fc gamma RIIB2 mutant that contained both the upstream YMTL and an additional downstream tyrosine-containing motif. Activation of this mutant receptor also induced receptor tyrosine phosphorylation. Thus, these studies indicate that both the number and placement of YXXL sequences in the cytoplasmic domain of the Fc gamma RII receptor family affect both receptor tyrosine phosphorylation and phagocytic competence.
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Indik, ZK, XQ Pan, MM Huang, SE McKenzie, AI Levinson et AD Schreiber. « Insertion of cytoplasmic tyrosine sequences into the nonphagocytic receptor Fc gamma RIIB establishes phagocytic function ». Blood 83, no 8 (15 avril 1994) : 2072–80. http://dx.doi.org/10.1182/blood.v83.8.2072.bloodjournal8382072.
Texte intégralRésumé :
Receptors for the Fc domain of IgG on cells of hematopoietic lineage perform important functions, including stimulation of the ingestion of IgG-coated cells. In examining the function of Fc gamma receptor isoforms by transfection into COS-1 cells, we have observed that Fc gamma RIIA induces the binding and phagocytosis of IgG-sensitized RBCs (EA) and that transfected COS-1 cells can serve as a model for examining the molecular structures involved in mediating a phagocytic signal. We now report that COS-1 cell transfectants expressing the isoforms Fc gamma RIIB1 and Fc gamma RIIB2 and a Fc gamma RIIA mutant without a cytoplasmic tail efficiently bind EA but do not mediate their phagocytosis. Furthermore, wild-type Fc gamma RIIA, but not Fc gamma RIIB1 or Fc gamma RBII2, was phosphorylated on tyrosine upon receptor activation. Tyrphostin 23, which alters tyrosine kinase activity, inhibited the phagocytosis of EA and reduced the phosphorylation of Fc gamma RIIA on tyrosine. Fc gamma RIIB1 and Fc gamma RIIB2 contain one copy of the cytoplasmic sequence YXXL/I implicated in signal transduction, whereas Fc gamma RIIA contains two copies. We therefore inserted YXXL/I sequences at different sites in Fc gamma RIIB2. Low levels of phagocytosis were observed in a Fc gamma RIIB2 mutant bearing the Fc gamma RIIA sequence YMTL and higher levels of phagocytosis were observed in a second Fc gamma RIIB2 mutant that contained both the upstream YMTL and an additional downstream tyrosine-containing motif. Activation of this mutant receptor also induced receptor tyrosine phosphorylation. Thus, these studies indicate that both the number and placement of YXXL sequences in the cytoplasmic domain of the Fc gamma RII receptor family affect both receptor tyrosine phosphorylation and phagocytic competence.
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Mitchell, MA, MM Huang, P. Chien, ZK Indik, XQ Pan et AD Schreiber. « Substitutions and deletions in the cytoplasmic domain of the phagocytic receptor Fc gamma RIIA : effect on receptor tyrosine phosphorylation and phagocytosis [published erratum appears in Blood 1994 Nov 1;84(9):3252] ». Blood 84, no 6 (15 septembre 1994) : 1753–59. http://dx.doi.org/10.1182/blood.v84.6.1753.1753.
Texte intégralRésumé :
Abstract Fc gamma RIIA in the absence of other Fc receptors or receptor subunits induces the ingestion of IgG-coated cells. The cytoplasmic domain of Fc gamma RIIA contains two Y-x-x-L sequences similar to those in other Ig gene family receptors plus an additional tyrosine residue not in a Y-x- x-L motif. Upon cross-linking, Fc gamma RIIA is phosphorylated on tyrosine and the cytoplasmic tyrosines, Y275 (Y1), Y282 (Y2), and Y298 (Y3), may be important for its phagocytic activity. Because COS-1 cells can serve as a model for examining molecular structures involved in phagocytosis, substitutions and deletions were introduced into the cytoplasmic domain of Fc gamma RIIA and examined in COS-1 cell transfectants for their effects on phagocytosis and tyrosine phosphorylation. Disruption of a single cytoplasmic Y-x-x-L motif by substitution of tyrosine Y2 or Y3 by phenylalanine or by removing the threonine and leucine residues within the motif inhibited phagocytosis 50% to 65%. Tyrosine phosphorylation of Fc gamma RIIA also was inhibited, although to a greater extent by the substitution of Y3 than of Y2. Replacement of the N-terminal first cytoplasmic domain tyrosine, Y1, which is not within a typical Y-x-x-L, by itself did not inhibit phagocytosis, but replacement of Y1 in mutants lacking Y2 or Y3 virtually eliminated phagocytic activity and receptor tyrosine phosphorylation. Thus, at least two cytoplasmic tyrosines, including at least one typical single Y-x-x-L motif, are required for phagocytosis by Fc gamma RIIA. The data suggest that there is a close but not a simple relationship between phosphorylation of the Fc gamma RIIA cytoplasmic tyrosines and Fc gamma RIIA-mediated phagocytosis. Y3 appears to be particularly important because its removal by truncation or replacement with phenylalanine inhibits both tyrosine phosphorylation and phagocytosis in parallel. Alterations in the 12 residue proline-containing sequence between the two Y-x-x-L motifs also reduced phagocytic activity and tyrosine phosphorylation. Thus, the specific structure of the Fc gamma RIIA cytoplasmic domain accounts for its ability to stimulate phagocytosis in the absence of other subunits.
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Mitchell, MA, MM Huang, P. Chien, ZK Indik, XQ Pan et AD Schreiber. « Substitutions and deletions in the cytoplasmic domain of the phagocytic receptor Fc gamma RIIA : effect on receptor tyrosine phosphorylation and phagocytosis [published erratum appears in Blood 1994 Nov 1;84(9):3252] ». Blood 84, no 6 (15 septembre 1994) : 1753–59. http://dx.doi.org/10.1182/blood.v84.6.1753.bloodjournal8461753.
Texte intégralRésumé :
Fc gamma RIIA in the absence of other Fc receptors or receptor subunits induces the ingestion of IgG-coated cells. The cytoplasmic domain of Fc gamma RIIA contains two Y-x-x-L sequences similar to those in other Ig gene family receptors plus an additional tyrosine residue not in a Y-x- x-L motif. Upon cross-linking, Fc gamma RIIA is phosphorylated on tyrosine and the cytoplasmic tyrosines, Y275 (Y1), Y282 (Y2), and Y298 (Y3), may be important for its phagocytic activity. Because COS-1 cells can serve as a model for examining molecular structures involved in phagocytosis, substitutions and deletions were introduced into the cytoplasmic domain of Fc gamma RIIA and examined in COS-1 cell transfectants for their effects on phagocytosis and tyrosine phosphorylation. Disruption of a single cytoplasmic Y-x-x-L motif by substitution of tyrosine Y2 or Y3 by phenylalanine or by removing the threonine and leucine residues within the motif inhibited phagocytosis 50% to 65%. Tyrosine phosphorylation of Fc gamma RIIA also was inhibited, although to a greater extent by the substitution of Y3 than of Y2. Replacement of the N-terminal first cytoplasmic domain tyrosine, Y1, which is not within a typical Y-x-x-L, by itself did not inhibit phagocytosis, but replacement of Y1 in mutants lacking Y2 or Y3 virtually eliminated phagocytic activity and receptor tyrosine phosphorylation. Thus, at least two cytoplasmic tyrosines, including at least one typical single Y-x-x-L motif, are required for phagocytosis by Fc gamma RIIA. The data suggest that there is a close but not a simple relationship between phosphorylation of the Fc gamma RIIA cytoplasmic tyrosines and Fc gamma RIIA-mediated phagocytosis. Y3 appears to be particularly important because its removal by truncation or replacement with phenylalanine inhibits both tyrosine phosphorylation and phagocytosis in parallel. Alterations in the 12 residue proline-containing sequence between the two Y-x-x-L motifs also reduced phagocytic activity and tyrosine phosphorylation. Thus, the specific structure of the Fc gamma RIIA cytoplasmic domain accounts for its ability to stimulate phagocytosis in the absence of other subunits.
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Van Den Herik-Oudijk, I. E., N. A. Westerdaal, N. V. Henriquez, P. J. Capel et J. G. Van De Winkel. « Functional analysis of human Fc gamma RII (CD32) isoforms expressed in B lymphocytes. » Journal of Immunology 152, no 2 (15 janvier 1994) : 574–85. http://dx.doi.org/10.4049/jimmunol.152.2.574.
Texte intégralRésumé :
Abstract The low affinity IgG receptor Fc gamma RII (CD32) represents the most widely distributed class of human Fc gamma R. To analyze the biologic functions of different Fc gamma RII isoforms, we stably transfected Fc gamma RIIb1, IIb1*, IIb2, IIa, and a IIa tail- mutant to the mouse IIA1.6 B lymphoma cell line. Of these, Fc gamma RIIb1* represents a receptor variant that is identical to IIb1 except for a single amino acid difference in the cytoplasmic tail (amino acid position 11) where a tyrosine (IIb1) is replaced by an aspartic acid (IIb1*). Evaluation of capping ability showed the Fc gamma RIIb1 molecules to cap effectively, which was even more apparent with IIb1*. None of the Fc gamma RIIa, IIa tail-, or IIb2 isoforms capped significantly. Internalization of Fc gamma R-antibody complexes proved very efficient for both the Fc gamma RIIa and IIb2 isoforms, whereas the IIb1 molecules internalized moderately compared with IIb1*, which internalized less efficiently. Notably, human IgG aggregates were internalized effectively by Fc gamma RIIa and moderately by IIb2. Neither Fc gamma RIIb1 nor IIb1* proved capable of internalizing such IgG aggregates. Cross-linking of the different Fc gamma R molecules showed Fc gamma RIIa capable of triggering increases in [Ca2+]i. Fc gamma R expressed on B cells were able to down-regulate [Ca2+]i on co-cross-linking with slgG. Notably, all three Fc gamma RIIb receptors proved active in this respect, in contrast to Fc gamma RIIa. The cell distribution of these Fc gamma RII isoforms was analyzed in a panel of human B cell lines to complement the IIA1.6 B cell model. Fc gamma RIIa was found expressed both at message and protein levels in all tested human B cell lines. In the pre-B cell lines evaluated, no Fc gamma RIIb molecules were detectable, whereas both Fc gamma RIIb1 and IIb2 molecules were found present in more mature B cell lines. These data support both a complex expression pattern of Fc gamma RII isoforms in B cell lines and functional differences between these B cell molecules.
Thèses sur le sujet "Fc��RIIA"
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Cooney, Damon Sean. « Proximal signaling events in Fc[gamma]RIIa-mediated phagocytosis / ». The Ohio State University, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486397841222421.
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Roll, Achim. « Nachweis des Fc[gamma]RIIa-Polymorphismus [Fc-gamma-RIIa-Polymorphismus] bei Patienten mit aggressiver Parodontitis (AP) und einer parodontal gesunden Kontrollgruppe mittels allelspezifischer PCR ». Giessen VVB Laufersweiler, 2009. http://d-nb.info/997994878/34.
Texte intégral
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Hammi, Ikram. « Le rôle du RFcγIIA dans la physiopathologie des leishmanioses cutanées ». Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASL132.
Texte intégralRésumé :
L'une des maladies tropicales négligées les plus répandues dans le monde, la leishmaniose cutanée, n'a pas de thérapie efficace malgré ses conséquences lourdes et malgré sa potentiel expansion dans les prochaines années. Au Maroc, les leishmaniose cutanée (LC) demeurent un problème de santé publique. 2813 cas ont en effet été notifiés en 2015 (Ministère de la Santé, Royaume du Maroc, Santé en Chiffres 2015, édition 2016). Ces LC sont principalement dues à deux espèces : Leishmania major responsable de la leishmaniose cutanée zoonotique, et Leishmania tropica responsable de la leishmaniose cutanée anthroponotique. Malgré la complexité et l'efficacité de la réponse immunitaire, le parasite a développé de nombreuses stratégies pour y échapper et prendre le contrôle de la cellule hôte en faveur de sa propre réplication. Ces stratégies d'évasion commencent dès les premières étapes de l'infection en détournant les récepteurs immunitaires afin d'éteindre la réponse immunitaire. Dans ce projet, nous avons étudié comment le parasite Leishmania pourrait utiliser le récepteur FcγIIA/ CD32a, ainsi que les voies de signalisation en aval, pour échapper à la réponse immunitaire de l'hôte. In vivo, l'expression de FRγIIA/CD32a accélère les signes d'inflammation, mais empêche la formation de lésions nécrotiques après infection avec Leishmania. In vitro, la présence de FRγIIA/CD32a n'affecte pas la sécrétion de cytokines pro-inflammatoires, bien que l'équilibre entre les complexes ITAMa et ITAMi soit perturbé, avec une activation accrue de SHP-1 et Lyn. Enfin, nous avons observé étonnamment que Leishmania tropica mais pas Leishmania major, induit un clivage intracytoplasmique du FRγIIA/CD32a. Ces résultats mettent en évidence le rôle que peut jouer le récepteur FRγIIA/CD32a dans la leishmaniose cutanée et suggèrent qu'il pourrait constituer une cible potentielle thérapeutiqueOne of the most widespread neglected tropical diseases in the world, cutaneous leishmaniasis, lacks an effective therapy despite its severe consequences and its potential expansion in the coming years. In Morocco, cutaneous leishmaniasis (CL) remains a public health issue. A total of 2813 cases have been reported by the Ministry of Health of Morocco. These CL cases are mainly caused by two species: Leishmania major, responsible for zoonotic cutaneous leishmaniasis, and Leishmania tropica, responsible for anthroponotic cutaneous leishmaniasis. Despite the complexity and effectiveness of the immune response, the parasite has developed many strategies to evade it and to take control of the host cell in favor of its replication. These evasion strategies start at earlier stages of the infection by hijacking immune receptors to silence the cellular response. Here we have investigated how Leishmania may use the Fc receptor FcγRIIA/CD32a and the signaling pathways downstream to evade the host immune response. In vivo, expression of FcγRIIA/CD32a accelerates the signs of inflammation but prevents the formation of necrotic lesions after Leishmania infection. In infected macrophages, the presence of FcvRIIA/CD32a does not affect the secretion of pro-inflammatory cytokines while the balance between ITAMa and ITAMi proteins is disturbed with an improved Fyn and Lyn activation. Unexpectedly, infection with Leishmania tropica but not Leishmania major triggered an intracytoplasmic processing of FcγRIIA/CD32a. Together, our observations underscore the significance of FcγRIIA/CD32a in cutaneous leishmaniasis and its possible use as a therapeutic target
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Beil, Elizabeth. « Identification of fcγRIIA STAT6 Interaction and the Subsequent Effects ». University of Toledo Health Science Campus / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=mco1332933291.
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Ertner, Julia Kathrin [Verfasser], et Christoph [Akademischer Betreuer] Garlichs. « Fc-gamma-RIIa- und Gen-Polymorphismen des C-reaktiven Proteins bei Patienten mit koronarer Restenose / Julia Kathrin Ertner. Betreuer : Christoph Garlichs ». Erlangen : Universitätsbibliothek der Universität Erlangen-Nürnberg, 2013. http://d-nb.info/103677497X/34.
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Roll, Achim [Verfasser]. « Nachweis des FcγRIIa-Polymorphismus [Fc-gamma-RIIa-Polymorphismus] bei Patienten mit aggressiver Parodontitis (AP) und einer parodontal gesunden Kontrollgruppe mittels allelspezifischer PCR / vorgelegt von Achim Roll ». Giessen : VVB Laufersweiler, 2009. http://d-nb.info/997994878/34.
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Iriemenam, Nnaemeka C. « Antibody responses and Fc gamma receptor IIa polymorphism in relation to Plasmodium falciparum malaria ». Doctoral thesis, Stockholms universitet, Wenner-Grens institut, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-27541.
Texte intégralRésumé :
Immunity to asexual blood-stage of Plasmodium falciparum malaria is believed to be associated with protective antibodies of certain immunoglobulin classes and subclasses. This thesis addressed the importance of antibodies in relation to malaria infection and their effective interactions with Fc gamma receptor IIa (FcyRIIa) polymorphisms. Our data indicate that the frequency of FcyRIIa-R/R131 genotype was statistically significantly higher in Sudanese patients with severe malaria, while the FcyRIIa-H/H131 genotype showed a significant association with mild malaria. The levels of IgG1 and IgG3 subclass antibodies were statistically higher in the mild malaria patients. The Fulani ethnic group in West Africa has been shown to be relatively resistant to malaria. We investigated the possible impact of FcyRIIa polymorphisms in the Fulani and non-Fulani in Mali and Sudan, and analysed their malaria-reactive IgG subclass profiles. The FcyRIIa-H/H131 genotype and H131-allele were found to be prevalent in the Fulani while R131-allele was prevalent in non-Fulani. The Fulani had higher serum levels of IgG1-3, with higher proportion of IgG2 than the non-Fulani. Most clinico-epidemiology studies have been in areas with holo- and hyper-malaria endemicity. We have analysed antibody responses to a panel of six blood-stage antigens in relation to clinical malaria outcome in mesoendemic Sudan. Our results revealed a linear association with anti-AMA-1 IgG1 antibodies and reduced risk of severe malaria while a non-linear relationship with IgG3 antibodies was observed for MSP-2, MSP-3 and GLURP. In the combined final model, the highest levels of IgG1 subclass antibodies to AMA-1, GLURP-R0, and the highest levels of IgG3 subclass antibodies reactive to 3D7 MSP-2 were independently associated with a reduced risk of clinical malaria. Taken together, these data suggest a possible association between FcyRIIa-R/H131 and anti-malarial antibody responses in the clinical outcome of malaria.
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Zhang, Christine. « Trafficking of FcγRIIA and FcγRIIB2 upon Endocytosis of Immune Complexes ». Thesis, 2012. http://hdl.handle.net/1807/35753.
Texte intégralRésumé :
Fcγ receptors (FcγR) which recognize the Fc fraction of IgG play key roles in the modulation of a range of cellular responses as part of the host defense against foreign microbes and antigens. An important function of FcγR is to mediate internalization of soluble IgG-containing immune complexes via endocytosis. The mechanisms of internalization and intracellular transport of FcγR after internalization are less clear. In this thesis, I investigated the trafficking behaviours of human FcγRIIA and FcγRIIB2 upon clustering with immune complexes. In Chapter 3, I demonstrate FcγRIIA, when engaged with multivalent heat aggregated IgG (agIgG), is delivered along with its ligand to lysosomal compartments for degradation, whereas FcγRIIB2 becomes dissociated from the ligand and routed separately into a recycling pathway. FcγRIIA sorting to lysosomes requires receptor multimerization, but does not require either Src family kinase (SFK) activity or receptor ubiquitylation. Upon co-engagement, these two receptors are sorted independently to distinct final fates after dissociating from their co-clustering ligand. In Chapter 4, I show that while the ubiquitin-conjugating system is required for FcγRIIA-mediated endocytosis, it is not required for FcγRIIB2 endocytosis. FcγRIIB2 internalizes immune complexes at a faster rate than FcγRIIA and accelerates the endocytosis of FcγRIIA upon receptor co-engagement. Taken together, these results reveal fundamental differences in the trafficking behaviour of FcγRIIA and FcγRIIB2 both during the initial induction of endocytosis as well as during subsequent intracellular sorting.
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Cendron, Angela. « The development of peptide-based inhibitors of the low affinity Fc receptor, Fc [gamma] RIIa ». Thesis, 2005. https://vuir.vu.edu.au/15580/.
Texte intégralRésumé :
FcyRIIa is an activatory receptor and contains an immunoreceptor tyrosine-based activation motif (ITAM) in its cytoplasmic domain, involved in the initiation of
signalling events. There is now strong evidence from transgenic mouse models and human genetic susceptibility studies that implicate FcyRIIa in a number of immune
diseases including, rheumatoid arthritis, systemic lupus erythematosus (SLE) and immune thrombocytopenia purpura (ITP). FcyRHa is therefore a promising target for the development of therapeutics to treat these diseases.
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Mangold, Melanie [Verfasser]. « Interaktion von C-reaktivem Protein mit FcγRI [Fc-gamma-RI] und FcγRIIa [Fc-gamma-RIIa] auf COS-7 Zellen : bindet CRP an Fc-Rezeptoren ? / vorgelegt von Melanie Mangold ». 2004. http://d-nb.info/995612684/34.
Texte intégralActes de conférences sur le sujet "Fc��RIIA"
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Dubaniewicz, Anna, Bartłomiej Rękawiecki, Anton Żawrocki, Hanna Majewska, Marek Piprek et Wojciech Biernat. « Fc?RIIA, Fc?RIII and Fc?RIIB expression in sarcoid granuloma and foreign body granuloma of the skin ». Dans ERS International Congress 2019 abstracts. European Respiratory Society, 2019. http://dx.doi.org/10.1183/13993003.congress-2019.pa1956.
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