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001-es BibID:	BIBFORM054348
035-os BibID:	PMID: 7843241
Első szerző:	Sármay Gabriella
Cím:	The alternative splicing of human FcγRII mRNA is regulated by activation of B cells with mIgM cross-linking, interleukin-4, or phorbolester / Gabriella Sármay, Zoltán Rozsnyay, Gábor Koncz, Alla Danilkovich, János Gergely
Dátum:	1995
ISSN:	0014-2980
Megjegyzések:	The human type two IgG binding receptors (Fc gamma RII) are encoded by three genes (Fc gamma RIIA, -B and C) resulting in at least six protein isoforms generated by alternative mRNA splicing. Surface expression of Fc gamma RTT has been shown to be modulated during B cell activation, although data characterizing the isoform(s) expressed are not available. The extracellular as well as the transmembrane domains of various Fc gamma RII are highly homologous. Only the intracellular domains vary between the different Fc gamma RII isoforms, suggesting differences in signal transduction. Using reverse transcriptase and polymerase chain reaction of mRNA obtained from resting tonsil B cells,we show that the majority of Fc gamma RII mRNA species to be of b2 type, although b1 type and a low level of Fc gamma RIIa type are also present. Culturing the cells for 18 h in the presence of 2.5 U/ml interleukin-4 or 10 mu g/ml affinity-purified anti-IgM F(ab')(2) fragments induced a switch in alternative splicing, resulting in a significant increase of Fc gamma RIIb1 mRNA expression, while the synthesis of Fc gamma RIIb2 mRNA was down-regulated. Stimulation of B cells with 100 ng/ml phorbol 12-myristate 13-acetate induced similar alteration, although only after 48-h treatment. The accumulation of Fc gamma RIIb1 and the reduction of both Fc gamma IIb2 and Fc gamma IIa mRNA in activated cells is accompanied by the enhanced expession of Fc gamma RII on the cell surface, representing most probably the Fc gamma RIIb1 isoform. Heat-aggregated IgG inhibited the anti-IgM-induced proliferation of resting but not that of activated B cells, suggesting that aggregation of Fc gamma RIIb2 constitutively expressed on resting B cells might be responsible for the prevention of inadequate activation of resting B cells.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban FC-GAMMA-RIIB B CELLS REGULATION
Megjelenés:	European Journal of Immunology. - 25 : 1 (1995), p. 262-268. -
További szerzők:	Rozsnyay Zoltán Koncz Gábor (1970-) (biológus, immunológus) Danilkovich, Alla Gergely János
Internet cím:	Szerző által megadott URL DOI Intézményi repozitóriumban (DEA) tárolt változat
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001-es BibID:	BIBFORM054331
035-os BibID:	PMID: 7797241
Első szerző:	Sármay Gabriella
Cím:	Interaction of signaling molecules with human FcγRIIb1 and the role of various FcγRIIb isoforms in B-cell regulation / Gabriella Sarmay, Zoltan Rozsnyay, Gabor Koncz, Janos Gergely
Dátum:	1995
ISSN:	0165-2478
Megjegyzések:	The low-affinity type-IIb IgG Fc-binding receptors (Fc gamma RIIb) are expressed on B cells. When cross-linked with mIgM Fc gamma RIIb are known to down-regulate B-cell activation by interrupting signal transduction upstream from G-protein-activated events. We have studied Fc gamma RII isoforms expressed on resting and activated B cells and the interaction of Fc gamma RIIb1 with molecules transducing the antigen receptor-mediated signals. Expression of Fc gamma RII isoforms was studied by reverse transcription and polymerase chain reaction. Resting B cells express both Fc gamma RIIb2 and Fc gamma RIIb1 isoforms. Activation with anti-IgM or IL-4 induces the splicing of Fc gamma RIIb1 mRNA, while the alternative splicing of Fc gamma RIIb2 mRNA is down-regulated, resulting in the surface expression of Fc gamma RIIb1. Functional differences were found between the two isoforms in-inhibiting B-cell activation, suggesting that Fc gamma RIIb2 might influence the threshold of signals necessary for activation of resting B cells, while Fc gamma RIIb1 may regulate in later phases of antibody response.To explore the mechanism by which Fc gamma RII may uncouple antigen receptor-mediated signal transduction, we have investigated the association of signaling molecules with Fc gamma RII. Beside the protein tyrosine kinase (PTK) fyn, protein kinase C (PKC) was found to be co-isolated with Fc gamma RIIb1, suggesting a tight connection between these kinases and Fc gamma RII. We suggest that PKC might be responsible for the activation-induced phosphorylation of Fc gamma RII on serine residues. Signaling molecules responsible for the activation and localization of further elements of the activation pathway were also found to associate with Fc gamma RII. Among these RasGAP and Shc, the adapter molecule connecting PTK-triggered events to the Ras activation-dependent pathway were characterized. We suggest that Fc gamma RII may compete with the B-cell antigen receptor for key molecules regulating Ras activity, inhibiting thereby Ras activation.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban HUMAN LYMPHOCYTES-B RECEPTOR PROTEIN PHOSPHORYLATION EXPRESSION ACTIVATION
Megjelenés:	Immunology Letters. - 44 : 2-3 (1995), p. 125-131. -
További szerzők:	Rozsnyay Zoltán Koncz Gábor (1970-) (biológus, immunológus) Gergely János
Internet cím:	Szerző által megadott URL DOI Intézményi repozitóriumban (DEA) tárolt változat
Borító:
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