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001-es BibID:	BIBFORM054321
035-os BibID:	PMID: 10382761
Első szerző:	Koncz Gábor (biológus, immunológus)
Cím:	Fcγ receptor-mediated inhibition of human B cell activation : the role of SHP-2 phosphatase / Gábor Koncz, Israel Pecht, János Gergely, Gabriella Sármay
Dátum:	1999
ISSN:	0014-2980
Megjegyzések:	Co-clustering of the type II receptors binding the Fc part of IgG (Fc gamma RIIb) and B cell receptors results in the translocation of cytosolic, negative regulatory molecules to the phosphorylated immunoreceptor tyrosine-based inhibitory motif (P-ITIM) of the FcyRIIb. SH2 domain-containing protein tyrosine phosphatases (SHP-1 and SHP-2), and the polyphosphoinositol 5'-phosphatase (SHIP) have been reported earlier to bind to murine Fc gamma RIIb P-ITIM. However, neither the functional substrates of these enzymes, nor the mechanism of the inhibition are fully resolved. We show here that the human Fc gamma RIIb binds SHP-2 when co-clustered with the B cell receptors, whereas its synthetic P-ITIM peptide bindes SHP-2 and SHIP in lysates of the Burkitt's lymphoma cell line BL41. The P-ITIM peptide binding enhances SHP-2 activity resulting in dephosphorylation and release of P-ITIM-bound SHIP and She. Moreover, P-ITIM-bound SHP-2 dephosphorylates synthetic peptides corresponding to the sites of tyrosine phosphorylation on SHIP and She, indicating that these proteins are its potential substrates. Thus SHP-2-induced dephosphorylation may modulate the intracellular localization and/or activity of SHIP and She, thereby inhibiting further activation pathways which they mediate.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban SHP-2 Fc gamma RIIb human B cell
Megjelenés:	European Journal of Immunology. - 29 : 6 (1999), p. 1980-1989. -
További szerzők:	Pecht, Israel Gergely János Sármay Gabriella
Internet cím:	Intézményi repozitóriumban (DEA) tárolt változat
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001-es BibID:	BIBFORM054306
Első szerző:	Medgyesi Dávid
Cím:	Functional mapping of the FcγRII binding site on human IgG1 by synthetic peptides / Dávid Medgyesi, Katalin Uray, Krisztina Sallai, Ferenc Hudecz, Gábor Koncz, Jakub Abramson, Israel Pecht, Gabriella Sármay, János Gergely
Dátum:	2004
ISSN:	0014-2980
Megjegyzések:	Receptors specific for the Fc part of IgG (FcgammaR) are expressed by several cell types and play diverse roles in immune responses. Impaired function of the activating and inhibitory FcgammaR may result in autoimmunity. Thus, the modulation of IgG-FcgammaR interaction can be a target for the development of treatments for some autoimmune and inflammatory diseases. This study addresses the localization and functional characterization of linear sequences in human IgG1 which bind to FcgammaRII. Peptides with overlapping sequences derived from the CH2 domain of human IgG1 between P(234) and S(298) were synthesized and used in binding and functional experiments. Binding of the peptides to FcgammaR was assayed in vitro and ex vivo, and peptides found to interact were functionally tested. The shortest effective peptide was T(216)-p(271) which bound to soluble recombinant Fc-gammaRIIb with K(d)=6x10(6) M(-1). The biotinylated peptides R(255)-p(271) and T(256)-p(271) complexed by avidin exhibited functional activity; they induced FcgammaRIIb-mediated inhibition of the BCR-triggered Ca(2+) response of human Burkitt lymphoma cells, and inflammatory cytokine production (TNF-alpha and IL-6) by the human monocyte cell line MonoMac. In conclusion, our results suggest that the selected peptides functionally represent the Fc-gammaRII-binding part of IgG1.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban IgG Fc gamma Re fc peptide binding site
Megjelenés:	European Journal of Immunology. - 34 : 4 (2004), p. 1127-1135. -
További szerzők:	Uray Katalin Sallai Krisztina Hudecz Ferenc Koncz Gábor (1970-) (biológus, immunológus) Abramson, Jakub Pecht, Israel Sármay Gabriella Gergely János
Pályázati támogatás:	AKP 2000-40 3,3 MTA
Internet cím:	Szerző által megadott URL DOI Intézményi repozitóriumban (DEA) tárolt változat
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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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