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001-es BibID:BIBFORM054308
035-os BibID:PMID: 12008033
Első szerző:Koncz Gábor (biológus, immunológus)
Cím:BCR mediated signal transduction in immature and mature B cells / Gábor Koncz, Csaba Bodor, Dorottya Kövesdi, Róbert Gáti, Gabriella Sármay
Dátum:2002
ISSN:0165-2478
Megjegyzések:Ligation of B cell receptors (BCR) on immature B cells may induce apoptosis, while in mature B cells it stimulates cell activation and growth. The signaling pathway regulating the differential functional response, death or survival of the B cell is not fully characterized. We have tested the intracellular signaling requirement of these processes using B cells isolated from the spleen of irradiated auto-reconstituted (transitional immature B cells) and untreated mice (mature B cells), respectively. We compared the BCR induced intracellular [Ca(2+)] transient, protein tyrosine phosphorylation and ERK phosphorylation, furthermore, the activation of Elk-1 and CREB transcription factors. The BCR induced rise of intracellular [Ca(2+)] did not significantly differ in the two populations, only a slight difference in the late phase of the response was observed. Immature B cells responded with a maximum tyrosine phosphorylation to a five times lower dose of anti-IgM compared to the mature population. Most importantly, we have found a significant difference in the tyrosine phosphorylation of the Gab family adaptor proteins, Gab1/2. In contrast to mature B cells, crosslinking of BCR on immature B cells did not induce tyrosine phosphorylation of Gab2, thus the Gab2-organized signal amplification complex could not be produced. Furthermore, we detected a significant difference in the kinetics of BCR induced ERK, Elk-1 and CREB phosphorylation. In immature B cells, ERK was transiently phosphorylated, ceasing after 120 min, while in mature cells, ERK phosphorylation was sustained. Elk-1 and CREB activation was also transient in immature B cells, followed the kinetics of ERK phosphorylation. The lack of sustained Erk1/2 activation suppresses the transcription factors necessary for the proliferation signal. Since ERK is regulated by the phosphorylated Gab1/2, these data demonstrate that BCR triggered phosphorylation and signal amplification of Gab1/2 is a critical step in a life or death decision of B cells.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Immunology Letters. - 82 : 1-2 (2002), p. 41-49. -
További szerzők:Bodor Csaba Kövesdi Dorottya Gáti Róbert Sármay Gabriella
Pályázati támogatás:Bolyai Janos Kutatasi Osztondij
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2.

001-es BibID:BIBFORM054309
035-os BibID:PMID: 11897497
Első szerző:Kövesdi Dorottya
Cím:Developmental differences in B cell receptor-induced signal transduction / Dorottya Kövesdi, Gábor Koncz, Roland Iványi-Nagy, Yael Caspi, Masamichi Ishiai, Tomohiro Kurosaki, János Gergely, Joseph Haimovich, Gabriella Sármay
Dátum:2002
ISSN:0898-6568
Megjegyzések:We have compared early signaling events at various stages of B cell differentiation using established mouse cell lines. Clustering of pre-B cell antigen receptor (BCR) or BCR induced the tyrosine phosphorylation of various proteins in all cells, although the phosphorylation pattern differed. In spite of the pre-BCR-induced tyrosine phosphorylation, we could not detect an intracellular Ca(2+) signal in pre-B cells. However. coclustering of the pre-BCR with CD19 did induce Ca(2+) mobilization. In contrast to the immature and mature B cells, where the B cell linker protein (BLNK) went through inducible tyrosine phosphorylation upon BCR clustering, we observed a constitutive tyrosine phosphorylation of BLNK in pre-B cell lines. Both BLNK and phospholipase C (PLC)gamma were raft associated in unstimulated pre-B cells, and this could not be enhanced by pre-BCR engagement, suggesting a ligand-independent PLC-gamma-mediated signaling. Further results indicate that the cell lines representing the immature stage are more sensitive to BCR-, CD19- and type II receptors binding the Fe part of IgG (FcgammaRIIb)mediated signals than mature B cells.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
B cell
development
receptors
signaling
tyrosine phosphorylation
Megjelenés:Cellular Signalling. - 14 : 6 (2002), p. 563-572. -
További szerzők:Koncz Gábor (1970-) (biológus, immunológus) Iványi-Nagy Roland Caspi, Yael Ishiai, Masamichi Kurosaki, Tomohiro Gergely János Haimovich, Joseph Sármay Gabriella
Pályázati támogatás:Bolyai János Kutatási Ösztöndíj
Egyéb
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3.

001-es BibID:BIBFORM054299
035-os BibID:PMID: 18950707
Első szerző:Maus Máté
Cím:Grb2 associated binder 2 couples B-cell receptor to cell survival / Máté Maus, Dávid Medgyesi, Dorottya Kövesdi, Dorottya Csuka, Gábor Koncz, Gabriella Sármay
Dátum:2009
ISSN:0898-6568
Megjegyzések:B-cell fate during maturation and the germinal center reaction is regulated through the strength and the duration of the B-cell receptor signal. Signaling pathways discriminating between apoptosis and survival in B cells are keys in understanding adaptive immunity. Gab2 is a member of the Gab/Dos adaptor protein family. It has been shown in several model systems that Gab/Dos family members may regulate both the anti-apoptotic PI3-K/Akt and the mitogenic Ras/MAPK pathways, still their role in B-cells have not been investigated in detail. Here we studied the role of Gab2 in B-cell receptor mediated signaling. We have shown that BCR crosslinking induces the marked phosphorylation of Gab2 through both Lyn and Syk kinases. Subsequently Gab2 recruits p85 regulatory subunit of PI3-K. and SHP-2. Our results revealed that Ig-alpha/Ig-beta, signal transducing unit of the B-cell receptor, may function as scaffold recruiting Gab2 to the signalosome. Overexpression of Gab2 in A20 cells demonstrated that Gab2 is a regulator of the PI3-K/Akt but not that of the Ras/MAPK pathway in B cells. Accordingly to the elevated Akt phosphorylation, overexpression of wild-type Gab2 in A20 cells suppressed Fas-mediated apoptosis, and enhanced BCR-mediated rescue from Fas-induced cell death. Although PH-domain has only a stabilizing effect on membrane recruitment of Gab2, it is indispensable in mediating its anti-apoptotic effect. (c) 2008 Elsevier Inc. All rights reserved.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
B-cell
Signaling
Gab2 adaptor/scaffolding protein
Phosphorylation
PH domain
Survival
Megjelenés:Cellular Signalling. - 21 : 2 (2009), p. 220-227. -
További szerzők:Medgyesi Dávid Kövesdi Dorottya Csuka Dorottya Koncz Gábor (1970-) (biológus, immunológus) Sármay Gabriella
Pályázati támogatás:OTKA-K60760
OTKA
GVOP-2004-05-3.1.1/3.00183
GVOP
NKFP-1-A/040/2004
Egyéb
CellKom REr/06
Egyéb
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4.

001-es BibID:BIBFORM054318
Első szerző:Sármay Gabriella
Cím:Signaling pathways leading to apoptosis or survival in immature and mature B cells / G. Sármay, G. Koncz, Cs. Bodor, D. Kövesdi, R. Gáti, J. Gergely
Dátum:2002
ISSN:0077-8923
Megjegyzések:In the absence of phosphorylated Gab2, immature B cells are unable to maintain a prolonged signal transduction, which is necessary for the transcriptional regulation and activation of the cells. Thus, the lack of Gab2 phosphorylation may drive immature B cells to apoptosis.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
apoptosis
B cell
development
signaling
Megjelenés:Annals of the New York Academy of Sciences. - 973 (2002), p. 181-185. -
További szerzők:Koncz Gábor (1970-) (biológus, immunológus) Bodor Csaba Kövesdi Dorottya Gáti Róbert Gergely János
Pályázati támogatás:Bolyai Janos Kutatasi Osztondij
Egyéb
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