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Titolo:
SYK, BUT NOT LYN, RECRUITMENT TO B-CELL ANTIGEN RECEPTOR AND ACTIVATION FOLLOWING STIMULATION OF CD45(-) B-CELLS
Autore:
PAO LI; CAMBIER JC;
Indirizzi:
NATL JEWISH HOSP,DEPT PEDIAT,DIV BASIC IMMUNOL,1400 JACKSON ST DENVERCO 80206 NATL JEWISH CTR IMMUNOL & RESP MED,DIV BASIC SCI,DEPT PEDIAT DENVER CO 80206 UNIV COLORADO,HLTH SCI CTR,DEPT IMMUNOL DENVER CO 80206
Titolo Testata:
The Journal of immunology
fascicolo: 6, volume: 158, anno: 1997,
pagine: 2663 - 2669
SICI:
0022-1767(1997)158:6<2663:SBNLRT>2.0.ZU;2-N
Fonte:
ISI
Lingua:
ENG
Soggetto:
PROTEIN-TYROSINE KINASE; PHOSPHORYLATED IG-ALPHA; SRC-FAMILY; PHOSPHOTYROSINE PHOSPHATASE; SIGNAL TRANSDUCTION; ENZYME-ACTIVITY; CROSS-LINKING; ASSOCIATION; LYMPHOCYTES; COMPONENTS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
51
Recensione:
Indirizzi per estratti:
Citazione:
L.I. Pao e J.C. Cambier, "SYK, BUT NOT LYN, RECRUITMENT TO B-CELL ANTIGEN RECEPTOR AND ACTIVATION FOLLOWING STIMULATION OF CD45(-) B-CELLS", The Journal of immunology, 158(6), 1997, pp. 2663-2669

Abstract

B cell Ag receptor (BCR) signaling occurs via tyrosine phosphorylation of CD79a and CD79b ITAMs, leading to recruitment and activation of Lyn and Syk tyrosine kinases and subsequent downstream events. CD45 expression is required for BCR triggering of certain of these downstream events, such as calcium mobilization and p21(ras) activation. However,the site in the BCR signaling cascade at which CD45 impinges is poorly defined. To address this question, we have studied CD45 function in the CD45-deficient (CD45(-)) and CD45-reconstituted (CD45(+)) J558L mum3 plasmacytoma. In both CD45(+) and CD45(-) cells, Ag stimulation led to CD79a and CD79b tyrosine phosphorylation as well as Syk tyrosine phosphorylation, recruitment to the receptors, and activation. In contrast to CD45(+) cells, Lyn exhibited high basal tyrosine phosphorylation in the CD45(-) cells and was not further phosphorylated upon Ag stimulation. Mapping studies indicated that the observed constitutive phosphorylation of Lyn reflects phosphorylation of its C-terminal tyrosine, Y508, at high stoichiometry. Constitutively Y508-phosphorylated Lynwas neither recruited to the BCR nor activated upon Ag stimulation. Moreover, CD79a-ITAM phosphopeptides failed to bind Lyn from the CD45(-) cells. Thus, Y508 phosphorylation of Lyn occurs in the absence of cellular CD45 expression and appears to render the kinase unable to associate with the phosphorylated receptor complex via its Src homology 2 domain and to participate in signal propagation. Surprisingly, in viewof previous findings implicating Src family kinases in ITAM phosphorylation, the data indicate that Ag-induced CD79a and CD79b tyrosine phosphorylation and Syk recruitment and activation can occur in the absence of CD45 expression and, hence, Src-family kinase activation.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 29/09/20 alle ore 22:35:26