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Original Article |
j.wienands{at}uni-bielefeld.de
In latently infected B lymphocytes, the Epstein-Barr virus (EBV) suppresses signal transduction from the antigen receptor through expression of the integral latent membrane protein 2A (LMP2A). At the same time, LMP2A triggers B cell survival by a yet uncharacterized maintenance signal that is normally provided by the antigen receptor. The molecular mechanisms are unknown as LMP2A-regulated signaling cascades have not been described so far. Using a novel mouse model we have identified the intracellular adaptor protein Src homology 2 (SH2) domain–containing leukocyte protein (SLP)-65 as a critical downstream effector of LMP2A in vivo. Biochemical analysis of the underlying signaling pathways revealed that EBV infection causes constitutive tyrosine phosphorylation of one of the two SLP-65 isoforms and complex formation between SLP-65 and the protooncoprotein CrkL (CT10 regulator of kinase like). This leads to antigen receptor-independent phosphorylation of Cbl (Casitas B lineage lymphoma) and C3G. In contrast, phospholipase C-
2 (PLC-
2) activation is completely blocked. Our data show that in order to establish a latent EBV infection, LMP2A selectively activates or represses SLP-65–regulated signaling pathways.
Key Words: B lymphocytes Epstein-Barr virus antigen receptor SLP-65 signal transduction
2, phospholipase C-
2; PTK, protein tyrosine kinase; pTyr, phosphotyrosine; RAG, recombination activating gene; SLP, SH2 domain-containing leukocyte protein; SH2, Src homology 2 domain; WT, wild-type. © 2001 The Rockefeller University Press
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