[The TRAF family protein-mediated B cell proliferation signal and the mechanism of LMP1-induced B cell transformation]

Abstract

We have demonstrated that CD40 signallings induce Bcl-xL, Cdk4 and 6 expression and suppress p27kip-1 expression to block apoptosis and induce B cell proliferation. We have also identified putative signal transducers of CD40, designated TRAF5 and TRAF6, in addition to TRAF1, 2 and 3 demonstrated by others. The EBV transforming protein LMP1 binds to TRAF proteins through the cytoplasmic region required for B cell transformation. Thus, LMP1 appears to be a constitutively activated CD40 receptor on the basis of an ability to aggregate in the plasma membrane and its association with TRAF proteins. However, regulation of the Bcl-xL, Cdk4 and 6 and p27kip-1 expression by LMP1 and the molecular mechanism of LMP1-mediated B cell transformation remain to be elucidated.