Distinct requirements for activation-induced cell surface expression of preformed Fas/ XXXX ligand and cytolytic granule markers in T cells.

@entity3220 @entity1197 @entity4621 @entity12 @entity460 @entity5775
Fas ( @entity1197 / @entity1197 is a potent inducer of apoptosis and one of the major killing effector mechanisms of cytotoxic T cells. Thus, @entity12 activity has to be tightly regulated, involving various transcriptional and post-transcriptional processes. For example, preformed @entity12 is stored in secretory lysosomes of activated T cells, and rapidly released by degranulation upon reactivation. In this study, we analyzed the minimal requirements for activation-induced degranulation of @entity12 . T cell receptor activation can be mimicked by @entity460 ionophore and @entity4621 . Unexpectedly, we found that stimulation with @entity4621 alone is sufficient to trigger @entity12 release, whereas @entity460 ionophore is neither sufficient nor necessary. The relevance of this process was confirmed in primary CD4(+) and CD8(+) T cells and NK cells. Although the activation of protein kinase(s) was absolutely required for @entity12 degranulation, protein kinase C or A were not involved. Previous reports have shown that preformed @entity12 co-localizes with other markers of cytolytic granules. We found, however, that the activation-induced degranulation of @entity12 has distinct requirements and involves different mechanisms than those of the granule markers @entity5775 and @entity3220 / @entity3220 . We conclude that activation-induced degranulation of @entity12 in cytotoxic lymphocytes is differently regulated than other classical cytotoxic granule proteins.
