Regulation of T-cell death-associated gene 51 (TDAG51) expression in human T-cells.

T-cell death-associated gene 51 (TDAG51) has been described to regulate T-cell receptor/CD3-dependent induction of CD95/Fas and subsequent activation-induced cell death (AICD) in a murine T-cell hybridoma. Using well-defined pharmacological inhibitors, we investigated the regulation of TDAG51 expression in human T-cells and the correlation with cell death. TDAG51 was induced in resting T-cells, lymphoid cell lines and AICD-susceptible as well as AICD-resistant T-cell clones, and induction was inhibited by MAP-kinase inhibitors and PKC inhibitor Gö6983. No correlation between the effects of inhibitors on TDAG51 expression and cell death was observed. The constitutive TDAG51 expression in five pancreatic carcinoma cell lines was reduced by MAP-kinase inhibitors but not by Gö6983. Furthermore, the inducible overexpression of TDAG51 in TetOn Jurkat cells did not modulate cellular proliferation, phorbolester/ionomycin-induced growth arrest, or the expression of various cell surface molecules. Our results indicate that the expression of TDAG51 in human T-cells does not correlate with AICD.