A newly identified response element in the CD95 ligand promoter contributes to optimal inducibility in activated T lymphocytes.

Inducible expression of CD95 ligand on activated T lymphocytes contributes to both cytotoxic effector mechanisms and peripheral T cell homeostasis. To understand better the transcriptional events that regulate this expression, we have examined the CD95 ligand promoter to determine which regions are required for its induced activity following T cell stimulation. We report here the identification of a new response element within the promoter that is required for its optimal function in activated Jurkat T cells. This region is bound by proteins contained in nuclear extracts of activated, but not resting, T cells. Multimerization of this sequence independently drives transcription in response to T cell activation, while mutation of it substantially decreases inducible promoter activity. Finally, we provide evidence that T cell activation-induced transcription of the CD95 ligand gene is regulated coordinately by this response element together with two previously defined sites for nuclear factor of activated T cells (NFAT).