Defective activation and survival of T cells lacking the Ets-1 transcription factor.

The Ets-1 proto-oncogene is a member of the Ets family of eukaryotic transcription factors. Members of this family play important roles in regulating gene expression in response to multiple developmental and mitogenic signals. Ets-1 is preferentially expressed at high levels in B and T cells of adult mice and is regulated during both thymocyte development and T-cell activation. To study the role of Ets-1 in T-cell development and function we have used the RAG-2-/- complementation system and murine embryonic stem (ES) cells containing homozygous deletions in the Ets-1 gene (Ets-1-/-). Ets-1-/(-)-RAG-2-/- chimaeric mice displayed markedly decreased numbers of mature thymocytes and peripheral T cells. Ets-1-/- T cells expressed normal levels of CD3 and T-cell antigen receptor (TCR)-alpha/beta. However, they displayed a severe proliferative defect in response to multiple activational signals and demonstrated increased rates of spontaneous apoptosis in vitro. These findings demonstrate that Ets-1 is required for the normal survival and activation of murine T cells.