Notch2 integrates signaling by the transcription factors RBP-J and CREB1 to promote T cell cytotoxicity

How T cell cytotoxic activity is induced remains incompletely defined. Yasutomo and colleagues now show that Notch2 signals, in direct cooperation with the transcription factor CREB1, promote granzyme B expression. The acquisition of cytotoxic effector function by CD8 + T cells is crucial for the control of intracellular infection and tumor invasion. However, it remains unclear which signaling pathways are required for the differentiation of CD8 + cytotoxic T lymphocytes. We show here that Notch2-deficient T cells had impaired differentiation into cytotoxic T lymphocytes. In addition, dendritic cells with lower expression of the Notch ligand Delta-like 1 induced the differentiation of cytotoxic T lymphocytes less efficiently. We found that the intracellular domain of Notch2 interacted with a phosphorylated form of the transcription factor CREB1, and together these proteins bound the transcriptional coactivator p300 to form a complex on the promoter of the gene encoding granzyme B. Our results suggest that the highly regulated, dynamic control of T cell cytotoxicity depends on the integration of Notch2 and CREB1 signals.