The Notch signaling pathway controls CD8+ T cell differentiation independently of the classical effector HES1.

During CD8+ T cell response, Notch signaling controls short-lived-effector-cell (SLEC) generation, but the exact mechanisms by which it does so remains unclear. The Notch signaling pathway can act as a key regulator of Akt signaling via direct transcriptional induction of Hes1, which will then repress the transcription of Pten, an inhibitor of Akt signaling. As both Notch and Akt signaling can promote effector CD8+ T cell differentiation, we asked whether Notch signaling influences SLEC differentiation via the HES1-PTEN axis. Here, we demonstrate that HES1 deficiency in murine CD8+ T cells did not impact SLEC differentiation. Moreover, we show that Pten transcriptional repression in effector CD8+ T cells is not mediated by Notch signaling although Akt activation requires Notch signaling. Therefore, HES1 is not an effector of Notch signaling during CD8+ T cell response.