A role for E2-2 at the DN3 stage of early thymopoiesis.

Roles for the E-proteins E2A and HEB during T lymphocyte development have been well established. Based on our previous observations of counter selection against T cells lacking E2-2, it seemed reasonable to assume that there would be a function also for E2-2 in thymocyte development. Aiming at assigning such a role for E2-2, we analyzed the expression of E2-2, E2A, HEB as well as Id mRNA during T cell development.

Transduction of naive CD4 T cells with kinase-deficient Lck-HIV-Tat fusion protein dampens T cell activation and provokes a switch to regulatory function.

We show here that T cell differentiation can be altered by exposing naive mouse CD4 T cells to altered T cell receptor signaling, achieved by transducing them with a fusion protein consisting of a modified Lck protein lacking the kinase domain and the HIV-Tat protein transduction domain. The Lck-HIV-Tat fusion protein is internalized into naive mouse T cells within 30 min after application to the medium. Activation of transduced cells in vitro resulted in strongly reduced intracellular calcium mobilization, alterations in cytokine profile, and sustained up-regulation of CD25.