JunD regulates lymphocyte proliferation and T helper cell cytokine expression

Abstract

Transgenic mice broadly expressing JunD (Ubi-junDm) appear phenotypically normal, but have strongly reduced numbers of peripheral lymphocytes. JunD overexpression in lymphocytes does not protect from numerous apoptotic insults; however, transgenic T cells proliferate poorly and exhibit impaired activation due to reduced levels of IL-4, CD25 and CD69. Consistently, in the absence of JunD (junD-/-) T cells hyperproliferate following mitogen induction. Moreover, transgenic T helper (Th) 2 cells have decreased IL-4 and IL-10 expression, whereas junD-/- Th2 cells secrete higher amounts of both Th2 cytokines. Th1-polarized junD-/- CD4+ T cells display enhanced IFN-γ cytokine production associated with upregulated T-bet expression and downregulated expression of suppressor of cytokine signaling-1. These novel findings demonstrate a regulatory role of JunD in T lymphocyte proliferation and Th cell differentiation.