Krüppel-like factor 4 regulates T cell function

Krüppel-like factor 4 (Klf4), a transcription factor mediating context-dependent activation or repression, plays a key role in maintaining pluripotency of stem cells and in regulating cell differentiation. However, the precise function of Klf4 in T cell development and differentiation is largely unknown. Here we showed that Klf4 was highly expressed in thymocyte subsets and mature T cells, and was rapidly down-regulated in mature T cells after activation. In T cell-specific Klf4 conditional knockout mice, we observed a modest reduction of thymocytes (27%). This was due partly to the loss of Klf4 repression of Cdkn1b expression in thymocytes resulting in decreased proliferation of DN thymocytes. Together, these findings identify Klf4 as a critical regulator in T cell development. Klf4fl/fl mice (Katz et al., 2002) were crossed with CD4-Cre mice (Lee et al., 2001) to generate Klf4fl/fl-CD4-Cre+ (Klf4 conditional knockout in T cells) and Klf4fl/fl-CD4-Cre- (control) mice. Mice used for experiments were between 8 and 10 weeks old. Total RNA was extracted from freshly isolated DP+SP4 thymocytes from 3 KO mice and 3 control mice. RNA samples were labeled and hybridized to Illumina Sentrix MouseRef-8 v2 bead arrays.