Shapiro, Michael J

Abstract T cell development depends on the coordinated interplay between receptor signaling and transcriptional activation/repression. We performed a genetic complementation screen, and identified a novel transcriptional repressor, NKAP. NKAP associates with HDAC3 and is part of a DNA-binding complex, as shown by chromatin immunoprecipitation. NKAP also associates with CIR, a part of the Notch corepressor complex. The expression of NKAP during T cell development inversely correlates with the expression of Notch target genes, implying that NKAP may modulate Notch-mediated transcription. To examine the function of NKAP in T cell development, Lck-cre NKAP conditional knockout mice were generated. Interestingly, loss of NKAP blocks development of alpha/beta but not gamma/delta T cells. In addition, lck-cre NKAP cKO DP T cells express 8- to 20-fold higher levels of Hes1, Deltex1 and CD25, providing in vivo evidence that NKAP functions as a transcriptional repressor, acting at least in part, by repression of the Notch pathway.