MYB IS Required for B-Selection During Thymopoises

Abstract

Abstractc-Myb is a transcription factor required during hematopoiesis and is crucial for multiple stages of thymopoiesis. Understanding c-Myb function during hematopoiesis has been greatly impeded due to the lack of a tractable genetic system. We have used the Cre/loxP approach to conditional mutagenesis to study c-Myb function during thymopoiesis. Thymocyte specific inactivation of the Myb locus demonstrated a block in DN3 to DN4 differentiation concomitant with impaired Vβ to DJβ recombination of the Tcrb locus suggesting that the inability to generate a TCRβ protein blocked DN3 differentiation. However, some DN3 thymocytes