PU.1 regulates expression of the interleukin-7 receptor in lymphoid progenitors.

Development of the lymphoid system is dependent on the Ets family transcription factor PU.1. We demonstrate that PU.1(-/-) hematopoietic progenitors fail to express IL-7Ralpha transcripts. Promoter and chromatin crosslinking analyses suggest that PU.1 directly regulates transcription of the IL-7Ralpha gene. Retroviral transduction of IL-7Ralpha into PU.1(-/-) progenitors restores IL-7-dependent proliferation and induces, at low frequency, the generation of pro-B cells undergoing an apparently normal program of differentiation. Although the related factor Spi-B can substitute for PU.1 in early B cell development, it is not required. These results demonstrate that PU.1 functions to regulate early B cell development in part by controlling the expression of the IL-7Ralpha gene.