GA binding protein regulates interleukin 7 receptor alpha-chain gene expression in T cells.

The interleukin 7 receptor alpha-chain (IL-7Ralpha) is essential for T cell development in both humans and mice and for B cell development in mice. Whereas the transcription factor PU.1 regulates IL-7Ralpha expression in mouse pro-B cells via a GGAA motif, we demonstrate here that GA binding protein (GABP) bound to this site and was essential in the regulation of IL-7Ralpha expression in T cells, where PU.1 is not expressed. Moreover, IL-7Ralpha expression was diminished substantially in thymocytes but was normal on B220(+) fetal liver cells from mouse embryos with diminished expression of GABPalpha. Thus, GABP is essential for the regulation of IL-7Ralpha expression in T cells, and the differential regulation of IL-7Ralpha in distinct lymphoid lineages is achieved at least in part by differential recruitment of factors to the same GGAA motif.