EXPRESSION IN HEMATOPOIETIC-CELLS OF GATA-1 TRANSCRIPTS FROM THE ALTERNATIVE TESTIS PROMOTER DURING DEVELOPMENT AND CELL-DIFFERENTIATION

GATA-1 is a transcription factor expressed both in the hematopoietic s ystem and in the Sertoli cells of the testis, and is essential for cor rect erythropoiesis. Hematopoietic and Sertoli cells transcribe GATA-1 from two different promoters: the proximal (erythroid) is active in h ematopoietic cells; the distal (testis) is active in Sertoli cells. We investigated by RT-PCR the possibility that GATA-1 might be transcrib ed from the testis promoter also in hematopoietic cells. Testis promot er-derived transcripts are present at low levels in vivo at all stages of hematopoietic development. Purified multipotent progenitors, fract ionated into populations expressing low or high levels of GATA-1, do n ot contain any ''testis'' transcripts. However, when grown in vitro, t hey rapidly express GATA-1 from the testis promoter in the presence of Erythropoietin (Epo) but not in that of other growth factors. This re sult reflects an Epo-dependent differentiation event, rather than a di rect effect of Epo. Indeed, immortalized progenitor cell lines which r espond to both Epo and SCF, continue to express testis-derived transcr ipts when switched from Epo to SCF. (C) 1997 Academic Press.