Growth hormone directly stimulates GATA2 expression

Objective: GATA2 is a key transcription factor involved in the differentiation and determination of thyrotrophs and gonadotrophs in pituitary and hematopoietic development. However, studies on the upstream ligands of the GATA2 signal transduction pathway have been limited. To identify upstream ligands, we examined growth hormone (GH) as a plausible stimulator. Design: We evaluated GH-induced GATA2 expression in murine TtT/GF thyrotrophic pituitary tumor cells and its direct impact on the GHR/JAK/STAT5 pathway using a combination of a reporter assay, real-time quantitative polymerase chain reaction, and western blotting. Results: GATA2 expression increased with activated STAT5B in a dose -dependent manner and was inhibited by a STAT5 specific inhibitor. Moreover, we found functional STAT5B binding site consensus sequences at -359 bp in the GATA2 promoter region. Conclusion: These findings suggest that GH directly stimulates GATA2 via the GHR/JAK/STAT pathway and participates in various developmental phenomena mediated by GATA2.