Endothelin-1 induces phosphorylation of GATA-4 transcription factor in the HL-1 atrial-muscle cell line.

The transcription factor GATA-4 plays a central role in the regulation of cardiac-muscle gene transcription. The present study demonstrates that endothelin-1 (ET-1) induces GATA-4 activation and phosphorylation. The treatment of HL-1 adult mouse atrial-muscle cells with ET-1 (30 nM) caused a rapid increase in the DNA binding activity of GATA-4 within 3 min. The activation was associated with an upward mobility shift of the GATA-4 band on native PAGE in an electrophoretic- mobility-shift assay. The upward shift of the GATA-4 band also occurred on SDS/PAGE as monitored by immunoblotting. The in vitro treatment of nuclear extracts with lambda-protein phosphatase abolished the upward shift, indicating that GATA-4 was phosphorylated. ET-1 activated the p44/42 mitogen-activated protein kinase (MAPK) and the MAPK kinase (MEK) within 3 min, and PD98059 (a specific inhibitor of MEK) abolished the ET-1-induced GATA-4 phosphorylation. PMA also caused the rapid activation of MAPK and the phosphorylation of GATA-4. In contrast, the activation of MAPK by phenylephrine or H(2)O(2) was weak and did not lead to GATA-4 phosphorylation. Thus ET-1 induces a GATA-4 phosphorylation by activating a MEK-MAPK pathway.