Phosphorylation of GATA-4 Is Involved in α1-Adrenergic Agonist-responsive Transcription of the Endothelin-1 Gene in Cardiac Myocytes

Abstract

The expression of endothelin-1 (ET-1) in cardiac myocytes is markedly induced during the development of heart failure in vivo and by stimulation with the ␣ 1 -adrenergic agonist phenylephrine in culture. Although recent studies have suggested a role for cardiac-specific zinc finger GATA factors in the transcriptional pathways that modulate cardiac hypertrophy, it is unknown whether these factors are also involved in cardiac ET-1 transcription and if so, how these factors are modulated during this process. Using transient transfection assays in primary cardiac myocytes from neonatal rats, we show here that the GATA element in the rat ET-1 promoter was required for phenylephrine-stimulated ET-1 transcription. Cardiac GATA-4 bound the ET-1 GATA element and activated the ET-1 promoter in a sequencespecific manner. Stimulation by phenylephrine caused serine phosphorylation of GATA-4 and increased its ability to bind the ET-1 GATA element. Inhibition of the extracellularly responsive kinase cascade with PD098059 blocked the phenylephrine-induced increase in the DNA binding ability and the phosphorylation of GATA-4. These findings demonstrate that serine phosphorylation of GATA-4 is involved in ␣ 1 -adrenergic agonist-responsive transcription of the ET-1 gene in cardiac myocytes and that extracellularly responsive kinase 1/2 activation plays a role upstream of GATA-4. Endothelin-1 (ET-1)1 was initially identified as a 21-amino acid vasoconstrictive peptide in porcine vascular endothelial cells (1). Later work showed that it acts not only as a vasoconstrictor but also as a potent growth-promoting peptide. For example, ET-1 can induce myocyte hypertrophy (2, 3) through coupling of ET receptors with G q protein. ET-1 signaling is also coupled with G i protein. Therefore, it is able to decrease intracellular cAMP levels (4). Although ET-1 is mainly produced by endothelial cells in the basal state, a number of cell types can synthesize ET-1 in response to various stimuli (5-8). ET-1 expression in cardiac myocytes is induced by myocardial stretch, angiotensin II, and norepinephrine (6 -8). Left ventricular levels of ET-1 increase markedly in close association with the deterioration of systolic function following myocardial infarction and pressure overload (9, 10). Immunohistochemical studies have demonstrated that ET-1 in the failing heart is localized in cardiac myocytes. ET receptor antagonists bosentan and BQ123 prevent the remodeling of the heart and have been shown to improve survival following myocardial infarction and pressure overload (9, 10). These findings demonstrate that up-regulated expression of ET-1 in cardiac myocytes plays a critical role in the development of heart failure in vivo. However, the molecular mechanisms leading to this up-regulation in the failing heart are unclear at present.The mechanisms regulating the transcription of the ET-1 gene have been studied in endothelial cells. The 204-bp sequences proximal to the transcription starting site is sufficient to drive high levels of expression in these...

Activation of GATA-4 by Serotonin in Pulmonary Artery Smooth Muscle Cells

“…GATA-4 can be activated by a signal transduction pathway involving calcineurin and NFAT3 (34). More recently, GATA-4 has shown also to be phosphorylated via the MEK/ERK pathway in response to ET-1 (27) or phenylephrine (28) in cardiac myocytes. Serine 105, the preferential ERK phosphorylation site, was identified to be phosphorylated in response to phenylephrine (25).…”

“…Because 5-HT-induced mitogenesis has been shown to be blocked by PD98059 (18) and GATA-4 can be phosphorylated via the MEK-ERK pathway in cardiac muscle cells (25,27,28), 5-HT may activate GATA-4 through ERK-dependent phosphorylation. Thus, the role of the MEK-ERK pathway in the 5-HTinduced GATA-4 activation was tested.…”

Oncogenic Ras upregulates NADPH oxidase 1 gene expression through MEK-ERK-dependent phosphorylation of GATA-6

“…These results indicate that GATA-6 is a component of protein complexes bound to the GATA sites of the Nox1 promoter. Phosphorylation of GATA-1, -2, -3 and -4 is known to modulate their DNA-binding and protein-protein interactions resulting in cell-and gene-specific transcriptions (Morimoto et al, 2000;Patient and McGhee, 2002;Yu et al, 2005). Likewise, GATA-6 contains consensus ERK phosphorylation sites (PXS/TP: PYS 120 P, PYS 192 P and PMT 369 P) (Suzuki et al, 1996).…”

FOG-2 Competes with GATA-4 for Transcriptional Coactivator p300 and Represses Hypertrophic Responses in Cardiac Myocytes

“…pCMVp300 was a gift from Dr. Richard Eckner (University of Zurich, Zurich, Switzerland). The reporter plasmid pET-CAT contains 204 bp of rat endothelin-1 (ET-1) promoter sequence fused to the bacterial CAT gene (23). In pmutGATA-ET-CAT, a GATA-4-binding site located at sequence Ϫ136 to Ϫ131 was mutated in the context of the 204-bp rat ET-1 promoter (23).…”

“…The reporter plasmid pET-CAT contains 204 bp of rat endothelin-1 (ET-1) promoter sequence fused to the bacterial CAT gene (23). In pmutGATA-ET-CAT, a GATA-4-binding site located at sequence Ϫ136 to Ϫ131 was mutated in the context of the 204-bp rat ET-1 promoter (23). pANFluc consists of the firefly luciferase (Luc) cDNA driven by a 131-bp rat ANF promoter sequence (12).…”