Transcription factor GATA-4 regulates cardiac muscle-specific expression of the alpha-myosin heavy-chain gene.

Abstract

The alpha-myosin heavy-chain (alpha-MHC) gene is the major structural protein in the adult rodent myocardium. Its expression is restricted to the heart by a complex interplay of trans-acting factors and their cis-acting sites. However, to date, the factors that have been shown to regulate expression of this gene have also been found in skeletal muscle cells. Recently, transcription factor GATA-4, which has a tissue distribution limited to the heart and endodermally derived tissues, was identified. We recently found two putative GATA-binding sites within the proximal enhancer of the alpha-MHC gene, suggesting that GATA-4 might regulate its expression. In this study, we establish that GATA-4 interacts with the alpha-MHC GATA sites to stimulate cardiac muscle-specific expression. Mutation of the GATA-4-binding sites either individually or together decreased activity by 50 and 88% in the adult myocardium, respectively. GATA-4-dependent enhancement of activity from a heterologous promoter was mediated through the alpha-MHC GATA sites. Coinjection of an alpha-MHC promoter construct with a GATA-4 expression vector permitted ectopic expression in skeletal muscle but not in fibroblasts. Thus, the lack of alpha-MHC expression in skeletal muscle correlates with a lack of GATA-4. GATA-4 DNA binding activity was significantly up-regulated in triiodothyronine- or retinoic acid-treated cardiomyocytes. Putative GATA-4-binding sites are also found in the regulatory regions of other cardiac muscle-expressed structural genes. This indicates a mechanism whereby triiodothyronine and retinoic acid can exert coordinate control of the cardiac phenotype through a trans-acting regulatory factor.

Angiotensin II type 1a receptor gene expression in the heart: AP-1 and GATA-4 participate in the response to pressure overload

“…This site was selected for study because it has been shown to be important for the cardiac muscle-specific expression of the ␣-MHC, troponin C slow/cardiac , brain natriuretic peptide (BNP), and atrial natriuretic factor (ANF) genes (9,10,29,30). The latter is expressed in adult ventricular cardiac myocytes only in response to hypertrophic stimuli (22).…”

“…Site-specific mutations were introduced into the AT 1a R promoter cloned into pBluescript SK(Ϫ) by rolling circle PCR as previously described (10,16). Mutations in the AP-1 site were introduced using AT1R-APmut and AT-AP-PCR as primers.…”

“…Nuclear extracts were prepared from adult rat tissues, and gel shift assays were performed as described earlier (10). Extracts were prepared from hearts of sham or coarcted animals that were harvested at 48 hr postcoarctation.…”

Myocardial Lipidomics. Developments in myocardial nuclear lipidomics

“…GATA4 is a transcription factor that is found specifically in cardiac cell nuclei. Comparisons of the amounts of GATA4 (cardiac cell marker) to GATA2 (non-cardiac cell marker) can be used to show the relative enrichment of cardiac and non-cardiac cell nuclei (8,17,18).…”

“…GATA4 is a transcription factor that is found specifically in cardiac cell nuclei. Comparisons of the amounts of GATA4 (cardiac cell marker) to GATA2 (non-cardiac cell marker) can be used to show the relative enrichment of cardiac and non-cardiac cell nuclei (8,17,18).The use of marker enzyme analyses for the purity of the nuclear preparations is particularly important in comparisons of nuclear phospholipids in hearts subjected to intense stress such as ischemia, ischemia/reperfusion and infarction. Under these conditions, the subcellular integrity could vary considerably, resulting in disparate isolation and purity of subcellular fractions.…”