A conserved GATA motif in a tissue-specific DNase I hypersensitive site of the cardiac alpha-myosin heavy chain gene.

Transgenic analysis has indicated that far upstream regulatory elements of the cardiac alpha-myosin heavy chain (MyHC) gene are required for appropriate transgene expression [Subramaniam, Gulick, Neumann, Knotts and Robbins (1993) J. Biol. Chem. 268, 4331-4336]. In an attempt to identify these as-yet-undefined regulatory elements, we mapped the DNase I hypersensitive sites (DHSs) in the 4 kb upstream region of the hamster cardiac alpha-MyHC gene. When using nuclei isolated from late-gestational and adult heart ventricles, a strong DHS was identified in the -1.9 kb region (alpha-1.9 kb site). It cannot be detected in kidney, liver or cardiofibroblast nuclei. Within this site, we found a conserved GATA-motif that interacts specifically with GATA-binding factors in nuclear extracts of cardiomyocytes at various developmental stages. These data provide further evidence to support the role of GATA factors in the regulation of cardiac alpha-MyHC gene expression.