A ubiquitous factor (HF-1a) and a distinct muscle factor (HF-1b/MEF-2) form an E-box-independent pathway for cardiac muscle gene expression.

摘要: Recent studies have identified a conserved 28-bp element (HF-1) within the rat cardiac MLC-2 gene which confers muscle-specific and inducible expression during myocardial cell hypertrophy. Utilizing combination of independent experimental approaches, this study characterizes two nuclear factors bind to HF-1, ubiquitous factor (HF-1a), an A + T-rich binding (HF-1b) is preferentially expressed in differentiated skeletal muscle cells. The HF-1a site located core region element, immediately upstream from HF-1b site, homologous MEF-2 found number genes. By separate criteria (gel mobility shift, competition, mutagenesis studies), appear be indistinguishable thus are either identical or closely related factors. Transient assays luciferase reporter genes containing point mutations throughout HF-1 regulatory document importance both sites transient ventricular In native 250-bp promoter fragment, single E box had little effect on specificity, while significantly reduced activity, underscoring transcriptional activation gene. Thus, provides evidence that novel, (HF-1a) (HF-1b/MEF-2) can form E-box-independent pathway for