Regulation of cardiac alpha-myosin heavy chain gene transcription by a contractile-responsive E-box binding protein.
The hemodynamic workload imposed on the heart modulates the expression of the cardiac-specific alpha-myosin heavy chain (MHC) gene. A hemodynamic responsive element (HME) has been mapped to an E box motif (CACGTG) located at position -47 of the promoter. The present studies showed that the HME is sufficient to confer contractile responsiveness to a heterologous promoter, the simian virus thymidine kinase gene, when expressed in cultured neonatal rat ventricular myocytes. Proximity of the HME to the TATA box of the alpha-MHC promoter appear necessary for high levels of basal transcription and for the four-fold induction in response to the contractile stimulus. An HME binding protein, approximately 43 kDa, was isolated from a neonatal rat ventricular myocyte cDNA library with sequence homology to the human upstream stimulatory factor-1 (hUSF1). Electrophoretic mobility shift assay showed that the in vitro translation product of the rat USF1 cDNA bound to the alpha-MHC HME motif and was recognized by an antibody to hUSF1. Overexpression of recombinant rat USF1 in spontaneously contracting cultured cardiomyocytes significantly increased activity of a cotransfected alpha-MHC promoter/luciferase reporter plasmid containing the HME motif plus core promoter elements (-40/+32), suggesting a role of rat USF1 in the contractile-mediated activation of the gene.
Xiao
Q
Q
Department of Medicine, North Shore University Hospital/NYU School of Medicine, Manhasset 11030, USA.
Ojamaa
K
K
D000595:Amino Acid Sequence; D000818:Animals; D000831:Animals, Newborn; D001483:Base Sequence; D002478:Cells, Cultured; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D009200:Myocardial Contraction / Q000235:genetics*; D009206:Myocardium / Q000166:cytology; D018995:Myosin Heavy Chains / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D051381:Rats; D011993:Recombinant Fusion Proteins; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics*; D051720:Upstream Stimulatory Factors
D004268:DNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C497181:USF1 protein, human; D051720:Upstream Stimulatory Factors; C497182:Usf1 protein, rat; D018995:Myosin Heavy Chains