title: cis-Acting sequences that mediate induction of beta-myosin heavy chain gene expression during left ventricular hypertrophy due to aortic constriction.
abstract: BACKGROUND
  Marked alterations in the expression of specific genes occur during the development of cardiac hypertrophy in vivo. Little is known, however, about the cis-acting elements that mediate these changes in response to clinically relevant hypertrophic stimuli, such as hemodynamic overload, in intact adult animals.
  
  
  RESULTS
  The left ventricular expression of a directly injected reporter gene driven by 3542 bp of rat beta-myosin heavy chain (beta-MHC) promoter was increased 3.0-fold by aortic constriction (P<.005), an increment similar to the 3.2-fold increase in the level of the endogenous beta-MHC mRNA in the same left ventricles. Subsequent analysis identified a 107-bp beta-MHC promoter sequence (-303/-197) sufficient to convert a heterologous neutral promoter to one that is activated by aortic constriction. These sequences contain two M-CAT elements, which have previously been demonstrated to mediate inducible expression during alpha1-adrenergic-stimulated hypertrophy in cultured neonatal cardiac myocytes, and a GATA element. Although simultaneous mutation of both M-CAT elements markedly decreased the basal transcriptional activity of an injected 333-bp beta-MHC promoter, it had no effect on aortic constriction-stimulated transcription (3.5-fold increase, P<.005 for both wild type and mutant). In contrast, mutation of the GATA motif markedly attenuated aortic constriction-stimulated transcription (1.6-fold, P=NS) without affecting the basal transcriptional activity. This GATA site can interact with in vitro translated GATA-4 and compete with an established GATA site for GATA-4 binding activity in nuclear extracts from aortic constricted hearts.
  
  
  CONCLUSIONS
  Basal and aortic constriction-stimulated transcription of the beta-MHC gene is mediated, at least in part, through different mechanisms. A GATA element within beta-MHC sequences -303/-197 plays a role in the transcriptional activation of this gene by aortic constriction.
authors.affiliation: Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
authors.forename: K
authors.initials: K
authors.lastname: Hasegawa
authors.forename: S J
authors.initials: SJ
authors.lastname: Lee
authors.forename: S M
authors.initials: SM
authors.lastname: Jobe
authors.forename: B E
authors.initials: BE
authors.lastname: Markham
authors.forename: R N
authors.initials: RN
authors.lastname: Kitsis
mesh_terms: D000818:Animals; D001018:Aortic Diseases / Q000150:complications*; D015152:Blotting, Northern; D003251:Constriction, Pathologic / Q000150:complications; D015342:DNA Probes; D004268:DNA-Binding Proteins / Q000235:genetics; D004586:Electrophoresis; D005260:Female; D050991:GATA4 Transcription Factor; D005786:Gene Expression Regulation; D006439:Hemodynamics; D017379:Hypertrophy, Left Ventricular / Q000209:etiology* / Q000235:genetics* / Q000503:physiopathology; D018995:Myosin Heavy Chains / Q000096:biosynthesis / Q000235:genetics*; D010957:Plasmids; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D014157:Transcription Factors / Q000235:genetics; D015533:Transcriptional Activation
chemical_list: D015342:DNA Probes; D004268:DNA-Binding Proteins; D050991:GATA4 Transcription Factor; D012333:RNA, Messenger; D014157:Transcription Factors; D018995:Myosin Heavy Chains