An enhancer core element mediates stimulation of the rat beta-myosin heavy chain promoter by an alpha 1-adrenergic agonist and activated beta-protein kinase C in hypertrophy of cardiac myocytes.
In hypertrophy of cultured rat cardiac myocytes, alpha 1-adrenergic agonists activate protein kinase C (PKC) and up-regulate beta-myosin heavy chain (MHC). The 3300-base pair (bp) rat beta-MHC promoter is stimulated by both an alpha 1-agonist and a constitutively activated mutant of beta-PKC (Kariya, K., Karns, L. R., Simpson, P. C. (1991) J. Biol. Chem. 266, 10023-10026). Here, we report the convergence of alpha 1-adrenergic and beta-PKC signaling on the same element of the beta-MHC promoter. A 20-bp sequence in the beta-MHC promoter (-215/-196) was required for induction by both alpha 1-adrenergic stimulation and beta-PKC and conferred induction on a heterologous promoter. This sequence bound myocyte nuclear factor(s) through a 9-bp "enhancer core" (5'-TGTGGTATG-3'). A 3-bp mutation within the enhancer core which abolished factor binding also abolished inducibility of a 215-bp beta-MHC promoter. These results support the idea that beta-PKC is in the pathway for alpha 1-adrenergic regulation of beta-MHC transcription during cardiac myocyte hypertrophy. The enhancer core is the first PKC response element mapped by transfection of an activated PKC mutant, rather than by treatment with phorbol esters.
Kariya
K
K
Division of Cardiology, Veterans Affairs Medical Center, San Francisco, California 94121.
Karns
L R
LR
Simpson
P C
PC
D000818:Animals; D000831:Animals, Newborn; D001483:Base Sequence; D001665:Binding Sites; D006332:Cardiomegaly / Q000201:enzymology / Q000378:metabolism*; D002478:Cells, Cultured; D004742:Enhancer Elements, Genetic; D004789:Enzyme Activation; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009206:Myocardium / Q000201:enzymology / Q000378:metabolism*; D009218:Myosins / Q000096:biosynthesis / Q000235:genetics*; D009687:Nuclear Proteins / Q000378:metabolism; D009838:Oligodeoxyribonucleotides / Q000378:metabolism; D010656:Phenylephrine / Q000494:pharmacology*; D011401:Promoter Regions, Genetic / Q000187:drug effects*; D011493:Protein Kinase C / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D018340:Receptors, Adrenergic, alpha-1 / Q000187:drug effects / Q000502:physiology*; D012689:Sequence Homology, Nucleic Acid; D014162:Transfection
D007527:Isoenzymes; D009687:Nuclear Proteins; D009838:Oligodeoxyribonucleotides; D018340:Receptors, Adrenergic, alpha-1; D010656:Phenylephrine; D011493:Protein Kinase C; D009218:Myosins