PKC alpha regulates the hypertrophic growth of cardiomyocytes through extracellular signal-regulated kinase1/2 (ERK1/2).
Members of the protein kinase C (PKC) isozyme family are important signal transducers in virtually every mammalian cell type. Within the heart, PKC isozymes are thought to participate in a signaling network that programs developmental and pathological cardiomyocyte hypertrophic growth. To investigate the function of PKC signaling in regulating cardiomyocyte growth, adenoviral-mediated gene transfer of wild-type and dominant negative mutants of PKC alpha, beta II, delta, and epsilon (only wild-type zeta) was performed in cultured neonatal rat cardiomyocytes. Overexpression of wild-type PKC alpha, beta II, delta, and epsilon revealed distinct subcellular localizations upon activation suggesting unique functions of each isozyme in cardiomyocytes. Indeed, overexpression of wild-type PKC alpha, but not betaI I, delta, epsilon, or zeta induced hypertrophic growth of cardiomyocytes characterized by increased cell surface area, increased [(3)H]-leucine incorporation, and increased expression of the hypertrophic marker gene atrial natriuretic factor. In contrast, expression of dominant negative PKC alpha, beta II, delta, and epsilon revealed a necessary role for PKC alpha as a mediator of agonist-induced cardiomyocyte hypertrophy, whereas dominant negative PKC epsilon reduced cellular viability. A mechanism whereby PKC alpha might regulate hypertrophy was suggested by the observations that wild-type PKC alpha induced extracellular signal-regulated kinase1/2 (ERK1/2), that dominant negative PKC alpha inhibited PMA-induced ERK1/2 activation, and that dominant negative MEK1 (up-stream of ERK1/2) inhibited wild-type PKC alpha-induced hypertrophic growth. These results implicate PKC alpha as a necessary mediator of cardiomyocyte hypertrophic growth, in part, through a ERK1/2-dependent signaling pathway.
Braz
Julian C
JC
Department of Pediatrics, University of Cincinnati, Children's Hospital Medical Center, Cincinnati, OH 45229, USA.
Bueno
Orlando F
OF
De Windt
Leon J
LJ
Molkentin
Jeffery D
JD
D000818:Animals; D000831:Animals, Newborn; D009320:Atrial Natriuretic Factor / Q000187:drug effects / Q000378:metabolism; D002312:Cardiomyopathy, Hypertrophic / Q000201:enzymology* / Q000473:pathology / Q000503:physiopathology; D002451:Cell Compartmentation / Q000187:drug effects / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D006321:Heart / Q000187:drug effects / Q000254:growth & development* / Q000502:physiology; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000187:drug effects / Q000378:metabolism*; D048369:MAP Kinase Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism*; D009206:Myocardium / Q000166:cytology / Q000201:enzymology*; D011493:Protein Kinase C / Q000187:drug effects / Q000378:metabolism*; D051571:Protein Kinase C-alpha; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014404:Tubulin / Q000378:metabolism
D007527:Isoenzymes; D014404:Tubulin; D009320:Atrial Natriuretic Factor; D017346:Protein Serine-Threonine Kinases; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases