Your browser doesn't support javascript.
loading
Epac and phospholipase Cepsilon regulate Ca2+ release in the heart by activation of protein kinase Cepsilon and calcium-calmodulin kinase II.
Oestreich, Emily A; Malik, Sundeep; Goonasekera, Sanjeewa A; Blaxall, Burns C; Kelley, Grant G; Dirksen, Robert T; Smrcka, Alan V.
Afiliação
  • Oestreich EA; Department of Pharmacology, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA.
J Biol Chem ; 284(3): 1514-22, 2009 Jan 16.
Article em En | MEDLINE | ID: mdl-18957419
Recently, we identified a novel signaling pathway involving Epac, Rap, and phospholipase C (PLC)epsilon that plays a critical role in maximal beta-adrenergic receptor (betaAR) stimulation of Ca2+-induced Ca2+ release (CICR) in cardiac myocytes. Here we demonstrate that PLCepsilon phosphatidylinositol 4,5-bisphosphate hydrolytic activity and PLCepsilon-stimulated Rap1 GEF activity are both required for PLCepsilon-mediated enhancement of sarcoplasmic reticulum Ca2+ release and that PLCepsilon significantly enhances Rap activation in response to betaAR stimulation in the heart. Downstream of PLCepsilon hydrolytic activity, pharmacological inhibition of PKC significantly inhibited both betaAR- and Epac-stimulated increases in CICR in PLCepsilon+/+ myocytes but had no effect in PLCepsilon-/- myocytes. betaAR and Epac activation caused membrane translocation of PKCepsilon in PLCepsilon+/+ but not PLCepsilon-/- myocytes and small interfering RNA-mediated PKCepsilon knockdown significantly inhibited both betaAR and Epac-mediated CICR enhancement. Further downstream, the Ca2+/calmodulin-dependent protein kinase II (CamKII) inhibitor, KN93, inhibited betaAR- and Epac-mediated CICR in PLCepsilon+/+ but not PLCepsilon-/- myocytes. Epac activation increased CamKII Thr286 phosphorylation and enhanced phosphorylation at CamKII phosphorylation sites on the ryanodine receptor (RyR2) (Ser2815) and phospholamban (Thr17) in a PKC-dependent manner. Perforated patch clamp experiments revealed that basal and betaAR-stimulated peak L-type current density are similar in PLCepsilon+/+ and PLCepsilon-/- myocytes suggesting that control of sarcoplasmic reticulum Ca2+ release, rather than Ca2+ influx through L-type Ca2+ channels, is the target of regulation of a novel signal transduction pathway involving sequential activation of Epac, PLCepsilon, PKCepsilon, and CamKII downstream of betaAR activation.
Assuntos

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Cálcio / Sinalização do Cálcio / Fatores de Troca do Nucleotídeo Guanina / Fosfoinositídeo Fosfolipase C / Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina / Miocárdio Tipo de estudo: Prognostic_studies Idioma: En Revista: J Biol Chem Ano de publicação: 2009 Tipo de documento: Article País de afiliação: Estados Unidos

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Cálcio / Sinalização do Cálcio / Fatores de Troca do Nucleotídeo Guanina / Fosfoinositídeo Fosfolipase C / Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina / Miocárdio Tipo de estudo: Prognostic_studies Idioma: En Revista: J Biol Chem Ano de publicação: 2009 Tipo de documento: Article País de afiliação: Estados Unidos