Epac and phospholipase Cepsilon regulate Ca2+ release in the heart by activation of protein kinase Cepsilon and calcium-calmodulin kinase II.
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.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Cálcio
/
Sinalização do Cálcio
/
Fatores de Troca do Nucleotídeo Guanina
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Fosfoinositídeo Fosfolipase C
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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