Epigallocatechin-3-gallate-mediated cardioprotection by Akt/GSK-3β/caveolin signalling in H9c2 rat cardiomyoblasts

Abstract

BackgroundEpigallocatechin-3-gallate (EGCg) with its potent anti-oxidative capabilities is known for its beneficial effects ameliorating oxidative injury to cardiac cells. Although studies have provided convincing evidence to support the cardioprotective effects of EGCg, it remains unclear whether EGCg affect trans-membrane signalling in cardiac cells. Here, we have demonstrated the potential mechanism for cardioprotection of EGCg against H2O2-induced oxidative stress in H9c2 cardiomyoblasts.ResultsExposing H9c2 cells to H2O2 suppressed cell viability and altered the expression of adherens and gap junction proteins with increased levels of intracellular reactive oxygen species and cytosolic Ca2+. These detrimental effects were attenuated by pre-treating cells with EGCg for 30 min. EGCg also attenuated H2O2-mediated cell cycle arrest at the G1-S phase through the glycogen synthase kinase-3β (GSK-3β)/β-catenin/cyclin D1 signalling pathway. To determine how EGCg targets H9c2 cells, enhanced green fluorescence protein (EGFP) was ectopically expressed in these cells. EGFP-emission fluorescence spectroscopy revealed that EGCg induced dose-dependent fluorescence changes in EGFP expressing cells, suggesting that EGCg signalling events might trigger proximity changes of EGFP expressed in these cells.Proteomics studies showed that EGFP formed complexes with the 67 kD laminin receptor, caveolin-1 and -3, β-actin, myosin 9, vimentin in EGFP expressing cells. Using in vitro oxidative stress and in vivo myocardial ischemia models, we also demonstrated the involvement of caveolin in EGCg-mediated cardioprotection. In addition, EGCg-mediated caveolin-1 activation was found to be modulated by Akt/GSK-3β signalling in H2O2-induced H9c2 cell injury.ConclusionsOur data suggest that caveolin serves as a membrane raft that may help mediate cardioprotective EGCg transmembrane signalling.

H2O2 induces caveolin-1 degradation and impaired mitochondrial function in E11 podocytes

“…Crucially, the CAV-1 expression level was markedly affected by the addition of H 2 O 2 to the culture medium; the CAV-1 level decreased by nearly 50-70%. Similarly, previous studies demonstrated that the expression of CAV-1 is significantly decreased after H 2 O 2 treatment in cardiomyocytes and skeletal muscle cells (26,27). Several studies have suggested that the rapid degradation of CAV-1 protein could be caused by the ubiquitin-proteasome pathway, particularly after oxidative injury (28,29).…”

Pure Polyphenols Applications for Cardiac Health and Disease

“…Interestingly, proteomic studies demonstrated that EGCG has multiple cellular targets and binds to the 67kDa laminin receptor, caveolin-1 and -3, β-actin, myosin 9 and vimentin. Caveolin would serve as a membrane raft that may help mediate cardioprotective EGCG transmembrane signaling [61]. Moreover, in a high glucose model of arrhythmia in diabetic hearts, ECGC reverted the low levels of connexin 43 expression in a p38 MAPK-dependent manner in RNVC [62].…”

“…Hydrogen peroxide also alters the expression of adherens and gap junction proteins increasing intracellular ROS and Ca 2+ levels [61]. These effects were attenuated by pre-treatment with EGCG.…”

Catechin relieves hypoxia/reoxygenation‐induced myocardial cell apoptosis via down‐regulating lncRNA MIAT

“…40 Akt/Gsk-3β pathway has been shown to be involved in modulating oxidative stress and apoptosis, and the activation of Akt/Gsk-3β pathway preserved heart function and alleviated MI/R injury. 49 In this study, we clarified that the Akt/Gsk-3β pathway was activated by catechin and this activation was mediated by MIAT down-regulation in H/R-induced H9C2 cells. 47,48 Importantly, the activation of Akt/Gsk-3β pathway is involved in the cardioprotection function of EGCG.…”

“…47,48 Importantly, the activation of Akt/Gsk-3β pathway is involved in the cardioprotection function of EGCG. 49 In this study, we clarified that the Akt/Gsk-3β pathway was activated by catechin and this activation was mediated by MIAT down-regulation in H/R-induced H9C2 cells. To the best of our knowledge, no other studies figured out catechin improved mitochondrial function and reduced the apoptosis of H/R-induced H9C2 cells through regulating lncRNA MIAT/Akt/Gsk-3β pathway, which revealed the underlying mechanism of catechin in protecting against H/R-induced myocardial cell apoptosis.…”