title: Molecular identification for epigallocatechin-3-gallate-mediated antioxidant intervention on the H2O2-induced oxidative stress in H9c2 rat cardiomyoblasts.
abstract: BACKGROUND
  Epigallocatechin-3-gallate (EGCG) has been documented for its beneficial effects protecting oxidative stress to cardiac cells. Previously, we have shown the EGCG-mediated cardiac protection by attenuating reactive oxygen species and cytosolic Ca2+ in cardiac cells during oxidative stress and myocardial ischemia. Here, we aimed to seek a deeper elucidation of the molecular anti-oxidative capabilities of EGCG in an H2O2-induced oxidative stress model of myocardial ischemia injury using H9c2 rat cardiomyoblasts.
  
  
  RESULTS
  Proteomics analysis was used to determine the differential expression of proteins in H9c2 cells cultured in the conditions of control, 400 μM H2O2 exposure for 30 min with and/or without 10 to 20 μM EGCG pre-treatment. In this model, eight proteins associated with energy metabolism, mitochondrial electron transfer, redox regulation, signal transduction, and RNA binding were identified to take part in EGCG-ameliorating H2O2-induced injury in H9c2 cells. H2O2 exposure increased oxidative stress evidenced by increases in reactive oxygen species and cytosolic Ca2+ overload, increases in glycolytic protein, α-enolase, decreases in antioxidant protein, peroxiredoxin-4, as well as decreases in mitochondrial proteins, including aldehyde dehydrogenase-2, ornithine aminotransferase, and succinate dehydrogenase ubiquinone flavoprotein subunit. All of these effects were reversed by EGCG pre-treatment. In addition, EGCG attenuated the H2O2-induced increases of Type II inositol 3, 4-bisphosphate 4-phosphatase and relieved its subsequent inhibition of the downstream signalling for Akt and glycogen synthase kinase-3β (GSK-3β)/cyclin D1 in H9c2 cells. Pre-treatment with EGCG or GSK-3β inhibitor (SB 216763) significantly improved the H2O2-induced suppression on cell viability, phosphorylation of pAkt (S473) and pGSK-3β (S9), and level of cyclin D1 in cells.
  
  
  CONCLUSIONS
  Collectively, these findings suggest that EGCG blunts the H2O2-induced oxidative effect on the Akt activity through the modulation of PIP3 synthesis leading to the subsequent inactivation of GSK-3β mediated cardiac cell injury.
authors.forename: Wei-Cheng
authors.initials: WC
authors.lastname: Chen
authors.forename: Shih-Rong
authors.initials: SR
authors.lastname: Hsieh
authors.forename: Chun-Hwei
authors.initials: CH
authors.lastname: Chiu
authors.affiliation: Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu 30013, Taiwan. bdhsu@life.nthu.edu.tw.
authors.forename: Ban-Dar
authors.initials: BD
authors.lastname: Hsu
authors.forename: Ying-Ming
authors.initials: YM
authors.lastname: Liou
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage*; D017209:Apoptosis / Q000187:drug effects; D002392:Catechin / Q000008:administration & dosage / Q000031:analogs & derivatives*; D002470:Cell Survival / Q000187:drug effects; D038362:Glycogen Synthase Kinase 3 / Q000096:biosynthesis*; D006861:Hydrogen Peroxide / Q000633:toxicity; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D032446:Myoblasts / Q000166:cytology / Q000187:drug effects; D009206:Myocardium / Q000166:cytology; D018384:Oxidative Stress / Q000187:drug effects; D019869:Phosphatidylinositol 3-Kinases / Q000096:biosynthesis; D010766:Phosphorylation; D051381:Rats; D017382:Reactive Oxygen Species; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: D000975:Antioxidants; D017382:Reactive Oxygen Species; D002392:Catechin; D006861:Hydrogen Peroxide; C045651:epigallocatechin gallate; D019869:Phosphatidylinositol 3-Kinases; D038362:Glycogen Synthase Kinase 3