title: Thymosin beta 4 protects cardiomyocytes from oxidative stress by targeting anti-oxidative enzymes and anti-apoptotic genes.
abstract: BACKGROUND
  Thymosin beta-4 (Tβ4) is a ubiquitous protein with many properties relating to cell proliferation and differentiation that promotes wound healing and modulates inflammatory mediators. The mechanism by which Tβ4 modulates cardiac protection under oxidative stress is not known. The purpose of this study is to dissect the cardioprotective mechanism of Tβ4 on H(2)O(2) induced cardiac damage.
  
  
  METHODS
  Rat neonatal cardiomyocytes with or without Tβ4 pretreatment were exposed to H(2)O(2) and expression of antioxidant, apoptotic, and anti-inflammatory genes was evaluated by quantitative real-time PCR and western blotting. ROS levels were estimated by DCF-DA using fluorescent microscopy and fluorimetry. Selected antioxidant, anti-inflammatory and antiapoptotic genes were silenced by siRNA transfections in neonatal cardiomyocytes and effect of Tβ4 on H(2)O(2)-induced cardiac damage was evaluated.
  
  
  RESULTS
  Pre-treatment of Tβ4 resulted in reduction of the intracellular ROS levels induced by H(2)O(2) in cardiomyocytes. Tβ4 pretreatment also resulted in an increase in the expression of antiapoptotic proteins and reduction of Bax/BCl(2) ratio in the cardiomyocytes. Pretreatment with Tβ4 resulted in stimulating the expression of antioxidant enzymes copper/zinc SOD and catalase in cardiomyocytes at both transcription and translation levels. Tβ4 treatment resulted in the increased expression of anti-apoptotic and anti-inflammatory genes. Silencing of Cu/Zn SOD and catalase gene resulted in apoptotic cell death in the cardiomyocytes which was prevented by treatment with Tβ4.
  
  
  CONCLUSIONS
  This is the first report that demonstrates the effect of Tβ4 on cardiomyocytes and its capability to selectively upregulate anti-oxidative enzymes, anti-inflammatory genes, and antiapoptotic enzymes in the neonatal cardiomyocytes thus preventing cell death thereby protecting the myocardium. Tβ4 treatment resulted in decreased oxidative stress and inflammation in the myocardium under oxidative stress.
authors.affiliation: Division of Molecular Cardiology, Department of Medicine, College of Medicine, Texas A & M Health Science Center; Scott & White; Central Texas Veterans Health Care System, Temple, Texas, United States of America.
authors.forename: Chuanyu
authors.initials: C
authors.lastname: Wei
authors.forename: Sandeep
authors.initials: S
authors.lastname: Kumar
authors.forename: Il-Kwon
authors.initials: IK
authors.lastname: Kim
authors.forename: Sudhiranjan
authors.initials: S
authors.lastname: Gupta
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000975:Antioxidants / Q000378:metabolism*; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics*; D002470:Cell Survival / Q000187:drug effects; D019610:Cytoprotection / Q000187:drug effects*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D020287:In Situ Nick-End Labeling; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008856:Microscopy, Fluorescence; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects* / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D013947:Thymosin / Q000494:pharmacology*; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics; D000099201:Thymosin beta(4)
chemical_list: D000975:Antioxidants; D006861:Hydrogen Peroxide; D016328:NF-kappa B; D009569:Nitric Oxide; D013482:Superoxide Dismutase; D013481:Superoxides; D013947:Thymosin; D000099201:Thymosin beta(4)