title: Exogenous NAD(+) supplementation protects H9c2 cardiac myoblasts against hypoxia/reoxygenation injury via Sirt1-p53 pathway.
abstract: Nicotinamide adenine dinucleotide (NAD(+) ) not only transfers electrons in mitochondrial respiration, but also acts as an indispensable cosubstrate for Sirt1, the class III histone/nonhistone deacetylase. However, NAD(+) is depleted in myocardial ischemia/reperfusion (IR) injury. The objective of this study was to investigate the role of exogenous NAD(+) supplementation in hypoxia/reoxygenation (HR)-stressed H9c2 cardiac myoblasts. Firstly, the effects of distinct treating time points and doses of NAD(+) supplementation on the viability of HR-stressed H9c2 cells were detected. Secondly, intracellular NAD(+) levels in HR-stressed H9c2 cells at various extracellular NAD(+) concentrations were determined. Thirdly, the role of NAD(+) supplementation in HR-induced cell apoptosis and its relevance to Sirtuin 1-p53 pathway were investigated. Exogenous NAD(+) supplementation elevated intracellular NAD(+) level and reduced HR-induced cell death in both time- and concentration-dependent manners. It appeared that NAD(+) supplementation exerted the greatest protection when extracellular concentration ranged from 500 to 1000 μm and when NAD(+) was added immediately after reoxygenation began. NAD(+) replenishment restored Sirt1 activity, reduced the acetylation level of p53 (Lys373 & 382), and attenuated cell apoptosis in HR-stressed H9c2 cells, whereas inhibition of Sirt1 activity alleviated the effects of NAD(+) replenishment. These results indicated that exogenous NAD(+) supplementation attenuated HR-induced cell apoptosis, which was at least partly mediated by restoring Sirt1 activity and subsequently inhibiting p53 activity via deacetylating p53 at lysine 373 and 382.
authors: Department of Anesthesiology, the First Affiliated Hospital of Chongqing Medical University, Chongqing, 400016, China.
authors: Ling
authors: L
authors: Liu
authors: Ping
authors: P
authors: Wang
authors: Xinwei
authors: X
authors: Liu
authors: Dongwei
authors: D
authors: He
authors: Canxin
authors: C
authors: Liang
authors: Ying
authors: Y
authors: Yu
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D018929:Cell Culture Techniques; D015687:Cell Hypoxia / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D032386:Myoblasts, Cardiac / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D015428:Myocardial Reperfusion Injury / Q000378:metabolism; D009243:NAD / Q000378:metabolism / Q000494:pharmacology*; D010100:Oxygen / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects*; D056564:Sirtuin 1 / Q000378:metabolism*; D013997:Time Factors; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: D016159:Tumor Suppressor Protein p53; D009243:NAD; C488368:Sirt1 protein, rat; D056564:Sirtuin 1; D010100:Oxygen
keywords: Nicotinamide adenine dinucleotide; Sirt1; apoptosis; cardioprotection; hypoxia/reoxygenation; p53