title: A novel function of nuclear nonmuscle myosin regulatory light chain in promotion of xanthine oxidase transcription after myocardial ischemia/reperfusion.
abstract: Nuclear myosin regulates gene transcription and this novel function might be modulated through phosphorylation of the myosin regulatory light chain (p-MLC20). Nonmuscle MLC20 (nmMLC20) is also present in the nuclei of cardiomyocytes and a potential nmMLC20 binding sequence has been identified in the promoter of the xanthine oxidase (XO) gene. Thus, we investigated its function in the regulation of XO transcription after myocardial ischemia/reperfusion (IR). In a rat model of myocardial IR and a cardiomyocyte model of hypoxia/reoxygenation (HR) injury, the cardiac or cell injury, myosin light chain kinase (MLCK) content, XO expression and activity, XO-derived products, and level of nuclear p-nmMLC20 were detected. Coimmunoprecipitation (co-IP), chromatin immunoprecipitation, DNA pull-down, and luciferase reporter gene assays were used to decipher the molecular mechanisms through which nmMLC20 promotes XO expression. IR or HR treatment dramatically elevated nuclear p-nmMLC20 level, accompanied by increased XO expression, activity, and products (H2O2 and uric acid), as well as the IR or HR injury; these effects were ameliorated by inhibition of MLCK or knockdown of nmMLC20. Our findings from these experiments demonstrated that nuclear p-nmMLC20 binds to the consensus sequence GTCGCC in the XO gene promoter, interacts with RNA polymerase II and transcription factor IIB to form a transcription preinitiation complex, and hence activates XO gene transcription. These results suggest that nuclear p-nmMLC20 plays an important role in IR/HR injury by transcriptionally upregulating XO gene expression to increase oxidative stress in myocardium. Our findings demonstrate nuclear nmMLC20 as a potential new therapeutic target to combat cardiac IR injury.
authors.affiliation: Department of Pharmacology, School of Pharmaceutical Sciences, Central South University, Changsha 410078, China; Hunan Provincial Key Laboratory of Cardiovascular Research, School of Pharmaceutical Sciences, Central South University, Changsha 410078, China.
authors.forename: Yi-Shuai
authors.initials: YS
authors.lastname: Zhang
authors.affiliation: Department of Pharmacology, School of Pharmaceutical Sciences, Central South University, Changsha 410078, China; Hunan Provincial Key Laboratory of Cardiovascular Research, School of Pharmaceutical Sciences, Central South University, Changsha 410078, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
authors.affiliation: Department of Pharmacology, School of Pharmaceutical Sciences, Central South University, Changsha 410078, China; Hunan Provincial Key Laboratory of Cardiovascular Research, School of Pharmaceutical Sciences, Central South University, Changsha 410078, China.
authors.forename: Xiu-Ju
authors.initials: XJ
authors.lastname: Luo
authors.affiliation: Department of Pharmacology, School of Pharmaceutical Sciences, Central South University, Changsha 410078, China; Hunan Provincial Key Laboratory of Cardiovascular Research, School of Pharmaceutical Sciences, Central South University, Changsha 410078, China.
authors.forename: Jie-Jie
authors.initials: JJ
authors.lastname: Zhang
authors.affiliation: Department of Pharmacology, School of Pharmaceutical Sciences, Central South University, Changsha 410078, China; Hunan Provincial Key Laboratory of Cardiovascular Research, School of Pharmaceutical Sciences, Central South University, Changsha 410078, China.
authors.forename: Nian-Sheng
authors.initials: NS
authors.lastname: Li
authors.affiliation: Department of Cardiovascular Medicine, Xiangya Hospital, Central South University, Changsha 410008, China.
authors.forename: Qi-Lin
authors.initials: QL
authors.lastname: Ma
authors.affiliation: Department of Pharmacology, School of Pharmaceutical Sciences, Central South University, Changsha 410078, China; Hunan Provincial Key Laboratory of Cardiovascular Research, School of Pharmaceutical Sciences, Central South University, Changsha 410078, China.
authors.forename: Jun-Lin
authors.initials: JL
authors.lastname: Jiang
authors.affiliation: Department of Pharmacology, School of Pharmaceutical Sciences, Central South University, Changsha 410078, China; Hunan Provincial Key Laboratory of Cardiovascular Research, School of Pharmaceutical Sciences, Central South University, Changsha 410078, China.
authors.forename: Yuan-Jian
authors.initials: YJ
authors.lastname: Li
authors.affiliation: Department of Internal Medicine, The University of Texas Medical Branch, Galveston, TX 77555-1083, USA. Electronic address: quli@UTMB.EDU.
authors.forename: Qingjie
authors.initials: Q
authors.lastname: Li
authors.affiliation: Department of Pharmacology, School of Pharmaceutical Sciences, Central South University, Changsha 410078, China; Hunan Provincial Key Laboratory of Cardiovascular Research, School of Pharmaceutical Sciences, Central South University, Changsha 410078, China. Electronic address: Junpeng@csu.edu.cn.
authors.forename: Jun
authors.initials: J
authors.lastname: Peng
mesh_terms: D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism*; D049109:Cell Proliferation; D002478:Cells, Cultured; D047369:Chromatin Immunoprecipitation; D015971:Gene Expression Regulation, Enzymologic; D006861:Hydrogen Peroxide / Q000378:metabolism; D047468:Immunoprecipitation; D008297:Male; D017202:Myocardial Ischemia / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D015428:Myocardial Reperfusion Injury / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D018994:Myosin Light Chains / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014969:Xanthine Oxidase / Q000235:genetics* / Q000378:metabolism
chemical_list: D018994:Myosin Light Chains; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide; D014969:Xanthine Oxidase
keywords: Free radicals; Ischemia; Nonmuscle myosin regulatory light chain; Reperfusion; Transcription; Xanthine oxidase