1. A novel function of nuclear nonmuscle myosin regulatory light chain in promotion of xanthine oxidase transcription after myocardial ischemia/reperfusion.
- Author
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Zhang, Yi-Shuai, Liu, Bin, Luo, Xiu-Ju, Zhang, Jie-Jie, Li, Nian-Sheng, Ma, Qi-Lin, Jiang, Jun-Lin, Li, Yuan-Jian, Li, Qingjie, and Peng, Jun
- Subjects
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NONMUSCLE myosin , *CORONARY disease , *MYOCARDIAL reperfusion , *XANTHINE oxidase , *MOLECULAR structure - Abstract
Nuclear myosin regulates gene transcription and this novel function might be modulated through phosphorylation of the myosin regulatory light chain (p-MLC 20 ). Nonmuscle MLC 20 (nmMLC 20 ) is also present in the nuclei of cardiomyocytes and a potential nmMLC 20 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-nmMLC 20 were detected. Coimmunoprecipitation (co-IP), chromatin immunoprecipitation, DNA pull-down, and luciferase reporter gene assays were used to decipher the molecular mechanisms through which nmMLC 20 promotes XO expression. IR or HR treatment dramatically elevated nuclear p-nmMLC 20 level, accompanied by increased XO expression, activity, and products (H 2 O 2 and uric acid), as well as the IR or HR injury; these effects were ameliorated by inhibition of MLCK or knockdown of nmMLC 20 . Our findings from these experiments demonstrated that nuclear p-nmMLC 20 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-nmMLC 20 plays an important role in IR/HR injury by transcriptionally upregulating XO gene expression to increase oxidative stress in myocardium. Our findings demonstrate nuclear nmMLC 20 as a potential new therapeutic target to combat cardiac IR injury. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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