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 | Yi-Shuai Zhang, Bin Liu, Xiu-Ju Luo, Jie-Jie Zhang, Nian-Sheng Li, Qi-Lin Ma, Jun-Lin Jiang, Yuan-Jian Li, Qingjie Li, Jun Peng |
Journal | Free radical biology & medicine
(Free Radic Biol Med)
Vol. 83
Pg. 115-28
(Jun 2015)
ISSN: 1873-4596 [Electronic] United States |
PMID | 25701432
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
|
Copyright | Copyright © 2015 Elsevier Inc. All rights reserved. |
Chemical References |
- Myosin Light Chains
- RNA, Messenger
- Reactive Oxygen Species
- Hydrogen Peroxide
- Xanthine Oxidase
|
Topics |
- Animals
- Apoptosis
- Blotting, Western
- Cell Nucleus
(genetics, metabolism)
- Cell Proliferation
- Cells, Cultured
- Chromatin Immunoprecipitation
- Gene Expression Regulation, Enzymologic
- Hydrogen Peroxide
(metabolism)
- Immunoprecipitation
- Male
- Myocardial Ischemia
(genetics, metabolism, pathology)
- Myocardial Reperfusion Injury
(genetics, metabolism, pathology)
- Myosin Light Chains
(genetics, metabolism)
- Oxidative Stress
- RNA, Messenger
(genetics)
- Rats
- Rats, Sprague-Dawley
- Reactive Oxygen Species
(metabolism)
- Real-Time Polymerase Chain Reaction
- Reverse Transcriptase Polymerase Chain Reaction
- Xanthine Oxidase
(genetics, metabolism)
|