Involvement of NADPH oxidases and non-muscle myosin light chain in senescence of endothelial progenitor cells in hyperlipidemia

• Published in: Naunyn-Schmiedeberg's archives of pharmacology 2016-03, Vol.389 (3), p.289-302
• Main Authors: Li, Ting-Bo, Zhang, Jie-Jie, Liu, Bin, Liu, Wei-Qi, Wu, Yan, Xiong, Xiao-Ming, Luo, Xiu-Ju, Ma, Qi-Lin, Peng, Jun
• Format: Article
• Language: English
• Subjects: Animals; Azepines - pharmacology; Benzoxazoles - pharmacology; Biomedical and Life Sciences; Biomedicine; Cellular Senescence - physiology; Endothelial Progenitor Cells - metabolism; Hyperlipidemias - blood; Hyperlipidemias - metabolism; Lipids - blood; Male; Myosin Light Chains - metabolism; Myosin-Light-Chain Kinase - antagonists & inhibitors; Myosin-Light-Chain Kinase - metabolism; NADPH Oxidases - antagonists & inhibitors; NADPH Oxidases - genetics; NADPH Oxidases - metabolism; Naphthalenes - pharmacology; Neurosciences; Original Article; Pharmacology/Toxicology; Phosphorylation; Rats, Sprague-Dawley; Reactive Oxygen Species; RNA, Messenger - metabolism; RNA, Small Interfering - genetics; Triazoles - pharmacology
• ISSN: 0028-1298; 1432-1912
• DOI: 10.1007/s00210-015-1198-y

NADPH oxidase (NOX)-derived reactive oxygen species (ROS) is involved in endothelial dysfunction of hyperlipidemia, and non-muscle myosin regulatory light chain (nmMLC 20 ) is reported to have a transcriptional function in regulation of gene expression. The purposes of this study are to determine whether NOX-derived ROS can promote endothelial progenitor cell (EPC) senescence and whether nmMLC 20 can regulate NOX expression through a phosphorylation-dependent manner. The rats were subjected to 8 weeks of high-fat diet feeding to establish a hyperlipidemic model, which showed an increase in plasma lipids and the accelerated senescence and reduced number of circulating EPCs, accompanied by an increase in myosin light chain kinase (MLCK) and NOX activities, p-nmMLC 20 level, NOX (NOX2, NOX4) expression, and H 2 O 2 content. Next, EPCs isolated from normal rats were incubated with ox-LDL (100 μg/mL) for 24 h to establish a senescent model in vitro. Consistent with our in vivo findings, ox-LDL treatment increased the senescence of EPCs concomitant with an increase in MLCK and NOX activities, p-nmMLC 20 level (in total or nuclear proteins), NOX expression, and H 2 O 2 content; these phenomena were reversed by MLCK inhibitor. NOX inhibitor achieved similar results to that of MLCK inhibitor except that there is no effect on MLCK activity and p-nmMLC 20 level. Furthermore, knockdown of nmMLC 20 , NOX2, or NOX4 led to a down-regulation in NOX and a reduction in ox-LDL-induced EPC senescence. These results suggest that NOX-derived ROS promotes the senescence of circulating EPCs in hyperlipidemia and nmMLC 20 may play a transcriptional role in the upregulation of NOX through a phosphorylation-dependent manner.