Oxidized Low-Density Lipoprotein-Induced Cyclophilin A Secretion Requires ROCK-Dependent Diphosphorylation of Myosin Light Chain.
OBJECTIVE
Accumulation of cyclophilin A (CyPA) within atherosclerotic lesions is thought to be implicated in the progression of atherosclerosis. However, the source of CyPA within atherosclerotic lesions is still unknown. The aim of this study is to determine the role of oxidized low-density lipoproteins (ox-LDL) in vascular smooth muscle cell (VSMC)-derived CyPA secretion and the underlying mechanism.


RESULTS
Abundant CyPA and α-smooth muscle actin (α-SMA) expressed in atherosclerotic lesions was observed in apolipoprotein E-deficient mice. ox-LDL induced CyPA secretion from a primary culture of rat aortic smooth muscle cells in a dose- and time-dependent manner. Sulfosuccinimidyloleate, a CD36 inhibitor, prevented the ox-LDL-induced CyPA secretion. Pre-exposure to either the actin-depolymerizing agent cytochalasin D or the actin-polymerizing agent jasplakinolide inhibited CyPA secretion induced by ox-LDL. Gene silencing of vesicle-associated membrane protein 2 suppressed ox-LDL-induced CyPA secretion. ox-LDL caused the phosphorylation of myosin light chain (MLC). Inhibition of MLC by blebbistatin reversed the secretion of CyPA and the phosphorylation of MLC induced by ox-LDL. MLC kinase inhibitor ML-7 reduced the monophosphorylation of MLC but did not reduce CyPA secretion. Pretreatment with the rho-associated coiled-coil kinase (ROCK) inhibitor Y27632 blocked diphosphorylation of MLC and secretion of CyPA induced by ox-LDL.


CONCLUSIONS
ox-LDL-induced CyPA secretion requires vesicle transportation, actin remodeling and ROCK-dependent diphosphorylation of MLC. VSMC-derived CyPA induced by ox-LDL may be associated with increased CyPA expression in atherosclerotic lesions.
Department of Cardiology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, and Guangdong Province Key Laboratory of Arrhythmia and Electrophysiology, Guangzhou, China.
Zizhuo
Z
Su
Rongjie
R
Lin
Yuyang
Y
Chen
Xiaorong
X
Shu
Haifeng
H
Zhang
Shumin
S
Liang
Ruqiong
R
Nie
Jingfeng
J
Wang
Shuanglun
S
Xie
D000199:Actins / Q000378:metabolism; D000818:Animals; D001011:Aorta / Q000201:enzymology / Q000378:metabolism / Q000473:pathology; D001018:Aortic Diseases / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D001057:Apolipoproteins E / Q000172:deficiency / Q000235:genetics; D050197:Atherosclerosis / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D018955:CD36 Antigens / Q000378:metabolism; D002478:Cells, Cultured; D021984:Cyclophilin A / Q000378:metabolism*; D059305:Diet, High-Fat; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D008077:Lipoproteins, LDL / Q000494:pharmacology*; D008297:Male; D018345:Mice, Knockout; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D018994:Myosin Light Chains / Q000378:metabolism*; D010766:Phosphorylation; D034622:RNA Interference; D051381:Rats; D013997:Time Factors; D014162:Transfection; D054460:rho-Associated Kinases / Q000378:metabolism*
C558396:Acta2 protein, mouse; D000199:Actins; D001057:Apolipoproteins E; D018955:CD36 Antigens; C008132:Cd36 protein, rat; D008077:Lipoproteins, LDL; D018994:Myosin Light Chains; C099252:oxidized low density lipoprotein; D054460:rho-Associated Kinases; D021984:Cyclophilin A