title: Nonmuscle myosin light-chain kinase deficiency attenuates atherosclerosis in apolipoprotein E-deficient mice via reduced endothelial barrier dysfunction and monocyte migration.
abstract: BACKGROUND
  Endothelial dysfunction and monocyte migration are key events in the pathogenesis of atherosclerosis. Nonmuscle myosin light-chain kinase (nmMLCK), the predominant MLCK isoform in endothelial cells, has been shown to contribute to vascular inflammation by altering endothelial barrier function. However, its impact on atherogenesis remains unknown.
  
  
  RESULTS
  We investigated the role of nmMLCK in the development of atherosclerotic lesions in apolipoprotein E-deficient (apoE(-/-)) mice fed an atherogenic diet for 12 weeks. Histopathological examination demonstrated that nmMLCK deficiency (apoE(-/-)nmmlck(-/-)) reduced the size of aortic lesions by 53%, lipid contents by 44%, and macrophage deposition by 40%. Western blotting and reverse-transcription polymerase chain reaction revealed the expression of nmMLCK in aortic endothelial cells and peripheral blood monocytes. Measurements of transendothelial electric resistance indicated that nmMLCK deficiency attenuated endothelial barrier dysfunction caused by thrombin, oxidized low-density lipoprotein, and tumor necrosis factor α. In monocytes, nmMLCK deficiency reduced their migration in response to the chemokine monocyte chemoattractant protein-1. Further mechanistic studies showed that nmMLCK acted through both myosin light chain phosphorylation-coupled and -uncoupled pathways; the latter involved Rous sacracoma virus homolog genes-encoded tyrosine kinases (Src) signaling. Moreover, depletion of Src via gene silencing, site-specific mutagenesis, or pharmacological inhibition of Src greatly attenuated nmMLCK-dependent endothelial barrier dysfunction and monocyte migration.
  
  
  CONCLUSIONS
  Nonmuscle myosin light-chain kinase contributes to atherosclerosis by regulating endothelial barrier function and monocyte migration via mechanisms involving not only kinase-mediated MLC phosphorylation but also Src activation.
authors.affiliation: Department of Surgery, University of California Davis School of Medicine, 4625 2nd Ave, Room 3005, Sacramento, CA 95817, USA.
authors.forename: Chongxiu
authors.initials: C
authors.lastname: Sun
authors.forename: Mack H
authors.initials: MH
authors.lastname: Wu
authors.forename: Sarah Y
authors.initials: SY
authors.lastname: Yuan
mesh_terms: D000818:Animals; D001011:Aorta / Q000473:pathology; D001057:Apolipoproteins E / Q000172:deficiency* / Q000235:genetics / Q000502:physiology; D050197:Atherosclerosis / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D002465:Cell Movement / Q000502:physiology*; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D050356:Lipid Metabolism / Q000502:physiology; D008264:Macrophages / Q000473:pathology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009000:Monocytes / Q000473:pathology / Q000502:physiology*; D009219:Myosin-Light-Chain Kinase / Q000172:deficiency* / Q000235:genetics / Q000502:physiology; D010766:Phosphorylation; D015398:Signal Transduction / Q000502:physiology; D017539:Tunica Intima / Q000378:metabolism; D019061:src-Family Kinases / Q000502:physiology
chemical_list: D001057:Apolipoproteins E; D003094:Collagen; D019061:src-Family Kinases; D009219:Myosin-Light-Chain Kinase; C561451:non-muscle myosin light-chain kinase, mouse