title: Dual regulation of tumor necrosis factor-α on myosin light chain phosphorylation in vascular smooth muscle.
abstract: We previously demonstrated that inhibitor κB kinase 2 (IKK2) is a myosin light chain kinase (MLCK). In the present study, we assess whether the prototypical activator of IKK2 tumor necrosis factor-α (TNF-α) regulates the MLCK activity of IKK2 and thus MLC phosphorylation in vascular smooth muscle cells (VSMCs). Kinase activity assay revealed that TNF-α downregulated the MLCK activity of IKK2 in human VSMCs (HVSMCs). However, Western blot analysis did not demonstrate a significant effect of TNF-α on MLC phosphorylation in HVSMCs, and myograph analysis did not reveal a significant effect of TNF-α on the contraction of the aorta from Sprague-Dawley rats and C57Bl/6j mice, suggesting a dual regulation of MLC phosphorylation by TNF-α. Confirming this notion, TNF-α significantly increased MLC phosphorylation in IKK2(-/-) but not wild-type cells. Furthermore, our results show that TNF-α increased GTP-bound RhoA and MLC phosphatase subunit MYPT1 phosphorylation and markedly reduced MLC phosphorylation in the presence of Rho-kinase inhibitor Y-27632, suggesting that downregulation of MLCK activity of IKK2 by TNF-α is antagonized by simultaneous RhoA/Rho-kinase activation. These results indicate that TNF-α dually regulates MLC phosphorylation through both IKK2 and RhoA/Rho-kinase pathways.
authors.affiliation: Department of Cardiology, East Hospital, Tongji University School of Medicine, Shanghai, People's Republic of China; Davis Heart and Lung Research Institute, Ohio State University Medical Center, Columbus, Ohio; and.
authors.forename: Minjie
authors.initials: M
authors.lastname: Chen
authors.affiliation: Department of Cardiology, East Hospital, Tongji University School of Medicine, Shanghai, People's Republic of China;
authors.forename: Lan
authors.initials: L
authors.lastname: Ma
authors.affiliation: Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi.
authors.forename: John E
authors.initials: JE
authors.lastname: Hall
authors.affiliation: Department of Cardiology, East Hospital, Tongji University School of Medicine, Shanghai, People's Republic of China;
authors.forename: Xuebo
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Cardiology, East Hospital, Tongji University School of Medicine, Shanghai, People's Republic of China; Davis Heart and Lung Research Institute, Ohio State University Medical Center, Columbus, Ohio; and yingzhekang@hotmail.com.
authors.forename: Zhekang
authors.initials: Z
authors.lastname: Ying
mesh_terms: D000577:Amides / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D002460:Cell Line; D002478:Cells, Cultured; D006801:Humans; D051550:I-kappa B Kinase / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009119:Muscle Contraction; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D018994:Myosin Light Chains / Q000378:metabolism*; D010766:Phosphorylation; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
chemical_list: D000577:Amides; D018994:Myosin Light Chains; D011725:Pyridines; D014409:Tumor Necrosis Factor-alpha; C108830:Y 27632; D054460:rho-Associated Kinases; D051550:I-kappa B Kinase; D020742:rhoA GTP-Binding Protein
keywords: IKK2; MLC phosphorylation; blood pressure; inflammation; vasoconstriction