title: ZIP kinase is responsible for the phosphorylation of myosin II and necessary for cell motility in mammalian fibroblasts.
abstract: Reorganization of actomyosin is an essential process for cell migration and myosin regulatory light chain (MLC20) phosphorylation plays a key role in this process. Here, we found that zipper-interacting protein (ZIP) kinase plays a predominant role in myosin II phosphorylation in mammalian fibroblasts. Using two phosphorylation site-specific antibodies, we demonstrated that a significant portion of the phosphorylated MLC20 is diphosphorylated and that the localization of mono- and diphosphorylated myosin is different from each other. The kinase responsible for the phosphorylation was ZIP kinase because (a) the kinase in the cell extracts phosphorylated Ser19 and Thr18 of MLC20 with similar potency; (b) immunodepletion of ZIP kinase from the cell extracts markedly diminished its myosin II kinase activity; and (c) disruption of ZIP kinase expression by RNA interference diminished myosin phosphorylation, and resulted in the defect of cell polarity and migration efficiency. These results suggest that ZIP kinase is critical for myosin phosphorylation and necessary for cell motile processes in mammalian fibroblasts.
authors.affiliation: Dept. of Physiology, University of Massachusetts Medical School, 55 Lake Ave. North, Worcester, MA 01655, USA.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Komatsu
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Ikebe
mesh_terms: D000818:Animals; D045163:Antibodies, Phospho-Specific / Q000378:metabolism; D051017:Apoptosis Regulatory Proteins; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002460:Cell Line; D002465:Cell Movement / Q000502:physiology*; D016764:Cell Polarity; D064550:Death-Associated Protein Kinases; D004791:Enzyme Inhibitors / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology / Q000502:physiology*; D016350:Leucine Zippers; D018994:Myosin Light Chains / Q000235:genetics / Q000378:metabolism; D024462:Myosin Type II / Q000378:metabolism*; D009219:Myosin-Light-Chain Kinase / Q000037:antagonists & inhibitors / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D013347:Subcellular Fractions / Q000737:chemistry / Q000378:metabolism
chemical_list: D045163:Antibodies, Phospho-Specific; D051017:Apoptosis Regulatory Proteins; D004791:Enzyme Inhibitors; D018994:Myosin Light Chains; D064550:Death-Associated Protein Kinases; D017346:Protein Serine-Threonine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D009219:Myosin-Light-Chain Kinase; D024462:Myosin Type II