Rho-kinase contributes to diphosphorylation of myosin II regulatory light chain in nonmuscle cells.
Phosphorylation of myosin II regulatory light chain (MRLC) is important for cell motility and cytokinesis in nonmuscle cells. Although the regulation of monophosphorylated MRLC at serine 19 throughout the cell cycle was examined in detail, MRLC diphosphorylation at both threonine 18 and serine 19 is still unclear. Here we found that Rho-kinase has an activity for MRLC diphosphorylation in nonmuscle cells using sequential column chromatographies. Transfection of Rho-kinase-EGFP induced the excess diphosphorylated MRLC and the bundling of the actin filaments. Conversely, the treatment of cells with a specific inhibitor of Rho-kinase, Y-27632, resulted in the decrease of endogenous diphosphorylated MRLC and actin stress fibers. Immunolocalization studies showed that both diphosphorylated MRLC and Rho-kinase accumulated and colocalized at the contractile ring and the midbody in dividing cells. Taken together, it is suggested that Rho-kinase contributes to MRLC diphosphorylation and reorganization of actin filaments in nonmuscle cells.
Department of Biological Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, 739-8526, Japan.
Kozue
K
Ueda
Maki
M
Murata-Hori
Masaaki
M
Tatsuka
Hiroshi
H
Hosoya
D008841:Actin Cytoskeleton / Q000378:metabolism / Q000648:ultrastructure; D000199:Actins / Q000378:metabolism; D000577:Amides / Q000494:pharmacology; D000595:Amino Acid Sequence; D002457:Cell Extracts; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006367:HeLa Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D009132:Muscles / Q000166:cytology; D018994:Myosin Light Chains / Q000187:drug effects / Q000378:metabolism*; D024462:Myosin Type II / Q000187:drug effects / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D054460:rho-Associated Kinases
D000199:Actins; D000577:Amides; D002457:Cell Extracts; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D018994:Myosin Light Chains; D011725:Pyridines; C108830:Y 27632; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D024462:Myosin Type II