Signaling from Rho to the Actin Cytoskeleton Through Protein Kinases ROCK and LIM-kinase

• Published in: Science (American Association for the Advancement of Science) 1999-08, Vol.285 (5429), p.895-898
• Main Authors: Maekawa, Midori, Ishizaki, Toshimasa, Boku, Shuken, Watanabe, Naoki, Fujita, Akiko, Iwamatsu, Akihiro, Obinata, Takashi, Ohashi, Kazumasa, Mizuno, Kensaku, Narumiya, Shuh
• Format: Article
• Language: English
• Subjects: Actin; Actin Cytoskeleton - metabolism; Actin Depolymerizing Factors; Actins; Actins - metabolism; Amides - pharmacology; Animals; Antibodies; Biological and medical sciences; Cell structures and functions; Cellular biology; COS Cells; Cytoskeleton; Cytoskeleton, cytoplasm. Intracellular movements; DNA-Binding Proteins - metabolism; Enzyme Activation; Fundamental and applied biological sciences. Psychology; Gels; GTP Phosphohydrolases - metabolism; GTP-Binding Proteins - metabolism; HeLa Cells; Humans; Intracellular Signaling Peptides and Proteins; Lim Kinases; Lysophospholipids - pharmacology; Membrane Proteins - metabolism; Microfilament Proteins - metabolism; Microfilaments; Molecular and cellular biology; Morphogenesis; Neurites; Phosphorylation; Physiological aspects; Protein Kinases - metabolism; Protein-Serine-Threonine Kinases - metabolism; Proteins; Pyridines - pharmacology; rho-Associated Kinases; rhoB GTP-Binding Protein; Signal Transduction; Stimuli; Stress fibers; Tumor Cells, Cultured
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.285.5429.895

The actin cytoskeleton undergoes extensive remodeling during cell morphogenesis and motility. The small guanosine triphosphatase Rho regulates such remodeling, but the underlying mechanisms of this regulation remain unclear. Cofilin exhibits actin-depolymerizing activity that is inhibited as a result of its phosphorylation by LIM-kinase. Cofilin was phosphorylated in N1E-115 neuroblastoma cells during lysophosphatidic acid-induced, Rho-mediated neurite retraction. This phosphorylation was sensitive to Y-27632, a specific inhibitor of the Rho-associated kinase ROCK. ROCK, which is a downstream effector of Rho, did not phosphorylate cofilin directly but phosphorylated LIM-kinase, which in turn was activated to phosphorylate cofilin. Overexpression of LIM-kinase in HeLa cells induced the formation of actin stress fibers in a Y-27632-sensitive manner. These results indicate that phosphorylation of LIM-kinase by ROCK and consequently increased phosphorylation of cofilin by LIM-kinase contribute to Rho-induced reorganization of the actin cytoskeleton.