title: Translocation and association of ROCK-II with RhoA and HSP27 during contraction of rabbit colon smooth muscle cells.
abstract: The focus of the paper is to understand the role of HSP27 in mediating the association of RhoA with ROCK-II in sustained contraction of smooth muscle cells from the rabbit colon. In circular smooth muscle cells; acetylcholine-induced contraction (10(-7)M) was associated with translocation of ROCK-II to the particulate fraction, which remained sustained at 4 min after stimulation (135.1+/-8.1% increase, P </= 0.05). There was also an increased association of ROCK-II with RhoA particulate fraction (147.46+/-9.31 and 148.22+/-9.41, n = 3, P </= 0.05) and with HSP27 (155.6+/-10.7% increase, P </= 0.05) in the particulate fraction. Pre-incubation of cells with Y27632 resulted in the inhibition of the association of ROCK-II with RhoA in the particulate fraction. Acetylcholine (10(-7)M) induced sustained phosphorylation of MLC (122.75+/-9.97%, P </= 0.05 and 174.65+/-28.36%, P </= 0.05 increase in the di phospho-MLC at 30s and 4 min, respectively), which was inhibited upon pre-incubation with Y27632. Results suggest that ROCK-II undergoes a translocation to the particulate fraction with RhoA and with HSP27, suggesting that translocation and association of ROCK-II with RhoA is mediated by HSP27. Maintenance of the functional association of RhoA with ROCK-II in the particulate fraction mediated by HSP27 appears to be important to retain MLC in the phosphorylated state and hence the sustained contraction.
authors.affiliation: Department of Pediatrics, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Suresh B
authors.initials: SB
authors.lastname: Patil
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Tsunoda
authors.forename: Mercy D
authors.initials: MD
authors.lastname: Pawar
authors.forename: Khalil N
authors.initials: KN
authors.lastname: Bitar
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western; D003106:Colon / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D006360:Heat-Shock Proteins / Q000737:chemistry*; D047908:Intracellular Signaling Peptides and Proteins; D008954:Models, Biological; D009119:Muscle Contraction; D009130:Muscle, Smooth / Q000166:cytology*; D009363:Neoplasm Proteins / Q000737:chemistry*; D010766:Phosphorylation; D011233:Precipitin Tests; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000378:metabolism; D021381:Protein Transport; D011725:Pyridines / Q000737:chemistry; D011817:Rabbits; D013997:Time Factors; D014162:Transfection; D014665:Vasodilator Agents / Q000737:chemistry; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein / Q000737:chemistry* / Q000378:metabolism
chemical_list: D006360:Heat-Shock Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009363:Neoplasm Proteins; D011725:Pyridines; D014665:Vasodilator Agents; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein; D000109:Acetylcholine