title: HSP27 modulates agonist-induced association of translocated RhoA and PKC-alpha in muscle cells of the colon.
abstract: The recruitment of signal transduction molecules to the membrane is crucial for the efficient coupling of extracellular signals and contractile response. The trafficking is dynamic. We have investigated a possible cross talk between agonist-induced association of translocated RhoA and translocated protein kinase C-alpha (PKC-alpha) and a role for heat shock protein 27 (HSP27) in mediating this interaction. Immunoprecipitation with HSP27 monoclonal antibody followed by immunoblotting with either RhoA antibody or PKC-alpha antibody indicated that acetylcholine induced associations of HSP27-RhoA and HSP27-PKC-alpha in the membrane fraction but not in the cytosolic fraction. Immunoprecipitation with anti-RhoA monoclonal antibody followed by immunoblotting with PKC-alpha antibody indicated that acetylcholine induced a significant complexing of RhoA-PKC-alpha in the membrane fraction but not in the cytosolic fraction. In summary, the data indicate that agonist-induced contraction is associated with 1) association of translocated RhoA with HSP27 on the membrane, 2) association of translocated PKC-alpha with HSP27 on the membrane, and 3) association of PKC-alpha with RhoA on the membrane. The data suggest an important role for HSP27 in modulating a multiprotein complex that includes translocated RhoA and PKC-alpha.
authors.affiliation: Department of Pediatrics, University of Michigan Medical Center, Ann Arbor, Michigan 48109, USA. bitar@umich.edu
authors.forename: K N
authors.initials: KN
authors.lastname: Bitar
authors.forename: A
authors.initials: A
authors.lastname: Ibitayo
authors.forename: S B
authors.initials: SB
authors.lastname: Patil
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D015153:Blotting, Western; D002518:Ceramides / Q000494:pharmacology; D003106:Colon / Q000166:cytology / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000235:genetics / Q000502:physiology*; D009130:Muscle, Smooth / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000235:genetics / Q000502:physiology*; D011233:Precipitin Tests; D011493:Protein Kinase C / Q000235:genetics / Q000502:physiology*; D051571:Protein Kinase C-alpha; D011817:Rabbits; D015398:Signal Transduction / Q000502:physiology; D014178:Translocation, Genetic / Q000235:genetics; D020742:rhoA GTP-Binding Protein / Q000235:genetics / Q000502:physiology*
chemical_list: D000911:Antibodies, Monoclonal; D002518:Ceramides; D007527:Isoenzymes; D009363:Neoplasm Proteins; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D020742:rhoA GTP-Binding Protein; D000109:Acetylcholine