title: Erk1/2- and p38 MAP kinase-dependent phosphorylation and activation of cPLA2 by m3 and m2 receptors.
abstract: This study examined the upstream signaling pathways initiated by muscarinic m2 and m3 receptors that mediate sustained ERK1/2- and p38 MAP kinase-dependent phosphorylation and activation of the 85-kDa cytosolic phospholipase (cPL)A(2) in smooth muscle. The pathway initiated by m2 receptors involved sequential activation of Gbetagamma(i3), phosphatidylinositol (PI)3-kinase, Cdc42, and Rac1, p21-activated kinase (PAK1), p38 mitogen-activated protein (MAP) kinase, and cPLA(2), and phosphorylation of cPLA(2) at Ser(505). cPLA(2) activity was inhibited to the same extent (61 +/- 5 to 72 +/- 4%) by the m2 antagonist methoctramine, Gbeta antibody, pertussis toxin, the PI3-kinase inhibitor LY 294002, PAK1 antibody, the p38 MAP kinase inhibitor SB-203580, and a Cdc42/Rac1 GEF (Vav2) antibody and by coexpression of dominant-negative Cdc42 and Rac1 mutants. The pathway initiated by m3 receptors involved sequential activation of Galpha(q), PLC-beta1, PKC, ERK1/2, and cPLA(2), and phosphorylation of cPLA(2) at Ser(505). cPLA(2) activity was inhibited to the same extent (35 +/- 3 to 41 +/- 5%) by the m3 antagonist 4-diphenylacetoxy-N-methylpiperdine (4-DAMP), the phosphoinositide hydrolysis inhibitor U-73122, the PKC inhibitor bisindolylmaleimide, and the ERK1/2 inhibitor PD 98059. cPLA(2) activity was not affected in cells coexpressing dominant-negative RhoA and PLC-delta1 mutants, implying that PKC was not derived from phosphatidylcholine hydrolysis. The effects of ERK1/2 and p38 MAP kinase on cPLA(2) activity were additive and accounted fully for activation and phosphorylation of cPLA(2).
authors.affiliation: Departments of Physiology and Medicine, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA 23298, USA.
authors.forename: Huiping
authors.initials: H
authors.lastname: Zhou
authors.forename: Sankar
authors.initials: S
authors.lastname: Das
authors.forename: Karnam S
authors.initials: KS
authors.lastname: Murthy
mesh_terms: D000109:Acetylcholine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D004789:Enzyme Activation; D019204:GTP-Binding Proteins / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009130:Muscle, Smooth / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010739:Phospholipase D / Q000378:metabolism; D010741:Phospholipases A / Q000378:metabolism*; D010766:Phosphorylation; D010880:Piperidines / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011817:Rabbits; D043585:Receptor, Muscarinic M2; D043587:Receptor, Muscarinic M3; D011976:Receptors, Muscarinic / Q000378:metabolism*; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D054462:p21-Activated Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
chemical_list: D000109:Acetylcholine; D019204:GTP-Binding Proteins; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D010739:Phospholipase D; D010741:Phospholipases A; D010880:Piperidines; D017346:Protein Serine-Threonine Kinases; D043585:Receptor, Muscarinic M2; D043587:Receptor, Muscarinic M3; D011976:Receptors, Muscarinic; D012694:Serine; D020764:cdc42 GTP-Binding Protein; D054462:p21-Activated Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D020830:rac1 GTP-Binding Protein; C042375:4-diphenylacetoxy-1,1-dimethylpiperidinium