title: Eicosanoid activation of protein kinase C epsilon: involvement in growth cone repellent signaling.
abstract: Exposure of growing neurons to thrombin or semaphorin 3A stimulates a receptor-mediated signaling cascade that results in collapse of their growth cones. This collapse response necessitates eicosanoid production, as we have shown earlier. The present report investigates whether and which protein kinase C (PKC) isoforms may be activated by such eicosanoids. To examine these questions, we isolated growth cones from fetal rat brain and tested whether thrombin or the eicosanoid, 12(S)-hydroxyeicosatetraenoic acid (12(S)-HETE), could activate endogenous growth cone PKC. We show that both thrombin and 12(S)-HETE stimulate the phosphorylation of the myristoylated alanine-rich protein kinase C substrate, an 87-kDa adhesion site protein. Furthermore, we show both with immunoprecipitated and with recombinant PKC that 12(S)-HETE activation is selective for the epsilon isoform and does not require accessory proteins. Last, we demonstrate that PKC activation is necessary for thrombin-induced growth cone collapse. These data indicate that eicosanoid-mediated repellent effects result from the direct and selective activation of PKCepsilon and suggest the involvement of myristoylated alanine-rich protein kinase C substrate phosphorylation in growth cone collapse.
authors.affiliation: Department of Cellular and Structural Biology and University of Colorado Cancer Center, University of Colorado School of Medicine, Denver, Colorado 80262, USA.
authors.forename: Keith
authors.initials: K
authors.lastname: Mikule
authors.forename: Somkiat
authors.initials: S
authors.lastname: Sunpaweravong
authors.forename: Jesse C
authors.initials: JC
authors.lastname: Gatlin
authors.forename: Karl H
authors.initials: KH
authors.lastname: Pfenninger
mesh_terms: D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid / Q000494:pharmacology*; D000818:Animals; D002448:Cell Adhesion / Q000502:physiology; D004789:Enzyme Activation / Q000187:drug effects; D020439:Growth Cones / Q000187:drug effects* / Q000201:enzymology*; D006490:Hemostatics / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D009474:Neurons / Q000201:enzymology / Q000648:ultrastructure; D010766:Phosphorylation; D011233:Precipitin Tests; D011493:Protein Kinase C / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D051744:Protein Kinase C-epsilon; D011506:Proteins / Q000378:metabolism; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D013917:Thrombin / Q000494:pharmacology
chemical_list: D006490:Hemostatics; D047908:Intracellular Signaling Peptides and Proteins; C000619712:Marcks protein, rat; D008565:Membrane Proteins; D011506:Proteins; D011994:Recombinant Proteins; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; C497257:Prkce protein, rat; D011493:Protein Kinase C; D051744:Protein Kinase C-epsilon; D013917:Thrombin