title: A novel cyathane diterpene, cyrneine A, induces neurite outgrowth in a Rac1-dependent mechanism in PC12 cells.
abstract: We examined the effects of cyrneine A, a novel diterpene isolated from the mushroom Sarcodon cyrneus, on morphology of rat pheochromocytoma cells (PC12). In response to cyrneine A, PC12 cells extended their neurites, an effect partially blocked by the extracellular signal-regulated kinase (ERK) kinase inhibitor PD98059, but not by the protein kinase C inhibitor GF109203X, nor the phosphatidylinositol-3-kinase inhibitor wortmannin. Cyrneine A did not activate ERK at any of the time points tested (5-120 min), indicating that only the basal activity of ERK is required for cyrneine A-induced neurite outgrowth. As transcriptional regulation is required for neurite extension, the activity of three major transcription factors was determined. Cyrneine A enhanced activation of the transcription factors activator protein-1 (AP-1) and nuclear factor-kappaB, but not CREB, and this was accompanied by enhanced c-fos expression. Moreover, we determined the role of Rac1, a small GTPase protein of the Rho family that regulates actin dynamics, in cyrneine A-induced neurite outgrowth. Treatment with cyrneine A led to actin translocation and subsequently, to accumulation of F-actin at the tip of neurites. Rac1 activity was increased by cyrneine A and expression of a dominant-negative Rac1 mutant significantly inhibited the cyrneine A-induced extension of neurites. These results suggest that cyrneine A induces neurite outgrowth in a Rac1-dependent mechanism.
authors.affiliation: Department of Cellular Signaling and 21st COE program CRESCENDO, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba, Aramaki, Sendai, Miyagi, Japan. obaray@mail.pharm.tohoku.ac.jp
authors.forename: Yutaro
authors.initials: Y
authors.lastname: Obara
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Hoshino
authors.forename: Maria Carla
authors.initials: MC
authors.lastname: Marcotullio
authors.forename: Rita
authors.initials: R
authors.lastname: Pagiotti
authors.forename: Norimichi
authors.initials: N
authors.lastname: Nakahata
mesh_terms: D000199:Actins / Q000378:metabolism*; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D001487:Basidiomycota / Q000737:chemistry; D004224:Diterpenes / Q000737:chemistry / Q000494:pharmacology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D007211:Indoles / Q000494:pharmacology; D008301:Maleimides / Q000494:pharmacology; D009154:Mutation; D016501:Neurites / Q000378:metabolism*; D016716:PC12 Cells; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D021381:Protein Transport / Q000187:drug effects; D051381:Rats; D014157:Transcription Factors / Q000378:metabolism*; D000077191:Wortmannin; D020830:rac1 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*
chemical_list: D000199:Actins; D000730:Androstadienes; D004224:Diterpenes; D007211:Indoles; D008301:Maleimides; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D014157:Transcription Factors; C514905:cyrneine A; D011493:Protein Kinase C; D048049:Extracellular Signal-Regulated MAP Kinases; D020830:rac1 GTP-Binding Protein; C070515:bisindolylmaleimide I; D000077191:Wortmannin