title: Potentiation of nerve growth factor-induced neurite outgrowth by the ROCK inhibitor Y-27632: a possible role of IP₃ receptors.
abstract: ROCK, a serine/threonine protein kinase that has been identified as a Rho GTP-binding protein, is a promising target for neuropsychiatric disorders. The selective ROCK inhibitor Y-27632 has been shown to induce neurite outgrowth in PC12 cells. However, the precise cellular and molecular mechanisms underlying ROCK inhibition-induced neurite outgrowth are not fully understood. In this study, we examined the roles of cellular signaling pathways in the potentiation of nerve growth factor (NGF)-induced neurite outgrowth by Y-27632. Y-27632 significantly potentiated NGF (2.5 ng/ml)-induced neurite outgrowth in PC12 cells, in a concentration-dependent manner. Furthermore, another ROCK inhibitor, H-1152, and the Rho inhibitor botulinum exoenzyme C3 also potentiated NGF (2.5 ng/ml)-induced neurite outgrowth. The effects by Y-27632 were antagonized by co-administration of inositol 1,4,5-trisphosphate (IP(3)) receptor antagonists (xestospongin C or 2-aminoethoxydiphenylborate (2-APB)). Moreover, the potentiation by Y-27632 was blocked by co-administration of the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 or an Akt inhibitor. In contrast, the specific inhibitors of phospholipase C (PLC-γ), p38MAPK, c-Jun N-terminal kinase (JNK), and the Ras/Raf/mitogen-activated protein kinase (MAPK) signaling pathways did not affect the potentiation of NGF-induced neurite outgrowth by Y-27632. The results of double-staining immunocytochemistry suggested that both ROCK1 and type-1 IP₃ receptors may be co-localized in the cell body of PC12 cells. In conclusion, these findings suggest that IP₃ receptors and PI3K-Akt signaling pathways might be involved in the mechanisms of potentiation of NGF-induced neurite outgrowth by ROCK inhibitors.
authors.affiliation: Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Inohana, Chiba, Japan.
authors.forename: Takahiko
authors.initials: T
authors.lastname: Minase
authors.forename: Tamaki
authors.initials: T
authors.lastname: Ishima
authors.forename: Kanako
authors.initials: K
authors.lastname: Itoh
authors.forename: Kenji
authors.initials: K
authors.lastname: Hashimoto
mesh_terms: D000577:Amides / Q000494:pharmacology*; D000818:Animals; D004357:Drug Synergism; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects; D020932:Nerve Growth Factor / Q000494:pharmacology*; D016501:Neurites / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism*; D016716:PC12 Cells; D010879:Piperazines / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011725:Pyridines / Q000494:pharmacology*; D051381:Rats; D020917:Receptor, trkA / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000037:antagonists & inhibitors; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors*
chemical_list: D000577:Amides; D053496:Inositol 1,4,5-Trisphosphate Receptors; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D011725:Pyridines; C108830:Y 27632; D020932:Nerve Growth Factor; C101789:SA 4503; D020917:Receptor, trkA; D054460:rho-Associated Kinases; D020741:rho GTP-Binding Proteins