title: Promotion of neurite outgrowth by protein kinase inhibitors and ganglioside GM1 in neuroblastoma cells involves MAP kinase ERK1/2.
abstract: To investigate mechanisms of neurite outgrowth, murine Neuro-2a neuroblastoma cells were exposed to ganglioside GM1 in the presence or absence of specific protein kinase inhibitors. Isoquinolinesulfonamide (H-89), an inhibitor of cyclic AMP dependent protein kinase A (PKA), and bisindolylmaleimide I (BIM), which inhibits protein kinase C, each stimulated neurite outgrowth in a dose-dependent manner in the absence of exogenous GM1. Minimally effective (threshold) concentrations of H-89 or BIM potentiated outgrowth when they were used in combination with GM1. To search for a shared component in the mechanisms of GM1, H-89 and BIM, phosphorylation of ERK1/2 was examined. Inhibition of the activation of extracellular signal regulated kinases (ERK1/2) by U0126, prevented neuritogenesis of Neuro-2a by all the three agents. Pretreatment of serum-depleted Neuro-2a cultures with GM1 or BIM enhanced ERK1/2 phosphorylation when the serum level was restored to 10%. In contrast, H-89 did not alter the serum-mediated response. In cells exposed to GM1 or BIM without additional serum, a transitory decrease in ERK phosphorylation occurred. These data suggest that GM1 influences two neuritogenic pathways, one modulated by PKC and the other regulated by PKA. Therefore, GM1 may have the potential to stimulate alternate pathways resulting in outgrowth.
authors.affiliation: Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, KY 40292, USA.
authors.forename: D W
authors.initials: DW
authors.lastname: Singleton
authors.forename: C L
authors.initials: CL
authors.lastname: Lu
authors.forename: R
authors.initials: R
authors.lastname: Colella
authors.forename: F J
authors.initials: FJ
authors.lastname: Roisen
mesh_terms: D000818:Animals; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005677:G(M1) Ganglioside / Q000494:pharmacology*; D007211:Indoles / Q000494:pharmacology; D007546:Isoquinolines / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D008301:Maleimides / Q000494:pharmacology; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D016501:Neurites / Q000201:enzymology*; D009447:Neuroblastoma; D010766:Phosphorylation; D013449:Sulfonamides; D014407:Tumor Cells, Cultured
chemical_list: D004791:Enzyme Inhibitors; D007211:Indoles; D007546:Isoquinolines; D008301:Maleimides; D013449:Sulfonamides; D005677:G(M1) Ganglioside; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide; C088060:bisindolylmaleimide