title: Calcium influx and membrane depolarization induce phosphorylation of neurofilament (NF-M) KSP repeats in PC12 cells.
abstract: Signals activating the kinases that phosphorylate neurofilament proteins in the axon remain unknown. In a previous study, we have demonstrated that a constitutively active form of MEK1 activates Erk1 and Erk2 kinases, which phosphorylate co-transfected NF-M in NIH 3T3 cells. In this study, we report the activation of endogenous Erk1 and Erk2 by membrane depolarization and calcium influx through L-type calcium channels, which resulted in phosphorylation of the NF-M tail domain in PC12 cells. This phosphorylation was inhibited in the presence of nifedipine, an L-type calcium channel inhibitor, and PD98059, a specific MEK1 inhibitor. Our data suggest a mechanism linking calcium influx through voltage-gated calcium channels with the MAP kinase pathway and NF-M tail domain phosphorylation in cell body and neurite. These findings may provide significant new insights into mechanisms involved in some neurological diseases.
authors.affiliation: Laboratory of Neurochemistry, NINDS, NIH, Bldg. 36, Rm. 4D20, 9000 Rockville Pike, Bethesda, MD 20892-4130, USA.
authors.forename: B S
authors.initials: BS
authors.lastname: Li
authors.lastname: Veeranna
authors.forename: P
authors.initials: P
authors.lastname: Grant
authors.forename: H C
authors.initials: HC
authors.lastname: Pant
mesh_terms: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002120:Calcium Channel Agonists / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D020746:Calcium Channels, L-Type; D020013:Calcium Signaling / Q000502:physiology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D015640:Ion Channel Gating / Q000187:drug effects; D017136:Ion Transport / Q000187:drug effects; D008564:Membrane Potentials; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D009363:Neoplasm Proteins / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D016501:Neurites / Q000648:ultrastructure; D016900:Neurofilament Proteins / Q000378:metabolism*; D009543:Nifedipine / Q000494:pharmacology; D016716:PC12 Cells; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection
chemical_list: D002120:Calcium Channel Agonists; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D004791:Enzyme Inhibitors; D005419:Flavonoids; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D016900:Neurofilament Proteins; D011993:Recombinant Fusion Proteins; C061195:neurofilament protein M; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D009543:Nifedipine; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D002118:Calcium