title: Melatonin activates PKC-alpha but not PKC-epsilon in N1E-115 cells.
abstract: Previous reports have revealed that calmodulin antagonism by melatonin is followed by microtubule enlargements and neurite outgrowths in neuroblastoma N1E-115 cells. In addition, activation of protein kinase C (PKC) by this neurohormone is also followed by increased vimentin phosphorylation, and reorganization of vimentin intermediate filaments (IFs) in N1E-115 cells. In this work, we further characterize the activation of PKC by melatonin in neuroblastoma N1E-115 cells. We studied the Ca(2+)-dependent effects of melatonin on PKC activity and distribution of PKC-alpha in isolated N1E-115 cell IFs. Also, the effects of melatonin on PKC-alpha translocation in comparison to PKC-epsilon, were studied in intact N1E-115 cells. The results showed that both melatonin and the PKC agonist phorbol-12-myristate-13-acetate increased PKC activity in isolated IFs. The effects of the hormone were Ca(2+)-dependent, while those caused by the phorbol ester were produced with or without Ca(2+). Also, in isolated in situ IFs, the hormone changed the distribution of PKC-alpha. In intact N1E-115 cells, melatonin elicited PKC-alpha translocation and no changes were detected in PKC-epsilon. Phorbol-12-myristate-13-acetate modified the subcellular distribution of both PKC isoforms. The results showed that melatonin selectively activates the Ca(2+)-dependent alpha isoform of PKC and suggest that PKC-alpha activation by melatonin underlies IF rearrangements and participates in neurite formation in N1E-115 cells.
authors.affiliation: Departamento de Neurofarmacología, SIC, Instituto Nacional de Psiquiatría, Ramón de la Fuente Muñiz, Calz México-Xochimilco No 101, CP 14370, Col. San Lorenzo Huipulco, D.F., Mexico. bekin@imp.edu.mx
authors.forename: G
authors.initials: G
authors.lastname: Benítez-King
authors.forename: M E
authors.initials: ME
authors.lastname: Hernández
authors.forename: R
authors.initials: R
authors.lastname: Tovar
authors.forename: G
authors.initials: G
authors.lastname: Ramírez
mesh_terms: D000818:Animals; D002460:Cell Line; D004789:Enzyme Activation; D007382:Intermediate Filaments / Q000201:enzymology / Q000378:metabolism / Q000648:ultrastructure; D007527:Isoenzymes / Q000378:metabolism*; D008550:Melatonin / Q000494:pharmacology*; D051379:Mice; D008854:Microscopy, Electron; D015240:Phorbol 12,13-Dibutyrate / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism*; D051571:Protein Kinase C-alpha; D051744:Protein Kinase C-epsilon; D021381:Protein Transport; D014316:Tritium; D014407:Tumor Cells, Cultured
chemical_list: D007527:Isoenzymes; D014316:Tritium; D015240:Phorbol 12,13-Dibutyrate; C497256:Prkce protein, mouse; C496630:Prkca protein, mouse; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; D051744:Protein Kinase C-epsilon; D008550:Melatonin