title: L-NAME-induced dispersion of melanosomes in melanophores activates PKC, MEK and ERK1.
abstract: Melanosome movement represents a good model of cytoskeleton-mediated transport of organelles in eukaryotic cells. We recently observed that inhibiting nitric oxide synthase (NOS) with Nomega-nitro-L-arginine methyl ester (L-NAME) induced dispersion in melanophores pre-aggregated with melatonin. Activation of cyclic adenosine 3',5'-monophosphate (cAMP)-dependent protein kinase (PKA) or calcium-dependent protein kinase (PKC) is known to cause dispersion. Also, PKC and NO have been shown to regulate the mitogen/extracellular signal-regulated kinase (MEK)-ERK pathway. Accordingly, our objective was to further characterize the signaling pathway of L-NAME-induced dispersion. We found that the dispersion was decreased by staurosporine and PD98059, which respectively inhibit PKC and MEK, but not by the PKA inhibitor H89. Furthermore, Western blotting revealed that ERK1 kinase was phosphorylated in L-NAME-dispersed melanophores. L-NAME also caused dispersion in latrunculin-B-treated cells, suggesting that this effect is not due to inhibition of the melatonin signaling pathway. Summarizing, we observed that PKC and MEK inhibitors decreased the L-NAME-induced dispersion, which caused phosphorylation of ERK1. Our results also suggest that NO is a negative regulator of phosphorylations that leads to organelle transport.
authors.affiliation: Department of Health and Environment, Faculty of Health Sciences, University of Linköping, Sweden.
authors.forename: H M
authors.initials: HM
authors.lastname: Nilsson
authors.forename: S P
authors.initials: SP
authors.lastname: Svensson
authors.forename: T
authors.initials: T
authors.lastname: Sundqvist
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048369:MAP Kinase Kinase 1; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D008547:Melanophores / Q000187:drug effects / Q000201:enzymology*; D020460:Melanosomes / Q000187:drug effects / Q000201:enzymology*; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases / Q000187:drug effects / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism; D020409:Molecular Motor Proteins / Q000187:drug effects / Q000502:physiology*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D015388:Organelles / Q000187:drug effects / Q000502:physiology*; D011493:Protein Kinase C / Q000187:drug effects / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000187:drug effects / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology*; D014982:Xenopus laevis
chemical_list: D004791:Enzyme Inhibitors; D020409:Molecular Motor Proteins; D009569:Nitric Oxide; D017346:Protein Serine-Threonine Kinases; D011493:Protein Kinase C; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases; D019331:NG-Nitroarginine Methyl Ester