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L-NAME-induced dispersion of melanosomes in melanophores activates PKC, MEK and ERK1
Linköping University, Department of Molecular and Clinical Medicine, Medical Microbiology. Linköping University, Faculty of Health Sciences.
Linköping University, Department of Medicine and Care, Pharmacology. Linköping University, Faculty of Health Sciences.
Linköping University, Department of Molecular and Clinical Medicine, Medical Microbiology. Linköping University, Faculty of Health Sciences.
2001 (English)In: Pigment Cell Research, ISSN 0893-5785, E-ISSN 1755-148X, Vol. 14, no 6, 450-455 p.Article in journal (Refereed) Published
Abstract [en]

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 Nω-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.

Place, publisher, year, edition, pages
2001. Vol. 14, no 6, 450-455 p.
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-26064DOI: 10.1034/j.1600-0749.2001.140605.xLocal ID: 10523OAI: oai:DiVA.org:liu-26064DiVA: diva2:246612
Note

On the day of the defence day the status of this article was a manuscript.

Available from: 2009-10-08 Created: 2009-10-08 Last updated: 2015-09-18Bibliographically approved
In thesis
1. The role of nitric oxide in cytoskeleton-mediated organelle transport and cell adhesion
Open this publication in new window or tab >>The role of nitric oxide in cytoskeleton-mediated organelle transport and cell adhesion
2001 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Nitric oxide (NO) is a signaling molecule that is produced by many different kinds of cells, and it is known to mediate actions such as blood vessel dilation, communication between nerve cells, and killing of bacteria in infections. The cytoskeleton is involved in many important cellular functions, among them intracellular transport of organelles, migration, and cell division. The aim of the present studies was to examine the effects of NO on some of the indicated functions. Homotypic adhesion of human neutrophils, which is mediated by ß2 integrins, is an early step in the inflammatory process. Addition of L-argiriine (the substrate of NO production) to fMLP-stimulated neutrophils increased and prolonged aggregation of the cells. Stimulation of L-arginine-pretreated neutrophils by cross-linking of ß2 integrins attenuated the increase in F-actin, as compared to control cells. These results suggest that the aggregation is prolonged by activation of ß2 integrins and endogenous NO production, two events that together seem to inhibit actin polymerization, possibly via ADP ribosylation.

The effect of NO on intracellular translocation of organelles along the cytoskeleton was studied in Xenopus laevis pigment cells. Inhibition of NO production induced by the drug L-NAME was found to inhibit aggregation of the pigment organelles (melanosomes) and to induce dispersion. Activation of PKC, MEK, and ERKl, but not PKA, was associated with the dispersion, thus NO may negatively regulate these kinases, which, when activated, would induce movement of melanosomes. During melanosome aggregation, the cell center increases in height by approximately 30%. Experiments were performed to determine whether the cell membrane is pushed upwards by actin polymerization and water influx through HgCl2-sensitive aquaporins. The results gave no evidence that either two of these mechanisms affects the upward movement. However, L-NAME caused dispersion and a decrease in cell height, thus NO may play a role in maintaining an aggregated, elevated state. In conclusion, many factors regulate both homotypic aggregation and intracellular organelle transport, and NO seems to prolong homotypic aggregation of neutrophils and regulate melanosome transport by inhibiting PKC, MEK and ERKl.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet, 2001. 48 p.
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 660
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-28614 (URN)13769 (Local ID)91-7219-761-7 (ISBN)13769 (Archive number)13769 (OAI)
Public defence
2001-03-02, Elsa Brändströmssalen, Universitetssjukhuset, Linköping, 09:00 (Swedish)
Opponent
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2015-09-18Bibliographically approved

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Nilsson, Harriet M.Svensson, SamuelSundqvist, Tommy

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