Protein‐Kinase C Mediates MCH Signal Transduction in Teleost, Synbranchus marmoratus, Melanocytes

MARIA SILVIA ABRÃO, ANA MARIA DE L. CASTRUCCI, MAC E. HADLEY, VICTOR J. HRUBY

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

MCH (melanin concentrating hormone) is a heptadecapeptide, Asp‐Thr‐Met‐Arg‐Cys‐Met‐Val‐Gly‐Arg‐Val‐Tyr‐Arg‐Pro‐Cys‐Tip‐Glu‐Val, which stimulates melanosome (melanin granule) aggregation to a perinuclear position within teleost fish integumental melanocytes, resulting in lightening of the skin. The mechanisms of action of MCH are unknown. Drugs that affect the diacylglycerol/inositol triphosphate pathway were used to investigate the possible roles of this pathway in the mechanisms of action of MCH on Synbranchus marmoratus (teleost) melanocytes. The shift of the dose‐response curve to MCH in the presence of various concentrations of 4‐bromophenacyl bromide and neomycin sulphate, phospholipase C inhibitors, suggests that phospholipase C is stimulated after MCH receptor activation. Low concentrations (10−9 to 10−8 M) of the phorbol ester TPA exhibited MCH‐like activity, eliciting a dose‐dependent melanosome aggregation. Higher doses, however, displaced to the right the dose‐response curve to MCH, as did the protein kinase C inhibitors, dibucaine and 1‐(5‐isoquinolinylsulfonyl)‐2‐methylpiperazine (H‐7). These results support the assumption that protein kinase C mediates the pigment aggregating activity of MCH. Both MCH and norepinephrine lightening actions were abolished by beta‐glycerophosphate, a phosphatase inhibitor, suggesting that a protein dephosphorylation occurs during melanosome aggregation, and is, therefore, a common event triggered by MCH and norepinephrine, although both agonists act through separate receptors and exhibit different transduction mechanisms.

Original languageEnglish (US)
Pages (from-to)66-70
Number of pages5
JournalPigment Cell Research
Volume4
Issue number2
DOIs
StatePublished - Mar 1991

Keywords

  • Diacylglycerol/inositol triphosphate pathway
  • Melanin concentrating hormone (MCH)
  • Melanocytes
  • Melanophores
  • Protein kinase C

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Plant Science
  • Developmental Biology
  • Clinical Biochemistry
  • Cell Biology

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