Rab32 Regulates Melanosome Transport in Xenopus Melanophores by Protein Kinase A Recruitment

Minjong Park, Anna S. Serpinskaya, Nancy Papalopulu, Vladimir I. Gelfand*

*Corresponding author for this work

Research output: Contribution to journalArticle

33 Scopus citations

Abstract

Intracellular transport is essential for cytoplasm organization, but mechanisms regulating transport are mostly unknown. In Xenopus melanophores, melanosome transport is regulated by cAMP-dependent protein kinase A (PKA) [1]. Melanosome aggregation is triggered by melatonin, whereas dispersion is induced by melanocyte-stimulating hormone (MSH) [2]. The action of hormones is mediated by cAMP: High cAMP in MSH-treated cells stimulates PKA, whereas low cAMP in melatonin-treated cells inhibits it. PKA activity is typically restricted to specific cell compartments by A-kinase anchoring proteins (AKAPs) [3]. Recently, Rab32 has been implicated in protein trafficking to melanosomes [4] and shown to function as an AKAP on mitochondria [5]. Here, we tested the hypothesis that Rab32 is involved in regulation of melanosome transport by PKA. We demonstrated that Rab32 is localized to the surface of melanosomes in a GTP-dependent manner and binds to the regulatory subunit RIIα of PKA. Both RIIα and Cβ subunits of PKA are required for transport regulation and are recruited to melanosomes by Rab32. Overexpression of wild-type Rab32, but not mutants unable to bind PKA or melanosomes, inhibits melanosome aggregation by melatonin. Therefore, in melanophores, Rab32 is a melanosome-specific AKAP that is essential for regulation of melanosome transport.

Original languageEnglish (US)
Pages (from-to)2030-2034
Number of pages5
JournalCurrent Biology
Volume17
Issue number23
DOIs
StatePublished - Dec 4 2007

Keywords

  • CELLBIO
  • SIGNALING

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)

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