MADD/DENN/Rab3GEP functions as a guanine nucleotide exchange factor for Rab27 during granule exocytosis of rat parotid acinar cells

Akane Imai, Morié Ishida, Mitsunori Fukuda, Tomoko Nashida, Hiromi Shimomura

    Research output: Contribution to journalArticlepeer-review

    10 Citations (Scopus)

    Abstract

    We previously reported that the small GTPase Rab27 and its effectors regulate isoproterenol (IPR)-stimulated amylase release from rat parotid acinar cells. Although activation of Rab27 by a specific guanine nucleotide exchange factor (GEF) is thought to be required for amylase release, its activation mechanism is poorly understood, because GEF for Rab27 has not been reported in parotid acinar cells. In the present study, we investigated the possible involvement of MADD/DENN/Rab3GEP, which was recently described as a Rab27-GEF in melanocytes, in amylase release from rat parotid acinar cells. Reverse transcription-PCR analyses indicated that mRNA of DENND family members, including MADD, was expressed in parotid acinar cells. MADD protein was also expressed in the cytosolic fraction of parotid acinar cells. Incubation of an antibody against the C-terminal 150 amino acids of MADD (anti-MADD-C antibody) with streptolysin O-permeabilized parotid acinar cells caused not only inhibition of IPR-induced amylase release but also reduction in the amount of GTP-Rab27. Our findings indicated that MADD functions as a GEF for Rab27 in parotid acinar cells and that its GEF activity for Rab27, i.e., GDP/GTP cycling, is required for IPR-induced amylase release.

    Original languageEnglish
    Pages (from-to)31-37
    Number of pages7
    JournalArchives of Biochemistry and Biophysics
    Volume536
    Issue number1
    DOIs
    Publication statusPublished - 2013

    Keywords

    • Amylase release
    • DENND family
    • Guanine nucleotide exchange factor
    • MADD
    • Parotid acinar cells
    • Rab27

    ASJC Scopus subject areas

    • Biophysics
    • Biochemistry
    • Molecular Biology

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