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

Authors: Imai, A  Ishida, M  Fukuda, M  Nashida, T  Shimomura, H 
Citation: Imai A, etal., Arch Biochem Biophys. 2013 Aug 1;536(1):31-7. doi: 10.1016/j.abb.2013.05.002. Epub 2013 May 20.
Pubmed: (View Article at PubMed) PMID:23702376
DOI: Full-text: DOI:10.1016/j.abb.2013.05.002

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.

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CRRD Object Information
CRRD ID: 9588639
Created: 2014-11-03
Species: All species
Last Modified: 2014-11-03
Status: ACTIVE



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RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.