mVps45 knockdown selectively modulates VAMP expression in 3T3-L1 adipocytes

Sadler, Jessica B A and Roccisana, Jennifer and Virolainen, Minttu and Bryant, Nia J. and Gould, Gwyn W. (2015) mVps45 knockdown selectively modulates VAMP expression in 3T3-L1 adipocytes. Communicative and Integrative Biology, 8 (3). ISSN 1942-0889

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    Abstract

    Insulin stimulates the delivery of glucose transporter-4 (GLUT4)-containing vesicles to the surface of adipocytes. Depletion of the Sec1/Munc18 protein mVps45 significantly abrogates insulin-stimulated glucose transport and GLUT4 translocation. Here we show that depletion of mVps45 selectively reduced expression of VAMPs 2 and 4, but not other VAMP isoforms. Although we did not observe direct interaction of mVps45 with any VAMP isoform; we found that the cognate binding partner of mVps45, Syntaxin 16 associates with VAMPs 2, 4, 7 and 8 in vitro. Co-immunoprecipitation experiments in 3T3-L1 adipocytes revealed an interaction between Syntaxin 16 and only VAMP4. We suggest GLUT4 trafficking is controlled by the coordinated expression of mVps45/Syntaxin 16/VAMP4, and that depletion of mVps45 regulates VAMP2 levels indirectly, perhaps via reduced trafficking into specialized subcellular compartments.