Proteomic Analysis of GLUT4 Storage Vesicles Reveals Tumour Suppressor Candidate 5 (TUSC5) as a Novel Regulator of Insulin Action in Adipocytes

Daniel J Fazakerley, Sheyda Naghiloo, Rima Chaudhuri, Francoise Koumanov, James G Burchfield, Kristen C Thomas, James R Krycer, Matthew J Prior, Benjamin L Parker, Beverley A Murrow, Jacqueline Stöckli, Christopher C Meoli, Geoffrey D Holman, David E James

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

Insulin signalling augments glucose transport by regulating glucose transporter 4 (GLUT4) trafficking from specialised intracellular compartments, termed GLUT4 storage vesicles (GSVs), to the plasma membrane (PM). Proteomic analysis of GSVs by mass spectrometry (MS) revealed enrichment of 59 proteins in these vesicles. We measured reduced abundance of 23 of these proteins following insulin stimulation and assigned these as high confidence GSV proteins. These included established GSV proteins such as GLUT4 and IRAP, as well as 6 proteins not previously reported to be localised to GSVs. Tumour suppressor candidate 5 (TUSC5) was shown to be a novel GSV protein that underwent a 3.7 fold increase in abundance at the PM in response to insulin. SiRNA mediated knockdown of TUSC5 decreased insulin-stimulated glucose uptake, while overexpression of TUSC5 had the opposite effect, implicating TUSC5 as a positive regulator of insulin-stimulated glucose transport in adipocytes. Incubation of adipocytes with TNFα caused insulin resistance and a concomitant reduction in TUSC5. Consistent with previous studies, PPARγ agonism reversed TNFα-induced insulin resistance. TUSC5 expression was necessary but insufficient for PPARγ mediated reversal of insulin resistance. These findings functionally link TUSC5 to GLUT4 trafficking, insulin action, insulin resistance and PPARγ action in the adipocyte. Further studies are required to establish the exact role of TUSC5 in adipocytes.

Original languageEnglish
Pages (from-to)23528-23542
Number of pages15
JournalThe Journal of biological chemistry
Volume290
Issue number39
Early online date3 Aug 2015
DOIs
Publication statusPublished - 25 Sep 2015

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