GLUT4 traffic through an ESCRT-III-dependent sorting compartment in adipocytes.
In insulin target tissues, GLUT4 is known to traffic through multiple compartments that may involve ubiquitin- and/or SUMO-dependent targeting. During these trafficking steps, GLUT4 is sorted into a storage reservoir compartment that is acutely released by insulin signalling processes that are downstream of PI 3-kinase associated changes in inositol phospholipids. As ESCRT components have recently been found to influence cellular sorting processes that are related to changes in both ubiquitination and inositol phospholipids, we have examined whether GLUT4 traffic is routed through ESCRT dependent sorting steps. Introduction of the dominant negative inhibitory constructs of the ESCRT-III components CHMP3 (CHMP3(1-179)) and Vps4 (GFP-Vps4(E235Q)) into rat adipocytes leads to the accumulation of GLUT4 in large, coalesced and extended vesicles structures that co-localise with the inhibitory constructs over large parts of the extended structure. A new swollen hybrid and extensively ubiquitinated compartment is produced in which GLUT4 co-localises more extensively with the endosomal markers including EEA1 and transferrin receptors but also with the TGN marker syntaxin6. These perturbations are associated with failure of insulin action on GLUT4 traffic to the cell surface and suggest impairment in an ESCRT-dependent sorting step used for GLUT4 traffic to its specialised reservoir compartment.
Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom. f.koumanov@bath.ac.uk
Françoise
F
Koumanov
Vinit J
VJ
Pereira
Paul R
PR
Whitley
Geoffrey D
GD
Holman
D017667:Adipocytes / Q000166:cytology / Q000378:metabolism*; D000818:Animals; D018274:Electroporation; D056827:Endosomal Sorting Complexes Required for Transport / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D051275:Glucose Transporter Type 4 / Q000235:genetics / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism; D010957:Plasmids; D061251:Primary Cell Culture; D021381:Protein Transport; D050765:Qa-SNARE Proteins / Q000235:genetics / Q000378:metabolism; D051381:Rats; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014162:Transfection; D025801:Ubiquitin / Q000235:genetics / Q000378:metabolism; D054875:Ubiquitination; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism; D021601:trans-Golgi Network / Q000235:genetics / Q000378:metabolism*
D056827:Endosomal Sorting Complexes Required for Transport; D051275:Glucose Transporter Type 4; D007328:Insulin; D019869:Phosphatidylinositol 3-Kinases; D010716:Phosphatidylinositols; D050765:Qa-SNARE Proteins; D029701:Saccharomyces cerevisiae Proteins; D025801:Ubiquitin; D033921:Vesicular Transport Proteins; C495694:Slc2a4 protein, rat; C093846:early endosome antigen 1