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GLUT4 traffic through an ESCRT-III-dependent sorting compartment in adipocytes
Françoise Koumanov1, Vinit J Pereira, Paul R Whitley
1Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom. f.koumanov@bath.ac.uk
Plos One
|October 11, 2012
Summary
The ESCRT machinery is crucial for sorting glucose transporter type 4 (GLUT4) into specialized storage compartments in cells. Impairing ESCRT function disrupts GLUT4 trafficking, hindering insulin
Area of Science:
- Cell Biology
- Molecular Biology
- Endocrinology
Background:
- Glucose transporter type 4 (GLUT4) is essential for insulin-stimulated glucose uptake.
- GLUT4 trafficking involves complex sorting mechanisms potentially regulated by ubiquitination and SUMOylation.
- Endosomal Sorting Complexes Required for Transport (ESCRT) machinery influences cellular sorting processes.
Purpose of the Study:
- To investigate the role of ESCRT components in GLUT4 trafficking.
- To determine if GLUT4 traffic is routed through ESCRT-dependent sorting steps.
- To elucidate the impact of ESCRT inhibition on GLUT4 localization and insulin responsiveness.
Main Methods:
- Expression of dominant-negative ESCRT-III (CHMP3(1-179)) and Vps4 (GFP-Vps4(E235Q)) inhibitory constructs in rat adipocytes.
- Immunofluorescence microscopy to assess co-localization of GLUT4 with ESCRT constructs and cellular markers.
- Analysis of GLUT4 localization in response to insulin signaling.
Main Results:
- Inhibition of ESCRT components led to the accumulation of GLUT4 in large, coalesced vesicles.
- GLUT4 co-localized extensively with endosomal markers (EEA1, transferrin receptor) and TGN marker (syntaxin6) in perturbed cells.
- ESCRT inhibition resulted in impaired insulin-stimulated GLUT4 translocation to the cell surface.
Conclusions:
- ESCRT-dependent sorting is critical for routing GLUT4 to its specialized storage reservoir.
- Dysfunction of the ESCRT pathway disrupts GLUT4 trafficking and insulin sensitivity.
- These findings highlight a novel role for ESCRT in regulating glucose homeostasis.
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