Black, H. L. et al. (2022) Knockout of Syntaxin-4 in 3T3-L1 adipocytes reveals new insight into GLUT4 trafficking and adiponectin secretion. Journal of Cell Science, 135(1), jcs258375. (doi: 10.1242/jcs.258375) (PMID:34859814) (PMCID:PMC8767277)
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Abstract
Adipocytes are key to metabolic regulation, exhibiting insulin-stimulated glucose transport which is underpinned by the insulin-stimulated delivery of glucose transporter-4 (GLUT4)- containing vesicles to the plasma membrane where they dock and fuse increasing cell surface GLUT4 levels. Adipocytokines such as adiponectin are secreted via a similar mechanism. We used genome editing to knockout Syntaxin-4 a protein reported to mediate GLUT4-vesicle fusion with the plasma membrane in 3T3-L1 adipocytes. Syntaxin-4 knockout reduced insulin-stimulated glucose transport and adiponectin secretion by ∼50% and reduced GLUT4 levels. Ectopic expression of HA-GLUT4-GFP showed that Syntaxin-4 knockout cells retain significant GLUT4 translocation capacity demonstrating that Syntaxin-4 is dispensable for insulin-stimulated GLUT4 translocation. Analysis of recycling kinetics revealed only a modest reduction in the exocytic rate of GLUT4 in knockout cells, and little effect on endocytosis. These analyses demonstrate that Syntaxin-4 is not always rate limiting for GLUT4 delivery to the cell surface. In sum, we show that Syntaxin-4 knockout results in reduced insulin-stimulated glucose transport, depletion of cellular GLUT4 levels and inhibition of adiponectin secretion but has only modest effects on the translocation capacity of the cells.
| Item Type: | Articles |
|---|---|
| Additional Information: | This work was supported by grants from Diabetes UK (15/0005246, 17/0005605, 17/0005724,18/0005847, 18/0005905 and 19/0005978 to GWG and/or NJB), the Novo Nordisk Research Foundation (to GWG, JRP and JGB). AG thanks the Lister Institute for a summer research stipend and the EPSRC for a PhD studentship (AG). Mal-T thanks the Government of Oman for a studentship. CCM thanks the University of Nevada, Reno for sabbatical support. |
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Boyle, Dr James and Gould, Professor Gwyn and Livingstone, Dr Rachel and AL TOBI, Mohammed Nasser Rashid and Kioumourtzoglou, Mr Dimitrios and Petrie, Professor John and Stirrat, Mrs Laura |
| Authors: | Black, H. L., Livingstone, R., Mastick, C. C., Al Tobi, M., Taylor, H., Geiser, A., Stirrat, L., Kioumourtzoglou, D., Petrie, J. R., Boyle, J. G., Bryant, N. J., and Gould, G. W. |
| College/School: | College of Medical Veterinary and Life Sciences > School of Cardiovascular & Metabolic Health College of Medical Veterinary and Life Sciences > School of Molecular Biosciences College of Medical Veterinary and Life Sciences > School of Medicine, Dentistry & Nursing |
| Journal Name: | Journal of Cell Science |
| Publisher: | Company of Biologists |
| ISSN: | 0021-9533 |
| ISSN (Online): | 1477-9137 |
| Published Online: | 03 December 2021 |
| Copyright Holders: | Copyright © 2021 The Company of Biologists Ltd |
| First Published: | First published in Journal of Cell Science 135(1): jcs258375 |
| Publisher Policy: | Reproduced under a Creative Commons License |
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