Pleiotropic effects of Syntaxin16 identified by gene editing in cultured adipocytes

Bremner, S. K. , Al Shammari, W. O., Milligan, R. S., Hudson, B. D. , Sutherland, C., Bryant, N. J. and Gould, G. W. (2022) Pleiotropic effects of Syntaxin16 identified by gene editing in cultured adipocytes. Frontiers in Cell and Developmental Biology, 10, 1033501. (doi: 10.3389/fcell.2022.1033501) (PMID:36467416) (PMCID:PMC9716095)

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Abstract

Adipocytes play multiple roles in the regulation of glucose metabolism which rely on the regulation of membrane traffic. These include secretion of adipokines and serving as an energy store. Central to their energy storing function is the ability to increase glucose uptake in response to insulin, mediated through translocation of the facilitative glucose transporter GLUT4 to the cell surface. The trans-Golgi reticulum localized SNARE protein syntaxin 16 (Sx16) has been identified as a key component of the secretory pathway required for insulin-regulated trafficking of GLUT4. We used CRISPR/Cas9 technology to generate 3T3-L1 adipocytes lacking Sx16 to understand the role of the secretory pathway on adipocyte function. GLUT4 mRNA and protein levels were reduced in Sx16 knockout adipocytes and insulin stimulated GLUT4 translocation to the cell surface was reduced. Strikingly, neither basal nor insulin-stimulated glucose transport were affected. By contrast, GLUT1 levels were upregulated in Sx16 knockout cells. Levels of sortilin and insulin regulated aminopeptidase were also increased in Sx16 knockout adipocytes which may indicate an upregulation of an alternative GLUT4 sorting pathway as a compensatory mechanism for the loss of Sx16. In response to chronic insulin stimulation, Sx16 knockout adipocytes exhibit elevated insulin-independent glucose transport and significant alterations in lactate metabolism. We further show that the adipokine secretory pathways are impaired in Sx16 knockout cells. Together this demonstrates a role for Sx16 in the control of glucose transport, the response to elevated insulin, cellular metabolic profiles and adipocytokine secretion.

Item Type:Articles
Additional Information:Funding: Diabetes United Kingdom–grant 18/0005847 (to GG, CS and NB) and 20/0006218 (to GG and CS) and research scholarships from the University of Hafr Al Batin to WA.
Keywords:Syntaxin 16 (STX16), GLUT4, adipocyte, adipokine, CRISPR.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Bremner-Hart, Dr Shaun and Gould, Professor Gwyn and Al Shammari, Woroud Sayel O and Bryant, Dr Nia and Hudson, Dr Brian
Authors: Bremner, S. K., Al Shammari, W. O., Milligan, R. S., Hudson, B. D., Sutherland, C., Bryant, N. J., and Gould, G. W.
College/School:College of Medical Veterinary and Life Sciences > School of Molecular Biosciences
Journal Name:Frontiers in Cell and Developmental Biology
Publisher:Frontiers Media
ISSN:2296-634X
ISSN (Online):2296-634X
Copyright Holders:Copyright © 2022 Bremner, Al Shammari, Milligan, Hudson, Sutherland, Bryant and Gould
First Published:First published in Frontiers in Cell and Developmental Biology 10: 1033501
Publisher Policy:Reproduced under a Creative Commons License

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