We are interested understanding how insulin stimulates glucose transport into fat and muscle cells, and how this process breaks down in disease.
One of the ways in which insulin lowers blood glucose is through stimulating glucose transport into adipose and muscle tissue. Insulin activates a signal transduction cascade in these tissues to promote the translocation of the glucose transporter GLUT4 from specialised intracellular storage vesicles to the plasma membrane, facilitating glucose uptake. We currently have an incomplete understanding of the signalling events and trafficking processes that control the redistribution of GLUT4. One of the objectives of our work is to fill in these knowledge gaps.
The reason we want to increase our understanding in this area is that impaired insulin-stimulated glucose transport in muscle and fat is a major contributor to whole body insulin resistance – a state where insulin no longer efficiently lowers blood glucose and a risk factor for type II diabetes. There is currently no consensus on the molecular basis for impaired insulin responses in these tissues. We aim to shed light on how the insulin signalling network and GLUT4 trafficking apparatus are altered in insulin resistance.
We take an interdisciplinary approach using cell culture and in vivo models to study insulin action, GLUT4 trafficking and glucose metabolism. We design and perform unbiased mass spectrometry-based proteomics studies to uncover proteins or protein post-translational modifications (e.g. phosphorylation) that may play a role in insulin-stimulated GLUT4 trafficking and/or insulin resistance.
A current focus of our work is to develop techniques that allow us to screen many genes-of-interest for a role in insulin-stimulated GLUT4 trafficking, and that allow us to study district aspects of GLUT4 trafficking in cells (e.g. delivery to the cell surface, internalisation). We use our expertise in cell biology (e.g. microscopy) and biochemistry (e.g. subcellular fractionation, immunoprecipitation) techniques to study the role that proteins-of-interest play in the insulin signalling-GLUT4 pathway in health and disease.
- Duan X, Norris DM, Humphrey SJ, Yang P, Cooke KC, Bultitude WP, Parker BL, Conway OJ, Burchfield JG, Krycer JR, Brodsky FM, James DE, Fazakerley DJ. Trafficking regulator of GLUT4-1 (TRARG1) is a GSK3 substrate. Biochem J. 2022 479(11):1237-1256.
- Calejman CM, Doxsey WG, Fazakerley DJ, Guertin DA. Integrating adipocyte insulin signaling and metabolism in the multi-omics era. Trends Biochem Sci. 2022 47(6):531-546.
- Fazakerley DJ, Koumanov F, Holman GD. GLUT4 On the move. Biochem J. 2022 479(3):445-462.
- Ayer A, Fazakerley DJ, Suarna C, Maghzal GJ, Sheipouri D, Lee KJ, Bradley MC, Fernández-Del-Rio L, Tumanov S, Kong SM, van der Veen JN, Yang A, Ho JWK, Clarke SG, James DE, Dawes IW, Vance DE, Clarke CF, Jacobs RL, Stocker R. Genetic screening reveals phospholipid metabolism as a key regulator of the biosynthesis of the redox-active lipid coenzyme Q. Redox Biol. 2021 46:102127.
- Krycer JR, Elkington SD, Diaz-Vegas A, Cooke KC, Burchfield JG, Fisher-Wellman KH, Cooney GJ, Fazakerley DJ, James DE#. Mitochondrial oxidants, but not respiration, are sensitive to glucose in adipocytes. J Biol Chem. 2020 295(1):99-110.
- Kearney AL, Cooke KC, Norris DM, Zadoorian A, Krycer JR, Fazakerley DJ, Burchfield JG, James DE. Serine 474 phosphorylation is essential for maximal Akt2 kinase activity in adipocytes. J Biol Chem. 2019 294(45):16729-16739.
- Fazakerley DJ*, Fritzen AM*, Nelson ME, Thorius IH, Cooke KC., Humphrey SJ, Cooney GJ and James DE. Insulin Tolerance Test under Anaesthesia to Measure Tissue-specific Insulin-stimulated Glucose Disposal. Bio-protocol. 2019 9(2): e3146.
- Duan X, Krycer JR#, Cooke KC, Yang G, James DE#, Fazakerley DJ. Membrane Topology of Trafficking Regulator of GLUT4 1 (TRARG1). Biochemistry. 2018, 57(26):3606-3615.
- Fazakerley DJ*, Minard AY*, Krycer JR, Thomas KC, Stöckli J, Harney DJ, Burchfield JG, Maghzal GJ, Caldwell ST, Hartley RC, Stocker R, Murphy MP, James DE. Mitochondrial oxidative stress causes insulin resistance without disrupting oxidative Phosphorylation. J Biol Chem. 2018 293(19):7315-7328.
- Fazakerley DJ, Chaudhuri R, Yang P, Maghzal GJ, Thomas KC, Krycer JR, Humphrey SJ, Parker BL, Fisher-Wellman KH, Meoli1 CC, Hoffman NJ, Diskin C, Burchfield JG, Cowley MJ, Kaplan WH, Modrusan Z, Kolumam G, Yang JYH, Chen DL, Samocha-Bonet D, Greenfield JR, Hoehn KL, Stocker R, James DE. Mitochondrial CoQ deficiency is a common driver of mitochondrial oxidants and insulin resistance. Elife. 2018 6;7.