Beta cell-specific Znt8 deletion in mice causes marked defects in insulin processing, crystallisation and secretion
- N. WijesekaraAffiliated withDepartment of Physiology, University of Toronto
- , F. F. DaiAffiliated withDepartment of Physiology, University of Toronto
- , A. B. HardyAffiliated withDepartment of Physiology, University of Toronto
- , P. R. GiglouAffiliated withDepartment of Physiology, University of Toronto
- , A. BhattacharjeeAffiliated withDepartment of Physiology, University of Toronto
- , V. KoshkinAffiliated withDepartment of Physiology, University of Toronto
- , F. ChimientiAffiliated withMellitech
- , H. Y. GaisanoAffiliated withDepartment of Medicine, University of Toronto
- , G. A. RutterAffiliated withSection of Cell Biology, Division of Medicine, Imperial College London
- and 1 more
Zinc is highly concentrated in pancreatic beta cells, is critical for normal insulin storage and may regulate glucagon secretion from alpha cells. Zinc transport family member 8 (ZnT8) is a zinc efflux transporter that is highly abundant in beta cells. Polymorphisms of ZnT8 (also known as SLC30A8) gene in man are associated with increased risk of type 2 diabetes. While global Znt8 knockout (Znt8KO) mice have been characterised, ZnT8 is also present in other islet cell types and extra-pancreatic tissues. Therefore, it is important to find ways of understanding the role of ZnT8 in beta and alpha cells without the difficulties caused by the confounding effects of ZnT8 in these other tissues.
We generated mice with beta cell-specific (Znt8BKO) and alpha cell-specific (Znt8AKO) knockout of Znt8, and performed in vivo and in vitro characterisation of the phenotypes to determine the functional and anatomical impact of ZnT8 in these cells. Thus we assessed zinc accumulation, insulin granule morphology, insulin biosynthesis and secretion, and glucose homeostasis.
Znt8BKO mice are glucose-intolerant, have reduced beta cell zinc accumulation and atypical insulin granules. They also display reduced first-phase glucose-stimulated insulin secretion, reduced insulin processing enzyme transcripts and increased proinsulin levels. In contrast, Znt8AKO mice show no evident abnormalities in plasma glucagon and glucose homeostasis.
This is the first report of specific beta and alpha cell deletion of Znt8. Our data indicate that while, under the conditions studied, ZnT8 is absolutely essential for proper beta cell function, it is largely dispensable for alpha cell function.
KeywordsAlpha cell Beta cell Glucagon Insulin Pancreatic islets SLC30A8 Zinc ZnT8
- Beta cell-specific Znt8 deletion in mice causes marked defects in insulin processing, crystallisation and secretion
Volume 53, Issue 8 , pp 1656-1668
- Cover Date
- Print ISSN
- Online ISSN
- Additional Links
- Alpha cell
- Beta cell
- Pancreatic islets
- Industry Sectors
- Author Affiliations
- 1. Department of Physiology, University of Toronto, 1 King’s College Circle Room 3352, Toronto, ON, Canada, M5S 1A8
- 3. Mellitech, Grenoble, France
- 2. Department of Medicine, University of Toronto, Toronto, ON, Canada
- 4. Section of Cell Biology, Division of Medicine, Imperial College London, London, UK