Pancreatic Alpha Cells and Glucagon Secretion in Mouse Models of Diabetes (360G-Wellcome-109115_Z_15_A)

Type 2 diabetes (T2DM) is characterised by insufficient insulin secretion, insulin resistance and dysregulated glucagon secretion. The processes underlying alpha-cell dysfunction in T2DM, leading to elevated glucagon secretion and exacerbated hyperglycaemia, remain poorly understood. With evidence indicating that electrical activity, Ca2+ signalling and hormone secretion occur somewhat independently of each other (at different times, under different conditions), the nature of alpha-cell signal transduction is unclear. We will generate mice expressing the Ca2+ sensitive fluorescent indicator (GCaMP) under the glucagon promoter and will measure Ca2+ oscillations in isolated islets alongside electrical activity. Following fluorescence activated cell sorting (FACS) of whole islets, electrical activity and Ca2+ signalling of isolated alpha-cells will be performed to assess the impact of loss of paracrine effects on alpha-cell function. mRNA and protein expression will also be measured in isolated cells to verify the specificity of marker expression. Also all experiments will be conducted in diabetic mice and littermate controls to assess the effect of hyperglycaemia and beta-cell dysfunction on alpha-cell physiology. These studies, conclusively characterising the nature of stimulus secretion coupling in pancreatic alpha-cells, and its disintegration in T2D, will provide valuable insight into the process underlying pancreatic dysfunction and possible opportunities to reclaim glycaemic control.