Transgenic Mice with Green Fluorescent Protein-labeled Pancreatic -cells

We have generated transgenic mice that express green fluorescent protein (GFP) under the control of the mouse insulin I gene promoter (MIP). The MIP-GFP mice develop normally and are indistinguishable from control animals with respect to glucose tolerance and pancreatic insulin content. Histological studies showed that the MIP-GFP mice had normal islet architecture with co-expression of insulin and GFP in the β-cells of all islets. We observed GFP expression in islets from embryonic E13.5 day through adult. Studies of β-cell function revealed no difference in glucose-induced intracellular calcium mobilization between islets from transgenic and control animals. We prepared single-cell suspensions from both isolated islets and whole pancreas from MIP-GFP transgenic mice and sorted the β-cells by fluorescence-activated cell sorting based on their green fluorescence. These studies showed that 2.4±0.2% (n=6) of the cells in the pancreas of newborn (P1) and 0.9±0.1% (n=5) of 8-week old mice were β-cells. The MIP-GFP transgenic mice may be a useful tool for studying β-cell biology in normal and diabetic animals. Key word: insulin, diabetes, GFP, transgenic, β-cell