Transgenic mice with green fluorescent protein-labeled pancreatic beta -cells

1 Department of Medicine, 2 The Howard Hughes Medical Institute, 3 Departments of Pathology, 4 Neurobiology, Pharmacology and Physiology, and 5 Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois 60637; and 6 Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee 37232 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 coexpression of insulin and GFP in the -cells of all islets. We observed GFP expression in islets from embryonic day E13.5 through adulthood. Studies of -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 -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-wk-old mice were -cells. The MIP-GFP-transgenic mouse may be a useful tool for studying -cell biology in normal and diabetic animals. insulin; diabetes