mouse strain FVB/NJ-Tg(MIP-Luc-VU)3Pwrs/J mouse strain A mouse strain containing a transgene in which Luc (transgene) is driven by the MIP promoter (NCBI Gene ID: 16333). We generated a transgenic mouse expressing the luciferase optical reporter under control of the mouse insulin I promoter (MIP-Luc-VU) and characterized this model in mice with increased or decreased beta-cell mass and after islet transplantation. MIP-Luc-VU mice emitted strong and consistent bioluminescence emanating exclusively from beta-cells of the pancreatic islet. MIP-Luc-VU islets had normal islet architecture and secreted insulin normally in vivo and in vitro. By tracking changes in β cell mass using bioluminescence imaging (BLI) and post-mortem metrics, streptozotocin-induced, diabetic MIP-Luc-VU mice had a progressive decline in bioluminescence that correlated with a decrease in pancreatic insulin content and beta-cell mass. MIP-Luc-VU animals fed a high fat diet displayed a progressive increase in bioluminescence that reflected an immunohistochemically verified increase in beta-cell mass. MIP-Luc-VU islets transplanted beneath the renal capsule or into the liver emitted bioluminescence proportional to the number of islets transplanted and graft insulin content and could be imaged for more than a year. Since bioluminescence in the MIP-Luc-VU mouse model is proportional to beta-cell mass in the setting of increased and decreased beta-cell mass and after transplantation, this approach should be useful for non-invasively assessing beta-cell mass in pre-clinical mouse models of glucose homeostasis, beta-cell growth and regeneration, and diabetes. FVB/NJ-Tg(MIP-Luc-VU)3Pwrs/J Person: Mark A. Magnuson, Jill Lindner, Jean-Philippe Cartailler Vanderbilt University Medical Center