Generation and Characterization of a Novel Mouse Model That Allows Spatiotemporal Quantification of Pancreatic β-Cell...

Pancreatic β-cell proliferation has been gaining much attention as a therapeutic target for the prevention and treatment of diabetes. In order to evaluate potential β-cell mitogens, accurate and reliable methods for the detection and quantification of the β-cell proliferation rate are indispensable. In this study, we developed a novel tool that specifically labels replicating β-cells as mVenus⁺ cells by using RIP-Cre; R26Fucci2aR mice expressing the fluorescent ubiquitination-based cell cycle indicator Fucci2a in β-cells. In response to β-cell proliferation stimuli, such as insulin receptor antagonist S961 and diet-induced obesity (DIO), the number of 5-ethynyl-2'-deoxyuridine-positive insulin⁺ cells per insulin⁺ cells and the number of mVenus⁺ cells per mCherry⁺ mVenus^- cells + mCherry^- mVenus⁺ cells were similarly increased in these mice. Three-dimensional imaging of optically cleared pancreas tissue from these mice enabled quantification of replicating β-cells in the islets and morphometric analysis of the islets after known mitogenic interventions such as S961, DIO, pregnancy, and partial pancreatectomy. Thus, this novel mouse line is a powerful tool for spatiotemporal analysis and quantification of β-cell proliferation in response to mitogenic stimulation.