Circadian clocks drive regeneration of pancreatic β-cells in mice

We aimed to understand the functional roles of islet cellular oscillators under diabetic conditions and during β-cell regeneration. We assessed diurnal regulation of β-cell proliferation and the transcriptional landscape in α- and residual β-cells following β-cell ablation in Insulin-rtTA/TET-DTA mice that simultaneously expressed α- and β-cell specific fluorescent reports. The mouse pancreatic islets were isolated over 24-h with 4-h interval, followed by separation of α- and β- cells using FACS sorting, RNA extraction and RNA sequencing. Acute hyperglycemia and loss of β-cell mass perturbed absolute expression levels and temporal transcriptome profiles in residual β-cells, whereas in neighboring α-cells only changes in temporal profiles were observed. Strikingly, compensatory regeneration of β-cells exhibited circadian rhythmicity. In arrhythmic Bmal1 deficient mice, massive β-cell ablation led to aggravated hyperglycemia, hyperglucagonemia and a fatal diabetes. No compensatory proliferation of β-cells was observed in arrhythmic mice, suggesting an essential role of circadian clocks in β-cell regeneration.