Decreased IGF1R Attenuates Senescence and Improves Function in Pancreatic beta-Cells
We previously reported that increased expression of IGF1R in mouse and human beta-cells is a marker of older beta-cells; however, its contribution to age-related dysfunction and cellular senescence remains to be determined. In this study, we explored the direct role of IGF1R in beta-cell function and senescence using inducible beta-cell specific IGF1R knockdown (betaIgf1rKD) mice. Adult betaIgf1rKD mice showed improved glucose clearance and glucose-induced insulin secretion, accompanied by decreased p21Cip1 protein expression in beta-cells. RNASeq of islets isolated from these betaIgf1rKD mice revealed restoration of 3 signaling pathways known to be downregulated by aging: sulfide oxidation, autophagy, and mTOR signaling. Additionally, deletion of IGF1R in mouse beta-cells increased transcription of genes important for maintaining beta-cell identity and function, such as Mafa, Nkx6.1, and Kcnj11, while decreasing senescence-related genes, such as Cdkn2a, Il1b, and Serpine 1. These results suggest that IGF1R signaling plays a causal role in aging-induced beta-cell dysfunction. Overall design: Islets isolated from 4 betaIgf1rKD and 4 betaIgf1r mice were resuspended in RNA extraction buffer and the RNeasy Micro Kit (No. 74004) was used to purify RNA and submitted for sequencing.