Proteomics analysis for the study of beta cell adaptation to stress in mice deficient for insulin-degrading enzyme (IDE)

Appropriate tuning of protein homeostasis through mobilization of the unfolded protein response (UPR) is key to the capacity of pancreatic beta cells to cope with highly variable demand for insulin synthesis. An efficient UPR ensures a sufficient beta cell mass and secretory output but can also affect beta cell resilience to autoimmune aggression. However, the factors regulating protein homeostasis in the face of metabolic and immune challenges are insufficie tly understood. We examined beta cell adaptation to stress in mice deficient for insulin-degrading enzyme (IDE), a ubiquitous protease with high affinity for insulin, a putative ill-defined role in protein homeostasis, and genetic association with type 2 diabetes. IDE deficiency induces a low-level UPR in both standard and autoimmune non-obese diabetic (NOD) mice, associated with rapamycin-sensitive beta cell proliferation, as well as protection from diabetes in NOD mice. Moreover, in NOD islets, IDE deficiency specifically induces strong upregulation of regenerating islet-derived protein 2, a protein attenuating inflammation and protecting from autoimmunity. Our findings establish a role of IDE in islet cell protein homeostasis, corroborate the link between low-level UPR and proliferation, and identify an anti-inflammatory islet cell response uncovered in the absence of IDE of potential interest in autoimmune diabetes.