Diabetic and ER-stressed pancreatic islet β cells are in need of some JNK removal

Pancreatic β cells regulate glucose homeostasis through insulin secretion, but nutrient overload and genetic defects can trigger ER stress and apoptosis, contributing to type 2 diabetes. Within β cells, the kinases PERK, IRE1α, and ATF6 initiate the unfolded protein response (UPR) as a result of ER stress, a process that is constitutively suppressed under nonstress conditions by GRP78 binding to these proteins. To gain insight into the mechanisms of β cell death upon dysregulated ER stress, Sharma et al. used β cell–specific GRP78 knockout models, revealing that hyperactivation of the UPR promoted β cell death primarily through the IRE1α/JNK/p53 signaling pathway. Pharmacological inhibition of JNK improved β cell survival, increased insulin levels, and lowered blood glucose in multiple diabetic mouse models. These findings highlight JNK signaling as a promising therapeutic target for preserving β cell function.