Beta‐Cell Tipe1 Orchestrates Insulin Secretion and Cell Proliferation by Promoting Gαs/cAMP Signaling via USP5

Abstract

Inadequate β‐cell mass and insulin secretion are essential for the development of type 2 diabetes (T2D). TNF‐α‐induced protein 8‐like 1 (Tipe1) plays a crucial role in multiple diseases, however, a specific role in T2D pathogenesis remains largely unexplored. Herein, Tipe1 as a key regulator in T2D, contributing to the maintenance of β cell homeostasis is identified. The results show that the β‐cell‐specific knockout of Tipe1 (termed Ins2‐Tipe1BKO) aggravated diabetic phenotypes in db/db mice or in mice with high‐fat diet‐induced diabetes. Notably, Tipe1 improves β cell mass and function, a process that depends on Gαs, the α subunit of the G‐stimulating protein. Mechanistically, Tipe1 inhibited the K48‐linked ubiquitination degradation of Gαs by recruiting the deubiquitinase USP5. Consequently, Gαs or cAMP agonists almost completely restored the dysfunction of β cells observed in Ins2‐Tipe1BKO mice. The findings characterize Tipe1 as a regulator of β cell function through the Gαs/cAMP pathway, suggesting that Tipe1 may emerge as a novel target for T2D intervention.