Gi-GPCRs, G protein-coupled receptors that signal via Gα proteins of the i/o class (Gαi/o), acutely regulate cellular behaviors widely in mammalian tissues, but their impact on the development and growth of these tissues is less clear. For example, Gi-GPCRs acutely regulate insulin release from pancreatic cells, and variants in genes encoding several Gi-GPCRs
—including the α-2a adrenergic receptor, ADRA2A—increase the risk of type 2 diabetes mellitus.
However, type 2 diabetes also is associated with reduced total β-cell mass, and the role of Gi-GPCRs in establishing
β-cell mass is unknown. Therefore, we asked whether Gi-GPCR signaling regulates β-cell mass. Here we show that Gi-GPCRs limit the proliferation of the insulin-producing pancreatic β cells and especially their expansion during the critical perinatal period.
Increased Gi-GPCR activity in peri-natal β cells decreased β-cell proliferation, reduced adult β-cell mass,
and impaired glucose homeostasis. In contrast, Gi-GPCR inhibition enhanced perinatal β-cell proliferation, increased adult
β-cell mass,and improved glucose homeostasis. Transcriptome analysis detected the expression of multiple Gi
-GPCRs in developing and adult β cells,and gene-deletion experiments identified ADRA2A as a key Gi-GPCR regulator of
β-cell replication. These studies link Gi-GPCR signaling to β-cell mass and diabetes risk and identify it as a poten-
tial target for therapies to protect and increase β -cell mass in patients with diabetes.