Diabetes

 Prostaglandin F2{alpha} Facilitates Hepatic Glucose Production Through CaMKII{gamma}/p38/FOXO1 Signaling Pathway in Fasting and Obesity
 

Gluconeogenesis is drastically increased in patients with type 2 diabetes and accounts for increased fasting plasma glucose concentrations. Circulating levels of prostaglandin (PG) F are also markedly elevated in diabetes; however, whether and how PGF regulates hepatic glucose metabolism remain unknown. Here, we demonstrated that PGF receptor (F-prostanoid receptor [FP]) was upregulated in the livers of mice upon fasting- and diabetic stress. Hepatic deletion of the FP receptor suppressed fasting-induced hepatic gluconeogenesis, whereas FP overexpression enhanced hepatic gluconeogenesis in mice. FP activation promoted the expression of gluconeogenic enzymes (PEPCK and glucose-6-phosphatase) in hepatocytes in a FOXO1-dependent manner. Additionally, FP coupled with Gq in hepatocytes to elicit Ca2+ release, which activated Ca2+/calmodulin-activated protein kinase II (CaMKII) to increase FOXO1 phosphorylation and subsequently accelerate its nuclear translocation. Blockage of p38 disrupted CaMKII-induced FOXO1 nuclear translocation and abrogated FP-mediated hepatic gluconeogenesis in mice. Moreover, knockdown of hepatic FP receptor improved insulin sensitivity and glucose homeostasis in ob/ob mice. FP-mediated hepatic gluconeogenesis via the CaMKII/p38/FOXO1 signaling pathway, indicating that the FP receptor might be a promising therapeutic target for type 2 diabetes.