GLP-1 is a potent glucose-dependent insulinotropic hormone derived from intestinal L cells. Inflammatory Interleukin-27 (IL-27), a pleiotropic two-chain cytokine, is composed of EBI3 and IL-27 p28 subunits. IL-27 has a protective effect on pancreatic β-cell function. The relationship between IL-27 and GLP-1 is still unexplored. Here we showed interleukin-27-stimulated GLP-1 production via the Stat3-mTOR-dependent mechanism. Interleukin 27 receptor subunit alpha (IL-27 Rα) was detected in ileum and STC-1 cells. Co-localization of EBI3 and GLP-1 was observed not only in mouse ileums but also in human ileums and colons. Third-ventricular infusion of IL-27 increased ileal and plasma GLP-1 in both lean C57BL/6J mice and diet-induced obese and diabetic mice. These changes were associated with a significant increase in Stat3-mTOR activity. Treatment of STC-1 cells with IL-27 contributed to the increments of Stat3-mTOR signaling and GLP-1. Interference of mTOR activity by mTOR siRNA or rapamycin abolished the stimulation of GLP-1 production induced by IL-27 in STC-1 cells. Stat3 siRNA also blocked the stimulus effect of IL-27 on GLP-1. IL-27 increased the interaction of mTOR and Stat3 in STC-1 cells. Our results identify Stat3-mTOR as a critical signaling pathway for the stimulation of GLP-1 induced by IL-27.
Keywords: GLP-1; Stat3; interleukin-27; mTOR.