GPR119 expression in normal human tissues and islet cell tumors: evidence for its islet-gastrointestinal distribution, expression in pancreatic beta and alpha cells, and involvement in islet function.

Abstract

[Objective]GPR119 is reportedly involved in regulating glucose metabolism and food intake in rodents, but little is known about its expression and functional significance in humans. To begin to assess the potential clinical importance of GPR119, the distribution of GPR119 gene expression in humans was examined. [Materials/Methods]Expression of GPR119 mRNA in fresh samples of normal human pancreas (n = 19) and pancreatic islets (n = 3) and in insulinomas (n = 2) and glucagonomas (n = 2), all collected at surgery, was compared with the mRNA expression of various receptors highly expressed and operative in human pancreatic islets. [Results]GPR119 mRNA was most abundant in the pancreas, followed by the duodenum, stomach, jejunum, ileum and colon. Pancreatic levels of GPR119 mRNA were similar to those of GPR40 mRNA and were higher than those of GLP1R and SUR1 mRNA, which are strongly expressed in human pancreatic islets. Moreover, levels of GPR119 mRNA in pancreatic islets were more than 10 times higher than in adjacent pancreatic tissue, as were levels of GPR40 mRNA. GPR119 mRNA was also abundant in two cases of insulinoma and two cases of glucagonoma, but was undetectable in a pancreatic acinar cell tumor. Similar results were obtained with mouse pancreatic islets, MIN6 insulinoma cells and alpha-TC glucagonoma cells. [Conclusions]The results provide evidence of an islet-gastrointestinal distribution of GPR119, its expression in pancreatic beta and alpha cells, and its possible involvement in islet function. They also provide the basis for a better understanding of the potential clinical importance of GPR119.