de Souza, Arnaldo HenriqueTang, JiayinYadev, Amanjot KaurSaghafi, Samuel T.Kibbe, Carly R.Linnemann, Amelia K.Merrins, Matthew J.Davis, Dawn2020-04-062020-04-062020-02-18de Souza, A. H., Tang, J., Yadev, A. K., Saghafi, S. T., Kibbe, C. R., Linnemann, A. K., Merrins, M. J., & Davis, D. B. (2020). Intra-islet GLP-1, but not CCK, is necessary for β-cell function in mouse and human islets. Scientific reports, 10(1), 2823. https://doi.org/10.1038/s41598-020-59799-2https://hdl.handle.net/1805/22481Glucagon-like peptide 1 (GLP-1) and cholecystokinin (CCK) are gut-derived peptide hormones known to play important roles in the regulation of gastrointestinal motility and secretion, appetite, and food intake. We have previously demonstrated that both GLP-1 and CCK are produced in the endocrine pancreas of obese mice. Interestingly, while GLP-1 is well known to stimulate insulin secretion by the pancreatic β-cells, direct evidence of CCK promoting insulin release in human islets remains to be determined. Here, we tested whether islet-derived GLP-1 or CCK is necessary for the full stimulation of insulin secretion. We confirm that mouse pancreatic islets secrete GLP-1 and CCK, but only GLP-1 acts locally within the islet to promote insulin release ex vivo. GLP-1 is exclusively produced in approximately 50% of α-cells in lean mouse islets and 70% of α-cells in human islets, suggesting a paracrine α to β-cell signaling through the β-cell GLP-1 receptor. Additionally, we provide evidence that islet CCK expression is regulated by glucose, but its receptor signaling is not required during glucose-stimulated insulin secretion (GSIS). We also see no increase in GSIS in response to CCK peptides. Importantly, all these findings were confirmed in islets from non-diabetic human donors. In summary, our data suggest no direct role for CCK in stimulating insulin secretion and highlight the critical role of intra-islet GLP-1 signaling in the regulation of human β-cell function.en-USAttribution 4.0 InternationalHomeostasisDiabetesObesityArticle