Glucagon-Like Peptide-1 Regulates Cholecystokinin Production in β-Cells to Protect From Apoptosis.

Linnemann AK, Neuman JC, Battiola TJ, Wisinski JA, Kimple ME, Davis DB
Mol Endocrinol. 2015 29 (7): 978-87

PMID: 25984632 · PMCID: PMC4484781 · DOI:10.1210/me.2015-1030

Cholecystokinin (CCK) is a classic gut hormone that is also expressed in the pancreatic islet, where it is highly up-regulated with obesity. Loss of CCK results in increased β-cell apoptosis in obese mice. Similarly, islet α-cells produce increased amounts of another gut peptide, glucagon-like peptide 1 (GLP-1), in response to cytokine and nutrient stimulation. GLP-1 also protects β-cells from apoptosis via cAMP-mediated mechanisms. Therefore, we hypothesized that the activation of islet-derived CCK and GLP-1 may be linked. We show here that both human and mouse islets secrete active GLP-1 as a function of body mass index/obesity. Furthermore, GLP-1 can rapidly stimulate β-cell CCK production and secretion through direct targeting by the cAMP-modulated transcription factor, cAMP response element binding protein (CREB). We find that cAMP-mediated signaling is required for Cck expression, but CCK regulation by cAMP does not require stimulatory levels of glucose or insulin secretion. We also show that CREB directly targets the Cck promoter in islets from obese (Leptin(ob/ob)) mice. Finally, we demonstrate that the ability of GLP-1 to protect β-cells from cytokine-induced apoptosis is partially dependent on CCK receptor signaling. Taken together, our work suggests that in obesity, active GLP-1 produced in the islet stimulates CCK production and secretion in a paracrine manner via cAMP and CREB. This intraislet incretin loop may be one mechanism whereby GLP-1 protects β-cells from apoptosis.

MeSH Terms (22)

Animals Apoptosis Base Sequence Body Mass Index Cell Line, Tumor Cholecystokinin Cyclic AMP Cyclic AMP Response Element-Binding Protein Cytoprotection Glucagon-Like Peptide 1 Humans Insulin Insulin-Secreting Cells Insulin Secretion Mice Molecular Sequence Data Obesity Phosphorylation Promoter Regions, Genetic Protein Binding Rats Receptors, Cholecystokinin

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