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Mechanistic insights into the detection of free fatty and bile acids by ileal glucagon-like peptide-1 secreting cells.

Published version
Peer-reviewed

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Authors

Goldspink, Deborah A 
Lu, Van B 
Billing, Lawrence J 
Tolhurst, Gwen 

Abstract

OBJECTIVES: The aim of this study was to investigate the electrical properties of ileal Glucagon-like peptide 1 (GLP-1) secreting L-cells using murine organoid cultures and the electrophysiological and intracellular signaling pathways recruited following activation of the Gαq-coupled free fatty acid receptors FFA1 and Gαs-coupled bile acid receptors GPBAR1. METHODS: Experiments were performed using ileal organoids generated from mice transgenically expressing fluorescent reporters (Epac2-camps and GCaMP3) under control of the proglucagon promoter. Electrophysiology and single cell imaging were performed on identified L-cells in organoids, and GLP-1 secretion from cultured organoids was measured by immunoassay. RESULTS: The FFA1 ligand TAK-875 triggered L-cell electrical activity, increased intracellular calcium, and activated a depolarizing current that was blocked by the TRPC3 inhibitor Pyr3. TAK-875 triggered GLP-1 secretion was Pyr3 sensitive, suggesting that the TRPC3 channel links FFA1 activation to calcium elevation and GLP-1 release in L-cells. GPBAR1 agonist triggered PKA-dependent L-type Ca2+ current activation and action potential firing in L-cells. The combination of TAK-875 and a GPBAR1 agonist triggered synergistic calcium elevation and GLP-1 secretory responses. CONCLUSIONS: FFA1 and GPBAR1 activation individually increased electrical activity in L-cells by recruiting pathways that include activation of TRPC3 and L-type voltage-gated Ca2+ channels. Synergy between the pathways activated downstream of these receptors was observed both at the level of Ca2+ elevation and GLP-1 secretion.

Description

Keywords

Diabetes, FFA1, GLP-1, GPBAR1, Obesity, Organoid, Animals, Bile Acids and Salts, Calcium, Cells, Cultured, Enteroendocrine Cells, Fatty Acids, Glucagon-Like Peptide 1, Ileum, Membrane Potentials, Mice, Receptors, G-Protein-Coupled, TRPC Cation Channels

Journal Title

Mol Metab

Conference Name

Journal ISSN

2212-8778
2212-8778

Volume Title

7

Publisher

Elsevier BV
Sponsorship
Wellcome Trust (100574/Z/12/Z)
Medical Research Council (MC_UU_12012/5)
Wellcome Trust (106262/Z/14/Z)
Medical Research Council (MC_UU_12012/1)
Medical Research Council (MC_UU_12012/3)
MRC (MC_UU_00014/3)
MRC (MC_UU_00014/5)
Medical Research Council (MC_PC_12012)