GPR119 Agonist AS1269574 Activates TRPA1 Cation Channels to Stimulate GLP-1 Secretion

Mol Endocrinol. 2016 Jun;30(6):614-29. doi: 10.1210/me.2015-1306. Epub 2016 Apr 15.

Abstract

GPR119 is a G protein-coupled receptor expressed on intestinal L cells that synthesize and secrete the blood glucose-lowering hormone glucagon-like peptide-1 (GLP-1). GPR119 agonists stimulate the release of GLP-1 from L cells, and for this reason there is interest in their potential use as a new treatment for type 2 diabetes mellitus. AS1269574 is one such GPR119 agonist, and it is the prototype of a series of 2,4,6 trisubstituted pyrimidines that exert positive glucoregulatory actions in mice. Here we report the unexpected finding that AS1269574 stimulates GLP-1 release from the STC-1 intestinal cell line by directly promoting Ca(2+) influx through transient receptor potential ankyrin 1 (TRPA1) cation channels. These GPR119-independent actions of AS1269574 are inhibited by TRPA1 channel blockers (AP-18, A967079, HC030031) and are not secondary to intracellular Ca(2+) release or cAMP production. Patch clamp studies reveal that AS1269574 activates an outwardly rectifying membrane current with properties expected of TRPA1 channels. However, the TRPA1 channel-mediated action of AS1269574 to increase intracellular free calcium concentration is not replicated by GPR119 agonists (AR231453, oleoylethanolamide) unrelated in structure to AS1269574. Using human embryonic kidney-293 cells expressing recombinant rat TRPA1 channels but not GPR119, direct TRPA1 channel activating properties of AS1269574 are validated. Because we find that AS1269574 also acts in a conventional GPR119-mediated manner to stimulate proglucagon gene promoter activity in the GLUTag intestinal L cell line, new findings reported here reveal the surprising capacity of AS1269574 to act as a dual agonist at two molecular targets (GPR119/TRPA1) important to the control of L-cell function and type 2 diabetes mellitus drug discovery research.

MeSH terms

  • Animals
  • Calcium / metabolism
  • Cyclic AMP / metabolism
  • Cyclic AMP-Dependent Protein Kinases / metabolism
  • Cymenes
  • Endoplasmic Reticulum / drug effects
  • Endoplasmic Reticulum / metabolism
  • Ethanolamines / pharmacology*
  • Gene Expression Regulation / drug effects
  • Glucagon / metabolism
  • Glucagon-Like Peptide 1 / metabolism*
  • HEK293 Cells
  • Humans
  • Ion Channel Gating / drug effects*
  • Isothiocyanates / pharmacology
  • Luciferases / metabolism
  • Monoterpenes / pharmacology
  • Mutant Proteins / metabolism
  • Proglucagon / genetics
  • Proglucagon / metabolism
  • Pyrimidines / pharmacology*
  • Rats
  • Receptors, G-Protein-Coupled / antagonists & inhibitors*
  • Recombinant Proteins / pharmacology
  • TRPA1 Cation Channel / metabolism*
  • Transfection

Substances

  • 2-(2-(4-bromophenyl)-6-methylpyrimidin-4-yl)aminoethanol
  • Cymenes
  • Ethanolamines
  • Isothiocyanates
  • Monoterpenes
  • Mutant Proteins
  • Pyrimidines
  • Receptors, G-Protein-Coupled
  • Recombinant Proteins
  • TRPA1 Cation Channel
  • Proglucagon
  • 2,3,4-tri-O-acetylarabinopyranosyl isothiocyanate
  • Glucagon-Like Peptide 1
  • Glucagon
  • carvacrol
  • Cyclic AMP
  • Luciferases
  • Cyclic AMP-Dependent Protein Kinases
  • Calcium