Oligopeptides stimulate glucagon-like peptide-1 secretion in mice through proton-coupled uptake and the calcium-sensing receptor

Diabetologia. 2013 Dec;56(12):2688-96. doi: 10.1007/s00125-013-3037-3. Epub 2013 Sep 18.


Aims/hypothesis: Ingested protein is a well-recognised stimulus for glucagon-like peptide-1 (GLP-1) release from intestinal L cells. This study aimed to characterise the molecular mechanisms employed by L cells to detect oligopeptides.

Methods: GLP-1 secretion from murine primary colonic cultures and Ca(2+) dynamics in L cells were monitored in response to peptones and dipeptides. L cells were identified and purified based on their cell-specific expression of the fluorescent protein Venus, using GLU-Venus transgenic mice. Pharmacological tools and knockout mice were used to characterise candidate sensory pathways identified by expression analysis.

Results: GLP-1 secretion was triggered by peptones and di-/tripeptides, including the non-metabolisable glycine-sarcosine (Gly-Sar). Two sensory mechanisms involving peptide transporter-1 (PEPT1) and the calcium-sensing receptor (CaSR) were distinguishable. Responses to Gly-Sar (10 mmol/l) were abolished in the absence of extracellular Ca(2+) or by the L-type calcium-channel blocker nifedipine (10 μmol/l) and were PEPT1-dependent, as demonstrated by their sensitivity to pH and 4-aminomethylbenzoic acid and the finding of impaired responses in tissue from Pept1 (also known as Slc15a1) knockout mice. Peptone (5 mg/ml)-stimulated Ca(2+) responses were insensitive to nifedipine but were blocked by antagonists of CaSR. Peptone-stimulated GLP-1 secretion was not impaired in mice lacking the putative peptide-responsive receptor lysophosphatidic acid receptor 5 (LPAR5; also known as GPR92/93).

Conclusions/interpretation: Oligopeptides stimulate GLP-1 secretion through PEPT1-dependent electrogenic uptake and activation of CaSR. Both pathways are highly expressed in native L cells, and likely contribute to the ability of ingested protein to elevate plasma GLP-1 levels. Targeting nutrient-sensing pathways in L cells could be used to mobilise endogenous GLP-1 stores in humans, and could mimic some of the metabolic benefits of bariatric surgery.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / metabolism*
  • Calcium Channels, L-Type / metabolism*
  • Cell Line
  • Cyclic AMP / metabolism
  • Enteroendocrine Cells / metabolism*
  • Glucagon-Like Peptide 1 / metabolism*
  • Mice
  • Mice, Knockout
  • Mice, Transgenic
  • Oligopeptides / metabolism*
  • Peptones / metabolism
  • Prediabetic State / metabolism*
  • Protons
  • Receptors, Calcium-Sensing / metabolism*
  • Receptors, Glucagon / metabolism
  • Signal Transduction


  • Calcium Channels, L-Type
  • Oligopeptides
  • Peptones
  • Protons
  • Receptors, Calcium-Sensing
  • Receptors, Glucagon
  • Glucagon-Like Peptide 1
  • Cyclic AMP
  • Calcium