Overlap of Endocrine Hormone Expression in the Mouse Intestine Revealed by Transcriptional Profiling and Flow Cytometry

Abstract

The intestine secretes a range of hormones with important local and distant actions, including the control of insulin secretion and appetite. A number of enteroendocrine cell types have been described, each characterized by a distinct hormonal signature, such as K-cells producing glucose-dependent insulinotropic polypeptide (GIP), L-cells producing glucagon-like peptide-1 (GLP-1), and I-cells producing cholecystokinin (CCK). To evaluate similarities between L-, K-, and other enteroendocrine cells, primary murine L- and K-cells, and pancreatic α- and β-cells, were purified and analyzed by flow cytometry and microarray-based transcriptomics. By microarray expression profiling, L cells from the upper small intestinal (SI) more closely resembled upper SI K-cells than colonic L-cells. Upper SI L-cell populations expressed message for hormones classically localized to different enteroendocrine cell types, including GIP, CCK, secretin, and neurotensin. By immunostaining and fluorescence-activated cell sorting analysis, most colonic L-cells contained GLP-1 and PeptideYY In the upper SI, most L-cells contained CCK, approximately 10% were GIP positive, and about 20% were PeptideYY positive. Upper SI K-cells exhibited approximately 10% overlap with GLP-1 and 6% overlap with somatostatin. Enteroendocrine-specific transcription factors were identified from the microarrays, of which very few differed between the enteroendocrine cell populations. Etv1, Prox1, and Pax4 were significantly enriched in L-cells vs. K cells by quantitative RT-PCR. In summary, our data indicate a strong overlap between upper SI L-, K-, and I-cells and suggest they may rather comprise a single cell type, within which individual cells exhibit a hormonal spectrum that may reflect factors such as location along the intestine and exposure to dietary nutrients.

Glucagon-Like Peptide-1 Receptor Agonists Increase Pancreatic Mass by Induction of Protein Synthesis

“…Although GLP-1R agonists robustly increased insulin secretion and lowered glycemia in hGLP1R:Glp1r 2/2 mice, Ex-4 had no effect on pancreatic mass or pancreatic expression of Reg3a or Reg3b in hGLP1R:Glp1r 2/2 mice (14), indicating that increased levels of insulin are not sufficient to mediate the effects of GLP-1R agonists on the exocrine pancreas. CCK activates GLP-1-containing neurons in the central nervous system (29,30), and GLP-1 and CCK are colocalized in and secreted from subsets of enteroendocrine L cells (31). Pancreatic growth is readily induced by CCK administration or administration of exogenous protease/trypsin inhibitors that elevate levels of CCK (32).…”

Insulin-like peptide 5 is an orexigenic gastrointestinal hormone

“…Indeed, glucagon-like peptide-1 (GLP-1) analogs and inhibitors of GLP-1 degradation are now widely prescribed for the treatment of type 2 diabetes, offering additional beneficial effects on body weight compared with conventional insulin secretagogues (5,6). As increasing evidence implicates enteroendocrine L-cells, which secrete GLP-1 together with the anorectic peptides oxyntomodulin and peptideYY (PYY), as substantial players in postbariatric physiology (7), a question that has raised considerable interest is whether L-cells or their close relatives (8,9) produce additional peptides of therapeutic significance.…”

De nouveaux types cellulaires identifiés par séquençage haut débit sur cellule unique

“…Les cellules caliciformes, elles, sécrètent le mucus néces-saire à la protection de l'épithélium. Enfin, les cellules entéro-endocrines, représentées par de nombreux soustypes, régulent le métabolisme en produisant plus d'une dizaine d'hormones, chaque sous-type n'en sécrétant qu'un nombre restreint [3,4]. En sus de ces quatre types principaux, d'autres types existent.…”