Cell Mol Gastroenterol Hepatol. 2022 Feb 23. pii: S2352-345X(22)00038-8. [Epub ahead of print]
BACKGROUND AIMS: Leucine-rich repeat-containing G-protein coupled receptor-5 (Lgr5)+/olfactomedin-4 (Olfm4)+ intestinal stem cells (ISCs) in the crypt-base are crucial for homeostatic maintenance of the epithelium. The gut hormone, glucagon-like peptide-21-33 (GLP-2), stimulates intestinal proliferation and growth; however, the actions of GLP-2 on the Lgr5+ ISCs remain unclear. The aim of this study was to determine whether and how GLP-2 regulates Lgr5+ ISC cell cycle dynamics and number.METHODS: Lgr5-eGFP-IRES-creERT2 mice were acutely administered human Gly2-GLP-2, or the GLP-2 receptor antagonist, GLP-23-33. Intestinal epithelial-insulin-like growth factor-1 receptor knockout and control mice were treated chronically with hGly2-GLP-2. Cell cycle parameters were determined by EdU, BrdU, Ki67 and phosphohistone-3 labeling and cell cycle gene expression.
RESULTS: Acute hGly2-GLP-2 treatment increased the proportion of eGFP+EdU+/OLFM4+EdU+ cells by 11-22% (p<0.05), without affecting other cell cycle markers. hGly2-GLP-2 treatment also increased the ratio of eGFP+ cells in early-to-late S-phase by 97% (p<0.001), and increased the proportion of eGFP+ cells entering S-phase by 218% (p<0.001). hGly2-GLP-2 treatment induced jejunal expression of genes involved in cell cycle regulation (p<0.05), and increased expression of Mcm3 in the Lgr5-expressing cells by 122% (p<0.05). Conversely. GLP-23-33 reduced the proportion of eGFP+EdU+ cells by 27% (p<0.05), as well as the expression of jejunal cell cycle genes (p<0.05). Finally, chronic hGly2-GLP-2 treatment increased the number of OLFM4+ cells/crypt (p<0.05), in an intestinal epithelial insulin-like growth factor-1 receptor-dependent manner.
CONCLUSIONS: These findings expand the actions of GLP-2 to encompass acute stimulation of Lgr5+ ISC S-phase entry through the GLP-2R, and chronic induction of Lgr5+ ISC expansion through downstream intestinal insulin-like growth factor-1 signaling.
Keywords: Cell cycle; GLP-2; Lgr5; Olfm4; S-phase; intestine; proliferation