2021
Endocrinology. 2021 Mar 1;162(3):bqaa246. doi: 10.1210/endocr/bqaa246.
Using a Reporter Mouse to Map Known and Novel Sites of GLP-1 Receptor Expression in Peripheral Tissues of Male Mice
Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Panum Institute, Copenhagen, Denmark. Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark. Department of Endocrinology and Nephrology, Nordsjællands Hospital Hillerød, University of Copenhagen, Hillerød, Denmark.
Service type: Knock-in mice
Abstract
Glucagon-like peptide-1 receptor (GLP-1R) activation is used in the treatment of diabetes and obesity; however, GLP-1 induces many other physiological effects with unclear mechanisms of action. To identify the cellular targets of GLP-1 and GLP-1 analogues, we generated a Glp1r.tdTomato reporter mouse expressing the reporter protein, tdTomato, in Glp1r-expressing cells. The reporter signal is expressed in all cells where GLP-1R promoter was ever active. To complement this, we histologically mapped tdTomato-fluorescence, and performed Glp-1r mRNA in situ hybridization and GLP-1R immunohistochemistry on the same tissues. In male mice, we found tdTomato signal in mucus neck, chief, and parietal cells of the stomach; Brunner's glands; small intestinal enteroendocrine cells and intraepithelial lymphocytes; and myenteric plexus nerve fibers throughout the gastrointestinal tract. Pancreatic acinar-, β-, and δ cells, but rarely α cells, were tdTomato-positive, as were renal arteriolar smooth muscle cells; endothelial cells of the liver, portal vein, and endocardium; aortal tunica media; and lung type 1 and type 2 pneumocytes. Some thyroid follicular and parafollicular cells displayed tdTomato expression, as did tracheal cartilage chondrocytes, skin fibroblasts, and sublingual gland mucus cells. In conclusion, our reporter mouse is a powerful tool for mapping known and novel sites of GLP-1R expression in the mouse, thus enhancing our understanding of the many target cells and effects of GLP-1 and GLP-1R agonists. Keywords: glucagon-like peptide-1; glucagon-like peptide-1 receptor; reporter mouse.
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