TISSUE-SPECIFIC AND GLUCOSE-DEPENDENT EXPRESSION OF RECEPTOR GENES FOR GLUCAGON AND GLUCAGON-LIKE PEPTIDE-1 (GLP-1)

Both glucagon and glucagon-like peptide-1 (GLP-1) play an important ro le in the regulation of nutrient homeostasis. In this study, the tissu e distributions of the expression of receptor genes for glucagon and G LP-1 were examined. Expression of glucagon receptor gene was detected in liver, kidney, ileum and pancreatic islets but not in brain. In con trast, expression of GLP-1 receptor gene was detected in brain, pancre as and pancreatic islets but not in liver, kidney, or ileum. To invest igate the existence and characteristics of glucagon and GLP-1 receptor s on pancreatic beta cells, expression of the receptor genes and trans lational regulation of the expression of the receptor genes by glucose were analyzed in a mouse pancreatic beta cell line, MIN6 cells. In th e cDNA pool of MIN6 cells, both glucagon and GLP-1 receptor genes were identified and showed higher expression level in MIN6 cells cultured under high glucose condition than in those cultured under low glucose condition. These results suggest that glucagon and GLP-1 receptor gene s are expressed in pancreatic beta cells and their expression is upreg ulated by glucose.