Regulation of glucokinase and GLUT-2 glucose-transporter gene expression in pancreatic B-cells.
Glucokinase (EC 2.7.1.2) is the signal-recognition enzyme in pancreatic B-cells for initiation of glucose-induced insulin secretion. We show here that both the glucokinase and glucose-transporter GLUT-2 genes are regulated physiologically. Fasting decreased B-cell glucokinase and glucose-transporter GLUT-2 mRNA in pancreatic B-cells as well as in liver, whereas refeeding induced expression of both genes. In pancreatic B-cells a approximately 4.4 kb glucokinase-related mRNA was detectable, in addition to the 2.8 kb form. This approximately 4.4 kb glucokinase transcript was drastically decreased during refeeding. The 2.8 kb mRNA, which is typical for pancreatic B-cells, was accompanied after refeeding by a 2.4 kb mRNA species typical for liver glucokinase. Starvation primarily decreased the 2.8 kb pancreatic B-cell glucokinase mRNA species. The concordant regulation of both genes may represent the basis for the physiological regulation of glucose-induced insulin secretion at a transcriptional level.
Tiedge
M
M
Institute of Pharmacology and Toxicology, University of Göttingen, Germany.
Lenzen
S
S
D000818:Animals; D005215:Fasting; D015971:Gene Expression Regulation, Enzymologic; D005941:Glucokinase / Q000235:genetics*; D007515:Islets of Langerhans / Q000201:enzymology / Q000378:metabolism*; D008099:Liver / Q000737:chemistry; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D009004:Monosaccharide Transport Proteins; D012333:RNA, Messenger; D005941:Glucokinase