Regulation of Glucose Transporter Messenger RNA Levels in Rat Adipose Tissue by Insulin

William I. Sivitz, Susan L. DeSautel, Toshiaki Kayano, Graeme I. Bell, Jeffrey E. Pessin
1990 Molecular Endocrinology  
Analysis of glucose transporter mRNA levels in adipose tissue from streptozotocin (STZ)-induced diabetic rats demonstrated a specific decrease (10fold) in adipose tissue GLUT-4 mRNA with no significant effect on GLUT-1 mRNA levels. Treatment of STZ-diabetic rats with twice daily injections of insulin for 1-3 days resulted in a 16-fold increase in the relative amount of GLUT-4 mRNA to levels approximately 2-fold greater than those in control animals. However, after 7 days of insulin therapy the
more » ... mount of GLUT-4 mRNA decreased approximately 2-fold back to the levels in the control animals. Normalization of the STZ-induced serum hyperglycemia by phlorizin treatment, which inhibits renal tubular reabsorption of glucose, had no effect on GLUT-4 mRNA in the absence of insulin. Similar to STZ-diabetes, fasting for 48 h also reduced adipose GLUT-4 mRNA levels. Parenteral administration of insulin with glucose over 7.5 h, but not glucose alone, increased the levels of the GLUT-4 mRNA 3to 4-fold. These studies demonstrate that the relative glycemic state does not influence GLUT-4 glucose transporter mRNA expression in vivo and strongly suggests that insulin is a major factor regulating the levels of GLUT-4 mRNA in adipose tissue. (Molecular Endocrinology 4: 583-588, 1990) 1 We have employed the following abbreviations for the facilitative glucose transporters: GLUT-1 is the erythrocyte/ HepG2/rat brain glucose transporter (9, 10); GLUT-2 is the liver/islet glucose transporter having 55% sequence identity with the GLUT-1 protein (6, 8); GLUT-3 is the glucose transporter isolated from a human fetal muscle cDNA library having 64% sequence identity with the GLUT-1 protein and is expressed in most tissues (7) ; and GLUT-4 is the predominant glucose transporter expressed in adipose and muscle tissues (11 -15) having 65% amino acid sequence identity to the GLUT-1 protein. 583 Downloaded from by guest on
doi:10.1210/mend-4-4-583 pmid:2149165 fatcat:g65tbe6uzjf7toojtl3a2xpma4