Development and regulation of glucose transporter and hexokinase expression in rat.
The ontogenesis of the glucose transporters GLUT-1, GLUT-2, and GLUT-4 and the hexokinases HK-I, HK-II, and HK-IV (glucokinase) was studied in rat tissues. In brown adipose tissue, high levels of GLUT-4 and HK-II were observed during fetal life; both decreased at birth and then increased throughout development. At birth, cold exposure increased GLUT-4 and HK-II expression in brown adipose tissue, whereas fasting decreased it. GLUT-1 and HK-I were present in fetal muscle, but GLUT-4 and HK-II were absent. The coordinate appearance of GLUT-4 and HK-II in skeletal muscle was concomitant with the acquisition of insulin sensitivity after weaning. In the heart, the glucose transporter isoform switched from GLUT-1 to GLUT-4 during the suckling period. The coordinate expression of GLUT-4 and HK-II in heart was observed after weaning. GLUT-2, detected in fetal liver, increased throughout development. GLUT-1 and HK-I were detectable in fetal liver, whereas glucokinase appeared after weaning. Consumption of a high-carbohydrate diet after weaning increased GLUT-4 and HK-II in muscle and GLUT-2 in liver, whereas consumption of a high-fat diet prevented these changes. These results showed that 1) GLUT-1 and HK-I are abundant in most fetal rat tissues, 2) GLUT-4 and HK-II expression is associated with the appearance of tissue insulin sensitivity, and 3) GLUT-2 is expressed early in liver, before the appearance of glucokinase.
Postic
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Centre de Recherche sur l'Endocrinologie Moléculaire et le Développement, Centre National de la Recherche Scientifique, Meudon Bellevue, France.
Leturque
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A
Printz
R L
RL
Maulard
P
P
Loizeau
M
M
Granner
D K
DK
Girard
J
J
D002001:Adipose Tissue, Brown / Q000196:embryology / Q000378:metabolism; D000375:Aging / Q000378:metabolism*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D000831:Animals, Newborn; D005333:Fetus / Q000378:metabolism* / Q000502:physiology; D005941:Glucokinase / Q000235:genetics; D006321:Heart / Q000196:embryology; D006593:Hexokinase / Q000235:genetics / Q000378:metabolism*; D008099:Liver / Q000378:metabolism; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
D009004:Monosaccharide Transport Proteins; D012333:RNA, Messenger; D006593:Hexokinase; D005941:Glucokinase