Glucose as regulator of glucose transport activity and glucose-transporter mRNA in hamster beta-cell line.
To investigate the role of glucose in regulating glucose transporters in pancreatic beta-cells, we studied the hamster clonal beta-cell line HIT-T15, which retains responsiveness to glucose. Northern blot analysis demonstrates that GLUT2 and GLUT1 mRNA are abundant in HIT cells. After a 24-h culture with various concentrations of glucose (0-22.2 mM [0-400 mg/dl]), the GLUT2 mRNA level in HIT cells increased by 40% at 22.2 mM (400 mg/dl) glucose compared with 11.1 mM (200 mg/dl) without a change in mRNA stability. It also decreased proportionally to the reduction of glucose concentration. Glucose deprivation resulted in a decrease of GLUT2 mRNA to an almost undetectable level, with a marked increase in the degradation rate of mRNA. In contrast, the GLUT1 mRNA was not affected by glucose. We show that glucose uptake is highest in HIT cells incubated at 2.8-5.5 mM (50-99 mg/dl) glucose for 24 h, and that levels in cells cultured at 0 mM (0 mg/dl) and 22.2 mM (400 mg/dl) glucose decrease to approximately 20% of the maximum level. This decrease is consistent with the effects of glucose on glucose-stimulated insulin secretion in HIT cells. Our results indicate that glucose is involved in regulating GLUT2 mRNA and glucose uptake activity and that the glucose responsiveness of the insulin secretion correlates with the glucose-induced change in glucose uptake activity in HIT cells.
Inagaki
N
N
Department of Medicine, Kyoto University Faculty of Medicine, Japan.
Yasuda
K
K
Inoue
G
G
Okamoto
Y
Y
Yano
H
H
Someya
Y
Y
Ohmoto
Y
Y
Deguchi
K
K
Imagawa
K
K
Imura
H
H
D000818:Animals; D015152:Blotting, Northern; D002478:Cells, Cultured; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D005947:Glucose / Q000494:pharmacology*; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000737:chemistry / Q000166:cytology* / Q000502:physiology; D008297:Male; D008647:Mesocricetus; D009004:Monosaccharide Transport Proteins / Q000235:genetics* / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis* / Q000235:genetics; D051381:Rats; D011919:Rats, Inbred Strains
D007328:Insulin; D009004:Monosaccharide Transport Proteins; D012333:RNA, Messenger; D005947:Glucose