Regulation of rat brain/HepG2 glucose transporter gene expression by insulin and insulin-like growth factor-I in primary cultures of neuronal and glial cells.
We have demonstrated the expression of the rat brain/HepG2 glucose transporter gene in primary cultures of rat neuronal and glial cells by Northern blot analysis with a rat brain glucose transporter cDNA probe. Incubation of both neuronal and glial cells with insulin and insulin-like growth factor-I induced a time- and dose-dependent increase in the steady state levels of glucose transporter mRNA. The maximal response was achieved between 2-4 h and subsequently decreased. Both insulin and insulin-like growth factor-I at a dose of 1 ng/ml elicited an approximately 57% increase in glucose transporter mRNA levels in neuronal cultures after 90 min, suggesting that each peptide was acting through its own receptor. On the other hand, insulin stimulated [3H]2-deoxyglucose uptake in glial, but not neuronal, cells. These results suggest that insulin-like peptides regulate the expression of the rat brain/Hep G2 glucose transporter gene at both transcriptional and posttranscriptional levels, and that these regulatory mechanisms may be dissociated from each other. Insulin-like peptides may, therefore, participate in the control of brain energy metabolism.
Werner
H
H
Section on Molecular and Cellular Physiology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892.
Raizada
M K
MK
Mudd
L M
LM
Foyt
H L
HL
Simpson
I A
IA
Roberts
C T
CT
LeRoith
D
D
D000818:Animals; D001921:Brain / Q000378:metabolism*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects*; D005947:Glucose / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D009004:Monosaccharide Transport Proteins / Q000235:genetics* / Q000378:metabolism; D009457:Neuroglia / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D013002:Somatomedins / Q000494:pharmacology*
D007328:Insulin; D009004:Monosaccharide Transport Proteins; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D005947:Glucose