Selective tonic inhibition of G-6-Pase catalytic subunit, but not G-6-P transporter, gene expression by insulin in vivo.

Hornbuckle LA, Edgerton DS, Ayala JE, Svitek CA, Oeser JK, Neal DW, Cardin S, Cherrington AD, O'Brien RM
Am J Physiol Endocrinol Metab. 2001 281 (4): E713-25

PMID: 11551847 · DOI:10.1152/ajpendo.2001.281.4.E713

The regulation of glucose-6-phosphatase (G-6-Pase) catalytic subunit and glucose 6-phosphate (G-6-P) transporter gene expression by insulin in conscious dogs in vivo and in tissue culture cells in situ were compared. In pancreatic-clamped, euglycemic conscious dogs, a 5-h period of hypoinsulinemia led to a marked increase in hepatic G-6-Pase catalytic subunit mRNA; however, G-6-P transporter mRNA was unchanged. In contrast, a 5-h period of hyperinsulinemia resulted in a suppression of both G-6-Pase catalytic subunit and G-6-P transporter gene expression. Similarly, insulin suppressed G-6-Pase catalytic subunit and G-6-P transporter gene expression in H4IIE hepatoma cells. However, the magnitude of the insulin effect was much greater on G-6-Pase catalytic subunit gene expression and was manifested more rapidly. Furthermore, cAMP stimulated G-6-Pase catalytic subunit expression in H4IIE cells and in primary hepatocytes but had no effect on G-6-P transporter expression. These results suggest that the relative control strengths of the G-6-Pase catalytic subunit and G-6-P transporter in the G-6-Pase reaction are likely to vary depending on the in vivo environment.

MeSH Terms (26)

Animals Antiporters Base Sequence Blood Glucose Catalysis Cells, Cultured Cyclophilin A Dogs Gene Expression Regulation Gene Expression Regulation, Enzymologic Glucose-6-Phosphatase Humans Hyperinsulinism Insulin Islets of Langerhans Mice Molecular Sequence Data Monosaccharide Transport Proteins Polymerase Chain Reaction Protein Subunits Rats RNA, Messenger Sequence Alignment Sequence Homology, Nucleic Acid Swine Transcription, Genetic

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