Adenoviral-mediated glucokinase overexpression in rat primary hepatocytes increases the efficiency of glycogen accumulation and lactate production at physiologic glucose concentrations
Glucokinase (GK) catalyses the conversion of glucose to glucose-6-phosphate, and is vital to the liver's role in maintaining glucose homeostasis. To address the effects of altered GK expression on liver carbohydrate metabolism, rat primary hepatocytes were treated with a recombmant adenovirus containing the cDNA of rat liver GK (AdCMVGKL+), and cultured in 1, 3, 5, 10, 15, or 25 mM glucose. GK activity in AdCMVGKL+ hepatocytes was 8.34±0.90-fold (p<0.01, n=9) higher than in controls (untreated hepatocytes, or hepatocytes treated with an adenoviral vector expressing β-galactosidase), and was unaffected by glucose culture conditions. Fold Increase of Glycogen and Lactate in AdCMVCKL+ Over Untreated Hepatocytes 1 3 5 10 15 25 (Glucose (mM)) Glycogen 1.1±0.2 1.7±0.1 4.6±10 18.1±4.1 25.3±3.6 1 5.7±1 .8 Lactae 3.0±0.2 4 9±0-5 5.1±0.3 6.5±0.3 4.7±0.3 3.7±0.2 Importantly, the levels of glycogen and lactate in AdCMVGKL+ hepatocytes cultured in 5mM glucose (230.0±50.0ug/mg protein and 14.94±0.98mM, respectively) were comparable to those observed in controls cultured in 25mM glucose (150.0±20.0ug/mg protein and 7.90±0.36mM, respectively), suggesting that increased glucose phosphorylation due to GK over expression increases the efficiency of glycogen synthesis and glycolysis at physiologic glucose concentrations.
O'Doherty, RM; Lehman, DL; Newgard, CB
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