Allosteric activation of pyruvate kinase via NAD+ in rat liver cells.
In isolated rat hepatocytes, it has previously been reported that a rise in the ATP content induces a proportional increase in cytosolic NAD+ concentration [Devin, A., Guérin, B. & Rigoulet, M. (1997) FEBS Lett. 410, 329-332]. This occurs under physiological conditions such as various substrates or different energetic states. To investigate the effect of a physiological rise in cytosolic [NAD+] per se on glycolysis and gluconeogenesis, an increase in [NAD+] induced by exogenous nicotinamide addition was obtained without a change in redox potential, ATP/ADP ratio and ATP concentration. Using dihydroxyacetone as substrate, we found that an increase in cytosolic [NAD+] decreases gluconeogenesis and enhances glycolysis without significant alteration of dihydroxyacetone consumption rate. These modifications are the consequence of an allosteric activation of pyruvate kinase via cytosolic NAD+ content. Thus, in addition to the well-known thermodynamic control of glycolysis by pyridine-nucleotide redox status, our study points to a new mechanism of glycolytic flux regulation by NAD+ concentration at the level of pyruvate kinase activity.
Devin
A
A
NIH, NCI, Bldg 10, Room 6 N105, Bethesda, MD 20892, USA.
Nogueira
V
V
Leverve
X
X
Guérin
B
B
Rigoulet
M
M
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000494:Allosteric Regulation; D000818:Animals; D002469:Cell Separation; D004099:Dihydroxyacetone Phosphate / Q000378:metabolism; D004734:Energy Metabolism; D019344:Lactic Acid / Q000378:metabolism; D008099:Liver / Q000201:enzymology*; D008297:Male; D009243:NAD / Q000378:metabolism*; D009536:Niacinamide / Q000494:pharmacology; D010728:Phosphoenolpyruvate / Q000378:metabolism; D011770:Pyruvate Kinase / Q000378:metabolism*; D019289:Pyruvic Acid / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
D009243:NAD; D009536:Niacinamide; D019344:Lactic Acid; D004099:Dihydroxyacetone Phosphate; D000244:Adenosine Diphosphate; D010728:Phosphoenolpyruvate; D019289:Pyruvic Acid; D000255:Adenosine Triphosphate; D011770:Pyruvate Kinase