Phosphorylation and activation of heart PFK-2 by AMPK has a role in the stimulation of glycolysis during ischaemia.
BACKGROUND
The role of protein phosphorylation in the Pasteur effect--the phenomenon whereby anaerobic conditions stimulate glycolysis--has not been addressed. The AMP-activated protein kinase (AMPK) is activated when the oxygen supply is restricted. AMPK acts as an energy-state sensor and inhibits key biosynthetic pathways, thus conserving ATP. Here, we studied whether AMPK is involved in the Pasteur effect in the heart by phosphorylating and activating 6-phosphofructo-2-kinase (PFK-2), the enzyme responsible for the synthesis of fructose 2,6-bisphosphate, a potent stimulator of glycolysis.


RESULTS
Heart PFK-2 was phosphorylated on Ser466 and activated by AMPK in vitro. In perfused rat hearts, anaerobic conditions or inhibitors of oxidative phosphorylation (oligomycin and antimycin) induced AMPK activation, which correlated with PFK-2 activation and with an increase in fructose 2,6-bisphosphate concentration. Moreover, in cultured cells transfected with heart PFK-2, oligomycin treatment resulted in a parallel activation of endogenous AMPK and PFK-2. In these cells, the activation of PFK-2 was due to the phosphorylation of Ser466. A dominant-negative construct of AMPK abolished the activation of endogenous and cotransfected AMPK, and prevented both the activation and phosphorylation of transfected PFK-2 by oligomycin.


CONCLUSIONS
AMPK phosphorylates and activates heart PFK-2 in vitro and in intact cells. AMPK-mediated PFK-2 activation is likely to be involved in the stimulation of heart glycolysis during ischaemia.
Marsin
A S
AS
Hormone and Metabolic Research Unit, Université Catholique de Louvain and Christian de Duve Institute of Cellular Pathology, Brussels, Belgium.
Bertrand
L
L
Rider
M H
MH
Deprez
J
J
Beauloye
C
C
Vincent
M F
MF
Van den Berghe
G
G
Carling
D
D
Hue
L
L
D055372:AMP-Activated Protein Kinases; D000249:Adenosine Monophosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D004734:Energy Metabolism; D004789:Enzyme Activation; D006019:Glycolysis; D006801:Humans; D007700:Kinetics; D008297:Male; D009097:Multienzyme Complexes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017202:Myocardial Ischemia / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D025481:Phosphofructokinase-2; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection
D009097:Multienzyme Complexes; D011994:Recombinant Proteins; D000249:Adenosine Monophosphate; D000255:Adenosine Triphosphate; D017853:Phosphotransferases (Alcohol Group Acceptor); D025481:Phosphofructokinase-2; D017346:Protein Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases