Effects of genetic deletion of soluble 5'-nucleotidases NT5C1A and NT5C2 on AMPK activation and nucleotide levels in contracting mouse skeletal muscles.
AMP-activated protein kinase (AMPK) plays a key role in energy homeostasis and is activated in response to contraction-induced ATP depletion in skeletal muscle via a rise in intracellular AMP/ADP concentrations. AMP can be deaminated by AMP-deaminase (AMPD) to IMP, which is hydrolyzed to inosine by cytosolic 5'-nucleotidase II (NT5C2). AMP can also be hydrolyzed to adenosine by cytosolic 5'-nucleotidase 1A (NT5C1A). Previous gene silencing and overexpression studies indicated control of AMPK activation by NT5C enzymes. In the present study using gene knockout mouse models, we investigated the effects of NT5C1A and NT5C2 deletion on intracellular adenine nucleotide levels and AMPK activation in electrically stimulated skeletal muscles. Surprisingly, NT5C enzyme knockout did not lead to enhanced AMP or ADP concentrations in response to contraction, with no potentiation of increases in AMPK activity in extensor digitorum longus (EDL) and soleus mouse muscles. Moreover, dual blockade of AMP metabolism in EDL using an AMPD inhibitor combined with NT5C1A deletion did not enhance rises in AMP and ADP or increased AMPK activation by electrical stimulation. The results on muscles from the NT5C knockout mice contradict previous findings where AMP levels and AMPK activity were shown to be modulated by NT5C enzymes.
de Duve Institute, Université catholique de Louvain, Brussels, Belgium.
Samanta
S
Kviklyte
de Duve Institute, Université catholique de Louvain, Brussels, Belgium.
Didier
D
Vertommen
Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium; and.
Xavier
X
Yerna
AstraZeneca Research and Development, Mölndal, Sweden.
Harriet
H
Andersén
AstraZeneca Research and Development, Mölndal, Sweden.
Xiufeng
X
Xu
Institute of Neuroscience, Université catholique de Louvain, Brussels, Belgium; and.
Philippe
P
Gailly
AstraZeneca Research and Development, Mölndal, Sweden.
Mohammad
M
Bohlooly-Y
AstraZeneca Research and Development, Mölndal, Sweden.
Jan
J
Oscarsson
de Duve Institute, Université catholique de Louvain, Brussels, Belgium; mark.rider@uclouvain.be.
Mark H
MH
Rider
D015720:5'-Nucleotidase; D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000244:Adenosine Diphosphate / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D004789:Enzyme Activation; D017353:Gene Deletion; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D009711:Nucleotides / Q000378:metabolism; D012995:Solubility
D009711:Nucleotides; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D055372:AMP-Activated Protein Kinases; D015720:5'-Nucleotidase; C000621979:NT5C1A protein, mouse; C000621981:NT5C2 protein, mouse
AMPK; NT5C1A; NT5C2; contraction; muscle