AMPK-mediated AS160 phosphorylation in skeletal muscle is dependent on AMPK catalytic and regulatory subunits.
AMP-activated protein kinase (AMPK) is a heterotrimeric protein that regulates glucose transport mediated by cellular stress or pharmacological agonists such as 5-aminoimidazole-4-carboxamide 1 beta-d-ribonucleoside (AICAR). AS160, a Rab GTPase-activating protein, provides a mechanism linking AMPK signaling to glucose uptake. We show that AICAR increases AMPK, acetyl-CoA carboxylase, and AS160 phosphorylation by insulin-independent mechanisms in isolated skeletal muscle. Recombinant AMPK heterotrimeric complexes (alpha1beta1gamma1 and alpha2beta2gamma1) phosphorylate AS160 in a cell-free assay. In mice deficient in AMPK signaling (alpha2 AMPK knockout [KO], alpha2 AMPK kinase dead [KD], and gamma3 AMPK KO), AICAR effects on AS160 phosphorylation were severely blunted, highlighting that complexes containing alpha2 and gamma3 are necessary for AICAR-stimulated AS160 phosphorylation in intact skeletal muscle. Contraction-mediated AS160 phosphorylation was also impaired in alpha2 AMPK KO and KD but not gamma3 AMPK KO mice. Our results implicate AS160 as a downstream target of AMPK.
Treebak
Jonas T
JT
Department of Molecular Medicine and Surgery, Section for Integrative Physiology, Karolinska Institute, von Eulers väg 4, 4th Floor, S-171 77 Stockholm, Sweden.
Glund
Stephan
S
Deshmukh
Atul
A
Klein
Ditte K
DK
Long
Yun Chau
YC
Jensen
Thomas E
TE
Jørgensen
Sebastian B
SB
Viollet
Benoit
B
Andersson
Leif
L
Neumann
Dietbert
D
Wallimann
Theo
T
Richter
Erik A
EA
Chibalin
Alexander V
AV
Zierath
Juleen R
JR
Wojtaszewski
Jørgen F P
JF
D000263:Adenylate Kinase / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport; D002384:Catalysis; D020690:GTPase-Activating Proteins / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology; D007700:Kinetics; D051379:Mice; D018345:Mice, Knockout; D018482:Muscle, Skeletal / Q000201:enzymology*; D010766:Phosphorylation; D021122:Protein Subunits / Q000378:metabolism; D012265:Ribonucleotides / Q000494:pharmacology
D020690:GTPase-Activating Proteins; D007328:Insulin; D021122:Protein Subunits; D012265:Ribonucleotides; C505647:Tbc1d4 protein, mouse; D000620:Aminoimidazole Carboxamide; D000263:Adenylate Kinase; C031143:AICA ribonucleotide; D005947:Glucose