Possible involvement of the alpha1 isoform of 5'AMP-activated protein kinase in oxidative stress-stimulated glucose transport in skeletal muscle.
Recent studies have suggested that 5'AMP-activated protein kinase (AMPK) is activated in response to metabolic stresses, such as contraction, hypoxia, and the inhibition of oxidative phosphorylation, which leads to insulin-independent glucose transport in skeletal muscle. In the present study, we hypothesized that acute oxidative stress increases the rate of glucose transport via an AMPK-mediated mechanism. When rat epitrochlearis muscles were isolated and incubated in vitro in Krebs buffer containing the oxidative agent H(2)O(2), AMPKalpha1 activity increased in a time- and dose-dependent manner, whereas AMPKalpha2 activity remained unchanged. The activation of AMPKalpha1 was associated with phosphorylation of AMPK Thr(172), suggesting that an upstream kinase is involved in the activation process. H(2)O(2)-induced AMPKalpha1 activation was blocked in the presence of the antioxidant N-acetyl-l-cysteine (NAC), and H(2)O(2) significantly increased the ratio of oxidized glutathione to glutathione (GSSG/GSH) concentrations, a sensitive marker of oxidative stress. H(2)O(2) did not cause an increase in the conventional parameters of AMPK activation, such as AMP and AMP/ATP. H(2)O(2) increased 3-O-methyl-d-glucose transport, and this increase was partially, but significantly, blocked in the presence of NAC. Results were similar when the muscles were incubated in a superoxide-generating system using hypoxanthine and xanthine oxidase. Taken together, our data suggest that acute oxidative stress activates AMPKalpha1 in skeletal muscle via an AMP-independent mechanism and leads to an increase in the rate of glucose transport, at least in part, via an AMPKalpha1-mediated mechanism.
Toyoda
Taro
T
Dept. of Medicine and Clinical Science, Kyoto Univ. Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto, 606-8507, Japan.
Hayashi
Tatsuya
T
Miyamoto
Licht
L
Yonemitsu
Shin
S
Nakano
Masako
M
Tanaka
Satsuki
S
Ebihara
Ken
K
Masuzaki
Hiroaki
H
Hosoda
Kiminori
K
Inoue
Gen
G
Otaka
Akira
A
Sato
Kenji
K
Fushiki
Tohru
T
Nakao
Kazuwa
K
D055372:AMP-Activated Protein Kinases; D000111:Acetylcysteine / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005947:Glucose / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism; D007930:Leucine / Q000031:analogs & derivatives* / Q000494:pharmacology; D008297:Male; D009097:Multienzyme Complexes / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
C568306:(3-ethoxycarbonyloxirane-2-carbonyl)leucine (3-methylbutyl) amide; D007527:Isoenzymes; D009097:Multienzyme Complexes; D006861:Hydrogen Peroxide; D017346:Protein Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases; D007930:Leucine; D005947:Glucose; D000111:Acetylcysteine