Key points are not available for this paper at this time.
Although metabolic conditions associated with an increased AMP/ATP ratio are primary factors in the activation of 5′-adenosine monophosphate-activated protein kinase (AMPK), a number of recent studies have shown that increased intracellular levels of reactive oxygen species can stimulate AMPK activity, even without a decrease in cellular levels of ATP. We found that exposure of recombinant AMPKαβγ complex or HEK 293 cells to H2O2 was associated with increased kinase activity and also resulted in oxidative modification of AMPK, including S-glutathionylation of the AMPKα and AMPKβ subunits. In experiments using C-terminal truncation mutants of AMPKα (amino acids 1–312), we found that mutation of cysteine 299 to alanine diminished the ability of H2O2 to induce kinase activation, and mutation of cysteine 304 to alanine totally abrogated the enhancing effect of H2O2 on kinase activity. Similar to the results obtained with H2O2-treated HEK 293 cells, activation and S-glutathionylation of the AMPKα subunit were present in the lungs of acatalasemic mice or mice treated with the catalase inhibitor aminotriazole, conditions in which intracellular steady state levels of H2O2 are increased. These results demonstrate that physiologically relevant concentrations of H2O2 can activate AMPK through oxidative modification of the AMPKα subunit. The present findings also imply that AMPK activation, in addition to being a response to alterations in intracellular metabolic pathways, is directly influenced by cellular redox status. Although metabolic conditions associated with an increased AMP/ATP ratio are primary factors in the activation of 5′-adenosine monophosphate-activated protein kinase (AMPK), a number of recent studies have shown that increased intracellular levels of reactive oxygen species can stimulate AMPK activity, even without a decrease in cellular levels of ATP. We found that exposure of recombinant AMPKαβγ complex or HEK 293 cells to H2O2 was associated with increased kinase activity and also resulted in oxidative modification of AMPK, including S-glutathionylation of the AMPKα and AMPKβ subunits. In experiments using C-terminal truncation mutants of AMPKα (amino acids 1–312), we found that mutation of cysteine 299 to alanine diminished the ability of H2O2 to induce kinase activation, and mutation of cysteine 304 to alanine totally abrogated the enhancing effect of H2O2 on kinase activity. Similar to the results obtained with H2O2-treated HEK 293 cells, activation and S-glutathionylation of the AMPKα subunit were present in the lungs of acatalasemic mice or mice treated with the catalase inhibitor aminotriazole, conditions in which intracellular steady state levels of H2O2 are increased. These results demonstrate that physiologically relevant concentrations of H2O2 can activate AMPK through oxidative modification of the AMPKα subunit. The present findings also imply that AMPK activation, in addition to being a response to alterations in intracellular metabolic pathways, is directly influenced by cellular redox status. IntroductionAMPK 3The abbreviations used are: AMPK5′-adenosine monophosphate-activated protein kinaseROSreactive oxygen speciesATZ3-amino-1,2,4-triazoleAIDautoinhibitory domainGOglucose oxidaseDCF2′,7′-dichlorodihydrofluoresceinDCF-DA2′,7′-dichlorodihydrofluorescein diacetateGSSS-glutathionylation ofBIAMbiotinylated iodoacetamideACCacetyl-CoA carboxylase. is a serine/threonine kinase that consists of three subunits, of which the α subunit has inducible kinase activity and the β and γ subunits have regulatory function. Formation of the αβγ complex is required for optimal allosteric activation of AMPK, which is induced by binding of AMP to the γ subunit (1Baron S.J. Li J. Russell 3rd, R.R. Neumann D. Miller E.J. Tuerk R. Wallimann T. Hurley R.L. Witters L.A. Young L.H. Circ. Res. 2005; 96: 337-345Crossref PubMed Scopus (86) Google Scholar, 2Hardie D.G. Hawley S.A. Scott J.W. J. Physiol. 2006; 574: 7-15Crossref PubMed Scopus (644) Google Scholar, 3Scott J.W. Hawley S.A. Green K.A. Anis M. Stewart G. Scullion G.A. Norman D.G. Hardie D.G. J. Clin. Invest. 2004; 113: 274-284Crossref PubMed Scopus (599) Google Scholar, 4Towler M.C. Hardie D.G. Circ. Res. 2007; 100: 328-341Crossref PubMed Scopus (1039) Google Scholar). In addition to activation by AMP, phosphorylation of the Thr172 residue of the α subunit enhances kinase activity (5Stein S.C. Woods A. Jones N.A. Davison M.D. Carling D. Biochem. J. 2000; 345: 437-443Crossref PubMed Scopus (484) Google Scholar, 6Hawley S.A. Davison M. Woods A. Davies S.P. Beri R.K. Carling D. Hardie D.G. J. Biol. Chem. 1996; 271: 27879-27887Abstract Full Text Full Text PDF PubMed Scopus (995) Google Scholar). Recent studies have shown that the autoinhibitory domain (AID), located between amino acids 312 and 335 of the AMPKα subunit, is responsible for the lack of kinase activity under basal conditions (7Crute B.E. Seefeld K. Gamble J. Kemp B.E. Witters L.A. J. Biol. Chem. 1998; 273: 35347-35354Abstract Full Text Full Text PDF PubMed Scopus (305) Google Scholar, 8Pang T. Xiong B. Li J.Y. Qiu B.Y. Jin G.Z. Shen J.K. Li J. J. Biol. Chem. 2007; 282: 495-506Abstract Full Text Full Text PDF PubMed Scopus (90) Google Scholar, 9Chen L. Jiao Z.H. Zheng L.S. Zhang Y.Y. Xie S.T. Wang Z.X. Wu J.W. Nature. 2009; 459: 1146-1149Crossref PubMed Scopus (161) Google Scholar), whereas AMP-induced conformational changes within the αβγ complex diminish function of the AID and lead to kinase activation.The regulation of AMPK activity is primarily thought to result from alterations in the intracellular AMP/ATP ratio, arising from diminished ATP generation due to hypoxia, glucose deprivation, heat shock, or reduction in mitochondrial oxidative phosphorylation or from increased ATP consumption, such as occurs during strenuous exercise (2Hardie D.G. Hawley S.A. Scott J.W. J. Physiol. 2006; 574: 7-15Crossref PubMed Scopus (644) Google Scholar, 10Evans A.M. Mustard K.J. Wyatt C.N. Peers C. Dipp M. Kumar P. Kinnear N.P. Hardie D.G. J. Biol. Chem. 2005; 280: 41504-41511Abstract Full Text Full Text PDF PubMed Scopus (156) Google Scholar, 11Yun H. Lee M. Kim S.S. Ha J. J. Biol. Chem. 2005; 280: 9963-9972Abstract Full Text Full Text PDF PubMed Scopus (133) Google Scholar, 12Winder W.W. Holmes B.F. Rubink D.S. Jensen E.B. Chen M. Holloszy J.O. J. Appl. Physiol. 2000; 88: 2219-2226Crossref PubMed Scopus (591) Google Scholar). Once activated, AMPK can phosphorylate and modulate the function of essential metabolic pathways participating in the regulation of glucose and lipid homeostasis (13Dolinsky V.W. Dyck J.R. Am. J. Physiol. Heart Circ. Physiol. 2006; 291: H2557-H2569Crossref PubMed Scopus (115) Google Scholar, 14Long Y.C. Zierath J.R. J. Clin. Invest. 2006; 116: 1776-1783Crossref PubMed Scopus (745) Google Scholar, 15Hardie D.G. Sakamoto K. Physiology. 2006; 21: 48-60Crossref PubMed Scopus (427) Google Scholar). A major effect of AMPK activation is in preserving energy for use under conditions where ATP is limiting (4Towler M.C. Hardie D.G. Circ. Res. 2007; 100: 328-341Crossref PubMed Scopus (1039) Google Scholar, 16Hardie D.G. Scott J.W. Pan D.A. Hudson E.R. FEBS Lett. 2003; 546: 113-120Crossref PubMed Scopus (705) Google Scholar). AMPK activation appears to prevent or diminish inflammation-associated organ injury, including the development of atherosclerotic cardiovascular disease in diabetes (17Knowler W.C. Barrett-Connor E. Fowler S.E. Hamman R.F. Lachin J.M. Walker E.A. Nathan D.M. N. Engl. J. Med. 2002; 346: 393-403Crossref PubMed Scopus (14330) Google Scholar), ischemia-induced cardiac dysfunction (18Shibata R. Sato K. Pimentel D.R. Takemura Y. Kihara S. Ohashi K. Funahashi T. Ouchi N. Walsh K. Nat. Med. 2005; 11: 1096-1103Crossref PubMed Scopus (847) Google Scholar, 19Shin E.J. Schram K. Zheng X.L. Sweeney G. J. Cell. Physiol. 2009; 221: 490-497Crossref PubMed Scopus (54) Google Scholar, 20Gundewar S. Calvert J.W. Jha S. Toedt-Pingel I. Ji S.Y. Nunez D. Ramachandran A. Anaya-Cisneros M. Tian R. Lefer D.J. Circ. Res. 2009; 104: 403-411Crossref PubMed Scopus (315) Google Scholar), and hepatic dysfunction in animal models of nonalcoholic steatohepatitis as well as in humans with this condition (21Lin H.Z. Yang S.Q. Chuckaree C. Kuhajda F. Ronnet G. Diehl A.M. Nat. Med. 2000; 6: 998-1003Crossref PubMed Scopus (608) Google Scholar, 22Marchesini G. Brizi M. Bianchi G. Tomassetti S. Zoli M. Melchionda N. Lancet. 2001; 358: 893-894Abstract Full Text Full Text PDF PubMed Scopus (627) Google Scholar). Our studies have also suggested that therapeutic approaches to increase AMPK activity diminish the severity of LPS-induced acute lung injury in mice (23Zhao X. Zmijewski J.W. Lorne E. Liu G. Park Y.J. Tsuruta Y. Abraham E. Am. J. Physiol. Lung Cell Mol. Physiol. 2008; 295: L497-L504Crossref PubMed Scopus (249) Google Scholar, 24Zmijewski J.W. Lorne E. Zhao X. Tsuruta Y. Sha Y. Liu G. Siegal G.P. Abraham E. Am. J. Respir. Crit. Care Med. 2008; 178: 168-179Crossref PubMed Scopus (126) Google Scholar).Although increased formation of reactive oxygen species (ROS) is generally thought to be associated with pathophysiological situations leading to cellular injury and organ dysfunction, recent studies have shown beneficial effects of ROS in modulating inflammation, including TLR4-induced neutrophil activation and LPS-associated acute lung injury (24Zmijewski J.W. Lorne E. Zhao X. Tsuruta Y. Sha Y. Liu G. Siegal G.P. Abraham E. Am. J. Respir. Crit. Care Med. 2008; 178: 168-179Crossref PubMed Scopus (126) Google Scholar, 25Zmijewski J.W. Lorne E. Zhao X. Tsuruta Y. Sha Y. Liu G. Abraham E. Am. J. Respir. Crit. Care Med. 2009; 179: 694-704Crossref PubMed Scopus (79) Google Scholar, 26Zmijewski J.W. Zhao X. Xu Z. Abraham E. Am. J. Physiol. Cell Physiol. 2007; 293: C255-C266Crossref PubMed Scopus (59) Google Scholar, 27Strassheim D. Asehnoune K. Park J.S. Kim J.Y. He Q. Richter D. Mitra S. Arcaroli J. Kuhn K. Abraham E. Am. J. Physiol. Cell Physiol. 2004; 286: C683-C692Crossref PubMed Scopus (52) Google Scholar). Several studies have demonstrated that increased intracellular concentrations of H2O2 result in activation of AMPK and enhancement of AMPK-mediated cellular adaptation (28Horie T. Ono K. Nagao K. Nishi H. Kinoshita M. Kawamura T. Wada H. Shimatsu A. Kita T. Hasegawa K. J. Cell. Physiol. 2008; 215: 733-742Crossref PubMed Scopus (103) Google Scholar, 29Irrcher I. Ljubicic V. Hood D.A. Am. J. Physiol. Cell Physiol. 2009; PubMed Scopus Google Scholar, Zhang S.J. J. H. A. J. Physiol. 2006; PubMed Scopus Google Scholar), including of redox homeostasis E. J. S. Chen K. A. P. T. 2008; PubMed Google Scholar, S. Biochem. J. 2009; PubMed Scopus Google Scholar). In cardiac diminished activation of AMPK and resulted in increased severity of cardiac injury R.R. G. N. J. S.A. 2009; PubMed Scopus Google the ability of increased intracellular concentrations of H2O2 to induce AMPK activation in the for this effect has well that activation of AMPK resulted from ATP and increased AMP/ATP Kim S.J. Lee Kim J. J. Kim S. Ha J. Biochem. Res. 2001; PubMed Scopus (249) Google Scholar), studies demonstrated that increased intracellular concentrations of H2O2 were associated with activation of AMPK or without in the ratio F. C. Z. B. Biol. Med. 2009; PubMed Scopus Google Scholar, T. T. L. S. M. S. K. H. K. G. A. Sato K. T. K. Am. J. Physiol. 2004; PubMed Scopus Google Scholar, M. Y. Xu J. Xie Z. Wu Y. P. M. Wu J. Circ. Res. 2008; PubMed Scopus Google can pathways as a result of oxidative modification of cysteine in Physiol. 2002; PubMed Scopus Google Scholar, D. R. A. R. I. J. Cell Mol. Med. 2004; PubMed Scopus Google Scholar, I. R. D. R. A. Biol. Med. 2007; PubMed Scopus Google Scholar). We that a by which increased intracellular concentrations of H2O2 can activate AMPK is through of in or AMPK subunits. Our present experiments demonstrate that exposure to H2O2 is associated with cysteine in the AMPKα subunit and is to directly activate this we demonstrated that H2O2 can directly activate AMPK in and in through a associated with oxidative including S-glutathionylation of cysteine of the AMPKα subunit. shown that exposure of to H2O2 or to that increased intracellular concentrations of such as by mitochondrial result in increased AMPK activity I. Ljubicic V. Hood D.A. Am. J. Physiol. Cell Physiol. 2009; PubMed Scopus Google Scholar, F. C. Z. B. Biol. Med. 2009; PubMed Scopus Google Scholar, M. Y. Xu J. Xie Z. Wu Y. P. M. Wu J. Circ. Res. 2008; PubMed Scopus Google Scholar, K. A. N. M. M. Cell 2007; 6: Full Text Full Text PDF PubMed Scopus Google Scholar). The ability of H2O2 to activate AMPK has to be and to through intracellular levels of ATP and the ratio of AMP to enhancing binding of AMP to the subunit with allosteric activation of the AMPKα kinase domain Kim S.J. Lee Kim J. J. Kim S. Ha J. Biochem. Res. 2001; PubMed Scopus (249) Google Scholar). A recent that an of the subunit suggested that the effects of H2O2 on AMPK activation are by a diminished ratio S.A. C. Green K.A. A. S. M.C. A.M. Hardie D.G. Cell 11: Full Text Full Text PDF PubMed Scopus Google Scholar). in the present we found that exposure of cells to increased levels of H2O2 and AMPK decrease in ATP levels or in the ratio we that H2O2 directly activate AMPK by that of the AMPKαβγ complex with H2O2 increased kinase activity. exposure of HEK 293 and to H2O2 also results in diminished intracellular ATP levels and increased AMP/ATP in addition to intracellular concentrations of the ability of H2O2 to directly activate AMPK imply that this is the major by which increased generation of H2O2 activation of AMPK in experiments be to the of of the AMPKα subunit as with alterations in AMP/ATP in AMPK during such as injury, that are associated with increased of exposure to H2O2 resulted in oxidative modification and S-glutathionylation of the α and β subunits of AMPK, modification of the AMPKα subunit was to increase kinase activity. exposure of AMPKα (amino acids which the binding domain for with the AMPKβ and subunits, to H2O2 increased AMPK activity, that with the β and γ subunits was for AMPK activation by Recent studies have shown that between of the AID and of the AMPKα subunit is responsible for of the of the AMPKα subunit within the AMPKαβγ complex (7Crute B.E. Seefeld K. Gamble J. Kemp B.E. Witters L.A. J. Biol. Chem. 1998; 273: 35347-35354Abstract Full Text Full Text PDF PubMed Scopus (305) Google Scholar, 8Pang T. Xiong B. Li J.Y. Qiu B.Y. Jin G.Z. Shen J.K. Li J. J. Biol. Chem. 2007; 282: 495-506Abstract Full Text Full Text PDF PubMed Scopus (90) Google Scholar, 9Chen L. Jiao Z.H. Zheng L.S. Zhang Y.Y. Xie S.T. Wang Z.X. Wu J.W. Nature. 2009; 459: 1146-1149Crossref PubMed Scopus (161) Google Scholar). exposure of AMPKα or AMPKα truncation mutants the AID to H2O2 resulted in AMPK kinase activity, that the AID is to an in this of cysteine 299 and mutation of cysteine 304 totally the activation of AMPKα by that oxidative modification of an in the ability of H2O2 to induce activation of results that exposure to H2O2 enhances the kinase activity of AMPK, phosphorylation of AMPK was also present under such In of the AMPKαβγ complex with H2O2 increased phosphorylation of the AMPKα and AMPKβ subunits. findings are with studies that that AMPK during activation D. Dyck J. Gamble J. C. Witters L.A. Kemp B.E. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar).Although H2O2 is a H2O2 is of cellular to of intracellular and to modulate activity in pathways Physiol. 2002; PubMed Scopus Google Scholar). The results of the present and of that exposure of the AMPKαβγ complex or of the AMPKα subunit to H2O2 increased kinase activity and diminished that the by which H2O2 such effects is through oxidative modification of cysteine The ability of H2O2 to S-glutathionylation of the AMPKα and AMPKβ subunits is with this Although the present findings that exposure to H2O2 is to and activate AMPK, is that such as from H2O2 to we found that generation of in diminished the activity of AMPK results that H2O2 is responsible for activation of AMPK under in conditions associated with increased generation of to the effects of H2O2 in we found that increased intracellular concentrations of H2O2 in the lungs under in conditions also were associated with AMPK activation L.H. 2008; PubMed Scopus Google Scholar). A for H2O2 in modulating AMPK activity in was cardiac increased levels of H2O2 in the were by activation of AMPK and from a (1Baron S.J. Li J. Russell 3rd, R.R. Neumann D. Miller E.J. Tuerk R. Wallimann T. Hurley R.L. Witters L.A. Young L.H. Circ. Res. 2005; 96: 337-345Crossref PubMed Scopus (86) Google Scholar, N. R.L. S. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar, E. C. Physiol. 2008; 88: PubMed Scopus Google Scholar, 3rd, R.R. Li J. M. C. M. J. Young L.H. J. Clin. Invest. 2004; PubMed Scopus Google Scholar, A. S. Q. G. Shen M. Sakamoto K. Tian R. A. J. Cell. Physiol. 2007; PubMed Scopus (115) Google Scholar). with experiments with AMPK and with HEK 293 cells, we found activation of AMPK and oxidative modification of the AMPKα subunit in the lungs of acatalasemic mice and in mice treated with the catalase inhibitor conditions in which intracellular concentrations of H2O2 are J.W. Lorne E. Zhao X. Tsuruta Y. Sha Y. Liu G. Abraham E. Am. J. Respir. Crit. Care Med. 2009; 179: 694-704Crossref PubMed Scopus (79) Google experiments demonstrate a for AMPK activation that oxidative modification of the AMPKα subunit as a result of exposure to H2O2 studies have shown that activation of AMPK as well as increased intracellular concentrations of H2O2 have including diminished severity of LPS-induced acute lung injury J.W. Lorne E. Zhao X. Tsuruta Y. Sha Y. Liu G. Abraham E. Am. J. Respir. Crit. Care Med. 2009; 179: 694-704Crossref PubMed Scopus (79) Google Scholar). The present experiments that by which H2O2 effects in is through directly studies be to the primary for the effects of increased intracellular concentrations of H2O2 is through activation of IntroductionAMPK 3The abbreviations used are: AMPK5′-adenosine monophosphate-activated protein kinaseROSreactive oxygen speciesATZ3-amino-1,2,4-triazoleAIDautoinhibitory domainGOglucose oxidaseDCF2′,7′-dichlorodihydrofluoresceinDCF-DA2′,7′-dichlorodihydrofluorescein diacetateGSSS-glutathionylation ofBIAMbiotinylated iodoacetamideACCacetyl-CoA carboxylase. is a serine/threonine kinase that consists of three subunits, of which the α subunit has inducible kinase activity and the β and γ subunits have regulatory function. Formation of the αβγ complex is required for optimal allosteric activation of AMPK, which is induced by binding of AMP to the γ subunit (1Baron S.J. Li J. Russell 3rd, R.R. Neumann D. Miller E.J. Tuerk R. Wallimann T. Hurley R.L. Witters L.A. Young L.H. Circ. Res. 2005; 96: 337-345Crossref PubMed Scopus (86) Google Scholar, 2Hardie D.G. Hawley S.A. Scott J.W. J. Physiol. 2006; 574: 7-15Crossref PubMed Scopus (644) Google Scholar, 3Scott J.W. Hawley S.A. Green K.A. Anis M. Stewart G. Scullion G.A. Norman D.G. Hardie D.G. J. Clin. Invest. 2004; 113: 274-284Crossref PubMed Scopus (599) Google Scholar, 4Towler M.C. Hardie D.G. Circ. Res. 2007; 100: 328-341Crossref PubMed Scopus (1039) Google Scholar). In addition to activation by AMP, phosphorylation of the Thr172 residue of the α subunit enhances kinase activity (5Stein S.C. Woods A. Jones N.A. Davison M.D. Carling D. Biochem. J. 2000; 345: 437-443Crossref PubMed Scopus (484) Google Scholar, 6Hawley S.A. Davison M. Woods A. Davies S.P. Beri R.K. Carling D. Hardie D.G. J. Biol. Chem. 1996; 271: 27879-27887Abstract Full Text Full Text PDF PubMed Scopus (995) Google Scholar). Recent studies have shown that the autoinhibitory domain (AID), located between amino acids 312 and 335 of the AMPKα subunit, is responsible for the lack of kinase activity under basal conditions (7Crute B.E. Seefeld K. Gamble J. Kemp B.E. Witters L.A. J. Biol. Chem. 1998; 273: 35347-35354Abstract Full Text Full Text PDF PubMed Scopus (305) Google Scholar, 8Pang T. Xiong B. Li J.Y. Qiu B.Y. Jin G.Z. Shen J.K. Li J. J. Biol. Chem. 2007; 282: 495-506Abstract Full Text Full Text PDF PubMed Scopus (90) Google Scholar, 9Chen L. Jiao Z.H. Zheng L.S. Zhang Y.Y. Xie S.T. Wang Z.X. Wu J.W. Nature. 2009; 459: 1146-1149Crossref PubMed Scopus (161) Google Scholar), whereas AMP-induced conformational changes within the αβγ complex diminish function of the AID and lead to kinase activation.The regulation of AMPK activity is primarily thought to result from alterations in the intracellular AMP/ATP ratio, arising from diminished ATP generation due to hypoxia, glucose deprivation, heat shock, or reduction in mitochondrial oxidative phosphorylation or from increased ATP consumption, such as occurs during strenuous exercise (2Hardie D.G. Hawley S.A. Scott J.W. J. Physiol. 2006; 574: 7-15Crossref PubMed Scopus (644) Google Scholar, 10Evans A.M. Mustard K.J. Wyatt C.N. Peers C. Dipp M. Kumar P. Kinnear N.P. Hardie D.G. J. Biol. Chem. 2005; 280: 41504-41511Abstract Full Text Full Text PDF PubMed Scopus (156) Google Scholar, 11Yun H. Lee M. Kim S.S. Ha J. J. Biol. Chem. 2005; 280: 9963-9972Abstract Full Text Full Text PDF PubMed Scopus (133) Google Scholar, 12Winder W.W. Holmes B.F. Rubink D.S. Jensen E.B. Chen M. Holloszy J.O. J. Appl. Physiol. 2000; 88: 2219-2226Crossref PubMed Scopus (591) Google Scholar). Once activated, AMPK can phosphorylate and modulate the function of essential metabolic pathways participating in the regulation of glucose and lipid homeostasis (13Dolinsky V.W. Dyck J.R. Am. J. Physiol. Heart Circ. Physiol. 2006; 291: H2557-H2569Crossref PubMed Scopus (115) Google Scholar, 14Long Y.C. Zierath J.R. J. Clin. Invest. 2006; 116: 1776-1783Crossref PubMed Scopus (745) Google Scholar, 15Hardie D.G. Sakamoto K. Physiology. 2006; 21: 48-60Crossref PubMed Scopus (427) Google Scholar). A major effect of AMPK activation is in preserving energy for use under conditions where ATP is limiting (4Towler M.C. Hardie D.G. Circ. Res. 2007; 100: 328-341Crossref PubMed Scopus (1039) Google Scholar, 16Hardie D.G. Scott J.W. Pan D.A. Hudson E.R. FEBS Lett. 2003; 546: 113-120Crossref PubMed Scopus (705) Google Scholar). AMPK activation appears to prevent or diminish inflammation-associated organ injury, including the development of atherosclerotic cardiovascular disease in diabetes (17Knowler W.C. Barrett-Connor E. Fowler S.E. Hamman R.F. Lachin J.M. Walker E.A. Nathan D.M. N. Engl. J. Med. 2002; 346: 393-403Crossref PubMed Scopus (14330) Google Scholar), ischemia-induced cardiac dysfunction (18Shibata R. Sato K. Pimentel D.R. Takemura Y. Kihara S. Ohashi K. Funahashi T. Ouchi N. Walsh K. Nat. Med. 2005; 11: 1096-1103Crossref PubMed Scopus (847) Google Scholar, 19Shin E.J. Schram K. Zheng X.L. Sweeney G. J. Cell. Physiol. 2009; 221: 490-497Crossref PubMed Scopus (54) Google Scholar, 20Gundewar S. Calvert J.W. Jha S. Toedt-Pingel I. Ji S.Y. Nunez D. Ramachandran A. Anaya-Cisneros M. Tian R. Lefer D.J. Circ. Res. 2009; 104: 403-411Crossref PubMed Scopus (315) Google Scholar), and hepatic dysfunction in animal models of nonalcoholic steatohepatitis as well as in humans with this condition (21Lin H.Z. Yang S.Q. Chuckaree C. Kuhajda F. Ronnet G. Diehl A.M. Nat. Med. 2000; 6: 998-1003Crossref PubMed Scopus (608) Google Scholar, 22Marchesini G. Brizi M. Bianchi G. Tomassetti S. Zoli M. Melchionda N. Lancet. 2001; 358: 893-894Abstract Full Text Full Text PDF PubMed Scopus (627) Google Scholar). Our studies have also suggested that therapeutic approaches to increase AMPK activity diminish the severity of LPS-induced acute lung injury in mice (23Zhao X. Zmijewski J.W. Lorne E. Liu G. Park Y.J. Tsuruta Y. Abraham E. Am. J. Physiol. Lung Cell Mol. Physiol. 2008; 295: L497-L504Crossref PubMed Scopus (249) Google Scholar, 24Zmijewski J.W. Lorne E. Zhao X. Tsuruta Y. Sha Y. Liu G. Siegal G.P. Abraham E. Am. J. Respir. Crit. Care Med. 2008; 178: 168-179Crossref PubMed Scopus (126) Google Scholar).Although increased formation of reactive oxygen species (ROS) is generally thought to be associated with pathophysiological situations leading to cellular injury and organ dysfunction, recent studies have shown beneficial effects of ROS in modulating inflammation, including TLR4-induced neutrophil activation and LPS-associated acute lung injury (24Zmijewski J.W. Lorne E. Zhao X. Tsuruta Y. Sha Y. Liu G. Siegal G.P. Abraham E. Am. J. Respir. Crit. Care Med. 2008; 178: 168-179Crossref PubMed Scopus (126) Google Scholar, 25Zmijewski J.W. Lorne E. Zhao X. Tsuruta Y. Sha Y. Liu G. Abraham E. Am. J. Respir. Crit. Care Med. 2009; 179: 694-704Crossref PubMed Scopus (79) Google Scholar, 26Zmijewski J.W. Zhao X. Xu Z. Abraham E. Am. J. Physiol. Cell Physiol. 2007; 293: C255-C266Crossref PubMed Scopus (59) Google Scholar, 27Strassheim D. Asehnoune K. Park J.S. Kim J.Y. He Q. Richter D. Mitra S. Arcaroli J. Kuhn K. Abraham E. Am. J. Physiol. Cell Physiol. 2004; 286: C683-C692Crossref PubMed Scopus (52) Google Scholar). Several studies have demonstrated that increased intracellular concentrations of H2O2 result in activation of AMPK and enhancement of AMPK-mediated cellular adaptation (28Horie T. Ono K. Nagao K. Nishi H. Kinoshita M. Kawamura T. Wada H. Shimatsu A. Kita T. Hasegawa K. J. Cell. Physiol. 2008; 215: 733-742Crossref PubMed Scopus (103) Google Scholar, 29Irrcher I. Ljubicic V. Hood D.A. Am. J. Physiol. Cell Physiol. 2009; PubMed Scopus Google Scholar, Zhang S.J. J. H. A. J. Physiol. 2006; PubMed Scopus Google Scholar), including of redox homeostasis E. J. S. Chen K. A. P. T. 2008; PubMed Google Scholar, S. Biochem. J. 2009; PubMed Scopus Google Scholar). In cardiac diminished activation of AMPK and resulted in increased severity of cardiac injury R.R. G. N. J. S.A. 2009; PubMed Scopus Google the ability of increased intracellular concentrations of H2O2 to induce AMPK activation in the for this effect has well that activation of AMPK resulted from ATP and increased AMP/ATP Kim S.J. Lee Kim J. J. Kim S. Ha J. Biochem. Res. 2001; PubMed Scopus (249) Google Scholar), studies demonstrated that increased intracellular concentrations of H2O2 were associated with activation of AMPK or without in the ratio F. C. Z. B. Biol. Med. 2009; PubMed Scopus Google Scholar, T. T. L. S. M. S. K. H. K. G. A. Sato K. T. K. Am. J. Physiol. 2004; PubMed Scopus Google Scholar, M. Y. Xu J. Xie Z. Wu Y. P. M. Wu J. Circ. Res. 2008; PubMed Scopus Google can pathways as a result of oxidative modification of cysteine in Physiol. 2002; PubMed Scopus Google Scholar, D. R. A. R. I. J. Cell Mol. Med. 2004; PubMed Scopus Google Scholar, I. R. D. R. A. Biol. Med. 2007; PubMed Scopus Google Scholar). We that a by which increased intracellular concentrations of H2O2 can activate AMPK is through of in or AMPK subunits. Our present experiments demonstrate that exposure to H2O2 is associated with cysteine in the AMPKα subunit and is to directly activate
Zmijewski et al. (Sat,) studied this question.
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