title: 5'-AMP-activated protein kinase attenuates adriamycin-induced oxidative podocyte injury through thioredoxin-mediated suppression of the apoptosis signal-regulating kinase 1-P38 signaling pathway.
abstract: Oxidative stress-induced podocyte injury is one of the major mechanisms underlying the initiation and progression of glomerulosclerosis. 5'-AMP-activated protein kinase (AMPK), a serine/threonine kinase that senses intracellular energy status and maintains energy homeostasis, is reported to have antioxidative effects. However, little is known about its application and mechanism. In this study, we investigated whether and how AMPK affected oxidative podocyte injury induced by Adriamycin (ADR; Wako Pure Chemical, Osaka, Japan). Exposure of podocytes to ADR resulted in cell injury, which was preceded by increased reactive oxygen species (ROS) generation and P38 activation. Prevention of oxidative stress with the antioxidant N-acetyl-cysteine and glutathione or inhibition of P38 with SB203580 [4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole] attenuated cell injury. Activation of AMPK with three structurally different AMPK activators also protected podocytes from ADR-elicited cell injury. This effect was associated with strong suppression of oxidative stress-sensitive kinase apoptosis signal-regulating kinase 1 (ASK1) and P38 without obvious influence on ROS level. Further analyses revealed that AMPK promoted thioredoxin (Trx) binding to ASK1. Consistently, AMPK potently suppressed the expression of thioredoxin-interacting protein (TXNIP), a negative regulator of Trx, whereas it significantly enhanced the activity of Trx reductases that convert oxidized Trx to reduced form. In further support of a key role of Trx, downregulation or inhibition of Trx exaggerated but downregulation of TXNIP attenuated the cell injury. These results indicate that AMPK prevents oxidative cell injury through Trx-mediated suppression of ASK1-P38 signaling pathway. Our findings thus provide novel mechanistic insights into the antioxidative actions of AMPK. AMPK could be developed as a novel therapeutic target for treatment of oxidative cell injury.
authors.affiliation: Departments of Molecular Signaling (K.G., Y.C., J.Y.) and Urology (M.T.), Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Yamanashi, Japan; and Department of Nephrology, Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, People's Republic of China (K.G., W.S.).
authors.forename: Kun
authors.initials: K
authors.lastname: Gao
authors.forename: Yuan
authors.initials: Y
authors.lastname: Chi
authors.forename: Wei
authors.initials: W
authors.lastname: Sun
authors.forename: Masayuki
authors.initials: M
authors.lastname: Takeda
authors.forename: Jian
authors.initials: J
authors.lastname: Yao
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D018663:Adrenergic Agents / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D004317:Doxorubicin / Q000494:pharmacology; D004705:Endocytosis / Q000187:drug effects; D048848:MAP Kinase Kinase Kinase 5 / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects*; D050199:Podocytes / Q000187:drug effects* / Q000378:metabolism; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D013879:Thioredoxins / Q000494:pharmacology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D018663:Adrenergic Agents; D018343:Receptors, Adrenergic, beta-2; D013879:Thioredoxins; D004317:Doxorubicin; D000242:Cyclic AMP; D048051:p38 Mitogen-Activated Protein Kinases; D048848:MAP Kinase Kinase Kinase 5; D055372:AMP-Activated Protein Kinases; D002118:Calcium