Abstract
Epithelial-mesenchymal transition (EMT) plays a pivotal role in the pathogenesis of renal tubulointerstitial fibrosis. We previously demonstrated that aldosterone (Aldo)-induced EMT is dependent on mitochondrial-derived oxidative stress. This study investigated whether mitochondrial dysfunction (MtD) is involved in the pathogenesis of EMT and whether peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), a major regulator of oxidative metabolism and mitochondrial function, prevents EMT by improving MtD. Aldo decreased PGC-1α expression while increasing its acetylation and induced MtD, as evidenced by oxidative stress, mitochondrial membrane potential collapse, mitochondrial DNA damage, and mitochondrial complex activity reduction. Aldo time-dependently induced p66Shc phosphorylation and expression. Mineralocorticoid receptor antagonist eplerenone and p66Shc short interfering RNA prevented Aldo-induced MtD and EMT, as evidenced by downregulation of α-smooth muscle actin and upregulation of E-cadherin. Mitochondrial DNA depletion by ethidium bromide or mitochondrial transcription factor A inhibitory RNA (RNAi) induced MtD, further promoting EMT. RNAi-mediated suppression of PGC-1α induced MtD and EMT, whereas overexpression of PGC-1α prevented Aldo-induced MtD and inhibited EMT. Similarly, overexpression of silent mating type information regulation 2 homolog 1 (SIRT1), a gene upstream of PGC-1α, or the SIRT1 activator resveratrol restored Aldo-induced MtD and EMT by upregulating PGC-1α. These findings, which implicate a role for MtD in EMT and suggest that SIRT1 and PGC-1α coordinate to improve mitochondrial function and EMT, may guide us in therapeutic strategies for renal tubulointerstitial fibrosis.
Copyright © 2012 Elsevier Inc. All rights reserved.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Aldosterone / pharmacology*
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Blotting, Western
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Cadherins / genetics
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Cadherins / metabolism
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Cells, Cultured
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DNA Damage / drug effects*
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DNA, Mitochondrial / genetics
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism
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Epithelial Cells / drug effects*
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Epithelial Cells / metabolism
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Epithelial Cells / pathology
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Epithelial-Mesenchymal Transition / drug effects*
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Heat-Shock Proteins / antagonists & inhibitors
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Heat-Shock Proteins / genetics
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Heat-Shock Proteins / metabolism
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Humans
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Kidney Tubules, Proximal / cytology
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Kidney Tubules, Proximal / drug effects*
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Kidney Tubules, Proximal / metabolism
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Membrane Potential, Mitochondrial / drug effects
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Mitochondria / drug effects*
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Mitochondria / metabolism
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Mitochondria / pathology*
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Mitochondrial Proteins / genetics
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Mitochondrial Proteins / metabolism
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Oxidative Stress / drug effects
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Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha
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Phosphorylation / drug effects
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Protein Processing, Post-Translational
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RNA, Messenger / genetics
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RNA, Small Interfering / genetics
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Real-Time Polymerase Chain Reaction
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Reverse Transcriptase Polymerase Chain Reaction
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Shc Signaling Adaptor Proteins / antagonists & inhibitors
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Shc Signaling Adaptor Proteins / genetics
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Shc Signaling Adaptor Proteins / metabolism
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Sirtuin 1
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Src Homology 2 Domain-Containing, Transforming Protein 1
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Transcription Factors / antagonists & inhibitors
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Transcription Factors / genetics
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Transcription Factors / metabolism
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Transcriptional Activation
Substances
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Cadherins
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DNA, Mitochondrial
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DNA-Binding Proteins
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Heat-Shock Proteins
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Mitochondrial Proteins
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PPARGC1A protein, human
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Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha
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RNA, Messenger
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RNA, Small Interfering
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SHC1 protein, human
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Shc Signaling Adaptor Proteins
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Src Homology 2 Domain-Containing, Transforming Protein 1
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TFAM protein, human
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Transcription Factors
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Aldosterone
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SIRT1 protein, human
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Sirtuin 1