scholarly journals SIRT3 deficiency promotes lung fibrosis by augmenting alveolar epithelial cell mitochondrial DNA damage and apoptosis

2017 ◽  
Vol 31 (6) ◽  
pp. 2520-2532 ◽  
Author(s):  
Renea P. Jablonski ◽  
Seok‐Jo Kim ◽  
Paul Cheresh ◽  
David B. Williams ◽  
Luisa Morales‐Nebreda ◽  
...  
Keyword(s):  
Dna Damage ◽  
Mitochondrial Dna ◽  
Epithelial Cell ◽  
Lung Fibrosis ◽  
Alveolar Epithelial Cell ◽  
Alveolar Epithelial ◽  
Mitochondrial Dna Damage

ID: 140: KLOTHO, AN ANTI-AGING MOLECULE, REGULATES ALVEOLAR EPITHELIAL CELL MTDNA DAMAGE AND APOPTOSIS

2016 ◽  
Vol 64 (4) ◽  
pp. 961.1-961
Author(s):  
S Kim ◽  
P Cheresh ◽  
RP Jablonski ◽  
DW Kamp ◽  
M Eren ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Dna Damage ◽  
Epithelial Cell ◽  
Pulmonary Fibrosis ◽  
Oxidative Dna Damage ◽  
Alveolar Epithelial Cell ◽  
Premature Aging ◽  
Protective Effects ◽  
Mtdna Damage ◽  
Alveolar Epithelial

RationaleConvincing evidence has emerged that impaired alveolar epithelial cell (AEC) injury and repair resulting from ‘exaggerated’ lung aging and mitochondrial dysfunction are critical determinants of the lung fibrogenic potential of toxic agents, including asbestos fibers, but the mechanisms underlying these findings is unknown. We showed that the extent of AEC mitochondrial DNA (mtDNA) damage and apoptosis are critical determinants of asbestos-induced pulmonary fibrosis (Cheresh et al AJRCMB 2014, Kim et al JBC 2014). Klotho is an age-inhibiting gene and Klotho-deficient mice demonstrate a premature aging phenotype that includes a reduced lifespan, arteriosclerosis, and lung oxidative DNA damage, and that Klotho attenuates hyperoxic-induced AEC DNA damage and apoptosis (Ravikumar et al AJP-Lung 2014). We reason that Klotho has an important role in limiting pulmonary fibrosis by protecting the AECs from oxidative stress.MethodsQuantitative PCR-based measurement of mtDNA damage was assessed following transient transfection with wild-type Klotho, Klotho siRNA or AKT siRNA in A549 and/or MLE-12 cells for 48 hrs followed by exposure to either amosite asbestos (25 µg/cm2) or H2O2 (200 µM) for 24 hrs. Apoptosis was assessed by cleaved caspase-9/3 levels and DNA fragmentation assay. Murine pulmonary fibrosis was analyzed in male 8–10 week old WT (C3H/C57B6J) mice or Klotho heterozygous knockout (Kl+/−) mice following intratracheal instillation of a single dose of 100 µg crocidolite asbestos or titanium dioxide (negative control) using histology (fibrosis score by Masson's trichrome staining) and lung collagen (Sircoll assay).ResultsCompared to control, amosite asbestos or H2O2 reduces Klotho mRNA/protein expression. Notably, silencing of Klotho promotes oxidative stress-induced AEC mtDNA damage and apoptosis whereas Klotho-enforced expression (EE) and Euk-134, a mitochondrial ROS scavenger, are protective. Interestingly, Kl+/− mice have increased asbestos-induced lung fibrosis. Also, we find that inhibition or silencing of AKT augments oxidant-induced AEC mtDNA damage and apoptosis.ConclusionsOur data demonstrate a crucial role for AEC AKT signaling in mediating the mtDNA damage protective effects of Klotho. Given the importance of AEC aging and apoptosis in pulmonary fibrosis, we reason that Klotho/AKT axis is an innovative therapeutic target for preventing common lung diseases of aging (i.e. IPF, COPD, lung cancer, etc.) for which more effective management regimens are clearly needed.FundingNIH-RO1 ES020357-01A1 (DK) and VA Merit (DK).

scholarly journals TRIM72 promotes alveolar epithelial cell membrane repair and ameliorates lung fibrosis

2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Xiaofei Cong ◽  
Nagaraja Nagre ◽  
Jeremy Herrera ◽  
Andrew C. Pearson ◽  
Ian Pepper ◽  
...  
Keyword(s):  
Epithelial Cell ◽  
Cell Membrane ◽  
Lung Fibrosis ◽  
Alveolar Epithelial Cell ◽  
Membrane Repair ◽  
Alveolar Epithelial

Mitochondrial-derived free radicals mediate asbestos-induced alveolar epithelial cell apoptosis

2004 ◽  
Vol 286 (6) ◽  
pp. L1220-L1227 ◽  
Author(s):  
Vijayalakshmi Panduri ◽  
Sigmund A. Weitzman ◽  
Navdeep S. Chandel ◽  
David W. Kamp
Keyword(s):  
Mitochondrial Dna ◽  
Electron Transport ◽  
Epithelial Cell ◽  
Dna Fragmentation ◽  
Alveolar Epithelial Cell ◽  
A549 Cells ◽  
Complex Iii ◽  
Ros Production ◽  
Caspase 9 ◽  
Alveolar Epithelial

Asbestos causes pulmonary toxicity by mechanisms that in part involve reactive oxygen species (ROS). However, the precise source of ROS is unclear. We showed that asbestos induces alveolar epithelial cell (AEC) apoptosis by a mitochondrial-regulated death pathway. To determine whether mitochondrial-derived ROS are necessary for causing asbestos-induced AEC apoptosis, we utilized A549-ρο cells that lack mitochondrial DNA and a functional electron transport. As expected, antimycin, which induces an oxidative stress by blocking mitochondrial electron transport at complex III, increased dichlorofluoroscein (DCF) fluorescence in A549 cells but not in A549-ρο cells. Compared with A549 cells, ρο cells have less asbestos-induced ROS production, as assessed by DCF fluorescence, and reductions in total glutathione levels as well as less caspase-9 activation and apoptosis, as assessed by TdT-mediated dUTP nick end labeling staining and DNA fragmentation. A mitochondrial anion channel inhibitor that prevents ROS release from the mitochondria to the cytoplasm also blocked asbestos-induced A549 cell caspase-9 activation and apoptosis. Finally, a role for nonmitochondrial-derived ROS with exposure to high levels of asbestos (50 μg/cm2) was suggested by our findings that an iron chelator (phytic acid or deferoxamine) or a free radical scavenger (sodium benzoate) provided additional protection against asbestos-induced caspase-9 activation and DNA fragmentation in ρο cells. We conclude that asbestos fibers affect mitochondrial DNA and functional electron transport, resulting in mitochondrial-derived ROS production that in turn mediates AEC apoptosis. Nonmitochondrial-associated ROS may also contribute to AEC apoptosis, particularly with high levels of asbestos exposure.

Fibroblast Growth Factor-10 Attenuates H2O2-Induced Alveolar Epithelial Cell DNA Damage

2004 ◽  
Vol 31 (1) ◽  
pp. 107-113 ◽  
Author(s):  
Daya Upadhyay ◽  
Michael Bundesmann ◽  
Vijayalakshmi Panduri ◽  
Eduardo Correa-Meyer ◽  
David W. Kamp
Keyword(s):  
Dna Damage ◽  
Growth Factor ◽  
Epithelial Cell ◽  
Fibroblast Growth Factor ◽  
Alveolar Epithelial Cell ◽  
Fibroblast Growth ◽  
Alveolar Epithelial ◽  
Fibroblast Growth Factor 10

scholarly journals SIRT3 blocks myofibroblast differentiation and pulmonary fibrosis by preventing mitochondrial DNA damage

2017 ◽  
Vol 312 (1) ◽  
pp. L68-L78 ◽  
Author(s):  
Samik Bindu ◽  
Vinodkumar B. Pillai ◽  
Abhinav Kanwal ◽  
Sadhana Samant ◽  
Gökhan M. Mutlu ◽  
...  
Keyword(s):  
Dna Damage ◽  
Mitochondrial Dna ◽  
Pulmonary Fibrosis ◽  
Lung Fibrosis ◽  
Lung Fibroblasts ◽  
Whole Body ◽  
Myofibroblast Differentiation ◽  
Mitochondrial Dna Damage

Myofibroblast differentiation is a key process in the pathogenesis of fibrotic diseases. Transforming growth factor-β1 (TGF-β1) is a powerful inducer of myofibroblast differentiation and is implicated in pathogenesis of tissue fibrosis. This study was undertaken to determine the role of mitochondrial deacetylase SIRT3 in TGF-β1-induced myofibroblast differentiation in vitro and lung fibrosis in vivo. Treatment of human lung fibroblasts with TGF-β1 resulted in increased expression of fibrosis markers, smooth muscle α-actin (α-SMA), collagen-1, and fibronectin. TGF-β1 treatment also caused depletion of endogenous SIRT3, which paralleled with increased production of reactive oxygen species (ROS), DNA damage, and subsequent reduction in levels of 8-oxoguanine DNA glycosylase (OGG1), an enzyme that hydrolyzes oxidized guanine (8-oxo-dG) and thus protects DNA from oxidative damage. Overexpression of SIRT3 by adenovirus-mediated transduction reversed the effects of TGF-β1 on ROS production and mitochondrial DNA damage and inhibited TGF-β1-induced myofibroblast differentiation. To determine the antifibrotic role of SIRT3 in vivo, we used the bleomycin-induced mouse model of pulmonary fibrosis. Compared with wild-type controls, Sirt3-knockout mice showed exacerbated fibrosis after intratracheal instillation of bleomycin. Increased lung fibrosis was associated with decreased levels of OGG1 and concomitant accumulation of 8-oxo-dG and increased mitochondrial DNA damage. In contrast, the transgenic mice with whole body Sirt3 overexpression were protected from bleomycin-induced mtDNA damage and development of lung fibrosis. These data demonstrate a critical role of SIRT3 in the control of myofibroblast differentiation and lung fibrosis.

A cGAS-dependent response links DNA damage and senescence in alveolar epithelial cells: A potential drug target in IPF

2021 ◽  
Author(s):  
Michael Schuliga ◽  
Amama Kanwal ◽  
Jane Read ◽  
Kaj Erik Cornelis Blokland ◽  
Janette K. Burgess ◽  
...  
Keyword(s):  
Dna Damage ◽  
Epithelial Cell ◽  
Alveolar Epithelial Cell ◽  
Primary Cultures ◽  
Alveolar Epithelial Cells ◽  
Alveolar Epithelial ◽  
Sirna Knockdown ◽  
Interfering Rna ◽  
Culture Supernatants

Alveolar epithelial cell (AEC) senescence is implicated in the pathogenesis of idiopathic pulmonary fibrosis (IPF). Mitochondrial dysfunction including release of mitochondrial DNA (mtDNA) is a feature of senescence, which led us to investigate the role of the DNA-sensing GMP-AMP synthase (cGAS) in IPF, with a focus on AEC senescence. cGAS expression in fibrotic tissue from lungs of IPF patients was detected within cells immunoreactive for epithelial cell adhesion molecule (EpCAM) and p21, epithelial and senescence markers respectively. Submerged primary cultures of AECs isolated from lung tissue of IPF patients (IPF-AECs, n=5) exhibited higher baseline senescence than AECs from control donors (Ctrl-AECs, n=5-7), as assessed by increased nuclear histone 2AXγ phosphorylation, p21 mRNA and expression of senescence-associated secretory phenotype (SASP) cytokines. Pharmacological cGAS inhibition using RU.521 diminished IPF-AEC senescence in culture and attenuated induction of Ctrl-AEC senescence following etoposide-induced DNA damage. Short interfering RNA (siRNA) knockdown of cGAS also attenuated etoposide-induced senescence of the AEC line, A549. Higher levels of mtDNA were detected in the cytosol and culture supernatants of primary IPF- and etoposide-treated Ctrl-AECs when compared to Ctrl-AECs at baseline. Furthermore, ectopic mtDNA augmented cGAS-dependent senescence of Ctrl-AECs, whereas DNAse I treatment diminished IPF-AEC senescence. This study provides evidence that a self-DNA driven, cGAS-dependent response augments AEC senescence, identifying cGAS as a potential therapeutic target for IPF.

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