1
|
Zhong X, Deng Y, Yang H, Du X, Liu P, Du Y. Role of autophagy in skin photoaging: A narrative review. Medicine (Baltimore) 2024; 103:e37178. [PMID: 38394552 DOI: 10.1097/md.0000000000037178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/25/2024] Open
Abstract
As the largest organ of the human body, the skin serves as the primary barrier against external damage. The continuous increase in human activities and environmental pollution has resulted in the ongoing depletion of the ozone layer. Excessive exposure to ultraviolet (UV) radiation enhances the impact of external factors on the skin, leading to photoaging. Photoaging causes physical and psychological damage to the human body. The prevention and management of photoaging have attracted increased attention in recent years. Despite significant progress in understanding and mitigating UV-induced photoaging, the precise mechanisms through which autophagy contributes to the prevention of photoaging remain unclear. Given the important role of autophagy in repairing UV-induced DNA damage and scavenging oxidized lipids, autophagy is considered a novel strategy for preventing the occurrence of photoaging and other UV light-induced skin diseases. This review aims to elucidate the biochemical and clinical features of photoaging, the relationship of skin photoaging and chronological aging, the mechanisms underlying skin photoaging and autophagy, and the role of autophagy in skin photoaging.
Collapse
Affiliation(s)
- Xiaojiao Zhong
- Medical Cosmetic Center, The Affiliated Traditional Chinese Medicine Hospital, Southwest Medical University, Luzhou, China
| | | | | | | | | | | |
Collapse
|
2
|
Waneka G, Stewart J, Anderson JR, Li W, Wilusz J, Argueso JL, Sloan DB. UV damage induces production of mitochondrial DNA fragments with specific length profiles. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.07.566130. [PMID: 37986892 PMCID: PMC10659373 DOI: 10.1101/2023.11.07.566130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
UV light is a potent mutagen that induces bulky DNA damage in the form of cyclobutane pyrimidine dimers (CPDs). In eukaryotic cells, photodamage and other bulky lesions occurring in nuclear genomes (nucDNAs) can be repaired through nucleotide excision repair (NER), where dual incisions on both sides of a damaged site precede the removal of a single-stranded oligonucleotide containing the damage. Mitochondrial genomes (mtDNAs) are also susceptible to damage from UV light, but current views hold that the only way to eliminate bulky DNA damage in mtDNAs is through mtDNA degradation. Damage-containing oligonucleotides excised during NER can be captured with anti-damage antibodies and sequenced (XR-seq) to produce high resolution maps of active repair locations following UV exposure. We analyzed previously published datasets from Arabidopsis thaliana, Saccharomyces cerevisiae, and Drosophila melanogaster to identify reads originating from the mtDNA (and plastid genome in A. thaliana). In A. thaliana and S. cerevisiae, the mtDNA-mapping reads have unique length distributions compared to the nuclear-mapping reads. The dominant fragment size was 26 nt in S. cerevisiae and 28 nt in A. thaliana with distinct secondary peaks occurring in 2-nt (S. cerevisiae) or 4-nt (A. thaliana) intervals. These reads also show a nonrandom distribution of di-pyrimidines (the substrate for CPD formation) with TT enrichment at positions 7-8 of the reads. Therefore, UV damage to mtDNA appears to result in production of DNA fragments of characteristic lengths and positions relative to the damaged location. We hypothesize that these fragments may reflect the outcome of a previously uncharacterized mechanism of NER-like repair in mitochondria or a programmed mtDNA degradation pathway.
Collapse
Affiliation(s)
- Gus Waneka
- Department of Biology, Colorado State University, Fort Collins, Colorado, USA
| | - Joseph Stewart
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado, USA
| | - John R Anderson
- Department of Microbiology, Immunology & Pathology, Colorado State University, Fort Collins, Colorado, USA
| | - Wentao Li
- Department of Environmental Health Science, University of Georgia, Athens, Georgia, USA
| | - Jeffrey Wilusz
- Department of Microbiology, Immunology & Pathology, Colorado State University, Fort Collins, Colorado, USA
| | - Juan Lucas Argueso
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado, USA
| | - Daniel B Sloan
- Department of Biology, Colorado State University, Fort Collins, Colorado, USA
| |
Collapse
|
3
|
Wu AYT, Sekar P, Huang DY, Hsu SH, Chan CM, Lin WW. Spatiotemporal roles of AMPK in PARP-1- and autophagy-dependent retinal pigment epithelial cell death caused by UVA. J Biomed Sci 2023; 30:91. [PMID: 37936170 PMCID: PMC10629085 DOI: 10.1186/s12929-023-00978-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 09/29/2023] [Indexed: 11/10/2023] Open
Abstract
BACKGROUND Although stimulating autophagy caused by UV has been widely demonstrated in skin cells to exert cell protection, it remains unknown the cellular events in UVA-treated retinal pigment epithelial (RPE) cells. METHODS Human ARPE-19 cells were used to measure cell viability, mitochondrial reactive oxygen species (ROS), mitochondrial membrane potential (MMP), mitochondrial mass and lysosomal mass by flow cytometry. Mitochondrial oxygen consumption rate (OCR) was recorded using Seahorse XF flux analyzer. Confocal microscopic images were performed to indicate the mitochondrial dynamics, LC3 level, and AMPK translocation after UVA irradiation. RESULTS We confirmed mitochondrial ROS production and DNA damage are two major features caused by UVA. We found the cell death is prevented by autophagy inhibitor 3-methyladenine and gene silencing of ATG5, and UVA induces ROS-dependent LC3II expression, LC3 punctate and TFEB expression, suggesting the autophagic death in the UVA-stressed RPE cells. Although PARP-1 inhibitor olaparib increases DNA damage, ROS production, and cell death, it also blocks AMPK activation caused by UVA. Interestingly we found a dramatic nuclear export of AMPK upon UVA irradiation which is blocked by N-acetylcysteine and olaparib. In addition, UVA exposure gradually decreases lysosomal mass and inhibits cathepsin B activity at late phase due to lysosomal dysfunction. Nevertheless, cathepsin B inhibitor, CA-074Me, reverses the death extent, suggesting the contribution of cathepsin B in the death pathway. When examining the role of EGFR in cellular events caused by UVA, we found that UVA can rapidly transactivate EGFR, and treatment with EGFR TKIs (gefitinib and afatinib) enhances the cell death accompanied by the increased LC3II formation, ROS production, loss of MMP and mass of mitochondria and lysosomes. Although AMPK activation by ROS-PARP-1 mediates autophagic cell death, we surprisingly found that pretreatment of cells with AMPK activators (A769662 and metformin) reverses cell death. Concomitantly, both agents block UVA-induced mitochondrial ROS production, autophagic flux, and mitochondrial fission without changing the inhibition of cathepsin B. CONCLUSION UVA exposure rapidly induces ROS-PARP-1-AMPK-autophagic flux and late lysosomal dysfunction. Pre-inducing AMPK activation can prevent cellular events caused by UVA and provide a new protective strategy in photo-oxidative stress and photo-retinopathy.
Collapse
Affiliation(s)
- Anthony Yan-Tang Wu
- Department of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan
- Chemical Biology and Molecular Biophysics Program, Taiwan International Graduate Program, Academia Sinica, Taipei, Taiwan
| | - Ponarulselvam Sekar
- Department of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan
- Graduate Institute of Medical Sciences, Taipei Medical University, Taipei, Taiwan
| | - Duen-Yi Huang
- Department of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Shu-Hao Hsu
- Department of Ophthalmology, Cardinal Tien Hospital, New Taipei City, Taiwan
| | - Chi-Ming Chan
- Department of Ophthalmology, Cardinal Tien Hospital, New Taipei City, Taiwan.
- School of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan.
| | - Wan-Wan Lin
- Department of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan.
- Chemical Biology and Molecular Biophysics Program, Taiwan International Graduate Program, Academia Sinica, Taipei, Taiwan.
- Graduate Institute of Medical Sciences, Taipei Medical University, Taipei, Taiwan.
| |
Collapse
|
4
|
Kozal JS, Jayasundara N, Massarsky A, Lindberg CD, Oliveri AN, Cooper EM, Levin ED, Meyer JN, Giulio RTD. Mitochondrial dysfunction and oxidative stress contribute to cross-generational toxicity of benzo(a)pyrene in Danio rerio. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2023; 263:106658. [PMID: 37722151 PMCID: PMC10591944 DOI: 10.1016/j.aquatox.2023.106658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 08/06/2023] [Accepted: 08/10/2023] [Indexed: 09/20/2023]
Abstract
The potential for polycyclic aromatic hydrocarbons (PAHs) to have adverse effects that persist across generations is an emerging concern for human and wildlife health. This study evaluated the role of mitochondria, which are maternally inherited, in the cross-generational toxicity of benzo(a)pyrene (BaP), a model PAH and known mitochondrial toxicant. Mature female zebrafish (F0) were fed diets containing 0, 12.5, 125, or 1250 μg BaP/g at a feed rate of 1% body weight twice/day for 21 days. These females were bred with unexposed males, and the embryos (F1) were collected for subsequent analyses. Maternally-exposed embryos exhibited altered mitochondrial function and metabolic partitioning (i.e. the portion of respiration attributable to different cellular processes), as evidenced by in vivo oxygen consumption rates (OCRs). F1 embryos had lower basal and mitochondrial respiration and ATP turnover-mediated OCR, and increased proton leak and reserve capacity. Reductions in mitochondrial DNA (mtDNA) copy number, increases in mtDNA damage, and alterations in biomarkers of oxidative stress were also found in maternally-exposed embryos. Notably, the mitochondrial effects in offspring occurred largely in the absence of effects in maternal ovaries, suggesting that PAH-induced mitochondrial dysfunction may manifest in subsequent generations. Maternally-exposed larvae also displayed swimming hypoactivity. The lowest observed effect level (LOEL) for maternal BaP exposure causing mitochondrial effects in offspring was 12.5 µg BaP/g diet (nominally equivalent to 250 ng BaP/g fish). It was concluded that maternal BaP exposure can cause significant mitochondrial impairments in offspring.
Collapse
Affiliation(s)
- Jordan S Kozal
- Nicholas School of the Environment, Duke University, Durham, NC, USA.
| | | | - Andrey Massarsky
- Nicholas School of the Environment, Duke University, Durham, NC, USA
| | - Casey D Lindberg
- Nicholas School of the Environment, Duke University, Durham, NC, USA
| | - Anthony N Oliveri
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA
| | - Ellen M Cooper
- Nicholas School of the Environment, Duke University, Durham, NC, USA
| | - Edward D Levin
- Nicholas School of the Environment, Duke University, Durham, NC, USA; Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, NC, USA; Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, USA
| | - Joel N Meyer
- Nicholas School of the Environment, Duke University, Durham, NC, USA
| | | |
Collapse
|
5
|
Bahamondes Lorca VA, Wu S. Ultraviolet Light, Unfolded Protein Response and Autophagy †. Photochem Photobiol 2023; 99:498-508. [PMID: 36591940 DOI: 10.1111/php.13777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 12/22/2022] [Indexed: 01/03/2023]
Abstract
The endoplasmic reticulum (ER) plays an important role in the regulation of protein synthesis. Alterations in the folding capacity of the ER induce stress, which activates three ER sensors that mediate the unfolded protein response (UPR). Components of the pathways regulated by these sensors have been shown to regulate autophagy. The last corresponds to a mechanism of self-eating and recycling important for proper cell maintenance. Ultraviolet radiation (UV) is an external damaging stimulus that is known for inducing oxidative stress, and DNA, lipid and protein damage. Many controversies exist regarding the role of UV-inducing ER stress or autophagy. However, a connection between the three of them has not been addressed. In this review, we will discuss the contradictory theories regarding the relationships between UV radiation with the induction of ER stress and autophagy, as well as hypothetic connections between UV, ER stress and autophagy.
Collapse
Affiliation(s)
- Verónica A Bahamondes Lorca
- Edison Biotechnology Institute, Ohio University, Athens, OH.,Departamento de Tecnología Médica, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Shiyong Wu
- Edison Biotechnology Institute, Ohio University, Athens, OH.,Department of Chemistry and Biochemistry, Ohio University, Athens, OH
| |
Collapse
|
6
|
Park J, Baruch-Torres N, Iwai S, Herrmann GK, Brieba LG, Yin YW. Human Mitochondrial DNA Polymerase Metal Dependent UV Lesion Bypassing Ability. Front Mol Biosci 2022; 9:808036. [PMID: 35355510 PMCID: PMC8959595 DOI: 10.3389/fmolb.2022.808036] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 01/11/2022] [Indexed: 12/11/2022] Open
Abstract
Human mitochondrial DNA contains more UV-induced lesions than the nuclear DNA due to lack of mechanism to remove bulky photoproducts. Human DNA polymerase gamma (Pol γ) is the sole DNA replicase in mitochondria, which contains a polymerase (pol) and an exonuclease (exo) active site. Previous studies showed that Pol γ only displays UV lesion bypassing when its exonuclease activity is obliterated. To investigate the reaction environment on Pol γ translesion activity, we tested Pol γ DNA activity in the presence of different metal ions. While Pol γ is unable to replicate through UV lesions on DNA templates in the presence of Mg2+, it exhibits robust translesion DNA synthesis (TLS) on cyclobutane pyrimidine dimer (CPD)-containing template when Mg2+ was mixed with or completely replaced by Mn2+. Under these conditions, the efficiency of Pol γ′s TLS opposite CPD is near to that on a non-damaged template and is 800-fold higher than that of exonuclease-deficient Pol γ. Interestingly, Pol γ exhibits higher exonuclease activity in the presence of Mn2+ than with Mg2+, suggesting Mn2+-stimulated Pol γ TLS is not via suppressing its exonuclease activity. We suggest that Mn2+ ion expands Pol γ′s pol active site relative to Mg2+ so that a UV lesion can be accommodated and blocks the communication between pol and exo active sites to execute translesion DNA synthesis.
Collapse
Affiliation(s)
- Joon Park
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, United States
- Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, United States
| | - Noe Baruch-Torres
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Irapuato, Mexico
| | - Shigenori Iwai
- Division of Chemistry, Graduate School of Engineering Science, Osaka University, Toyonaka, Japan
| | - Geoffrey K. Herrmann
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, United States
- Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, United States
| | - Luis G. Brieba
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Irapuato, Mexico
- *Correspondence: Luis G. Brieba, ; Y. Whitney Yin,
| | - Y. Whitney Yin
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, United States
- Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, United States
- *Correspondence: Luis G. Brieba, ; Y. Whitney Yin,
| |
Collapse
|
7
|
Hershberger KA, Rooney JP, Turner EA, Donoghue LJ, Bodhicharla R, Maurer LL, Ryde IT, Kim JJ, Joglekar R, Hibshman JD, Smith LL, Bhatt DP, Ilkayeva OR, Hirschey MD, Meyer JN. Early-life mitochondrial DNA damage results in lifelong deficits in energy production mediated by redox signaling in Caenorhabditis elegans. Redox Biol 2021; 43:102000. [PMID: 33993056 PMCID: PMC8134077 DOI: 10.1016/j.redox.2021.102000] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 04/19/2021] [Accepted: 04/28/2021] [Indexed: 11/12/2022] Open
Abstract
The consequences of damage to the mitochondrial genome (mtDNA) are poorly understood, although mtDNA is more susceptible to damage resulting from some genotoxicants than nuclear DNA (nucDNA), and many environmental toxicants target the mitochondria. Reports from the toxicological literature suggest that exposure to early-life mitochondrial damage could lead to deleterious consequences later in life (the “Developmental Origins of Health and Disease” paradigm), but reports from other fields often report beneficial (“mitohormetic”) responses to such damage. Here, we tested the effects of low (causing no change in lifespan) levels of ultraviolet C (UVC)-induced, irreparable mtDNA damage during early development in Caenorhabditis elegans. This exposure led to life-long reductions in mtDNA copy number and steady-state ATP levels, accompanied by increased oxygen consumption and altered metabolite profiles, suggesting inefficient mitochondrial function. Exposed nematodes were also developmentally delayed, reached smaller adult size, and were rendered more susceptible to subsequent exposure to chemical mitotoxicants. Metabolomic and genetic analysis of key signaling and metabolic pathways supported redox and mitochondrial stress-response signaling during early development as a mechanism for establishing these persistent alterations. Our results highlight the importance of early-life exposures to environmental pollutants, especially in the context of exposure to chemicals that target mitochondria. Early life mtDNA damage led to lifelong deficits in mitochondrial function. C. elegans developed slowly and were sensitive to chemical exposures as adults. Redox signaling is a mechanism that establishes these persistent alterations. Data are consistent with the Developmental Origins of Health and Disease model.
Collapse
Affiliation(s)
- Kathleen A Hershberger
- Duke University, Nicholas School of the Environment, Integrated Toxicology and Environmental Health Program, Durham, NC, USA
| | - John P Rooney
- Duke University, Nicholas School of the Environment, Integrated Toxicology and Environmental Health Program, Durham, NC, USA
| | - Elena A Turner
- Duke University, Nicholas School of the Environment, Integrated Toxicology and Environmental Health Program, Durham, NC, USA
| | - Lauren J Donoghue
- Duke University, Nicholas School of the Environment, Integrated Toxicology and Environmental Health Program, Durham, NC, USA
| | - Rakesh Bodhicharla
- Duke University, Nicholas School of the Environment, Integrated Toxicology and Environmental Health Program, Durham, NC, USA
| | - Laura L Maurer
- Duke University, Nicholas School of the Environment, Integrated Toxicology and Environmental Health Program, Durham, NC, USA
| | - Ian T Ryde
- Duke University, Nicholas School of the Environment, Integrated Toxicology and Environmental Health Program, Durham, NC, USA
| | - Jina J Kim
- Duke University, Nicholas School of the Environment, Integrated Toxicology and Environmental Health Program, Durham, NC, USA
| | - Rashmi Joglekar
- Duke University, Nicholas School of the Environment, Integrated Toxicology and Environmental Health Program, Durham, NC, USA
| | - Jonathan D Hibshman
- Duke University Department of Biology and University Program in Genetics and Genomics, Durham, NC, USA
| | - Latasha L Smith
- Duke University, Nicholas School of the Environment, Integrated Toxicology and Environmental Health Program, Durham, NC, USA
| | | | | | | | - Joel N Meyer
- Duke University, Nicholas School of the Environment, Integrated Toxicology and Environmental Health Program, Durham, NC, USA.
| |
Collapse
|
8
|
Shu L, Hu C, Xu M, Yu J, He H, Lin J, Sha H, Lu B, Engelender S, Guan M, Song Z. ATAD3B is a mitophagy receptor mediating clearance of oxidative stress-induced damaged mitochondrial DNA. EMBO J 2021; 40:e106283. [PMID: 33665835 PMCID: PMC8047441 DOI: 10.15252/embj.2020106283] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 01/22/2021] [Accepted: 02/01/2021] [Indexed: 12/11/2022] Open
Abstract
Mitochondrial DNA (mtDNA) encodes several key components of respiratory chain complexes that produce cellular energy through oxidative phosphorylation. mtDNA is vulnerable to damage under various physiological stresses, especially oxidative stress. mtDNA damage leads to mitochondrial dysfunction, and dysfunctional mitochondria can be removed by mitophagy, an essential process in cellular homeostasis. However, how damaged mtDNA is selectively cleared from the cell, and how damaged mtDNA triggers mitophagy, remain mostly unknown. Here, we identified a novel mitophagy receptor, ATAD3B, which is specifically expressed in primates. ATAD3B contains a LIR motif that binds to LC3 and promotes oxidative stress-induced mitophagy in a PINK1-independent manner, thus promoting the clearance of damaged mtDNA induced by oxidative stress. Under normal conditions, ATAD3B hetero-oligomerizes with ATAD3A, thus promoting the targeting of the C-terminal region of ATAD3B to the mitochondrial intermembrane space. Oxidative stress-induced mtDNA damage or mtDNA depletion reduces ATAD3B-ATAD3A hetero-oligomerization and leads to exposure of the ATAD3B C-terminus at the mitochondrial outer membrane and subsequent recruitment of LC3 for initiating mitophagy. Furthermore, ATAD3B is little expressed in m.3243A > G mutated cells and MELAS patient fibroblasts showing endogenous oxidative stress, and ATAD3B re-expression promotes the clearance of m.3243A > G mutated mtDNA. Our findings uncover a new pathway to selectively remove damaged mtDNA and reveal that increasing ATAD3B activity is a potential therapeutic approach for mitochondrial diseases.
Collapse
Affiliation(s)
- Li Shu
- Hubei Key Laboratory of Cell HomeostasisCollege of Life SciencesFrontier Science Center for Immunology and MetabolismWuhan UniversityWuhanChina
| | - Chao Hu
- Hubei Key Laboratory of Cell HomeostasisCollege of Life SciencesFrontier Science Center for Immunology and MetabolismWuhan UniversityWuhanChina
| | - Meng Xu
- Hubei Key Laboratory of Cell HomeostasisCollege of Life SciencesFrontier Science Center for Immunology and MetabolismWuhan UniversityWuhanChina
| | - Jianglong Yu
- Hubei Key Laboratory of Cell HomeostasisCollege of Life SciencesFrontier Science Center for Immunology and MetabolismWuhan UniversityWuhanChina
| | - He He
- Hubei Key Laboratory of Cell HomeostasisCollege of Life SciencesFrontier Science Center for Immunology and MetabolismWuhan UniversityWuhanChina
| | - Jie Lin
- Department of NeurologyHuashan HospitalFudan UniversityShanghaiChina
| | - Hongying Sha
- State Key Laboratory of Medical NeurobiologyInstitute of Brain ScienceShanghai Medical CollegeFudan UniversityShanghaiChina
| | - Bin Lu
- Attardi Institute of Mitochondrial BiomedicineSchool of Life SciencesWenzhou Medical UniversityWenzhouChina
| | - Simone Engelender
- Department of BiochemistryRappaport Faculty of MedicineTechnion‐Israel Institute of TechnologyHaifaIsrael
| | - Minxin Guan
- Institute of GeneticsZhejiang University School of MedicineHangzhouChina
| | - Zhiyin Song
- Hubei Key Laboratory of Cell HomeostasisCollege of Life SciencesFrontier Science Center for Immunology and MetabolismWuhan UniversityWuhanChina
| |
Collapse
|
9
|
Zhao L, Sumberaz P. Mitochondrial DNA Damage: Prevalence, Biological Consequence, and Emerging Pathways. Chem Res Toxicol 2020; 33:2491-2502. [PMID: 32486637 DOI: 10.1021/acs.chemrestox.0c00083] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mitochondria have a plethora of functions within a eukaryotic cell, ranging from energy production, cell signaling, and protein cofactor synthesis to various aspects of metabolism. Mitochondrial dysfunction is known to cause over 200 named disorders and has been implicated in many human diseases and aging. Mitochondria have their own genetic material, mitochondrial DNA (mtDNA), which encodes 13 protein subunits in the oxidative phosphorylation system and a full set of transfer and rRNAs. Although more than 99% of the proteins in mitochondria are nuclear DNA (nDNA)-encoded, the integrity of mtDNA is critical for mitochondrial functions, as evidenced by mitochondrial diseases sourced from mtDNA mutations and depletions and the vital role of fragmented mtDNA molecules in cell signaling pathways. Previous research has shown that mtDNA is an important target of genotoxic assaults by a variety of chemical and physical factors. This Perspective discusses the prevalence of mtDNA damage by comparing the abundance of lesions in mDNA and nDNA and summarizes current knowledge on the biological pathways to cope with mtDNA damage, including mtDNA repair, mtDNA degradation, and mitochondrial fission and fusion. Also, emerging roles of mtDNA damage in mutagenesis and immune responses are reviewed.
Collapse
Affiliation(s)
- Linlin Zhao
- Department of Chemistry and Environmental Toxicology Graduate Program, University of California, Riverside, Riverside, California 92521, United States
| | - Philip Sumberaz
- Department of Chemistry and Environmental Toxicology Graduate Program, University of California, Riverside, Riverside, California 92521, United States
| |
Collapse
|
10
|
Babbar M, Basu S, Yang B, Croteau DL, Bohr VA. Mitophagy and DNA damage signaling in human aging. Mech Ageing Dev 2020; 186:111207. [PMID: 31923475 DOI: 10.1016/j.mad.2020.111207] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 01/02/2020] [Accepted: 01/03/2020] [Indexed: 12/27/2022]
Abstract
Aging is associated with multiple human pathologies. In the past few years mitochondrial homeostasis has been well correlated with age-related disorders and longevity. Mitochondrial homeostasis involves generation, biogenesis and removal of dysfunctional mitochondria via mitophagy. Mitophagy is regulated by various mitochondrial and extra-mitochondrial factors including morphology, oxidative stress and DNA damage. For decades, DNA damage and inefficient DNA repair have been considered as major determinants for age-related disorders. Although defects in DNA damage recognition and repair and mitophagy are well documented to be major factors in age-associated diseases, interactivity between these is poorly understood. Mitophagy efficiency decreases with age leading to accumulation of dysfunctional mitochondria enhancing the severity of age-related disorders including neurodegenerative diseases, inflammatory diseases, cancer, diabetes and many more. Therefore, mitophagy is being targeted for intervention in age-associated disorders. NAD+ supplementation has emerged as one intervention to target both defective DNA repair and mitophagy. In this review, we discuss the molecular signaling pathways involved in regulation of DNA damage and repair and of mitophagy, and we highlight the opportunities for clinical interventions targeting these processes to improve the quality of life during aging.
Collapse
Affiliation(s)
- Mansi Babbar
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Sambuddha Basu
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Beimeng Yang
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Deborah L Croteau
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Vilhelm A Bohr
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA.
| |
Collapse
|
11
|
Autophagy: Multiple Mechanisms to Protect Skin from Ultraviolet Radiation-Driven Photoaging. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2019; 2019:8135985. [PMID: 31915514 PMCID: PMC6930764 DOI: 10.1155/2019/8135985] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 11/26/2019] [Indexed: 01/07/2023]
Abstract
Autophagy is an essential cellular process that maintains balanced cell life. Restriction in autophagy may induce degenerative changes in humans. Natural or pathological aging of susceptible tissues has been linked with reduced autophagic activity. Skin photoaging is an example of such pathological condition caused by ambient solar UV radiation exposure. The UV-induced production of reaction oxygen species (ROS) has been linked to the promotion and progression of the photoaging process in exposed tissues. Accordingly, it has been suggested that autophagy is capable of delaying the skin photoaging process caused by solar ultraviolet (UV), although the underlying mechanism is still under debate. This review highlights several plausible mechanisms by which UV-induced ROS activates the cellular signaling pathways and modulates the autophagy. More specifically, the UV-mediated regulation of autophagy and age-related transcription factors is discussed to pinpoint the contribution of autophagy to antiphotoaging effects in the skin. The outcome of this review will provide insights into design intervention strategies for delaying the phenomenon of sunlight-induced photodamage, photoaging, and other aging-related chronic diseases based on factors that activate the autophagy process in the skin.
Collapse
|
12
|
Telomerase Impinges on the Cellular Response to Oxidative Stress Through Mitochondrial ROS-Mediated Regulation of Autophagy. Int J Mol Sci 2019; 20:ijms20061509. [PMID: 30917518 PMCID: PMC6470917 DOI: 10.3390/ijms20061509] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 03/15/2019] [Accepted: 03/15/2019] [Indexed: 12/30/2022] Open
Abstract
Telomerase has cellular functions beyond telomere stabilization, including a role in mitochondria. The function of the catalytic component—TERT—in mitochondria is still unknown, but it seems to play a role in the response to oxidative stress. Here, we interrogated the role of the subcellular localization of TERT to the response to hydrogen peroxide (H2O2) treatment. Using normal human fibroblasts (NHF) expressing non-tagged wild type (WT) human TERT (hTERT) or nuclear localization and function (nuchTERT), a mutant that we previously described as being competent in telomere elongation, while not being able to localize to mitochondria, we found the differential activation of autophagy as a function of hTERT’s subcellular localization. Specifically, we found that only cells expressing the mutant had significant increases in autophagy markers as a response to H2O2 challenge. Either the reintroduction of the mitochondrial pool of hTERT or the expression of mitochondrially-targeted catalase in mutant cells blunted the autophagic response under oxidative stress. Interestingly, autophagy activation was also associated with decreased levels of mitochondrial DNA damage. Taken together, these results suggest that the loss of hTERT in mitochondria initiates a signaling cascade that allows for cells to adapt to and cope with the lack of mitochondrial telomerase. Such effects also influence the cellular response to oxidative damage.
Collapse
|
13
|
Pan Q, Chen J, Guo L, Lu X, Liao S, Zhao C, Wang S, Liu H. Mechanistic insights into environmental and genetic risk factors for systemic lupus erythematosus. Am J Transl Res 2019; 11:1241-1254. [PMID: 30972159 PMCID: PMC6456562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 01/10/2019] [Indexed: 06/09/2023]
Abstract
Systemic lupus erythematosus (SLE) is an autoimmune disease involving multiple organ systems with diverse presentation, primarily affecting women of reproductive age. Various genetic and environmental risk factors are involved in the pathogenesis of SLE, and many SLE susceptibility genes have been identified recently; however, gene therapy is not a viable clinical option at this time. Thus, environmental risks factors, particularly regional characteristics that can be controlled, need to be further investigated. Here, we systematically explored these risk factors, including ultraviolet radiation, seasonal distribution, geographical distribution, and climate factors, and also summarized the mechanisms related to these risk factors. Probable mechanisms were explicated in at least four aspects including inflammatory mediators, apoptosis and autophagy in keratinocytes, epigenetic factors, and gene-environment interactions. This information is expected to provide practical insights into these risk factors in order to benefit patients with SLE and facilitate the development of potential therapeutic strategies.
Collapse
Affiliation(s)
- Qingjun Pan
- Key Laboratory of Prevention and Management of Chronic Kidney Disease of Zhanjiang City, Institute of Nephrology, Affiliated Hospital of Guangdong Medical UniversityZhanjiang 524001, Guangdong, China
| | - Jinxia Chen
- Key Laboratory of Prevention and Management of Chronic Kidney Disease of Zhanjiang City, Institute of Nephrology, Affiliated Hospital of Guangdong Medical UniversityZhanjiang 524001, Guangdong, China
| | - Linjie Guo
- Key Laboratory of Prevention and Management of Chronic Kidney Disease of Zhanjiang City, Institute of Nephrology, Affiliated Hospital of Guangdong Medical UniversityZhanjiang 524001, Guangdong, China
- Division of Rheumatology, Huizhou Central People’s HospitalHuizhou 516001, China
| | - Xing Lu
- Key Laboratory of Prevention and Management of Chronic Kidney Disease of Zhanjiang City, Institute of Nephrology, Affiliated Hospital of Guangdong Medical UniversityZhanjiang 524001, Guangdong, China
| | - Shuzhen Liao
- Key Laboratory of Prevention and Management of Chronic Kidney Disease of Zhanjiang City, Institute of Nephrology, Affiliated Hospital of Guangdong Medical UniversityZhanjiang 524001, Guangdong, China
| | - Chunfei Zhao
- Key Laboratory of Prevention and Management of Chronic Kidney Disease of Zhanjiang City, Institute of Nephrology, Affiliated Hospital of Guangdong Medical UniversityZhanjiang 524001, Guangdong, China
| | - Sijie Wang
- Key Laboratory of Prevention and Management of Chronic Kidney Disease of Zhanjiang City, Institute of Nephrology, Affiliated Hospital of Guangdong Medical UniversityZhanjiang 524001, Guangdong, China
| | - Huafeng Liu
- Key Laboratory of Prevention and Management of Chronic Kidney Disease of Zhanjiang City, Institute of Nephrology, Affiliated Hospital of Guangdong Medical UniversityZhanjiang 524001, Guangdong, China
| |
Collapse
|
14
|
Berky AJ, Ryde IT, Feingold B, Ortiz EJ, Wyatt LH, Weinhouse C, Hsu-Kim H, Meyer JN, Pan WK. Predictors of mitochondrial DNA copy number and damage in a mercury-exposed rural Peruvian population near artisanal and small-scale gold mining: An exploratory study. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2019; 60:197-210. [PMID: 30289587 PMCID: PMC6452630 DOI: 10.1002/em.22244] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 07/22/2018] [Accepted: 07/31/2018] [Indexed: 05/22/2023]
Abstract
Mitochondrial DNA (mtDNA) copy number (CN) and damage in circulating white blood cells have been proposed as effect biomarkers for pollutant exposures. Studies have shown that mercury accumulates in mitochondria and affects mitochondrial function and integrity; however, these data are derived largely from experiments in model systems, rather than human population studies that evaluate the potential utility of mitochondrial exposure biomarkers. We measured mtDNA CN and damage in white blood cells (WBCs) from 83 residents of nine communities in the Madre de Dios region of the Peruvian Amazon that vary in proximity to artisanal and small-scale gold mining. Prior research from this region reported high levels of mercury in fish and a significant association between food consumption and human total hair mercury level of residents. We observed that mtDNA CN and damage were both associated with consumption of fruit and vegetables, higher diversity of fruit consumed, residential location, and health characteristics, suggesting common environmental drivers. Surprisingly, we observed negative associations of mtDNA damage with both obesity and age. We did not observe any association between total hair mercury or, in contrast to previous results, age, with either mtDNA damage or CN. The results of this exploratory study highlight the importance of combining epidemiological and laboratory research in studying the effects of stressors on mitochondria, suggesting that future work should incorporate nutritional and social characteristics, and caution should be taken when applying conclusions from epidemiological studies conducted in the developed world to other regions, as results may not be easily translated. Environ. Mol. Mutagen. 60: 197-210, 2019. © 2018 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Axel J. Berky
- Nicholas School of the Environment, Box 90328, Duke University, Durham, NC 27708, USA
| | - Ian T. Ryde
- Nicholas School of the Environment, Box 90328, Duke University, Durham, NC 27708, USA
| | - Beth Feingold
- University of Albany, School of Public Health, Rensselaer, NY 12144, USA
| | - Ernesto J. Ortiz
- Duke Global Health Institute, Duke University, 310 Trent Dr, Durham, NC 27710, USA
| | - Lauren H. Wyatt
- Nicholas School of the Environment, Box 90328, Duke University, Durham, NC 27708, USA
| | - Caren Weinhouse
- Duke Global Health Institute, Duke University, 310 Trent Dr, Durham, NC 27710, USA
| | - Heileen Hsu-Kim
- Department of Civil and Engineering, Box 90287, Duke University, Durham, NC 27708, USA
| | - Joel N. Meyer
- Nicholas School of the Environment, Box 90328, Duke University, Durham, NC 27708, USA
- Corresponding authors: William Pan, Duke Global Health Institute, 310 Trent Drive, Campus Box 90519, Durham, NC 27708, fax 681-7748, , Joel N. Meyer, Nicholas School of the Environment, Box 90328, Duke University, Durham, NC 27708, USA,
| | - William K. Pan
- Nicholas School of the Environment, Box 90328, Duke University, Durham, NC 27708, USA
- Duke Global Health Institute, Duke University, 310 Trent Dr, Durham, NC 27710, USA
- Corresponding authors: William Pan, Duke Global Health Institute, 310 Trent Drive, Campus Box 90519, Durham, NC 27708, fax 681-7748, , Joel N. Meyer, Nicholas School of the Environment, Box 90328, Duke University, Durham, NC 27708, USA,
| |
Collapse
|
15
|
Zernii EY, Gancharova OS, Tiulina VV, Zamyatnin AA, Philippov PP, Baksheeva VE, Senin II. Mitochondria-targeted antioxidant SKQ1 protects cornea from oxidative damage induced by ultraviolet irradiation and mechanical injury. BMC Ophthalmol 2018; 18:336. [PMID: 30587174 PMCID: PMC6307206 DOI: 10.1186/s12886-018-0996-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 12/04/2018] [Indexed: 11/13/2022] Open
Abstract
Background Cornea protects the eye against natural and anthropogenic ultraviolet (UV) damage and mechanical injury. Corneal incisions produced by UV lasers in ophthalmic surgeries are often complicated by oxidative stress and inflammation, which delay wound healing and result in vision deterioration. This study trialed a novel approach to prevention and treatment of iatrogenic corneal injuries using SkQ1, a mitochondria-targeted antioxidant approved for therapy of polyethiological dry eye disease. Methods Rabbit models of UV-induced and mechanical corneal damage were employed. The animals were premedicated or treated with conjunctival instillations of 7.5 μM SkQ1. Corneal damage was assessed by fluorescein staining and histological analysis. Oxidative stress in cornea was monitored by measuring malondialdehyde (MDA) using thiobarbituric acid assay. Total antioxidant activity (AOA) was determined using hemoglobin/H2O2/luminol assay. Glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities were measured using colorimetric assays. Results In both models corneas exhibited fluorescein-stained lesions, histologically manifesting as basal membrane denudation, apoptosis of keratocytes, and stromal edema, which were accompanied by oxidative stress as indicated by increase in lipid peroxidation and decline in AOA. The UV-induced lesions were more severe and long healing as corneal endothelium was involved and GPx and SOD were downregulated. The treatment inhibited loss of keratocytes and other cells, facilitated re-epithelialization and stromal remodeling, and reduced inflammatory infiltrations and edema thereby accelerating corneal healing approximately 2-fold. Meanwhile the premedication almost completely prevented development of UV-induced lesions. Both therapies reduced oxidative stress, but only premedication inhibited downregulation of the innate antioxidant activity of the cornea. Conclusions SkQ1 efficiently prevents UV-induced corneal damage and enhances corneal wound healing after UV and mechanical impacts common to ocular surgery. Its therapeutic action can be attributed to suppression of mitochondrial oxidative stress, which in the first case embraces all corneal cells including epitheliocytes, while in the second case affects residual endothelial cells and stromal keratocytes actively working in wound healing. We suggest SkQ1 premedication to be used in ocular surgery for preventing iatrogenic complications in the cornea.
Collapse
Affiliation(s)
- Evgeni Yu Zernii
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia. .,Institute for Regenerative Medicine, Sechenov First Moscow State Medical University, Moscow, 119991, Russia.
| | - Olga S Gancharova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia.,Institute for Regenerative Medicine, Sechenov First Moscow State Medical University, Moscow, 119991, Russia
| | - Veronika V Tiulina
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia
| | - Andrey A Zamyatnin
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia.,Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Moscow, 119991, Russia
| | - Pavel P Philippov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia
| | - Viktoriia E Baksheeva
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia
| | - Ivan I Senin
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia.
| |
Collapse
|
16
|
Sample A, He YY. Autophagy in UV Damage Response. Photochem Photobiol 2017; 93:943-955. [PMID: 27935061 PMCID: PMC5466513 DOI: 10.1111/php.12691] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 10/22/2016] [Indexed: 12/14/2022]
Abstract
UV radiation exposure from sunlight and artificial tanning beds is the major risk factor for the development of skin cancer and skin photoaging. UV-induced skin damage can trigger a cascade of DNA damage response signaling pathways, including cell cycle arrest, DNA repair and, if damage is irreparable, apoptosis. Compensatory proliferation replaces the apoptotic cells to maintain skin barrier integrity. Disruption of these processes can be exploited to promote carcinogenesis by allowing the survival and proliferation of damaged cells. UV radiation also induces autophagy, a catabolic process that clears unwanted or damaged proteins, lipids and organelles. The mechanisms by which autophagy is activated following UV exposure, and the functions of autophagy in UV response, are only now being clarified. Here, we summarize the current understanding of the mechanisms governing autophagy regulation by UV, the roles of autophagy in regulating cellular response to UV-induced photodamage and the implications of autophagy modulation in the treatment and prevention of photoaging and skin cancer.
Collapse
Affiliation(s)
- Ashley Sample
- Department of Medicine, Section of Dermatology, University of Chicago, Chicago, IL
- Committee on Cancer Biology, University of Chicago, Chicago, IL
| | - Yu-Ying He
- Department of Medicine, Section of Dermatology, University of Chicago, Chicago, IL
- Committee on Cancer Biology, University of Chicago, Chicago, IL
| |
Collapse
|
17
|
Saki M, Prakash A. DNA damage related crosstalk between the nucleus and mitochondria. Free Radic Biol Med 2017; 107:216-227. [PMID: 27915046 PMCID: PMC5449269 DOI: 10.1016/j.freeradbiomed.2016.11.050] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 10/25/2016] [Accepted: 11/29/2016] [Indexed: 12/18/2022]
Abstract
The electron transport chain is the primary pathway by which a cell generates energy in the form of ATP. Byproducts of this process produce reactive oxygen species that can cause damage to mitochondrial DNA. If not properly repaired, the accumulation of DNA damage can lead to mitochondrial dysfunction linked to several human disorders including neurodegenerative diseases and cancer. Mitochondria are able to combat oxidative DNA damage via repair mechanisms that are analogous to those found in the nucleus. Of the repair pathways currently reported in the mitochondria, the base excision repair pathway is the most comprehensively described. Proteins that are involved with the maintenance of mtDNA are encoded by nuclear genes and translocate to the mitochondria making signaling between the nucleus and mitochondria imperative. In this review, we discuss the current understanding of mitochondrial DNA repair mechanisms and also highlight the sensors and signaling pathways that mediate crosstalk between the nucleus and mitochondria in the event of mitochondrial stress.
Collapse
Affiliation(s)
- Mohammad Saki
- Mitchell Cancer Institute, The University of South Alabama, 1660 Springhill Avenue, Mobile, AL 36604, United States
| | - Aishwarya Prakash
- Mitchell Cancer Institute, The University of South Alabama, 1660 Springhill Avenue, Mobile, AL 36604, United States.
| |
Collapse
|
18
|
Wyatt LH, Luz AL, Cao X, Maurer LL, Blawas AM, Aballay A, Pan WKY, Meyer JN. Effects of methyl and inorganic mercury exposure on genome homeostasis and mitochondrial function in Caenorhabditis elegans. DNA Repair (Amst) 2017; 52:31-48. [PMID: 28242054 PMCID: PMC5394729 DOI: 10.1016/j.dnarep.2017.02.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 12/05/2016] [Accepted: 02/06/2017] [Indexed: 12/21/2022]
Abstract
Mercury toxicity mechanisms have the potential to induce DNA damage and disrupt cellular processes, like mitochondrial function. Proper mitochondrial function is important for cellular bioenergetics and immune signaling and function. Reported impacts of mercury on the nuclear genome (nDNA) are conflicting and inconclusive, and mitochondrial DNA (mtDNA) impacts are relatively unknown. In this study, we assessed genotoxic (mtDNA and nDNA), metabolic, and innate immune impacts of inorganic and organic mercury exposure in Caenorhabditis elegans. Genotoxic outcomes measured included DNA damage, DNA damage repair (nucleotide excision repair, NER; base excision repair, BER), and genomic copy number following MeHg and HgCl2 exposure alone and in combination with known DNA damage-inducing agents ultraviolet C radiation (UVC) and hydrogen peroxide (H2O2), which cause bulky DNA lesions and oxidative DNA damage, respectively. Following exposure to both MeHg and HgCl2, low-level DNA damage (∼0.25 lesions/10kb mtDNA and nDNA) was observed. Unexpectedly, a higher MeHg concentration reduced damage in both genomes compared to controls. However, this observation was likely the result of developmental delay. In co-exposure treatments, both mercury compounds increased initial DNA damage (mtDNA and nDNA) in combination with H2O2 exposure, but had no impact in combination with UVC exposure. Mercury exposure both increased and decreased DNA damage removal via BER. DNA repair after H2O2 exposure in mercury-exposed nematodes resulted in damage levels lower than measured in controls. Impacts to NER were not detected. mtDNA copy number was significantly decreased in the MeHg-UVC and MeHg-H2O2 co-exposure treatments. Mercury exposure had metabolic impacts (steady-state ATP levels) that differed between the compounds; HgCl2 exposure decreased these levels, while MeHg slightly increased levels or had no impact. Both mercury species reduced mRNA levels for immune signaling-related genes, but had mild or no effects on survival on pathogenic bacteria. Overall, mercury exposure disrupted mitochondrial endpoints in a mercury-compound dependent fashion.
Collapse
Affiliation(s)
- Lauren H Wyatt
- Nicholas School of the Environment, Duke University, Durham, NC, United States.
| | - Anthony L Luz
- Nicholas School of the Environment, Duke University, Durham, NC, United States
| | - Xiou Cao
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, United States
| | - Laura L Maurer
- Nicholas School of the Environment, Duke University, Durham, NC, United States
| | - Ashley M Blawas
- Nicholas School of the Environment, Duke University, Durham, NC, United States
| | - Alejandro Aballay
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, United States
| | - William K Y Pan
- Nicholas School of the Environment, Duke University, Durham, NC, United States; Duke Global Health Institute, Duke University, Durham, NC, United States
| | - Joel N Meyer
- Nicholas School of the Environment, Duke University, Durham, NC, United States.
| |
Collapse
|
19
|
Evans SO, Jameson MB, Cursons RTM, Peters LM, Bird S, Jacobson GM. Development of a qPCR Method to Measure Mitochondrial and Genomic DNA Damage with Application to Chemotherapy-Induced DNA Damage and Cryopreserved Cells. BIOLOGY 2016; 5:biology5040039. [PMID: 27740596 PMCID: PMC5192419 DOI: 10.3390/biology5040039] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 09/27/2016] [Indexed: 11/23/2022]
Abstract
DNA damage quantitation assays such as the comet assay have focused on the measurement of total nuclear damage per cell. The adoption of PCR-based techniques to quantify DNA damage has enabled sequence- and organelle-specific assessment of DNA lesions. Here we report on an adaptation of a qPCR technique to assess DNA damage in nuclear and mitochondrial targets relative to control. Novel aspects of this assay include application of the assay to the Rotor-Gene platform with optimized DNA polymerase/fluorophore/primer set combination in a touchdown PCR protocol. Assay validation was performed using ultraviolet C radiation in A549 and THP1 cancer cell lines. A comparison was made to the comet assay applied to peripheral blood mononuclear cells, and an estimation of the effects of cryopreservation on ultraviolet C-induced DNA damage was carried out. Finally, dose responses for DNA damage were measured in peripheral blood mononuclear cells following exposure to the cytotoxic agents bleomycin and cisplatin. We show reproducible experimental outputs across the tested conditions and concordance with published findings with respect to mitochondrial and nuclear genotoxic susceptibilities. The application of this DNA damage assay to a wide range of clinical and laboratory-derived samples is both feasible and resource-efficient.
Collapse
Affiliation(s)
- Stephen O Evans
- Biomedical Research Unit, School of Science, University of Waikato Private Bag 3105, Hamilton 3240, New Zealand.
| | - Michael B Jameson
- Department of Oncology, Regional Cancer Centre, Waikato Hospital, Hamilton West 3204, New Zealand.
| | - Ray T M Cursons
- Biomedical Research Unit, School of Science, University of Waikato Private Bag 3105, Hamilton 3240, New Zealand.
| | - Linda M Peters
- Biomedical Research Unit, School of Science, University of Waikato Private Bag 3105, Hamilton 3240, New Zealand.
| | - Steve Bird
- Biomedical Research Unit, School of Science, University of Waikato Private Bag 3105, Hamilton 3240, New Zealand.
| | - Gregory M Jacobson
- Biomedical Research Unit, School of Science, University of Waikato Private Bag 3105, Hamilton 3240, New Zealand.
| |
Collapse
|
20
|
Ju YS. Intracellular mitochondrial DNA transfers to the nucleus in human cancer cells. Curr Opin Genet Dev 2016; 38:23-30. [PMID: 27010587 DOI: 10.1016/j.gde.2016.02.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2016] [Revised: 02/12/2016] [Accepted: 02/22/2016] [Indexed: 11/28/2022]
Abstract
Genome instability is a well-known hallmark of cancer cells. With the revolution of high-throughput sequencing technologies, our knowledge of somatically acquired genome structural variation (SV) has greatly improved over the last decade. Remarkably, surveys of thousands of human whole-cancer genomes have shown that chromosomal rearrangements are frequently combined with mitochondrial DNA (mtDNA) fragments somatically transferred to the nucleus. The high transfer rate and features of integration breakpoints provide clues for understanding the potential mechanisms underlying these events and provide insights into the role of mtDNA segments transferred into the nucleus. In this review, I discuss our current understanding of somatic nuclear transfer of mitochondrial DNA into the nuclear genome of human cancer cells.
Collapse
Affiliation(s)
- Young Seok Ju
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea.
| |
Collapse
|
21
|
Van Houten B, Hunter SE, Meyer JN. Mitochondrial DNA damage induced autophagy, cell death, and disease. Front Biosci (Landmark Ed) 2016; 21:42-54. [PMID: 26709760 DOI: 10.2741/4375] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Mammalian mitochondria contain multiple small genomes. While these organelles have efficient base excision removal of oxidative DNA lesions and alkylation damage, many DNA repair systems that work on nuclear DNA damage are not active in mitochondria. What is the fate of DNA damage in the mitochondria that cannot be repaired or that overwhelms the repair system? Some forms of mitochondrial DNA damage can apparently trigger mitochondrial DNA destruction, either via direct degradation or through specific forms of autophagy, such as mitophagy. However, accumulation of certain types of mitochondrial damage, in the absence of DNA ligase III (Lig3) or exonuclease G (EXOG), can directly trigger cell death. This review examines the cellular effects of persistent damage to mitochondrial genomes and discusses the very different cell fates that occur in response to different kinds of damage.
Collapse
Affiliation(s)
- Bennett Van Houten
- Department of Pharmacology Chemical Biology, University of Pittsburgh, 15213-1863,
| | - Senyene E Hunter
- School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27516
| | - Joel N Meyer
- Nicholas School of the Environment, Duke University, Durham, NC 27708-0328
| |
Collapse
|
22
|
Li R, Jen N, Wu L, Lee J, Fang K, Quigley K, Lee K, Wang S, Zhou B, Vergnes L, Chen YR, Li Z, Reue K, Ann DK, Hsiai TK. Disturbed Flow Induces Autophagy, but Impairs Autophagic Flux to Perturb Mitochondrial Homeostasis. Antioxid Redox Signal 2015; 23:1207-19. [PMID: 26120766 PMCID: PMC4657520 DOI: 10.1089/ars.2014.5896] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
AIM Temporal and spatial variations in shear stress are intimately linked with vascular metabolic effects. Autophagy is tightly regulated in intracellular bulk degradation/recycling system for maintaining cellular homeostasis. We postulated that disturbed flow modulates autophagy with an implication in mitochondrial superoxide (mtO2(•-)) production. RESULTS In the disturbed flow or oscillatory shear stress (OSS)-exposed aortic arch, we observed prominent staining of p62, a reverse marker of autophagic flux, whereas in the pulsatile shear stress (PSS)-exposed descending aorta, p62 was attenuated. OSS significantly increased (i) microtubule-associated protein light chain 3 (LC3) II to I ratios in human aortic endothelial cells, (ii) autophagosome formation as quantified by green fluorescent protein (GFP)-LC3 dots per cell, and (iii) p62 protein levels, whereas manganese superoxide dismutase (MnSOD) overexpression by recombinant adenovirus, N-acetyl cysteine treatment, or c-Jun N-terminal kinase (JNK) inhibition reduced OSS-mediated LC3-II/LC3-I ratios and mitochondrial DNA damage. Introducing bafilomycin to Earle's balanced salt solution or to OSS condition incrementally increased both LC3-II/LC3-I ratios and p62 levels, implicating impaired autophagic flux. In the OSS-exposed aortic arch, both anti-phospho-JNK and anti-8-hydroxy-2'-deoxyguanosine (8-OHdG) staining for DNA damage were prominent, whereas in the PSS-exposed descending aorta, the staining was nearly absent. Knockdown of ATG5 with siRNA increased OSS-mediated mtO2(•-), whereas starvation or rapamycin-induced autophagy reduced OSS-mediated mtO2(•-), mitochondrial respiration, and complex II activity. INNOVATION Disturbed flow-mediated oxidative stress and JNK activation induce autophagy. CONCLUSION OSS impairs autophagic flux to interfere with mitochondrial homeostasis. Antioxid. Redox Signal. 23, 1207-1219.
Collapse
Affiliation(s)
- Rongsong Li
- 1 Division of Cardiology, Department of Medicine, UCLA David Geffen School of Medicine , Los Angeles, California
| | - Nelson Jen
- 2 Department of Bioengineering, UCLA Henry Samueli School of Engineering and Applied Science , Los Angeles, California
| | - Lan Wu
- 1 Division of Cardiology, Department of Medicine, UCLA David Geffen School of Medicine , Los Angeles, California
| | - Juhyun Lee
- 2 Department of Bioengineering, UCLA Henry Samueli School of Engineering and Applied Science , Los Angeles, California
| | - Karen Fang
- 1 Division of Cardiology, Department of Medicine, UCLA David Geffen School of Medicine , Los Angeles, California
| | - Katherine Quigley
- 1 Division of Cardiology, Department of Medicine, UCLA David Geffen School of Medicine , Los Angeles, California
| | - Katherine Lee
- 1 Division of Cardiology, Department of Medicine, UCLA David Geffen School of Medicine , Los Angeles, California
| | - Sky Wang
- 1 Division of Cardiology, Department of Medicine, UCLA David Geffen School of Medicine , Los Angeles, California
| | - Bill Zhou
- 1 Division of Cardiology, Department of Medicine, UCLA David Geffen School of Medicine , Los Angeles, California
| | - Laurent Vergnes
- 3 Department of Human Genetics, UCLA David Geffen School of Medicine , Los Angeles, California
| | - Yun-Ru Chen
- 4 Department of Molecular Pharmacology, Beckman Research Institute, City of Hope National Medical Center , Duarte, California
| | - Zhaoping Li
- 5 Department of Medicine, VA Greater Los Angeles Healthcare System, UCLA David Geffen School of Medicine , Los Angeles, California
| | - Karen Reue
- 3 Department of Human Genetics, UCLA David Geffen School of Medicine , Los Angeles, California
| | - David K Ann
- 4 Department of Molecular Pharmacology, Beckman Research Institute, City of Hope National Medical Center , Duarte, California
| | - Tzung K Hsiai
- 1 Division of Cardiology, Department of Medicine, UCLA David Geffen School of Medicine , Los Angeles, California.,2 Department of Bioengineering, UCLA Henry Samueli School of Engineering and Applied Science , Los Angeles, California.,5 Department of Medicine, VA Greater Los Angeles Healthcare System, UCLA David Geffen School of Medicine , Los Angeles, California
| |
Collapse
|
23
|
Czarny P, Pawlowska E, Bialkowska-Warzecha J, Kaarniranta K, Blasiak J. Autophagy in DNA damage response. Int J Mol Sci 2015; 16:2641-62. [PMID: 25625517 PMCID: PMC4346856 DOI: 10.3390/ijms16022641] [Citation(s) in RCA: 107] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 01/12/2015] [Indexed: 12/15/2022] Open
Abstract
DNA damage response (DDR) involves DNA repair, cell cycle regulation and apoptosis, but autophagy is also suggested to play a role in DDR. Autophagy can be activated in response to DNA-damaging agents, but the exact mechanism underlying this activation is not fully understood, although it is suggested that it involves the inhibition of mammalian target of rapamycin complex 1 (mTORC1). mTORC1 represses autophagy via phosphorylation of the ULK1/2-Atg13-FIP200 complex thus preventing maturation of pre-autophagosomal structures. When DNA damage occurs, it is recognized by some proteins or their complexes, such as poly(ADP)ribose polymerase 1 (PARP-1), Mre11-Rad50-Nbs1 (MRN) complex or FOXO3, which activate repressors of mTORC1. SQSTM1/p62 is one of the proteins whose levels are regulated via autophagic degradation. Inhibition of autophagy by knockout of FIP200 results in upregulation of SQSTM1/p62, enhanced DNA damage and less efficient damage repair. Mitophagy, one form of autophagy involved in the selective degradation of mitochondria, may also play role in DDR. It degrades abnormal mitochondria and can either repress or activate apoptosis, but the exact mechanism remains unknown. There is a need to clarify the role of autophagy in DDR, as this process may possess several important biomedical applications, involving also cancer therapy.
Collapse
Affiliation(s)
- Piotr Czarny
- Department of Molecular Genetics, University of Lodz, Pomorska 141/143, 90-236 Lodz, Poland.
| | - Elzbieta Pawlowska
- Department of Orthodontics, Medical University of Lodz, Pomorska 251, 92-216 Lodz, Poland.
| | - Jolanta Bialkowska-Warzecha
- Department of Infectious and Liver Diseases, Medical University of Lodz, Kniaziewicza 1/5, 92-347 Lodz, Poland.
| | - Kai Kaarniranta
- Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, Kuopio FI-70211, Finland.
| | - Janusz Blasiak
- Department of Molecular Genetics, University of Lodz, Pomorska 141/143, 90-236 Lodz, Poland.
| |
Collapse
|
24
|
A rapid assay for measuring nucleotide excision repair by oligonucleotide retrieval. Sci Rep 2014; 4:4894. [PMID: 24809800 PMCID: PMC4013936 DOI: 10.1038/srep04894] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 04/17/2014] [Indexed: 01/03/2023] Open
Abstract
Nucleotide excision repair (NER) excises bulky DNA lesions induced by mutagens and carcinogens. The repair process includes recognition of DNA damage, excision of a short patch of nucleotides containing the damaged base, re-synthesis of a new DNA strand and ligation of the nicks to restore the sequence integrity. Mutation or aberrant transcription of NER genes reduces repair efficiency and results in the accumulation of mutations that is associated with the development of cancer. Here we present a rapid, sensitive and quantitative assay to measure NER activity in human cells, which we term the Oligonucleotide Retrieval Assay (ORA). We used oligonucleotide constructs containing the UV-damaged adduct, cyclobutane pyrimidine dimer (CPD), to transfect human cells, and retrieved the oligonucleotides for quantification of the repaired, CPD-free DNA by real-time quantitative PCR. We demonstrate that ORA can quantify the extent of NER in diverse cell types, including immortalized, primary and stem-like cells.
Collapse
|
25
|
Gebhard D, Matt K, Burger K, Bergemann J. Shortwave UV-Induced Damage as Part of the Solar Damage Spectrum Is Not a Major Contributor to Mitochondrial Dysfunction. J Biochem Mol Toxicol 2014; 28:256-62. [DOI: 10.1002/jbt.21561] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 02/07/2014] [Accepted: 02/11/2014] [Indexed: 01/22/2023]
Affiliation(s)
- Daniel Gebhard
- Department of Life Sciences; Albstadt-Sigmaringen University of Applied Sciences; 72488 Sigmaringen Germany
| | - Katja Matt
- Department of Life Sciences; Albstadt-Sigmaringen University of Applied Sciences; 72488 Sigmaringen Germany
| | - Katharina Burger
- Department of Life Sciences; Albstadt-Sigmaringen University of Applied Sciences; 72488 Sigmaringen Germany
| | - Jörg Bergemann
- Department of Life Sciences; Albstadt-Sigmaringen University of Applied Sciences; 72488 Sigmaringen Germany
| |
Collapse
|
26
|
Bess AS, Leung MCK, Ryde IT, Rooney JP, Hinton DE, Meyer JN. Effects of mutations in mitochondrial dynamics-related genes on the mitochondrial response to ultraviolet C radiation in developing Caenorhabditis elegans. WORM 2013; 2:e23763. [PMID: 24058863 PMCID: PMC3670464 DOI: 10.4161/worm.23763] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Accepted: 01/23/2013] [Indexed: 02/02/2023]
Abstract
We recently found that genes involved in mitochondrial dynamics and autophagy are required for removal of UVC-induced mitochondrial DNA damage. However, drp-1 and pink-1, unlike the autophagy and fusion genes tested, were not necessary for larval development after exposure. We hypothesized that increased fusion resulting from mutations in these genes facilitated recovery of mitochondrial function. In this work, we investigated this hypothesis by studying the effects of fis-1, fis-2, drp-1 and pink-1 mutations on mitochondrial responses to UVC exposure including ATP levels, mitochondrial DNA copy number, larval development and mitochondrial morphology. Our results suggest that mutations that promote highly networked mitochondria have the capacity to lessen the effects of mitochondrial genotoxicants on the function of this organelle.
Collapse
Affiliation(s)
- Amanda S Bess
- Nicholas School of the Environment; Duke University; Durham, NC USA
| | | | | | | | | | | |
Collapse
|
27
|
Meyer JN, Leung MCK, Rooney JP, Sendoel A, Hengartner MO, Kisby GE, Bess AS. Mitochondria as a target of environmental toxicants. Toxicol Sci 2013; 134:1-17. [PMID: 23629515 PMCID: PMC3693132 DOI: 10.1093/toxsci/kft102] [Citation(s) in RCA: 350] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Enormous strides have recently been made in our understanding of the biology and pathobiology of mitochondria. Many diseases have been identified as caused by mitochondrial dysfunction, and many pharmaceuticals have been identified as previously unrecognized mitochondrial toxicants. A much smaller but growing literature indicates that mitochondria are also targeted by environmental pollutants. We briefly review the importance of mitochondrial function and maintenance for health based on the genetics of mitochondrial diseases and the toxicities resulting from pharmaceutical exposure. We then discuss how the principles of mitochondrial vulnerability illustrated by those fields might apply to environmental contaminants, with particular attention to factors that may modulate vulnerability including genetic differences, epigenetic interactions, tissue characteristics, and developmental stage. Finally, we review the literature related to environmental mitochondrial toxicants, with a particular focus on those toxicants that target mitochondrial DNA. We conclude that the fields of environmental toxicology and environmental health should focus more strongly on mitochondria.
Collapse
Affiliation(s)
- Joel N Meyer
- Nicholas School of the Environment, Duke University, Durham, NC, USA.
| | | | | | | | | | | | | |
Collapse
|
28
|
Leung MCK, Rooney JP, Ryde IT, Bernal AJ, Bess AS, Crocker TL, Ji AQ, Meyer JN. Effects of early life exposure to ultraviolet C radiation on mitochondrial DNA content, transcription, ATP production, and oxygen consumption in developing Caenorhabditis elegans. BMC Pharmacol Toxicol 2013; 14:9. [PMID: 23374645 PMCID: PMC3621653 DOI: 10.1186/2050-6511-14-9] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Accepted: 01/14/2013] [Indexed: 11/25/2022] Open
Abstract
Background Mitochondrial DNA (mtDNA) is present in multiple copies per cell and undergoes dramatic amplification during development. The impacts of mtDNA damage incurred early in development are not well understood, especially in the case of types of mtDNA damage that are irreparable, such as ultraviolet C radiation (UVC)-induced photodimers. Methods We exposed first larval stage nematodes to UVC using a protocol that results in accumulated mtDNA damage but permits nuclear DNA (nDNA) repair. We then measured the transcriptional response, as well as oxygen consumption, ATP levels, and mtDNA copy number through adulthood. Results Although the mtDNA damage persisted to the fourth larval stage, we observed only a relatively minor ~40% decrease in mtDNA copy number. Transcriptomic analysis suggested an inhibition of aerobic metabolism and developmental processes; mRNA levels for mtDNA-encoded genes were reduced ~50% at 3 hours post-treatment, but recovered and, in some cases, were upregulated at 24 and 48 hours post-exposure. The mtDNA polymerase γ was also induced ~8-fold at 48 hours post-exposure. Moreover, ATP levels and oxygen consumption were reduced in response to UVC exposure, with marked reductions of ~50% at the later larval stages. Conclusions These results support the hypothesis that early life exposure to mitochondrial genotoxicants could result in mitochondrial dysfunction at later stages of life, thereby highlighting the potential health hazards of time-delayed effects of these genotoxicants in the environment.
Collapse
Affiliation(s)
- Maxwell C K Leung
- Nicholas School of the Environment, Duke University, Durham, NC, USA
| | | | | | | | | | | | | | | |
Collapse
|