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Ventayol-Guirado M, Hernandez-Rodriguez J, Florit J, Llull-Alberti MV, Barragan R, Ferragut JF, Martorell J, Heine-Suñer D, Martinez I, Picornell A, Torres-Juan L, Peralta L. First follicular fluid cf-mtDNA sequencing unveils ovarian stimulation-induced mutations impacting oocyte quality and IVF success. J Assist Reprod Genet 2025:10.1007/s10815-025-03511-8. [PMID: 40405035 DOI: 10.1007/s10815-025-03511-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2025] [Accepted: 05/05/2025] [Indexed: 05/24/2025] Open
Abstract
PURPOSE Cell-free mitochondrial DNA (cf-mtDNA) has emerged as a promising non-invasive method to predict embryo implantation potential. This study presents the first sequencing of cf-mtDNA in follicular fluid, aiming to explore the impact of ovarian stimulation treatment on the accumulation of mtDNA mutations and assess their implications for IVF outcomes. METHODS We selected 24 women aged 27 to 35 from the Assisted Reproduction Unit based on inclusion criteria requiring them to be undergoing their first IVF cycle without known infertility issues. For each participant, blood samples were collected prior to ovarian stimulation, and follicular fluid samples were obtained at the time of oocyte retrieval. Long-PCR amplification and next-generation sequencing were used to identify mtDNA mutations. RESULTS Ovarian stimulation-induced mtDNA mutations in follicular fluid were identified primarily in the D-loop region of the mitochondrial genome. These mutations were correlated with low oocyte counts and poor embryo quality, ultimately reducing IVF success rates. The accumulation of these mutations followed a time-dependent pattern, with longer stimulation durations resulting in higher mutation rates and lower pregnancy outcomes. Prolonged stimulations may exacerbate oxidative stress, negatively impacting oocyte quality. CONCLUSIONS By introducing the first sequencing of follicular fluid cf-mtDNA, this study establishes a direct link between ovarian stimulation-induced mtDNA mutations and reduced IVF efficacy, highlighting them as non-invasive biomarkers for predicting IVF outcomes. Future research may focus on optimizing stimulation protocols or incorporating antioxidants to minimize mtDNA mutations, improving oocyte quality and overall IVF success rates for patients.
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Affiliation(s)
- Marc Ventayol-Guirado
- Genomics of Health Research Group, Health Research Institute of the Balearic Islands (IdISBa), 07120, Palma, Balearic Islands, Spain.
| | - Jessica Hernandez-Rodriguez
- Genomics of Health Research Group, Health Research Institute of the Balearic Islands (IdISBa), 07120, Palma, Balearic Islands, Spain
- Molecular Diagnostics and Clinical Genetics Unit, Hospital Universitari Son Espases, 07120, Palma, Balearic Islands, Spain
| | - Joana Florit
- Genomics of Health Research Group, Health Research Institute of the Balearic Islands (IdISBa), 07120, Palma, Balearic Islands, Spain
| | - Maria Victoria Llull-Alberti
- Genomics of Health Research Group, Health Research Institute of the Balearic Islands (IdISBa), 07120, Palma, Balearic Islands, Spain
| | - Raquel Barragan
- Assisted Reproduction Unit, Hospital Universitari Son Espases, 07120, Palma, Balearic Islands, Spain
| | - Joana Francesca Ferragut
- Biology Department, Universitat de Les Illes Balears, 07122, Palma, Balearic Islands, Spain
- Institut Universitari d'Investigació en Ciències de La Salut (IUNICS), 07122, Palma, Balearic Islands, Spain
| | - Jaume Martorell
- Obstetrics and Gynecology Service, Hospital Universitari Son Espases, 07120, Palma, Balearic Islands, Spain
| | - Damian Heine-Suñer
- Genomics of Health Research Group, Health Research Institute of the Balearic Islands (IdISBa), 07120, Palma, Balearic Islands, Spain
- Molecular Diagnostics and Clinical Genetics Unit, Hospital Universitari Son Espases, 07120, Palma, Balearic Islands, Spain
| | - Iciar Martinez
- Genomics of Health Research Group, Health Research Institute of the Balearic Islands (IdISBa), 07120, Palma, Balearic Islands, Spain
- Molecular Diagnostics and Clinical Genetics Unit, Hospital Universitari Son Espases, 07120, Palma, Balearic Islands, Spain
| | - Antonia Picornell
- Biology Department, Universitat de Les Illes Balears, 07122, Palma, Balearic Islands, Spain
- Institut Universitari d'Investigació en Ciències de La Salut (IUNICS), 07122, Palma, Balearic Islands, Spain
| | - Laura Torres-Juan
- Genomics of Health Research Group, Health Research Institute of the Balearic Islands (IdISBa), 07120, Palma, Balearic Islands, Spain
- Molecular Diagnostics and Clinical Genetics Unit, Hospital Universitari Son Espases, 07120, Palma, Balearic Islands, Spain
| | - Laura Peralta
- Genomics of Health Research Group, Health Research Institute of the Balearic Islands (IdISBa), 07120, Palma, Balearic Islands, Spain
- Assisted Reproduction Unit, Hospital Universitari Son Espases, 07120, Palma, Balearic Islands, Spain
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Abu-Amero KK, Almadani B, Abualkhair S, Hameed S, Kondkar AA, Sollazzo A, Yu AC, Busin M, Zauli G. Mitochondrial DNA Pathogenic Variants in Ophthalmic Diseases: A Review. Genes (Basel) 2025; 16:347. [PMID: 40149498 PMCID: PMC11941924 DOI: 10.3390/genes16030347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2025] [Revised: 03/09/2025] [Accepted: 03/14/2025] [Indexed: 03/29/2025] Open
Abstract
Mitochondria are vital organelles responsible for ATP production and metabolic regulation, essential for energy-intensive cells such as retinal ganglion cells. Dysfunction in mitochondrial oxidative phosphorylation or mitochondrial DNA (mtDNA) pathogenic variants can disrupt ATP synthesis, cause oxidative stress, and lead to cell death. This has profound implications for tissues such as the retina, optic nerve, and retinal pigment epithelium, which are dependent on robust mitochondrial function. In this review, we provide a comprehensive compilation of pathogenic variants in the mtDNA associated with various ophthalmic diseases, including Leber's hereditary optic neuropathy, chronic progressive external ophthalmoplegia, Leigh syndrome, mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes, among others. We highlight the genetic variants implicated in these conditions, their pathogenic roles, and the phenotypic consequences of mitochondrial dysfunction in ocular tissues. In addition to well-established mutations, we also discuss the emerging evidence of the role of mtDNA's variants in complex multifactorial diseases, such as non-arteritic anterior ischemic optic neuropathy, primary open-angle glaucoma, and age-related macular degeneration. The review aims to serve as a valuable resource for clinicians and researchers, providing a detailed overview of mtDNA pathogenic variants and their clinical significance in the context of mitochondrial-related eye diseases.
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Affiliation(s)
- Khaled K. Abu-Amero
- Research Department, King Khaled Eye Specialist Hospital, Riyadh 11462, Saudi Arabia; (B.A.); (S.A.); (S.H.); (G.Z.)
| | - Bashaer Almadani
- Research Department, King Khaled Eye Specialist Hospital, Riyadh 11462, Saudi Arabia; (B.A.); (S.A.); (S.H.); (G.Z.)
| | - Shereen Abualkhair
- Research Department, King Khaled Eye Specialist Hospital, Riyadh 11462, Saudi Arabia; (B.A.); (S.A.); (S.H.); (G.Z.)
| | - Syed Hameed
- Research Department, King Khaled Eye Specialist Hospital, Riyadh 11462, Saudi Arabia; (B.A.); (S.A.); (S.H.); (G.Z.)
| | - Altaf A Kondkar
- Department of Ophthalmology, College of Medicine, King Saud University, Riyadh 11411, Saudi Arabia;
| | - Andrea Sollazzo
- Department of Translational Medicine, University of Ferrara, 44121 Ferrara, Italy; (A.S.); (A.C.Y.); (M.B.)
| | - Angeli Christy Yu
- Department of Translational Medicine, University of Ferrara, 44121 Ferrara, Italy; (A.S.); (A.C.Y.); (M.B.)
| | - Massimo Busin
- Department of Translational Medicine, University of Ferrara, 44121 Ferrara, Italy; (A.S.); (A.C.Y.); (M.B.)
| | - Giorgio Zauli
- Research Department, King Khaled Eye Specialist Hospital, Riyadh 11462, Saudi Arabia; (B.A.); (S.A.); (S.H.); (G.Z.)
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3
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Wilson K, Holjencin C, Lee H, Annamalai B, Ishii M, Gilbert JL, Jakymiw A, Rohrer B. Development of a cell-penetrating peptide-based nanocomplex for long-term delivery of intact mitochondrial DNA into epithelial cells. MOLECULAR THERAPY. NUCLEIC ACIDS 2025; 36:102449. [PMID: 39991470 PMCID: PMC11847061 DOI: 10.1016/j.omtn.2025.102449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2024] [Accepted: 01/10/2025] [Indexed: 02/25/2025]
Abstract
Gene therapy approaches for mitochondrial DNA (mtDNA)-associated damage/diseases have thus far been limited, and despite advancements in single gene therapy for mtDNA mutations and progress in mitochondrial transplantation, no method exists for restoring the entire mtDNA molecule in a clinically translatable manner. Here, we present for the first time a strategy to deliver an exogenous, fully intact, and healthy mtDNA template into cells to correct endogenous mtDNA mutations and deletions, with the potential to be developed into an efficient pan-therapy for inherited and/or acquired mtDNA disorders. More specifically, the novel therapeutic nanoparticle complex used in our study was generated by combining a cell-penetrating peptide (CPP) with purified mtDNA, in conjunction with a mitochondrial targeting reagent. The generated nanoparticle complexes were found to be taken up by cells and localized to mitochondria, with exogenous mtDNA retention/maintenance, along with mitochondrial RNA and protein production, observed in mitochondria-depleted ARPE-19 cells at least 4 weeks following a single treatment. These data demonstrate the feasibility of restoring mtDNA in cells via a CPP carrier, with the therapeutic potential to correct mtDNA damage independent of the number of gene mutations found within the mtDNA.
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Affiliation(s)
- Kyrie Wilson
- Department of Ophthalmology, College of Medicine, Medical University of South Carolina (MUSC), Charleston, SC 29425, USA
| | - Charles Holjencin
- Division of Basic Science Research, Department of Biomedical & Community Health Sciences, James B. Edwards College of Dental Medicine, MUSC, Charleston, SC 29425, USA
| | - Hwaran Lee
- Department of Bioengineering, Clemson University, Clemson – MUSC Bioengineering Program, MUSC, Charleston, SC 29425, USA
| | - Balasubramaniam Annamalai
- Department of Ophthalmology, College of Medicine, Medical University of South Carolina (MUSC), Charleston, SC 29425, USA
| | - Masaaki Ishii
- Department of Ophthalmology, College of Medicine, Medical University of South Carolina (MUSC), Charleston, SC 29425, USA
| | - Jeremy L. Gilbert
- Department of Bioengineering, Clemson University, Clemson – MUSC Bioengineering Program, MUSC, Charleston, SC 29425, USA
| | - Andrew Jakymiw
- Division of Basic Science Research, Department of Biomedical & Community Health Sciences, James B. Edwards College of Dental Medicine, MUSC, Charleston, SC 29425, USA
- Department of Biochemistry & Molecular Biology, College of Medicine, Hollings Cancer Center, MUSC, Charleston, SC 29425, USA
| | - Bärbel Rohrer
- Department of Ophthalmology, College of Medicine, Medical University of South Carolina (MUSC), Charleston, SC 29425, USA
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Li S, Su D, Hu S, Hu Q, Sun D. Epigallocatechin gallate ameliorates retinal pigment epithelial cell damage via the CYFIP2 /AKT pathway. Toxicol Appl Pharmacol 2025; 495:117124. [PMID: 39667565 DOI: 10.1016/j.taap.2024.117124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2024] [Revised: 09/27/2024] [Accepted: 10/07/2024] [Indexed: 12/14/2024]
Abstract
Age-related macular degeneration (AMD) is a representative age-related ophthalmic disease, and the pathogenesis of AMD remains unclear. This research intended to determine whether epigallocatechin gallate (EGCG) could alleviate the progression of AMD and the possible mechanism. We constructed three groups of mice (young, aged, and EGCG), and HE and TUNEL staining of retinal tissues was performed to observe the structural changes in the retinal pigment epithelial (RPE) layer and the level of apoptosis, respectively. Through RNA-Sequencing analysis of retinal tissues and by RT-qPCR, GO, KEGG, and literature analyses, we identified cytoplasmic fragile X mental retardation 1-interacting protein 2 (CYFIP2) as a possible effector gene for EGCG action and validated its role by immunofluorescent and western blotting experiments. The CCK-8 and Hoechst 33342 apoptosis assays, and western blotting and qRT-PCR assays showed that EGCG reduced hydrogen peroxide (H2O2)-induced apoptosis in adult human RPE (ARPE-19) cells, and the expression of Cyfip2 was changed accordingly. RNA interference analysis indicated that Cyfip2 knockdown alleviated H2O2-induced ARPE apoptosis, while its overexpression weakened EGCG's protective effect. Western blot analysis showed that Cyfip2 mediated the anti-apoptotic effect of EGCG by modulating the level of protein kinase B (Akt) phosphorylation in ARPE cells, and the activation level of phosphorylated AKT (p-AKT Ser473) in retinal tissue of the EGCG-fed group was higher than that of the aged group. Taken together, this study suggests that EGCG plays a protective role in the development of AMD and the apoptosis of ARPE cells through the Cyfip2/AKT pathway.
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Affiliation(s)
- Sijia Li
- Harbin Medical University, Harbin 150086, China; Hongqi Hospital of Mudanjiang Medical University, Mudanjiang 157011, Heilongjiang, China
| | - Dongmei Su
- Department of Genetics, NHC Key Laboratory of Reproductive Health Engineering Technology Research, National Research Institute for Family Planning, Health Department, Beijing 100081, China; Graduate School, Peking Union Medical College, Beijing 100081, China
| | - Shanshan Hu
- Hongqi Hospital of Mudanjiang Medical University, Mudanjiang 157011, Heilongjiang, China
| | - Qiang Hu
- Harbin Medical University, Harbin 150086, China
| | - Dawei Sun
- Department of Ophthalmology, the second affiliated hospital of Harbin Medical University, Harbin 150086, China.
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Kobayashi H, Matsubara S, Yoshimoto C, Shigetomi H, Imanaka S. A Comprehensive Review of the Contribution of Mitochondrial DNA Mutations and Dysfunction in Polycystic Ovary Syndrome, Supported by Secondary Database Analysis. Int J Mol Sci 2025; 26:1172. [PMID: 39940939 PMCID: PMC11818232 DOI: 10.3390/ijms26031172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2024] [Revised: 01/16/2025] [Accepted: 01/27/2025] [Indexed: 02/16/2025] Open
Abstract
Polycystic ovary syndrome (PCOS) is a common endocrine disorder affecting women of reproductive age characterized by a spectrum of clinical, metabolic, reproductive, and psychological abnormalities. This syndrome is associated with significant long-term health risks, necessitating elucidation of its pathophysiology, early diagnosis, and comprehensive management strategies. Several contributory factors in PCOS, including androgen excess and insulin resistance, collectively enhance oxidative stress, which subsequently leads to mitochondrial dysfunction. However, the precise mechanisms through which oxidative stress induces mitochondrial dysfunction remain incompletely understood. Comprehensive searches of electronic databases were conducted to identify relevant studies published up to 30 September 2024. Mitochondria, the primary sites of reactive oxygen species (ROS) generation, play critical roles in energy metabolism and cellular homeostasis. Oxidative stress can inflict damage on components, including lipids, proteins, and DNA. Damage to mitochondrial DNA (mtDNA), which lacks efficient repair mechanisms, may result in mutations that impair mitochondrial function. Dysfunctional mitochondrial activity further amplifies ROS production, thereby perpetuating oxidative stress. These disruptions are implicated in the complications associated with the syndrome. Advances in genetic analysis technologies, including next-generation sequencing, have identified point mutations and deletions in mtDNA, drawing significant attention to their association with oxidative stress. Emerging data from mtDNA mutation analyses challenge conventional paradigms and provide new insights into the role of oxidative stress in mitochondrial dysfunction. We are rethinking the pathogenesis of PCOS based on these database analyses. In conclusion, this review explores the intricate relationship between oxidative stress, mtDNA mutations, and mitochondrial dysfunction, offers an updated perspective on the pathophysiology of PCOS, and outlines directions for future research.
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Affiliation(s)
- Hiroshi Kobayashi
- Department of Gynecology and Reproductive Medicine, Ms.Clinic MayOne, 871-1 Shijo-cho, Kashihara 634-0813, Japan;
- Department of Obstetrics and Gynecology, Nara Medical University, 840 Shijo-cho, Kashihara 634-8522, Japan; (S.M.); (C.Y.); (H.S.)
| | - Sho Matsubara
- Department of Obstetrics and Gynecology, Nara Medical University, 840 Shijo-cho, Kashihara 634-8522, Japan; (S.M.); (C.Y.); (H.S.)
- Department of Medicine, Kei Oushin Clinic, 5-2-6 Naruo-cho, Nishinomiya 663-8184, Japan
| | - Chiharu Yoshimoto
- Department of Obstetrics and Gynecology, Nara Medical University, 840 Shijo-cho, Kashihara 634-8522, Japan; (S.M.); (C.Y.); (H.S.)
- Department of Obstetrics and Gynecology, Nara Prefecture General Medical Center, 2-897-5 Shichijyonishi-machi, Nara 630-8581, Japan
| | - Hiroshi Shigetomi
- Department of Obstetrics and Gynecology, Nara Medical University, 840 Shijo-cho, Kashihara 634-8522, Japan; (S.M.); (C.Y.); (H.S.)
- Department of Gynecology and Reproductive Medicine, Aska Ladies Clinic, 3-3-17 Kitatomigaoka-cho, Nara 634-0001, Japan
| | - Shogo Imanaka
- Department of Gynecology and Reproductive Medicine, Ms.Clinic MayOne, 871-1 Shijo-cho, Kashihara 634-0813, Japan;
- Department of Obstetrics and Gynecology, Nara Medical University, 840 Shijo-cho, Kashihara 634-8522, Japan; (S.M.); (C.Y.); (H.S.)
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Berlin A, Messinger JD, Ramtohul P, Balaratnasingam C, Mendis R, Ferrara D, Freund KB, Curcio CA. INFLAMMATORY CELL ACTIVITY IN TREATED NEOVASCULAR AGE-RELATED MACULAR DEGENERATION: A Histologic Case Study. Retina 2023; 43:1904-1913. [PMID: 37871271 PMCID: PMC10801910 DOI: 10.1097/iae.0000000000003881] [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] [Indexed: 07/27/2023]
Abstract
BACKGROUND Imaging indicators of macular neovascularization risk can help determine patient eligibility for new treatments for geographic atrophy secondary to age-related macular degeneration. Because type 1 macular neovascularization includes inflammation, we assessed by histology the distribution of cells with inflammatory potential in two fellow eyes with age-related macular degeneration. METHODS Two eyes of a White woman in her 90's with type 3 macular neovascularization treated with antivascular endothelial growth factor were prepared for high-resolution histology. Eye-tracked spectral domain optical coherence tomography applied to the preserved donor eyes linked in vivo imaging to histology. Cells were enumerated in the intraretinal, subretinal, and subretinal retinal pigment epithelium (RPE)-basal lamina compartments on 199 glass slides. Cells with numerous organelles were considered to RPE-derived; cells with sparse RPE organelles were considered non-RPE phagocytes. RESULTS Both eyes had soft drusen and abundant subretinal drusenoid deposit. In the retina and subretinal space, RPE-derived cells, including hyperreflective foci, were common (n = 125 and 73, respectively). Non-RPE phagocytes were infrequent (n = 5 in both). Over drusen, RPE morphology transitioned smoothly from the age-normal layer toward the top, suggesting transdifferentiation. The sub-RPE-basal lamina space had RPE-derived cells (n = 87) and non-RPE phagocytes (n = 49), including macrophages and giant cells. CONCLUSION Numerous sub-RPE-basal lamina cells of several types are consistent with the documented presence of proinflammatory lipids in drusen and aged Bruch's membrane. The relatively compartmentalized abundance of infiltrating cells suggests that drusen contents are more inflammatory than subretinal drusenoid deposit, perhaps reflecting their environments. Ectopic RPE occurs frequently. Some manifest as hyperreflective foci. More cells may be visible as optical coherence tomography technologies evolve.
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Affiliation(s)
- Andreas Berlin
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham AL, USA
- Department of Ophthalmology, University Hospital Würzburg, Würzburg, Germany
| | - Jeffrey D Messinger
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham AL, USA
| | | | - Chandrakumar Balaratnasingam
- Centre for Ophthalmology and Visual Science, University of Western Australia, Perth, Australia
- Lions Eye Institute, Nedlands, Western Australia, Australia
- Department of Ophthalmology, Sir Charles Gairdner Hospital, Western Australia, Australia
| | | | | | - K. Bailey Freund
- Vitreous Retina Macula Consultants of New York NY, USA
- Department of Ophthalmology, New York University Grossman School of Medicine, New York NY, USA
| | - Christine A Curcio
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham AL, USA
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Xu L, Yang K, Fan Q, Gu Y, Ren S. Mitochondrial DNA heteroplasmy analysis in keratoconus patients from China. Front Genet 2023; 14:1251951. [PMID: 37790701 PMCID: PMC10544337 DOI: 10.3389/fgene.2023.1251951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 09/05/2023] [Indexed: 10/05/2023] Open
Abstract
Background: Mitochondrial DNA (mtDNA) variants have been implicated in keratoconus (KC). The present study aimed to characterize the mtDNA heteroplasmy profile in KC and explore the association of mitochondrial heteroplasmic levels with KC. Methods: Mitochondrial sequencing of peripheral blood samples and corneal tomography were conducted in 300 KC cases and 300 matched controls. The number of heteroplasmic and homoplasmic variants was calculated across the mitochondrial genome. Spearman's correlation was used to analyze the correlation between the number of heteroplasmic variants and age. The association of mtDNA heteroplasmic level with KC was analyzed by logistic regression analysis. Moreover, the relationship between mitochondrial heteroplasmic levels and clinical parameters was determined by linear regression analysis. Results: The distribution of mtDNA heteroplasmic variants showed the highest number of heteroplasmic variants in the non-coding region, while the COX3 gene exhibited the highest number in protein-coding genes. Comparisons of the number of heteroplasmic and homoplasmic non-synonymous variants in protein-coding genes revealed no significant differences between KC cases and controls (all p > 0.05). In addition, the number of heteroplasmic variants was positively associated with age in all subjects (r = 0.085, p = 0.037). The logistic regression analyses indicated that the heteroplasmic levels of m.16180_16181delAA was associated with KC (p < 0.005). Linear regression analyses demonstrated that the heteroplasmic levels of m.16180_16181delAA and m.302A>C were not correlated with thinnest corneal thickness (TCT), steep keratometry (Ks), and flat keratometry (Kf) (all p > 0.05) in KC cases and controls separately. Conclusion: The current study characterized the mtDNA heteroplasmy profile in KC, and revealed that the heteroplasmic levels of m.16180_16181delAA were associated with KC.
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Affiliation(s)
| | | | | | | | - Shengwei Ren
- Henan Provincial People’s Hospital, Henan Eye Hospital, People’s Hospital of Zhengzhou University, Zhengzhou, China
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Abstract
Mitochondria are the main source of energy used to maintain cellular homeostasis. This aspect of mitochondrial biology underlies their putative role in age-associated tissue dysfunction. Proper functioning of the electron transport chain (ETC), which is partially encoded by the extra-nuclear mitochondrial genome (mtDNA), is key to maintaining this energy production. The acquisition of de novo somatic mutations that interrupt the function of the ETC have long been associated with aging and common diseases of the elderly. Yet, despite over 30 years of study, the exact role(s) mtDNA mutations play in driving aging and its associated pathologies remains under considerable debate. Furthermore, even fundamental aspects of age-related mtDNA mutagenesis, such as when mutations arise during aging, where and how often they occur across tissues, and the specific mechanisms that give rise to them, remain poorly understood. In this review, we address the current understanding of the somatic mtDNA mutations, with an emphasis of when, where, and how these mutations arise during aging. Additionally, we highlight current limitations in our knowledge and critically evaluate the controversies stemming from these limitations. Lastly, we highlight new and emerging technologies that offer potential ways forward in increasing our understanding of somatic mtDNA mutagenesis in the aging process.
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Affiliation(s)
- Monica Sanchez-Contreras
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, United States
| | - Scott R Kennedy
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, United States
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Leuthner TC, Meyer JN. Mitochondrial DNA Mutagenesis: Feature of and Biomarker for Environmental Exposures and Aging. Curr Environ Health Rep 2021; 8:294-308. [PMID: 34761353 PMCID: PMC8826492 DOI: 10.1007/s40572-021-00329-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/24/2021] [Indexed: 01/12/2023]
Abstract
PURPOSE OF REVIEW Mitochondrial dysfunction is a hallmark of aging. Mitochondrial genome (mtDNA) instability contributes to mitochondrial dysfunction, and mtDNA mutagenesis may contribute to aging. However, the origin of mtDNA mutations remains somewhat controversial. The goals of this review are to introduce and review recent literature on mtDNA mutagenesis and aging, address recent animal and epidemiological evidence for the effects of chemicals on mtDNA damage and mutagenesis, propose hypotheses regarding the contribution of environmental toxicant exposure to mtDNA mutagenesis in the context of aging, and suggest future directions and approaches for environmental health researchers. RECENT FINDINGS Stressors such as pollutants, pharmaceuticals, and ultraviolet radiation can damage the mitochondrial genome or disrupt mtDNA replication, repair, and organelle homeostatic processes, potentially influencing the rate of accumulation of mtDNA mutations. Accelerated mtDNA mutagenesis could contribute to aging, diseases of aging, and sensitize individuals with pathogenic mtDNA variants to stressors. We propose three potential mechanisms of toxicant-induced effects on mtDNA mutagenesis over lifespan: (1) increased de novo mtDNA mutations, (2) altered frequencies of mtDNA mutations, or (3) both. There are remarkably few studies that have investigated the impact of environmental chemical exposures on mtDNA instability and mutagenesis, and even fewer in the context of aging. More studies are warranted because people are exposed to tens of thousands of chemicals, and are living longer. Finally, we suggest that toxicant-induced mtDNA damage and mutational signatures may be a sensitive biomarker for some exposures.
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Affiliation(s)
- Tess C Leuthner
- Nicholas School of the Environment, 9 Circuit Dr, Box 90328, Duke University, NC, 27708, USA
| | - Joel N Meyer
- Nicholas School of the Environment, 9 Circuit Dr, Box 90328, Duke University, NC, 27708, USA.
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