1
|
García-López M, Jiménez-Vicente L, González-Jabardo R, Dorado H, Gómez-Manjón I, Martín MÁ, Ayuso C, Arenas J, Gallardo ME. Creation of an Isogenic Human iPSC-Based RGC Model of Dominant Optic Atrophy Harboring the Pathogenic Variant c.1861C>T (p.Gln621Ter) in the OPA1 Gene. Int J Mol Sci 2024; 25:7240. [PMID: 39000346 PMCID: PMC11242102 DOI: 10.3390/ijms25137240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2024] [Revised: 06/26/2024] [Accepted: 06/28/2024] [Indexed: 07/16/2024] Open
Abstract
Autosomal dominant optic atrophy (ADOA) is a rare progressive disease mainly caused by mutations in OPA1, a nuclear gene encoding for a mitochondrial protein that plays an essential role in mitochondrial dynamics, cell survival, oxidative phosphorylation, and mtDNA maintenance. ADOA is characterized by the degeneration of retinal ganglion cells (RGCs). This causes visual loss, which can lead to legal blindness in many cases. Nowadays, there is no effective treatment for ADOA. In this article, we have established an isogenic human RGC model for ADOA using iPSC technology and the genome editing tool CRISPR/Cas9 from a previously generated iPSC line of an ADOA plus patient harboring the pathogenic variant NM_015560.3: c.1861C>T (p.Gln621Ter) in heterozygosis in OPA1. To this end, a protocol based on supplementing the iPSC culture media with several small molecules and defined factors trying to mimic embryonic development has been employed. Subsequently, the created model was validated, confirming the presence of a defect of intergenomic communication, impaired mitochondrial respiration, and an increase in apoptosis and ROS generation. Finally, we propose the analysis of OPA1 expression by qPCR as an easy read-out method to carry out future drug screening studies using the created RGC model. In summary, this model provides a useful platform for further investigation of the underlying pathophysiological mechanisms of ADOA plus and for testing compounds with potential pharmacological action.
Collapse
Affiliation(s)
- Marta García-López
- Grupo de Investigación Traslacional con Células iPS, Instituto de Investigación Sanitaria Hospital 12 de Octubre (imas12), 28041 Madrid, Spain
| | - Lydia Jiménez-Vicente
- Grupo de Investigación Traslacional con Células iPS, Instituto de Investigación Sanitaria Hospital 12 de Octubre (imas12), 28041 Madrid, Spain
| | - Raquel González-Jabardo
- Grupo de Investigación Traslacional con Células iPS, Instituto de Investigación Sanitaria Hospital 12 de Octubre (imas12), 28041 Madrid, Spain
| | - Helena Dorado
- Grupo de Investigación Traslacional con Células iPS, Instituto de Investigación Sanitaria Hospital 12 de Octubre (imas12), 28041 Madrid, Spain
| | - Irene Gómez-Manjón
- Servicio de Genética, Hospital 12 de Octubre, Instituto de Investigación Sanitaria Hospital 12 de Octubre (imas12), 28041 Madrid, Spain
| | - Miguel Ángel Martín
- Servicio de Genética, Hospital 12 de Octubre, Instituto de Investigación Sanitaria Hospital 12 de Octubre (imas12), 28041 Madrid, Spain
- Laboratorio de Enfermedades Mitocondriales y Neuromusculares, Instituto de Investigación Sanitaria Hospital 12 de Octubre (imas12), 28041 Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 28029 Madrid, Spain
| | - Carmen Ayuso
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 28029 Madrid, Spain
- Department of Genetics & Genomics, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz University Hospital, Universidad Autónoma de Madrid (IIS-FJD, UAM), 28040 Madrid, Spain
| | - Joaquín Arenas
- Laboratorio de Enfermedades Mitocondriales y Neuromusculares, Instituto de Investigación Sanitaria Hospital 12 de Octubre (imas12), 28041 Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 28029 Madrid, Spain
| | - María Esther Gallardo
- Grupo de Investigación Traslacional con Células iPS, Instituto de Investigación Sanitaria Hospital 12 de Octubre (imas12), 28041 Madrid, Spain
| |
Collapse
|
2
|
Affortit C, Coyat C, Saidia AR, Ceccato JC, Charif M, Sarzi E, Flamant F, Guyot R, Cazevieille C, Puel JL, Lenaers G, Wang J. The human OPA1 delTTAG mutation induces adult onset and progressive auditory neuropathy in mice. Cell Mol Life Sci 2024; 81:80. [PMID: 38334784 PMCID: PMC10858076 DOI: 10.1007/s00018-024-05115-4] [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: 07/11/2023] [Revised: 01/05/2024] [Accepted: 01/05/2024] [Indexed: 02/10/2024]
Abstract
Dominant optic atrophy (DOA) is one of the most prevalent forms of hereditary optic neuropathies and is mainly caused by heterozygous variants in OPA1, encoding a mitochondrial dynamin-related large GTPase. The clinical spectrum of DOA has been extended to a wide variety of syndromic presentations, called DOAplus, including deafness as the main secondary symptom associated to vision impairment. To date, the pathophysiological mechanisms underlying the deafness in DOA remain unknown. To gain insights into the process leading to hearing impairment, we have analyzed the Opa1delTTAG mouse model that recapitulates the DOAplus syndrome through complementary approaches combining morpho-physiology, biochemistry, and cellular and molecular biology. We found that Opa1delTTAG mutation leads an adult-onset progressive auditory neuropathy in mice, as attested by the auditory brainstem response threshold shift over time. However, the mutant mice harbored larger otoacoustic emissions in comparison to wild-type littermates, whereas the endocochlear potential, which is a proxy for the functional state of the stria vascularis, was comparable between both genotypes. Ultrastructural examination of the mutant mice revealed a selective loss of sensory inner hair cells, together with a progressive degeneration of the axons and myelin sheaths of the afferent terminals of the spiral ganglion neurons, supporting an auditory neuropathy spectrum disorder (ANSD). Molecular assessment of cochlea demonstrated a reduction of Opa1 mRNA level by greater than 40%, supporting haploinsufficiency as the disease mechanism. In addition, we evidenced an early increase in Sirtuin 3 level and in Beclin1 activity, and subsequently an age-related mtDNA depletion, increased oxidative stress, mitophagy as well as an impaired autophagic flux. Together, these results support a novel role for OPA1 in the maintenance of inner hair cells and auditory neural structures, addressing new challenges for the exploration and treatment of OPA1-linked ANSD in patients.
Collapse
Affiliation(s)
- Corentin Affortit
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, UMR 1298, 80 Rue Augustin Fliche, 34295, Montpellier, France
- Molecular Otolaryngology and Renal Research Laboratories, Department of Otolaryngology, Head and Neck Surgery, University of Iowa, Iowa City, IA, 52242, USA
| | - Carolanne Coyat
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, UMR 1298, 80 Rue Augustin Fliche, 34295, Montpellier, France
| | - Anissa Rym Saidia
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, UMR 1298, 80 Rue Augustin Fliche, 34295, Montpellier, France
| | - Jean-Charles Ceccato
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, UMR 1298, 80 Rue Augustin Fliche, 34295, Montpellier, France
| | - Majida Charif
- Genetics, and Immuno-Cell Therapy Team, Mohamed First University, 60000, Oujda, Morocco
| | - Emmanuelle Sarzi
- Institut NeuroMyoGène, Pathophysiology and Genetics of Neuron and Muscle (INMG-PGNM) UCBL-CNRS UMR5261, Inserm U1315, Université Claude Bernard, Lyon I, Faculty of Medicine and Pharmacy, Lyon, France
| | - Frédéric Flamant
- Institut de Génomique Fonctionnelle de Lyon (IGFL), INRAE USC1370, CNRS (UMR5242), ENS Lyon, Lyon, France
| | - Romain Guyot
- Institut de Génomique Fonctionnelle de Lyon (IGFL), INRAE USC1370, CNRS (UMR5242), ENS Lyon, Lyon, France
| | - Chantal Cazevieille
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, UMR 1298, 80 Rue Augustin Fliche, 34295, Montpellier, France
| | - Jean-Luc Puel
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, UMR 1298, 80 Rue Augustin Fliche, 34295, Montpellier, France
| | - Guy Lenaers
- Université Angers, MitoLab Team, Unité MitoVasc, UMR CNRS 6015, INSERM U1083, SFR ICAT, Angers, France
- Service de Neurologie, CHU d'Angers, Angers, France
| | - Jing Wang
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, UMR 1298, 80 Rue Augustin Fliche, 34295, Montpellier, France.
- Department of ENT and Head and Neck Surgery, University Hospital of Montpellier, Montpellier, France.
| |
Collapse
|
3
|
Picca A, Guerra F, Calvani R, Romano R, Coelho-Junior HJ, Bucci C, Leeuwenburgh C, Marzetti E. Mitochondrial-derived vesicles in skeletal muscle remodeling and adaptation. Semin Cell Dev Biol 2023; 143:37-45. [PMID: 35367122 DOI: 10.1016/j.semcdb.2022.03.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 02/25/2022] [Accepted: 03/19/2022] [Indexed: 12/24/2022]
Abstract
Mitochondrial remodeling is crucial to meet the bioenergetic demand to support muscle contractile activity during daily tasks and muscle regeneration following injury. A set of mitochondrial quality control (MQC) processes, including mitochondrial biogenesis, dynamics, and mitophagy, are in place to maintain a well-functioning mitochondrial network and support muscle regeneration. Alterations in any of these pathways compromises mitochondrial quality and may potentially lead to impaired myogenesis, defective muscle regeneration, and ultimately loss of muscle function. Among MQC processes, mitophagy has gained special attention for its implication in the clearance of dysfunctional mitochondria via crosstalk with the endo-lysosomal system, a major cell degradative route. Along this pathway, additional opportunities for mitochondrial disposal have been identified that may also signal at the systemic level. This communication occurs via inclusion of mitochondrial components within membranous shuttles named mitochondrial-derived vesicles (MDVs). Here, we discuss MDV generation and release as a mitophagy-complementing route for the maintenance of mitochondrial homeostasis in skeletal myocytes. We also illustrate the possible role of muscle-derived MDVs in immune signaling during muscle remodeling and adaptation.
Collapse
Affiliation(s)
- Anna Picca
- Fondazione Policlinico Universitario "Agostino Gemelli" IRCCS, Rome, Italy
| | - Flora Guerra
- Department of Biological and Environmental Sciences and Technologies, Università del Salento, Lecce, Italy
| | - Riccardo Calvani
- Fondazione Policlinico Universitario "Agostino Gemelli" IRCCS, Rome, Italy
| | - Roberta Romano
- Department of Biological and Environmental Sciences and Technologies, Università del Salento, Lecce, Italy
| | | | - Cecilia Bucci
- Department of Biological and Environmental Sciences and Technologies, Università del Salento, Lecce, Italy
| | - Christiaan Leeuwenburgh
- Department of Aging and Geriatric Research, Institute on Aging, Division of Biology of Aging, University of Florida, Gainesville, USA
| | - Emanuele Marzetti
- Fondazione Policlinico Universitario "Agostino Gemelli" IRCCS, Rome, Italy; Università Cattolica del Sacro Cuore, Department of Geriatrics and Orthopedics, Rome, Italy.
| |
Collapse
|
4
|
Sladen PE, Jovanovic K, Guarascio R, Ottaviani D, Salsbury G, Novoselova T, Chapple JP, Yu-Wai-Man P, Cheetham ME. Modelling autosomal dominant optic atrophy associated with OPA1 variants in iPSC-derived retinal ganglion cells. Hum Mol Genet 2022; 31:3478-3493. [PMID: 35652445 PMCID: PMC9558835 DOI: 10.1093/hmg/ddac128] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 05/11/2022] [Accepted: 05/26/2022] [Indexed: 11/14/2022] Open
Abstract
Autosomal dominant optic atrophy (DOA) is the most common inherited optic neuropathy, characterized by the preferential loss of retinal ganglion cells (RGCs), resulting in optic nerve degeneration and progressive bilateral central vision loss. More than 60% of genetically confirmed patients with DOA carry variants in the nuclear OPA1 gene, which encodes for a ubiquitously expressed, mitochondrial GTPase protein. OPA1 has diverse functions within the mitochondrial network, facilitating inner membrane fusion and cristae modelling, regulating mitochondrial DNA maintenance and coordinating mitochondrial bioenergetics. There are currently no licensed disease-modifying therapies for DOA and the disease mechanisms driving RGC degeneration are poorly understood. Here, we describe the generation of isogenic, heterozygous OPA1 null induced pluripotent stem cell (iPSC) (OPA1+/-) through clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 gene editing of a control cell line, in conjunction with the generation of DOA patient-derived iPSC carrying OPA1 variants, namely, the c.2708_2711delTTAG variant (DOA iPSC), and previously reported missense variant iPSC line (c.1334G>A, DOA plus [DOA]+ iPSC) and CRISPR/Cas9 corrected controls. A two-dimensional (2D) differentiation protocol was used to study the effect of OPA1 variants on iPSC-RGC differentiation and mitochondrial function. OPA1+/-, DOA and DOA+ iPSC showed no differentiation deficit compared to control iPSC lines, exhibiting comparable expression of all relevant markers at each stage of differentiation. OPA1+/- and OPA1 variant iPSC-RGCs exhibited impaired mitochondrial homeostasis, with reduced bioenergetic output and compromised mitochondrial DNA maintenance. These data highlight mitochondrial deficits associated with OPA1 dysfunction in human iPSC-RGCs, and establish a platform to study disease mechanisms that contribute to RGC loss in DOA, as well as potential therapeutic interventions.
Collapse
Affiliation(s)
- Paul E Sladen
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | | | | | - Daniele Ottaviani
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
- Department of Biology, University of Padua, and Veneto Institute of Molecular Medicine, Padua 35129, Italy
| | - Grace Salsbury
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | - Tatiana Novoselova
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | - J Paul Chapple
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | - Patrick Yu-Wai-Man
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK
- Cambridge Eye Unit, Addenbrooke’s Hospital, Cambridge University Hospital, Cambridge CB2 0QQ, UK
- Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0PY, UK
| | | |
Collapse
|
5
|
Ahmad I. CRISPR/Cas9-A Promising Therapeutic Tool to Cure Blindness: Current Scenario and Future Prospects. Int J Mol Sci 2022; 23:11482. [PMID: 36232782 PMCID: PMC9569777 DOI: 10.3390/ijms231911482] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 09/24/2022] [Accepted: 09/26/2022] [Indexed: 11/16/2022] Open
Abstract
CRISPR-based targeted genome editing is bringing revolutionary changes in the research arena of biological sciences. CRISPR/Cas9 has been explored as an efficient therapeutic tool for the treatment of genetic diseases. It has been widely used in ophthalmology research by using mouse models to correct pathogenic mutations in the eye stem cells. In recent studies, CRISPR/Cas9 has been used to correct a large number of mutations related to inherited retinal disorders. In vivo therapeutic advantages for retinal diseases have been successfully achieved in some rodents. Current advances in the CRISPR-based gene-editing domain, such as modified Cas variants and delivery approaches have optimized its application to treat blindness. In this review, recent progress and challenges of the CRISPR-Cas system have been discussed to cure blindness and its prospects.
Collapse
Affiliation(s)
- Irshad Ahmad
- Department of Bioengineering, King Fahd University of Petroleum and Minerals (KFUPM), Dhahran 31261, Saudi Arabia; ; Tel.: +966-13-8608393
- Interdisciplinary Research Center for Membranes and Water Security, King Fahd University of Petroleum and Minerals (KFUPM), Dhahran 31261, Saudi Arabia
| |
Collapse
|
6
|
Sladen PE, Perdigão PR, Salsbury G, Novoselova T, van der Spuy J, Chapple JP, Yu-Wai-Man P, Cheetham ME. CRISPR-Cas9 correction of OPA1 c.1334G>A: p.R445H restores mitochondrial homeostasis in dominant optic atrophy patient-derived iPSCs. MOLECULAR THERAPY. NUCLEIC ACIDS 2021; 26:432-443. [PMID: 34589289 PMCID: PMC8455316 DOI: 10.1016/j.omtn.2021.08.015] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 08/09/2021] [Indexed: 12/26/2022]
Abstract
Autosomal dominant optic atrophy (DOA) is the most common inherited optic neuropathy in the United Kingdom. DOA has an insidious onset in early childhood, typically presenting with bilateral, central visual loss caused by the preferential loss of retinal ganglion cells. 60%-70% of genetically confirmed DOA cases are associated with variants in OPA1, a ubiquitously expressed GTPase that regulates mitochondrial homeostasis through coordination of inner membrane fusion, maintenance of cristae structure, and regulation of bioenergetic output. Whether genetic correction of OPA1 pathogenic variants can alleviate disease-associated phenotypes remains unknown. Here, we demonstrate generation of patient-derived OPA1 c.1334G>A: p.R445H mutant induced pluripotent stem cells (iPSCs), followed by correction of OPA1 through CRISPR-Cas9-guided homology-directed repair (HDR) and evaluate the effect of OPA1 correction on mitochondrial homeostasis. CRISPR-Cas9 gene editing demonstrated an efficient method of OPA1 correction, with successful gene correction in 57% of isolated iPSCs. Correction of OPA1 restored mitochondrial homeostasis, re-establishing the mitochondrial network and basal respiration and ATP production levels. In addition, correction of OPA1 re-established the levels of wild-type (WT) mitochondrial DNA (mtDNA) and reduced susceptibility to apoptotic stimuli. These data demonstrate that nuclear gene correction can restore mitochondrial homeostasis and improve mtDNA integrity in DOA patient-derived cells carrying an OPA1 variant.
Collapse
Affiliation(s)
- Paul E. Sladen
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | | | - Grace Salsbury
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | - Tatiana Novoselova
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | | | - J. Paul Chapple
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | - Patrick Yu-Wai-Man
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK
- Cambridge Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, ED Adrian Building, Robinson Way, Cambridge CB2 0PY, UK
- John van Geest Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0PY, UK
| | | |
Collapse
|
7
|
Zou W, Ji D, Zhang Z, Yang L, Cao Y. Players in Mitochondrial Dynamics and Female Reproduction. Front Mol Biosci 2021; 8:717328. [PMID: 34708072 PMCID: PMC8542886 DOI: 10.3389/fmolb.2021.717328] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 09/07/2021] [Indexed: 01/16/2023] Open
Abstract
Mitochondrial dynamics (fission and fusion) are essential physiological processes for mitochondrial metabolic function, mitochondrial redistribution, and mitochondrial quality control. Various proteins are involved in regulating mitochondrial dynamics. Aberrant expression of these proteins interferes with mitochondrial dynamics and induces a range of diseases. Multiple therapeutic approaches have been developed to treat the related diseases in recent years, but their curative effects are limited. Meanwhile, the role of mitochondrial dynamics in female reproductive function has attracted progressively more attention, including oocyte development and maturation, fertilization, and embryonic development. Here, we reviewed the significance of mitochondrial dynamics, proteins involved in mitochondrial dynamics, and disorders resulting from primary mitochondrial dynamic dysfunction. We summarized the latest therapeutic approaches of hereditary mitochondrial fusion-fission abnormalities and reviewed the recent advances in female reproductive mitochondrial dynamics.
Collapse
Affiliation(s)
- Weiwei Zou
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, The First Affiliated Hospital of Anhui Medical University, Hefei, China.,NHC Key Laboratory of Study on Abnormal Gametes and Reproductive Tract (Anhui Medical University), Hefei, China.,Key Laboratory of Population Health Across Life Cycle (Anhui Medical University), Ministry of Education of the People's Republic of China, Hefei, China
| | - Dongmei Ji
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, The First Affiliated Hospital of Anhui Medical University, Hefei, China.,Anhui Province Key Laboratory of Reproductive Health and Genetics, Hefei, China.,Biopreservation and Artificial Organs, Anhui Provincial Engineering Research Center, Anhui Medical University, Hefei, China
| | - Zhiguo Zhang
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, The First Affiliated Hospital of Anhui Medical University, Hefei, China.,Anhui Province Key Laboratory of Reproductive Health and Genetics, Hefei, China.,Biopreservation and Artificial Organs, Anhui Provincial Engineering Research Center, Anhui Medical University, Hefei, China
| | - Li Yang
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
| | - Yunxia Cao
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, The First Affiliated Hospital of Anhui Medical University, Hefei, China.,NHC Key Laboratory of Study on Abnormal Gametes and Reproductive Tract (Anhui Medical University), Hefei, China.,Key Laboratory of Population Health Across Life Cycle (Anhui Medical University), Ministry of Education of the People's Republic of China, Hefei, China
| |
Collapse
|
8
|
Sun C, Wu X, Bai HX, Wang C, Liu Z, Yang C, Lu Y, Jiang P. OPA1 haploinsufficiency due to a novel splicing variant resulting in mitochondrial dysfunction without mitochondrial DNA depletion. Ophthalmic Genet 2020; 42:45-52. [PMID: 33251885 DOI: 10.1080/13816810.2020.1849313] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Background: To identify and investigate the effects of a novel splicing variant, c.1444-2A>C of OPA1, on its transcript, translation, and mitochondrial function, which was found in an 8-year-old patient with dominantly inherited optic atrophy (DOA). Materials and Methods: The clinical evaluations were performed at the Eye Center. Lymphoblast cell lines were generated from the patient, mother, and a normal control with the same haplotype of mitochondrial genome. The novel variant was confirmed by Sanger sequencing. The splicing alteration of cDNA was checked by both Sanger sequencing and agarose gel. OPA1 expression was carried out by RT-PCR and Western blotting. Transmission electron microscopy was used for mitochondrial morphology. Mitochondrial functions, including the rates of oxygen consumption, ATP generation, ROS product and membrane potential were assayed in lymphoblast cells. Results: The novel OPA1 splicing variant, c.1444-2A>C, led to a deletion of the 15th exon in mRNA transcript. Approximately 50% reduction of mRNA and protein expression was present in mutant cells as compared with controls. No marked depletion of mtDNA nor mitochondrial mass was caused by the splicing variant. However, defects that the impaired capacity of OXPHOS, reduced ATP generation, increased ROS and decreased membrane potential were observed in the mutant cells, which promoted a ubiquitin-binding mitophagy instead of apoptosis. Conclusions: The novel splicing variant, c.1444-2A>C resulted in OPA1 haploinsufficiency effect on its expression and mitochondrial function without mtDNA depletion. Our findings may provide new insights into the understanding of pathophysiology of DOA.
Collapse
Affiliation(s)
- Chuanbin Sun
- Eye Center, The Second Affiliated Hospital of Zhejiang University School of Medicine , Hangzhou, China
| | - Xiaoyu Wu
- Division of Medical Genetics and Genomics, the Children's Hospitals, Zhejiang University School of Medicine, National Clinical Research Center for Child Health , Hangzhou, China
| | - Hai-Xia Bai
- Eye Center, The Second Affiliated Hospital of Zhejiang University School of Medicine , Hangzhou, China
| | - Chenghui Wang
- Division of Medical Genetics and Genomics, the Children's Hospitals, Zhejiang University School of Medicine, National Clinical Research Center for Child Health , Hangzhou, China
| | - Zhe Liu
- Department of Ophthalmology, Zhejiang Provincial People's Hospital , Hangzhou, China
| | - Chenxi Yang
- Division of Medical Genetics and Genomics, the Children's Hospitals, Zhejiang University School of Medicine, National Clinical Research Center for Child Health , Hangzhou, China
| | - Yijun Lu
- Division of Medical Genetics and Genomics, the Children's Hospitals, Zhejiang University School of Medicine, National Clinical Research Center for Child Health , Hangzhou, China
| | - Pingping Jiang
- Division of Medical Genetics and Genomics, the Children's Hospitals, Zhejiang University School of Medicine, National Clinical Research Center for Child Health , Hangzhou, China
| |
Collapse
|
9
|
Chapman J, Ng YS, Nicholls TJ. The Maintenance of Mitochondrial DNA Integrity and Dynamics by Mitochondrial Membranes. Life (Basel) 2020; 10:life10090164. [PMID: 32858900 PMCID: PMC7555930 DOI: 10.3390/life10090164] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 08/20/2020] [Accepted: 08/23/2020] [Indexed: 12/18/2022] Open
Abstract
Mitochondria are complex organelles that harbour their own genome. Mitochondrial DNA (mtDNA) exists in the form of a circular double-stranded DNA molecule that must be replicated, segregated and distributed around the mitochondrial network. Human cells typically possess between a few hundred and several thousand copies of the mitochondrial genome, located within the mitochondrial matrix in close association with the cristae ultrastructure. The organisation of mtDNA around the mitochondrial network requires mitochondria to be dynamic and undergo both fission and fusion events in coordination with the modulation of cristae architecture. The dysregulation of these processes has profound effects upon mtDNA replication, manifesting as a loss of mtDNA integrity and copy number, and upon the subsequent distribution of mtDNA around the mitochondrial network. Mutations within genes involved in mitochondrial dynamics or cristae modulation cause a wide range of neurological disorders frequently associated with defects in mtDNA maintenance. This review aims to provide an understanding of the biological mechanisms that link mitochondrial dynamics and mtDNA integrity, as well as examine the interplay that occurs between mtDNA, mitochondrial dynamics and cristae structure.
Collapse
Affiliation(s)
- James Chapman
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK;
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Correspondence: (J.C.); (T.J.N.)
| | - Yi Shiau Ng
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK;
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Thomas J. Nicholls
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK;
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Correspondence: (J.C.); (T.J.N.)
| |
Collapse
|
10
|
Riley JS, Tait SW. Mitochondrial DNA in inflammation and immunity. EMBO Rep 2020; 21:e49799. [PMID: 32202065 PMCID: PMC7132203 DOI: 10.15252/embr.201949799] [Citation(s) in RCA: 451] [Impact Index Per Article: 112.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 01/31/2020] [Accepted: 03/03/2020] [Indexed: 12/14/2022] Open
Abstract
Mitochondria are cellular organelles that orchestrate a vast range of biological processes, from energy production and metabolism to cell death and inflammation. Despite this seemingly symbiotic relationship, mitochondria harbour within them a potent agonist of innate immunity: their own genome. Release of mitochondrial DNA into the cytoplasm and out into the extracellular milieu activates a plethora of different pattern recognition receptors and innate immune responses, including cGAS‐STING, TLR9 and inflammasome formation leading to, among others, robust type I interferon responses. In this Review, we discuss how mtDNA can be released from the mitochondria, the various inflammatory pathways triggered by mtDNA release and its myriad biological consequences for health and disease.
Collapse
Affiliation(s)
- Joel S Riley
- Cancer Research UK Beatson Institute, Glasgow, UK.,Institute of Cancer Sciences, University of Glasgow, Glasgow, UK
| | - Stephen Wg Tait
- Cancer Research UK Beatson Institute, Glasgow, UK.,Institute of Cancer Sciences, University of Glasgow, Glasgow, UK
| |
Collapse
|
11
|
Shim HB, Arshad O, Gadawska I, Côté HCF, Hsieh AYY. Platelet mtDNA content and leukocyte count influence whole blood mtDNA content. Mitochondrion 2020; 52:108-114. [PMID: 32156645 DOI: 10.1016/j.mito.2020.03.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 02/28/2020] [Accepted: 03/04/2020] [Indexed: 02/06/2023]
Abstract
Changes in whole blood (WB) mitochondrial DNA (mtDNA) content are associated with health and disease. Platelet-derived mtDNA can confound WB mtDNA content measurements. From a sample of 44 volunteers, we show that platelet mtDNA content and platelet:leukocyte ratio are both dependent predictors of WB mtDNA content, but that platelet count itself is not. Furthermore, when platelet:leukocyte ratio increased by <2-fold ex vivo, the effect on WB mtDNA content was minimal. Altogether, this study clarifies the contribution of platelet mtDNA content rather than platelet count on WB mtDNA content measurements, and identifies defined parameters for future research on WB mtDNA content.
Collapse
Affiliation(s)
- Hanjoo B Shim
- Centre for Blood Research, University of British Columbia, 2350 Health Sciences Mall #4302, Vancouver, British Columbia, Canada
| | - Omair Arshad
- Centre for Blood Research, University of British Columbia, 2350 Health Sciences Mall #4302, Vancouver, British Columbia, Canada; Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
| | - Izabella Gadawska
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
| | - Hélène C F Côté
- Centre for Blood Research, University of British Columbia, 2350 Health Sciences Mall #4302, Vancouver, British Columbia, Canada; Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada; Women's Health Research Institute, Vancouver, British Columbia, Canada.
| | - Anthony Y Y Hsieh
- Centre for Blood Research, University of British Columbia, 2350 Health Sciences Mall #4302, Vancouver, British Columbia, Canada; Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
| |
Collapse
|
12
|
Donkervoort S, Sabouny R, Yun P, Gauquelin L, Chao KR, Hu Y, Al Khatib I, Töpf A, Mohassel P, Cummings BB, Kaur R, Saade D, Moore SA, Waddell LB, Farrar MA, Goodrich JK, Uapinyoying P, Chan SHS, Javed A, Leach ME, Karachunski P, Dalton J, Medne L, Harper A, Thompson C, Thiffault I, Specht S, Lamont RE, Saunders C, Racher H, Bernier FP, Mowat D, Witting N, Vissing J, Hanson R, Coffman KA, Hainlen M, Parboosingh JS, Carnevale A, Yoon G, Schnur RE, Boycott KM, Mah JK, Straub V, Foley AR, Innes AM, Bönnemann CG, Shutt TE. MSTO1 mutations cause mtDNA depletion, manifesting as muscular dystrophy with cerebellar involvement. Acta Neuropathol 2019; 138:1013-1031. [PMID: 31463572 PMCID: PMC6851037 DOI: 10.1007/s00401-019-02059-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 07/25/2019] [Accepted: 08/08/2019] [Indexed: 01/12/2023]
Abstract
MSTO1 encodes a cytosolic mitochondrial fusion protein, misato homolog 1 or MSTO1. While the full genotype-phenotype spectrum remains to be explored, pathogenic variants in MSTO1 have recently been reported in a small number of patients presenting with a phenotype of cerebellar ataxia, congenital muscle involvement with histologic findings ranging from myopathic to dystrophic and pigmentary retinopathy. The proposed underlying pathogenic mechanism of MSTO1-related disease is suggestive of impaired mitochondrial fusion secondary to a loss of function of MSTO1. Disorders of mitochondrial fusion and fission have been shown to also lead to mitochondrial DNA (mtDNA) depletion, linking them to the mtDNA depletion syndromes, a clinically and genetically diverse class of mitochondrial diseases characterized by a reduction of cellular mtDNA content. However, the consequences of pathogenic variants in MSTO1 on mtDNA maintenance remain poorly understood. We present extensive phenotypic and genetic data from 12 independent families, including 15 new patients harbouring a broad array of bi-allelic MSTO1 pathogenic variants, and we provide functional characterization from seven MSTO1-related disease patient fibroblasts. Bi-allelic loss-of-function variants in MSTO1 manifest clinically with a remarkably consistent phenotype of childhood-onset muscular dystrophy, corticospinal tract dysfunction and early-onset non-progressive cerebellar atrophy. MSTO1 protein was not detectable in the cultured fibroblasts of all seven patients evaluated, suggesting that pathogenic variants result in a loss of protein expression and/or affect protein stability. Consistent with impaired mitochondrial fusion, mitochondrial networks in fibroblasts were found to be fragmented. Furthermore, all fibroblasts were found to have depletion of mtDNA ranging from 30 to 70% along with alterations to mtDNA nucleoids. Our data corroborate the role of MSTO1 as a mitochondrial fusion protein and highlight a previously unrecognized link to mtDNA regulation. As impaired mitochondrial fusion is a recognized cause of mtDNA depletion syndromes, this novel link to mtDNA depletion in patient fibroblasts suggests that MSTO1-deficiency should also be considered a mtDNA depletion syndrome. Thus, we provide mechanistic insight into the disease pathogenesis associated with MSTO1 mutations and further define the clinical spectrum and the natural history of MSTO1-related disease.
Collapse
Affiliation(s)
- S Donkervoort
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - R Sabouny
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Canada
| | - P Yun
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - L Gauquelin
- Division of Clinical and Metabolic Genetics, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
- Division of Neurology, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - K R Chao
- Center for Mendelian Genomics, Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Boston, MA, USA
| | - Y Hu
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - I Al Khatib
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Canada
| | - A Töpf
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - P Mohassel
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - B B Cummings
- Center for Mendelian Genomics, Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Boston, MA, USA
| | - R Kaur
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - D Saade
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - S A Moore
- Department of Pathology Carver College of Medicine, The University of Iowa, Iowa City, IA, USA
| | - L B Waddell
- Kids Neuroscience Centre, Kids Research, The Children's Hospital at Westmead, Sydney, NSW 2145, Australia
- Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Westmead, NSW 2145, Australia
| | - M A Farrar
- Department of Neurology, Sydney Children's Hospital, Sydney, NSW, Australia
- UNSW Sydney, School of Women's and Children's Health, Sydney, NSW, Australia
| | - J K Goodrich
- Center for Mendelian Genomics, Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Boston, MA, USA
| | - P Uapinyoying
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
- Research for Genetic Medicine, Children's National Medical Center, Washington, DC, USA
| | - S H S Chan
- Department of Paediatrics and Adolescent Medicine, Queen Mary Hospital, The University of Hong Kong, Hong Kong SAR, China
| | - A Javed
- School of Biomedical Science, The University of Hong Kong, Hong Kong SAR, China
| | - M E Leach
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
- Oregon Health and Science University, Neuromuscular Program, Doernbecher Children's Hospital, Portland, OR, USA
| | - P Karachunski
- Department of Neurology, University of Minnesota, Minneapolis, MN, USA
| | - J Dalton
- Department of Neurology, University of Minnesota, Minneapolis, MN, USA
| | - L Medne
- Division of Human Genetics, The Children's Hospital of Philadelphia, Philadelphia, USA
| | - A Harper
- Department of Neurology, Virginia Commonwealth University, Children's Hospital of Richmond at VCU, Richmond, VA, USA
| | - C Thompson
- Department of Pediatrics, University of California San Diego, San Diego, CA, USA
| | - I Thiffault
- Department of Pathology and Laboratory Medicine, Children's Mercy Hospital, Kansas City, USA
- Center for Pediatric Genomic Medicine, Children's Mercy Hospital, Kansas City, USA
- University of Missouri-Kansas City School of Medicine, Kansas City, USA
| | - S Specht
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - R E Lamont
- Department of Medical Genetics and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - C Saunders
- Department of Pathology and Laboratory Medicine, Children's Mercy Hospital, Kansas City, USA
- Center for Pediatric Genomic Medicine, Children's Mercy Hospital, Kansas City, USA
- University of Missouri-Kansas City School of Medicine, Kansas City, USA
| | - H Racher
- Department of Medical Genetics and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - F P Bernier
- Department of Medical Genetics and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - D Mowat
- UNSW Sydney, School of Women's and Children's Health, Sydney, NSW, Australia
- Department of Medical Genetics, Sydney Children's Hospital, Sydney, NSW, Australia
| | - N Witting
- Department of Neurology, University Hospital Rigshospitalet, Copenhagen, Denmark
| | - J Vissing
- Department of Neurology, University Hospital Rigshospitalet, Copenhagen, Denmark
| | - R Hanson
- University of Missouri-Kansas City School of Medicine, Kansas City, USA
- Department of Pediatrics, Children's Mercy Hospital, Kansas City, USA
| | - K A Coffman
- Department of Pediatrics, Children's Mercy Hospital, Kansas City, USA
- Division of Neurology, Children's Mercy Hospital, Kansas City, USA
| | - M Hainlen
- Department of Pediatrics, Children's Mercy Hospital, Kansas City, USA
- Division of Neurology, Children's Mercy Hospital, Kansas City, USA
| | - J S Parboosingh
- Department of Medical Genetics and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - A Carnevale
- Division of Clinical and Metabolic Genetics, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - G Yoon
- Division of Clinical and Metabolic Genetics, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
- Division of Neurology, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | | | - K M Boycott
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Canada
- Care4Rare Research Consortium, Ottawa, Canada
| | - J K Mah
- Departments of Pediatrics, Section of Neurology, University of Calgary, Calgary, AB, Canada
| | - V Straub
- John Walton Muscular Dystrophy Research Centre, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
- Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - A Reghan Foley
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - A M Innes
- Department of Medical Genetics and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - C G Bönnemann
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA.
| | - T E Shutt
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Canada.
- Department of Medical Genetics, Alberta Children's Hospital Research Institute, Hotchkiss Brain Institute, University of Calgary, Calgary, Canada.
| |
Collapse
|
13
|
Kondadi AK, Anand R, Reichert AS. Functional Interplay between Cristae Biogenesis, Mitochondrial Dynamics and Mitochondrial DNA Integrity. Int J Mol Sci 2019; 20:ijms20174311. [PMID: 31484398 PMCID: PMC6747513 DOI: 10.3390/ijms20174311] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 08/30/2019] [Accepted: 08/30/2019] [Indexed: 12/11/2022] Open
Abstract
Mitochondria are vital cellular organelles involved in a plethora of cellular processes such as energy conversion, calcium homeostasis, heme biogenesis, regulation of apoptosis and ROS reactive oxygen species (ROS) production. Although they are frequently depicted as static bean-shaped structures, our view has markedly changed over the past few decades as many studies have revealed a remarkable dynamicity of mitochondrial shapes and sizes both at the cellular and intra-mitochondrial levels. Aberrant changes in mitochondrial dynamics and cristae structure are associated with ageing and numerous human diseases (e.g., cancer, diabetes, various neurodegenerative diseases, types of neuro- and myopathies). Another unique feature of mitochondria is that they harbor their own genome, the mitochondrial DNA (mtDNA). MtDNA exists in several hundreds to thousands of copies per cell and is arranged and packaged in the mitochondrial matrix in structures termed mt-nucleoids. Many human diseases are mechanistically linked to mitochondrial dysfunction and alteration of the number and/or the integrity of mtDNA. In particular, several recent studies identified remarkable and partly unexpected links between mitochondrial structure, fusion and fission dynamics, and mtDNA. In this review, we will provide an overview about these recent insights and aim to clarify how mitochondrial dynamics, cristae ultrastructure and mtDNA structure influence each other and determine mitochondrial functions.
Collapse
Affiliation(s)
- Arun Kumar Kondadi
- Institute of Biochemistry and Molecular Biology I, Medical Faculty, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany.
| | - Ruchika Anand
- Institute of Biochemistry and Molecular Biology I, Medical Faculty, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Andreas S Reichert
- Institute of Biochemistry and Molecular Biology I, Medical Faculty, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany.
| |
Collapse
|
14
|
Sabouny R, Wong R, Lee-Glover L, Greenway SC, Sinasac DS, Khan A, Shutt TE. Characterization of the C584R variant in the mtDNA depletion syndrome gene FBXL4, reveals a novel role for FBXL4 as a regulator of mitochondrial fusion. Biochim Biophys Acta Mol Basis Dis 2019; 1865:165536. [PMID: 31442532 DOI: 10.1016/j.bbadis.2019.165536] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 07/16/2019] [Accepted: 08/18/2019] [Indexed: 12/16/2022]
Abstract
Mutations in FBXL4 (F-Box and Leucine rich repeat protein 4), a nuclear-encoded mitochondrial protein with an unknown function, cause mitochondrial DNA depletion syndrome. We report two siblings, from consanguineous parents, harbouring a previously uncharacterized homozygous variant in FBXL4 (c.1750 T > C; p.Cys584Arg). Both patients presented with encephalomyopathy, lactic acidosis and cardiac hypertrophy, which are reported features of FBXL4 impairment. Remarkably, dichloroacetate (DCA) administration to the younger sibling improved metabolic acidosis and reversed cardiac hypertrophy. Characterization of FBXL4 patient fibroblasts revealed severe bioenergetic defects, mtDNA depletion, fragmentation of mitochondrial networks, and abnormalities in mtDNA nucleoids. These phenotypes, observed with other pathogenic FBXL4 variants, confirm the pathogenicity of the p.Cys584Arg variant. Although treating FBXL4 fibroblasts with DCA improved extracellular acidification, in line with reduced lactate levels in patients, DCA treatment did not improve any of the other mitochondrial functions. Nonetheless, we highlight DCA as a potentially effective drug for the management of elevated lactate and cardiomyopathy in patients with pathogenic FBXL4 variants. Finally, as the exact mechanism through which FBXL4 mutations lead to mtDNA depletion was unknown, we tested the hypothesis that FBXL4 promotes mitochondrial fusion. Using a photo-activatable GFP fusion assay, we found reduced mitochondrial fusion rates in cells harbouring a pathogenic FBXL4 variant. Meanwhile, overexpression of wildtype FBXL4, but not the p.Cys584Arg variant, promoted mitochondrial hyperfusion. Thus, we have uncovered a novel function for FBXL4 in promoting mitochondrial fusion, providing important mechanistic insights into the pathogenic mechanism underlying FBXL4 dysfunction.
Collapse
Affiliation(s)
- Rasha Sabouny
- Department of Biochemistry & Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada.
| | - Rachel Wong
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Laurie Lee-Glover
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Steven C Greenway
- Department of Biochemistry & Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Department of Pediatrics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Department of Cardiac Sciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada; Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada
| | - David S Sinasac
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | | | - Aneal Khan
- Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Department of Pediatrics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Timothy E Shutt
- Department of Biochemistry & Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Department of Medical Genetics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.
| |
Collapse
|
15
|
Rodríguez-Nuevo A, Díaz-Ramos A, Noguera E, Díaz-Sáez F, Duran X, Muñoz JP, Romero M, Plana N, Sebastián D, Tezze C, Romanello V, Ribas F, Seco J, Planet E, Doctrow SR, González J, Borràs M, Liesa M, Palacín M, Vendrell J, Villarroya F, Sandri M, Shirihai O, Zorzano A. Mitochondrial DNA and TLR9 drive muscle inflammation upon Opa1 deficiency. EMBO J 2018; 37:embj.201796553. [PMID: 29632021 DOI: 10.15252/embj.201796553] [Citation(s) in RCA: 119] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 03/07/2018] [Accepted: 03/08/2018] [Indexed: 01/04/2023] Open
Abstract
Opa1 participates in inner mitochondrial membrane fusion and cristae morphogenesis. Here, we show that muscle-specific Opa1 ablation causes reduced muscle fiber size, dysfunctional mitochondria, enhanced Fgf21, and muscle inflammation characterized by NF-κB activation, and enhanced expression of pro-inflammatory genes. Chronic sodium salicylate treatment ameliorated muscle alterations and reduced the muscle expression of Fgf21. Muscle inflammation was an early event during the progression of the disease and occurred before macrophage infiltration, indicating that it is a primary response to Opa1 deficiency. Moreover, Opa1 repression in muscle cells also resulted in NF-κB activation and inflammation in the absence of necrosis and/or apoptosis, thereby revealing that the activation is a cell-autonomous process and independent of cell death. The effects of Opa1 deficiency on the expression NF-κB target genes and inflammation were absent upon mitochondrial DNA depletion. Under Opa1 deficiency, blockage or repression of TLR9 prevented NF-κB activation and inflammation. Taken together, our results reveal that Opa1 deficiency in muscle causes initial mitochondrial alterations that lead to TLR9 activation, and inflammation, which contributes to enhanced Fgf21 expression and to growth impairment.
Collapse
Affiliation(s)
- Aida Rodríguez-Nuevo
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain.,Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.,CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
| | - Angels Díaz-Ramos
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain.,Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.,CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
| | - Eduard Noguera
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain.,Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.,CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
| | - Francisco Díaz-Sáez
- Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
| | - Xavier Duran
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain.,Hospital Universitari de Tarragona Joan XXIII-IISPV, Facultat de Medicina, Universitat Rovira i Virgili, Tarragona, Spain
| | - Juan Pablo Muñoz
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain.,Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.,CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
| | - Montserrat Romero
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain.,Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.,CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
| | - Natàlia Plana
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain.,Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.,CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
| | - David Sebastián
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain.,Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.,CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
| | | | | | - Francesc Ribas
- Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.,CIBER Fisiopatologia de la Obesidad y Nutricion, Instituto de Salud Carlos III, Barcelona, Spain
| | - Jordi Seco
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain.,Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.,CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
| | - Evarist Planet
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain
| | - Susan R Doctrow
- Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Javier González
- Experimental Toxicology and Ecotoxicology Unit (CERETOX), Barcelona Science Park, Barcelona, Spain
| | - Miquel Borràs
- Experimental Toxicology and Ecotoxicology Unit (CERETOX), Barcelona Science Park, Barcelona, Spain
| | - Marc Liesa
- Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, UCLA David Geffen School of Medicine, Los Angeles, CA, USA
| | - Manuel Palacín
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain.,Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.,CIBER de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Barcelona, Spain
| | - Joan Vendrell
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain.,Hospital Universitari de Tarragona Joan XXIII-IISPV, Facultat de Medicina, Universitat Rovira i Virgili, Tarragona, Spain
| | - Francesc Villarroya
- Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.,CIBER Fisiopatologia de la Obesidad y Nutricion, Instituto de Salud Carlos III, Barcelona, Spain
| | - Marco Sandri
- Venetian Institute of Molecular Medicine, Padova, Italy
| | - Orian Shirihai
- Department of Medicine, Boston University School of Medicine, Boston, MA, USA.,Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, UCLA David Geffen School of Medicine, Los Angeles, CA, USA
| | - Antonio Zorzano
- Institute for Research in Biomedicine (IRB Barcelona), Barcelona, Spain .,Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.,CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III, Madrid, Spain
| |
Collapse
|
16
|
Singh M, Tyagi SC. Genes and genetics in eye diseases: a genomic medicine approach for investigating hereditary and inflammatory ocular disorders. Int J Ophthalmol 2018; 11:117-134. [PMID: 29376001 DOI: 10.18240/ijo.2018.01.20] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 10/31/2017] [Indexed: 12/27/2022] Open
Abstract
Past 25y have witnessed an exponential increase in knowledge and understanding of ocular diseases and their respective genetic underpinnings. As a result, scientists have mapped many genes and their variants that can influence vision and health of our eyes. Based on these findings, it is becoming clear that an early diagnosis employing genetic testing can help evaluate patients' conditions for instituting treatment plan(s) and follow-up care to avoid vision complications later. For example, knowing family history becomes crucial for inherited eye diseases as it can benefit members in family who may have similar eye diseases or predispositions. Therefore, gathering information from an elaborate examination along with complete assessment of past medical illness by ophthalmologists followed by consultation with geneticists can help create a roadmap for making diagnosis and treatment precise and beneficial. In this review, we present an update on ocular genomic medicine that we believe has tremendous potential towards unraveling genetic implications in ocular diseases and patients' susceptibilities. We also discuss translational aspects of genetic ophthalmology and genome engineering that may help advance molecular diagnostics and therapeutics.
Collapse
Affiliation(s)
- Mahavir Singh
- Eye and Vision Science Laboratory, Department of Physiology, University of Louisville School of Medicine, Louisville, Kentucky 40202, USA
| | - Suresh C Tyagi
- Eye and Vision Science Laboratory, Department of Physiology, University of Louisville School of Medicine, Louisville, Kentucky 40202, USA
| |
Collapse
|
17
|
Caporali L, Maresca A, Capristo M, Del Dotto V, Tagliavini F, Valentino ML, La Morgia C, Carelli V. Incomplete penetrance in mitochondrial optic neuropathies. Mitochondrion 2017; 36:130-137. [PMID: 28716668 DOI: 10.1016/j.mito.2017.07.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 06/27/2017] [Accepted: 07/13/2017] [Indexed: 01/06/2023]
Abstract
Incomplete penetrance characterizes the two most frequent inherited optic neuropathies, Leber's Hereditary Optic Neuropathy (LHON) and dominant optic atrophy (DOA), due to genetic errors in the mitochondrial DNA (mtDNA) and the nuclear DNA (nDNA), respectively. For LHON, compelling evidence has accumulated on the complex interplay of mtDNA haplogroups and environmental interacting factors, whereas the nDNA remains essentially non informative. However, a compensatory mechanism of activated mitochondrial biogenesis and increased mtDNA copy number, possibly driven by a permissive nDNA background, is documented in LHON; when successful it maintains unaffected the mutation carriers, but in some individuals it might be hampered by tobacco smoking or other environmental factors, resulting in disease onset. In females, mitochondrial biogenesis is promoted and maintained within the compensatory range by estrogens, partially explaining the gender bias in LHON. Concerning DOA, none of the above mechanisms has been fully explored, thus mtDNA haplogroups, environmental factors such as tobacco and alcohol, and further nDNA variants may all participate as protective factors or, on the contrary, favor disease expression and severity. Next generation sequencing, complemented by transcriptomics and proteomics, may provide some answers in the next future, even if the multifactorial model that seems to apply to incomplete penetrance in mitochondrial optic neuropathies remains problematic, and careful stratification of patients will play a key role for data interpretation. The deep understanding of which factors impinge on incomplete penetrance may shed light on the pathogenic mechanisms leading to optic nerve atrophy, on their possible compensation and, thus, on development of therapeutic strategies.
Collapse
Affiliation(s)
- Leonardo Caporali
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy
| | - Alessandra Maresca
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy
| | | | - Valentina Del Dotto
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy
| | - Francesca Tagliavini
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy
| | - Maria Lucia Valentino
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy; Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy
| | - Chiara La Morgia
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy; Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy
| | - Valerio Carelli
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy; Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy.
| |
Collapse
|
18
|
Liskova P, Tesarova M, Dudakova L, Svecova S, Kolarova H, Honzik T, Seto S, Votruba M. OPA1 analysis in an international series of probands with bilateral optic atrophy. Acta Ophthalmol 2017; 95:363-369. [PMID: 27860320 DOI: 10.1111/aos.13285] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 09/02/2016] [Indexed: 01/16/2023]
Abstract
PURPOSE To determine the molecular genetic cause in previously unreported probands with optic atrophy from the United Kingdom, Czech Republic and Canada. METHODS OPA1 coding regions and flanking intronic sequences were screened by direct sequencing in 82 probands referred with a diagnosis of bilateral optic atrophy. Detected rare variants were assessed for pathogenicity by in silico analysis. Segregation of the identified variants was performed in available first degree relatives. RESULTS A total of 29 heterozygous mutations evaluated as pathogenic were identified in 42 probands, of these seven were novel. In two probands, only variants of unknown significance were found. 76% of pathogenic mutations observed in 30 (71%) of 42 probands were evaluated to lead to unstable transcripts resulting in haploinsufficiency. Three probands with the following disease-causing mutations c.1230+1G>A, c.1367G>A and c.2965dup were documented to suffer from hearing loss and/or neurological impairment. CONCLUSIONS OPA1 gene screening in patients with bilateral optic atrophy is an important part of clinical evaluation as it may establish correct clinical diagnosis. Our study expands the spectrum of OPA1 mutations causing dominant optic atrophy and supports the fact that haploinsufficiency is the most common disease mechanism.
Collapse
Affiliation(s)
- Petra Liskova
- Institute of Inherited Metabolic Disorders; First Faculty of Medicine; Charles University and General University Hospital in Prague; Prague Czech Republic
- Department of Ophthalmology; First Faculty of Medicine; Charles University and General University Hospital in Prague; Prague Czech Republic
| | - Marketa Tesarova
- Department of Paediatrics and Adolescent Medicine; First Faculty of Medicine; Charles University and General University Hospital in Prague; Prague Czech Republic
| | - Lubica Dudakova
- Institute of Inherited Metabolic Disorders; First Faculty of Medicine; Charles University and General University Hospital in Prague; Prague Czech Republic
| | - Stepanka Svecova
- Department of Paediatrics and Adolescent Medicine; First Faculty of Medicine; Charles University and General University Hospital in Prague; Prague Czech Republic
| | - Hana Kolarova
- Department of Paediatrics and Adolescent Medicine; First Faculty of Medicine; Charles University and General University Hospital in Prague; Prague Czech Republic
| | - Tomas Honzik
- Department of Paediatrics and Adolescent Medicine; First Faculty of Medicine; Charles University and General University Hospital in Prague; Prague Czech Republic
| | - Sharon Seto
- Cardiff Eye Unit; University Hospital of Wales; Cardiff UK
- School of Optometry & Vision Sciences; Cardiff University; Cardiff UK
| | - Marcela Votruba
- Cardiff Eye Unit; University Hospital of Wales; Cardiff UK
- School of Optometry & Vision Sciences; Cardiff University; Cardiff UK
| |
Collapse
|
19
|
Decreased Integrity, Content, and Increased Transcript Level of Mitochondrial DNA Are Associated with Keratoconus. PLoS One 2016; 11:e0165580. [PMID: 27783701 PMCID: PMC5081165 DOI: 10.1371/journal.pone.0165580] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 10/16/2016] [Indexed: 01/01/2023] Open
Abstract
Oxidative stress may play an important role in the pathogenesis of keratoconus (KC). Mitochondrial DNA (mtDNA) is involved in mitochondrial function, and the mtDNA content, integrity, and transcript level may affect the generation of reactive oxygen species (ROS) and be involved in the pathogenesis of KC. We designed a case-control study to research the relationship between KC and mtDNA integrity, content and transcription. One-hundred ninety-eight KC corneas and 106 normal corneas from Chinese patients were studied. Quantitative real-time PCR was used to measure the relative mtDNA content, transcript levels of mtDNA and related genes. Long-extension PCR was used to detect mtDNA damage. ROS, mitochondrial membrane potential and ATP were measured by respective assay kit, and Mito-Tracker Green was used to label the mitochondria. The relative mtDNA content of KC corneas was significantly lower than that of normal corneas (P = 9.19×10−24), possibly due to decreased expression of the mitochondrial transcription factor A (TFAM) gene (P = 3.26×10−3). In contrast, the transcript levels of mtDNA genes were significantly increased in KC corneas compared with normal corneas (NADH dehydrogenase subunit 1 [ND1]: P = 1.79×10−3; cytochrome c oxidase subunit 1 [COX1]: P = 1.54×10−3; NADH dehydrogenase subunit 1, [ND6]: P = 4.62×10−3). The latter may be the result of increased expression levels of mtDNA transcription-related genes mitochondrial RNA polymerase (POLRMT) (P = 2.55×10−4) and transcription factor B2 mitochondrial (TFB2M) (P = 7.88×10−5). KC corneas also had increased mtDNA damage (P = 3.63×10−10), higher ROS levels, and lower mitochondrial membrane potential and ATP levels compared with normal corneas. Decreased integrity, content and increased transcript level of mtDNA are associated with KC. These changes may affect the generation of ROS and play a role in the pathogenesis of KC.
Collapse
|
20
|
Mitochondrial role in adaptive response to stress conditions in preeclampsia. Sci Rep 2016; 6:32410. [PMID: 27573305 PMCID: PMC5004102 DOI: 10.1038/srep32410] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 08/09/2016] [Indexed: 01/12/2023] Open
Abstract
Preeclampsia (PE) is a pregnancy-specific syndrome, characterized in general by hypertension with proteinuria or other systemic disturbances. PE is the major cause of maternal and fetal morbidity and mortality worldwide. However, the etiology of PE still remains unclear. Our study involved 38 patients: 14 with uncomplicated pregnancy; 13 with early-onset PE (eoPE); and 11 with late-onset PE (loPE). We characterized the immunophenotype of cells isolated from the placenta and all biopsy samples were stained positive for Cytokeratin 7, SOX2, Nestin, Vimentin, and CD44. We obtained a significant increase in OPA1 mRNA and protein expression in the eoPE placentas. Moreover, TFAM expression was down-regulated in comparison to the control (p < 0.01). Mitochondrial DNA copy number in eoPE placentas was significantly higher than in samples from normal pregnancies. We observed an increase of maximum coupled state 3 respiration rate in mitochondria isolated from the placenta in the presence of complex I substrates in the eoPE group and an increase of P/O ratio, citrate synthase activity and decrease of Ca(2+)-induced depolarization rate in both PE groups. Our results suggest an essential role of mitochondrial activity changes in an adaptive response to the development of PE.
Collapse
|
21
|
Bertholet AM, Delerue T, Millet AM, Moulis MF, David C, Daloyau M, Arnauné-Pelloquin L, Davezac N, Mils V, Miquel MC, Rojo M, Belenguer P. Mitochondrial fusion/fission dynamics in neurodegeneration and neuronal plasticity. Neurobiol Dis 2015; 90:3-19. [PMID: 26494254 DOI: 10.1016/j.nbd.2015.10.011] [Citation(s) in RCA: 255] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 09/16/2015] [Accepted: 10/13/2015] [Indexed: 12/17/2022] Open
Abstract
Mitochondria are dynamic organelles that continually move, fuse and divide. The dynamic balance of fusion and fission of mitochondria determines their morphology and allows their immediate adaptation to energetic needs, keeps mitochondria in good health by restoring or removing damaged organelles or precipitates cells in apoptosis in cases of severe defects. Mitochondrial fusion and fission are essential in mammals and their disturbances are associated with several diseases. However, while mitochondrial fusion/fission dynamics, and the proteins that control these processes, are ubiquitous, associated diseases are primarily neurological disorders. Accordingly, inactivation of the main actors of mitochondrial fusion/fission dynamics is associated with defects in neuronal development, plasticity and functioning, both ex vivo and in vivo. Here, we present the central actors of mitochondrial fusion and fission and review the role of mitochondrial dynamics in neuronal physiology and pathophysiology. Particular emphasis is placed on the three main actors of these processes i.e. DRP1,MFN1-2, and OPA1 as well as on GDAP1, a protein of the mitochondrial outer membrane preferentially expressed in neurons. This article is part of a Special Issue entitled: Mitochondria & Brain.
Collapse
Affiliation(s)
- A M Bertholet
- Université de Toulouse, Centre de Biologie du Développement, CNRS, UMR5547/Université Paul Sabatier, Toulouse, France; CNRS, Centre de Biologie du Développement, UMR5547/Université Paul Sabatier, Toulouse, France
| | - T Delerue
- Université de Toulouse, Centre de Biologie du Développement, CNRS, UMR5547/Université Paul Sabatier, Toulouse, France; CNRS, Centre de Biologie du Développement, UMR5547/Université Paul Sabatier, Toulouse, France
| | - A M Millet
- Université de Toulouse, Centre de Biologie du Développement, CNRS, UMR5547/Université Paul Sabatier, Toulouse, France; CNRS, Centre de Biologie du Développement, UMR5547/Université Paul Sabatier, Toulouse, France
| | - M F Moulis
- Université de Toulouse, Centre de Biologie du Développement, CNRS, UMR5547/Université Paul Sabatier, Toulouse, France; CNRS, Centre de Biologie du Développement, UMR5547/Université Paul Sabatier, Toulouse, France
| | - C David
- CNRS, Institut de Biochimie et Génétique Cellulaires (IBGC), UMR5095, Bordeaux, France; Université de Bordeaux, Institut de Biochimie et Génétique Cellulaires (IBGC), UMR5095, Bordeaux, France
| | - M Daloyau
- Université de Toulouse, Centre de Biologie du Développement, CNRS, UMR5547/Université Paul Sabatier, Toulouse, France; CNRS, Centre de Biologie du Développement, UMR5547/Université Paul Sabatier, Toulouse, France
| | - L Arnauné-Pelloquin
- Université de Toulouse, Centre de Biologie du Développement, CNRS, UMR5547/Université Paul Sabatier, Toulouse, France; CNRS, Centre de Biologie du Développement, UMR5547/Université Paul Sabatier, Toulouse, France
| | - N Davezac
- Université de Toulouse, Centre de Biologie du Développement, CNRS, UMR5547/Université Paul Sabatier, Toulouse, France; CNRS, Centre de Biologie du Développement, UMR5547/Université Paul Sabatier, Toulouse, France
| | - V Mils
- Université de Toulouse, Centre de Biologie du Développement, CNRS, UMR5547/Université Paul Sabatier, Toulouse, France; CNRS, Centre de Biologie du Développement, UMR5547/Université Paul Sabatier, Toulouse, France
| | - M C Miquel
- Université de Toulouse, Centre de Biologie du Développement, CNRS, UMR5547/Université Paul Sabatier, Toulouse, France; CNRS, Centre de Biologie du Développement, UMR5547/Université Paul Sabatier, Toulouse, France
| | - M Rojo
- CNRS, Institut de Biochimie et Génétique Cellulaires (IBGC), UMR5095, Bordeaux, France; Université de Bordeaux, Institut de Biochimie et Génétique Cellulaires (IBGC), UMR5095, Bordeaux, France.
| | - P Belenguer
- Université de Toulouse, Centre de Biologie du Développement, CNRS, UMR5547/Université Paul Sabatier, Toulouse, France; CNRS, Centre de Biologie du Développement, UMR5547/Université Paul Sabatier, Toulouse, France.
| |
Collapse
|
22
|
Zorzano A, Claret M. Implications of mitochondrial dynamics on neurodegeneration and on hypothalamic dysfunction. Front Aging Neurosci 2015; 7:101. [PMID: 26113818 PMCID: PMC4461829 DOI: 10.3389/fnagi.2015.00101] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Accepted: 05/11/2015] [Indexed: 01/10/2023] Open
Abstract
Mitochondrial dynamics is a term that encompasses the movement of mitochondria along the cytoskeleton, regulation of their architecture, and connectivity mediated by tethering and fusion/fission. The importance of these events in cell physiology and pathology has been partially unraveled with the identification of the genes responsible for the catalysis of mitochondrial fusion and fission. Mutations in two mitochondrial fusion genes (MFN2 and OPA1) cause neurodegenerative diseases, namely Charcot-Marie Tooth type 2A and autosomal dominant optic atrophy (ADOA). Alterations in mitochondrial dynamics may be involved in the pathophysiology of prevalent neurodegenerative conditions. Moreover, impairment of the activity of mitochondrial fusion proteins dysregulates the function of hypothalamic neurons, leading to alterations in food intake and in energy homeostasis. Here we review selected findings in the field of mitochondrial dynamics and their relevance for neurodegeneration and hypothalamic dysfunction.
Collapse
Affiliation(s)
- Antonio Zorzano
- Molecular Medicine Program, Institute of Research in Biomedicine (IRB Barcelona) Barcelona, Spain ; Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona Barcelona, Spain ; CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Instituto de Salud Carlos III Barcelona, Spain
| | - Marc Claret
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Instituto de Salud Carlos III Barcelona, Spain ; Diabetes and Obesity Research Laboratory, Institut d'Investigacions Biomèdiques August Pi i Sunyer Barcelona, Spain
| |
Collapse
|
23
|
Szklarczyk R, Nooteboom M, Osiewacz HD. Control of mitochondrial integrity in ageing and disease. Philos Trans R Soc Lond B Biol Sci 2015; 369:20130439. [PMID: 24864310 DOI: 10.1098/rstb.2013.0439] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Various molecular and cellular pathways are active in eukaryotes to control the quality and integrity of mitochondria. These pathways are involved in keeping a 'healthy' population of this essential organelle during the lifetime of the organism. Quality control (QC) systems counteract processes that lead to organellar dysfunction manifesting as degenerative diseases and ageing. We discuss disease- and ageing-related pathways involved in mitochondrial QC: mtDNA repair and reorganization, regeneration of oxidized amino acids, refolding and degradation of severely damaged proteins, degradation of whole mitochondria by mitophagy and finally programmed cell death. The control of the integrity of mtDNA and regulation of its expression is essential to remodel single proteins as well as mitochondrial complexes that determine mitochondrial functions. The redundancy of components, such as proteases, and the hierarchies of the QC raise questions about crosstalk between systems and their precise regulation. The understanding of the underlying mechanisms on the genomic, proteomic, organellar and cellular levels holds the key for the development of interventions for mitochondrial dysfunctions, degenerative processes, ageing and age-related diseases resulting from impairments of mitochondria.
Collapse
Affiliation(s)
- Radek Szklarczyk
- Centre for Molecular and Biomolecular Informatics, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands Department of Clinical Genetics, Unit Clinical Genomics, Maastricht University Medical Centre, 6200 MD Maastricht, The Netherlands
| | - Marco Nooteboom
- Department of Biochemistry (286), Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, 6500 HB Nijmegen, The Netherlands
| | - Heinz D Osiewacz
- Faculty for Biosciences and Cluster of Excellence 'Macromolecular Complexes', Goethe University, Molecular Developmental Biology, 60438 Frankfurt am Main, Germany
| |
Collapse
|
24
|
Alavi MV, Fuhrmann N. Dominant optic atrophy, OPA1, and mitochondrial quality control: understanding mitochondrial network dynamics. Mol Neurodegener 2013; 8:32. [PMID: 24067127 PMCID: PMC3856479 DOI: 10.1186/1750-1326-8-32] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 09/16/2013] [Indexed: 12/13/2022] Open
Abstract
Mitochondrial quality control is fundamental to all neurodegenerative diseases, including the most prominent ones, Alzheimer’s Disease and Parkinsonism. It is accomplished by mitochondrial network dynamics – continuous fission and fusion of mitochondria. Mitochondrial fission is facilitated by DRP1, while MFN1 and MFN2 on the mitochondrial outer membrane and OPA1 on the mitochondrial inner membrane are essential for mitochondrial fusion. Mitochondrial network dynamics are regulated in highly sophisticated ways by various different posttranslational modifications, such as phosphorylation, ubiquitination, and proteolytic processing of their key-proteins. By this, mitochondria process a wide range of different intracellular and extracellular parameters in order to adapt mitochondrial function to actual energetic and metabolic demands of the host cell, attenuate mitochondrial damage, recycle dysfunctional mitochondria via the mitochondrial autophagy pathway, or arrange for the recycling of the complete host cell by apoptosis. Most of the genes coding for proteins involved in this process have been associated with neurodegenerative diseases. Mutations in one of these genes are associated with a neurodegenerative disease that originally was described to affect retinal ganglion cells only. Since more and more evidence shows that other cell types are affected as well, we would like to discuss the pathology of dominant optic atrophy, which is caused by heterozygous sequence variants in OPA1, in the light of the current view on OPA1 protein function in mitochondrial quality control, in particular on its function in mitochondrial fusion and cytochrome C release. We think OPA1 is a good example to understand the molecular basis for mitochondrial network dynamics.
Collapse
Affiliation(s)
- Marcel V Alavi
- Department of Ophthalmology, University of California, San Francisco, 10 Koret Way, 94143-0730 San Francisco, CA, USA.
| | | |
Collapse
|
25
|
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: 18] [Impact Index Per Article: 1.6] [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
|
26
|
Paracha UZ, Fatima K, Alqahtani M, Chaudhary A, Abuzenadah A, Damanhouri G, Qadri I. Oxidative stress and hepatitis C virus. Virol J 2013; 10:251. [PMID: 23923986 PMCID: PMC3751576 DOI: 10.1186/1743-422x-10-251] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 07/31/2013] [Indexed: 02/08/2023] Open
Abstract
The disproportionate imbalance between the systemic manifestation of reactive oxygen species and body’s ability to detoxify the reactive intermediates is referred to as oxidative stress. Several biological processes as well as infectious agents, physiological or environmental stress, and perturbed antioxidant response can promote oxidative stress. Oxidative stress usually happens when cells are exposed to more electrically charged reactive oxygen species (ROS) such as H2O2 or O2-. The cells’ ability to handle such pro-oxidant species is impeded by viral infections particularly within liver that plays an important role in metabolism and detoxification of harmful substances. During liver diseases (such as hepatocellular or cholestatic problems), the produced ROS are involved in transcriptional activation of a large number of cytokines and growth factors, and continued production of ROS and Reactive Nitrogen Species (RNS) feed into the vicious cycle. Many human viruses like HCV are evolved to manipulate this delicate pro- and antioxidant balance; thus generating the sustainable oxidative stress that not only causes hepatic damage but also stimulates the processes to reduce treatment of damage. In this review article, the oxidant and antioxidant pathways that are perturbed by HCV genes are discussed. In the first line of risk, the pathways of lipid metabolism present a clear danger in accumulation of viral induced ROS. Viral infection leads to decrease in cellular concentrations of glutathione (GSH) resulting in oxidation of important components of cells such as proteins, DNA and lipids as well as double strand breakage of DNA. These disorders have the tendency to lead the cells toward cirrhosis and hepatocellular carcinoma in adults due to constant insult. We have highlighted the importance of such pathways and revealed differences in the extent of oxidative stress caused by HCV infection.
Collapse
|
27
|
Rahn JJ, Stackley KD, Chan SSL. Opa1 is required for proper mitochondrial metabolism in early development. PLoS One 2013; 8:e59218. [PMID: 23516612 PMCID: PMC3597633 DOI: 10.1371/journal.pone.0059218] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 02/12/2013] [Indexed: 12/03/2022] Open
Abstract
Opa1 catalyzes fusion of inner mitochondrial membranes and formation of the cristae. OPA1 mutations in humans lead to autosomal dominant optic atrophy. OPA1 knockout mice lose viability around embryonic day 9 from unknown reasons, indicating that OPA1 is essential for embryonic development. Zebrafish are an attractive model for studying vertebrate development and have been used for many years to describe developmental events that are difficult or impractical to view in mammalian models. In this study, Opa1 was successfully depleted in zebrafish embryos using antisense morpholinos, which resulted in disrupted mitochondrial morphology. Phenotypically, these embryos exhibited abnormal blood circulation and heart defects, as well as small eyes and small pectoral fin buds. Additionally, startle response was reduced and locomotor activity was impaired. Furthermore, Opa1 depletion caused bioenergetic defects, without impairing mitochondrial efficiency. In response to mitochondrial dysfunction, a transient upregulation of the master regulator of mitochondrial biogenesis, pgc1a, was observed. These results not only reveal a new Opa1-associated phenotype in a vertebrate model system, but also further elucidates the absolute requirement of Opa1 for successful vertebrate development.
Collapse
Affiliation(s)
- Jennifer J Rahn
- Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | | | | |
Collapse
|
28
|
Belenguer P, Pellegrini L. The dynamin GTPase OPA1: More than mitochondria? BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:176-83. [DOI: 10.1016/j.bbamcr.2012.08.004] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 08/01/2012] [Accepted: 08/03/2012] [Indexed: 12/24/2022]
|
29
|
Malik AN, Czajka A. Is mitochondrial DNA content a potential biomarker of mitochondrial dysfunction? Mitochondrion 2012; 13:481-92. [PMID: 23085537 DOI: 10.1016/j.mito.2012.10.011] [Citation(s) in RCA: 327] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 10/10/2012] [Accepted: 10/11/2012] [Indexed: 12/17/2022]
Abstract
Mitochondrial dysfunction is central to numerous diseases of oxidative stress. Changes in mitochondrial DNA (MtDNA) content, often measured as mitochondrial genome to nuclear genome ratio (Mt/N) using real time quantitative PCR, have been reported in a broad range of human diseases, such as diabetes and its complications, obesity, cancer, HIV complications, and ageing. We propose the hypothesis that MtDNA content in body fluids and tissues could be a biomarker of mitochondrial dysfunction and review the evidence supporting this theory. Increased reactive oxygen species resulting from an external trigger such as hyperglycaemia or increased fat in conditions of oxidative stress could lead to enhanced mitochondrial biogenesis, and increased Mt/N. Altered MtDNA levels may contribute to enhanced oxidative stress and inflammation and could play a pathogenic role in mitochondrial dysfunction and disease. Changes in Mt/N are detectable in circulating cells such as peripheral blood mononuclear cells and these could be used as surrogate to predict global changes in tissues and organs. We review a large number of studies reporting changes in MtDNA levels in body fluids such as circulating blood cells, cell free serum, saliva, sperm, and cerebrospinal fluid as well as in tumour and normal tissue samples. However, the data are often conflicting as the current methodology used to measure Mt/N can give false results because of one or more of the following reasons (1) use of mitochondrial primers which co-amplify nuclear pseudogenes (2) use of nuclear genes which are variable and/or duplicated in numerous locations (3) a dilution bias caused by the differing genome sizes of the mitochondrial and nuclear genome and (4) template preparation protocols which affect the yields of nuclear and mitochondrial genomes. Development of robust and reproducible methodology is needed to test the hypothesis that MtDNA content in body fluids is biomarker of mitochondrial dysfunction.
Collapse
Affiliation(s)
- Afshan N Malik
- Diabetes Research Group, Division of Diabetes and Nutritional Sciences, School of Medicine, King's college London, London, UK.
| | | |
Collapse
|
30
|
Yen HH, Shih KL, Lin TT, Su WW, Soon MS, Liu CS. Decreased mitochondrial deoxyribonucleic acid and increased oxidative damage in chronic hepatitis C. World J Gastroenterol 2012; 18:5084-9. [PMID: 23049218 PMCID: PMC3460336 DOI: 10.3748/wjg.v18.i36.5084] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2012] [Revised: 05/09/2012] [Accepted: 05/13/2012] [Indexed: 02/06/2023] Open
Abstract
AIM: To determine whether alteration of the mitochondria DNA (mtDNA) copy number and its oxidative damage index (mtDNA∆CT) can be detected by analysis of peripheral blood cells in hepatitis C virus (HCV)-infected patients.
METHODS: This study enrolled two groups of patients aged 40-60 years: a control group and an HCV-infected group in Department of Gastroenterology and Hepatology in Changhua Christian Hospital. Patients with co-infection with hepatitis B virus or human immunodeficiency virus, autoimmune disease, malignant neoplasia, pregnancy, thyroid disease, or alcohol consumption > 40 g/d were excluded. HCV-infected patients who met the following criteria were included: (1) positive HCV antibodies for > 6 mo; (2) alanine aminotransferase (ALT) levels more than twice the upper limit of normal on at least two occasions during the past 6 mo; and (3) histological fibrosis stage higher than F1. The mtDNA copy number and oxidative damage index of HCV mtDNA (mtDNA∆CT) were measured in peripheral blood leukocytes. The association between mtDNA copy number and mtDNA∆CT was further analyzed using clinical data.
RESULTS: Forty-seven normal controls (male/female: 26/21, mean age 50.51 ± 6.15 years) and 132 HCV-infected patients (male/female: 76/61, mean age 51.65 ± 5.50 years) were included in the study. The genotypes of HCV-infected patients include type 1a (n = 3), type 1b (n = 83), type 2a (n = 32), and type 2b (n = 14). Liver fibrosis stages were distributed as follows: F1/F2/F3/F4 = 1/61/45/25 and activity scores were A0/A1/A2/A3 = 7/45/55/25. There were no age or gender differences between the two groups. HCV-infected patients had higher hepatitis activity (aspartate transaminase levels 108.77 ± 60.73 vs 23.19 ± 5.47, P < 0.01; ALT levels 168.69 ± 93.12 vs 23.15 ± 9.45, P < 0.01) and lower platelet count (170.40 ± 58.00 vs 251.24 ± 63.42, P < 0.01) than controls. The mtDNA copy number was lower in HCV-infected patients than in controls (173.49 vs 247.93, P < 0.05). The mtDNA∆CT was higher in HCV-infected patients than in controls (2.92 vs 0.64, P < 0.05). To clarify the clinical significance of these results in HCV-infected patients, their association with different clinical parameters among HCV-infected patients was analyzed. A negative association was found between mtDNA copy number and elevated aspartate transaminase levels (r = -0.17, P < 0.05). Changes in mtDNA copy number were not associated with HCV RNA levels, HCV genotypes, liver fibrosis severity, or inflammatory activity in the liver biopsy specimen. However, a correlation was observed between mtDNA∆CT and platelet count (r = -0.22, P < 0.01), HCV RNA level (r = 0.36, P < 0.01), and hepatitis activity (r = 0.20, P = 0.02). However, no difference in the change in mtDNA∆CT was observed between different fibrosis stages or HCV genotypes.
CONCLUSION: Oxidative stress and mtDNA damage are detectable in patient’s peripheral leukocytes. Increased leukocyte mtDNA∆CT correlates with higher HCV viremia, increased hepatitis activity, and lower platelet count.
Collapse
|
31
|
Sitarz KS, Almind GJ, Horvath R, Czermin B, Grønskov K, Pyle A, Taylor RW, Larsen M, Chinnery PF, Yu-Wai-Man P. OPA1 mutations induce mtDNA proliferation in leukocytes of patients with dominant optic atrophy. Neurology 2012; 79:1515-7. [PMID: 22993284 DOI: 10.1212/wnl.0b013e31826d5f60] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Kamil S Sitarz
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | | | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Zhang J, Yuan Y, Lin B, Feng H, Li Y, Dai X, Zhou H, Dong X, Liu XL, Guan MX. A novel OPA1 mutation in a Chinese family with autosomal dominant optic atrophy. Biochem Biophys Res Commun 2012; 419:670-5. [PMID: 22382025 DOI: 10.1016/j.bbrc.2012.02.073] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2012] [Accepted: 02/13/2012] [Indexed: 12/01/2022]
Abstract
A large four-generation Chinese family with autosomal dominant optic atrophy (ADOA) was investigated in the present study. Eight of the family members were affected in this pedigree. The affected family members exhibited early-onset and progressive visual impairment, resulting in mild to profound loss of visual acuity. The average age-at-onset was 15.9years. A new heterozygous mutation c.C1198G was identified by sequence analysis of the 12th exon of the OPA1 gene. This mutation resulted in a proline to alanine substitution at codon 400, which was located in an evolutionarily conserved region. This missense mutation in the GTPase domain was supposed to result in a loss of function for the encoded protein and act through a dominant negative effect. No other mutations associated with optic atrophy were found in our present study. The c.C1198G heterozygous mutation in the OPA1 gene may be a novel key pathogenic mutation in this pedigree with ADOA. Furthermore, additional nuclear modifier genes, environmental factors, and psychological factors may also contribute to the phenotypic variability of ADOA in this pedigree.
Collapse
Affiliation(s)
- Juanjuan Zhang
- School of Ophthalmology and Optometry, Wenzhou Medical College, Wenzhou 325027, Zhejiang, China
| | | | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Van Bergen NJ, Chakrabarti R, O’Neill EC, Crowston JG, Trounce IA. Mitochondrial disorders and the eye. Eye Brain 2011; 3:29-47. [PMID: 28539774 PMCID: PMC5436186 DOI: 10.2147/eb.s16192] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The clinical significance of disturbed mitochondrial function in the eye has emerged since mitochondrial DNA (mtDNA) mutation was described in Leber's hereditary optic neuropathy. The spectrum of mitochondrial dysfunction has become apparent through increased understanding of the contribution of nuclear and somatic mtDNA mutations to mitochondrial dynamics and function. Common ophthalmic manifestations of mitochondrial dysfunction include optic atrophy, pigmentary retinopathy, and ophthalmoplegia. The majority of patients with ocular manifestations of mitochondrial disease also have variable central and peripheral nervous system involvement. Mitochondrial dysfunction has recently been associated with age-related retinal disease including macular degeneration and glaucoma. Therefore, therapeutic targets directed at promoting mitochondrial biogenesis and function offer a potential to both preserve retinal function and attenuate neurodegenerative processes.
Collapse
Affiliation(s)
- Nicole J Van Bergen
- Centre for Eye Research Australia, Department of Ophthalmology, University of Melbourne, Victoria, Australia
| | - Rahul Chakrabarti
- Centre for Eye Research Australia, Department of Ophthalmology, University of Melbourne, Victoria, Australia
| | - Evelyn C O’Neill
- Centre for Eye Research Australia, Department of Ophthalmology, University of Melbourne, Victoria, Australia
| | - Jonathan G Crowston
- Centre for Eye Research Australia, Department of Ophthalmology, University of Melbourne, Victoria, Australia
| | - Ian A Trounce
- Centre for Eye Research Australia, Department of Ophthalmology, University of Melbourne, Victoria, Australia
| |
Collapse
|
34
|
Malik AN, Shahni R, Rodriguez-de-Ledesma A, Laftah A, Cunningham P. Mitochondrial DNA as a non-invasive biomarker: accurate quantification using real time quantitative PCR without co-amplification of pseudogenes and dilution bias. Biochem Biophys Res Commun 2011; 412:1-7. [PMID: 21703239 DOI: 10.1016/j.bbrc.2011.06.067] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Accepted: 06/08/2011] [Indexed: 02/07/2023]
Abstract
Circulating mitochondrial DNA (MtDNA) is a potential non-invasive biomarker of cellular mitochondrial dysfunction, the latter known to be central to a wide range of human diseases. Changes in MtDNA are usually determined by quantification of MtDNA relative to nuclear DNA (Mt/N) using real time quantitative PCR. We propose that the methodology for measuring Mt/N needs to be improved and we have identified that current methods have at least one of the following three problems: (1) As much of the mitochondrial genome is duplicated in the nuclear genome, many commonly used MtDNA primers co-amplify homologous pseudogenes found in the nuclear genome; (2) use of regions from genes such as β-actin and 18S rRNA which are repetitive and/or highly variable for qPCR of the nuclear genome leads to errors; and (3) the size difference of mitochondrial and nuclear genomes cause a "dilution bias" when template DNA is diluted. We describe a PCR-based method using unique regions in the human mitochondrial genome not duplicated in the nuclear genome; unique single copy region in the nuclear genome and template treatment to remove dilution bias, to accurately quantify MtDNA from human samples.
Collapse
Affiliation(s)
- Afshan N Malik
- King's College London, Diabetes Research Group, Division of Diabetes and Nutritional Sciences, School of Medicine, UK.
| | | | | | | | | |
Collapse
|
35
|
Makino A, Scott BT, Dillmann WH. Mitochondrial fragmentation and superoxide anion production in coronary endothelial cells from a mouse model of type 1 diabetes. Diabetologia 2010; 53:1783-94. [PMID: 20461356 PMCID: PMC2892085 DOI: 10.1007/s00125-010-1770-4] [Citation(s) in RCA: 175] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Accepted: 03/30/2010] [Indexed: 12/25/2022]
Abstract
AIMS/HYPOTHESIS Mitochondria frequently change their shapes by fusion and fission and these morphological dynamics play important roles in mitochondrial function and development as well as programmed cell death. The goal of this study is to investigate whether: (1) mitochondria in mouse coronary endothelial cells (MCECs) isolated from diabetic mice exhibit increased fragmentation; and (2) chronic treatment with a superoxide anion (O(2)(-)) scavenger has a beneficial effect on mitochondrial fragmentation in MCECs. METHODS MCECs were freshly isolated and lysed for protein measurement, or cultured to determine mitochondrial morphology and O(2)(-) production. For the ex vivo hyperglycaemia experiments, human coronary endothelial cells were used. RESULTS Elongated mitochondrial tubules were observed in MCECs isolated from control mice, whereas mitochondria in MCECs from diabetic mice exhibited augmented fragmentation. The level of optic atrophy 1 (OPA1) protein, which leads to mitochondrial fusion, was significantly decreased, while dynamin-related protein 1 (DRP1), which leads to mitochondrial fission, was significantly increased in MCECs from diabetic mice. Diabetic MCECs exhibited significantly higher O(2)(-) concentrations in cytosol and mitochondria than control MCECs. Administration of the O(2)(-) scavenger TEMPOL to diabetic mice for 4 weeks led to a significant decrease in mitochondrial fragmentation without altering the levels of OPA1 and DRP1 proteins in MCECs. High-glucose treatment for 24 h significantly induced mitochondrial fragmentation, which was restored by TEMPOL treatment. In addition, excess O(2)(-) production, either in cytosol or in mitochondria, significantly increased mitochondrial fragmentation. CONCLUSIONS/INTERPRETATION These data suggest that lowering the O(2)(-) concentration can restore the morphological change in mitochondria and may help improve mitochondrial function in diabetic MCECs.
Collapse
Affiliation(s)
- A. Makino
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, 9500 Gilman Drive, MC0618, La Jolla, CA 92093-0618 USA
| | - B. T. Scott
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, 9500 Gilman Drive, MC0618, La Jolla, CA 92093-0618 USA
| | - W. H. Dillmann
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, 9500 Gilman Drive, MC0618, La Jolla, CA 92093-0618 USA
| |
Collapse
|
36
|
Genetic variation in PARL influences mitochondrial content. Hum Genet 2009; 127:183-90. [PMID: 19862556 DOI: 10.1007/s00439-009-0756-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2009] [Accepted: 10/13/2009] [Indexed: 12/19/2022]
Abstract
Given their involvement in processes necessary for life, mitochondrial damage and subsequent dysfunction can lead to a wide range of human diseases. Previous studies of both animal models and humans have suggested that presenilins-associated rhomboid-like protein (PARL) is a key regulator of mitochondrial integrity and function, and plays a role in cellular apoptosis. As a surrogate measure of mitochondrial integrity, we previously measured mitochondrial content in a Caucasian population consisting of large extended pedigrees, with results highlighting a substantial genetic component to this trait. To assess the influence of variation in the PARL gene on mitochondrial content, we re-sequenced 6.5 kb of the gene, identifying 16 SNPs and genotyped these in 1,086 Caucasian individuals, distributed across 170 families. Statistical genetic analysis revealed that one promoter variant, T-191C, exhibited significant effects (after correction for multiple testing) on mitochondrial content levels. Comparison of the transcription factor binding characteristics of the T-191C promoter SNP by EMSA indicates preferential binding of nuclear factors to the T allele, suggesting functional variation in PARL expression. These results suggest that genetic variation within PARL influences mitochondrial abundance and integrity.
Collapse
|
37
|
Amati-Bonneau P, Milea D, Bonneau D, Chevrollier A, Ferré M, Guillet V, Gueguen N, Loiseau D, Crescenzo MAPD, Verny C, Procaccio V, Lenaers G, Reynier P. OPA1-associated disorders: Phenotypes and pathophysiology. Int J Biochem Cell Biol 2009; 41:1855-65. [DOI: 10.1016/j.biocel.2009.04.012] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2008] [Revised: 04/09/2009] [Accepted: 04/14/2009] [Indexed: 10/20/2022]
|
38
|
Artal-Sanz M, Tavernarakis N. Prohibitin and mitochondrial biology. Trends Endocrinol Metab 2009; 20:394-401. [PMID: 19733482 DOI: 10.1016/j.tem.2009.04.004] [Citation(s) in RCA: 215] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2009] [Revised: 04/12/2009] [Accepted: 04/14/2009] [Indexed: 12/15/2022]
Abstract
Prohibitins are ubiquitous, evolutionarily conserved proteins that are mainly localized in mitochondria. The mitochondrial prohibitin complex comprises two subunits, PHB1 and PHB2. These two proteins assemble into a ring-like macromolecular structure at the inner mitochondrial membrane and are implicated in diverse cellular processes: from mitochondrial biogenesis and function to cell death and replicative senescence. In humans, prohibitins have been associated with various types of cancer. While their biochemical function remains poorly understood, studies in organisms ranging from yeast to mammals have provided significant insights into the role of the prohibitin complex in mitochondrial biogenesis and metabolism. Here we review recent studies and discuss their implications for deciphering the function of prohibitins in mitochondria.
Collapse
Affiliation(s)
- Marta Artal-Sanz
- Instituto de Biomedicina de Valencia, CSIC, 46010 Valencia, Spain
| | | |
Collapse
|
39
|
Ugalde C, Morán M, Blázquez A, Arenas J, Martín MA. Mitochondrial Disorders Due to Nuclear OXPHOS Gene Defects. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 652:85-116. [DOI: 10.1007/978-90-481-2813-6_7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
|
40
|
Liesa M, Palacín M, Zorzano A. Mitochondrial dynamics in mammalian health and disease. Physiol Rev 2009; 89:799-845. [PMID: 19584314 DOI: 10.1152/physrev.00030.2008] [Citation(s) in RCA: 686] [Impact Index Per Article: 45.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The meaning of the word mitochondrion (from the Greek mitos, meaning thread, and chondros, grain) illustrates that the heterogeneity of mitochondrial morphology has been known since the first descriptions of this organelle. Such a heterogeneous morphology is explained by the dynamic nature of mitochondria. Mitochondrial dynamics is a concept that includes the movement of mitochondria along the cytoskeleton, the regulation of mitochondrial architecture (morphology and distribution), and connectivity mediated by tethering and fusion/fission events. The relevance of these events in mitochondrial and cell physiology has been partially unraveled after the identification of the genes responsible for mitochondrial fusion and fission. Furthermore, during the last decade, it has been identified that mutations in two mitochondrial fusion genes (MFN2 and OPA1) cause prevalent neurodegenerative diseases (Charcot-Marie Tooth type 2A and Kjer disease/autosomal dominant optic atrophy). In addition, other diseases such as type 2 diabetes or vascular proliferative disorders show impaired MFN2 expression. Altogether, these findings have established mitochondrial dynamics as a consolidated area in cellular physiology. Here we review the most significant findings in the field of mitochondrial dynamics in mammalian cells and their implication in human pathologies.
Collapse
Affiliation(s)
- Marc Liesa
- Institute for Research in Biomedicine (IRB Barcelona), CIBER de Diabetes y Enfermedades Metabólicas Asociadas, and Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, Barcelona 08028, Spain
| | | | | |
Collapse
|
41
|
Cartoni R, Martinou JC. Role of mitofusin 2 mutations in the physiopathology of Charcot-Marie-Tooth disease type 2A. Exp Neurol 2009; 218:268-73. [PMID: 19427854 DOI: 10.1016/j.expneurol.2009.05.003] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Revised: 04/29/2009] [Accepted: 05/02/2009] [Indexed: 01/12/2023]
Abstract
Charcot-Marie-Tooth disease (CMT) is the most common form of hereditary peripheral neuropathy. The main axonal form of CMT, CMT2A, preferentially affects peripheral neurons with the longest neurites. CMT2A has been recently linked to mutations in the mitofusin 2 (Mfn2) gene. Mfn2 participates in mitochondrial fusion a process that together with mitochondrial fission, contributes to mitochondrial morphology. Many hypotheses have been postulated to understand how mutations in Mfn2 lead to CMT2A. In this review, we will describe the physiological role of Mfn2, the pathophysiology of CMT2A and current hypotheses about the deleterious role of mutant Mfn2 in neuronal function.
Collapse
|
42
|
Carelli V, La Morgia C, Valentino ML, Barboni P, Ross-Cisneros FN, Sadun AA. Retinal ganglion cell neurodegeneration in mitochondrial inherited disorders. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:518-28. [DOI: 10.1016/j.bbabio.2009.02.024] [Citation(s) in RCA: 166] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2008] [Revised: 02/24/2009] [Accepted: 02/26/2009] [Indexed: 01/30/2023]
|
43
|
OPA1 functions in mitochondria and dysfunctions in optic nerve. Int J Biochem Cell Biol 2009; 41:1866-74. [PMID: 19389483 DOI: 10.1016/j.biocel.2009.04.013] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Revised: 04/11/2009] [Accepted: 04/14/2009] [Indexed: 11/23/2022]
Abstract
OPA1 is the major gene responsible for Dominant Optic Atrophy (DOA), a blinding disease that affects specifically the retinal ganglion cells (RGCs), which function consists in connecting the neuro-retina to the brain. OPA1 encodes an intra-mitochondrial dynamin, involved in inner membrane structures and ubiquitously expressed, raising the critical question of the origin of the disease pathophysiology. Here, we review the fundamental knowledge on OPA1 functions and regulations, highlighting their involvements in mitochondrial respiration, membrane dynamic and apoptosis. In light of these functions, we then describe the remarkable RGC mitochondrial network physiology and analyse data collected from animal models expressing OPA1 mutations. If, to date RGC mitochondria does not present any peculiarity at the molecular level, they represent possible targets of numerous assaults, like light, pressure, oxidative stress and energetic impairment, which jeopardize their function and survival, as observed in OPA1 mouse models. Although fascinating fields of investigation are still to be addressed on OPA1 functions and on DOA pathophysiology, we have reached a conspicuous state of knowledge with pertinent cell and animal models, from which therapeutic trials can be initiated and deeply evaluated.
Collapse
|
44
|
Tang S, Le PK, Tse S, Wallace DC, Huang T. Heterozygous mutation of Opa1 in Drosophila shortens lifespan mediated through increased reactive oxygen species production. PLoS One 2009; 4:e4492. [PMID: 19221591 PMCID: PMC2637430 DOI: 10.1371/journal.pone.0004492] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2008] [Accepted: 12/19/2008] [Indexed: 12/03/2022] Open
Abstract
Optic atrophy 1 (OPA1) is a dynamin-like GTPase located in the inner mitochondrial membrane and mutations in OPA1 are associated with autosomal dominant optic atrophy (DOA). OPA1 plays important roles in mitochondrial fusion, cristae remodeling and apoptosis. Our previous study showed that dOpa1 mutation caused elevated reactive oxygen species (ROS) production and resulted in damage and death of the cone and pigment cells in Drosophila eyes. Since ROS-induced oxidative damage to the cells is one of the primary causes of aging, in this study, we examined the effects of heterozygous dOpa1 mutation on the lifespan. We found that heterozygous dOpa1 mutation caused shortened lifespan, increased susceptibility to oxidative stress and elevated production of ROS in the whole Drosophila. Antioxidant treatment partially restored lifespan in the male dOpa1 mutants, but had no effects in the females. Heterozygous dOpa1 mutation caused an impairment of respiratory chain complex activities, especially complexes II and III, and reversible decreased aconitase activity. Heterozygous dOpa1 mutation is also associated with irregular and dysmorphic mitochondria in the muscle. Our results, for the first time, demonstrate the important role of OPA1 in aging and lifespan, which is most likely mediated through augmented ROS production.
Collapse
Affiliation(s)
- Sha Tang
- Division of Human Genetics, Department of Pediatrics, University of California Irvine, Irvine, California, United States of America
| | - Phung Khanh Le
- Division of Human Genetics, Department of Pediatrics, University of California Irvine, Irvine, California, United States of America
| | - Stephanie Tse
- Division of Human Genetics, Department of Pediatrics, University of California Irvine, Irvine, California, United States of America
| | - Douglas C. Wallace
- Center for Molecular and Mitochondrial Medicine and Genetics, University of California Irvine, Irvine, California, United States of America
- Department of Biological Chemistry, University of California Irvine, Irvine, California, United States of America
| | - Taosheng Huang
- Division of Human Genetics, Department of Pediatrics, University of California Irvine, Irvine, California, United States of America
- Center for Molecular and Mitochondrial Medicine and Genetics, University of California Irvine, Irvine, California, United States of America
- Department of Developmental and Cell Biology, University of California Irvine, Irvine, California, United States of America
- Department of Pathology, University of California Irvine, Irvine, California, United States of America
- * E-mail:
| |
Collapse
|
45
|
Knott AB, Bossy-Wetzel E. Impairing the mitochondrial fission and fusion balance: a new mechanism of neurodegeneration. Ann N Y Acad Sci 2009; 1147:283-92. [PMID: 19076450 DOI: 10.1196/annals.1427.030] [Citation(s) in RCA: 178] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Mitochondrial dysfunction is a common characteristic of all neurodegenerative diseases. However, the cause of this dysfunction remains a mystery. Here, we discuss the potential role of mitochondrial fission and fusion in the onset and progression of neurodegenerative diseases. Specifically, we propose that an imbalance in mitochondrial fission and fusion may underlie both familial and sporadic neurodegenerative disorders. There is substantial evidence that links disruption of the mitochondrial fission and fusion equilibrium, resulting in abnormally long or short mitochondria, to neurodegeneration. First, hereditary mutations in the mitochondrial fusion GTPases optic atrophy-1 and mitofusin-2 cause neuropathies in humans. In addition, recent findings report increased mitochondrial fission in Parkinson's disease (PD) models and induction of mitochondrial fission by two proteins, PTEN-induced kinase 1 and parkin, which are mutant in familial forms of PD. Furthermore, mutant huntingtin, the disease-causing protein in Huntington's disease, alters mitochondrial morphology and dynamics. Rotenone, a pesticide and inducer of PD symptoms, and amyloid-beta peptide, which is causally linked to Alzheimer's disease, initiate mitochondrial fission. Finally, mitochondrial fission is an early event in ischemic stroke and diabetic neuropathies. In sum, a growing body of research suggests that a better understanding of mitochondrial fission and fusion and the regulatory factors involved may lead to improved treatments and cures for neurodegenerative diseases.
Collapse
Affiliation(s)
- Andrew B Knott
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32816, USA
| | | |
Collapse
|
46
|
Amiott EA, Lott P, Soto J, Kang PB, McCaffery JM, DiMauro S, Abel ED, Flanigan KM, Lawson VH, Shaw JM. Mitochondrial fusion and function in Charcot-Marie-Tooth type 2A patient fibroblasts with mitofusin 2 mutations. Exp Neurol 2008; 211:115-27. [PMID: 18316077 PMCID: PMC2409111 DOI: 10.1016/j.expneurol.2008.01.010] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2007] [Revised: 01/06/2008] [Accepted: 01/11/2008] [Indexed: 01/10/2023]
Abstract
Charcot-Marie-Tooth Type 2A is a dominantly inherited peripheral neuropathy characterized by axonal degeneration of sensory and motor nerves. The disease is caused by mutations in the mitochondrial fusion gene MFN2. Mfn2 is an integral outer mitochondrial membrane protein composed of a large GTPase domain and two heptad repeat (HR) domains that face the cytoplasm. Mitochondrial membrane fusion and division are balanced processes that are necessary to maintain tubular mitochondrial morphology, respiratory function, and uniform distribution of the organelle throughout the cell. We have utilized primary fibroblasts from CMT2A patients to survey mitochondrial phenotypes associated with heterozygous MFN2 alleles expressed at physiological levels. Our results indicate that, in fibroblasts, mitofusin expression, mitochondrial morphology, ultrastructure, mtDNA content, and respiratory capacity are not affected by the presence of mutant Mfn2 protein. Consistent with a lack of mitochondrial dysfunction, we also show that mitochondrial fusion occurs efficiently in CMT2A patient-derived fibroblasts. Our observations are in agreement with the neuronal specificity of the disease and are consistent with a recent finding that mitochondrial fusion can be maintained in cells that express mutant Mfn2 protein due to complementation by a second mitofusin, Mfn1. We discuss our results and those of others in terms of a comprehensive model for the mechanism(s) by which mutations in MFN2 may lead to CMT2A disease.
Collapse
Affiliation(s)
- Elizabeth A Amiott
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112
| | - Paul Lott
- Departments of Neurology, Human Genetics, Pathology, and Pediatrics, University of Utah School of Medicine, Salt Lake City, UT 84112
| | - Jamie Soto
- Division of Endocrinology Metabolism and Diabetes and Program in Human Molecular Biology and Genetics, University of Utah, School of Medicine, Salt Lake City, UT 84112
| | - Peter B Kang
- Department of Neurology, Children’s Hospital Boston and Harvard Medical School, Boston, MA 02115
| | - J Michael McCaffery
- Integrated Imaging Center, Department of Biology, Johns Hopkins University, Baltimore, MD 21218
| | - Salvatore DiMauro
- Department of Neurology, Columbia University Medical Center, New York, NY 10032
| | - E Dale Abel
- Division of Endocrinology Metabolism and Diabetes and Program in Human Molecular Biology and Genetics, University of Utah, School of Medicine, Salt Lake City, UT 84112
| | - Kevin M Flanigan
- Departments of Neurology, Human Genetics, Pathology, and Pediatrics, University of Utah School of Medicine, Salt Lake City, UT 84112
| | - Victoria H Lawson
- Departments of Neurology, Human Genetics, Pathology, and Pediatrics, University of Utah School of Medicine, Salt Lake City, UT 84112
| | - Janet M Shaw
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112
| |
Collapse
|
47
|
Zanna C, Ghelli A, Porcelli AM, Karbowski M, Youle RJ, Schimpf S, Wissinger B, Pinti M, Cossarizza A, Vidoni S, Valentino ML, Rugolo M, Carelli V. OPA1 mutations associated with dominant optic atrophy impair oxidative phosphorylation and mitochondrial fusion. ACTA ACUST UNITED AC 2008; 131:352-67. [PMID: 18222991 DOI: 10.1093/brain/awm335] [Citation(s) in RCA: 244] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Dominant optic atrophy (DOA) is characterized by retinal ganglion cell degeneration leading to optic neuropathy. A subset of DOA is caused by mutations in the OPA1 gene, encoding for a dynamin-related GTPase required for mitochondrial fusion. The functional consequences of OPA1 mutations in DOA patients are still poorly understood. This study investigated the effect of five different OPA1 pathogenic mutations on the energetic efficiency and mitochondrial network dynamics of skin fibroblasts from patients. Although DOA fibroblasts maintained their ATP levels and grew in galactose medium, i.e. under forced oxidative metabolism, a significant impairment in mitochondrial ATP synthesis driven by complex I substrates was found. Furthermore, balloon-like structures in the mitochondrial reticulum were observed in galactose medium and mitochondrial fusion was completely inhibited in about 50% of DOA fibroblasts, but not in control cells. Respiratory complex assembly and the expression level of complex I subunits were similar in control and DOA fibroblasts. Co-immunoprecipitation experiments revealed that OPA1 directly interacts with subunits of complexes I, II and III, but not IV and with apoptosis inducing factor. The results disclose a novel link between OPA1, apoptosis inducing factor and the respiratory complexes that may shed some light on the pathogenic mechanism of DOA.
Collapse
Affiliation(s)
- Claudia Zanna
- Dipartimento di Biologia Evoluzionistica Sperimentale, Università di Bologna, Via Irnerio 42, 40126 Bologna, Italy.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
48
|
Abstract
In this report, we present three families in which we identified asymptomatic carriers of a homozygous absence of the SMN1 gene. In the first family, the bialleleic deletion was found in three of four siblings: two affected brothers (SMA type 3a and 3b) and a 25-years-old asymptomatic sister. All of them have four SMN2 copies. In the second family, four of six siblings are affected (three suffer from SMA2 and one from SMA3a), each with three SMN2 copies. The clinically asymptomatic 47-year-old father has the biallelic deletion and four SMN2 copies. In the third family, the biallelic SMN1 absence was found in a girl affected with SMA1 and in her healthy 53-years-old father who had five SMN2 copies. Our findings as well as those of other authors show that an increased number of SMN2 copies in healthy carriers of the biallelic SMN1 deletion is an important SMA phenotype modifier, but probably not the only one.
Collapse
|
49
|
The C. elegans Opa1 homologue EAT-3 is essential for resistance to free radicals. PLoS Genet 2008; 4:e1000022. [PMID: 18454199 PMCID: PMC2265488 DOI: 10.1371/journal.pgen.1000022] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2007] [Accepted: 01/07/2008] [Indexed: 11/19/2022] Open
Abstract
The C. elegans eat-3 gene encodes a mitochondrial dynamin family member homologous to Opa1 in humans and Mgm1 in yeast. We find that mutations in the C. elegans eat-3 locus cause mitochondria to fragment in agreement with the mutant phenotypes observed in yeast and mammalian cells. Electron microscopy shows that the matrices of fragmented mitochondria in eat-3 mutants are divided by inner membrane septae, suggestive of a specific defect in fusion of the mitochondrial inner membrane. In addition, we find that C. elegans eat-3 mutant animals are smaller, grow slower, and have smaller broodsizes than C. elegans mutants with defects in other mitochondrial fission and fusion proteins. Although mammalian Opa1 is antiapoptotic, mutations in the canonical C. elegans cell death genes ced-3 and ced-4 do not suppress the slow growth and small broodsize phenotypes of eat-3 mutants. Instead, the phenotypes of eat-3 mutants are consistent with defects in oxidative phosphorylation. Moreover, eat-3 mutants are hypersensitive to paraquat, which promotes damage by free radicals, and they are sensitive to loss of the mitochondrial superoxide dismutase sod-2. We conclude that free radicals contribute to the pathology of C. elegans eat-3 mutants.
Collapse
|
50
|
Abstract
PURPOSE To describe the Stratus optical coherence tomography (OCT) retinal nerve fiber layer (RNFL) thickness profile of dominant optic atrophy (DOA), to differentiate it from that of glaucoma. METHODS RNFL thickness was measured using Stratus OCT in 32 eyes of 16 DOA patients. RESULTS The temporal-most clock hour measurement was outside the 95% normal limit in 29 of the 32 DOA eyes (90.6%). The pattern of RNFL damage was bilaterally symmetrical in location and severity in all subjects. CONCLUSION Stratus OCT shows characteristic findings differentiating DOA from glaucoma.
Collapse
|