1
|
Bernardino Gomes TM, Vincent AE, Menger KE, Stewart JB, Nicholls TJ. Mechanisms and pathologies of human mitochondrial DNA replication and deletion formation. Biochem J 2024; 481:683-715. [PMID: 38804971 DOI: 10.1042/bcj20230262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 05/13/2024] [Accepted: 05/14/2024] [Indexed: 05/29/2024]
Abstract
Human mitochondria possess a multi-copy circular genome, mitochondrial DNA (mtDNA), that is essential for cellular energy metabolism. The number of copies of mtDNA per cell, and their integrity, are maintained by nuclear-encoded mtDNA replication and repair machineries. Aberrant mtDNA replication and mtDNA breakage are believed to cause deletions within mtDNA. The genomic location and breakpoint sequences of these deletions show similar patterns across various inherited and acquired diseases, and are also observed during normal ageing, suggesting a common mechanism of deletion formation. However, an ongoing debate over the mechanism by which mtDNA replicates has made it difficult to develop clear and testable models for how mtDNA rearrangements arise and propagate at a molecular and cellular level. These deletions may impair energy metabolism if present in a high proportion of the mtDNA copies within the cell, and can be seen in primary mitochondrial diseases, either in sporadic cases or caused by autosomal variants in nuclear-encoded mtDNA maintenance genes. These mitochondrial diseases have diverse genetic causes and multiple modes of inheritance, and show notoriously broad clinical heterogeneity with complex tissue specificities, which further makes establishing genotype-phenotype relationships challenging. In this review, we aim to cover our current understanding of how the human mitochondrial genome is replicated, the mechanisms by which mtDNA replication and repair can lead to mtDNA instability in the form of large-scale rearrangements, how rearranged mtDNAs subsequently accumulate within cells, and the pathological consequences when this occurs.
Collapse
Affiliation(s)
- Tiago M Bernardino Gomes
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- NHS England Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE2 4HH, U.K
| | - Amy E Vincent
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Katja E Menger
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - James B Stewart
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Thomas J Nicholls
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| |
Collapse
|
2
|
Tábara LC, Burr SP, Frison M, Chowdhury SR, Paupe V, Nie Y, Johnson M, Villar-Azpillaga J, Viegas F, Segawa M, Anand H, Petkevicius K, Chinnery PF, Prudent J. MTFP1 controls mitochondrial fusion to regulate inner membrane quality control and maintain mtDNA levels. Cell 2024:S0092-8674(24)00526-9. [PMID: 38851188 DOI: 10.1016/j.cell.2024.05.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 03/19/2024] [Accepted: 05/09/2024] [Indexed: 06/10/2024]
Abstract
Mitochondrial dynamics play a critical role in cell fate decisions and in controlling mtDNA levels and distribution. However, the molecular mechanisms linking mitochondrial membrane remodeling and quality control to mtDNA copy number (CN) regulation remain elusive. Here, we demonstrate that the inner mitochondrial membrane (IMM) protein mitochondrial fission process 1 (MTFP1) negatively regulates IMM fusion. Moreover, manipulation of mitochondrial fusion through the regulation of MTFP1 levels results in mtDNA CN modulation. Mechanistically, we found that MTFP1 inhibits mitochondrial fusion to isolate and exclude damaged IMM subdomains from the rest of the network. Subsequently, peripheral fission ensures their segregation into small MTFP1-enriched mitochondria (SMEM) that are targeted for degradation in an autophagic-dependent manner. Remarkably, MTFP1-dependent IMM quality control is essential for basal nucleoid recycling and therefore to maintain adequate mtDNA levels within the cell.
Collapse
Affiliation(s)
- Luis Carlos Tábara
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK.
| | - Stephen P Burr
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK; Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge CB2 0QQ, UK
| | - Michele Frison
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK; Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge CB2 0QQ, UK
| | - Suvagata R Chowdhury
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK
| | - Vincent Paupe
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK
| | - Yu Nie
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK; Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge CB2 0QQ, UK
| | - Mark Johnson
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK
| | - Jara Villar-Azpillaga
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK
| | - Filipa Viegas
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK
| | - Mayuko Segawa
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK
| | - Hanish Anand
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK
| | - Kasparas Petkevicius
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK
| | - Patrick F Chinnery
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK; Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, Cambridge CB2 0QQ, UK
| | - Julien Prudent
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK.
| |
Collapse
|
3
|
Spinazzola A, Perez-Rodriguez D, Ježek J, Holt IJ. Mitochondrial DNA competition: starving out the mutant genome. Trends Pharmacol Sci 2024; 45:225-242. [PMID: 38402076 DOI: 10.1016/j.tips.2024.01.011] [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: 09/24/2023] [Revised: 01/11/2024] [Accepted: 01/22/2024] [Indexed: 02/26/2024]
Abstract
High levels of pathogenic mitochondrial DNA (mtDNA) variants lead to severe genetic diseases, and the accumulation of such mutants may also contribute to common disorders. Thus, selecting against these mutants is a major goal in mitochondrial medicine. Although mutant mtDNA can drift randomly, mounting evidence indicates that active forces play a role in the selection for and against mtDNA variants. The underlying mechanisms are beginning to be clarified, and recent studies suggest that metabolic cues, including fuel availability, contribute to shaping mtDNA heteroplasmy. In the context of pathological mtDNAs, remodeling of nutrient metabolism supports mitochondria with deleterious mtDNAs and enables them to outcompete functional variants owing to a replicative advantage. The elevated nutrient requirement represents a mutant Achilles' heel because small molecules that restrict nutrient consumption or interfere with nutrient sensing can purge cells of deleterious mtDNAs and restore mitochondrial respiration. These advances herald the dawn of a new era of small-molecule therapies to counteract pathological mtDNAs.
Collapse
Affiliation(s)
- Antonella Spinazzola
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Royal Free Campus, London NW3 2PF, UK.
| | - Diego Perez-Rodriguez
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Royal Free Campus, London NW3 2PF, UK
| | - Jan Ježek
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Royal Free Campus, London NW3 2PF, UK
| | - Ian J Holt
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Royal Free Campus, London NW3 2PF, UK; Biodonostia Health Research Institute, 20014 San Sebastián, Spain; IKERBASQUE (Basque Foundation for Science), 48013 Bilbao, Spain; CIBERNED (Center for Networked Biomedical Research on Neurodegenerative Diseases, Ministry of Economy and Competitiveness, Institute Carlos III), 28031 Madrid, Spain; Universidad de País Vasco, Barrio Sarriena s/n, 48940 Leioa, Bilbao, Spain.
| |
Collapse
|
4
|
Richards CJ, Pulido JS. Random Allelic Expression in Inherited Retinal Disease Genes. Curr Issues Mol Biol 2023; 45:10018-10025. [PMID: 38132471 PMCID: PMC10742332 DOI: 10.3390/cimb45120625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 12/03/2023] [Accepted: 12/06/2023] [Indexed: 12/23/2023] Open
Abstract
Inherited retinal diseases (IRDs) are a significant contributor to visual loss in children and young adults, falling second only to diabetic retinopathy. Understanding the pathogenic mechanisms of IRDs remains paramount. Some autosomal genes exhibit random allelic expression (RAE), similar to X-chromosome inactivation. This study identifies RAE genes in IRDs. Genes in the Retinal Information Network were cross-referenced with the recent literature to identify expression profiles, RAE, or biallelic expression (BAE). Loss-of-function intolerance (LOFI) was determined by cross-referencing the existing literature. Molecular and biological pathways that are significantly enriched were evaluated using gene ontology. A total of 184 IRD-causing genes were evaluated. Of these, 31 (16.8%) genes exhibited RAE. LOFI was exhibited in 6/31 (19.4%) of the RAE genes and 18/153 (11.8%) of the BAE genes. Brain tissue exhibited BAE in 107/128 (83.6%) genes for both sexes. The molecular pathways significantly enriched among BAE genes were photoreceptor activity, tubulin binding, and nucleotide/ribonucleotide binding. The biologic pathways significantly enriched for RAE genes were equilibrioception, parallel actin filament bundle assembly, photoreceptor cell outer segment organization, and protein depalmitoylation. Allele-specific expression may be a mechanism underlying IRD phenotypic variability, with clonal populations of embryologic precursor cells exhibiting RAE. Brain tissue preferentially exhibited BAE, possibly due to selective pressures against RAE. Pathways critical for cellular and visual function were enriched in BAE, which may offer a survival benefit.
Collapse
|
5
|
Shammas MK, Nie Y, Gilsrud A, Huang X, Narendra DP, Chinnery PF. CHCHD10 mutations induce tissue-specific mitochondrial DNA deletions with a distinct signature. Hum Mol Genet 2023; 33:91-101. [PMID: 37815936 PMCID: PMC10729859 DOI: 10.1093/hmg/ddad161] [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: 06/19/2023] [Revised: 09/11/2023] [Accepted: 09/19/2023] [Indexed: 10/12/2023] Open
Abstract
Mutations affecting the mitochondrial intermembrane space protein CHCHD10 cause human disease, but it is not known why different amino acid substitutions cause markedly different clinical phenotypes, including amyotrophic lateral sclerosis-frontotemporal dementia, spinal muscular atrophy Jokela-type, isolated autosomal dominant mitochondrial myopathy and cardiomyopathy. CHCHD10 mutations have been associated with deletions of mitochondrial DNA (mtDNA deletions), raising the possibility that these explain the clinical variability. Here, we sequenced mtDNA obtained from hearts, skeletal muscle, livers and spinal cords of WT and Chchd10 G58R or S59L knockin mice to characterise the mtDNA deletion signatures of the two mutant lines. We found that the deletion levels were higher in G58R and S59L mice than in WT mice in some tissues depending on the Chchd10 genotype, and the deletion burden increased with age. Furthermore, we observed that the spinal cord was less prone to the development of mtDNA deletions than the other tissues examined. Finally, in addition to accelerating the rate of naturally occurring deletions, Chchd10 mutations also led to the accumulation of a novel set of deletions characterised by shorter direct repeats flanking the deletion breakpoints. Our results indicate that Chchd10 mutations in mice induce tissue-specific deletions which may also contribute to the clinical phenotype associated with these mutations in humans.
Collapse
Affiliation(s)
- Mario K Shammas
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0QQ, United Kingdom
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, United Kingdom
- Inherited Movement Disorders Unit, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 35 Convent Drive, Bethesda, MD 20892, United States
| | - Yu Nie
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0QQ, United Kingdom
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, United Kingdom
| | - Alexandra Gilsrud
- Inherited Movement Disorders Unit, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 35 Convent Drive, Bethesda, MD 20892, United States
| | - Xiaoping Huang
- Inherited Movement Disorders Unit, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 35 Convent Drive, Bethesda, MD 20892, United States
| | - Derek P Narendra
- Inherited Movement Disorders Unit, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, 35 Convent Drive, Bethesda, MD 20892, United States
| | - Patrick F Chinnery
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0QQ, United Kingdom
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, United Kingdom
| |
Collapse
|
6
|
Chacko JA, Phillips PH, Ramakrishnaiah RH, Schaefer GB, Uwaydat SH. Diagnosis of Charcot-Marie-Tooth Disease in a Patient With Decreased Vision From Optic Atrophy and No Other Neurological Symptoms. J Neuroophthalmol 2023; 43:e146-e148. [PMID: 35427283 DOI: 10.1097/wno.0000000000001520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Joseph A Chacko
- Jones Eye Institute (JAC, PHP, SHU), University of Arkansas for Medical Sciences (UAMS), Little Rock, Arkansas; Department of Ophthalmology (PHP), Arkansas Children's Hospital, Little Rock, Arkansas; and Departments of Radiology (RHR) and Genetics (GBS), UAMS & Arkansas Children's Hospital, Little Rock, Arkansas
| | | | | | | | | |
Collapse
|
7
|
Wang Y, Dai X, Li H, Jiang H, Zhou J, Zhang S, Guo J, Shen L, Yang H, Lin J, Yan H. The role of mitochondrial dynamics in disease. MedComm (Beijing) 2023; 4:e462. [PMID: 38156294 PMCID: PMC10753647 DOI: 10.1002/mco2.462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 11/14/2023] [Accepted: 12/03/2023] [Indexed: 12/30/2023] Open
Abstract
Mitochondria are multifaceted and dynamic organelles regulating various important cellular processes from signal transduction to determining cell fate. As dynamic properties of mitochondria, fusion and fission accompanied with mitophagy, undergo constant changes in number and morphology to sustain mitochondrial homeostasis in response to cell context changes. Thus, the dysregulation of mitochondrial dynamics and mitophagy is unsurprisingly related with various diseases, but the unclear underlying mechanism hinders their clinical application. In this review, we summarize the recent developments in the molecular mechanism of mitochondrial dynamics and mitophagy, particularly the different roles of key components in mitochondrial dynamics in different context. We also summarize the roles of mitochondrial dynamics and target treatment in diseases related to the cardiovascular system, nervous system, respiratory system, and tumor cell metabolism demanding high-energy. In these diseases, it is common that excessive mitochondrial fission is dominant and accompanied by impaired fusion and mitophagy. But there have been many conflicting findings about them recently, which are specifically highlighted in this view. We look forward that these findings will help broaden our understanding of the roles of the mitochondrial dynamics in diseases and will be beneficial to the discovery of novel selective therapeutic targets.
Collapse
Affiliation(s)
- Yujuan Wang
- Immunotherapy LaboratoryQinghai Tibet Plateau Research InstituteSouthwest Minzu UniversityChengduSichuanChina
| | - Xinyan Dai
- Immunotherapy LaboratoryQinghai Tibet Plateau Research InstituteSouthwest Minzu UniversityChengduSichuanChina
| | - Hui Li
- Immunotherapy LaboratoryCollege of PharmacologySouthwest Minzu UniversityChengduSichuanChina
| | - Huiling Jiang
- Immunotherapy LaboratoryCollege of PharmacologySouthwest Minzu UniversityChengduSichuanChina
| | - Junfu Zhou
- Immunotherapy LaboratoryCollege of PharmacologySouthwest Minzu UniversityChengduSichuanChina
| | - Shiying Zhang
- Immunotherapy LaboratoryQinghai Tibet Plateau Research InstituteSouthwest Minzu UniversityChengduSichuanChina
| | - Jiacheng Guo
- Immunotherapy LaboratoryQinghai Tibet Plateau Research InstituteSouthwest Minzu UniversityChengduSichuanChina
| | - Lidu Shen
- Immunotherapy LaboratoryCollege of PharmacologySouthwest Minzu UniversityChengduSichuanChina
| | - Huantao Yang
- Immunotherapy LaboratoryQinghai Tibet Plateau Research InstituteSouthwest Minzu UniversityChengduSichuanChina
| | - Jie Lin
- Immunotherapy LaboratoryCollege of PharmacologySouthwest Minzu UniversityChengduSichuanChina
| | - Hengxiu Yan
- Immunotherapy LaboratoryCollege of PharmacologySouthwest Minzu UniversityChengduSichuanChina
| |
Collapse
|
8
|
Serag M, Plutino M, Charles P, Azulay JP, Chaussenot A, Paquis-Flucklinger V, Ait-El-Mkadem Saadi S, Rouzier C. A Case Report of SYNE1 Deficiency-Mimicking Mitochondrial Disease and the Value of Pangenomic Investigations. Genes (Basel) 2023; 14:2154. [PMID: 38136976 PMCID: PMC10743207 DOI: 10.3390/genes14122154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 11/24/2023] [Accepted: 11/27/2023] [Indexed: 12/24/2023] Open
Abstract
Mitochondrial disorders are characterized by a huge clinical, biochemical, and genetic heterogeneity, which poses significant diagnostic challenges. Several studies report that more than 50% of patients with suspected mitochondrial disease could have a non-mitochondrial disorder. Thus, only the identification of the causative pathogenic variant can confirm the diagnosis. Herein, we describe the diagnostic journey of a family suspected of having a mitochondrial disorder who were referred to our Genetics Department. The proband presented with the association of cerebellar ataxia, COX-negative fibers on muscle histology, and mtDNA deletions. Whole exome sequencing (WES), supplemented by a high-resolution array, comparative genomic hybridization (array-CGH), allowed us to identify two pathogenic variants in the non-mitochondrial SYNE1 gene. The proband and her affected sister were found to be compound heterozygous for a known nonsense variant (c.13258C>T, p.(Arg4420Ter)), and a large intragenic deletion that was predicted to result in a loss of function. To our knowledge, this is the first report of a large intragenic deletion of SYNE1 in patients with cerebellar ataxia (ARCA1). This report highlights the interest in a pangenomic approach to identify the genetic basis in heterogeneous neuromuscular patients with the possible cause of mitochondrial disease. Moreover, even rare copy number variations should be considered in patients with a phenotype suggestive of SYNE1 deficiency.
Collapse
Affiliation(s)
- Mounir Serag
- Service de Génétique Médicale, Hôpital l’Archet 2, CHU de Nice, 151 Route Saint-Antoine de Ginestière, 06202 Nice, France; (M.S.); (M.P.); (A.C.); (V.P.-F.); (S.A.-E.-M.S.)
- CNRS UMR7284/ INSERM U1081, Faculté de Médecine, Université Côte d’Azur, 06107 Nice, France
| | - Morgane Plutino
- Service de Génétique Médicale, Hôpital l’Archet 2, CHU de Nice, 151 Route Saint-Antoine de Ginestière, 06202 Nice, France; (M.S.); (M.P.); (A.C.); (V.P.-F.); (S.A.-E.-M.S.)
- CNRS UMR7284/ INSERM U1081, Faculté de Médecine, Université Côte d’Azur, 06107 Nice, France
| | - Perrine Charles
- Service de Génétique, La Pitié-Salpêtrière, AP-HP, 75610 Paris, France;
| | | | - Annabelle Chaussenot
- Service de Génétique Médicale, Hôpital l’Archet 2, CHU de Nice, 151 Route Saint-Antoine de Ginestière, 06202 Nice, France; (M.S.); (M.P.); (A.C.); (V.P.-F.); (S.A.-E.-M.S.)
- CNRS UMR7284/ INSERM U1081, Faculté de Médecine, Université Côte d’Azur, 06107 Nice, France
| | - Véronique Paquis-Flucklinger
- Service de Génétique Médicale, Hôpital l’Archet 2, CHU de Nice, 151 Route Saint-Antoine de Ginestière, 06202 Nice, France; (M.S.); (M.P.); (A.C.); (V.P.-F.); (S.A.-E.-M.S.)
- CNRS UMR7284/ INSERM U1081, Faculté de Médecine, Université Côte d’Azur, 06107 Nice, France
| | - Samira Ait-El-Mkadem Saadi
- Service de Génétique Médicale, Hôpital l’Archet 2, CHU de Nice, 151 Route Saint-Antoine de Ginestière, 06202 Nice, France; (M.S.); (M.P.); (A.C.); (V.P.-F.); (S.A.-E.-M.S.)
- CNRS UMR7284/ INSERM U1081, Faculté de Médecine, Université Côte d’Azur, 06107 Nice, France
| | - Cécile Rouzier
- Service de Génétique Médicale, Hôpital l’Archet 2, CHU de Nice, 151 Route Saint-Antoine de Ginestière, 06202 Nice, France; (M.S.); (M.P.); (A.C.); (V.P.-F.); (S.A.-E.-M.S.)
- CNRS UMR7284/ INSERM U1081, Faculté de Médecine, Université Côte d’Azur, 06107 Nice, France
| |
Collapse
|
9
|
Gazit I, Hecht I, Weiner C, Kotlyar A, Almer Z, Bakshi E, Or L, Volkov H, Feldman B, Maharshak I, Michelson M, Goldenberg-Cohen N, Pras E. Variants in the WDR45 Gene Within the OPA-2 Locus Associate With Isolated X-Linked Optic Atrophy. Invest Ophthalmol Vis Sci 2023; 64:17. [PMID: 37819743 PMCID: PMC10573587 DOI: 10.1167/iovs.64.13.17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 09/14/2023] [Indexed: 10/13/2023] Open
Abstract
Purpose To describe clinical and molecular findings of two families with X-linked optic atrophy and present two new pathogenic variants in the WDR45 gene. Methods Case series and molecular analysis of two families of Jewish Ashkenazi descent with early onset bilateral optic atrophy. Whole-exome sequencing (WES) and bioinformatic analysis were performed, followed by Sanger sequencing and segregation analysis. Results In both families, male siblings (three in family 1, two in family 2) had early-onset isolated bilateral optic atrophy. The sibling's healthy mother (and in the second family also one healthy sister) had a mild presentation, suggesting a carrier state and an X-linked inheritance pattern. All participants were otherwise healthy, apart from mild learning disabilities and autism spectrum disorder in two siblings of the second family. Variants in known optic atrophy genes were excluded. Analysis revealed a point variant in the WDR45 gene-a missense variant in the first family, NM_001029896.2:c.107C>A; NP_001025067.1:p.Pro36His (variant ID: 1704205), and a splice site variant in the second family, NM_001029896.2:c.236-1G>T; NP_009006.2:p.Val80Leu (variant ID: 1704204), located on Xp11.23 (OPA2 locus). Both variants are novel and predicted as pathogenic. In both families, the variant was seen with full segregation with the disease, occurring in all affected male participants and in one allele of the carrier females, as well as none of the healthy participants. Conclusions Among two families with isolated X-linked optic atrophy, molecular analysis revealed novel variants in the WDR45 gene in full segregation with the disease. This gene resides within the OPA2 locus, previously described to associate with X-linked optic atrophy. Taken together, these findings suggest that certain pathogenic variants in the WDR45 gene are associated with isolated X-linked optic atrophy.
Collapse
Affiliation(s)
- Inbal Gazit
- Department of Ophthalmology, Shamir Medical Center, Zerifin, Israel
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Idan Hecht
- Department of Ophthalmology, Shamir Medical Center, Zerifin, Israel
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- The Matlow's Ophthalmo-genetics Laboratory, Shamir Medical Center, Zerifin, Israel
| | - Chen Weiner
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- The Matlow's Ophthalmo-genetics Laboratory, Shamir Medical Center, Zerifin, Israel
| | - Alina Kotlyar
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- The Matlow's Ophthalmo-genetics Laboratory, Shamir Medical Center, Zerifin, Israel
| | - Zina Almer
- Department of Ophthalmology, Shamir Medical Center, Zerifin, Israel
| | - Erez Bakshi
- Department of Ophthalmology, Shamir Medical Center, Zerifin, Israel
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Lior Or
- Department of Ophthalmology, Shamir Medical Center, Zerifin, Israel
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Hadas Volkov
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Barak Feldman
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Idit Maharshak
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Department of Ophthalmology, Edith Wolfson Medical Center, Holon, Israel
| | - Marina Michelson
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- Institute of Medical Genetics, Wolfson Medical Center, Holon, Israel
- The Genetic Institute of Maccabi Health Medicinal Organization, Tel Aviv, Israel
| | - Nitza Goldenberg-Cohen
- Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel, and the Department of Ophthalmology, Bnai Zion Medical Center, Haifa, Israel
| | - Eran Pras
- Department of Ophthalmology, Shamir Medical Center, Zerifin, Israel
- Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- The Matlow's Ophthalmo-genetics Laboratory, Shamir Medical Center, Zerifin, Israel
| |
Collapse
|
10
|
Rebelo AP, Tomaselli PJ, Medina J, Wang Y, Dohrn MF, Nyvltova E, Danzi MC, Garrett M, Smith SE, Pestronk A, Li C, Ruiz A, Jacobs E, Feely SME, França MC, Gomes MV, Santos DF, Kumar S, Lombard DB, Saporta M, Hekimi S, Barrientos A, Weihl C, Shy ME, Marques W, Zuchner S. Biallelic variants in COQ7 cause distal hereditary motor neuropathy with upper motor neuron signs. Brain 2023; 146:4191-4199. [PMID: 37170631 PMCID: PMC10545612 DOI: 10.1093/brain/awad158] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 04/12/2023] [Accepted: 04/23/2023] [Indexed: 05/13/2023] Open
Abstract
COQ7 encodes a hydroxylase responsible for the penultimate step of coenzyme Q10 (CoQ10) biosynthesis in mitochondria. CoQ10 is essential for multiple cellular functions, including mitochondrial oxidative phosphorylation, lipid metabolism, and reactive oxygen species homeostasis. Mutations in COQ7 have been previously associated with primary CoQ10 deficiency, a clinically heterogeneous multisystemic mitochondrial disorder. We identified COQ7 biallelic variants in nine families diagnosed with distal hereditary motor neuropathy with upper neuron involvement, expending the clinical phenotype associated with defects in this gene. A recurrent p.Met1? change was identified in five families from Brazil with evidence of a founder effect. Fibroblasts isolated from patients revealed a substantial depletion of COQ7 protein levels, indicating protein instability leading to loss of enzyme function. High-performance liquid chromatography assay showed that fibroblasts from patients had reduced levels of CoQ10, and abnormal accumulation of the biosynthetic precursor DMQ10. Accordingly, fibroblasts from patients displayed significantly decreased oxygen consumption rates in patients, suggesting mitochondrial respiration deficiency. Induced pluripotent stem cell-derived motor neurons from patient fibroblasts showed significantly increased levels of extracellular neurofilament light protein, indicating axonal degeneration. Our findings indicate a molecular pathway involving CoQ10 biosynthesis deficiency and mitochondrial dysfunction in patients with distal hereditary motor neuropathy. Further studies will be important to evaluate the potential benefits of CoQ10 supplementation in the clinical outcome of the disease.
Collapse
Affiliation(s)
- Adriana P Rebelo
- Dr. John T. Macdonald Foundation, Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami, Miller School of Medicine, Miami, FL 33136, USA
| | - Pedro J Tomaselli
- Department of Neurology, University of São Paulo, Ribeirão Preto, 14048-900, Brazil
| | - Jessica Medina
- Dr. John T. Macdonald Foundation, Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami, Miller School of Medicine, Miami, FL 33136, USA
| | - Ying Wang
- Department of Biology, McGill University, Montreal, QC, H3A 1A1, Canada
| | - Maike F Dohrn
- Dr. John T. Macdonald Foundation, Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami, Miller School of Medicine, Miami, FL 33136, USA
- Department of Neurology, Medical Faculty, RWTH Aachen University, Aachen 52074, Germany
| | - Eva Nyvltova
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Matt C Danzi
- Dr. John T. Macdonald Foundation, Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami, Miller School of Medicine, Miami, FL 33136, USA
| | - Mark Garrett
- Department of Neurology, Washington University, St. Louis, MO 63112, USA
| | - Sean E Smith
- Department of Neurology, Washington University, St. Louis, MO 63112, USA
| | - Alan Pestronk
- Department of Neurology, Washington University, St. Louis, MO 63112, USA
| | - Chengcheng Li
- Department of Neurology, Washington University, St. Louis, MO 63112, USA
| | - Ariel Ruiz
- Dr. John T. Macdonald Foundation, Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami, Miller School of Medicine, Miami, FL 33136, USA
| | - Elizabeth Jacobs
- Dr. John T. Macdonald Foundation, Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami, Miller School of Medicine, Miami, FL 33136, USA
| | - Shawna M E Feely
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Marcondes C França
- Department of Neurology, University of São Paulo, Ribeirão Preto, 14048-900, Brazil
| | - Marcus V Gomes
- Department of Neurology, University of São Paulo, Ribeirão Preto, 14048-900, Brazil
| | - Diogo F Santos
- Department of Neurology, Federal University of Uberlândia, Uberlândia, MG 38405-320, Brazil
| | - Surinder Kumar
- Department of Pathology & Laboratory Medicine, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - David B Lombard
- Department of Pathology & Laboratory Medicine, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Mario Saporta
- Dr. John T. Macdonald Foundation, Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami, Miller School of Medicine, Miami, FL 33136, USA
| | - Siegfried Hekimi
- Department of Biology, McGill University, Montreal, QC, H3A 1A1, Canada
| | - Antoni Barrientos
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Conrad Weihl
- Department of Neurology, Washington University, St. Louis, MO 63112, USA
| | - Michael E Shy
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Wilson Marques
- Department of Neurology, University of São Paulo, Ribeirão Preto, 14048-900, Brazil
| | - Stephan Zuchner
- Dr. John T. Macdonald Foundation, Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami, Miller School of Medicine, Miami, FL 33136, USA
| |
Collapse
|
11
|
Stavropoulos F, Georgiou E, Schiza N, Bell S, Baloh RH, Kleopa KA, Sargiannidou I. Mitofusin 1 overexpression rescues the abnormal mitochondrial dynamics caused by the Mitofusin 2 K357T mutation in vitro. J Peripher Nerv Syst 2023; 28:329-340. [PMID: 37220142 DOI: 10.1111/jns.12564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 05/12/2023] [Accepted: 05/19/2023] [Indexed: 05/25/2023]
Abstract
BACKGROUND AND AIMS Mitofusin 1 (MFN1) and MFN2 are outer mitochondrial membrane fusogenic proteins regulating mitochondrial network morphology. MFN2 mutations cause Charcot-Marie-Tooth type 2A (CMT2A), an axonal neuropathy characterized by mitochondrial fusion defects, which in the case of a GTPase domain mutant, were rescued following wild-type MFN1/2 (MFN1/2WT ) overexpression. In this study, we compared the therapeutic efficiency between MFN1WT and MFN2WT overexpression in correcting mitochondrial defects induced by the novel MFN2K357T mutation located in the highly conserved R3 region. METHODS Constructs expressing either MFN2K357T , MFN2WT , or MFN1WT under the ubiquitous chicken β-actin hybrid (CBh) promoter were generated. Flag or myc tag was used for their detection. Differentiated SH-SY5Y cells were single transfected with MFN1WT , MFN2WT , or MFN2K357T , as well as double transfected with MFN2K357T /MFN2WT or MFN2K357T /MFN1WT . RESULTS SH-SY5Y cells transfected with MFN2K357T exhibited severe perinuclear mitochondrial clustering with axon-like processes devoid of mitochondria. Single transfection with MFN1WT resulted in a more interconnected mitochondrial network than transfection with MFN2WT , accompanied by mitochondrial clusters. Double transfection of MFN2K357T with either MFN1WT or MFN2WT resolved the mutant-induced mitochondrial clusters and led to detectable mitochondria throughout the axon-like processes. MFN1WT showed higher efficacy than MFN2WT in rescuing these defects. INTERPRETATION These results further demonstrate the higher potential of MFN1WT over MFN2WT overexpression to rescue CMT2A-induced mitochondrial network abnormalities due to mutations outside the GTPase domain. This higher phenotypic rescue conferred by MFN1WT , possibly due to its higher mitochondrial fusogenic ability, may be applied to different CMT2A cases regardless of the MFN2 mutation type.
Collapse
Affiliation(s)
- Filippos Stavropoulos
- Department of Neuroscience, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Elena Georgiou
- Department of Neuroscience, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Natasa Schiza
- Department of Neuroscience, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Shaughn Bell
- Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Robert H Baloh
- Global Head of Neuroscience, Novartis Institutes for BioMedical Research, Cambridge, Massachusetts, USA
| | - Kleopas A Kleopa
- Department of Neuroscience, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
- Center for Neuromuscular Disorders and Center for Multiple Sclerosis and Related Disorders, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Irene Sargiannidou
- Department of Neuroscience, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| |
Collapse
|
12
|
Hines TJ, Bailey J, Liu H, Guntur AR, Seburn KL, Pratt SL, Funke JR, Tarantino LM, Burgess RW. A Novel ENU-Induced Mfn2 Mutation Causes Motor Deficits in Mice without Causing Peripheral Neuropathy. BIOLOGY 2023; 12:953. [PMID: 37508383 PMCID: PMC10376023 DOI: 10.3390/biology12070953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 06/22/2023] [Accepted: 06/26/2023] [Indexed: 07/30/2023]
Abstract
Mitochondrial fission and fusion are required for maintaining functional mitochondria. The mitofusins (MFN1 and MFN2) are known for their roles in mediating mitochondrial fusion. Recently, MFN2 has been implicated in other important cellular functions, such as mitophagy, mitochondrial motility, and coordinating endoplasmic reticulum-mitochondria communication. In humans, over 100 MFN2 mutations are associated with a form of inherited peripheral neuropathy, Charcot-Marie-Tooth disease type 2A (CMT2A). Here we describe an ENU-induced mutant mouse line with a recessive neuromuscular phenotype. Behavioral screening showed progressive weight loss and rapid deterioration of motor function beginning at 8 weeks. Mapping and sequencing revealed a missense mutation in exon 18 of Mfn2 (T1928C; Leu643Pro), within the transmembrane domain. Compared to wild-type and heterozygous littermates, Mfn2L643P/L643P mice exhibited diminished rotarod performance and decreases in activity in the open field test, muscular endurance, mean mitochondrial diameter, sensory tests, mitochondrial DNA content, and MFN2 protein levels. However, tests of peripheral nerve physiology and histology were largely normal. Mutant leg bones had reduced cortical bone thickness and bone area fraction. Together, our data indicate that Mfn2L643P causes a recessive motor phenotype with mild bone and mitochondrial defects in mice. Lack of apparent nerve pathology notwithstanding, this is the first reported mouse model with a mutation in the transmembrane domain of the protein, which may be valuable for researchers studying MFN2 biology.
Collapse
Affiliation(s)
| | - Janice Bailey
- Department of Genetics, The University of North Carolina, Chapel Hill, NC 27599, USA
| | - Hedi Liu
- Department of Genetics, The University of North Carolina, Chapel Hill, NC 27599, USA
| | - Anyonya R Guntur
- Center for Molecular Medicine, Maine Health Institute for Research, Scarborough, ME 04074, USA
| | | | - Samia L Pratt
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
- Neuroscience Program, Graduate School of Biomedical Sciences, Tufts University, Boston, MA 02111, USA
| | - Jonathan R Funke
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
- Neuroscience Program, Graduate School of Biomedical Sciences, Tufts University, Boston, MA 02111, USA
| | - Lisa M Tarantino
- Department of Genetics, The University of North Carolina, Chapel Hill, NC 27599, USA
| | - Robert W Burgess
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
- Neuroscience Program, Graduate School of Biomedical Sciences, Tufts University, Boston, MA 02111, USA
| |
Collapse
|
13
|
Dorn GW. Reversing Dysdynamism to Interrupt Mitochondrial Degeneration in Amyotrophic Lateral Sclerosis. Cells 2023; 12:1188. [PMID: 37190097 PMCID: PMC10136928 DOI: 10.3390/cells12081188] [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: 03/01/2023] [Revised: 04/13/2023] [Accepted: 04/14/2023] [Indexed: 05/17/2023] Open
Abstract
Amyotrophic lateral sclerosis is one of several chronic neurodegenerative conditions in which mitochondrial abnormalities are posited to contribute to disease progression. Therapeutic options targeting mitochondria include enhancing metabolism, suppressing reactive oxygen production and disrupting mitochondria-mediated programmed cell death pathways. Herein is reviewed mechanistic evidence supporting a meaningful pathophysiological role for the constellation of abnormal mitochondrial fusion, fission and transport, collectively designated mitochondrial dysdynamism, in ALS. Following this is a discussion on preclinical studies in ALS mice that seemingly validate the idea that normalizing mitochondrial dynamism can delay ALS by interrupting a vicious cycle of mitochondrial degeneration, leading to neuronal die-back and death. Finally, the relative benefits of suppressing mitochondrial fusion vs. enhancing mitochondrial fusion in ALS are speculated upon, and the paper concludes with the prediction that the two approaches could be additive or synergistic, although a side-by-side comparative trial may be challenging to perform.
Collapse
Affiliation(s)
- Gerald W Dorn
- Department of Internal Medicine (Pharmacogenomics), Washington University School of Medicine, St. Louis, MO 63110, USA
| |
Collapse
|
14
|
Zanfardino P, Longo G, Amati A, Morani F, Picardi E, Girolamo F, Pafundi M, Cox SN, Manzari C, Tullo A, Doccini S, Santorelli FM, Petruzzella V. Mitofusin 2 mutation drives cell proliferation in Charcot-Marie-Tooth 2A fibroblasts. Hum Mol Genet 2023; 32:333-350. [PMID: 35994048 DOI: 10.1093/hmg/ddac201] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 08/12/2022] [Accepted: 08/16/2022] [Indexed: 01/20/2023] Open
Abstract
Dominant mutations in ubiquitously expressed mitofusin 2 gene (MFN2) cause Charcot-Marie-Tooth type 2A (CMT2A; OMIM 609260), an inherited sensory-motor neuropathy that affects peripheral nerve axons. Mitofusin 2 protein has been found to take part in mitochondrial fusion, mitochondria-endoplasmic reticulum tethering, mitochondrial trafficking along axons, mitochondrial quality control and various types of cancer, in which MFN2 has been indicated as a tumor suppressor gene. Discordant data on the mitochondrial altered phenotypes in patient-derived fibroblasts harboring MFN2 mutations and in animal models have been reported. We addressed some of these issues by focusing on mitochondria behavior during autophagy and mitophagy in fibroblasts derived from a CMT2AMFN2 patient with an MFN2650G > T/C217F mutation in the GTPase domain. This study investigated mitochondrial dynamics, respiratory capacity and autophagy/mitophagy, to tackle the multifaceted MFN2 contribution to CMT2A pathogenesis. We found that MFN2 mutated fibroblasts showed impairment of mitochondrial morphology, bioenergetics capacity, and impairment of the early stages of autophagy, but not mitophagy. Unexpectedly, transcriptomic analysis of mutated fibroblasts highlighted marked differentially expressed pathways related to cell population proliferation and extracellular matrix organization. We consistently found the activation of mTORC2/AKT signaling and accelerated proliferation in the CMT2AMFN2 fibroblasts. In conclusion, our evidence indicates that MFN2 mutation can positively drive cell proliferation in CMT2AMFN2 fibroblasts.
Collapse
Affiliation(s)
- Paola Zanfardino
- Department of Medical Basic Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, 70124 Bari, Italy
| | - Giovanna Longo
- Department of Medical Basic Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, 70124 Bari, Italy
| | - Alessandro Amati
- Department of Medical Basic Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, 70124 Bari, Italy
| | - Federica Morani
- Department of Biology, University of Pisa, 56126 Pisa, Italy
| | - Ernesto Picardi
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, 70125 Bari, Italy.,Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, 70125 Bari, Italy
| | - Francesco Girolamo
- Department of Medical Basic Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, 70124 Bari, Italy
| | - Mariella Pafundi
- Department of Medical Basic Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, 70124 Bari, Italy
| | - Sharon N Cox
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, 70125 Bari, Italy
| | - Caterina Manzari
- Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, 70125 Bari, Italy
| | - Apollonia Tullo
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, National Research Council, 70125 Bari, Italy
| | - Stefano Doccini
- Molecular Medicine for Neurodegenerative and Neuromuscular Diseases Unit, IRCCS Fondazione Stella Maris, 56128 Pisa, Italy
| | - Filippo M Santorelli
- Molecular Medicine for Neurodegenerative and Neuromuscular Diseases Unit, IRCCS Fondazione Stella Maris, 56128 Pisa, Italy
| | - Vittoria Petruzzella
- Department of Medical Basic Sciences, Neurosciences and Sense Organs, University of Bari Aldo Moro, 70124 Bari, Italy
| |
Collapse
|
15
|
Evaluation of optical coherence tomography findings and visual evoked potentials in Charcot-Marie-Tooth disease. Int Ophthalmol 2023; 43:333-341. [PMID: 35953577 DOI: 10.1007/s10792-022-02452-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 07/31/2022] [Indexed: 02/07/2023]
Abstract
PURPOSE To evaluate the spectral-domain optical coherence tomography (SD-OCT) findings and pattern visual evoked potential (VEP) in Charcot-Marie-Tooth (CMT) disease. METHODS Seventeen patients with CMT disease and 17 control subjects were included in the study. The patients were divided into two groups according to conduction velocity and inheritance pattern as demyelinating type (CMT 1) and axonal type (CMT 2). The average retinal nerve fiber layer (RNFL) thickness, RNFL thicknesses of all quadrants, and thicknesses of the ganglion cell layer complex (GCC) were measured using SD-OCT. Pattern VEP recordings were evaluated in both groups. RESULTS The average and four quadrants of RNFL thicknesses, and superior and inferior GCC thicknesses were significantly thinner in the CMT patients compared with healthy individuals, but there were no statistically significant differences between the CMT groups. There was a significant positive correlation between age and all RNFL and GCC thicknesses in the CMT 2 group and between age and RNFL thickness of the temporal quadrant in the CMT 1 group. P100 latencies were significantly delayed in the CMT groups compared with controls, and there were no significant differences in P100 latencies between the CMT groups (p < 0.001). VEP amplitudes were in normal ranges in the CMT groups. CONCLUSION This study showed that RNFL and GCC thicknesses were significantly reduced and VEP latencies were prolonged in patients with CMT with normal clinical examinations. Our results suggest that optic nerves may be affected more frequently in patients with CMT that is detected in clinical examinations.
Collapse
|
16
|
Abstract
Mitochondrial optic neuropathies have a leading role in the field of mitochondrial medicine ever since 1988, when the first mutation in mitochondrial DNA was associated with Leber's hereditary optic neuropathy (LHON). Autosomal dominant optic atrophy (DOA) was subsequently associated in 2000 with mutations in the nuclear DNA affecting the OPA1 gene. LHON and DOA are both characterized by selective neurodegeneration of retinal ganglion cells (RGCs) triggered by mitochondrial dysfunction. This is centered on respiratory complex I impairment in LHON and defective mitochondrial dynamics in OPA1-related DOA, leading to distinct clinical phenotypes. LHON is a subacute, rapid, severe loss of central vision involving both eyes within weeks or months, with age of onset between 15 and 35 years old. DOA is a more slowly progressive optic neuropathy, usually apparent in early childhood. LHON is characterized by marked incomplete penetrance and a clear male predilection. The introduction of next-generation sequencing has greatly expanded the genetic causes for other rare forms of mitochondrial optic neuropathies, including recessive and X-linked, further emphasizing the exquisite sensitivity of RGCs to compromised mitochondrial function. All forms of mitochondrial optic neuropathies, including LHON and DOA, can manifest either as pure optic atrophy or as a more severe multisystemic syndrome. Mitochondrial optic neuropathies are currently at the forefront of a number of therapeutic programs, including gene therapy, with idebenone being the only approved drug for a mitochondrial disorder.
Collapse
Affiliation(s)
- Valerio Carelli
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy; IRCCS Istituto di Scienze Neurologiche di Bologna, Programma di Neurogenetica, Bologna, Italy.
| | - Chiara La Morgia
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy; IRCCS Istituto di Scienze Neurologiche di Bologna, Programma di Neurogenetica, Bologna, Italy
| | - Patrick Yu-Wai-Man
- John van Geest Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom; Cambridge Eye Unit, Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, United Kingdom; Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom; Institute of Ophthalmology, University College London, London, United Kingdom
| |
Collapse
|
17
|
Luan Y, Jin Y, Zhang P, Li H, Yang Y. Mitochondria-associated endoplasmic reticulum membranes and cardiac hypertrophy: Molecular mechanisms and therapeutic targets. Front Cardiovasc Med 2022; 9:1015722. [PMID: 36337896 PMCID: PMC9630933 DOI: 10.3389/fcvm.2022.1015722] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 09/29/2022] [Indexed: 09/13/2023] Open
Abstract
Cardiac hypertrophy has been shown to compensate for cardiac performance and improve ventricular wall tension as well as oxygen consumption. This compensatory response results in several heart diseases, which include ischemia disease, hypertension, heart failure, and valvular disease. Although the pathogenesis of cardiac hypertrophy remains complicated, previous data show that dysfunction of the mitochondria and endoplasmic reticulum (ER) mediates the progression of cardiac hypertrophy. The interaction between the mitochondria and ER is mediated by mitochondria-associated ER membranes (MAMs), which play an important role in the pathology of cardiac hypertrophy. The function of MAMs has mainly been associated with calcium transfer, lipid synthesis, autophagy, and reactive oxygen species (ROS). In this review, we discuss key MAMs-associated proteins and their functions in cardiovascular system and define their roles in the progression of cardiac hypertrophy. In addition, we demonstrate that MAMs is a potential therapeutic target in the treatment of cardiac hypertrophy.
Collapse
Affiliation(s)
- Yi Luan
- Clinical Systems Biology Research Laboratories, Translational Medicine Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Yage Jin
- Department of Cardiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Pengjie Zhang
- Department of Ultrasound, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Hongqiang Li
- Department of Thyroid Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Yang Yang
- Clinical Systems Biology Research Laboratories, Translational Medicine Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| |
Collapse
|
18
|
Babu K, Seamon K, Jewell A, Harrison A, Harper A, Al Saif H, Couser N. Hereditary motor and sensory neuropathy type VIA with optic nerve pallor in two sisters with pathologic myopia: a case series and review. Ophthalmic Genet 2022:1-6. [PMID: 36098092 DOI: 10.1080/13816810.2022.2116651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
PURPOSE Hereditary Motor Sensory Neuropathy Type VIA with Optic Atrophy (HMSN6A) is a rare variant subtype of mitofusin 2 (MFN2) associated Charcot-Marie-Tooth disease, with ophthalmic manifestations largely limited to optic atrophy. We report a case series of two sisters with HMSN6A corresponding to known variants in the MFN2 gene. The proband's mother, maternal aunt, and maternal grandfather were also reportedly affected with the condition, although not examined at our institution. The clinical presentations of the proband and her sister are reviewed in detail. In addition, a comprehensive review of ophthalmic findings from prior reported cases of HMSN6A is provided. OBSERVATIONS HMSN6A is a neurologic disorder characterized by a motor sensory axonal neuropathy and optic atrophy. A range of additional ophthalmic manifestations have been reported in the literature. We highlight the proband and her sister who demonstrate this phenotype but also manifested other ocular abnormalities from an early age. In addition to optic nerve pallor, both sisters had additional ophthalmic features of bilateral pathologic myopia, limited vision, nystagmus, and strabismus. CONCLUSIONS AND IMPORTANCE This case series and review describe the ophthalmologic findings of HMSN6A and provides incentive to further investigate the correlation between molecular findings and the phenotype.
Collapse
Affiliation(s)
- Kevin Babu
- Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Kimberly Seamon
- Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA.,University of Florida College of Medicine, Jacksonville, Florida, USA
| | - Ann Jewell
- Department of Human and Molecular Genetics, Division of Clinical Genetics, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Anna Harrison
- Department of Ophthalmology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Amy Harper
- Department of Neurology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Hind Al Saif
- Department of Human and Molecular Genetics, Division of Clinical Genetics, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Natario Couser
- Department of Human and Molecular Genetics, Division of Clinical Genetics, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA.,Department of Ophthalmology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA.,Department of Pediatrics, Virginia Commonwealth University School of Medicine, Children's Hospital of Richmond at VCU, Richmond, Virginia, USA
| |
Collapse
|
19
|
Sharma G, Zaman M, Sabouny R, Joel M, Martens K, Martino D, de Koning AJ, Pfeffer G, Shutt TE. Characterization of a novel variant in the HR1 domain of MFN2 in a patient with ataxia, optic atrophy and sensorineural hearing loss. F1000Res 2022; 10:606. [PMID: 38274408 PMCID: PMC10808857 DOI: 10.12688/f1000research.53230.2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/22/2022] [Indexed: 01/27/2024] Open
Abstract
Background: Pathogenic variants in MFN2 cause Charcot-Marie-Tooth disease (CMT) type 2A (CMT2A) and are the leading cause of the axonal subtypes of CMT. CMT2A is characterized by predominantly distal motor weakness and muscle atrophy, with highly variable severity and onset age. Notably, some MFN2 variants can also lead to other phenotypes such as optic atrophy, hearing loss and lipodystrophy. Despite the clear link between MFN2 and CMT2A, our mechanistic understanding of how dysfunction of the MFN2 protein causes human disease pathologies remains incomplete. This lack of understanding is due in part to the multiple cellular roles of MFN2. Though initially characterized for its role in mediating mitochondrial fusion, MFN2 also plays important roles in mediating interactions between mitochondria and other organelles, such as the endoplasmic reticulum and lipid droplets. Additionally, MFN2 is also important for mitochondrial transport, mitochondrial autophagy, and has even been implicated in lipid transfer. Though over 100 pathogenic MFN2 variants have been described to date, only a few have been characterized functionally, and even then, often only for one or two functions. Method: Several MFN2-mediated functions were characterized in fibroblast cells from a patient presenting with cerebellar ataxia, deafness, blindness, and diffuse cerebral and cerebellar atrophy, who harbours a novel homozygous MFN2 variant, D414V, which is found in a region of the HR1 domain of MFN2 where few pathogenic variants occur. Results: We found evidence for impairment of several MFN2-mediated functions. Consistent with reduced mitochondrial fusion, patient fibroblasts exhibited more fragmented mitochondrial networks and had reduced mtDNA copy number. Additionally, patient fibroblasts had reduced oxygen consumption, fewer mitochondrial-ER contacts, and altered lipid droplets that displayed an unusual perinuclear distribution. Conclusion: Overall, this work characterizes D414V as a novel variant in MFN2 and expands the phenotypic presentation of MFN2 variants to include cerebellar ataxia.
Collapse
Affiliation(s)
- Govinda Sharma
- Departments of Medical Genetics and Biochemistry & Molecular Biology, Cumming School of Medicine, Alberta Children’s Hospital Research Institute, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, T2N 4N1, Canada
| | - Mashiat Zaman
- Departments of Medical Genetics and Biochemistry & Molecular Biology, Cumming School of Medicine, Alberta Children’s Hospital Research Institute, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, T2N 4N1, Canada
| | - Rasha Sabouny
- Departments of Medical Genetics and Biochemistry & Molecular Biology, Cumming School of Medicine, Alberta Children’s Hospital Research Institute, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, T2N 4N1, Canada
| | - Matthew Joel
- Department of Biochemistry & Molecular Biology, Cumming School of Medicine, Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, Alberta, T2N 4N1, Canada
- Departments of Clinical Neurosciences and Medical Genetics, Cumming School of Medicine, University of Calgary, Hotchkiss Brain Institute, Alberta Child Health Research Institute, Calgary, Alberta, T2N 4N1, Canada
| | - Kristina Martens
- Departments of Clinical Neurosciences and Medical Genetics, Cumming School of Medicine, University of Calgary, Hotchkiss Brain Institute, Alberta Child Health Research Institute, Calgary, Alberta, T2N 4N1, Canada
| | - Davide Martino
- Department of Clinical Neurosciences, Cumming School of Medicine, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, T2N 4N1, Canada
| | - A.P. Jason de Koning
- Department of Biochemistry & Molecular Biology, Cumming School of Medicine, Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, Alberta, T2N 4N1, Canada
| | - Gerald Pfeffer
- Departments of Clinical Neurosciences and Medical Genetics, Cumming School of Medicine, University of Calgary, Hotchkiss Brain Institute, Alberta Child Health Research Institute, Calgary, Alberta, T2N 4N1, Canada
| | - Timothy E. Shutt
- Departments of Medical Genetics and Biochemistry & Molecular Biology, Cumming School of Medicine, Alberta Children’s Hospital Research Institute, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, T2N 4N1, Canada
| |
Collapse
|
20
|
Charif M, Chevrollier A, Gueguen N, Kane S, Bris C, Goudenège D, Desquiret-Dumas V, Meunier I, Mochel F, Jeanjean L, Varenne F, Procaccio V, Reynier P, Bonneau D, Amati-Bonneau P, Lenaers G. Next-Generation Sequencing Identifies Novel PMPCA Variants in Patients with Late-Onset Dominant Optic Atrophy. Genes (Basel) 2022; 13:1202. [PMID: 35885985 PMCID: PMC9320445 DOI: 10.3390/genes13071202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 04/11/2022] [Accepted: 07/01/2022] [Indexed: 02/01/2023] Open
Abstract
Dominant Optic Atrophy (DOA) is one of the most common inherited mitochondrial diseases, leading to blindness. It is caused by the chronic degeneration of the retinal ganglion cells (RGCs) and their axons forming the optic nerve. Until now, DOA has been mainly associated with genes encoding proteins involved in mitochondrial network dynamics. Using next-generation and exome sequencing, we identified for the first time heterozygous PMPCA variants having a causative role in the pathology of late-onset primary DOA in five patients. PMPCA encodes an α subunit of the mitochondrial peptidase (MPP), responsible for the cleavage and maturation of the mitochondrial precursor proteins imported from the cytoplasm into mitochondria. Recently, PMPCA has been identified as the gene responsible for Autosomal Recessive Cerebellar Ataxia type 2 (SCAR2) and another severe recessive mitochondrial disease. In this study, four PMPCA variants were identified, two are frameshifts (c.309delA and c.820delG) classified as pathogenic and two are missenses (c.1363G>A and c.1547G>A) classified with uncertain pathological significance. Functional assays on patients’ fibroblasts show a hyperconnection of the mitochondrial network and revealed that frameshift variants reduced α-MPP levels, while not significantly affecting the respiratory machinery. These results suggest that alterations in mitochondrial peptidase function can affect the fusion-fission balance, a key element in maintaining the physiology of retinal ganglion cells, and consequently lead to their progressive degeneration.
Collapse
Affiliation(s)
- Majida Charif
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Institut MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (M.C.); (A.C.); (N.G.); (S.K.); (C.B.); (D.G.); (V.D.-D.); (V.P.); (P.R.); (D.B.); (P.A.-B.)
- Genetics and Immuno-Cell Therapy Team, Mohammed First University, Oujda 60000, Morocco
| | - Arnaud Chevrollier
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Institut MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (M.C.); (A.C.); (N.G.); (S.K.); (C.B.); (D.G.); (V.D.-D.); (V.P.); (P.R.); (D.B.); (P.A.-B.)
| | - Naïg Gueguen
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Institut MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (M.C.); (A.C.); (N.G.); (S.K.); (C.B.); (D.G.); (V.D.-D.); (V.P.); (P.R.); (D.B.); (P.A.-B.)
- Departments of Biochemistry and Molecular Biology, University Hospital Angers, 49933 Angers, France
| | - Selma Kane
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Institut MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (M.C.); (A.C.); (N.G.); (S.K.); (C.B.); (D.G.); (V.D.-D.); (V.P.); (P.R.); (D.B.); (P.A.-B.)
| | - Céline Bris
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Institut MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (M.C.); (A.C.); (N.G.); (S.K.); (C.B.); (D.G.); (V.D.-D.); (V.P.); (P.R.); (D.B.); (P.A.-B.)
- Departments of Biochemistry and Molecular Biology, University Hospital Angers, 49933 Angers, France
| | - David Goudenège
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Institut MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (M.C.); (A.C.); (N.G.); (S.K.); (C.B.); (D.G.); (V.D.-D.); (V.P.); (P.R.); (D.B.); (P.A.-B.)
- Departments of Biochemistry and Molecular Biology, University Hospital Angers, 49933 Angers, France
| | - Valerie Desquiret-Dumas
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Institut MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (M.C.); (A.C.); (N.G.); (S.K.); (C.B.); (D.G.); (V.D.-D.); (V.P.); (P.R.); (D.B.); (P.A.-B.)
- Departments of Biochemistry and Molecular Biology, University Hospital Angers, 49933 Angers, France
| | - Isabelle Meunier
- National Reference Centre for Inherited Sensory Diseases, University Hospital of Montpellier, University of Montpellier, 34000 Montpellier, France;
- Institut des Neurosciences de Montpellier, INSERM U1051, Université de Montpellier, 34000 Montpellier, France
| | - Fanny Mochel
- Department of Genetics, AP-HP, Pitié-Salpêtrière University Hospital, 75013 Paris, France;
| | - Luc Jeanjean
- Department of Ophthalmology, Nîmes University Hospital, CEDEX 9, 30900 Nîmes, France;
| | - Fanny Varenne
- Department of Ophthalmology, Hôpital Pierre Paul Riquet CHU Purpan, 31300 Toulouse, France;
| | - Vincent Procaccio
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Institut MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (M.C.); (A.C.); (N.G.); (S.K.); (C.B.); (D.G.); (V.D.-D.); (V.P.); (P.R.); (D.B.); (P.A.-B.)
- Departments of Genetics, University Hospital Angers, 49933 Angers, France
| | - Pascal Reynier
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Institut MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (M.C.); (A.C.); (N.G.); (S.K.); (C.B.); (D.G.); (V.D.-D.); (V.P.); (P.R.); (D.B.); (P.A.-B.)
- Departments of Biochemistry and Molecular Biology, University Hospital Angers, 49933 Angers, France
| | - Dominique Bonneau
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Institut MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (M.C.); (A.C.); (N.G.); (S.K.); (C.B.); (D.G.); (V.D.-D.); (V.P.); (P.R.); (D.B.); (P.A.-B.)
- Departments of Genetics, University Hospital Angers, 49933 Angers, France
| | - Patrizia Amati-Bonneau
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Institut MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (M.C.); (A.C.); (N.G.); (S.K.); (C.B.); (D.G.); (V.D.-D.); (V.P.); (P.R.); (D.B.); (P.A.-B.)
- Departments of Biochemistry and Molecular Biology, University Hospital Angers, 49933 Angers, France
| | - Guy Lenaers
- MitoLab Team, UMR CNRS 6015-INSERM U1083, Institut MitoVasc, SFR ICAT, Université d’Angers, 49933 Angers, France; (M.C.); (A.C.); (N.G.); (S.K.); (C.B.); (D.G.); (V.D.-D.); (V.P.); (P.R.); (D.B.); (P.A.-B.)
- Service de Neurologie, University Hospital Angers, 49933 Angers, France
| |
Collapse
|
21
|
Almannai M, Salah A, El-Hattab AW. Mitochondrial Membranes and Mitochondrial Genome: Interactions and Clinical Syndromes. MEMBRANES 2022; 12:membranes12060625. [PMID: 35736332 PMCID: PMC9229594 DOI: 10.3390/membranes12060625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 06/06/2022] [Accepted: 06/14/2022] [Indexed: 11/16/2022]
Abstract
Mitochondria are surrounded by two membranes; the outer mitochondrial membrane and the inner mitochondrial membrane. They are unique organelles since they have their own DNA, the mitochondrial DNA (mtDNA), which is replicated continuously. Mitochondrial membranes have direct interaction with mtDNA and are therefore involved in organization of the mitochondrial genome. They also play essential roles in mitochondrial dynamics and the supply of nucleotides for mtDNA synthesis. In this review, we will discuss how the mitochondrial membranes interact with mtDNA and how this interaction is essential for mtDNA maintenance. We will review different mtDNA maintenance disorders that result from defects in this crucial interaction. Finally, we will review therapeutic approaches relevant to defects in mitochondrial membranes.
Collapse
Affiliation(s)
- Mohammed Almannai
- Genetics and Precision Medicine Department, King Abdullah Specialized Children Hospital, Riyadh P.O. Box 22490, Saudi Arabia
- Correspondence:
| | - Azza Salah
- Department of Pediatrics, University Hospital Sharjah, Sharjah P.O. Box 72772, United Arab Emirates;
| | - Ayman W. El-Hattab
- Department of Pediatrics, University Hospital Sharjah, Sharjah P.O. Box 72772, United Arab Emirates;
- Department of Clinical Sciences, College of Medicine, University of Sharjah, Sharjah P.O. Box 27272, United Arab Emirates;
- Genetics and Metabolic Department, KidsHeart Medical Center, Abu Dhabi P.O. Box 505193, United Arab Emirates
| |
Collapse
|
22
|
Roy A, Kandettu A, Ray S, Chakrabarty S. Mitochondrial DNA replication and repair defects: Clinical phenotypes and therapeutic interventions. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148554. [PMID: 35341749 DOI: 10.1016/j.bbabio.2022.148554] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 03/06/2022] [Accepted: 03/16/2022] [Indexed: 12/15/2022]
Abstract
Mitochondria is a unique cellular organelle involved in multiple cellular processes and is critical for maintaining cellular homeostasis. This semi-autonomous organelle contains its circular genome - mtDNA (mitochondrial DNA), that undergoes continuous cycles of replication and repair to maintain the mitochondrial genome integrity. The majority of the mitochondrial genes, including mitochondrial replisome and repair genes, are nuclear-encoded. Although the repair machinery of mitochondria is quite efficient, the mitochondrial genome is highly susceptible to oxidative damage and other types of exogenous and endogenous agent-induced DNA damage, due to the absence of protective histones and their proximity to the main ROS production sites. Mutations in replication and repair genes of mitochondria can result in mtDNA depletion and deletions subsequently leading to mitochondrial genome instability. The combined action of mutations and deletions can result in compromised mitochondrial genome maintenance and lead to various mitochondrial disorders. Here, we review the mechanism of mitochondrial DNA replication and repair process, key proteins involved, and their altered function in mitochondrial disorders. The focus of this review will be on the key genes of mitochondrial DNA replication and repair machinery and the clinical phenotypes associated with mutations in these genes.
Collapse
Affiliation(s)
- Abhipsa Roy
- Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India
| | - Amoolya Kandettu
- Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India
| | - Swagat Ray
- Department of Life Sciences, School of Life and Environmental Sciences, University of Lincoln, Lincoln LN6 7TS, United Kingdom
| | - Sanjiban Chakrabarty
- Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India.
| |
Collapse
|
23
|
232nd ENMC International Workshop: Recommendations for treatment of mitochondrial DNA maintenance disorders. 16 – 18 June 2017, Heemskerk, The Netherlands. Neuromuscul Disord 2022; 32:609-620. [DOI: 10.1016/j.nmd.2022.05.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 05/12/2022] [Indexed: 11/24/2022]
|
24
|
Scheffer DDL, Garcia AA, Lee L, Mochly-Rosen D, Ferreira JCB. Mitochondrial Fusion, Fission, and Mitophagy in Cardiac Diseases: Challenges and Therapeutic Opportunities. Antioxid Redox Signal 2022; 36:844-863. [PMID: 35044229 PMCID: PMC9125524 DOI: 10.1089/ars.2021.0145] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Significance: Mitochondria play a critical role in the physiology of the heart by controlling cardiac metabolism, function, and remodeling. Accumulation of fragmented and damaged mitochondria is a hallmark of cardiac diseases. Recent Advances: Disruption of quality control systems that maintain mitochondrial number, size, and shape through fission/fusion balance and mitophagy results in dysfunctional mitochondria, defective mitochondrial segregation, impaired cardiac bioenergetics, and excessive oxidative stress. Critical Issues: Pharmacological tools that improve the cardiac pool of healthy mitochondria through inhibition of excessive mitochondrial fission, boosting mitochondrial fusion, or increasing the clearance of damaged mitochondria have emerged as promising approaches to improve the prognosis of heart diseases. Future Directions: There is a reasonable amount of preclinical evidence supporting the effectiveness of molecules targeting mitochondrial fission and fusion to treat cardiac diseases. The current and future challenges are turning these lead molecules into treatments. Clinical studies focusing on acute (i.e., myocardial infarction) and chronic (i.e., heart failure) cardiac diseases are needed to validate the effectiveness of such strategies in improving mitochondrial morphology, metabolism, and cardiac function. Antioxid. Redox Signal. 36, 844-863.
Collapse
Affiliation(s)
- Débora da Luz Scheffer
- Department of Anatomy, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Adriana Ann Garcia
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford University, Stanford, California, USA
| | - Lucia Lee
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford University, Stanford, California, USA
| | - Daria Mochly-Rosen
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford University, Stanford, California, USA
| | - Julio Cesar Batista Ferreira
- Department of Anatomy, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil.,Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford University, Stanford, California, USA
| |
Collapse
|
25
|
Kabanovski A, Donaldson L, Margolin E. Neuro-ophthalmological manifestations of Wolfram syndrome: Case series and review of the literature. J Neurol Sci 2022; 437:120267. [DOI: 10.1016/j.jns.2022.120267] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 04/03/2022] [Accepted: 04/15/2022] [Indexed: 12/13/2022]
|
26
|
Manini A, Abati E, Comi GP, Corti S, Ronchi D. Mitochondrial DNA homeostasis impairment and dopaminergic dysfunction: A trembling balance. Ageing Res Rev 2022; 76:101578. [PMID: 35114397 DOI: 10.1016/j.arr.2022.101578] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 12/26/2021] [Accepted: 01/28/2022] [Indexed: 02/07/2023]
Abstract
Maintenance of mitochondrial DNA (mtDNA) homeostasis includes a variety of processes, such as mtDNA replication, repair, and nucleotides synthesis, aimed at preserving the structural and functional integrity of mtDNA molecules. Mutations in several nuclear genes (i.e., POLG, POLG2, TWNK, OPA1, DGUOK, MPV17, TYMP) impair mtDNA maintenance, leading to clinical syndromes characterized by mtDNA depletion and/or deletions in affected tissues. In the past decades, studies have demonstrated a progressive accumulation of multiple mtDNA deletions in dopaminergic neurons of the substantia nigra in elderly population and, to a greater extent, in Parkinson's disease patients. Moreover, parkinsonism has been frequently described as a prominent clinical feature in mtDNA instability syndromes. Among Parkinson's disease-related genes with a significant role in mitochondrial biology, PARK2 and LRRK2 specifically take part in mtDNA maintenance. Moreover, a variety of murine models (i.e., "Mutator", "MitoPark", "PD-mitoPstI", "Deletor", "Twinkle-dup" and "TwinkPark") provided in vivo evidence that mtDNA stability is required to preserve nigrostriatal integrity. Here, we review and discuss the clinical, genetic, and pathological background underlining the link between impaired mtDNA homeostasis and dopaminergic degeneration.
Collapse
|
27
|
Zaman M, Shutt TE. The Role of Impaired Mitochondrial Dynamics in MFN2-Mediated Pathology. Front Cell Dev Biol 2022; 10:858286. [PMID: 35399520 PMCID: PMC8989266 DOI: 10.3389/fcell.2022.858286] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 03/07/2022] [Indexed: 12/17/2022] Open
Abstract
The Mitofusin 2 protein (MFN2), encoded by the MFN2 gene, was first described for its role in mediating mitochondrial fusion. However, MFN2 is now recognized to play additional roles in mitochondrial autophagy (mitophagy), mitochondrial motility, lipid transfer, and as a tether to other organelles including the endoplasmic reticulum (ER) and lipid droplets. The tethering role of MFN2 is an important mediator of mitochondrial-ER contact sites (MERCs), which themselves have many important functions that regulate mitochondria, including calcium homeostasis and lipid metabolism. Exemplifying the importance of MFN2, pathogenic variants in MFN2 are established to cause the peripheral neuropathy Charcot-Marie-Tooth Disease Subtype 2A (CMT2A). However, the mechanistic basis for disease is not clear. Moreover, additional pathogenic phenotypes such as lipomatosis, distal myopathy, optic atrophy, and hearing loss, can also sometimes be present in patients with CMT2A. Given these variable patient phenotypes, and the many cellular roles played by MFN2, the mechanistic underpinnings of the cellular impairments by which MFN2 dysfunction leads to disease are likely to be complex. Here, we will review what is known about the various functions of MFN2 that are impaired by pathogenic variants causing CMT2A, with a specific emphasis on the ties between MFN2 variants and MERCs.
Collapse
Affiliation(s)
- Mashiat Zaman
- Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, Canada
- Alberta Children’s Hospital Research Institute (ACHRI), Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Timothy E. Shutt
- Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB, Canada
- Alberta Children’s Hospital Research Institute (ACHRI), Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
- Department of Medical Genetics, University of Calgary, Calgary, AB, Canada
- *Correspondence: Timothy E. Shutt,
| |
Collapse
|
28
|
Peng X, Hou R, Yang Y, Luo Z, Cao Y. Current Studies of Mitochondrial Quality Control in the Preeclampsia. Front Cardiovasc Med 2022; 9:836111. [PMID: 35295266 PMCID: PMC8920482 DOI: 10.3389/fcvm.2022.836111] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 02/02/2022] [Indexed: 01/22/2023] Open
Abstract
Mitochondria are cellular energy powerhouses that play important roles in regulating cellular processes. Mitochondrial quality control (mQC), including mitochondrial biogenesis, mitophagy, mitochondrial fusion and fission, maintains physiological demand and adapts to changed conditions. mQC has been widely investigated in neurodegeneration, cardiovascular disease and cancer because of the high demand for ATP in these diseases. Although placental implantation and fetal growth similarly require a large amount of energy, the investigation of mQC in placental-originated preeclampsia (PE) is limited. We elucidate mitochondrial morphology and function in different pregnancy stages, outline the role of mQC in cellular homeostasis and PE and summarize the current findings of mQC-related PE studies. This review also provides suggestions on the future investigation of mQC in PE, which will lead to the development of new prevention and therapy strategies for PE.
Collapse
Affiliation(s)
- Xiaoqing Peng
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of Anhui Medical University, Hefei, China
- National Health Commission Key Laboratory of Study on Abnormal Gametes and Reproductive Tract (Anhui Medical University), Hefei, China
- School of Pharmacy, Anhui Medical University, Hefei, China
- The Key Laboratory of Major Autoimmune Diseases, Anhui Medical University, Hefei, China
| | - Ruirui Hou
- School of Pharmacy, Anhui Medical University, Hefei, China
- The Key Laboratory of Major Autoimmune Diseases, Anhui Medical University, Hefei, China
| | - Yuanyuan Yang
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Zhigang Luo
- Department of Cardiovascular, The First Affiliated Hospital of Anhui Medical University, Hefei, China
- Zhigang Luo
| | - Yunxia Cao
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of Anhui Medical University, Hefei, China
- National Health Commission Key Laboratory of Study on Abnormal Gametes and Reproductive Tract (Anhui Medical University), Hefei, China
- *Correspondence: Yunxia Cao
| |
Collapse
|
29
|
Zeviani M, Carelli V. Mitochondrial Retinopathies. Int J Mol Sci 2021; 23:210. [PMID: 35008635 PMCID: PMC8745158 DOI: 10.3390/ijms23010210] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 12/14/2021] [Accepted: 12/18/2021] [Indexed: 12/13/2022] Open
Abstract
The retina is an exquisite target for defects of oxidative phosphorylation (OXPHOS) associated with mitochondrial impairment. Retinal involvement occurs in two ways, retinal dystrophy (retinitis pigmentosa) and subacute or chronic optic atrophy, which are the most common clinical entities. Both can present as isolated or virtually exclusive conditions, or as part of more complex, frequently multisystem syndromes. In most cases, mutations of mtDNA have been found in association with mitochondrial retinopathy. The main genetic abnormalities of mtDNA include mutations associated with neurogenic muscle weakness, ataxia and retinitis pigmentosa (NARP) sometimes with earlier onset and increased severity (maternally inherited Leigh syndrome, MILS), single large-scale deletions determining Kearns-Sayre syndrome (KSS, of which retinal dystrophy is a cardinal symptom), and mutations, particularly in mtDNA-encoded ND genes, associated with Leber hereditary optic neuropathy (LHON). However, mutations in nuclear genes can also cause mitochondrial retinopathy, including autosomal recessive phenocopies of LHON, and slowly progressive optic atrophy caused by dominant or, more rarely, recessive, mutations in the fusion/mitochondrial shaping protein OPA1, encoded by a nuclear gene on chromosome 3q29.
Collapse
Affiliation(s)
- Massimo Zeviani
- Department of Neurosciences, The Clinical School, University of Padova, 35128 Padova, Italy
- Veneto Institute of Molecular Medicine, Via Orus 2, 35128 Padova, Italy
| | - Valerio Carelli
- Department of Biomedical and Neuromotor Sciences, University of Bologna, 40139 Bologna, Italy
- Programma di Neurogenetica, IRCCS Istituto delle Scienze Neurologiche di Bologna, Via Altura 6, 40139 Bologna, Italy
| |
Collapse
|
30
|
Nan H, Hata T, Fukao T, Fukao T, Chen W, Kurita T, Natori T, Takiyama Y. MFN2-related Charcot-Marie-Tooth Disease with Atypical Ocular Manifestations. Intern Med 2021; 60:3969-3974. [PMID: 34121014 PMCID: PMC8758439 DOI: 10.2169/internalmedicine.7463-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We herein describe a Charcot-Marie-Tooth disease (CMT) family with a MFN2 mutation with atypical ocular manifestations. The proband, his mother, his third daughter, and his deceased maternal grandfather all had symptoms of CMT and a visual impairment (either cataracts or severe astigmatism). On whole-exome sequencing for the proband having CMT and congenital cataracts, we identified a c.314C>T (p.Thr105Met) mutation in MFN2, but no mutation in the causative genes associated with cataracts. This missense mutation in MFN2 co-segregated with CMT and the atypical ocular manifestations in this family. The findings of this study might help to expand the clinical phenotype of heterogeneous MFN2-related CMT.
Collapse
Affiliation(s)
- Haitian Nan
- Department of Neurology, University of Yamanashi, Japan
| | - Takanori Hata
- Department of Neurology, University of Yamanashi, Japan
| | - Toko Fukao
- Department of Neurology, University of Yamanashi, Japan
| | | | - Wanjing Chen
- Department of Ophthalmology, University of Yamanashi, Japan
| | | | | | | |
Collapse
|
31
|
Strachan EL, Mac White-Begg D, Crean J, Reynolds AL, Kennedy BN, O'Sullivan NC. The Role of Mitochondria in Optic Atrophy With Autosomal Inheritance. Front Neurosci 2021; 15:784987. [PMID: 34867178 PMCID: PMC8634724 DOI: 10.3389/fnins.2021.784987] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 10/22/2021] [Indexed: 11/13/2022] Open
Abstract
Optic atrophy (OA) with autosomal inheritance is a form of optic neuropathy characterized by the progressive and irreversible loss of vision. In some cases, this is accompanied by additional, typically neurological, extra-ocular symptoms. Underlying the loss of vision is the specific degeneration of the retinal ganglion cells (RGCs) which form the optic nerve. Whilst autosomal OA is genetically heterogenous, all currently identified causative genes appear to be associated with mitochondrial organization and function. However, it is unclear why RGCs are particularly vulnerable to mitochondrial aberration. Despite the relatively high prevalence of this disorder, there are currently no approved treatments. Combined with the lack of knowledge concerning the mechanisms through which aberrant mitochondrial function leads to RGC death, there remains a clear need for further research to identify the underlying mechanisms and develop treatments for this condition. This review summarizes the genes known to be causative of autosomal OA and the mitochondrial dysfunction caused by pathogenic mutations. Furthermore, we discuss the suitability of available in vivo models for autosomal OA with regards to both treatment development and furthering the understanding of autosomal OA pathology.
Collapse
Affiliation(s)
- Elin L Strachan
- UCD Conway Institute, University College Dublin, Dublin, Ireland.,UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
| | - Delphi Mac White-Begg
- UCD Conway Institute, University College Dublin, Dublin, Ireland.,UCD School of Veterinary Medicine, University College Dublin, Dublin, Ireland
| | - John Crean
- UCD Conway Institute, University College Dublin, Dublin, Ireland.,UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland.,UCD Diabetes Complications Research Centre, Conway Institute of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
| | - Alison L Reynolds
- UCD Conway Institute, University College Dublin, Dublin, Ireland.,UCD School of Veterinary Medicine, University College Dublin, Dublin, Ireland
| | - Breandán N Kennedy
- UCD Conway Institute, University College Dublin, Dublin, Ireland.,UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
| | - Niamh C O'Sullivan
- UCD Conway Institute, University College Dublin, Dublin, Ireland.,UCD School of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
| |
Collapse
|
32
|
Chiaratti MR. Uncovering the important role of mitochondrial dynamics in oogenesis: impact on fertility and metabolic disorder transmission. Biophys Rev 2021; 13:967-981. [PMID: 35059021 PMCID: PMC8724343 DOI: 10.1007/s12551-021-00891-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Accepted: 11/01/2021] [Indexed: 12/12/2022] Open
Abstract
Oocyte health is tightly tied to mitochondria given their role in energy production, metabolite supply, calcium (Ca2+) buffering, and cell death regulation, among others. In turn, mitochondrial function strongly relies on these organelle dynamics once cyclic events of fusion and fission (division) are required for mitochondrial turnover, positioning, content homogenization, metabolic flexibility, interaction with subcellular compartments, etc. Importantly, during oogenesis, mitochondria change their architecture from an "orthodox" elongated shape characterized by the presence of numerous transversely oriented cristae to a round-to-oval morphology containing arched and concentrically arranged cristae. This, along with evidence showing that mitochondrial function is kept quiescent during most part of oocyte development, suggests an important role of mitochondrial dynamics in oogenesis. To investigate this, recent works have downregulated/upregulated in oocytes the expression of key effectors of mitochondrial dynamics, including mitofusins 1 (MFN1) and 2 (MFN2) and the dynamin-related protein 1 (DRP1). As a result, both MFN1 and DRP1 were found to be essential to oogenesis and fertility, while MFN2 deletion led to offspring with increased weight gain and glucose intolerance. Curiously, neither MFN1/MFN2 deficiency nor DRP1 overexpression enhanced mitochondrial fragmentation, indicating that mitochondrial size is strictly regulated in oocytes. Therefore, the present work seeks to discuss the role of mitochondria in supporting oogenesis as well as recent findings connecting defective mitochondrial dynamics in oocytes with infertility and transmission of metabolic disorders.
Collapse
Affiliation(s)
- Marcos Roberto Chiaratti
- Departamento de Genética e Evolução, Centro de Ciências Biológicas e da Saúde, Universidade Federal de São Carlos, São Carlos, 13565-905 Brazil
| |
Collapse
|
33
|
Aberrant Mitochondrial Dynamics and Exacerbated Response to Neuroinflammation in a Novel Mouse Model of CMT2A. Int J Mol Sci 2021; 22:ijms222111569. [PMID: 34769001 PMCID: PMC8584238 DOI: 10.3390/ijms222111569] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 10/06/2021] [Accepted: 10/20/2021] [Indexed: 01/09/2023] Open
Abstract
Charcot-Marie-Tooth disease type 2A (CMT2A) is the most common hereditary axonal neuropathy caused by mutations in MFN2 encoding Mitofusin-2, a multifunctional protein located in the outer mitochondrial membrane. In order to study the effects of a novel MFN2K357T mutation associated with early onset, autosomal dominant severe CMT2A, we generated a knock-in mouse model. While Mfn2K357T/K357T mouse pups were postnatally lethal, Mfn2+/K357T heterozygous mice were asymptomatic and had no histopathological changes in their sciatic nerves up to 10 months of age. However, immunofluorescence analysis of Mfn2+/K357T mice revealed aberrant mitochondrial clustering in the sciatic nerves from 6 months of age, in optic nerves from 8 months, and in lumbar spinal cord white matter at 10 months, along with microglia activation. Ultrastructural analyses confirmed dysmorphic mitochondrial aggregates in sciatic and optic nerves. After exposure of 6-month-old mice to lipopolysaccharide, Mfn2+/K357T mice displayed a higher immune response, a more severe motor impairment, and increased CNS inflammation, microglia activation, and macrophage infiltrates. Overall, ubiquitous Mfn2K357T expression renders the CNS and peripheral nerves of Mfn2+/K357T mice more susceptible to mitochondrial clustering, and augments their response to inflammation, modeling some cellular mechanisms that may be relevant for the development of neuropathy in patients with CMT2A.
Collapse
|
34
|
Pellino G, Faggioli R, Galuppi A, Leon A, Fusco C, Tugnoli V, Suppiej A. Mitofusin 2: The missing link between mtDNA maintenance defects and neurotransmitter disorders. Mitochondrion 2021; 61:159-164. [PMID: 34600155 DOI: 10.1016/j.mito.2021.09.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 09/01/2021] [Accepted: 09/27/2021] [Indexed: 02/07/2023]
Abstract
Mitofusin (MFN) 2 belongs to the large family of mitochondrial transmembrane GTPases and has a role in dynamic mitochondrial remodeling process governed by fusion and fission. MFN2 pathogenic variants classically cause Charcot-Marie-Tooth disease type 2A (CMT2A), the most common axonal form of CMT, but patients with complex and unusual phenotypes involving the central and peripheral nervous system have been described, with mitochondrial dysfunction proposed as the underlying pathogenic mechanism. Here, we report the first description of a neurochemical pattern of secondary alterations in the metabolism of biogenic amines linked to the de novo presence of the hotspot MFN2 pathogenic variant p.Arg104Trp. The infant presented a very early onset choreic movement disorder associated with severe axial hypotonia and fluctuating dystonia of limbs. The relationship between mitochondrial DNA (mtDNA) maintenance defects and dopaminergic neurotransmitter disorders, governed by MFN2, is discussed.
Collapse
Affiliation(s)
- Giuditta Pellino
- Pediatric Unit, Azienda USL Ferrara - Sant'Anna University Hospital of Ferrara, Ferrara, Italy.
| | - Raffaella Faggioli
- Department of Medical Sciences, Section of Pediatrics, University of Ferrara, Ferrara, Italy
| | - Anna Galuppi
- Child Neurology Unit, Azienda USL Ferrara, Ferrara, Italy
| | - Alberta Leon
- Research & Innovation Srl (R&I Genetics), Padova, Italy
| | - Carlo Fusco
- Child Neurology and Psychiatric Unit-Presidio Ospedaliero Santa Maria Nuova - AUSL - IRCCS of Reggio Emilia, Reggio Emilia, Italy
| | - Valeria Tugnoli
- Department of Neuroscience and Rehabilitation, Division of Neurology, Sant'Anna University Hospital of Ferrara, Ferrara, Italy
| | - Agnese Suppiej
- Department of Medical Sciences, Section of Pediatrics, University of Ferrara, Ferrara, Italy
| |
Collapse
|
35
|
Majorel-Beraud C, Baudou E, Walther-Louvier U, Espil-Taris C, Beze-Beyrie P, Cintas P, Rivier F, Cances C. Clinical Phenotype in an Early-Onset French Pediatric Population: Charcot-Marie-Tooth's Disease Type 2A. Neuropediatrics 2021; 52:351-357. [PMID: 33578441 DOI: 10.1055/s-0041-1723759] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Charcot-Marie-Tooth's disease type 2A (MCT2A), induced by mutation of the mitofusin 2 (MFN2) gene represents the main cause of MCT2. The aim of this study is to provide details of the clinical and electromyographic phenotype of MCT2A in a pediatric population. We conducted a French multicenter retrospective study, including all children with a genetic diagnosis of MCT2A. Thirteen MCT2A children were included with a beginning of symptoms before the age of 10 years ("early-onset group"). We report two new mutations: c.1070 A → T (p.Lys357.Met) and c.280 C → G (p.Arg94Gly). The evolution of the disease is marked by a fast worsening for three patients with loss of motor autonomy, while the evolution is relatively stable for eight patients. The group of early-onset MCT2A seems more heterogeneous than previously described, with a nonconstant severe phenotype.
Collapse
Affiliation(s)
- C Majorel-Beraud
- Unit of Pediatric Neurology, French Greater South-West Reference Center for Neuromuscular Diseases, Hôpital des Enfants, Toulouse University Hospital Center, Toulouse, France
| | - E Baudou
- Unit of Pediatric Neurology, French Greater South-West Reference Center for Neuromuscular Diseases, Hôpital des Enfants, Toulouse University Hospital Center, Toulouse, France
| | - U Walther-Louvier
- Unit of Pediatric Neurology, French Greater South-West Reference Center for Neuromuscular Diseases, Hôpital Gui de Chauliac, Montpellier University Hospital Center, Montpellier, France
| | - C Espil-Taris
- Unit of Pediatric Neurology, French Greater South-West Reference Center for Neuromuscular Diseases, Hôpital des Enfants, University Hospital Center Pellegrin, Bordeaux, France
| | - P Beze-Beyrie
- Unit of Pediatrics, Centre Hospitalier de Pau, Pau, France
| | - P Cintas
- Department of Neurology, Pierre Paul Riquet Hospital, University Hospital Center Purpan, Toulouse, France
| | - F Rivier
- Unit of Pediatric Neurology, French Greater South-West Reference Center for Neuromuscular Diseases, Hôpital Gui de Chauliac, Montpellier University Hospital Center, Montpellier, France
| | - C Cances
- Unit of Pediatric Neurology, French Greater South-West Reference Center for Neuromuscular Diseases, Hôpital des Enfants, Toulouse University Hospital Center, Toulouse, France
| |
Collapse
|
36
|
Emery JM, Ortiz RM. Mitofusin 2: A link between mitochondrial function and substrate metabolism? Mitochondrion 2021; 61:125-137. [PMID: 34536562 DOI: 10.1016/j.mito.2021.09.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 08/22/2021] [Accepted: 09/13/2021] [Indexed: 01/18/2023]
Abstract
Mitochondria are dynamic, interactive organelles that connect cellular signaling and whole-cell homeostasis. This "mitochatting" allows the cell to receive information about the mitochondria's condition before accommodating energy demands. Mitofusin 2 (Mfn2), an outer mitochondrial membrane fusion protein specializes in mediating mitochondrial homeostasis. Early studies defined the biological significance of Mfn2, while latter studies highlighted its role in substrate metabolism. However, determining Mfn2 potential to contribute to energy homeostasis needs study. This review summarizes current literature on mitochondrial metabolic processes, dynamics, and evidence of interactions among Mfn2 and regulatory processes that may link Mfn2's role in maintaining mitochondrial function and substrate metabolism.
Collapse
Affiliation(s)
- Janna M Emery
- Department of Molecular and Cellular Biology, School of Natural Sciences, University of California, Merced, United States.
| | - Rudy M Ortiz
- Department of Molecular and Cellular Biology, School of Natural Sciences, University of California, Merced, United States
| |
Collapse
|
37
|
Lin CW, Huang CW, Luo AC, Chou YT, Huang YS, Chen PL, Chen TC. Genetic Spectrum and Characteristics of Hereditary Optic Neuropathy in Taiwan. Genes (Basel) 2021; 12:genes12091378. [PMID: 34573359 PMCID: PMC8467776 DOI: 10.3390/genes12091378] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 07/20/2021] [Accepted: 08/30/2021] [Indexed: 12/30/2022] Open
Abstract
Hereditary optic neuropathy (HON) is a group of genetically heterogeneous diseases that cause optic nerve atrophy and lead to substantial visual impairment. HON may present with optic nerve atrophy only or in association with various systemic abnormalities. Although a genetic survey is indispensable for diagnosing HON, conventional sequencing techniques could render its diagnosis challenging. In this study, we attempted to explore the genetic background of patients with HON in Taiwan through capture-based next-generation sequencing targeting 52 HON-related genes. In total, 57 patients from 48 families were recruited, with 6 patients diagnosed as having Leber hereditary optic neuropathy through initial screening for three common variants (m.3460G>A, m.11778G>A, m.14484T>C). Disease-causing genotypes were identified in 14 (33.3%) probands, and OPA1 variants were the most prevalent cause of autosomal HON. Exposure to medications such as ethambutol could trigger an attack of autosomal dominant optic atrophy. WFS1 variants were identified in three probands with variable clinical features in our cohort. Hearing impairment could occur in patients with OPA1 or WFS1 variants. This is the first comprehensive study investigating the genetic characteristics of HON in Taiwan, especially for autosomal HON. Our results could provide useful information for clinical diagnosis and genetic counseling in this field.
Collapse
MESH Headings
- Adolescent
- Adult
- Aged
- Child
- Child, Preschool
- DNA Mutational Analysis/statistics & numerical data
- Female
- GTP Phosphohydrolases/genetics
- Genetic Counseling
- Genetic Testing/statistics & numerical data
- Humans
- Male
- Membrane Proteins/genetics
- Middle Aged
- Mutation
- Optic Atrophy, Autosomal Dominant/diagnosis
- Optic Atrophy, Autosomal Dominant/epidemiology
- Optic Atrophy, Autosomal Dominant/genetics
- Optic Atrophy, Hereditary, Leber/diagnosis
- Optic Atrophy, Hereditary, Leber/epidemiology
- Optic Atrophy, Hereditary, Leber/genetics
- Taiwan/epidemiology
- Young Adult
Collapse
Affiliation(s)
- Chao-Wen Lin
- Department of Ophthalmology, National Taiwan University Hospital, Taipei 100, Taiwan; (C.-W.L.); (C.-W.H.); (Y.-S.H.)
| | - Ching-Wen Huang
- Department of Ophthalmology, National Taiwan University Hospital, Taipei 100, Taiwan; (C.-W.L.); (C.-W.H.); (Y.-S.H.)
| | - Allen Chilun Luo
- Department of Medical Genetics, National Taiwan University Hospital, Taipei 100, Taiwan; (A.C.L.); (Y.-T.C.)
| | - Yuh-Tsyr Chou
- Department of Medical Genetics, National Taiwan University Hospital, Taipei 100, Taiwan; (A.C.L.); (Y.-T.C.)
| | - Yu-Shu Huang
- Department of Ophthalmology, National Taiwan University Hospital, Taipei 100, Taiwan; (C.-W.L.); (C.-W.H.); (Y.-S.H.)
| | - Pei-Lung Chen
- Department of Medical Genetics, National Taiwan University Hospital, Taipei 100, Taiwan; (A.C.L.); (Y.-T.C.)
- Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei 100, Taiwan
- Graduate Institute of Medical Genomics and Proteomics, College of Medicine, National Taiwan University, Taipei 100, Taiwan
- Correspondence: (P.-L.C.); (T.-C.C.); Tel.: +886-2-23123456 (ext. 71942) (P.-L.C.); +886-2-23123456 (ext. 63783) (T.-C.C.); Fax: +886-2-23934420 (T.-C.C.)
| | - Ta-Ching Chen
- Department of Ophthalmology, National Taiwan University Hospital, Taipei 100, Taiwan; (C.-W.L.); (C.-W.H.); (Y.-S.H.)
- Correspondence: (P.-L.C.); (T.-C.C.); Tel.: +886-2-23123456 (ext. 71942) (P.-L.C.); +886-2-23123456 (ext. 63783) (T.-C.C.); Fax: +886-2-23934420 (T.-C.C.)
| |
Collapse
|
38
|
Sharma G, Sabouny R, Joel M, Martens K, Martino D, de Koning AJ, Pfeffer G, Shutt TE. Characterization of a novel variant in the HR1 domain of MFN2 in a patient with ataxia, optic atrophy and sensorineural hearing loss. F1000Res 2021. [DOI: 10.12688/f1000research.53230.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Background: Pathogenic variants in MFN2 cause Charcot-Marie-Tooth disease (CMT) type 2A (CMT2A) and are the leading cause of the axonal subtypes of CMT. CMT2A is characterized by predominantly distal motor weakness and muscle atrophy, with highly variable severity and onset age. Notably, some MFN2 variants can also lead to other phenotypes such as optic atrophy, hearing loss and lipodystrophy. Despite the clear link between MFN2 and CMT2A, our mechanistic understanding of how dysfunction of the MFN2 protein causes human disease pathologies remains incomplete. This lack of understanding is due in part to the multiple cellular roles of MFN2. Though initially characterized for its role in mediating mitochondrial fusion, MFN2 also plays important roles in mediating interactions between mitochondria and other organelles, such as the endoplasmic reticulum and lipid droplets. Additionally, MFN2 is also important for mitochondrial transport, mitochondrial autophagy, and has even been implicated in lipid transfer. Though over 100 pathogenic MFN2 variants have been described to date, only a few have been characterized functionally, and even then, often only for one or two functions. Method: Several MFN2-mediated functions were characterized in fibroblast cells from a patient presenting with cerebellar ataxia, deafness, blindness, and diffuse cerebral and cerebellar atrophy, who harbours a novel homozygous MFN2 variant, D414V, which is found in a region of the HR1 domain of MFN2 where few pathogenic variants occur. Results: We found evidence for impairment of several MFN2-mediated functions. Consistent with reduced mitochondrial fusion, patient fibroblasts exhibited more fragmented mitochondrial networks and had reduced mtDNA copy number. Additionally, patient fibroblasts had reduced oxygen consumption, fewer mitochondrial-ER contacts, and altered lipid droplets that displayed an unusual perinuclear distribution. Conclusion: Overall, this work characterizes D414V as a novel variant in MFN2 and expands the phenotypic presentation of MFN2 variants to include cerebellar ataxia.
Collapse
|
39
|
Structure and Function of Mitochondria-Associated Endoplasmic Reticulum Membranes (MAMs) and Their Role in Cardiovascular Diseases. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2021; 2021:4578809. [PMID: 34336092 PMCID: PMC8289621 DOI: 10.1155/2021/4578809] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 06/30/2021] [Indexed: 12/12/2022]
Abstract
Abnormal function of suborganelles such as mitochondria and endoplasmic reticulum often leads to abnormal function of cardiomyocytes or vascular endothelial cells and cardiovascular disease (CVD). Mitochondria-associated membrane (MAM) is involved in several important cellular functions. Increasing evidence shows that MAM is involved in the pathogenesis of CVD. MAM mediates multiple cellular processes, including calcium homeostasis regulation, lipid metabolism, unfolded protein response, ROS, mitochondrial dynamics, autophagy, apoptosis, and inflammation, which are key risk factors for CVD. In this review, we discuss the structure of MAM and MAM-associated proteins, their role in CVD progression, and the potential use of MAM as the therapeutic targets for CVD treatment.
Collapse
|
40
|
Lenaers G, Neutzner A, Le Dantec Y, Jüschke C, Xiao T, Decembrini S, Swirski S, Kieninger S, Agca C, Kim US, Reynier P, Yu-Wai-Man P, Neidhardt J, Wissinger B. Dominant optic atrophy: Culprit mitochondria in the optic nerve. Prog Retin Eye Res 2021; 83:100935. [PMID: 33340656 DOI: 10.1016/j.preteyeres.2020.100935] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 12/05/2020] [Accepted: 12/09/2020] [Indexed: 12/14/2022]
Abstract
Dominant optic atrophy (DOA) is an inherited mitochondrial disease leading to specific degeneration of retinal ganglion cells (RGCs), thus compromising transmission of visual information from the retina to the brain. Usually, DOA starts during childhood and evolves to poor vision or legal blindness, affecting the central vision, whilst sparing the peripheral visual field. In 20% of cases, DOA presents as syndromic disorder, with secondary symptoms affecting neuronal and muscular functions. Twenty years ago, we demonstrated that heterozygous mutations in OPA1 are the most frequent molecular cause of DOA. Since then, variants in additional genes, whose functions in many instances converge with those of OPA1, have been identified by next generation sequencing. OPA1 encodes a dynamin-related GTPase imported into mitochondria and located to the inner membrane and intermembrane space. The many OPA1 isoforms, resulting from alternative splicing of three exons, form complex homopolymers that structure mitochondrial cristae, and contribute to fusion of the outer membrane, thus shaping the whole mitochondrial network. Moreover, OPA1 is required for oxidative phosphorylation, maintenance of mitochondrial genome, calcium homeostasis and regulation of apoptosis, thus making OPA1 the Swiss army-knife of mitochondria. Understanding DOA pathophysiology requires the understanding of RGC peculiarities with respect to OPA1 functions. Besides the tremendous energy requirements of RGCs to relay visual information from the eye to the brain, these neurons present unique features related to their differential environments in the retina, and to the anatomical transition occurring at the lamina cribrosa, which parallel major adaptations of mitochondrial physiology and shape, in the pre- and post-laminar segments of the optic nerve. Three DOA mouse models, with different Opa1 mutations, have been generated to study intrinsic mechanisms responsible for RGC degeneration, and these have further revealed secondary symptoms related to mitochondrial dysfunctions, mirroring the more severe syndromic phenotypes seen in a subgroup of patients. Metabolomics analyses of cells, mouse organs and patient plasma mutated for OPA1 revealed new unexpected pathophysiological mechanisms related to mitochondrial dysfunction, and biomarkers correlated quantitatively to the severity of the disease. Here, we review and synthesize these data, and propose different approaches for embracing possible therapies to fulfil the unmet clinical needs of this disease, and provide hope to affected DOA patients.
Collapse
Affiliation(s)
- Guy Lenaers
- MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, Angers University and Hospital, Angers, France.
| | - Albert Neutzner
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland; Department of Ophthalmology University Hospital Basel, University of Basel, Basel, Switzerland.
| | - Yannick Le Dantec
- MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, Angers University and Hospital, Angers, France
| | - Christoph Jüschke
- Human Genetics, Faculty VI - School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
| | - Ting Xiao
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Center for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Sarah Decembrini
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland; Department of Ophthalmology University Hospital Basel, University of Basel, Basel, Switzerland
| | - Sebastian Swirski
- Human Genetics, Faculty VI - School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
| | - Sinja Kieninger
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Center for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Cavit Agca
- Molecular Biology, Genetics and Bioengineering Program, Sabanci University, Istanbul, Turkey; Nanotechnology Research and Application Center (SUNUM), Sabanci University, Istanbul, Turkey
| | - Ungsoo S Kim
- Kim's Eye Hospital, Seoul, South Korea; Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK; Cambridge Eye Unit, Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, UK; Moorfields Eye Hospital, London, UK
| | - Pascal Reynier
- MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, Angers University and Hospital, Angers, France; Department of Biochemistry, University Hospital of Angers, Angers, France
| | - Patrick Yu-Wai-Man
- Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK; Cambridge Eye Unit, Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, UK; Moorfields Eye Hospital, London, UK; UCL Institute of Ophthalmology, University College London, London, UK
| | - John Neidhardt
- Human Genetics, Faculty VI - School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany; Research Center Neurosensory Science, University Oldenburg, Oldenburg, Germany.
| | - Bernd Wissinger
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Center for Ophthalmology, University of Tübingen, Tübingen, Germany.
| |
Collapse
|
41
|
Ramón J, Vila-Julià F, Molina-Granada D, Molina-Berenguer M, Melià MJ, García-Arumí E, Torres-Torronteras J, Cámara Y, Martí R. Therapy Prospects for Mitochondrial DNA Maintenance Disorders. Int J Mol Sci 2021; 22:6447. [PMID: 34208592 PMCID: PMC8234938 DOI: 10.3390/ijms22126447] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Revised: 06/10/2021] [Accepted: 06/11/2021] [Indexed: 02/07/2023] Open
Abstract
Mitochondrial DNA depletion and multiple deletions syndromes (MDDS) constitute a group of mitochondrial diseases defined by dysfunctional mitochondrial DNA (mtDNA) replication and maintenance. As is the case for many other mitochondrial diseases, the options for the treatment of these disorders are rather limited today. Some aggressive treatments such as liver transplantation or allogeneic stem cell transplantation are among the few available options for patients with some forms of MDDS. However, in recent years, significant advances in our knowledge of the biochemical pathomechanisms accounting for dysfunctional mtDNA replication have been achieved, which has opened new prospects for the treatment of these often fatal diseases. Current strategies under investigation to treat MDDS range from small molecule substrate enhancement approaches to more complex treatments, such as lentiviral or adenoassociated vector-mediated gene therapy. Some of these experimental therapies have already reached the clinical phase with very promising results, however, they are hampered by the fact that these are all rare disorders and so the patient recruitment potential for clinical trials is very limited.
Collapse
Affiliation(s)
- Javier Ramón
- Research Group on Neuromuscular and Mitochondrial Diseases, Vall d’Hebron Research Institute, Universitat Autònoma de Barcelona, 08035 Barcelona, Spain; (J.R.); (F.V.-J.); (D.M.-G.); (M.M.-B.); (M.J.M.); (E.G.-A.); (J.T.-T.); (Y.C.)
- Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Ferran Vila-Julià
- Research Group on Neuromuscular and Mitochondrial Diseases, Vall d’Hebron Research Institute, Universitat Autònoma de Barcelona, 08035 Barcelona, Spain; (J.R.); (F.V.-J.); (D.M.-G.); (M.M.-B.); (M.J.M.); (E.G.-A.); (J.T.-T.); (Y.C.)
- Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - David Molina-Granada
- Research Group on Neuromuscular and Mitochondrial Diseases, Vall d’Hebron Research Institute, Universitat Autònoma de Barcelona, 08035 Barcelona, Spain; (J.R.); (F.V.-J.); (D.M.-G.); (M.M.-B.); (M.J.M.); (E.G.-A.); (J.T.-T.); (Y.C.)
- Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Miguel Molina-Berenguer
- Research Group on Neuromuscular and Mitochondrial Diseases, Vall d’Hebron Research Institute, Universitat Autònoma de Barcelona, 08035 Barcelona, Spain; (J.R.); (F.V.-J.); (D.M.-G.); (M.M.-B.); (M.J.M.); (E.G.-A.); (J.T.-T.); (Y.C.)
- Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Maria Jesús Melià
- Research Group on Neuromuscular and Mitochondrial Diseases, Vall d’Hebron Research Institute, Universitat Autònoma de Barcelona, 08035 Barcelona, Spain; (J.R.); (F.V.-J.); (D.M.-G.); (M.M.-B.); (M.J.M.); (E.G.-A.); (J.T.-T.); (Y.C.)
- Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Elena García-Arumí
- Research Group on Neuromuscular and Mitochondrial Diseases, Vall d’Hebron Research Institute, Universitat Autònoma de Barcelona, 08035 Barcelona, Spain; (J.R.); (F.V.-J.); (D.M.-G.); (M.M.-B.); (M.J.M.); (E.G.-A.); (J.T.-T.); (Y.C.)
- Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Javier Torres-Torronteras
- Research Group on Neuromuscular and Mitochondrial Diseases, Vall d’Hebron Research Institute, Universitat Autònoma de Barcelona, 08035 Barcelona, Spain; (J.R.); (F.V.-J.); (D.M.-G.); (M.M.-B.); (M.J.M.); (E.G.-A.); (J.T.-T.); (Y.C.)
- Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Yolanda Cámara
- Research Group on Neuromuscular and Mitochondrial Diseases, Vall d’Hebron Research Institute, Universitat Autònoma de Barcelona, 08035 Barcelona, Spain; (J.R.); (F.V.-J.); (D.M.-G.); (M.M.-B.); (M.J.M.); (E.G.-A.); (J.T.-T.); (Y.C.)
- Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Ramon Martí
- Research Group on Neuromuscular and Mitochondrial Diseases, Vall d’Hebron Research Institute, Universitat Autònoma de Barcelona, 08035 Barcelona, Spain; (J.R.); (F.V.-J.); (D.M.-G.); (M.M.-B.); (M.J.M.); (E.G.-A.); (J.T.-T.); (Y.C.)
- Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
| |
Collapse
|
42
|
Abstract
BACKGROUND Charcot-Marie-Tooth disease Type 2A (CMT2A) presents with optic atrophy in a subset of patients, but the prevalence and severity of optic nerve involvement in relation to other CMT subtypes has not been explored. METHODS Patients with genetically confirmed CMT2A (n = 5), CMT1A (n = 9) and CMTX1 (n = 10) underwent high- and low-contrast acuity testing using Sloan letter charts, and circumpapillary retinal nerve fiber layer (RNFL) and macular total retinal, RNFL, and ganglion cell layer/inner plexiform layer thickness was measured using spectral domain optical coherence tomography (OCT). We used age- and gender-adjusted linear regression to compare contrast acuity and retinal thickness between CMT groups. RESULTS One of 5 patients with CMT2A had optic nerve atrophy (binocular high-contrast acuity equivalent 20/160, mean circumpapillary RNFL 47.5 μm). The other patients with CMT2A had normal high- and low-contrast acuity and retinal thickness, and there were no significant differences between patients with CMT2A, CMT1A, and CMTX1. CONCLUSIONS Optic atrophy occurs in some patients with CMT2A, but in others, there is no discernible optic nerve involvement. This suggests that optic neuropathy is specific to certain MFN2 mutations in CMT2A and that low-contrast acuity or OCT is of limited value as a disease-wide biomarker.
Collapse
Affiliation(s)
- Ali G Hamedani
- Department of Neurology (AGH, JAW, RAA, SSS), Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Translational Center of Excellence for Neuroepidemiology and Neurology Outcomes Research (AGH), University of Pennsylvania, Philadelphia, Pennsylvania; Center for Clinical Epidemiology and Biostatistics (AGH), University of Pennsylvania, Philadelphia, Pennsylvania; Department of Ophthalmology (RAA), Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; and Division of Ophthalmology (RAA), Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | | | | | | |
Collapse
|
43
|
Wang X, Wen Y, Zhang J, Swanson G, Guo S, Cao C, Krawetz SA, Zhang Z, Yuan S. MFN2 interacts with nuage-associated proteins and is essential for male germ cell development by controlling mRNA fate during spermatogenesis. Development 2021; 148:dev.196295. [PMID: 33674260 DOI: 10.1242/dev.196295] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 02/26/2021] [Indexed: 01/06/2023]
Abstract
Mitochondria play a crucial role in spermatogenesis and are regulated by several mitochondrial fusion proteins. However, their functional importance associated with their structure formation and mRNA fate regulation during spermatogenesis remains unclear. Here, we show that mitofusin 2 (MFN2), a mitochondrial fusion protein, interacts with nuage-associated proteins (including MIWI, DDX4, TDRKH and GASZ) in mice. Conditional mutation of Mfn2 in postnatal germ cells results in male sterility due to germ cell developmental defects. Moreover, MFN2 interacts with MFN1, another mitochondrial fusion protein with a high-sequence similarity to MFN2, in testes to facilitate spermatogenesis. Simultaneous mutation of Mfn1 and Mfn2 in testes causes very severe infertile phenotypes. Importantly, we show that MFN2 is enriched in polysome fractions of testes and interacts with MSY2, a germ cell-specific DNA/RNA-binding protein, to control gamete-specific mRNA (such as Spata19) translational activity during spermatogenesis. Collectively, our findings demonstrate that MFN2 interacts with nuage-associated proteins and MSY2 to regulate male germ cell development by controlling several gamete-specific mRNA fates.
Collapse
Affiliation(s)
- Xiaoli Wang
- Institute of Reproductive Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Yujiao Wen
- Institute of Reproductive Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Jin Zhang
- Institute of Reproductive Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Grace Swanson
- Department of Obstetrics & Gynecology, Wayne State University, Detroit, MI 48201, USA
| | - Shuangshuang Guo
- Institute of Reproductive Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Congcong Cao
- Institute of Reproductive Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Stephen A Krawetz
- Department of Obstetrics & Gynecology, Wayne State University, Detroit, MI 48201, USA
| | - Zhibing Zhang
- Department of Obstetrics & Gynecology, Wayne State University, Detroit, MI 48201, USA.,Department of Physiology, Wayne State University, Detroit, MI 48201, USA
| | - Shuiqiao Yuan
- Institute of Reproductive Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.,Shenzhen Huazhong University of Science and Technology Research Institute, Shenzhen, Guangdong 518057, China
| |
Collapse
|
44
|
McTernan PM, Katz PS, Porretta C, Welsh DA, Siggins RW. A Novel FACS-Based Workflow for Simultaneous Assessment of RedOx Status, Cellular Phenotype, and Mitochondrial Genome Stability. BIOCHEM 2021; 1:1-18. [PMID: 35937039 PMCID: PMC9355044 DOI: 10.3390/biochem1010001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Intracellular reduction-oxidation (RedOx) status mediates a myriad of critical biological processes. Importantly, RedOx status regulates the differentiation of hematopoietic stem and progenitor cells (HSPCs), mesenchymal stromal cells (MSCs) and maturation of CD8+ T Lymphocytes. In most cells, mitochondria are the greatest contributors of intracellular reactive oxygen species (ROS). Excess ROS leads to mitochondrial DNA (mtDNA) damage and protein depletion. We have developed a fluorescence-activated cell sorting (FACS)-based protocol to simultaneously analyze RedOx status and mtDNA integrity. This simultaneous analysis includes measurements of ROS (reduced glutathione (GSH)), ATP5H (nuclear encoded protein), MTCO1 (mitochondrial DNA encoded protein), and cell surface markers to allow discrimination of different cell populations. Using the ratio of MTCO1 to ATP5H median fluorescence intensity (MFI), we can gain an understanding of mtDNA genomic stability, since MTCO1 levels are decreased when mtDNA becomes significantly damaged. Furthermore, this workflow can be optimized for sorting cells, using any of the above parameters, allowing for downstream quantification of mtDNA genome copies/nucleus by quantitative PCR (qPCR). This unique methodology can be used to enhance analyses of the impacts of pharmacological interventions, as well as physiological and pathophysiological processes on RedOx status along with mitochondrial dynamics in most cell types.
Collapse
Affiliation(s)
- Patrick M. McTernan
- Comprehensive Alcohol Research Center, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
- Department of Physiology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - Paige S. Katz
- Department of Physiology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - Constance Porretta
- Comprehensive Alcohol Research Center, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
- Department of Physiology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - David A. Welsh
- Comprehensive Alcohol Research Center, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
- Department of Medicine, Section of Pulmonary and Critical Care Medicine, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - Robert W. Siggins
- Comprehensive Alcohol Research Center, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
- Department of Physiology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
- Correspondence: ; Tel.: +1-504-568-2045
| |
Collapse
|
45
|
Sharma G, Pfeffer G, Shutt TE. Genetic Neuropathy Due to Impairments in Mitochondrial Dynamics. BIOLOGY 2021; 10:268. [PMID: 33810506 PMCID: PMC8066130 DOI: 10.3390/biology10040268] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 03/19/2021] [Accepted: 03/21/2021] [Indexed: 12/12/2022]
Abstract
Mitochondria are dynamic organelles capable of fusing, dividing, and moving about the cell. These properties are especially important in neurons, which in addition to high energy demand, have unique morphological properties with long axons. Notably, mitochondrial dysfunction causes a variety of neurological disorders including peripheral neuropathy, which is linked to impaired mitochondrial dynamics. Nonetheless, exactly why peripheral neurons are especially sensitive to impaired mitochondrial dynamics remains somewhat enigmatic. Although the prevailing view is that longer peripheral nerves are more sensitive to the loss of mitochondrial motility, this explanation is insufficient. Here, we review pathogenic variants in proteins mediating mitochondrial fusion, fission and transport that cause peripheral neuropathy. In addition to highlighting other dynamic processes that are impacted in peripheral neuropathies, we focus on impaired mitochondrial quality control as a potential unifying theme for why mitochondrial dysfunction and impairments in mitochondrial dynamics in particular cause peripheral neuropathy.
Collapse
Affiliation(s)
- Govinda Sharma
- Departments of Medical Genetics and Biochemistry & Molecular Biology, Cumming School of Medicine, Alberta Children’s Hospital Research Institute, Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada;
| | - Gerald Pfeffer
- Departments of Clinical Neurosciences and Medical Genetics, Cumming School of Medicine, Hotchkiss Brain Institute, Alberta Child Health Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada;
| | - Timothy E. Shutt
- Departments of Medical Genetics and Biochemistry & Molecular Biology, Cumming School of Medicine, Alberta Children’s Hospital Research Institute, Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada;
| |
Collapse
|
46
|
Charif M, Bris C, Goudenège D, Desquiret-Dumas V, Colin E, Ziegler A, Procaccio V, Reynier P, Bonneau D, Lenaers G, Amati-Bonneau P. Use of Next-Generation Sequencing for the Molecular Diagnosis of 1,102 Patients With a Autosomal Optic Neuropathy. Front Neurol 2021; 12:602979. [PMID: 33841295 PMCID: PMC8027346 DOI: 10.3389/fneur.2021.602979] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 02/01/2021] [Indexed: 11/13/2022] Open
Abstract
Advances in next-generation sequencing (NGS) facilitate the diagnosis of genetic disorders. To evaluate its use for the molecular diagnosis of inherited optic neuropathy (ION), a blinding disease caused by the degeneration of retinal ganglion cells, we performed genetic analysis using targeted NGS of 22 already known and candidate genes in a cohort of 1,102 affected individuals. The panel design, library preparation, and sequencing reactions were performed using the Ion AmpliSeq technology. Pathogenic variants were detected in 16 genes in 245 patients (22%), including 186 (17%) and 59 (5%) dominant and recessive cases, respectively. Results confirmed that OPA1 variants are responsible for the majority of dominant IONs, whereas ACO2 and WFS1 variants are also frequently involved in both dominant and recessive forms of ION. All pathogenic variants were found in genes encoding proteins involved in the mitochondrial function, highlighting the importance of mitochondria in the survival of retinal ganglion cells.
Collapse
Affiliation(s)
- Majida Charif
- University Angers, MitoLab team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Angers, France.,Genetics and Immuno-Cell Therapy Team, Mohammed First University, Oujda, Morocco
| | - Céline Bris
- University Angers, MitoLab team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Angers, France.,Departments of Biochemistry and Genetics, University Hospital Angers, Angers, France
| | - David Goudenège
- University Angers, MitoLab team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Angers, France.,Departments of Biochemistry and Genetics, University Hospital Angers, Angers, France
| | - Valérie Desquiret-Dumas
- University Angers, MitoLab team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Angers, France.,Departments of Biochemistry and Genetics, University Hospital Angers, Angers, France
| | - Estelle Colin
- University Angers, MitoLab team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Angers, France.,Departments of Biochemistry and Genetics, University Hospital Angers, Angers, France
| | - Alban Ziegler
- University Angers, MitoLab team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Angers, France.,Departments of Biochemistry and Genetics, University Hospital Angers, Angers, France
| | - Vincent Procaccio
- University Angers, MitoLab team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Angers, France.,Departments of Biochemistry and Genetics, University Hospital Angers, Angers, France
| | - Pascal Reynier
- University Angers, MitoLab team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Angers, France.,Departments of Biochemistry and Genetics, University Hospital Angers, Angers, France
| | - Dominique Bonneau
- University Angers, MitoLab team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Angers, France.,Departments of Biochemistry and Genetics, University Hospital Angers, Angers, France
| | - Guy Lenaers
- University Angers, MitoLab team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Angers, France
| | - Patrizia Amati-Bonneau
- University Angers, MitoLab team, UMR CNRS 6015-INSERM U1083, Unité MitoVasc, SFR ICAT, Angers, France.,Departments of Biochemistry and Genetics, University Hospital Angers, Angers, France
| |
Collapse
|
47
|
Maresca A, Carelli V. Molecular Mechanisms behind Inherited Neurodegeneration of the Optic Nerve. Biomolecules 2021; 11:496. [PMID: 33806088 PMCID: PMC8064499 DOI: 10.3390/biom11040496] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 03/22/2021] [Accepted: 03/23/2021] [Indexed: 01/01/2023] Open
Abstract
Inherited neurodegeneration of the optic nerve is a paradigm in neurology, as many forms of isolated or syndromic optic atrophy are encountered in clinical practice. The retinal ganglion cells originate the axons that form the optic nerve. They are particularly vulnerable to mitochondrial dysfunction, as they present a peculiar cellular architecture, with axons that are not myelinated for a long intra-retinal segment, thus, very energy dependent. The genetic landscape of causative mutations and genes greatly enlarged in the last decade, pointing to common pathways. These mostly imply mitochondrial dysfunction, which leads to a similar outcome in terms of neurodegeneration. We here critically review these pathways, which include (1) complex I-related oxidative phosphorylation (OXPHOS) dysfunction, (2) mitochondrial dynamics, and (3) endoplasmic reticulum-mitochondrial inter-organellar crosstalk. These major pathogenic mechanisms are in turn interconnected and represent the target for therapeutic strategies. Thus, their deep understanding is the basis to set and test new effective therapies, an urgent unmet need for these patients. New tools are now available to capture all interlinked mechanistic intricacies for the pathogenesis of optic nerve neurodegeneration, casting hope for innovative therapies to be rapidly transferred into the clinic and effectively cure inherited optic neuropathies.
Collapse
Affiliation(s)
- Alessandra Maresca
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, 40139 Bologna, Italy;
| | - Valerio Carelli
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, 40139 Bologna, Italy;
- Department of Biomedical and Neuromotor Sciences, University of Bologna, 40139 Bologna, Italy
| |
Collapse
|
48
|
Jacinto S, Guerreiro P, de Oliveira RM, Cunha-Oliveira T, Santos MJ, Grazina M, Rego AC, Outeiro TF. MPV17 Mutations Are Associated With a Quiescent Energetic Metabolic Profile. Front Cell Neurosci 2021; 15:641264. [PMID: 33815063 PMCID: PMC8011494 DOI: 10.3389/fncel.2021.641264] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Accepted: 02/08/2021] [Indexed: 02/03/2023] Open
Abstract
Mutations in the MPV17 gene are associated with hepatocerebral form of mitochondrial depletion syndrome. The mechanisms through which MPV17 mutations cause respiratory chain dysfunction and mtDNA depletion is still unclear. The MPV17 gene encodes an inner membrane mitochondrial protein that was recently described to function as a non-selective channel. Although its exact function is unknown, it is thought to be important in the maintenance of mitochondrial membrane potential (ΔΨm). To obtain more information about the role of MPV17 in human disease, we investigated the effect of MPV17 knockdown and of selected known MPV17 mutations associated with MPV17 disease in vitro. We used different approaches in order to evaluate the cellular consequences of MPV17 deficiency. We found that lower levels of MPV17 were associated with impaired mitochondrial respiration and with a quiescent energetic metabolic profile. All the mutations studied destabilized the protein, resulting in reduced protein levels. We also demonstrated that different mutations caused different cellular abnormalities, including increased ROS production, decreased oxygen consumption, loss of ΔΨm, and mislocalization of MPV17 protein. Our study provides novel insight into the molecular effects of MPV17 mutations and opens novel possibilities for testing therapeutic strategies for a devastating group of disorders.
Collapse
Affiliation(s)
- Sandra Jacinto
- Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal.,Serviço de Neurologia Pediátrica, Hospital Dona Estefânia, Centro Hospitalar Universitário Lisboa Central-EPE, Lisboa, Portugal
| | - Patrícia Guerreiro
- Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany.,Switch Laboratory, Center for Brain and Disease Research, Vlaams Instituut voor Biotechnologie (VIB), Leuven, Belgium.,Switch Laboratory, Department of Cellular and Molecular Medicine, Katholiek Universiteit (KU), Leuven, Belgium
| | - Rita Machado de Oliveira
- CEDOC - Chronic Diseases Research Center, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisboa, Portugal
| | | | - Maria João Santos
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Faculty of Medicine, University of Coimbra, Coimbra, Portugal.,CIBB - Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Portugal
| | - Manuela Grazina
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Faculty of Medicine, University of Coimbra, Coimbra, Portugal.,CIBB - Center for Innovative Biomedicine and Biotechnology, University of Coimbra, Portugal
| | - Ana Cristina Rego
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - Tiago F Outeiro
- Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany.,Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom.,Max Planck Institute for Experimental Medicine, Göttingen, Germany
| |
Collapse
|
49
|
Charif M, Wong YC, Kim S, Guichet A, Vignal C, Zanlonghi X, Bensaid P, Procaccio V, Bonneau D, Amati-Bonneau P, Reynier P, Krainc D, Lenaers G. Dominant mutations in MIEF1 affect mitochondrial dynamics and cause a singular late onset optic neuropathy. Mol Neurodegener 2021; 16:12. [PMID: 33632269 PMCID: PMC7905578 DOI: 10.1186/s13024-021-00431-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 02/08/2021] [Indexed: 02/01/2023] Open
Abstract
Inherited optic neuropathies are the most common mitochondrial diseases, leading to neurodegeneration involving the irreversible loss of retinal ganglion cells, optic nerve degeneration and central visual loss. Importantly, properly regulated mitochondrial dynamics are critical for maintaining cellular homeostasis, and are further regulated by MIEF1 (mitochondrial elongation factor 1) which encodes for MID51 (mitochondrial dynamics protein 51), an outer mitochondrial membrane protein that acts as an adaptor protein to regulate mitochondrial fission. However, dominant mutations in MIEF1 have not been previously linked to any human disease. Using targeted sequencing of genes involved in mitochondrial dynamics, we report the first heterozygous variants in MIEF1 linked to disease, which cause an unusual form of late-onset progressive optic neuropathy characterized by the initial loss of peripheral visual fields. Pathogenic MIEF1 variants linked to optic neuropathy do not disrupt MID51's localization to the outer mitochondrial membrane or its oligomerization, but rather, significantly disrupt mitochondrial network dynamics compared to wild-type MID51 in high spatial and temporal resolution confocal microscopy live imaging studies. Together, our study identifies dominant MIEF1 mutations as a cause for optic neuropathy and further highlights the important role of properly regulated mitochondrial dynamics in neurodegeneration.
Collapse
Affiliation(s)
- Majida Charif
- Université d’Angers, MitoLab team, UMR CNRS 6015 - INSERM U1083, Unité MitoVasc, Angers, France
- Genetics and Immuno-Cell Therapy Team, Mohammed First University, Oujda, Morocco
| | - Yvette C. Wong
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL USA
| | - Soojin Kim
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL USA
| | - Agnès Guichet
- Departments of Biochemistry and Genetics, University Hospital Angers, Angers, France
| | - Catherine Vignal
- Neuroophthalmology Department, Rothschild Ophthalmologic Foundation, Paris, France
| | - Xavier Zanlonghi
- Centre de Compétence Maladies Rares, Clinique Pluridisciplinaire Jules Verne, Nantes, France
| | | | - Vincent Procaccio
- Université d’Angers, MitoLab team, UMR CNRS 6015 - INSERM U1083, Unité MitoVasc, Angers, France
- Departments of Biochemistry and Genetics, University Hospital Angers, Angers, France
| | - Dominique Bonneau
- Université d’Angers, MitoLab team, UMR CNRS 6015 - INSERM U1083, Unité MitoVasc, Angers, France
- Departments of Biochemistry and Genetics, University Hospital Angers, Angers, France
| | - Patrizia Amati-Bonneau
- Université d’Angers, MitoLab team, UMR CNRS 6015 - INSERM U1083, Unité MitoVasc, Angers, France
- Departments of Biochemistry and Genetics, University Hospital Angers, Angers, France
| | - Pascal Reynier
- Université d’Angers, MitoLab team, UMR CNRS 6015 - INSERM U1083, Unité MitoVasc, Angers, France
- Departments of Biochemistry and Genetics, University Hospital Angers, Angers, France
| | - Dimitri Krainc
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL USA
| | - Guy Lenaers
- Université d’Angers, MitoLab team, UMR CNRS 6015 - INSERM U1083, Unité MitoVasc, Angers, France
| |
Collapse
|
50
|
Di Nottia M, Verrigni D, Torraco A, Rizza T, Bertini E, Carrozzo R. Mitochondrial Dynamics: Molecular Mechanisms, Related Primary Mitochondrial Disorders and Therapeutic Approaches. Genes (Basel) 2021; 12:genes12020247. [PMID: 33578638 PMCID: PMC7916359 DOI: 10.3390/genes12020247] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 02/02/2021] [Accepted: 02/04/2021] [Indexed: 02/06/2023] Open
Abstract
Mitochondria do not exist as individual entities in the cell—conversely, they constitute an interconnected community governed by the constant and opposite process of fission and fusion. The mitochondrial fission leads to the formation of smaller mitochondria, promoting the biogenesis of new organelles. On the other hand, following the fusion process, mitochondria appear as longer and interconnected tubules, which enhance the communication with other organelles. Both fission and fusion are carried out by a small number of highly conserved guanosine triphosphatase proteins and their interactors. Disruption of this equilibrium has been associated with several pathological conditions, ranging from cancer to neurodegeneration, and mutations in genes involved in mitochondrial fission and fusion have been reported to be the cause of a subset of neurogenetic disorders.
Collapse
|