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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.
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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
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2
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Borrelli E, Bandello F, Boon CJF, Carelli V, Lenaers G, Reibaldi M, Sadda SR, Sadun AA, Sarraf D, Yu-Wai-Man P, Barboni P. Mitochondrial retinopathies and optic neuropathies: The impact of retinal imaging on modern understanding of pathogenesis, diagnosis, and management. Prog Retin Eye Res 2024; 101:101264. [PMID: 38703886 DOI: 10.1016/j.preteyeres.2024.101264] [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: 01/11/2024] [Revised: 03/18/2024] [Accepted: 04/26/2024] [Indexed: 05/06/2024]
Abstract
Advancements in ocular imaging have significantly broadened our comprehension of mitochondrial retinopathies and optic neuropathies by examining the structural and pathological aspects of the retina and optic nerve in these conditions. This article aims to review the prominent imaging characteristics associated with mitochondrial retinopathies and optic neuropathies, aiming to deepen our insight into their pathogenesis and clinical features. Preceding this exploration, the article provides a detailed overview of the crucial genetic and clinical features, which is essential for the proper interpretation of in vivo imaging. More importantly, we will provide a critical analysis on how these imaging modalities could serve as biomarkers for characterization and monitoring, as well as in guiding treatment decisions. However, these imaging methods have limitations, which will be discussed along with potential strategies to mitigate them. Lastly, the article will emphasize the potential advantages and future integration of imaging techniques in evaluating patients with mitochondrial eye disorders, considering the prospects of emerging gene therapies.
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Affiliation(s)
- Enrico Borrelli
- Department of Surgical Sciences, University of Turin, Turin, Italy; Department of Ophthalmology, "City of Health and Science" Hospital, Turin, Italy.
| | - Francesco Bandello
- Vita-Salute San Raffaele University, Milan, Italy; IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Camiel J F Boon
- Department of Ophthalmology, Amsterdam University Medical Centers, Amsterdam, the Netherlands; Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
| | - Valerio Carelli
- Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Bologna, Italy; IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, Bologna, Italy
| | - Guy Lenaers
- Equipe MitoLab, Unité MitoVasc, INSERM U1083, Université d'Angers, 49933, Angers, France; Service de Neurologie, CHU d'Angers, 49100, Angers, France
| | - Michele Reibaldi
- Department of Surgical Sciences, University of Turin, Turin, Italy; Department of Ophthalmology, "City of Health and Science" Hospital, Turin, Italy
| | - Srinivas R Sadda
- Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Doheny Eye Institute, Los Angeles, CA, USA
| | - Alfredo A Sadun
- Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Doheny Eye Institute, Los Angeles, CA, USA
| | - David Sarraf
- Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Retinal Disorders and Ophthalmic Genetics Division, Stein Eye Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Patrick Yu-Wai-Man
- John van Geest 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 NHS Foundation Trust, London, UK; Institute of Ophthalmology, University College London, London, UK
| | - Piero Barboni
- IRCCS San Raffaele Scientific Institute, Milan, Italy; Studio Oculistico d'Azeglio, Bologna, Italy.
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Liu YF, Luo XY, Zhao ZC, Zheng W, Lv HY, Luo WM. Association between optic atrophy 1 polymorphisms and primary open angle glaucoma risk: Based on a meta-analysis. Eur J Ophthalmol 2024; 34:708-718. [PMID: 37872653 DOI: 10.1177/11206721231208244] [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] [Indexed: 10/25/2023]
Abstract
BACKGROUND Emerging evidence suggested a significant association between optic atrophy 1 (OPA1) polymorphisms and primary open angle glaucoma (POAG) risk. However, the current data are inconsistent or even contradictory. Given these, we conducted a meta-analysis to examine the precise association between OPA1 polymorphisms and POAG risk. MATERIALS AND METHODS Online databases were retrieved, and the related studies were reviewed from inception to December 1, 2022. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were calculated to examine the statistical power of each genetic model. In addition, heterogeneity, sensitivity, cumulative analysis, and publication bias were analyzed to guarantee statistical power. RESULT Overall, 14 studies within 11 publications (involving 2,413 POAG patients and 1,904 controls) were included and some significant association between OPA1 rs166850 C/T (T vs. C: OR = 1.24, 95%CI = 1.06-1.45, P = 0.01, I2 = 39.0%; CT vs. CC: OR = 1.37, 95%CI = 1.05-1.79, P = 0.02, I2 = 41.6%; CT + TT vs. CC: 1.37, 95%CI = 1.06-1.77, P = 0.02, I2 = 41.6%), rs10451941T/C (TC + CC vs. TT: OR = 1.79, 95%CI = 1.41-2.28, P < 0.01, I2 = 71.9%) polymorphisms and POAG susceptibility. In addition, further significant associations were also observed in the stratified analysis, especially in normal tension glaucoma groups and Caucasian descendants. CONCLUSION The observed evidences suggest that OPA1 polymorphisms may be associate with POAG susceptibility significantly.
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Affiliation(s)
- Yue-Feng Liu
- Department of Ophthalmology, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, China
| | - Xiang-Yu Luo
- Department of Cardiothoracic Surgery, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, China
| | - Zhi-Cai Zhao
- Department of Pulmonary and Critical Care Medicine, Wudang Mountain Campus of Taihe Hospital Shiyan, Shiyan, Hubei, China
| | - Wu Zheng
- Department of Ophthalmology, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, China
| | - Hai-Yang Lv
- Department of Ophthalmology, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, China
| | - Wei-Min Luo
- Department of Cardiothoracic Surgery, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, China
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Triolo M, Baker N, Agarwal S, Larionov N, Podinić T, Khacho M. Optic atrophy 1 mediates muscle differentiation by promoting a metabolic switch via the supercomplex assembly factor SCAF1. iScience 2024; 27:109164. [PMID: 38414856 PMCID: PMC10897915 DOI: 10.1016/j.isci.2024.109164] [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: 08/25/2023] [Revised: 12/08/2023] [Accepted: 02/05/2024] [Indexed: 02/29/2024] Open
Abstract
Myogenic differentiation is integral for the regeneration of skeletal muscle following tissue damage. Though high-energy post-mitotic muscle relies predominantly on mitochondrial respiration, the importance of mitochondrial remodeling in enabling muscle differentiation and the players involved are not fully known. Here we show that the mitochondrial fusion protein OPA1 is essential for muscle differentiation. Our study demonstrates that OPA1 loss or inhibition, through genetic and pharmacological means, abolishes in vivo muscle regeneration and in vitro myotube formation. We show that both the inhibition and genetic deletion of OPA1 prevent the early onset metabolic switch required to drive myoblast differentiation. In addition, we observe an OPA1-dependent upregulation of the supercomplex assembly factor, SCAF1, at the onset of differentiation. Importantly, preventing the upregulation of SCAF1, through OPA1 loss or siRNA-mediated SCAF1 knockdown, impairs metabolic reprogramming and muscle differentiation. These findings reveal the integral role of OPA1 and mitochondrial reprogramming at the onset of myogenic differentiation.
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Affiliation(s)
- Matthew Triolo
- Department of Biochemistry, Microbiology and Immunology, Center for Neuromuscular Disease (CNMD), Ottawa Institute of Systems Biology (OISB), Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Nicole Baker
- Department of Biochemistry, Microbiology and Immunology, Center for Neuromuscular Disease (CNMD), Ottawa Institute of Systems Biology (OISB), Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Soniya Agarwal
- Department of Biochemistry, Microbiology and Immunology, Center for Neuromuscular Disease (CNMD), Ottawa Institute of Systems Biology (OISB), Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Nikita Larionov
- Department of Biochemistry, Microbiology and Immunology, Center for Neuromuscular Disease (CNMD), Ottawa Institute of Systems Biology (OISB), Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Tina Podinić
- Department of Biochemistry, Microbiology and Immunology, Center for Neuromuscular Disease (CNMD), Ottawa Institute of Systems Biology (OISB), Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Mireille Khacho
- Department of Biochemistry, Microbiology and Immunology, Center for Neuromuscular Disease (CNMD), Ottawa Institute of Systems Biology (OISB), Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
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Da Dalt L, Moregola A, Svecla M, Pedretti S, Fantini F, Ronzio M, Uboldi P, Dolfini D, Donetti E, Baragetti A, Mitro N, Scorrano L, Norata GD. The inhibition of inner mitochondrial fusion in hepatocytes reduces non-alcoholic fatty liver and improves metabolic profile during obesity by modulating bile acid conjugation. Cardiovasc Res 2024; 119:2917-2929. [PMID: 37922889 DOI: 10.1093/cvr/cvad169] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 07/14/2023] [Accepted: 08/25/2023] [Indexed: 11/07/2023] Open
Abstract
AIMS Mitochondria are plastic organelles that continuously undergo biogenesis, fusion, fission, and mitophagy to control cellular energy metabolism, calcium homeostasis, hormones, sterols, and bile acids (BAs) synthesis. Here, we evaluated how the impairment of mitochondrial fusion in hepatocytes affects diet-induced liver steatosis and obesity. METHODS AND RESULTS Male mice selectively lacking the key protein involved in inner mitochondrial fusion, optic atrophy 1 (OPA1) (OPA1ΔHep) were fed a high fat diet (HFD) for 20 weeks. OPA1ΔHep mice were protected from the development of hepatic steatosis and obesity because of reduced lipid absorption; a profile which was accompanied by increased respiratory exchange ratio in vivo, suggesting a preference for carbohydrates in OPA1ΔHep compared to controls. At the molecular level, this phenotype emerged as a consequence of poor mitochondria-peroxisome- endoplasmic reticulum (ER) tethering in OPA1 deficient hepatocytes, which impaired BAs conjugation and release in the bile, thus impacting lipid absorption from the diet. Concordantly, the liver of subjects with non-alcoholic fatty liver disease (NAFLD) presented an increased expression of OPA1 and of the network of proteins involved in mitochondrial function when compared with controls. CONCLUSION Patients with NAFLD present increased expression of proteins involved in mitochondrial fusion in the liver. The selective deficency of OPA1 in hepatocytes protects mice from HFD-induced metabolic dysfunction by reducing BAs secretion and dietary lipids absorption as a consequence of reduced liver mitochondria-peroxisome-ER tethering.
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Affiliation(s)
- Lorenzo Da Dalt
- Department of Pharmacological and Biomolecular Sciences "Rodolfo Paoletti", Università Degli Studi di Milano, Via Balzaretti 9, 20133 Milan, Italy
| | - Annalisa Moregola
- Department of Pharmacological and Biomolecular Sciences "Rodolfo Paoletti", Università Degli Studi di Milano, Via Balzaretti 9, 20133 Milan, Italy
| | - Monika Svecla
- Department of Pharmacological and Biomolecular Sciences "Rodolfo Paoletti", Università Degli Studi di Milano, Via Balzaretti 9, 20133 Milan, Italy
| | - Silvia Pedretti
- Department of Pharmacological and Biomolecular Sciences "Rodolfo Paoletti", Università Degli Studi di Milano, Via Balzaretti 9, 20133 Milan, Italy
| | - Francesca Fantini
- Department of Pharmacological and Biomolecular Sciences "Rodolfo Paoletti", Università Degli Studi di Milano, Via Balzaretti 9, 20133 Milan, Italy
| | - Mirko Ronzio
- Dipartiment of Biosciences, Università Degli Studi di Milano,Via Celoria 26, 20133 Milan, Italy
| | - Patrizia Uboldi
- Department of Pharmacological and Biomolecular Sciences "Rodolfo Paoletti", Università Degli Studi di Milano, Via Balzaretti 9, 20133 Milan, Italy
| | - Diletta Dolfini
- Dipartiment of Biosciences, Università Degli Studi di Milano,Via Celoria 26, 20133 Milan, Italy
| | - Elena Donetti
- Department of Biomedical Science for Health, Università Degli Studi di Milano, Via Mangiagalli, 31, 20133 Milan, Italy
| | - Andrea Baragetti
- Department of Pharmacological and Biomolecular Sciences "Rodolfo Paoletti", Università Degli Studi di Milano, Via Balzaretti 9, 20133 Milan, Italy
| | - Nico Mitro
- Department of Pharmacological and Biomolecular Sciences "Rodolfo Paoletti", Università Degli Studi di Milano, Via Balzaretti 9, 20133 Milan, Italy
- Department of Experimental Oncology, IEO, European Institute of Oncology IRCCS, Milan, Italy
| | - Luca Scorrano
- Department of Biology, University of Padova, Via U. Bassi 58B, 35121 Padova, Italy
- Veneto Institute of Molecular Medicine, Via Orus 2, 35129 Padova, Italy
| | - Giuseppe Danilo Norata
- Department of Pharmacological and Biomolecular Sciences "Rodolfo Paoletti", Università Degli Studi di Milano, Via Balzaretti 9, 20133 Milan, Italy
- Center for the Study of Atherosclerosis, E. Bassini Hospital, Via Massimo Gorki 50, Cinisello Balsamo, Italy
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Affortit C, Coyat C, Saidia AR, Ceccato JC, Charif M, Sarzi E, Flamant F, Guyot R, Cazevieille C, Puel JL, Lenaers G, Wang J. The human OPA1 delTTAG mutation induces adult onset and progressive auditory neuropathy in mice. Cell Mol Life Sci 2024; 81:80. [PMID: 38334784 PMCID: PMC10858076 DOI: 10.1007/s00018-024-05115-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 01/05/2024] [Accepted: 01/05/2024] [Indexed: 02/10/2024]
Abstract
Dominant optic atrophy (DOA) is one of the most prevalent forms of hereditary optic neuropathies and is mainly caused by heterozygous variants in OPA1, encoding a mitochondrial dynamin-related large GTPase. The clinical spectrum of DOA has been extended to a wide variety of syndromic presentations, called DOAplus, including deafness as the main secondary symptom associated to vision impairment. To date, the pathophysiological mechanisms underlying the deafness in DOA remain unknown. To gain insights into the process leading to hearing impairment, we have analyzed the Opa1delTTAG mouse model that recapitulates the DOAplus syndrome through complementary approaches combining morpho-physiology, biochemistry, and cellular and molecular biology. We found that Opa1delTTAG mutation leads an adult-onset progressive auditory neuropathy in mice, as attested by the auditory brainstem response threshold shift over time. However, the mutant mice harbored larger otoacoustic emissions in comparison to wild-type littermates, whereas the endocochlear potential, which is a proxy for the functional state of the stria vascularis, was comparable between both genotypes. Ultrastructural examination of the mutant mice revealed a selective loss of sensory inner hair cells, together with a progressive degeneration of the axons and myelin sheaths of the afferent terminals of the spiral ganglion neurons, supporting an auditory neuropathy spectrum disorder (ANSD). Molecular assessment of cochlea demonstrated a reduction of Opa1 mRNA level by greater than 40%, supporting haploinsufficiency as the disease mechanism. In addition, we evidenced an early increase in Sirtuin 3 level and in Beclin1 activity, and subsequently an age-related mtDNA depletion, increased oxidative stress, mitophagy as well as an impaired autophagic flux. Together, these results support a novel role for OPA1 in the maintenance of inner hair cells and auditory neural structures, addressing new challenges for the exploration and treatment of OPA1-linked ANSD in patients.
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Affiliation(s)
- Corentin Affortit
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, UMR 1298, 80 Rue Augustin Fliche, 34295, Montpellier, France
- Molecular Otolaryngology and Renal Research Laboratories, Department of Otolaryngology, Head and Neck Surgery, University of Iowa, Iowa City, IA, 52242, USA
| | - Carolanne Coyat
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, UMR 1298, 80 Rue Augustin Fliche, 34295, Montpellier, France
| | - Anissa Rym Saidia
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, UMR 1298, 80 Rue Augustin Fliche, 34295, Montpellier, France
| | - Jean-Charles Ceccato
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, UMR 1298, 80 Rue Augustin Fliche, 34295, Montpellier, France
| | - Majida Charif
- Genetics, and Immuno-Cell Therapy Team, Mohamed First University, 60000, Oujda, Morocco
| | - Emmanuelle Sarzi
- Institut NeuroMyoGène, Pathophysiology and Genetics of Neuron and Muscle (INMG-PGNM) UCBL-CNRS UMR5261, Inserm U1315, Université Claude Bernard, Lyon I, Faculty of Medicine and Pharmacy, Lyon, France
| | - Frédéric Flamant
- Institut de Génomique Fonctionnelle de Lyon (IGFL), INRAE USC1370, CNRS (UMR5242), ENS Lyon, Lyon, France
| | - Romain Guyot
- Institut de Génomique Fonctionnelle de Lyon (IGFL), INRAE USC1370, CNRS (UMR5242), ENS Lyon, Lyon, France
| | - Chantal Cazevieille
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, UMR 1298, 80 Rue Augustin Fliche, 34295, Montpellier, France
| | - Jean-Luc Puel
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, UMR 1298, 80 Rue Augustin Fliche, 34295, Montpellier, France
| | - Guy Lenaers
- Université Angers, MitoLab Team, Unité MitoVasc, UMR CNRS 6015, INSERM U1083, SFR ICAT, Angers, France
- Service de Neurologie, CHU d'Angers, Angers, France
| | - Jing Wang
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, UMR 1298, 80 Rue Augustin Fliche, 34295, Montpellier, France.
- Department of ENT and Head and Neck Surgery, University Hospital of Montpellier, Montpellier, France.
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Madhu V, Hernandaz-Meadows M, Coleman A, Sao K, Inguito K, Haslam O, Boneski PK, Sesaki H, Collins JA, Risbud MV. OPA1 protects intervertebral disc and knee joint health in aged mice by maintaining the structure and metabolic functions of mitochondria. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.17.576115. [PMID: 38293153 PMCID: PMC10827164 DOI: 10.1101/2024.01.17.576115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Due to their glycolytic nature and limited vascularity, nucleus pulposus (NP) cells of the intervertebral disc and articular chondrocytes were long thought to have minimal reliance on mitochondrial function. Recent studies have challenged this long-held view and highlighted the increasingly important role of mitochondria in the physiology of these tissues. We investigated the role of mitochondrial fusion protein OPA1 in maintaining the spine and knee joint health in aging mice. OPA1 knockdown in NP cells altered mitochondrial size and cristae shape and increased the oxygen consumption rate without affecting ATP synthesis. OPA1 governed the morphology of multiple organelles, and its loss resulted in the dysregulation of NP cell autophagy. Metabolic profiling and 13 C-flux analyses revealed TCA cycle anaplerosis and altered metabolism in OPA1-deficient NP cells. Noteworthy, Opa1 AcanCreERT2 mice showed age- dependent disc, and cartilage degeneration and vertebral osteopenia. Our findings suggest that OPA1 regulation of mitochondrial dynamics and multi-organelle interactions is critical in preserving metabolic homeostasis of disc and cartilage. Teaser OPA1 is necessary for the maintenance of intervertebral disc and knee joint health in aging mice.
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Feng Z, Lai R, Wei J, Liu X, Chen X, Liu Y, Qin W, Qin X, Kong F. Have one's view of the important overshadowed by the trivial: chronic progressive external ophthalmoplegia combined with unilateral facial nerve injury: a case report and literature review. Front Neurol 2024; 14:1268053. [PMID: 38249737 PMCID: PMC10797034 DOI: 10.3389/fneur.2023.1268053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 12/05/2023] [Indexed: 01/23/2024] Open
Abstract
Chronic progressive external ophthalmoplegia (CPEO) is a mitochondrial encephalomyopathy that is characterized by progressive ptosis and impaired ocular motility. Owing to its nonspecific clinical manifestations, CPEO is often misdiagnosed as other conditions. Herein, we present the case of a 34-year-old woman who primarily presented with incomplete left eyelid closure and limited bilateral eye movements. During the 6-year disease course, she was diagnosed with myasthenia gravis and cranial polyneuritis. Finally, skeletal muscle tissue biopsy confirmed the diagnosis. Biopsy revealed pathological changes in mitochondrial myopathy. Furthermore, mitochondrial gene testing of the skeletal muscle revealed a single chrmM:8469-13447 deletion. In addition, we summarized the findings of 26 patients with CPEO/Kearns-Sayre syndrome who were misdiagnosed with other diseases owing to ocular symptoms. In conclusion, we reported a rare clinical case and emphasized the symptomatic diversity of CPEO. Furthermore, we provided a brief review of the diagnosis and differential diagnosis of the disease.
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Affiliation(s)
- Ziyang Feng
- The Fourth Clinical Medical College, Guangzhou University of Chinese Medicine, Shenzhen, China
| | - Rui Lai
- School of Acupuncture and Tuina, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Jia Wei
- The Fourth Clinical Medical College, Guangzhou University of Chinese Medicine, Shenzhen, China
- Department of Encephalopathy and Psychology, Shenzhen Traditional Chinese Medicine Hospital, Shenzhen, China
| | - Xuan Liu
- The Fourth Clinical Medical College, Guangzhou University of Chinese Medicine, Shenzhen, China
- Department of Encephalopathy and Psychology, Shenzhen Traditional Chinese Medicine Hospital, Shenzhen, China
| | - Xueqin Chen
- The Fourth Clinical Medical College, Guangzhou University of Chinese Medicine, Shenzhen, China
- Department of Encephalopathy and Psychology, Shenzhen Traditional Chinese Medicine Hospital, Shenzhen, China
| | - Yangsicheng Liu
- The Fourth Clinical Medical College, Guangzhou University of Chinese Medicine, Shenzhen, China
| | - Wenxin Qin
- The Fourth Clinical Medical College, Guangzhou University of Chinese Medicine, Shenzhen, China
| | - Xiude Qin
- The Fourth Clinical Medical College, Guangzhou University of Chinese Medicine, Shenzhen, China
- Department of Encephalopathy and Psychology, Shenzhen Traditional Chinese Medicine Hospital, Shenzhen, China
| | - Fanxin Kong
- The Fourth Clinical Medical College, Guangzhou University of Chinese Medicine, Shenzhen, China
- Department of Encephalopathy and Psychology, Shenzhen Traditional Chinese Medicine Hospital, Shenzhen, China
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9
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Ilamathi HS, Germain M. ER-mitochondria contact sites in mitochondrial DNA dynamics, maintenance, and distribution. Int J Biochem Cell Biol 2024; 166:106492. [PMID: 37931682 DOI: 10.1016/j.biocel.2023.106492] [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: 07/24/2023] [Revised: 10/08/2023] [Accepted: 11/03/2023] [Indexed: 11/08/2023]
Abstract
Mitochondria are central cellular metabolic hubs. Their function requires proteins encoded by nuclear DNA, but also mitochondrial DNA (mtDNA) whose maintenance is essential for the proper function of the organelle. Defective mtDNA maintenance and distribution are associated with mitochondrial diseases. mtDNA is organized into nucleo-protein complexes called nucleoids that dynamically move along the mitochondrial network and interact with each other. mtDNA replication and nucleoid distribution is an active process regulated by the complex interplay of mitochondrial dynamics, endoplasmic reticulum (ER)-mitochondria contact sites, and cytoskeletal networks. For example, defects in mitochondrial fusion and fission or ER-mitochondria contact sites affect nucleoid maintenance and distribution. In this review, we discuss the process of nucleoid dynamics and the factors regulating nucleoid maintenance and distribution.
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Affiliation(s)
- Hema Saranya Ilamathi
- Groupe de Recherche en Signalisation Cellulaire and Département de Biologie Médicale, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada; Centre d'Excellence en Recherche sur les Maladies Orphelines - Fondation Courtois, Université du Québec à Montréal, Montréal, Québec, Canada; Réseau Intersectoriel de Recherche en Santé de l'Université du Québec (RISUQ), Canada.
| | - Marc Germain
- Groupe de Recherche en Signalisation Cellulaire and Département de Biologie Médicale, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada; Centre d'Excellence en Recherche sur les Maladies Orphelines - Fondation Courtois, Université du Québec à Montréal, Montréal, Québec, Canada; Réseau Intersectoriel de Recherche en Santé de l'Université du Québec (RISUQ), Canada
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10
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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.
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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
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11
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Lee H, Lee TJ, Galloway CA, Zhi W, Xiao W, de Mesy Bentley KL, Sharma A, Teng Y, Sesaki H, Yoon Y. The mitochondrial fusion protein OPA1 is dispensable in the liver and its absence induces mitohormesis to protect liver from drug-induced injury. Nat Commun 2023; 14:6721. [PMID: 37872238 PMCID: PMC10593833 DOI: 10.1038/s41467-023-42564-0] [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: 02/14/2023] [Accepted: 10/13/2023] [Indexed: 10/25/2023] Open
Abstract
Mitochondria are critical for metabolic homeostasis of the liver, and their dysfunction is a major cause of liver diseases. Optic atrophy 1 (OPA1) is a mitochondrial fusion protein with a role in cristae shaping. Disruption of OPA1 causes mitochondrial dysfunction. However, the role of OPA1 in liver function is poorly understood. In this study, we delete OPA1 in the fully developed liver of male mice. Unexpectedly, OPA1 liver knockout (LKO) mice are healthy with unaffected mitochondrial respiration, despite disrupted cristae morphology. OPA1 LKO induces a stress response that establishes a new homeostatic state for sustained liver function. Our data show that OPA1 is required for proper complex V assembly and that OPA1 LKO protects the liver from drug toxicity. Mechanistically, OPA1 LKO decreases toxic drug metabolism and confers resistance to the mitochondrial permeability transition. This study demonstrates that OPA1 is dispensable in the liver, and that the mitohormesis induced by OPA1 LKO prevents liver injury and contributes to liver resiliency.
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Affiliation(s)
- Hakjoo Lee
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA
| | - Tae Jin Lee
- Center for Biotechnology and Genomic Medicine, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA
| | - Chad A Galloway
- Department of Pathology and Laboratory Medicine, and Center for Advanced Research Technologies, University of Rochester Medical Center, Rochester, NY, 14642, USA
| | - Wenbo Zhi
- Center for Biotechnology and Genomic Medicine, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA
| | - Wei Xiao
- Center for Biotechnology and Genomic Medicine, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA
| | - Karen L de Mesy Bentley
- Department of Pathology and Laboratory Medicine, and Center for Advanced Research Technologies, University of Rochester Medical Center, Rochester, NY, 14642, USA
| | - Ashok Sharma
- Center for Biotechnology and Genomic Medicine, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA
| | - Yong Teng
- Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Hiromi Sesaki
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Yisang Yoon
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA.
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12
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Hu D, Tan M, Lu D, Kleiboeker B, Liu X, Park H, Kravitz AV, Shoghi KI, Tseng YH, Razani B, Ikeda A, Lodhi IJ. TMEM135 links peroxisomes to the regulation of brown fat mitochondrial fission and energy homeostasis. Nat Commun 2023; 14:6099. [PMID: 37773161 PMCID: PMC10541902 DOI: 10.1038/s41467-023-41849-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 09/20/2023] [Indexed: 10/01/2023] Open
Abstract
Mitochondrial morphology, which is controlled by mitochondrial fission and fusion, is an important regulator of the thermogenic capacity of brown adipocytes. Adipose-specific peroxisome deficiency impairs thermogenesis by inhibiting cold-induced mitochondrial fission due to decreased mitochondrial membrane content of the peroxisome-derived lipids called plasmalogens. Here, we identify TMEM135 as a critical mediator of the peroxisomal regulation of mitochondrial fission and thermogenesis. Adipose-specific TMEM135 knockout in mice blocks mitochondrial fission, impairs thermogenesis, and increases diet-induced obesity and insulin resistance. Conversely, TMEM135 overexpression promotes mitochondrial division, counteracts obesity and insulin resistance, and rescues thermogenesis in peroxisome-deficient mice. Mechanistically, thermogenic stimuli promote association between peroxisomes and mitochondria and plasmalogen-dependent localization of TMEM135 in mitochondria, where it mediates PKA-dependent phosphorylation and mitochondrial retention of the fission factor Drp1. Together, these results reveal a previously unrecognized inter-organelle communication regulating mitochondrial fission and energy homeostasis and identify TMEM135 as a potential target for therapeutic activation of BAT.
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Affiliation(s)
- Donghua Hu
- Division of Endocrinology, Metabolism & Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Min Tan
- Division of Endocrinology, Metabolism & Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Dongliang Lu
- Division of Endocrinology, Metabolism & Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Brian Kleiboeker
- Division of Endocrinology, Metabolism & Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Xuejing Liu
- Division of Endocrinology, Metabolism & Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Hongsuk Park
- Division of Endocrinology, Metabolism & Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Alexxai V Kravitz
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO, USA
| | - Kooresh I Shoghi
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Yu-Hua Tseng
- Section on Integrative Physiology and Metabolism, Research Division, Joslin Diabetes Center, Harvard Medical School, Boston, MA, USA
| | - Babak Razani
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
- University of Pittsburgh School of Medicine and UPMC, Pittsburgh, PA, USA
| | - Akihiro Ikeda
- Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI, USA
| | - Irfan J Lodhi
- Division of Endocrinology, Metabolism & Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA.
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13
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Pohl KA, Zhang X, Pham AH, Chan JW, Sadun AA, Yang XJ. Establishing induced pluripotent stem cell lines from two dominant optic atrophy patients with distinct OPA1 mutations and clinical pathologies. Front Genet 2023; 14:1251216. [PMID: 37745862 PMCID: PMC10513078 DOI: 10.3389/fgene.2023.1251216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Accepted: 08/17/2023] [Indexed: 09/26/2023] Open
Abstract
Dominant optic atrophy (DOA) is an inherited disease that leads to the loss of retinal ganglion cells (RGCs), the projection neurons that relay visual information from the retina to the brain through the optic nerve. The majority of DOA cases can be attributed to mutations in optic atrophy 1 (OPA1), a nuclear gene encoding a mitochondrial-targeted protein that plays important roles in maintaining mitochondrial structure, dynamics, and bioenergetics. Although OPA1 is ubiquitously expressed in all human tissues, RGCs appear to be the primary cell type affected by OPA1 mutations. DOA has not been extensively studied in human RGCs due to the general unavailability of retinal tissues. However, recent advances in stem cell biology have made it possible to produce human RGCs from pluripotent stem cells (PSCs). To aid in establishing DOA disease models based on human PSC-derived RGCs, we have generated iPSC lines from two DOA patients who carry distinct OPA1 mutations and present very different disease symptoms. Studies using these OPA1 mutant RGCs can be correlated with clinical features in the patients to provide insights into DOA disease mechanisms.
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Affiliation(s)
- Katherine A. Pohl
- Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA, United States
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA, United States
| | - Xiangmei Zhang
- Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA, United States
| | - Anh H. Pham
- Department of Ophthalmology, Doheny Eye Institute, University of California, Los Angeles, Pasadena, CA, United States
| | - Jane W. Chan
- Department of Ophthalmology, Doheny Eye Institute, University of California, Los Angeles, Pasadena, CA, United States
| | - Alfredo A. Sadun
- Department of Ophthalmology, Doheny Eye Institute, University of California, Los Angeles, Pasadena, CA, United States
| | - Xian-Jie Yang
- Department of Ophthalmology, Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA, United States
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA, United States
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14
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Millet AMC, Coustham C, Champigny C, Botella M, Demeilliers C, Devin A, Galinier A, Belenguer P, Bordeneuve-Guibé J, Davezac N. OPA1 deficiency impairs oxidative metabolism in cycling cells, underlining a translational approach for degenerative diseases. Dis Model Mech 2023; 16:dmm050266. [PMID: 37497665 PMCID: PMC10538295 DOI: 10.1242/dmm.050266] [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: 04/24/2023] [Accepted: 07/12/2023] [Indexed: 07/28/2023] Open
Abstract
Dominant optic atrophy is an optic neuropathy with varying clinical symptoms and progression. A severe disorder is associated with certain OPA1 mutations and includes additional symptoms for >20% of patients. This underscores the consequences of OPA1 mutations in different cellular populations, not only retinal ganglionic cells. We assessed the effects of OPA1 loss of function on oxidative metabolism and antioxidant defences using an RNA-silencing strategy in a human epithelial cell line. We observed a decrease in the mitochondrial respiratory chain complexes, associated with a reduction in aconitase activity related to an increase in reactive oxygen species (ROS) production. In response, the NRF2 (also known as NFE2L2) transcription factor was translocated into the nucleus and upregulated SOD1 and GSTP1. This study highlights the effects of OPA1 deficiency on oxidative metabolism in replicative cells, as already shown in neurons. It underlines a translational process to use cycling cells to circumvent and describe oxidative metabolism. Moreover, it paves the way to predict the evolution of dominant optic atrophy using mathematical models that consider mitochondrial ROS production and their detoxifying pathways.
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Affiliation(s)
- Aurélie M. C. Millet
- Research Center on Animal Cognition (CRCA), Center for Integrative Biology (CBI), Toulouse University, CNRS, UPS, 31400Toulouse, France
| | - Corentin Coustham
- Research Center on Animal Cognition (CRCA), Center for Integrative Biology (CBI), Toulouse University, CNRS, UPS, 31400Toulouse, France
- ISAE-SUPAERO, Toulouse University, 31400 Toulouse, France
| | - Camille Champigny
- Research Center on Animal Cognition (CRCA), Center for Integrative Biology (CBI), Toulouse University, CNRS, UPS, 31400Toulouse, France
| | - Marlène Botella
- Research Center on Animal Cognition (CRCA), Center for Integrative Biology (CBI), Toulouse University, CNRS, UPS, 31400Toulouse, France
| | | | - Anne Devin
- Laboratoire Métabolisme Energétique Cellulaire IBGC du CNRS, 1 rue Camille Saint Saëns, 33077 Bordeaux cedex, France
| | - Anne Galinier
- RESTORE – Université de Toulouse, CNRS ERL5311, EFS, INP-ENVT, Inserm U1031, UPS, Bâtiment INCERE, 4bis avenue Hubert Curien, 31100 Toulouse, France
| | - Pascale Belenguer
- Research Center on Animal Cognition (CRCA), Center for Integrative Biology (CBI), Toulouse University, CNRS, UPS, 31400Toulouse, France
| | | | - Noélie Davezac
- Research Center on Animal Cognition (CRCA), Center for Integrative Biology (CBI), Toulouse University, CNRS, UPS, 31400Toulouse, France
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15
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Dong H, Tsai SY. Mitochondrial Properties in Skeletal Muscle Fiber. Cells 2023; 12:2183. [PMID: 37681915 PMCID: PMC10486962 DOI: 10.3390/cells12172183] [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: 07/11/2023] [Revised: 08/16/2023] [Accepted: 08/24/2023] [Indexed: 09/09/2023] Open
Abstract
Mitochondria are the primary source of energy production and are implicated in a wide range of biological processes in most eukaryotic cells. Skeletal muscle heavily relies on mitochondria for energy supplements. In addition to being a powerhouse, mitochondria evoke many functions in skeletal muscle, including regulating calcium and reactive oxygen species levels. A healthy mitochondria population is necessary for the preservation of skeletal muscle homeostasis, while mitochondria dysregulation is linked to numerous myopathies. In this review, we summarize the recent studies on mitochondria function and quality control in skeletal muscle, focusing mainly on in vivo studies of rodents and human subjects. With an emphasis on the interplay between mitochondrial functions concerning the muscle fiber type-specific phenotypes, we also discuss the effect of aging and exercise on the remodeling of skeletal muscle and mitochondria properties.
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Affiliation(s)
- Han Dong
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117593, Singapore;
| | - Shih-Yin Tsai
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117593, Singapore;
- Healthy Longevity Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117456, Singapore
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16
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Chen BS, Harvey JP, Gilhooley MJ, Jurkute N, Yu-Wai-Man P. Mitochondria and the eye-manifestations of mitochondrial diseases and their management. Eye (Lond) 2023; 37:2416-2425. [PMID: 37185957 PMCID: PMC10397317 DOI: 10.1038/s41433-023-02523-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 01/31/2023] [Accepted: 04/04/2023] [Indexed: 05/17/2023] Open
Abstract
Historically, distinct mitochondrial syndromes were recognised clinically by their ocular features. Due to their predilection for metabolically active tissue, mitochondrial diseases frequently involve the eye, resulting in a range of ophthalmic manifestations including progressive external ophthalmoplegia, retinopathy and optic neuropathy, as well as deficiencies of the retrochiasmal visual pathway. With the wider availability of genetic testing in clinical practice, it is now recognised that genotype-phenotype correlations in mitochondrial diseases can be imprecise: many classic syndromes can be associated with multiple genes and genetic variants, and the same genetic variant can have multiple clinical presentations, including subclinical ophthalmic manifestations in individuals who are otherwise asymptomatic. Previously considered rare diseases with no effective treatments, considerable progress has been made in our understanding of mitochondrial diseases with new therapies emerging, in particular, gene therapy for inherited optic neuropathies.
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Affiliation(s)
- Benson S Chen
- John van Geest 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
| | - Joshua P Harvey
- Moorfields Eye Hospital NHS Foundation Trust, London, UK
- Institute of Ophthalmology, University College London, London, UK
| | - Michael J Gilhooley
- Moorfields Eye Hospital NHS Foundation Trust, London, UK
- Institute of Ophthalmology, University College London, London, UK
- The National Hospital for Neurology and Neurosurgery, Queen Square, University College London Hospitals NHS Foundation Trust, London, UK
| | - Neringa Jurkute
- Moorfields Eye Hospital NHS Foundation Trust, London, UK
- Institute of Ophthalmology, University College London, London, UK
- The National Hospital for Neurology and Neurosurgery, Queen Square, University College London Hospitals NHS Foundation Trust, London, UK
| | - Patrick Yu-Wai-Man
- John van Geest 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 NHS Foundation Trust, London, UK.
- Institute of Ophthalmology, University College London, London, UK.
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17
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Stavropoulos D, Grewal MK, Petriti B, Chau KY, Hammond CJ, Garway-Heath DF, Lascaratos G. The Role of Mitophagy in Glaucomatous Neurodegeneration. Cells 2023; 12:1969. [PMID: 37566048 PMCID: PMC10417839 DOI: 10.3390/cells12151969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Revised: 07/15/2023] [Accepted: 07/19/2023] [Indexed: 08/12/2023] Open
Abstract
This review aims to provide a better understanding of the emerging role of mitophagy in glaucomatous neurodegeneration, which is the primary cause of irreversible blindness worldwide. Increasing evidence from genetic and other experimental studies suggests that mitophagy-related genes are implicated in the pathogenesis of glaucoma in various populations. The association between polymorphisms in these genes and increased risk of glaucoma is presented. Reduction in intraocular pressure (IOP) is currently the only modifiable risk factor for glaucoma, while clinical trials highlight the inadequacy of IOP-lowering therapeutic approaches to prevent sight loss in many glaucoma patients. Mitochondrial dysfunction is thought to increase the susceptibility of retinal ganglion cells (RGCs) to other risk factors and is implicated in glaucomatous degeneration. Mitophagy holds a vital role in mitochondrial quality control processes, and the current review explores the mitophagy-related pathways which may be linked to glaucoma and their therapeutic potential.
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Affiliation(s)
- Dimitrios Stavropoulos
- Department of Ophthalmology, King’s College Hospital, London SE5 9RS, UK;
- Department of Ophthalmology, 417 Veterans Army Hospital (NIMTS), 11521 Athens, Greece
| | - Manjot K. Grewal
- NIHR Biomedical Research Center, Moorfields Eye Hospital and UCL Institute of Ophthalmology, London EC1V 9EL, UK
- Division of Optometry and Visual Science, School of Health Sciences, City, University of London, London EC1V 0HB, UK
| | - Bledi Petriti
- NIHR Biomedical Research Center, Moorfields Eye Hospital and UCL Institute of Ophthalmology, London EC1V 9EL, UK
- Department of Clinical & Movement Neurosciences, UCL Queens Square Institute of Neurology, London NW3 2PF, UK
| | - Kai-Yin Chau
- Department of Clinical & Movement Neurosciences, UCL Queens Square Institute of Neurology, London NW3 2PF, UK
| | - Christopher J. Hammond
- Section of Ophthalmology, School of Life Course Sciences, King’s College London, London SE1 7EH, UK
- Department of Ophthalmology, St Thomas’ Hospital, London SE1 7EH, UK
| | - David F. Garway-Heath
- NIHR Biomedical Research Center, Moorfields Eye Hospital and UCL Institute of Ophthalmology, London EC1V 9EL, UK
| | - Gerassimos Lascaratos
- Department of Ophthalmology, King’s College Hospital, London SE5 9RS, UK;
- Section of Ophthalmology, School of Life Course Sciences, King’s College London, London SE1 7EH, UK
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18
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Picca A, Guerra F, Calvani R, Romano R, Coelho-Junior HJ, Bucci C, Leeuwenburgh C, Marzetti E. Mitochondrial-derived vesicles in skeletal muscle remodeling and adaptation. Semin Cell Dev Biol 2023; 143:37-45. [PMID: 35367122 DOI: 10.1016/j.semcdb.2022.03.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 02/25/2022] [Accepted: 03/19/2022] [Indexed: 12/24/2022]
Abstract
Mitochondrial remodeling is crucial to meet the bioenergetic demand to support muscle contractile activity during daily tasks and muscle regeneration following injury. A set of mitochondrial quality control (MQC) processes, including mitochondrial biogenesis, dynamics, and mitophagy, are in place to maintain a well-functioning mitochondrial network and support muscle regeneration. Alterations in any of these pathways compromises mitochondrial quality and may potentially lead to impaired myogenesis, defective muscle regeneration, and ultimately loss of muscle function. Among MQC processes, mitophagy has gained special attention for its implication in the clearance of dysfunctional mitochondria via crosstalk with the endo-lysosomal system, a major cell degradative route. Along this pathway, additional opportunities for mitochondrial disposal have been identified that may also signal at the systemic level. This communication occurs via inclusion of mitochondrial components within membranous shuttles named mitochondrial-derived vesicles (MDVs). Here, we discuss MDV generation and release as a mitophagy-complementing route for the maintenance of mitochondrial homeostasis in skeletal myocytes. We also illustrate the possible role of muscle-derived MDVs in immune signaling during muscle remodeling and adaptation.
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Affiliation(s)
- Anna Picca
- Fondazione Policlinico Universitario "Agostino Gemelli" IRCCS, Rome, Italy
| | - Flora Guerra
- Department of Biological and Environmental Sciences and Technologies, Università del Salento, Lecce, Italy
| | - Riccardo Calvani
- Fondazione Policlinico Universitario "Agostino Gemelli" IRCCS, Rome, Italy
| | - Roberta Romano
- Department of Biological and Environmental Sciences and Technologies, Università del Salento, Lecce, Italy
| | | | - Cecilia Bucci
- Department of Biological and Environmental Sciences and Technologies, Università del Salento, Lecce, Italy
| | - Christiaan Leeuwenburgh
- Department of Aging and Geriatric Research, Institute on Aging, Division of Biology of Aging, University of Florida, Gainesville, USA
| | - Emanuele Marzetti
- Fondazione Policlinico Universitario "Agostino Gemelli" IRCCS, Rome, Italy; Università Cattolica del Sacro Cuore, Department of Geriatrics and Orthopedics, Rome, Italy.
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19
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Implications of mitochondrial fusion and fission in skeletal muscle mass and health. Semin Cell Dev Biol 2023; 143:46-53. [PMID: 35168898 DOI: 10.1016/j.semcdb.2022.02.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 01/17/2022] [Accepted: 02/08/2022] [Indexed: 12/12/2022]
Abstract
The continuous dynamic reshaping of mitochondria by fusion and fission events is critical to keep mitochondrial quality and function under control in response to changes in energy and stress. Maintaining a functional, highly interconnected mitochondrial reticulum ensures rapid energy production and distribution. Moreover, mitochondrial networks act as dynamic signaling hub to adapt to the metabolic demands imposed by contraction, energy expenditure, and general metabolism. However, excessive mitochondrial fusion or fission results in the disruption of the skeletal muscle mitochondrial network integrity and activates a retrograde response from mitochondria to the nucleus, leading to muscle atrophy, weakness and influencing whole-body homeostasis. These actions are mediated via the secretion of mitochondrial-stress myokines such as FGF21 and GDF15. Here we will summarize recent discoveries in the role of mitochondrial fusion and fission in the control of muscle mass and in regulating physiological homeostasis and disease progression.
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20
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Magistrati M, Gilea AI, Gerra MC, Baruffini E, Dallabona C. Drug Drop Test: How to Quickly Identify Potential Therapeutic Compounds for Mitochondrial Diseases Using Yeast Saccharomyces cerevisiae. Int J Mol Sci 2023; 24:10696. [PMID: 37445873 DOI: 10.3390/ijms241310696] [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: 05/30/2023] [Revised: 06/22/2023] [Accepted: 06/25/2023] [Indexed: 07/15/2023] Open
Abstract
Mitochondrial diseases (MDs) refer to a group of clinically and genetically heterogeneous pathologies characterized by defective mitochondrial function and energy production. Unfortunately, there is no effective treatment for most MDs, and current therapeutic management is limited to relieving symptoms. The yeast Saccharomyces cerevisiae has been efficiently used as a model organism to study mitochondria-related disorders thanks to its easy manipulation and well-known mitochondrial biogenesis and metabolism. It has been successfully exploited both to validate alleged pathogenic variants identified in patients and to discover potential beneficial molecules for their treatment. The so-called "drug drop test", a phenotype-based high-throughput screening, especially if coupled with a drug repurposing approach, allows the identification of molecules with high translational potential in a cost-effective and time-saving manner. In addition to drug identification, S. cerevisiae can be used to point out the drug's target or pathway. To date, drug drop tests have been successfully carried out for a variety of disease models, leading to very promising results. The most relevant aspect is that studies on more complex model organisms confirmed the effectiveness of the drugs, strengthening the results obtained in yeast and demonstrating the usefulness of this screening as a novel approach to revealing new therapeutic molecules for MDs.
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Affiliation(s)
- Martina Magistrati
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy
| | - Alexandru Ionut Gilea
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy
| | - Maria Carla Gerra
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy
| | - Enrico Baruffini
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy
| | - Cristina Dallabona
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy
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21
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Yang J, Chen P, Cao Y, Liu S, Wang W, Li L, Li J, Jiang Z, Ma Y, Chen S, Zheng S, Qi X, Jiang H. Chemical inhibition of mitochondrial fission via targeting the DRP1-receptor interaction. Cell Chem Biol 2023; 30:278-294.e11. [PMID: 36827981 DOI: 10.1016/j.chembiol.2023.02.002] [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: 05/19/2022] [Revised: 09/14/2022] [Accepted: 02/03/2023] [Indexed: 02/25/2023]
Abstract
Mitochondrial fission is critical for mitochondrial dynamics and homeostasis. The dynamin superfamily GTPase DRP1 is recruited by three functionally redundant receptors, MFF, MiD49, and MiD51, to mitochondria to drive fission. Here, we exploit high-content live-cell imaging to screen for mitochondrial fission inhibitors and have developed a covalent compound, mitochondrial division inhibitor (MIDI). MIDI treatment potently blocks mitochondrial fragmentation induced by mitochondrial toxins and restores mitochondrial morphology in fusion-defective cells carrying pathogenic mitofusin and OPA1 mutations. Mechanistically, MIDI does not affect DRP1 tetramerization nor DRP1 GTPase activity but does block DRP1 recruitment to mitochondria. Subsequent biochemical and cellular characterizations reveal an unexpected mechanism that MIDI targets DRP1 interaction with multiple receptors via covalent interaction with DRP1-C367. Taken together, beyond developing a potent mitochondrial fission inhibitor that profoundly impacts mitochondrial morphogenesis, our study establishes proof of concept for developing protein-protein interaction inhibitors targeting DRP1.
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Affiliation(s)
- Jun Yang
- School of Life Sciences, Tsinghua University, Beijing 100084, China; National Institute of Biological Sciences, Beijing 102206, China
| | - Peihao Chen
- National Institute of Biological Sciences, Beijing 102206, China; School of Life Sciences, Peking University, Beijing, China
| | - Yu Cao
- National Institute of Biological Sciences, Beijing 102206, China; College of Life Sciences, Beijing Normal University, Beijing, China
| | - Shanshan Liu
- National Institute of Biological Sciences, Beijing 102206, China
| | - Wei Wang
- National Institute of Biological Sciences, Beijing 102206, China; School of Life Sciences, Peking University, Beijing, China
| | - Lin Li
- National Institute of Biological Sciences, Beijing 102206, China
| | - Jiaojiao Li
- National Institute of Biological Sciences, Beijing 102206, China
| | - Zhaodi Jiang
- National Institute of Biological Sciences, Beijing 102206, China; Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 102206, China
| | - Yan Ma
- National Institute of Biological Sciences, Beijing 102206, China; Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 102206, China
| | - She Chen
- National Institute of Biological Sciences, Beijing 102206, China; Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 102206, China
| | - Sanduo Zheng
- National Institute of Biological Sciences, Beijing 102206, China; Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 102206, China
| | - Xiangbing Qi
- National Institute of Biological Sciences, Beijing 102206, China; Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 102206, China.
| | - Hui Jiang
- School of Life Sciences, Tsinghua University, Beijing 100084, China; National Institute of Biological Sciences, Beijing 102206, China; Beijing Key Laboratory of Cell Biology for Animal Aging, Beijing 102206, China; Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 102206, China.
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22
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Reduced OPA1, Mitochondrial Fragmentation and Increased Susceptibility to Apoptosis in Granular Corneal Dystrophy Type 2 Corneal Fibroblasts. Genes (Basel) 2023; 14:genes14030566. [PMID: 36980838 PMCID: PMC10048436 DOI: 10.3390/genes14030566] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 02/20/2023] [Accepted: 02/22/2023] [Indexed: 03/03/2023] Open
Abstract
The progressive degeneration of granular corneal dystrophy type 2 (GCD2) corneal fibroblasts is associated with altered mitochondrial function, but the underlying mechanisms are incompletely understood. We investigated whether an imbalance of mitochondrial dynamics contributes to mitochondrial dysfunction of GCD2 corneal fibroblasts. Transmission electron microscopy revealed several small, structurally abnormal mitochondria with altered cristae morphology in GCD2 corneal fibroblasts. Confocal microscopy showed enhanced mitochondrial fission and fragmented mitochondrial tubular networks. Western blotting revealed higher levels of MFN1, MFN2, and pDRP1 and decreased levels of OPA1 and FIS1 in GCD2. OPA1 reduction by short hairpin RNA (shRNA) resulted in fragmented mitochondrial tubular networks and increased susceptibility to mitochondrial stress-induced apoptosis. A decrease in the mitochondrial biogenesis-related transcription factors NRF1 and PGC1α was observed, while there was an increase in the mitochondrial membrane proteins TOM20 and TIM23. Additionally, reduced levels of mitochondrial DNA (mtDNA) were exhibited in GCD2 corneal fibroblasts. These observations suggest that altered mitochondrial fission/fusion and biogenesis are the critical molecular mechanisms that cause mitochondrial dysfunction contributing to the degeneration of GCD2 corneal fibroblasts.
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23
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Saidia AR, Ruel J, Bahloul A, Chaix B, Venail F, Wang J. Current Advances in Gene Therapies of Genetic Auditory Neuropathy Spectrum Disorder. J Clin Med 2023; 12:jcm12030738. [PMID: 36769387 PMCID: PMC9918155 DOI: 10.3390/jcm12030738] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 01/11/2023] [Accepted: 01/13/2023] [Indexed: 01/18/2023] Open
Abstract
Auditory neuropathy spectrum disorder (ANSD) refers to a range of hearing impairments characterized by an impaired transmission of sound from the cochlea to the brain. This defect can be due to a lesion or defect in the inner hair cell (IHC), IHC ribbon synapse (e.g., pre-synaptic release of glutamate), postsynaptic terminals of the spiral ganglion neurons, or demyelination and axonal loss within the auditory nerve. To date, the only clinical treatment options for ANSD are hearing aids and cochlear implantation. However, despite the advances in hearing-aid and cochlear-implant technologies, the quality of perceived sound still cannot match that of the normal ear. Recent advanced genetic diagnostics and clinical audiology made it possible to identify the precise site of a lesion and to characterize the specific disease mechanisms of ANSD, thus bringing renewed hope to the treatment or prevention of auditory neurodegeneration. Moreover, genetic routes involving the replacement or corrective editing of mutant sequences or defected genes to repair damaged cells for the future restoration of hearing in deaf people are showing promise. In this review, we provide an update on recent discoveries in the molecular pathophysiology of genetic lesions, auditory synaptopathy and neuropathy, and gene-therapy research towards hearing restoration in rodent models and in clinical trials.
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Affiliation(s)
- Anissa Rym Saidia
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, 34295 Montpellier, France
| | - Jérôme Ruel
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, 34295 Montpellier, France
- Cognitive Neuroscience Laboratory, Aix-Marseille University, CNRS, UMR 7291, 13331 Marseille, France
| | - Amel Bahloul
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, 34295 Montpellier, France
| | - Benjamin Chaix
- Department of ENT and Head and Neck Surgery, University Hospital of Montpellier, 34295 Montpellier, France
| | - Frédéric Venail
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, 34295 Montpellier, France
- Department of ENT and Head and Neck Surgery, University Hospital of Montpellier, 34295 Montpellier, France
| | - Jing Wang
- Institute for Neurosciences of Montpellier (INM), University Montpellier, INSERM, 34295 Montpellier, France
- Department of ENT and Head and Neck Surgery, University Hospital of Montpellier, 34295 Montpellier, France
- Correspondence: ; Tel.: +33-499-63-60-48
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24
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Takeda K, Takemasa T, Fujita R. High Throughput Screening of Mitochondrial Bioenergetics in Myoblasts and Differentiated Myotubes. Methods Mol Biol 2023; 2640:89-98. [PMID: 36995589 DOI: 10.1007/978-1-0716-3036-5_7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
Skeletal muscles contain stem cells called satellite cells, which are essential for muscle regeneration. The population of satellite cells declines with aging and the incidence of pathological conditions such as muscular dystrophy. There is increasing evidence that metabolic switches and mitochondrial function are critical regulators of cell fate decision (quiescence, activation, differentiation, and self-renewal) during myogenesis. Thus, monitoring and identifying the metabolic profile in live cells using the Seahorse XF Bioanalyzer could provide new insights on the molecular mechanisms governing stem cell dynamics during regeneration and tissue maintenance. Here we described a method to assess mitochondrial respiration (oxygen consumption rate) and glycolysis (ECAR) in primary murine satellite cells, multinucleated myotubes, and C2C12 myoblasts.
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Affiliation(s)
- Kohei Takeda
- Faculty of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan
- School of Political Science and Economics, Meiji University, Tokyo, Japan
| | - Tohru Takemasa
- Faculty of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan
| | - Ryo Fujita
- Division of Regenerative Medicine, Transborder Medical Research Center (TMRC), University of Tsukuba, Ibaraki, Japan.
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25
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Guo Z, Wang Z, Gao Z, Feng T, Gao Y, Yin Z, Tian Z, Liu Y, Mao X, Xiang C. The status and trends of mitochondrial dynamics research: A global bibliometric and visualized analysis. J Bioenerg Biomembr 2023; 55:43-57. [PMID: 36807837 PMCID: PMC9942064 DOI: 10.1007/s10863-023-09959-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 02/06/2023] [Indexed: 02/23/2023]
Abstract
BACKGROUND Mitochondria are remarkably dynamic organelles encapsulated by bilayer membranes. The dynamic properties of mitochondria are critical for energy production. AIMS The aim of our study is to investigate the global status and trends of mitochondrial dynamics research and predict popular topics and directions in the field. METHODS Publications related to the studies of mitochondrial dynamics from 2002 to 2021 were retrieved from Web of Science database. A total of 4,576 publications were included. Bibliometric analysis was conducted by visualization of similarities viewer and GraphPadPrism 5 software. RESULTS There is an increasing trend of mitochondrial dynamics research during the last 20 years. The cumulative number of publications about mitochondrial dynamics research followed the logistic growth model [Formula: see text]. The USA made the highest contributions to the global research. The journal Biochimica et Biophysica Acta (BBA)-Molecular Cell Research had the largest publication numbers. Case Western Reserve University is the most contributive institution. The main research orientation and funding agency were cell biology and HHS. All keywords related studies could be divided into three clusters: "Related disease research", "Mechanism research" and "Cell metabolism research". CONCLUSIONS Attention should be drawn to the latest popular research and more efforts will be put into mechanistic research, which may inspire new clinical treatments for the associated diseases.
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Affiliation(s)
- Zijian Guo
- Department of Orthopedic, The Second Hospital of Shanxi Medical University, Taiyuan, China
| | - Zehua Wang
- Department of Orthopedic, The Second Hospital of Shanxi Medical University, Taiyuan, China
| | - Zhenzhong Gao
- Department of Orthopedic, The Second Hospital of Shanxi Medical University, Taiyuan, China
| | - Tengda Feng
- Department of Orthopedic, The Second Hospital of Shanxi Medical University, Taiyuan, China
| | - Yingjie Gao
- Department of Orthopedic, The Second Hospital of Shanxi Medical University, Taiyuan, China
| | - Zhiwen Yin
- Department of Orthopedic, The Second Hospital of Shanxi Medical University, Taiyuan, China
| | - Zui Tian
- Department of Orthopedic, The Second Hospital of Shanxi Medical University, Taiyuan, China
| | - Yang Liu
- Department of Orthopedic, The Second Hospital of Shanxi Medical University, Taiyuan, China
| | - Xingjia Mao
- Department of Basic Medicine Sciences, and Department of Orthopaedics of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, 310058 China
| | - Chuan Xiang
- Department of Orthopedic, The Second Hospital of Shanxi Medical University, Taiyuan, China.
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26
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Ng YS, McFarland R. Mitochondrial encephalomyopathy. HANDBOOK OF CLINICAL NEUROLOGY 2023; 195:563-585. [PMID: 37562887 DOI: 10.1016/b978-0-323-98818-6.00025-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
Mitochondrial dysfunction, especially perturbation of oxidative phosphorylation and adenosine triphosphate (ATP) generation, disrupts cellular homeostasis and is a surprisingly frequent cause of central and peripheral nervous system pathology. Mitochondrial disease is an umbrella term that encompasses a host of clinical syndromes and features caused by in excess of 300 different genetic defects affecting the mitochondrial and nuclear genomes. Patients with mitochondrial disease can present at any age, ranging from neonatal onset to late adult life, with variable organ involvement and neurological manifestations including neurodevelopmental delay, seizures, stroke-like episodes, movement disorders, optic neuropathy, myopathy, and neuropathy. Until relatively recently, analysis of skeletal muscle biopsy was the focus of diagnostic algorithms, but step-changes in the scope and availability of next-generation sequencing technology and multiomics analysis have revolutionized mitochondrial disease diagnosis. Currently, there is no specific therapy for most types of mitochondrial disease, although clinical trials research in the field is gathering momentum. In that context, active management of epilepsy, stroke-like episodes, dystonia, brainstem dysfunction, and Parkinsonism are all the more important in improving patient quality of life and reducing mortality.
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Affiliation(s)
- Yi Shiau Ng
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, United Kingdom.
| | - Robert McFarland
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
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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.
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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
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28
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Shen X, Sun P, Zhang H, Yang H. Mitochondrial quality control in the brain: The physiological and pathological roles. Front Neurosci 2022; 16:1075141. [PMID: 36578825 PMCID: PMC9791200 DOI: 10.3389/fnins.2022.1075141] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 11/24/2022] [Indexed: 12/14/2022] Open
Abstract
The human brain has high energetic expenses and consumes over 20% of total oxygen metabolism. Abnormal brain energy homeostasis leads to various brain diseases. Among multiple factors that contribute to these diseases, mitochondrial dysfunction is one of the most common causes. Maintenance of mitochondrial integrity and functionality is of pivotal importance to brain energy generation. Mitochondrial quality control (MQC), employing the coordination of multiple mechanisms, is evolved to overcome many mitochondrial defects. Thus, not surprisingly, aberrant mitochondrial quality control results in a wide range of brain disorders. Targeting MQC to preserve and restore mitochondrial function has emerged as a promising therapeutic strategy for the prevention and treatment of brain diseases. Here, we set out to summarize the current understanding of mitochondrial quality control in brain homeostasis. We also evaluate potential pharmaceutically and clinically relevant targets in MQC-associated brain disorders.
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Roesch S, O'Sullivan A, Zimmermann G, Mair A, Lipuš C, Mayr JA, Wortmann SB, Rasp G. Mitochondrial Disease and Hearing Loss in Children: A Systematic Review. Laryngoscope 2022; 132:2459-2472. [PMID: 35188226 PMCID: PMC9790539 DOI: 10.1002/lary.30067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 02/01/2022] [Accepted: 02/04/2022] [Indexed: 12/30/2022]
Abstract
OBJECTIVES Hearing loss is a clinical symptom, frequently mentioned in the context of mitochondrial disease. With no cure available for mitochondrial disease, supportive treatment of clinical symptoms like hearing loss is of the utmost importance. The aim of this study was to summarize current knowledge on hearing loss in genetically proven mitochondrial disease in children and deduce possible and necessary consequences in patient care. METHODS Systematic literature review, including Medline, Embase, and Cochrane library. Review protocol was established and registered prior to conduction (International prospective register of systematic reviews-PROSPERO: CRD42020165356). Conduction of this review was done in accordance with MOOSE criteria. RESULTS A total of 23 articles, meeting predefined criteria and providing sufficient information on 75 individuals with childhood onset hearing loss was included for analysis. Both cochlear and retro-cochlear origin of hearing loss can be identified among different types of mitochondrial disease. Analysis was hindered by inhomogeneous reporting and methodical limitations. CONCLUSION Overall, the findings do not allow for a general statement on hearing loss in children with mitochondrial disease. Retro-cochlear hearing loss seems to be found more often than expected. A common feature appears to be progression of hearing loss over time. However, hearing loss in these patients shows manifold characteristics. Therefore, awareness of mitochondrial disease as a possible causative background is important for otolaryngologists. Future attempts rely on standardized reporting and long-term follow-up. LEVEL OF EVIDENCE NA Laryngoscope, 132:2459-2472, 2022.
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Affiliation(s)
- Sebastian Roesch
- Department of Otorhinolaryngology, Head and Neck SurgeryParacelsus Medical UniversitySalzburgAustria
| | - Anna O'Sullivan
- Department of Otorhinolaryngology, Head and Neck SurgeryParacelsus Medical UniversitySalzburgAustria,Insitute of PathologyParacelsus Medical UniversitySalzburgAustria
| | - Georg Zimmermann
- Team Biostatistics and Big Medical Data, IDA Lab SalzburgParacelsus Medical UniversitySalzburgAustria,Department of Research and InnovationParacelsus Medical UniversitySalzburgAustria
| | - Alois Mair
- Department of Otorhinolaryngology, Head and Neck SurgeryParacelsus Medical UniversitySalzburgAustria
| | - Cvetka Lipuš
- PMU University LibraryParacelsus Medical UniversitySalzburgAustria
| | - Johannes A. Mayr
- University Children's HospitalParacelsus Medical UniversitySalzburgAustria
| | - Saskia B. Wortmann
- University Children's HospitalParacelsus Medical UniversitySalzburgAustria,Amalia Children's Hospital, RadboudumcNijmegenThe Netherlands
| | - Gerd Rasp
- Department of Otorhinolaryngology, Head and Neck SurgeryParacelsus Medical UniversitySalzburgAustria
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Sladen PE, Jovanovic K, Guarascio R, Ottaviani D, Salsbury G, Novoselova T, Chapple JP, Yu-Wai-Man P, Cheetham ME. Modelling autosomal dominant optic atrophy associated with OPA1 variants in iPSC-derived retinal ganglion cells. Hum Mol Genet 2022; 31:3478-3493. [PMID: 35652445 PMCID: PMC9558835 DOI: 10.1093/hmg/ddac128] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 05/11/2022] [Accepted: 05/26/2022] [Indexed: 11/14/2022] Open
Abstract
Autosomal dominant optic atrophy (DOA) is the most common inherited optic neuropathy, characterized by the preferential loss of retinal ganglion cells (RGCs), resulting in optic nerve degeneration and progressive bilateral central vision loss. More than 60% of genetically confirmed patients with DOA carry variants in the nuclear OPA1 gene, which encodes for a ubiquitously expressed, mitochondrial GTPase protein. OPA1 has diverse functions within the mitochondrial network, facilitating inner membrane fusion and cristae modelling, regulating mitochondrial DNA maintenance and coordinating mitochondrial bioenergetics. There are currently no licensed disease-modifying therapies for DOA and the disease mechanisms driving RGC degeneration are poorly understood. Here, we describe the generation of isogenic, heterozygous OPA1 null induced pluripotent stem cell (iPSC) (OPA1+/-) through clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 gene editing of a control cell line, in conjunction with the generation of DOA patient-derived iPSC carrying OPA1 variants, namely, the c.2708_2711delTTAG variant (DOA iPSC), and previously reported missense variant iPSC line (c.1334G>A, DOA plus [DOA]+ iPSC) and CRISPR/Cas9 corrected controls. A two-dimensional (2D) differentiation protocol was used to study the effect of OPA1 variants on iPSC-RGC differentiation and mitochondrial function. OPA1+/-, DOA and DOA+ iPSC showed no differentiation deficit compared to control iPSC lines, exhibiting comparable expression of all relevant markers at each stage of differentiation. OPA1+/- and OPA1 variant iPSC-RGCs exhibited impaired mitochondrial homeostasis, with reduced bioenergetic output and compromised mitochondrial DNA maintenance. These data highlight mitochondrial deficits associated with OPA1 dysfunction in human iPSC-RGCs, and establish a platform to study disease mechanisms that contribute to RGC loss in DOA, as well as potential therapeutic interventions.
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Affiliation(s)
- Paul E Sladen
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | | | | | - Daniele Ottaviani
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
- Department of Biology, University of Padua, and Veneto Institute of Molecular Medicine, Padua 35129, Italy
| | - Grace Salsbury
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | - Tatiana Novoselova
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | - J Paul Chapple
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | - Patrick Yu-Wai-Man
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK
- Cambridge Eye Unit, Addenbrooke’s Hospital, Cambridge University Hospital, Cambridge CB2 0QQ, UK
- Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0PY, UK
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Ischemic Preconditioning and Postconditioning Protect the Heart by Preserving the Mitochondrial Network. BIOMED RESEARCH INTERNATIONAL 2022; 2022:6889278. [PMID: 36203484 PMCID: PMC9532115 DOI: 10.1155/2022/6889278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 09/06/2022] [Indexed: 12/02/2022]
Abstract
Background Mitochondria fuse to form elongated networks which are more tolerable to stress and injury. Ischemic pre- and postconditioning (IPC and IPost, respectively) are established cardioprotective strategies in the preclinical setting. Whether IPC and IPost modulates mitochondrial morphology is unknown. We hypothesize that the protective effects of IPC and IPost may be conferred via preservation of mitochondrial network. Methods IPC and IPost were applied to the H9c2 rat myoblast cells, isolated adult primary murine cardiomyocytes, and the Langendorff-isolated perfused rat hearts. The effects of IPC and IPost on cardiac cell death following ischemia-reperfusion injury (IRI), mitochondrial morphology, and gene expression of mitochondrial-shaping proteins were investigated. Results IPC and IPost successfully reduced cardiac cell death and myocardial infarct size. IPC and IPost maintained the mitochondrial network in both H9c2 and isolated adult primary murine cardiomyocytes. 2D-length measurement of the 3 mitochondrial subpopulations showed that IPC and IPost significantly increased the length of interfibrillar mitochondria (IFM). Gene expression of the pro-fusion protein, Mfn1, was significantly increased by IPC, while the pro-fission protein, Drp1, was significantly reduced by IPost in the H9c2 cells. In the primary cardiomyocytes, gene expression of both Mfn1 and Mfn2 were significantly upregulated by IPC and IPost, while Drp1 was significantly downregulated by IPost. In the Langendorff-isolated perfused heart, gene expression of Drp1 was significantly downregulated by both IPC and IPost. Conclusion IPC and IPost-mediated upregulation of pro-fusion proteins (Mfn1 and Mfn2) and downregulation of pro-fission (Drp1) promote maintenance of the interconnected mitochondrial network, ultimately conferring cardioprotection against IRI.
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Akbari M, Nilsen HL, Montaldo NP. Dynamic features of human mitochondrial DNA maintenance and transcription. Front Cell Dev Biol 2022; 10:984245. [PMID: 36158192 PMCID: PMC9491825 DOI: 10.3389/fcell.2022.984245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 08/02/2022] [Indexed: 12/03/2022] Open
Abstract
Mitochondria are the primary sites for cellular energy production and are required for many essential cellular processes. Mitochondrial DNA (mtDNA) is a 16.6 kb circular DNA molecule that encodes only 13 gene products of the approximately 90 different proteins of the respiratory chain complexes and an estimated 1,200 mitochondrial proteins. MtDNA is, however, crucial for organismal development, normal function, and survival. MtDNA maintenance requires mitochondrially targeted nuclear DNA repair enzymes, a mtDNA replisome that is unique to mitochondria, and systems that control mitochondrial morphology and quality control. Here, we provide an overview of the current literature on mtDNA repair and transcription machineries and discuss how dynamic functional interactions between the components of these systems regulate mtDNA maintenance and transcription. A profound understanding of the molecular mechanisms that control mtDNA maintenance and transcription is important as loss of mtDNA integrity is implicated in normal process of aging, inflammation, and the etiology and pathogenesis of a number of diseases.
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Affiliation(s)
- Mansour Akbari
- Department of Medical Biology, Faculty of Health Sciences, UiT-The Arctic University of Norway, Tromsø, Norway
| | - Hilde Loge Nilsen
- Department of Clinical Molecular Biology, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
- Unit for precision medicine, Akershus University Hospital, Nordbyhagen, Norway
- Department of Microbiology, Oslo University Hospital, Oslo, Norway
| | - Nicola Pietro Montaldo
- Department of Clinical Molecular Biology, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
- *Correspondence: Nicola Pietro Montaldo,
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Almannai M, El-Hattab AW, Azamian MS, Ali M, Scaglia F. Mitochondrial DNA maintenance defects: potential therapeutic strategies. Mol Genet Metab 2022; 137:40-48. [PMID: 35914366 PMCID: PMC10401187 DOI: 10.1016/j.ymgme.2022.07.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 07/03/2022] [Accepted: 07/03/2022] [Indexed: 10/17/2022]
Abstract
Mitochondrial DNA (mtDNA) replication depends on the mitochondrial import of hundreds of nuclear encoded proteins that control the mitochondrial genome maintenance and integrity. Defects in these processes result in an expanding group of disorders called mtDNA maintenance defects that are characterized by mtDNA depletion and/or multiple mtDNA deletions with variable phenotypic manifestations. As it applies for mitochondrial disorders in general, current treatment options for mtDNA maintenance defects are limited. Lately, with the development of model organisms, improved understanding of the pathophysiology of these disorders, and a better knowledge of their natural history, the number of preclinical studies and existing and planned clinical trials has been increasing. In this review, we discuss recent preclinical studies and current and future clinical trials concerning potential therapeutic options for the different mtDNA maintenance defects.
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Affiliation(s)
- Mohammed Almannai
- Genetics and Precision Medicine Department (GPM), King Abdullah Specialized Children's Hospital (KASCH), King Abdulaziz Medical City, Ministry of National Guard Health Affairs (MNG-HA), Riyadh, Saudi Arabia
| | - Ayman W El-Hattab
- Department of Clinical Sciences, College of Medicine, University of Sharjah, Sharjah, United Arab Emirates
| | - Mahshid S Azamian
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - May Ali
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Fernando Scaglia
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA; Texas Children's Hospital, Houston, TX, USA; Joint BCM-CUHK Center of Medical Genetics, Prince of Wales Hospital, Shatin, Hong Kong.
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Han J, Li Y, You Y, Fan K, Lei B. Autosomal dominant optic atrophy caused by six novel pathogenic OPA1 variants and genotype-phenotype correlation analysis. BMC Ophthalmol 2022; 22:322. [PMID: 35883160 PMCID: PMC9327245 DOI: 10.1186/s12886-022-02546-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Accepted: 07/20/2022] [Indexed: 11/10/2022] Open
Abstract
PURPOSE To describe the genetic and clinical features of nineteen patients from eleven unrelated Chinese pedigrees with OPA1-related autosomal dominant optic atrophy (ADOA) and define the phenotype-genotype correlations. METHODS Detailed ophthalmic examinations were performed. Targeted next-generation sequencing (NGS) was conducted in the eleven probands using a custom designed panel PS400. Sanger sequencing and cosegregation were used to verify the identified variants. The pathogenicity of gene variants was evaluated according to American College of Medical Genetics and Genomics (ACMG) guidelines. RESULTS Nineteen patients from the eleven unrelated Chinese ADOA pedigrees had impaired vision and optic disc pallor. Optical coherence tomography showed significant thinning of the retinal nerve fiber layer. The visual field showed varying degrees of central or paracentral scotoma. The onset of symptoms occurred between 3 and 24 years of age (median age 6 years). Eleven variants in OPA1 were identified in the cohort, and nine novel variants were identified. Among the novel variants, two splicing variants c.984 + 1_984 + 2delGT, c.1194 + 2 T > C, two stop-gain variants c.1937C > G, c.2830G > T, and one frameshift variant c.2787_2794del8, were determined to be pathogenic based on ACMG. A novel splicing variant c.1316-10 T > G was determined to be likely pathogenic. In addition, a novel missense c.1283A > C (p.N428T) and two novel splicing variants c.2496G > A and c.1065 + 5G > C were of uncertain significance. CONCLUSIONS Six novel pathogenic variants were identified. The findings will facilitate genetic counselling by expanding the pathogenic mutation spectrum of OPA1.
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Affiliation(s)
- Jinfeng Han
- Department of Ophthalmology, Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Zhengzhou University, Zheng-zhou, 450003, China.,Academy of Medical Sciences, Zhengzhou University, Zhengzhou, 450000, China
| | - Ya Li
- Department of Ophthalmology, Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Zhengzhou University, Zheng-zhou, 450003, China.,Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital, 7 Weiwu Road, Zhengzhou, 450003, Henan, China
| | - Ya You
- Department of Ophthalmology, Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Zhengzhou University, Zheng-zhou, 450003, China.,Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital, 7 Weiwu Road, Zhengzhou, 450003, Henan, China
| | - Ke Fan
- Department of Ophthalmology, Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Zhengzhou University, Zheng-zhou, 450003, China.,Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital, 7 Weiwu Road, Zhengzhou, 450003, Henan, China
| | - Bo Lei
- Department of Ophthalmology, Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Zhengzhou University, Zheng-zhou, 450003, China. .,Academy of Medical Sciences, Zhengzhou University, Zhengzhou, 450000, China. .,Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital, 7 Weiwu Road, Zhengzhou, 450003, Henan, China.
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35
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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.
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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
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Harvey JP, Yu-Wai-Man P, Cheetham ME. Characterisation of a novel OPA1 splice variant resulting in cryptic splice site activation and mitochondrial dysfunction. Eur J Hum Genet 2022; 30:848-855. [PMID: 35534703 PMCID: PMC9259687 DOI: 10.1038/s41431-022-01102-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 04/01/2022] [Accepted: 04/12/2022] [Indexed: 12/13/2022] Open
Abstract
Autosomal dominant optic atrophy (DOA) is an inherited optic neuropathy that results in progressive, bilateral visual acuity loss and field defects. OPA1 is the causative gene in around 60% of cases of DOA. The majority of patients have a pure ocular phenotype, but 20% have extra-ocular features (DOA +). We report on a patient with DOA + manifesting as bilateral optic atrophy, spastic paraparesis, urinary incontinence and white matter changes in the central nervous system associated with a novel heterozygous splice variant NM_015560.2(OPA1):c.2356-1 G > T. Further characterisation, which was performed using fibroblasts obtained from a skin biopsy, demonstrated that this variant altered mRNA splicing of the OPA1 transcript, specifically a 21 base pair deletion at the start of exon 24, NM_015560.2(OPA1):p.Cys786_Lys792del. The majority of variant transcripts were shown to escape nonsense-mediated decay and modelling of the predicted protein structure suggests that the in-frame 7 amino acid deletion may affect OPA1 oligomerisation. Fibroblasts carrying the c.2356-1 G > T variant demonstrated impaired mitochondrial bioenergetics, membrane potential, increased cell death, and disrupted and fragmented mitochondrial networks in comparison to WT cells. This study suggests that the c.2356-1 G > T OPA1 splice site variant leads to a cryptic splice site activation and may manifest in a dominant-negative manner, which could account for the patient's severe syndromic phenotype.
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Affiliation(s)
- Joshua Paul Harvey
- UCL Institute of Ophthalmology, London, UK.
- Moorfields Eye Hospital NHS Foundation Trust, London, UK.
| | - Patrick Yu-Wai-Man
- UCL Institute of Ophthalmology, London, UK
- Moorfields Eye Hospital NHS Foundation Trust, London, UK
- Cambridge Eye Unit, Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, UK
- Department of Clinical Neurosciences, John van Geest Centre for Brain Repair and MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, UK
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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.
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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
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38
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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.
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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.
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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.
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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
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Shahroor MA, Lasorsa FM, Porcelli V, Dweikat I, Di Noia MA, Gur M, Agostino G, Shaag A, Rinaldi T, Gasparre G, Guerra F, Castegna A, Todisco S, Abu-Libdeh B, Elpeleg O, Palmieri L. PNC2 (SLC25A36) Deficiency Associated With the Hyperinsulinism/Hyperammonemia Syndrome. J Clin Endocrinol Metab 2022; 107:1346-1356. [PMID: 34971397 DOI: 10.1210/clinem/dgab932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Indexed: 11/19/2022]
Abstract
CONTEXT The hyperinsulinism/hyperammonemia (HI/HA) syndrome, the second-most common form of congenital hyperinsulinism, has been associated with dominant mutations in GLUD1, coding for the mitochondrial enzyme glutamate dehydrogenase, that increase enzyme activity by reducing its sensitivity to allosteric inhibition by GTP. OBJECTIVE To identify the underlying genetic etiology in 2 siblings who presented with the biochemical features of HI/HA syndrome but did not carry pathogenic variants in GLUD1, and to determine the functional impact of the newly identified mutation. METHODS The patients were investigated by whole exome sequencing. Yeast complementation studies and biochemical assays on the recombinant mutated protein were performed. The consequences of stable slc25a36 silencing in HeLa cells were also investigated. RESULTS A homozygous splice site variant was identified in solute carrier family 25, member 36 (SLC25A36), encoding the pyrimidine nucleotide carrier 2 (PNC2), a mitochondrial nucleotide carrier that transports pyrimidine as well as guanine nucleotides across the inner mitochondrial membrane. The mutation leads to a 26-aa in-frame deletion in the first repeat domain of the protein, which abolishes transport activity. Furthermore, knockdown of slc25a36 expression in HeLa cells caused a marked reduction in the mitochondrial GTP content, which likely leads to a hyperactivation of glutamate dehydrogenase in our patients. CONCLUSION We report for the first time a mutation in PNC2/SLC25A36 leading to HI/HA and provide functional evidence of the molecular mechanism responsible for this phenotype. Our findings underscore the importance of mitochondrial nucleotide metabolism and expand the role of mitochondrial transporters in insulin secretion.
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Affiliation(s)
- Maher A Shahroor
- Department of Pediatrics and Genetics, Al Makassed Hospital and Al-Quds University, 95908 Jerusalem, Palestine
- Department of Neonatology, Sunnybrook Health Sciences Center, University of Toronto, M4N 3M5 Toronto, Canada
| | - Francesco M Lasorsa
- Laboratory of Biochemistry and Molecular Biology, Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari Aldo Moro, 70125 Bari, Italy
- CNR Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, 70125 Bari, Italy
| | - Vito Porcelli
- Laboratory of Biochemistry and Molecular Biology, Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari Aldo Moro, 70125 Bari, Italy
| | - Imad Dweikat
- Metabolic Unit, An-Najah National University, P467 Nablus, Palestine
| | - Maria Antonietta Di Noia
- Laboratory of Biochemistry and Molecular Biology, Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari Aldo Moro, 70125 Bari, Italy
| | - Michal Gur
- Department of Genetics, Hadassah, Hebrew University Medical Center, 91120 Jerusalem, Israel
| | - Giulia Agostino
- Laboratory of Biochemistry and Molecular Biology, Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari Aldo Moro, 70125 Bari, Italy
| | - Avraham Shaag
- Department of Genetics, Hadassah, Hebrew University Medical Center, 91120 Jerusalem, Israel
| | - Teresa Rinaldi
- Pasteur Institute-Cenci Bolognetti Foundation, Department of Biology and Biotechnology "Charles Darwin", University of Rome La Sapienza, 00185 Rome, Italy
| | - Giuseppe Gasparre
- Department of Medical and Surgical Sciences (DIMEC), Unit of Medical Genetics and Center for Applied Biomedical Research (CRBA), University of Bologna, 40138 Bologna, Italy
| | - Flora Guerra
- Department of Medical and Surgical Sciences (DIMEC), Unit of Medical Genetics and Center for Applied Biomedical Research (CRBA), University of Bologna, 40138 Bologna, Italy
| | - Alessandra Castegna
- Laboratory of Biochemistry and Molecular Biology, Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari Aldo Moro, 70125 Bari, Italy
- CNR Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, 70125 Bari, Italy
| | - Simona Todisco
- Laboratory of Biochemistry and Molecular Biology, Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari Aldo Moro, 70125 Bari, Italy
| | - Bassam Abu-Libdeh
- Department of Pediatrics and Genetics, Al Makassed Hospital and Al-Quds University, 95908 Jerusalem, Palestine
| | - Orly Elpeleg
- Department of Genetics, Hadassah, Hebrew University Medical Center, 91120 Jerusalem, Israel
| | - Luigi Palmieri
- Laboratory of Biochemistry and Molecular Biology, Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari Aldo Moro, 70125 Bari, Italy
- CNR Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, 70125 Bari, Italy
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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.
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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.
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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,
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Lima T, Li TY, Mottis A, Auwerx J. Pleiotropic effects of mitochondria in aging. NATURE AGING 2022; 2:199-213. [PMID: 37118378 DOI: 10.1038/s43587-022-00191-2] [Citation(s) in RCA: 62] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 02/07/2022] [Indexed: 04/30/2023]
Abstract
Aging is typified by a progressive decline in mitochondrial activity and stress resilience. Here, we review how mitochondrial stress pathways have pleiotropic effects on cellular and systemic homeostasis, which can comprise protective or detrimental responses during aging. We describe recent evidence arguing that defects in these conserved adaptive pathways contribute to aging and age-related diseases. Signaling pathways regulating the mitochondrial unfolded protein response, mitochondrial membrane dynamics, and mitophagy are discussed, emphasizing how their failure contributes to heteroplasmy and de-regulation of key metabolites. Our current understanding of how these processes are controlled and interconnected explains how mitochondria can widely impact fundamental aspects of aging.
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Affiliation(s)
- Tanes Lima
- Laboratory of Integrative Systems Physiology, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Terytty Yang Li
- Laboratory of Integrative Systems Physiology, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Adrienne Mottis
- Laboratory of Integrative Systems Physiology, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Johan Auwerx
- Laboratory of Integrative Systems Physiology, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
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Molecular Genetics Overview of Primary Mitochondrial Myopathies. J Clin Med 2022; 11:jcm11030632. [PMID: 35160083 PMCID: PMC8836969 DOI: 10.3390/jcm11030632] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 01/13/2022] [Accepted: 01/20/2022] [Indexed: 12/29/2022] Open
Abstract
Mitochondrial disorders are the most common inherited conditions, characterized by defects in oxidative phosphorylation and caused by mutations in nuclear or mitochondrial genes. Due to its high energy request, skeletal muscle is typically involved. According to the International Workshop of Experts in Mitochondrial Diseases held in Rome in 2016, the term Primary Mitochondrial Myopathy (PMM) should refer to those mitochondrial disorders affecting principally, but not exclusively, the skeletal muscle. The clinical presentation may include general isolated myopathy with muscle weakness, exercise intolerance, chronic ophthalmoplegia/ophthalmoparesis (cPEO) and eyelids ptosis, or multisystem conditions where there is a coexistence with extramuscular signs and symptoms. In recent years, new therapeutic targets have been identified leading to the launch of some promising clinical trials that have mainly focused on treating muscle symptoms and that require populations with defined genotype. Advantages in next-generation sequencing techniques have substantially improved diagnosis. So far, an increasing number of mutations have been identified as responsible for mitochondrial disorders. In this review, we focused on the principal molecular genetic alterations in PMM. Accordingly, we carried out a comprehensive review of the literature and briefly discussed the possible approaches which could guide the clinician to a genetic diagnosis.
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Cartes-Saavedra B, Macuada J, Lagos D, Arancibia D, Andrés ME, Yu-Wai-Man P, Hajnóczky G, Eisner V. OPA1 Modulates Mitochondrial Ca 2+ Uptake Through ER-Mitochondria Coupling. Front Cell Dev Biol 2022; 9:774108. [PMID: 35047497 PMCID: PMC8762365 DOI: 10.3389/fcell.2021.774108] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Accepted: 11/30/2021] [Indexed: 11/16/2022] Open
Abstract
Autosomal Dominant Optic Atrophy (ADOA), a disease that causes blindness and other neurological disorders, is linked to OPA1 mutations. OPA1, dependent on its GTPase and GED domains, governs inner mitochondrial membrane (IMM) fusion and cristae organization, which are central to oxidative metabolism. Mitochondrial dynamics and IMM organization have also been implicated in Ca2+ homeostasis and signaling but the specific involvements of OPA1 in Ca2+ dynamics remain to be established. Here we studied the possible outcomes of OPA1 and its ADOA-linked mutations in Ca2+ homeostasis using rescue and overexpression strategies in Opa1-deficient and wild-type murine embryonic fibroblasts (MEFs), respectively and in human ADOA-derived fibroblasts. MEFs lacking Opa1 required less Ca2+ mobilization from the endoplasmic reticulum (ER) to induce a mitochondrial matrix [Ca2+] rise ([Ca2+]mito). This was associated with closer ER-mitochondria contacts and no significant changes in the mitochondrial calcium uniporter complex. Patient cells carrying OPA1 GTPase or GED domain mutations also exhibited altered Ca2+ homeostasis, and the mutations associated with lower OPA1 levels displayed closer ER-mitochondria gaps. Furthermore, in Opa1 -/- MEF background, we found that acute expression of OPA1 GTPase mutants but no GED mutants, partially restored cytosolic [Ca2+] ([Ca2+]cyto) needed for a prompt [Ca2+]mito rise. Finally, OPA1 mutants' overexpression in WT MEFs disrupted Ca2+ homeostasis, partially recapitulating the observations in ADOA patient cells. Thus, OPA1 modulates functional ER-mitochondria coupling likely through the OPA1 GED domain in Opa1 -/- MEFs. However, the co-existence of WT and mutant forms of OPA1 in patients promotes an imbalance of Ca2+ homeostasis without a domain-specific effect, likely contributing to the overall ADOA progress.
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Affiliation(s)
- Benjamín Cartes-Saavedra
- Departamento Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
- MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, United States
| | - Josefa Macuada
- Departamento Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Daniel Lagos
- Departamento Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Duxan Arancibia
- Departamento Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - María E. Andrés
- Departamento Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Patrick Yu-Wai-Man
- UCL Institute of Ophthalmology, University College London, London, United Kingdom
- Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
- Cambridge Eye Unit, Addenbrooke’s Hospital, Cambridge University Hospitals, Cambridge, United Kingdom
- John van Geest Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - György Hajnóczky
- MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, United States
| | - Verónica Eisner
- Departamento Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
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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.
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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
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Cytosolic Self-DNA—A Potential Source of Chronic Inflammation in Aging. Cells 2021; 10:cells10123544. [PMID: 34944052 PMCID: PMC8700131 DOI: 10.3390/cells10123544] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 11/28/2021] [Accepted: 12/09/2021] [Indexed: 12/13/2022] Open
Abstract
Aging is the consequence of a lifelong accumulation of stochastic damage to tissues and cellular components. Advancing age closely associates with elevated markers of innate immunity and low-grade chronic inflammation, probably reflecting steady increasing incidents of cellular and tissue damage over the life course. The DNA sensing cGAS-STING signaling pathway is activated by misplaced cytosolic self-DNA, which then initiates the innate immune responses. Here, we hypothesize that the stochastic release of various forms of DNA from the nucleus and mitochondria, e.g., because of DNA damage, altered nucleus integrity, and mitochondrial damage, can result in chronic activation of inflammatory responses that characterize the aging process. This cytosolic self-DNA-innate immunity axis may perturb tissue homeostasis and function that characterizes human aging and age-associated pathology. Proper techniques and experimental models are available to investigate this axis to develop therapeutic interventions.
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Sladen PE, Perdigão PR, Salsbury G, Novoselova T, van der Spuy J, Chapple JP, Yu-Wai-Man P, Cheetham ME. CRISPR-Cas9 correction of OPA1 c.1334G>A: p.R445H restores mitochondrial homeostasis in dominant optic atrophy patient-derived iPSCs. MOLECULAR THERAPY. NUCLEIC ACIDS 2021; 26:432-443. [PMID: 34589289 PMCID: PMC8455316 DOI: 10.1016/j.omtn.2021.08.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 08/09/2021] [Indexed: 12/26/2022]
Abstract
Autosomal dominant optic atrophy (DOA) is the most common inherited optic neuropathy in the United Kingdom. DOA has an insidious onset in early childhood, typically presenting with bilateral, central visual loss caused by the preferential loss of retinal ganglion cells. 60%-70% of genetically confirmed DOA cases are associated with variants in OPA1, a ubiquitously expressed GTPase that regulates mitochondrial homeostasis through coordination of inner membrane fusion, maintenance of cristae structure, and regulation of bioenergetic output. Whether genetic correction of OPA1 pathogenic variants can alleviate disease-associated phenotypes remains unknown. Here, we demonstrate generation of patient-derived OPA1 c.1334G>A: p.R445H mutant induced pluripotent stem cells (iPSCs), followed by correction of OPA1 through CRISPR-Cas9-guided homology-directed repair (HDR) and evaluate the effect of OPA1 correction on mitochondrial homeostasis. CRISPR-Cas9 gene editing demonstrated an efficient method of OPA1 correction, with successful gene correction in 57% of isolated iPSCs. Correction of OPA1 restored mitochondrial homeostasis, re-establishing the mitochondrial network and basal respiration and ATP production levels. In addition, correction of OPA1 re-established the levels of wild-type (WT) mitochondrial DNA (mtDNA) and reduced susceptibility to apoptotic stimuli. These data demonstrate that nuclear gene correction can restore mitochondrial homeostasis and improve mtDNA integrity in DOA patient-derived cells carrying an OPA1 variant.
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Affiliation(s)
- Paul E. Sladen
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | | | - Grace Salsbury
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | - Tatiana Novoselova
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | | | - J. Paul Chapple
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | - Patrick Yu-Wai-Man
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
- Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK
- Cambridge Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, ED Adrian Building, Robinson Way, Cambridge CB2 0PY, UK
- John van Geest Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0PY, UK
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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.
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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
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50
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Santarelli R, Scimemi P, La Morgia C, Cama E, del Castillo I, Carelli V. Electrocochleography in Auditory Neuropathy Related to Mutations in the OTOF or OPA1 Gene. Audiol Res 2021; 11:639-652. [PMID: 34940017 PMCID: PMC8698970 DOI: 10.3390/audiolres11040059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 11/18/2021] [Accepted: 11/19/2021] [Indexed: 11/16/2022] Open
Abstract
Auditory Neuropathy (AN) is characterized by disruption of temporal coding of acoustic signals in auditory nerve fibers resulting in alterations of auditory perceptions. Mutations in several genes have been associated to the most forms of AN. Underlying mechanisms include both pre-synaptic and post-synaptic damage involving inner hair cell (IHC) depolarization, neurotransmitter release, spike initiation in auditory nerve terminals, loss of auditory fibers and impaired conduction. In contrast, outer hair cell (OHC) activities (otoacoustic emissions [OAEs] and cochlear microphonic [CM]) are normal. Disordered synchrony of auditory nerve activity has been suggested as the basis of both the alterations of auditory brainstem responses (ABRs) and reduction of speech perception. We will review how electrocochleography (ECochG) recordings provide detailed information to help objectively define the sites of auditory neural dysfunction and their effect on receptor summating potential (SP) and neural compound action potential (CAP), the latter reflecting disorders of ribbon synapses and auditory nerve fibers.
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Affiliation(s)
- Rosamaria Santarelli
- Department of Neurosciences, University of Padova, Via Belzoni 160, 35121 Padova, Italy; (P.S.); (E.C.)
- Audiology Service, Santi Giovanni e Paolo Hospital, Campo Santi Giovanni e Paolo, Castello 6777, 30122 Venezia, Italy
- Correspondence:
| | - Pietro Scimemi
- Department of Neurosciences, University of Padova, Via Belzoni 160, 35121 Padova, Italy; (P.S.); (E.C.)
- Audiology Service, Santi Giovanni e Paolo Hospital, Campo Santi Giovanni e Paolo, Castello 6777, 30122 Venezia, Italy
| | - Chiara La Morgia
- Department of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna, Via Ugo Foscolo 7, 40123 Bologna, Italy; (C.L.M.); (V.C.)
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Via Altura 3, 40139 Bologna, Italy
| | - Elona Cama
- Department of Neurosciences, University of Padova, Via Belzoni 160, 35121 Padova, Italy; (P.S.); (E.C.)
- Audiology Service, Santi Giovanni e Paolo Hospital, Campo Santi Giovanni e Paolo, Castello 6777, 30122 Venezia, Italy
| | - Ignacio del Castillo
- Servicio de Genética, Hospital Universitario Ramón y Cajal, IRYCIS, 28034 Madrid, Spain;
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), 28034 Madrid, Spain
| | - Valerio Carelli
- Department of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna, Via Ugo Foscolo 7, 40123 Bologna, Italy; (C.L.M.); (V.C.)
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Via Altura 3, 40139 Bologna, Italy
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