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Zanfardino P, Amati A, Doccini S, Cox SN, Tullo A, Longo G, D'Erchia A, Picardi E, Nesti C, Santorelli FM, Petruzzella V. OPA1 mutation affects autophagy and triggers senescence in autosomal dominant optic atrophy plus fibroblasts. Hum Mol Genet 2024; 33:768-786. [PMID: 38280232 DOI: 10.1093/hmg/ddae008] [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: 11/02/2023] [Revised: 01/06/2024] [Indexed: 01/29/2024] Open
Abstract
In several cases of mitochondrial diseases, the underlying genetic and bioenergetic causes of reduced oxidative phosphorylation (OxPhos) in mitochondrial dysfunction are well understood. However, there is still limited knowledge about the specific cellular outcomes and factors involved for each gene and mutation, which contributes to the lack of effective treatments for these disorders. This study focused on fibroblasts from a patient with Autosomal Dominant Optic Atrophy (ADOA) plus syndrome harboring a mutation in the Optic Atrophy 1 (OPA1) gene. By combining functional and transcriptomic approaches, we investigated the mitochondrial function and identified cellular phenotypes associated with the disease. Our findings revealed that fibroblasts with the OPA1 mutation exhibited a disrupted mitochondrial network and function, leading to altered mitochondrial dynamics and reduced autophagic response. Additionally, we observed a premature senescence phenotype in these cells, suggesting a previously unexplored role of the OPA1 gene in inducing senescence in ADOA plus patients. This study provides novel insights into the mechanisms underlying mitochondrial dysfunction in ADOA plus and highlights the potential importance of senescence in disease progression.
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Affiliation(s)
- Paola Zanfardino
- Department of Translational Biomedicine and Neuroscience (DiBraiN), University of study of Bari Aldo Moro, Piazza G. Cesare, 11, 70124 Bari, Italy
| | - Alessandro Amati
- Department of Translational Biomedicine and Neuroscience (DiBraiN), University of study of Bari Aldo Moro, Piazza G. Cesare, 11, 70124 Bari, Italy
| | - Stefano Doccini
- Molecular Medicine for Neurodegenerative and Neuromuscular Diseases Unit, IRCCS Stella Maris Foundation, Viale del Tirreno, 56128 Calambrone, Pisa, Italy
| | - Sharon N Cox
- Department of Biosciences, Biotechnology, and Biopharmaceutics, University of study of Bari Aldo Moro, via Orabona 4, 70125, Bari, Italy
| | - Apollonia Tullo
- Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies (IBIOM), National Research Council, Via G. Amendola 122/O, 70126 Bari, Italy
| | - Giovanna Longo
- Department of Translational Biomedicine and Neuroscience (DiBraiN), University of study of Bari Aldo Moro, Piazza G. Cesare, 11, 70124 Bari, Italy
| | - Annamaria D'Erchia
- Department of Biosciences, Biotechnology, and Biopharmaceutics, University of study of Bari Aldo Moro, via Orabona 4, 70125, Bari, Italy
| | - Ernesto Picardi
- Department of Biosciences, Biotechnology, and Biopharmaceutics, University of study of Bari Aldo Moro, via Orabona 4, 70125, Bari, Italy
| | - Claudia Nesti
- Molecular Medicine for Neurodegenerative and Neuromuscular Diseases Unit, IRCCS Stella Maris Foundation, Viale del Tirreno, 56128 Calambrone, Pisa, Italy
| | - Filippo M Santorelli
- Molecular Medicine for Neurodegenerative and Neuromuscular Diseases Unit, IRCCS Stella Maris Foundation, Viale del Tirreno, 56128 Calambrone, Pisa, Italy
| | - Vittoria Petruzzella
- Department of Translational Biomedicine and Neuroscience (DiBraiN), University of study of Bari Aldo Moro, Piazza G. Cesare, 11, 70124 Bari, Italy
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2
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de Wet S, Theart R, Loos B. Cogs in the autophagic machine-equipped to combat dementia-prone neurodegenerative diseases. Front Mol Neurosci 2023; 16:1225227. [PMID: 37720551 PMCID: PMC10500130 DOI: 10.3389/fnmol.2023.1225227] [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: 05/18/2023] [Accepted: 07/31/2023] [Indexed: 09/19/2023] Open
Abstract
Neurodegenerative diseases are often characterized by hydrophobic inclusion bodies, and it may be the case that the aggregate-prone proteins that comprise these inclusion bodies are in fact the cause of neurotoxicity. Indeed, the appearance of protein aggregates leads to a proteostatic imbalance that causes various interruptions in physiological cellular processes, including lysosomal and mitochondrial dysfunction, as well as break down in calcium homeostasis. Oftentimes the approach to counteract proteotoxicity is taken to merely upregulate autophagy, measured by an increase in autophagosomes, without a deeper assessment of contributors toward effective turnover through autophagy. There are various ways in which autophagy is regulated ranging from the mammalian target of rapamycin (mTOR) to acetylation status of proteins. Healthy mitochondria and the intracellular energetic charge they preserve are key for the acidification status of lysosomes and thus ensuring effective clearance of components through the autophagy pathway. Both mitochondria and lysosomes have been shown to bear functional protein complexes that aid in the regulation of autophagy. Indeed, it may be the case that minimizing the proteins associated with the respective neurodegenerative pathology may be of greater importance than addressing molecularly their resulting inclusion bodies. It is in this context that this review will dissect the autophagy signaling pathway, its control and the manner in which it is molecularly and functionally connected with the mitochondrial and lysosomal system, as well as provide a summary of the role of autophagy dysfunction in driving neurodegenerative disease as a means to better position the potential of rapamycin-mediated bioactivities to control autophagy favorably.
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Affiliation(s)
- Sholto de Wet
- Department of Physiological Sciences, Stellenbosch University, Stellenbosch, South Africa
| | - Rensu Theart
- Department of Electric and Electronic Engineering, Stellenbosch University, Stellenbosch, South Africa
| | - Ben Loos
- Department of Physiological Sciences, Stellenbosch University, Stellenbosch, South Africa
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3
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Chojnacki AK, Navaneetha Krishnan S, Jijon H, Shutt TE, Colarusso P, McKay DM. Tissue imaging reveals disruption of epithelial mitochondrial networks and loss of mitochondria-associated cytochrome-C in inflamed human and murine colon. Mitochondrion 2023; 68:44-59. [PMID: 36356719 DOI: 10.1016/j.mito.2022.10.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Revised: 09/20/2022] [Accepted: 10/23/2022] [Indexed: 11/09/2022]
Abstract
Mitochondrial dysfunction as defined by transcriptomic and proteomic analysis of biopsies or ultra-structure in transmission electron microscopy occurs in inflammatory bowel disease (IBD); however, mitochondrial dynamics in IBD have received minimal attention, with most investigations relying on cell-based in vitro models. We build on these studies by adapting the epithelial cell immunofluorescence workflow to imaging mitochondrial networks in normal and inflamed colonic tissue (i.e., murine di-nitrobenzene sulphonic acid (DNBS)-induced colitis, human ulcerative colitis). Using antibodies directed to TOMM20 (translocase of outer mitochondrial membrane 20) and cytochrome-C, we have translated the cell-based protocol for high-fidelity imaging to examine epithelial mitochondria networks in intact intestine. In epithelia of non-inflamed small or large intestinal tissue, the mitochondrial networks were dense and compact. This pattern was more pronounced in the basal region of the cell compared to that between the nucleus and apical surface facing the gut lumen. In comparison, mitochondrial networks in inflamed tissue displayed substantial loss of TOMM20+ staining. The remaining networks were less dense and fragmented, and contained isolated spherical mitochondrial fragments. The degree of mitochondrial network fragmentation mirrored the severity of inflammation, as assessed by blinded semi-quantitative scoring. As an indication of poor cell 'health' or viability, cytosolic cytochrome-C was observed in enterocytes with highly fragmented mitochondria. Thus, high-resolution and detailed visualization of mitochondrial networks in tissue is a feasible and valuable approach to assess disease, suited to characterizing mitochondrial abnormalities in tissue. We speculate that drugs that maintain a functional remodelling mitochondrial network and limit excess fragmentation could be a valuable addition to current therapies for IBD.
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Affiliation(s)
- Andrew K Chojnacki
- Live Cell Imaging Laboratory, Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Saranya Navaneetha Krishnan
- Gastrointestinal Research Group, Inflammation Research Network, Host-Parasite Interactions Program, Department of Physiology & Pharmacology, Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Humberto Jijon
- Division of Gastroenterology, Gastrointestinal Research Group, Department of Medicine, Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Timothy E Shutt
- Departments of Medical Genetics and Biochemistry & Molecular Biology, Alberta Children's Hospital Research Institute, Hotchkiss Brain Institute, Snyder Institute for Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Pina Colarusso
- Live Cell Imaging Laboratory, Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada; Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
| | - Derek M McKay
- Gastrointestinal Research Group, Inflammation Research Network, Host-Parasite Interactions Program, Department of Physiology & Pharmacology, Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
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4
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Deng R, Wang Y, Bu Y, Wu H. BNIP3 mediates the different adaptive responses of fibroblast-like synovial cells to hypoxia in patients with osteoarthritis and rheumatoid arthritis. Mol Med 2022; 28:64. [PMID: 35690741 PMCID: PMC9188199 DOI: 10.1186/s10020-022-00490-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 05/25/2022] [Indexed: 01/01/2023] Open
Abstract
Background Hypoxia is one of the important characteristics of synovial microenvironment in rheumatoid arthritis (RA), and plays an important role in synovial hyperplasia. In terms of cell survival, fibroblast-like synovial cells (FLSs) are relatively affected by hypoxia. In contrast, fibroblast-like synovial cells from patients with RA (RA-FLSs) are particularly resistant to hypoxia-induced cell death. The purpose of this study was to evaluate whether fibroblast-like synovial cells in patients with osteoarthritis (OA-FLSs) and RA-FLSs have the same adaptation to hypoxia. Methods CCK-8, flow cytometry and BrdU were used to detect the proliferation of OA-FLSs and RA-FLSs under different oxygen concentrations. Apoptosis was detected by AV/PI, TUNEL and Western blot, mitophagy was observed by electron microscope, laser confocal microscope and Western blot, the state of mitochondria was detected by ROS and mitochondrial membrane potential by flow cytometry, BNIP3 and HIF-1α were detected by Western blot and RT-qPCR. The silencing of BNIP3 was achieved by stealth RNA system technology. Results After hypoxia, the survival rate of OA-FLSs decreased, while the proliferation activity of RA-FLSs further increased. Hypoxia induced an increase in apoptosis and inhibition of mitophagy in OA-FLSs, but not in RA-FLSs. Hypoxia led to a more lasting adaptive response. RA-FLSs displayed a more significant increase in the expression of genes transcriptionally regulated by HIF-1α. Interestingly, they showed higher BNIP3 expression than OA-FLSs, and showed stronger mitophagy and proliferation activities. BNIP3 siRNA experiment confirmed the potential role of BNIP3 in the survival of RA-FLSs. Inhibition of BNIP3 resulted in the decrease of cell proliferation, mitophagy and the increase of apoptosis. Conclusion In summary, RA-FLSs maintained intracellular redox balance through mitophagy to promote cell survival under hypoxia. The mitophagy of OA-FLSs was too little to maintain the redox balance of mitochondria, resulting in apoptosis. The difference of mitophagy between OA-FLSs and RA-FLSs under hypoxia is mediated by the level of BNIP3 expression.
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Affiliation(s)
- Ran Deng
- Key Laboratory of Xin'an Medicine, Ministry of Education, Hefei, 230012, China.,Anhui University of Chinese Medicine, Qian Jiang Road 1, Hefei, 230012, China.,Anhui Province Key Laboratory of Research &, Development of Chinese Medicine, Hefei, 230012, China
| | - Yan Wang
- Key Laboratory of Xin'an Medicine, Ministry of Education, Hefei, 230012, China.,Anhui University of Chinese Medicine, Qian Jiang Road 1, Hefei, 230012, China.,Anhui Province Key Laboratory of Research &, Development of Chinese Medicine, Hefei, 230012, China
| | - Yanhong Bu
- Key Laboratory of Xin'an Medicine, Ministry of Education, Hefei, 230012, China.,Anhui University of Chinese Medicine, Qian Jiang Road 1, Hefei, 230012, China.,Anhui Province Key Laboratory of Research &, Development of Chinese Medicine, Hefei, 230012, China
| | - Hong Wu
- Key Laboratory of Xin'an Medicine, Ministry of Education, Hefei, 230012, China. .,Anhui University of Chinese Medicine, Qian Jiang Road 1, Hefei, 230012, China. .,Anhui Province Key Laboratory of Research &, Development of Chinese Medicine, Hefei, 230012, China. .,College of Pharmacy, Anhui University of Chinese Medicine, Hefei, 230012, China.
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5
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Ramachandra Rao S, Fliesler SJ. Monitoring basal autophagy in the retina utilizing CAG-mRFP-EGFP-MAP1LC3B reporter mouse: technical and biological considerations. Autophagy 2021; 18:1187-1201. [PMID: 34674604 PMCID: PMC9196719 DOI: 10.1080/15548627.2021.1969634] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
We describe the utility of a tandem-tagged autophagy reporter mouse model (CAG-RFP-EGFP-MAP1LC3B) in investigating basal macroautophagic/autophagic flux in the neural retina. Western blot, in situ hybridization, immunohistochemistry, and confocal microscopy showed that CAG promoter-driven expression of RFP-EGFP-MAP1LC3B increased “cytosolic” RFP-EGFP-LC3B-I levels, whereas RFP-EGFP-LC3B-II decorates true phagosomes. We verified that the electroretinographic (ERG) responses of tandem-tagged LC3B mice were comparable to those of age-matched controls. Optimized microscope settings detected lipofuscin autofluorescence in retinas of abca4−/- mice. The majority of retinal phagosomes in the reporter mice exhibited only RFP (not EGFP) fluorescence, suggesting rapid maturation of phagosomes. Only ~1.5% of the total phagosome population was EGFP-labeled; RFP-labeled (mature) phagosomes colocalized with lysosomal markers LAMP2 and CTSD. In the outer retina, phagosome sizes were as follows (in µm2, ave ± SEM): RPE, 0.309 ± 0.015; photoreceptor inner segment-myoid, 0.544 ± 0.031; and outer nuclear layer, 0.429 ± 0.011. Detection of RPE phagosomes by fluorescence microscopy is challenging, due to the presence of melanin. Increased lipofuscin autofluorescence, such as observed in the abca4−/- mouse model of Stargardt disease, is a strong confounding factor when attempting to study autophagy in the RPE. In addition to RPE and photoreceptor cells, phagosomes were detected in inner retinal cell types, microglia, astrocytes, and endothelial cells. We conclude that the tandem-tagged LC3B mouse model serves as a useful system for studying autophagy in the retina. This utility, however, is dependent upon several technical and biological factors, including microscope settings, transgene expression, choice of fluorophores, and lipofuscin autofluorescence. Abbreviations: ACTB: actin, beta; AIF1: allograft inflammatory factor 1; ATG: autophagy related; CTSD: cathepsin D; DAPI: (4’,6-diamido-2-phenylindole); DIC: differential interference contrast; EGFP: enhanced green fluorescent protein; ELM: external limiting membrane; ERG: electroretinography; GCL: ganglion cell layer; GLUL: glutamine-ammonia ligase (glutamine synthetase); INL: inner nuclear layer; IS-E/M: inner segment – ellipsoid/myoid; ISH: in situ hybridization; LAMP2: lysosomal-associated membrane protein 2; L.I.: laser Intensity; MAP1LC3B: microtubule-associated protein 1 light chain 3 beta; MTOR: mechanistic target of rapamycin kinase; O.C.T.: optimal cutting temperature; OS: outer segment; ONL: outer nuclear layer; PE: phosphatidylethanolamine; RFP: red fluorescent protein; R.O.I.: region of interest; RPE: retinal pigment epithelium
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Affiliation(s)
- Sriganesh Ramachandra Rao
- Departments of Ophthalmology and Biochemistry and Neuroscience Graduate Program, Jacobs School of Medicine and Biomedical Sciences, State University of New York- University at Buffalo, Buffalo, NY, USA.,Research Service, VA Western Ny Healthcare System, Buffalo, NY, USA
| | - Steven J Fliesler
- Departments of Ophthalmology and Biochemistry and Neuroscience Graduate Program, Jacobs School of Medicine and Biomedical Sciences, State University of New York- University at Buffalo, Buffalo, NY, USA.,Research Service, VA Western Ny Healthcare System, Buffalo, NY, USA
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6
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Lenaers G, Neutzner A, Le Dantec Y, Jüschke C, Xiao T, Decembrini S, Swirski S, Kieninger S, Agca C, Kim US, Reynier P, Yu-Wai-Man P, Neidhardt J, Wissinger B. Dominant optic atrophy: Culprit mitochondria in the optic nerve. Prog Retin Eye Res 2021; 83:100935. [PMID: 33340656 DOI: 10.1016/j.preteyeres.2020.100935] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 12/05/2020] [Accepted: 12/09/2020] [Indexed: 12/14/2022]
Abstract
Dominant optic atrophy (DOA) is an inherited mitochondrial disease leading to specific degeneration of retinal ganglion cells (RGCs), thus compromising transmission of visual information from the retina to the brain. Usually, DOA starts during childhood and evolves to poor vision or legal blindness, affecting the central vision, whilst sparing the peripheral visual field. In 20% of cases, DOA presents as syndromic disorder, with secondary symptoms affecting neuronal and muscular functions. Twenty years ago, we demonstrated that heterozygous mutations in OPA1 are the most frequent molecular cause of DOA. Since then, variants in additional genes, whose functions in many instances converge with those of OPA1, have been identified by next generation sequencing. OPA1 encodes a dynamin-related GTPase imported into mitochondria and located to the inner membrane and intermembrane space. The many OPA1 isoforms, resulting from alternative splicing of three exons, form complex homopolymers that structure mitochondrial cristae, and contribute to fusion of the outer membrane, thus shaping the whole mitochondrial network. Moreover, OPA1 is required for oxidative phosphorylation, maintenance of mitochondrial genome, calcium homeostasis and regulation of apoptosis, thus making OPA1 the Swiss army-knife of mitochondria. Understanding DOA pathophysiology requires the understanding of RGC peculiarities with respect to OPA1 functions. Besides the tremendous energy requirements of RGCs to relay visual information from the eye to the brain, these neurons present unique features related to their differential environments in the retina, and to the anatomical transition occurring at the lamina cribrosa, which parallel major adaptations of mitochondrial physiology and shape, in the pre- and post-laminar segments of the optic nerve. Three DOA mouse models, with different Opa1 mutations, have been generated to study intrinsic mechanisms responsible for RGC degeneration, and these have further revealed secondary symptoms related to mitochondrial dysfunctions, mirroring the more severe syndromic phenotypes seen in a subgroup of patients. Metabolomics analyses of cells, mouse organs and patient plasma mutated for OPA1 revealed new unexpected pathophysiological mechanisms related to mitochondrial dysfunction, and biomarkers correlated quantitatively to the severity of the disease. Here, we review and synthesize these data, and propose different approaches for embracing possible therapies to fulfil the unmet clinical needs of this disease, and provide hope to affected DOA patients.
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Affiliation(s)
- Guy Lenaers
- MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, Angers University and Hospital, Angers, France.
| | - Albert Neutzner
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland; Department of Ophthalmology University Hospital Basel, University of Basel, Basel, Switzerland.
| | - Yannick Le Dantec
- MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, Angers University and Hospital, Angers, France
| | - Christoph Jüschke
- Human Genetics, Faculty VI - School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
| | - Ting Xiao
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Center for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Sarah Decembrini
- Department of Biomedicine, University Hospital Basel, University of Basel, Basel, Switzerland; Department of Ophthalmology University Hospital Basel, University of Basel, Basel, Switzerland
| | - Sebastian Swirski
- Human Genetics, Faculty VI - School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
| | - Sinja Kieninger
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Center for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Cavit Agca
- Molecular Biology, Genetics and Bioengineering Program, Sabanci University, Istanbul, Turkey; Nanotechnology Research and Application Center (SUNUM), Sabanci University, Istanbul, Turkey
| | - Ungsoo S Kim
- Kim's Eye Hospital, Seoul, South Korea; Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK; Cambridge Eye Unit, Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, UK; Moorfields Eye Hospital, London, UK
| | - Pascal Reynier
- MitoLab Team, UMR CNRS 6015 - INSERM U1083, Institut MitoVasc, Angers University and Hospital, Angers, France; Department of Biochemistry, University Hospital of Angers, Angers, France
| | - Patrick Yu-Wai-Man
- Cambridge Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK; Cambridge Eye Unit, Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, UK; Moorfields Eye Hospital, London, UK; UCL Institute of Ophthalmology, University College London, London, UK
| | - John Neidhardt
- Human Genetics, Faculty VI - School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany; Research Center Neurosensory Science, University Oldenburg, Oldenburg, Germany.
| | - Bernd Wissinger
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Center for Ophthalmology, University of Tübingen, Tübingen, Germany.
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Del Dotto V, Carelli V. Dominant Optic Atrophy (DOA): Modeling the Kaleidoscopic Roles of OPA1 in Mitochondrial Homeostasis. Front Neurol 2021; 12:681326. [PMID: 34177786 PMCID: PMC8220150 DOI: 10.3389/fneur.2021.681326] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 04/22/2021] [Indexed: 02/05/2023] Open
Abstract
In the year 2000, the discovery of OPA1 mutations as causative for dominant optic atrophy (DOA) was pivotal to rapidly expand the field of mitochondrial dynamics and describe the complex machinery governing this pathway, with a multitude of other genes and encoded proteins involved in neurodegenerative disorders of the optic nerve. OPA1 turned out to be a much more complex protein than initially envisaged, connecting multiple pathways beyond its strict role in mitochondrial fusion, such as sensing of OXPHOS needs and mitochondrial DNA maintenance. As a consequence, an increasing need to investigate OPA1 functions at multiple levels has imposed the development of multiple tools and models that are here reviewed. Translational mitochondrial medicine, with the ultimate objective of translating basic science necessary to understand pathogenic mechanisms into therapeutic strategies, requires disease modeling at multiple levels: from the simplest, like in yeast, to cell models, including the increasing use of reprogrammed stem cells (iPSCs) from patients, to animal models. In the present review, we thoroughly examine and provide the state of the art of all these approaches.
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Affiliation(s)
- Valentina Del Dotto
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | - Valerio Carelli
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy.,Istituto di Ricovero e Cura a Carattere Scientifico Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, Bologna, Italy
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8
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Maresca A, Carelli V. Molecular Mechanisms behind Inherited Neurodegeneration of the Optic Nerve. Biomolecules 2021; 11:496. [PMID: 33806088 PMCID: PMC8064499 DOI: 10.3390/biom11040496] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 03/22/2021] [Accepted: 03/23/2021] [Indexed: 01/01/2023] Open
Abstract
Inherited neurodegeneration of the optic nerve is a paradigm in neurology, as many forms of isolated or syndromic optic atrophy are encountered in clinical practice. The retinal ganglion cells originate the axons that form the optic nerve. They are particularly vulnerable to mitochondrial dysfunction, as they present a peculiar cellular architecture, with axons that are not myelinated for a long intra-retinal segment, thus, very energy dependent. The genetic landscape of causative mutations and genes greatly enlarged in the last decade, pointing to common pathways. These mostly imply mitochondrial dysfunction, which leads to a similar outcome in terms of neurodegeneration. We here critically review these pathways, which include (1) complex I-related oxidative phosphorylation (OXPHOS) dysfunction, (2) mitochondrial dynamics, and (3) endoplasmic reticulum-mitochondrial inter-organellar crosstalk. These major pathogenic mechanisms are in turn interconnected and represent the target for therapeutic strategies. Thus, their deep understanding is the basis to set and test new effective therapies, an urgent unmet need for these patients. New tools are now available to capture all interlinked mechanistic intricacies for the pathogenesis of optic nerve neurodegeneration, casting hope for innovative therapies to be rapidly transferred into the clinic and effectively cure inherited optic neuropathies.
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Affiliation(s)
- Alessandra Maresca
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, 40139 Bologna, Italy;
| | - Valerio Carelli
- IRCCS Istituto delle Scienze Neurologiche di Bologna, Programma di Neurogenetica, 40139 Bologna, Italy;
- Department of Biomedical and Neuromotor Sciences, University of Bologna, 40139 Bologna, Italy
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9
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Tzeng HR, Lee MT, Fan PC, Knutson DE, Lai TH, Sieghart W, Cook J, Chiou LC. α6GABA A Receptor Positive Modulators Alleviate Migraine-like Grimaces in Mice via Compensating GABAergic Deficits in Trigeminal Ganglia. Neurotherapeutics 2021; 18:569-585. [PMID: 33111258 PMCID: PMC8116449 DOI: 10.1007/s13311-020-00951-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/10/2020] [Indexed: 11/29/2022] Open
Abstract
Migraine is caused by hyperactivity of the trigeminovascular system, where trigeminal ganglia (TG) play an important role. This hyperactivity might originate from an underfunctional GABAergic system in TG. To investigate this possibility, we adapted a mouse model of migraine by inducing migraine-like grimaces in male mice via repeated injections of nitroglycerin (NTG, 10 mg/kg, i.p.), once every 2 days, for up to 5 sessions. Migraine-like facial pain scores were measured using the mouse grimace scale. Repeated NTG treatments in mice caused significant increases in migraine-like grimaces that were aborted and prevented by two anti-migraine agents sumatriptan and topiramate, respectively. After 5 sessions of NTG injections, the GABA-synthesizing enzyme, 65-kDa glutamate decarboxylase (GAD65), but not the GABA transporter 1 (GAT1) or the α6 subunit-containing GABAA receptors (α6GABAARs), was downregulated in mouse TG tissues. Taking advantage of the unaffected TG α6GABAAR expression in NTG-treated mice, we demonstrated that an α6GABAAR-selective positive allosteric modulator (PAM), DK-I-56-1, exhibited both abortive and prophylactic effects, comparable to those of sumatriptan and topiramate, respectively, in this migraine-mimicking mouse model. The brain-impermeable furosemide significantly prevented the effects of DK-I-56-1, suggesting its peripheral site of action, likely via preventing α6GABAAR modulation in TG. Results suggest that a decreased GABA synthesis caused by the reduced GAD65 expression in TG contributes to the trigeminovascular activation in this repeated NTG-induced migraine-mimicking model and that the unaltered α6GABAARs in TG are potential targets for migraine treatment. Thus, α6GABAAR-selective PAMs are potential anti-migraine agents for both abortive and preventive therapies.
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Affiliation(s)
- Hung-Ruei Tzeng
- Department of Pharmacology, Graduate Institute of Pharmacology College of Medicine, National Taiwan University, No. 1, Jen-Ai Rd., Section 1, Taipei, 10051, Taiwan
| | - Ming Tatt Lee
- Graduate Institute of Brain and Mind Sciences College of Medicine, National Taiwan University, Taipei, 10051, Taiwan
- Faculty of Pharmaceutical Sciences, UCSI University, 56000, Kuala Lumpur, Malaysia
| | - Pi-Chuan Fan
- Department of Pediatrics, College of Medicine, National Taiwan University, Taipei, 10051, Taiwan
- Department of Pediatrics, National Taiwan University Hospital, Taipei, 10002, Taiwan
| | - Daniel E Knutson
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, WI, 53211, USA
| | - Tzu-Hsuan Lai
- Department of Pediatrics, National Taiwan University Hospital, Taipei, 10002, Taiwan
| | - Werner Sieghart
- Center for Brain Research, Department of Molecular Neurosciences, Medical University Vienna, 1090, Vienna, Austria
| | - James Cook
- Department of Chemistry and Biochemistry, Milwaukee Institute for Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, WI, 53211, USA
| | - Lih-Chu Chiou
- Department of Pharmacology, Graduate Institute of Pharmacology College of Medicine, National Taiwan University, No. 1, Jen-Ai Rd., Section 1, Taipei, 10051, Taiwan.
- Graduate Institute of Brain and Mind Sciences College of Medicine, National Taiwan University, Taipei, 10051, Taiwan.
- Graduate Institute of Acupuncture Science, China Medical University, Taichung, 40402, Taiwan.
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