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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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Kritskaya KA, Fedotova EI, Berezhnov AV. Impaired Mitochondrial Network Morphology and Reactive Oxygen Species Production in Fibroblasts from Parkinson's Disease Patients. Biomedicines 2024; 12:282. [PMID: 38397882 PMCID: PMC10886641 DOI: 10.3390/biomedicines12020282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 01/17/2024] [Accepted: 01/22/2024] [Indexed: 02/25/2024] Open
Abstract
The mitochondrial network (MN) is a dynamic structure undergoing constant remodeling in the cell. It is assumed that perturbations to the MN may be associated with various pathologies, including Parkinson's disease (PD). Using automatic image analysis and super-resolution microscopy, we have assessed the MN parameters in fibroblasts from patients with established hereditary PD mutations (associated with PINK1, LRRK2, and α-synuclein, as well as PINK1 and Parkin proteins simultaneously) under normal conditions and after hydrogen peroxide-induced stress. Fibroblasts with the Pink1/Parkin mutation are most different in morphology to fibroblasts obtained from conditionally healthy donors: the MN is larger, and it contains longer mitochondria and accumulated individual mitochondria. In addition to MN, we evaluated other cellular parameters, such as cytosolic and mitochondrial ROS production and mitochondrial membrane potential. It has been shown that mitochondria of fibroblasts with mutations in genes encoding PINK1, α-synuclein, and Pink/Parkin tend towards hyperpolarization and cytosolic ROS overproduction, while mitochondrial ROS production was higher only in fibroblasts with PINK1 and α-synuclein mutations.
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Affiliation(s)
- Kristina A. Kritskaya
- Institute of Cell Biophysics, Russian Academy of Sciences, Federal Research Center “Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences”, 3 Institutskaya Street, 142290 Pushchino, Russia;
| | | | - Alexey V. Berezhnov
- Institute of Cell Biophysics, Russian Academy of Sciences, Federal Research Center “Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences”, 3 Institutskaya Street, 142290 Pushchino, Russia;
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3
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Fan X, Yang Y, Wu G, Kong Y, Zhang Y, Zha X. Circ-CARD6 inhibits oxidative stress-induced apoptosis and autophagy in ARPE-19 cells via the miR-29b-3p/PRDX6/PI3K/Akt axis. Exp Eye Res 2024; 238:109690. [PMID: 37939831 DOI: 10.1016/j.exer.2023.109690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 09/28/2023] [Accepted: 10/22/2023] [Indexed: 11/10/2023]
Abstract
BACKGROUND Oxidative stress-induced damage and dysfunction of retinal pigment epithelium (RPE) cells are important pathogenetic factors of age-related macular degeneration (AMD) and hereditary retinopathy diseases (HRDs). This study aimed to elucidate the roles and mechanisms of circ-CARD6 and miR-29b-3p in oxidative stress-induced RPE and provide new ideas for the diagnosis and treatment of retinopathy disease (RD). METHODS A model of oxidative stress-induced RPE (ARPE-19) was established, and the level of malondialdehyde (MDA) and concentration of reactive oxygen species (ROS) were detected by a DCFH-DA fluorescent probe and MDA kit. The cell viability was measured by a CCK-8 assay. The expression of PRDX6/PI3K/Akt axis genes and proteins related to apoptosis and autophagy were determined by RT‒qPCR and Western blot analyses. The dual-luciferase reporter system confirmed the targeting relationship between miR-29b-3p and circ-CARD6 and between miR-29b-3p and PRDX6. RESULTS In H2O2-treated ARPE-19 cells, the expression of circ-CARD6 and PRDX6 was decreased, while the expression of miR-29b-3p was increased. The overexpression of circ-CARD6 inhibits oxidative stress-induced increases in ROS, apoptosis and autophagy in ARPE-19 cells. circ-CARD6 targets miR-29b-3p, miR-29b-3p targets PRDX6, and circ-CARD6 regulates PRDX6 via miR-29b-3p. Further studies showed that circ-CARD6 acts as a competitive endogenous RNA of miR-29b-3p to affect the expression of PRDX6, thereby inhibiting autophagy and apoptosis in ARPE-19 cells. CONCLUSION circ-CARD6 can inhibit oxidative stress and apoptosis by regulating the miR-29b-3p/PRDX6/PI3K/Akt axis.
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Affiliation(s)
- Xinyu Fan
- Department of Ophthalmology, The 2nd Affiliated Hospital of Kunming Medical University, Kunming, 650101, Yunnan, China
| | - Yanni Yang
- Ophthalmology Department, The Second Hospital of Ningbo, Ningbo, 315010, Zhejiang, China
| | - Guojiu Wu
- Department of Ophthalmology, The 2nd Affiliated Hospital of Kunming Medical University, Kunming, 650101, Yunnan, China
| | - Yanbo Kong
- Department of Ophthalmology, The 2nd Affiliated Hospital of Kunming Medical University, Kunming, 650101, Yunnan, China
| | - Yuanping Zhang
- Department of Ophthalmology, The 2nd Affiliated Hospital of Kunming Medical University, Kunming, 650101, Yunnan, China
| | - Xu Zha
- Department of Ophthalmology, The 2nd Affiliated Hospital of Kunming Medical University, Kunming, 650101, Yunnan, China.
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4
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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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5
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Duarte FV, Ciampi D, Duarte CB. Mitochondria as central hubs in synaptic modulation. Cell Mol Life Sci 2023; 80:173. [PMID: 37266732 DOI: 10.1007/s00018-023-04814-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 05/10/2023] [Accepted: 05/19/2023] [Indexed: 06/03/2023]
Abstract
Mitochondria are present in the pre- and post-synaptic regions, providing the energy required for the activity of these very specialized neuronal compartments. Biogenesis of synaptic mitochondria takes place in the cell body, and these organelles are then transported to the synapse by motor proteins that carry their cargo along microtubule tracks. The transport of mitochondria along neurites is a highly regulated process, being modulated by the pattern of neuronal activity and by extracellular cues that interact with surface receptors. These signals act by controlling the distribution of mitochondria and by regulating their activity. Therefore, mitochondria activity at the synapse allows the integration of different signals and the organelles are important players in the response to synaptic stimulation. Herein we review the available evidence regarding the regulation of mitochondrial dynamics by neuronal activity and by neuromodulators, and how these changes in the activity of mitochondria affect synaptic communication.
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Affiliation(s)
- Filipe V Duarte
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
- III - Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Daniele Ciampi
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
- IRCCS Humanitas Research Hospital, Rozzano, Milan, Italy
| | - Carlos B Duarte
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.
- Department of Life Sciences, University of Coimbra, Coimbra, Portugal.
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6
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Morris S, Molina-Riquelme I, Barrientos G, Bravo F, Aedo G, Gómez W, Lagos D, Verdejo H, Peischard S, Seebohm G, Psathaki OE, Eisner V, Busch KB. Inner mitochondrial membrane structure and fusion dynamics are altered in senescent human iPSC-derived and primary rat cardiomyocytes. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2023; 1864:148949. [PMID: 36493857 DOI: 10.1016/j.bbabio.2022.148949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 11/17/2022] [Accepted: 11/30/2022] [Indexed: 12/12/2022]
Abstract
Dysfunction of the aging heart is a major cause of death in the human population. Amongst other tasks, mitochondria are pivotal to supply the working heart with ATP. The mitochondrial inner membrane (IMM) ultrastructure is tailored to meet these demands and to provide nano-compartments for specific tasks. Thus, function and morphology are closely coupled. Senescent cardiomyocytes from the mouse heart display alterations of the inner mitochondrial membrane. To study the relation between inner mitochondrial membrane architecture, dynamics and function is hardly possible in living organisms. Here, we present two cardiomyocyte senescence cell models that allow in cellular studies of mitochondrial performance. We show that doxorubicin treatment transforms human iPSC-derived cardiomyocytes and rat neonatal cardiomyocytes in an aged phenotype. The treated cardiomyocytes display double-strand breaks in the nDNA, have β-galactosidase activity, possess enlarged nuclei, and show p21 upregulation. Most importantly, they also display a compromised inner mitochondrial structure. This prompted us to test whether the dynamics of the inner membrane was also altered. We found that the exchange of IMM components after organelle fusion was faster in doxorubicin-treated cells than in control cells, with no change in mitochondrial fusion dynamics at the meso-scale. Such altered IMM morphology and dynamics may have important implications for local OXPHOS protein organization, exchange of damaged components, and eventually the mitochondrial bioenergetics function of the aged cardiomyocyte.
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Affiliation(s)
- Silke Morris
- Institute of Integrative Cell Biology and Physiology, Schlossplatz 5, Faculty of Biology, University of Muenster, 48149 Muenster, North-Rhine-Westphalia, Germany
| | - Isidora Molina-Riquelme
- Departmento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Avda. Libertador Bernardo O´Higgins 340, Santiago de Chile, Chile
| | - Gonzalo Barrientos
- Departmento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Avda. Libertador Bernardo O´Higgins 340, Santiago de Chile, Chile
| | - Francisco Bravo
- Departmento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Avda. Libertador Bernardo O´Higgins 340, Santiago de Chile, Chile
| | - Geraldine Aedo
- Departmento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Avda. Libertador Bernardo O´Higgins 340, Santiago de Chile, Chile
| | - Wileidy Gómez
- Departmento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Avda. Libertador Bernardo O´Higgins 340, Santiago de Chile, Chile
| | - Daniel Lagos
- Departmento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Avda. Libertador Bernardo O´Higgins 340, Santiago de Chile, Chile
| | - Hugo Verdejo
- Facultad de Medicina, División de Enfermedades Cardiovasculares, Pontificia Universidad Católica de Chile, Avda. Libertador Bernardo O´Higgins 340, Santiago de Chile, Chile
| | - Stefan Peischard
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, D-48149 Münster, North-Rhine-Westphalia, Germany
| | - Guiscard Seebohm
- Institute for Genetics of Heart Diseases (IfGH), Department of Cardiovascular Medicine, University Hospital Münster, D-48149 Münster, North-Rhine-Westphalia, Germany
| | - Olympia Ekaterini Psathaki
- Center of Cellular Nanoanalytics, Integrated Bioimaging Facility, University of Osnabrück, 49076 Osnabrück, Lower Saxony, Germany
| | - Verónica Eisner
- Departmento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Avda. Libertador Bernardo O´Higgins 340, Santiago de Chile, Chile.
| | - Karin B Busch
- Institute of Integrative Cell Biology and Physiology, Schlossplatz 5, Faculty of Biology, University of Muenster, 48149 Muenster, North-Rhine-Westphalia, Germany.
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7
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Eliseeva DD, Kalashnikova AK, Bryukhov VV, Andreeva NA, Zhorzholadze NV, Murakhovskaya YK, Krilova TD, Tsygankova PG, Zakharova MN, Sheremet NL. [Hereditary optic neuropathy associated with demyelinating diseases of the central nervous system]. Zh Nevrol Psikhiatr Im S S Korsakova 2023; 123:122-132. [PMID: 37560844 DOI: 10.17116/jnevro2023123072122] [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: 08/11/2023]
Abstract
Demyelinating optic neuritis and hereditary optic neuropathy (HON) take a leading place among the diseases, the leading clinical syndrome of which is bilateral optic neuropathy with a simultaneous or sequential significant decrease in visual acuity. Optic neuritis can occur at the onset or be one of the syndromes within multiple sclerosis (MS), neuromyelitis optica spectrum disorders (NMOSD), and myelin oligodendrocyte glycoprotein (MOG) antibody disease (MOGAD). HON are a group of neurodegenerative diseases, among which the most common variants are Leber's hereditary optic neuropathy (LHON), associated with mitochondrial DNA (mtDNA) mutations, and autosomal recessive optic neuropathy (ARON), caused by nuclear DNA (nDNA) mutations in DNAJC30. There are phenotypes of LHON «plus», one of which is the association of HON and CNS demyelination in the same patient. In such cases, the diagnosis of each of these diseases causes significant difficulties, due to the fact that in some cases there are clinical and radiological coincidences between demyelinating and hereditary mitochondrial diseases.
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Affiliation(s)
| | - A K Kalashnikova
- Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia
| | | | - N A Andreeva
- Research Institute of Eye Diseases, Moscow, Russia
| | | | | | - T D Krilova
- Research Centre for Medical Genetics, Moscow, Russia
| | | | | | - N L Sheremet
- Research Institute of Eye Diseases, Moscow, Russia
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8
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Sanz-Morello B, Ahmadi H, Vohra R, Saruhanian S, Freude KK, Hamann S, Kolko M. Oxidative Stress in Optic Neuropathies. Antioxidants (Basel) 2021; 10:1538. [PMID: 34679672 PMCID: PMC8532958 DOI: 10.3390/antiox10101538] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 09/07/2021] [Accepted: 09/12/2021] [Indexed: 01/23/2023] Open
Abstract
Increasing evidence indicates that changes in the redox system may contribute to the pathogenesis of multiple optic neuropathies. Optic neuropathies are characterized by the neurodegeneration of the inner-most retinal neurons, the retinal ganglion cells (RGCs), and their axons, which form the optic nerve. Often, optic neuropathies are asymptomatic until advanced stages, when visual impairment or blindness is unavoidable despite existing treatments. In this review, we describe systemic and, whenever possible, ocular redox dysregulations observed in patients with glaucoma, ischemic optic neuropathy, optic neuritis, hereditary optic neuropathies (i.e., Leber's hereditary optic neuropathy and autosomal dominant optic atrophy), nutritional and toxic optic neuropathies, and optic disc drusen. We discuss aspects related to anti/oxidative stress biomarkers that need further investigation and features related to study design that should be optimized to generate more valuable and comparable results. Understanding the role of oxidative stress in optic neuropathies can serve to develop therapeutic strategies directed at the redox system to arrest the neurodegenerative processes in the retina and RGCs and ultimately prevent vision loss.
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Affiliation(s)
- Berta Sanz-Morello
- Eye Translational Research Unit, Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark; (B.S.-M.); (H.A.); (R.V.)
| | - Hamid Ahmadi
- Eye Translational Research Unit, Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark; (B.S.-M.); (H.A.); (R.V.)
- Department of Ophthalmology, Rigshospitalet, 2600 Glostrup, Denmark;
| | - Rupali Vohra
- Eye Translational Research Unit, Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark; (B.S.-M.); (H.A.); (R.V.)
- Group of Stem Cell Models for Studies of Neurodegenerative Diseases, Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 1870 Frederiksberg, Denmark; (S.S.); (K.K.F.)
| | - Sarkis Saruhanian
- Group of Stem Cell Models for Studies of Neurodegenerative Diseases, Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 1870 Frederiksberg, Denmark; (S.S.); (K.K.F.)
| | - Kristine Karla Freude
- Group of Stem Cell Models for Studies of Neurodegenerative Diseases, Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 1870 Frederiksberg, Denmark; (S.S.); (K.K.F.)
| | - Steffen Hamann
- Department of Ophthalmology, Rigshospitalet, 2600 Glostrup, Denmark;
| | - Miriam Kolko
- Eye Translational Research Unit, Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark; (B.S.-M.); (H.A.); (R.V.)
- Department of Ophthalmology, Rigshospitalet, 2600 Glostrup, Denmark;
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9
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Zinsmaier KE. Mitochondrial Miro GTPases coordinate mitochondrial and peroxisomal dynamics. Small GTPases 2021; 12:372-398. [PMID: 33183150 PMCID: PMC8583064 DOI: 10.1080/21541248.2020.1843957] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 10/22/2020] [Accepted: 10/26/2020] [Indexed: 12/18/2022] Open
Abstract
Mitochondria and peroxisomes are highly dynamic, multifunctional organelles. Both perform key roles for cellular physiology and homoeostasis by mediating bioenergetics, biosynthesis, and/or signalling. To support cellular function, they must be properly distributed, of proper size, and be able to interact with other organelles. Accumulating evidence suggests that the small atypical GTPase Miro provides a central signalling node to coordinate mitochondrial as well as peroxisomal dynamics. In this review, I summarize our current understanding of Miro-dependent functions and molecular mechanisms underlying the proper distribution, size and function of mitochondria and peroxisomes.
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Affiliation(s)
- Konrad E. Zinsmaier
- Departments of Neuroscience and Molecular and Cellular Biology, University of Arizona, Tucson, AZ, USA
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10
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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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11
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The Multifaceted Roles of Zinc in Neuronal Mitochondrial Dysfunction. Biomedicines 2021; 9:biomedicines9050489. [PMID: 33946782 PMCID: PMC8145363 DOI: 10.3390/biomedicines9050489] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 03/05/2021] [Accepted: 03/07/2021] [Indexed: 12/17/2022] Open
Abstract
Zinc is a highly abundant cation in the brain, essential for cellular functions, including transcription, enzymatic activity, and cell signaling. However, zinc can also trigger injurious cascades in neurons, contributing to the pathology of neurodegenerative diseases. Mitochondria, critical for meeting the high energy demands of the central nervous system (CNS), are a principal target of the deleterious actions of zinc. An increasing body of work suggests that intracellular zinc can, under certain circumstances, contribute to neuronal damage by inhibiting mitochondrial energy processes, including dissipation of the mitochondrial membrane potential (MMP), leading to ATP depletion. Additional consequences of zinc-mediated mitochondrial damage include reactive oxygen species (ROS) generation, mitochondrial permeability transition, and excitotoxic calcium deregulation. Zinc can also induce mitochondrial fission, resulting in mitochondrial fragmentation, as well as inhibition of mitochondrial motility. Here, we review the known mechanisms responsible for the deleterious actions of zinc on the organelle, within the context of neuronal injury associated with neurodegenerative processes. Elucidating the critical contributions of zinc-induced mitochondrial defects to neurotoxicity and neurodegeneration may provide insight into novel therapeutic targets in the clinical setting.
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Kyriakoudi S, Drousiotou A, Petrou PP. When the Balance Tips: Dysregulation of Mitochondrial Dynamics as a Culprit in Disease. Int J Mol Sci 2021; 22:ijms22094617. [PMID: 33924849 PMCID: PMC8124286 DOI: 10.3390/ijms22094617] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 04/23/2021] [Accepted: 04/25/2021] [Indexed: 12/12/2022] Open
Abstract
Mitochondria are dynamic organelles, the morphology of which is tightly linked to their functions. The interplay between the coordinated events of fusion and fission that are collectively described as mitochondrial dynamics regulates mitochondrial morphology and adjusts mitochondrial function. Over the last few years, accruing evidence established a connection between dysregulated mitochondrial dynamics and disease development and progression. Defects in key components of the machinery mediating mitochondrial fusion and fission have been linked to a wide range of pathological conditions, such as insulin resistance and obesity, neurodegenerative diseases and cancer. Here, we provide an update on the molecular mechanisms promoting mitochondrial fusion and fission in mammals and discuss the emerging association of disturbed mitochondrial dynamics with human disease.
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Affiliation(s)
- Styliana Kyriakoudi
- Department of Biochemical Genetics, The Cyprus Institute of Neurology and Genetics, P.O. Box 23462, Nicosia 1683, Cyprus; (S.K.); (A.D.)
| | - Anthi Drousiotou
- Department of Biochemical Genetics, The Cyprus Institute of Neurology and Genetics, P.O. Box 23462, Nicosia 1683, Cyprus; (S.K.); (A.D.)
- Cyprus School of Molecular Medicine, P.O. Box 23462, Nicosia 1683, Cyprus
| | - Petros P. Petrou
- Department of Biochemical Genetics, The Cyprus Institute of Neurology and Genetics, P.O. Box 23462, Nicosia 1683, Cyprus; (S.K.); (A.D.)
- Cyprus School of Molecular Medicine, P.O. Box 23462, Nicosia 1683, Cyprus
- Correspondence:
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Antonucci S, Di Sante M, Tonolo F, Pontarollo L, Scalcon V, Alanova P, Menabò R, Carpi A, Bindoli A, Rigobello MP, Giorgio M, Kaludercic N, Di Lisa F. The Determining Role of Mitochondrial Reactive Oxygen Species Generation and Monoamine Oxidase Activity in Doxorubicin-Induced Cardiotoxicity. Antioxid Redox Signal 2021; 34:531-550. [PMID: 32524823 PMCID: PMC7885901 DOI: 10.1089/ars.2019.7929] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Aims: Doxorubicin cardiomyopathy is a lethal pathology characterized by oxidative stress, mitochondrial dysfunction, and contractile impairment, leading to cell death. Although extensive research has been done to understand the pathophysiology of doxorubicin cardiomyopathy, no effective treatments are available. We investigated whether monoamine oxidases (MAOs) could be involved in doxorubicin-derived oxidative stress, and in the consequent mitochondrial, cardiomyocyte, and cardiac dysfunction. Results: We used neonatal rat ventricular myocytes (NRVMs) and adult mouse ventricular myocytes (AMVMs). Doxorubicin alone (i.e., 0.5 μM doxorubicin) or in combination with H2O2 induced an increase in mitochondrial formation of reactive oxygen species (ROS), which was prevented by the pharmacological inhibition of MAOs in both NRVMs and AMVMs. The pharmacological approach was supported by the genetic ablation of MAO-A in NRVMs. In addition, doxorubicin-derived ROS caused lipid peroxidation and alterations in mitochondrial function (i.e., mitochondrial membrane potential, permeability transition, redox potential), mitochondrial morphology (i.e., mitochondrial distribution and perimeter), sarcomere organization, intracellular [Ca2+] homeostasis, and eventually cell death. All these dysfunctions were abolished by MAO inhibition. Of note, in vivo MAO inhibition prevented chamber dilation and cardiac dysfunction in doxorubicin-treated mice. Innovation and Conclusion: This study demonstrates that the severe oxidative stress induced by doxorubicin requires the involvement of MAOs, which modulate mitochondrial ROS generation. MAO inhibition provides evidence that mitochondrial ROS formation is causally linked to all disorders caused by doxorubicin in vitro and in vivo. Based upon these results, MAO inhibition represents a novel therapeutic approach for doxorubicin cardiomyopathy.
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Affiliation(s)
| | - Moises Di Sante
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Federica Tonolo
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Laura Pontarollo
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Valeria Scalcon
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Petra Alanova
- Department of Biomedical Sciences, University of Padova, Padova, Italy.,Institute for Physiology, Czech Academy of Sciences, Prague, Czech Republic
| | - Roberta Menabò
- Neuroscience Institute, National Research Council of Italy (CNR), Padova, Italy
| | - Andrea Carpi
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Alberto Bindoli
- Neuroscience Institute, National Research Council of Italy (CNR), Padova, Italy
| | | | - Marco Giorgio
- Department of Biomedical Sciences, University of Padova, Padova, Italy.,European Institute of Oncology (IEO), Milan, Italy
| | - Nina Kaludercic
- Neuroscience Institute, National Research Council of Italy (CNR), Padova, Italy
| | - Fabio Di Lisa
- Department of Biomedical Sciences, University of Padova, Padova, Italy.,Neuroscience Institute, National Research Council of Italy (CNR), Padova, Italy
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Sun S, Erchova I, Sengpiel F, Votruba M. Opa1 Deficiency Leads to Diminished Mitochondrial Bioenergetics With Compensatory Increased Mitochondrial Motility. Invest Ophthalmol Vis Sci 2021; 61:42. [PMID: 32561926 PMCID: PMC7415319 DOI: 10.1167/iovs.61.6.42] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Purpose Retinal ganglion cells (RGCs) are susceptible to mitochondrial deficits and also the major cell type affected in patients with mutations in the OPA1 gene in autosomal dominant optic atrophy (ADOA). Here, we characterized mitochondria in RGCs in vitro from a heterozygous B6; C3-Opa1Q285STOP (Opa1+/−) mouse model to investigate mitochondrial changes underlying the pathology in ADOA. Methods Mouse RGCs were purified from wild-type and Opa1+/− mouse retina by two-step immunopanning. The mitochondria in neurites of RGCs were labeled with MitoTracker Red for structure and motility measurement by time-lapse imaging. Mitochondrial bioenergetics were determined by the real-time measurement of oxygen consumption rate using a Seahorse XFe 96 Extracellular Flux Analyzer. Results We observed a significant decrease in mitochondrial length in Opa1+/− RGCs with a remarkably higher proportion and density of motile mitochondria along the neurites. We also observed an increased transport velocity with a higher number of contacts between mitochondria in Opa1+/− RGC neurites. The oxygen consumption assays showed a severe impairment in basal respiration, Adenosine triphosphate-linked (ATP-linked) oxygen consumption, as well as reserve respiratory capacity, in RGCs from Opa1+/− mouse retina. Conclusions Opa1 deficiency leads to significant fragmentation of mitochondrial morphology, activation of mitochondrial motility and impaired respiratory function in RGCs from the B6; C3-Opa1Q285STOP mouse model. This highlights the significant alterations in the intricate interplay between mitochondrial morphology, motility, and energy production in RGCs with Opa1 deficiency long before the onset of clinical symptoms of the pathology.
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Effects of Aging on Expression of Mic60 and OPA1 and Mitochondrial Morphology in Myocardium of Tibetan Sheep. Animals (Basel) 2020; 10:ani10112160. [PMID: 33233488 PMCID: PMC7699535 DOI: 10.3390/ani10112160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 11/18/2020] [Indexed: 12/04/2022] Open
Abstract
Simple Summary Mitochondria play a crucial role in the adaptation to high altitude hypoxia environment in Tibetan sheep, and the changes of its morphology and structure directly affect its function. OPA1 and Mic60 are important mitochondria-shaping proteins that work together to regulate the morphology of mitochondrial inner membrane and cristae. It has been shown that aging affects the expression of OPA1 and Mic60 in mice, but it has not been investigated in sheep and hence it is not known whether it might affect the ultrastructure of mitochondria. In this context, reverse transcription-quantitative PCR (RT-qPCR), enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry method were used to measure the expression of Mic60 and OPA1 genes and proteins in myocardium of adult and aged Tibetan sheep, and the ultrastructure of mitochondria were compared by transmission electron microscope. The results suggest that aging can reduces the expression of Mic60 and OPA1 genes and OPA1 protein, which can affect the mitochondrial function. Abstract In order to investigate the effects of aging on the expression of Mic60 and OPA1 and mitochondrial morphology in plateau animals, the expression of Mic60 and OPA1 genes and proteins, and the morphology of mitochondria in the myocardium of adult and aged Tibetan sheep were investigated. The expression of Mic60 and OPA1 genes and OPA1 protein were higher (p < 0.05) in the myocardium of adult Tibetan sheep than in those of the aged ones. The number of mitochondrial cristae in the myocardium of adult was higher than that in aged (p < 0.05). The density of mitochondria in the myocardium of adult was higher than that in aged (p < 0.01). Compared with the adult Tibetan sheep, the mitochondrial crista of aged were relatively sparse, the crista membrane was wide, and the mitochondria were not closely linked, showing fragmentation. These results suggest that the myocardial mitochondria of the adult have better energy supply ability, indicating that aging can lead to the weakening of oxygen supply in the myocardial mitochondria of Tibetan sheep.
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Trevisan T, Pendin D, Montagna A, Bova S, Ghelli AM, Daga A. Manipulation of Mitochondria Dynamics Reveals Separate Roles for Form and Function in Mitochondria Distribution. Cell Rep 2019; 23:1742-1753. [PMID: 29742430 DOI: 10.1016/j.celrep.2018.04.017] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 03/01/2018] [Accepted: 04/02/2018] [Indexed: 01/09/2023] Open
Abstract
Mitochondria shape is controlled by membrane fusion and fission mediated by mitofusins, Opa1, and Drp1, whereas mitochondrial motility relies on microtubule motors. These processes govern mitochondria subcellular distribution, whose defects are emphasized in neurons because of their polarized structure. We have studied how perturbation of the fusion/fission balance affects mitochondria distribution in Drosophila axons. Knockdown of Marf or Opa1 resulted in progressive loss of distal mitochondria and in a distinct oxidative phosphorylation and membrane potential deficit. Downregulation of Drp1 rescued the lethality and bioenergetic defect caused by neuronal Marf RNAi, but induced only a modest restoration of axonal mitochondria distribution. Surprisingly, Drp1 knockdown rescued fragmentation and fully restored aberrant distribution of axonal mitochondria produced by Opa1 RNAi; however, Drp1 knockdown did not improve viability or mitochondria function. Our data show that proper morphology is critical for proper axonal mitochondria distribution independent of bioenergetic efficiency. The health of neurons largely depends on mitochondria function, but does not depend on shape or distribution.
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Affiliation(s)
- Tatiana Trevisan
- Laboratory of Molecular Biology, Scientific Institute IRCCS E. Medea, Bosisio Parini, Lecco, Italy
| | - Diana Pendin
- Laboratory of Molecular Biology, Scientific Institute IRCCS E. Medea, Bosisio Parini, Lecco, Italy
| | - Aldo Montagna
- Laboratory of Molecular Biology, Scientific Institute IRCCS E. Medea, Bosisio Parini, Lecco, Italy
| | - Sergio Bova
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy
| | - Anna Maria Ghelli
- Department of Pharmacy and Biotechnology, University of Bologna, 40127 Bologna, Italy
| | - Andrea Daga
- Laboratory of Molecular Biology, Scientific Institute IRCCS E. Medea, Bosisio Parini, Lecco, Italy.
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17
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Tulli S, Del Bondio A, Baderna V, Mazza D, Codazzi F, Pierson TM, Ambrosi A, Nolte D, Goizet C, Toro C, Baets J, Deconinck T, DeJonghe P, Mandich P, Casari G, Maltecca F. Pathogenic variants in the AFG3L2 proteolytic domain cause SCA28 through haploinsufficiency and proteostatic stress-driven OMA1 activation. J Med Genet 2019; 56:499-511. [PMID: 30910913 PMCID: PMC6678042 DOI: 10.1136/jmedgenet-2018-105766] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 02/05/2019] [Accepted: 03/03/2019] [Indexed: 12/18/2022]
Abstract
Background Spinocerebellar ataxia type 28 (SCA28) is a dominantly inherited neurodegenerative disease caused by pathogenic variants in AFG3L2. The AFG3L2 protein is a subunit of mitochondrial m-AAA complexes involved in protein quality control. Objective of this study was to determine the molecular mechanisms of SCA28, which has eluded characterisation to date. Methods We derived SCA28 patient fibroblasts carrying different pathogenic variants in the AFG3L2 proteolytic domain (missense: the newly identified p.F664S and p.M666T, p.G671R, p.Y689H and a truncating frameshift p.L556fs) and analysed multiple aspects of mitochondrial physiology. As reference of residual m-AAA activity, we included SPAX5 patient fibroblasts with homozygous p.Y616C pathogenic variant, AFG3L2+/− HEK293 T cells by CRISPR/Cas9-genome editing and Afg3l2−/− murine fibroblasts. Results We found that SCA28 cells carrying missense changes have normal levels of assembled m-AAA complexes, while the cells with a truncating pathogenic variant had only half of this amount. We disclosed inefficient mitochondrial fusion in SCA28 cells caused by increased OPA1 processing operated by hyperactivated OMA1. Notably, we found altered mitochondrial proteostasis to be the trigger of OMA1 activation in SCA28 cells, with pharmacological attenuation of mitochondrial protein synthesis resulting in stabilised levels of OMA1 and OPA1 long forms, which rescued mitochondrial fusion efficiency. Secondary to altered mitochondrial morphology, mitochondrial calcium uptake resulted decreased in SCA28 cells. Conclusion Our data identify the earliest events in SCA28 pathogenesis and open new perspectives for therapy. By identifying similar mitochondrial phenotypes between SCA28 cells and AFG3L2+/− cells, our results support haploinsufficiency as the mechanism for the studied pathogenic variants.
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Affiliation(s)
- Susanna Tulli
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Andrea Del Bondio
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Valentina Baderna
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Davide Mazza
- Experimental Imaging Center, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Franca Codazzi
- Università Vita-Salute San Raffaele, Milan, Italy.,Division of Neuroscience, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Tyler Mark Pierson
- Departments of Pediatrics and Neurology and the Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | | | - Dagmar Nolte
- Department of Medicine, Institute for Human Genetics, Justus-Liebig-University Giessen, Giessen, Germany
| | - Cyril Goizet
- Centre de Reference Neurogenetique, Service de Genetique Medicale, CHU Bordeaux, Bordeaux, France.,Laboratoire MRGM, INSERM U1211, Bordeaux, France
| | - Camilo Toro
- Undiagnosed Disease Program, Common Fund, Office of the Director, National Institutes of Health, Bethesda, Maryland, USA
| | - Jonathan Baets
- Neurogenetics Group and Institute Born-Bunge, University of Antwerp, Antwerpen, Belgium.,Neuromuscular Reference Centre, Antwerp University Hospital, Antwerpen, Belgium
| | - Tine Deconinck
- Neurogenetics Group and Institute Born-Bunge, University of Antwerp, Antwerpen, Belgium.,Neuromuscular Reference Centre, Antwerp University Hospital, Antwerpen, Belgium
| | - Peter DeJonghe
- Neurogenetics Group and Institute Born-Bunge, University of Antwerp, Antwerpen, Belgium.,Neuromuscular Reference Centre, Antwerp University Hospital, Antwerpen, Belgium
| | - Paola Mandich
- DINOGMI, University of Genoa and IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Giorgio Casari
- Università Vita-Salute San Raffaele, Milan, Italy.,Telethon Institute of Genetics and Medicine, Naples, Italy
| | - Francesca Maltecca
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, Milan, Italy.,Università Vita-Salute San Raffaele, Milan, Italy
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18
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Tapias V, McCoy JL, Greenamyre JT. Phenothiazine normalizes the NADH/NAD + ratio, maintains mitochondrial integrity and protects the nigrostriatal dopamine system in a chronic rotenone model of Parkinson's disease. Redox Biol 2019; 24:101164. [PMID: 30925294 PMCID: PMC6440170 DOI: 10.1016/j.redox.2019.101164] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 03/04/2019] [Accepted: 03/07/2019] [Indexed: 12/21/2022] Open
Abstract
Impaired mitochondrial function has been associated with the etiopathogenesis of Parkinson's disease (PD). Sustained inhibition of complex I produces mitochondrial dysfunction, which is related to oxidative injury and nigrostriatal dopamine (DA) neurodegeneration. This study aimed to identify disease-modifying treatments for PD. Unsubstituted phenothiazine (PTZ) is a small and uncharged aromatic imine that readily crosses the blood-brain barrier. PTZ lacks significant DA receptor-binding activity and, in the nanomolar range, exhibits protective effects via its potent free radical scavenging and anti-inflammatory activities. Given that DAergic neurons are highly vulnerable to oxidative damage and inflammation, we hypothesized that administration of PTZ might confer neuroprotection in different experimental models of PD. Our findings showed that PTZ rescues rotenone (ROT) toxicity in primary ventral midbrain neuronal cultures by preserving neuronal integrity and reducing protein thiol oxidation. Long-term treatment with PTZ improved animal weight, survival rate, and behavioral deficits in ROT-lesioned rats. PTZ protected DA content and fiber density in the striatum and DA neurons in the SN against the deleterious effects of ROT. Mitochondrial dysfunction, axonal impairment, oxidative insult, and inflammatory response were attenuated with PTZ therapy. Furthermore, we have provided a new insight into the molecular mechanism underlying the neuroprotective effects of PTZ.
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Affiliation(s)
- Victor Tapias
- Department of Neurology, USA; Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh, Pittsburgh, PA 15260, USA.
| | - Jennifer L McCoy
- Department of Neurology, USA; Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - J Timothy Greenamyre
- Department of Neurology, USA; Pittsburgh Institute for Neurodegenerative Diseases, University of Pittsburgh, Pittsburgh, PA 15260, USA
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Bai Y, Wang S, Wu F, Xie X, Wang Y, Yang Y. The Changes of Mitochondria in Substantia Nigra and Anterior Cerebral Cortex of Hepatic Encephalopathy Induced by Thioacetamide. Anat Rec (Hoboken) 2019; 302:1169-1177. [PMID: 30290401 PMCID: PMC6899860 DOI: 10.1002/ar.23932] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 01/22/2018] [Accepted: 02/03/2018] [Indexed: 01/10/2023]
Abstract
Hepatic encephalopathy (HE) is a neuropsychiatric syndrome resulting from chronic or acute liver failure. Under the condition of HE, various factors such as reactive oxygen species, inflammatory factors, ammonia poisoning and amino acids alteration lead to changes of mitochondria. Selective depletion of damaged mitochondrion is essential for maintaining the morphology and function of mitochondria and cells. In this study, molecular biology analysis was used to analyze the mitochondrial morphology in the substantia nigra (SN) and anterior cerebral cortex (ACC) of the HE mice. The results revealed that the drp1, mfn1 and mfn2 increased in mRNA level of SN, which indicated the changes of mitochondrial morphology in HE mice. The drp1 and mfn2 genes were up‐regulated, then, the Opa1 exhibited no significant change in the ACC of HE mice. Further study demonstrated that the mitochondrial autophagy related genes, pink1 and parkin, increased in SN, while the parkin reduced in ACC of HE mice. In addition, uncoupling protein (ucp2) increased in mRNA level of SN and ACC, and the ucp4 had no change or reduced in SN and ACC, respectively. These findings suggested that the mitochondrial dynamics is different in the SN and ACC of HE mice. Therefore, our results indicated that mitochondrial dynamics provided a potential treatment strategy for HE through the fission, fusion and autophagy of genes. Anat Rec, 302:1169–1177, 2019. © 2018 The Authors. The Anatomical Record published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists.
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Affiliation(s)
- Yunhu Bai
- Department of Hepatobiliary Surgery, Xi-Jing Hospital, Fourth Military Medical University, Xi'an, China.,Department of general surgery, People's Liberation Army's 153rd hospital, Zhengzhou, China
| | - Shengming Wang
- Department of Anatomy and K.K. Leung Brain Research Centre, Fourth Military Medical University, Xi'an, China
| | - Feifei Wu
- Department of Anatomy and K.K. Leung Brain Research Centre, Fourth Military Medical University, Xi'an, China
| | - Xiangjun Xie
- Department of Preventive Medicine, The Fourth Military Medical University, Xi'an, China
| | - Yayun Wang
- Department of Anatomy and K.K. Leung Brain Research Centre, Fourth Military Medical University, Xi'an, China
| | - Yanling Yang
- Department of Hepatobiliary Surgery, Xi-Jing Hospital, Fourth Military Medical University, Xi'an, China
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20
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Expression of OPA1 and Mic60 genes and their association with mitochondrial cristae morphology in Tibetan sheep. Cell Tissue Res 2019; 376:273-279. [DOI: 10.1007/s00441-018-2975-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 11/29/2018] [Indexed: 10/27/2022]
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21
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Loro E, Bisetto S, Khurana TS. Mitochondrial ultrastructural adaptations in fast muscles of mice lacking IL15RA. J Cell Sci 2018; 131:jcs.218313. [PMID: 30301784 DOI: 10.1242/jcs.218313] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 10/01/2018] [Indexed: 12/18/2022] Open
Abstract
The pro-inflammatory cytokine interleukin-15 (IL15) and its receptor α (IL15RA) participate in the regulation of musculoskeletal function and metabolism. Deletion of the Il15ra gene in mice increases spontaneous activity, improves fatigue resistance in the glycolytic extensor digitorum longus (EDL) and protects from diet-induced obesity. In humans, IL15RA single-nucleotide polymorphisms (SNPs) have been linked to muscle strength, metabolism and performance in elite endurance athletes. Taken together, these features suggest a possible role for IL15RA in muscle mitochondrial structure and function. Here, we have investigated the consequences of loss of IL15RA on skeletal muscle fiber-type properties and mitochondrial ultrastructure. Immunostaining of the EDL for myosin heavy chain (MyHC) isoforms revealed no significant changes in fiber type. Electron microscopy (EM) analysis of the EDL indicated an overall higher mitochondria content, and increased cristae density in subsarcolemmal and A-band mitochondrial subpopulations. The higher cristae density in Il15ra -/- mitochondria was associated with higher OPA1 and cardiolipin levels. Overall, these data extend our understanding of the role of IL15RA signaling in muscle oxidative metabolism and adaptation to exercise.
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Affiliation(s)
- Emanuele Loro
- Department of Physiology and Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Sara Bisetto
- Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Tejvir S Khurana
- Department of Physiology and Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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22
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Ham M, Han J, Osann K, Smith M, Kimonis V. Meta-analysis of genotype-phenotype analysis of OPA1 mutations in autosomal dominant optic atrophy. Mitochondrion 2018; 46:262-269. [PMID: 30165240 DOI: 10.1016/j.mito.2018.07.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 05/20/2018] [Accepted: 07/31/2018] [Indexed: 01/21/2023]
Abstract
Autosomal Dominant Optic Atrophy (ADOA) is a neuro-ophthalmic disease characterized by progressive bilateral vision loss, pallor of the optic disc, central vision loss, and impairment of color vision. Additionally, a small percentage of patients experience hearing loss and ataxia, while recent studies suggest disruption of cardiac and neuromuscular functions. In order to obtain a better understanding of the genotype-phenotype correlation of the various mutations in the optic atrophy 1 (OPA1) gene, we obtained both clinical and genetic information of ADOA patients from published reports. We conducted a systematic review of published OPA1 literature and identified 408 individuals with confirmed OPA1 mutations, 120 of whom reported extra-ocular (ADOA 'plus') manifestations through their descriptions of visual and multi-systemic symptoms. Our results show that there is a significant variation in frequency of the specific exons involved between the ADOA classic and ADOA 'plus' patients. Classic ADOA groups were more likely to have mutations in exon 8 and 9, while ADOA 'plus' groups were more likely to have mutations in exons 14, 15 and 17. Additional comparisons revealed significant differences between mutation types/domains and specific ADOA 'plus' manifestations. We also found that individuals with maternally inherited OPA1 mutations were significantly more likely to develop 'plus' manifestations than those with paternally inherited mutations. Overall, this study provides novel information regarding genotype-phenotype correlations of ADOA which warrants additional recommendations added to the current clinical management of ADOA patients.
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Affiliation(s)
- Michelle Ham
- Division of Genetics and Genomic Medicine, Department of Pediatrics, University of California, Irvine, CA, USA
| | - Julia Han
- Division of Genetics and Genomic Medicine, Department of Pediatrics, University of California, Irvine, CA, USA
| | - Kathryn Osann
- Department of Medicine, Division of Hematology-Oncology, University of California, Irvine, CA, USA
| | - Moyra Smith
- Division of Genetics and Genomic Medicine, Department of Pediatrics, University of California, Irvine, CA, USA
| | - Virginia Kimonis
- Division of Genetics and Genomic Medicine, Department of Pediatrics, University of California, Irvine, CA, USA.
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23
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Phosphatases control PKA-dependent functional microdomains at the outer mitochondrial membrane. Proc Natl Acad Sci U S A 2018; 115:E6497-E6506. [PMID: 29941564 PMCID: PMC6048485 DOI: 10.1073/pnas.1806318115] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The selective phosphorylation of spatially distinct PKA targets is key for the pleiotropy of the cAMP cascade. This characteristic of the pathway is currently attributed to the ability of phosphodiesterases or adenylate cyclases to create subcellular sites (microdomains) where the concentration of cAMP is distinct from that of the surrounding areas. The role of phosphatases in this process has not been tested. Here we show that limited access of phosphatases to the PKA targets present at the outer mitochondrial membrane generates distinct microdomains of PKA phosphorylated proteins despite there being no differences in the local cAMP levels. These results describe an alternative mechanism capable of generating functional cAMP/PKA-dependent microdomains and may be extrapolated to the compartmentalization of other kinase-dependent events. Evidence supporting the heterogeneity in cAMP and PKA signaling is rapidly accumulating and has been largely attributed to the localization or activity of adenylate cyclases, phosphodiesterases, and A-kinase–anchoring proteins in different cellular subcompartments. However, little attention has been paid to the possibility that, despite homogeneous cAMP levels, a major heterogeneity in cAMP/PKA signaling could be generated by the spatial distribution of the final terminators of this cascade, i.e., the phosphatases. Using FRET-based sensors to monitor cAMP and PKA-dependent phosphorylation in the cytosol and outer mitochondrial membrane (OMM) of primary rat cardiomyocytes, we demonstrate that comparable cAMP increases in these two compartments evoke higher levels of PKA-dependent phosphorylation in the OMM. This difference is most evident for small, physiological increases of cAMP levels and with both OMM-located probes and endogenous OMM proteins. We demonstrate that this disparity depends on differences in the rates of phosphatase-dependent dephosphorylation of PKA targets in the two compartments. Furthermore, we show that the activity of soluble phosphatases attenuates PKA-driven activation of the cAMP response element-binding protein while concurrently enhancing PKA-dependent mitochondrial elongation. We conclude that phosphatases can sculpt functionally distinct cAMP/PKA domains even in the absence of gradients or microdomains of this messenger. We present a model that accounts for these unexpected results in which the degree of PKA-dependent phosphorylation is dictated by both the subcellular distribution of the phosphatases and the different accessibility of membrane-bound and soluble phosphorylated substrates to the cytosolic enzymes.
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Monterisi S, Lobo MJ, Livie C, Castle JC, Weinberger M, Baillie G, Surdo NC, Musheshe N, Stangherlin A, Gottlieb E, Maizels R, Bortolozzi M, Micaroni M, Zaccolo M. PDE2A2 regulates mitochondria morphology and apoptotic cell death via local modulation of cAMP/PKA signalling. eLife 2017; 6:e21374. [PMID: 28463107 PMCID: PMC5423767 DOI: 10.7554/elife.21374] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 04/29/2017] [Indexed: 01/31/2023] Open
Abstract
cAMP/PKA signalling is compartmentalised with tight spatial and temporal control of signal propagation underpinning specificity of response. The cAMP-degrading enzymes, phosphodiesterases (PDEs), localise to specific subcellular domains within which they control local cAMP levels and are key regulators of signal compartmentalisation. Several components of the cAMP/PKA cascade are located to different mitochondrial sub-compartments, suggesting the presence of multiple cAMP/PKA signalling domains within the organelle. The function and regulation of these domains remain largely unknown. Here, we describe a novel cAMP/PKA signalling domain localised at mitochondrial membranes and regulated by PDE2A2. Using pharmacological and genetic approaches combined with real-time FRET imaging and high resolution microscopy, we demonstrate that in rat cardiac myocytes and other cell types mitochondrial PDE2A2 regulates local cAMP levels and PKA-dependent phosphorylation of Drp1. We further demonstrate that inhibition of PDE2A, by enhancing the hormone-dependent cAMP response locally, affects mitochondria dynamics and protects from apoptotic cell death.
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Affiliation(s)
- Stefania Monterisi
- Department of Physiology Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
- BHF Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Miguel J Lobo
- Department of Physiology Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
- BHF Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Craig Livie
- Institute of Neuroscioence and Psychology, University of Glasgow, Glasgow, United Kingdom
| | - John C Castle
- Department of Physiology Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
- BHF Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Michael Weinberger
- Department of Physiology Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
- BHF Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - George Baillie
- Institute of Cardiovascular and Medical Science, University of Glasgow, Glasgow, United Kingdom
| | - Nicoletta C Surdo
- Department of Physiology Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
- BHF Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Nshunge Musheshe
- Department of Molecular Pharmacology, University of Groningen, Groningen, The Netherlands
| | - Alessandra Stangherlin
- Institute of Neuroscioence and Psychology, University of Glasgow, Glasgow, United Kingdom
| | - Eyal Gottlieb
- Beatson Institute, University of Glasgow, Glasgow, United Kingdom
| | - Rory Maizels
- Department of Physiology Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
- BHF Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Mario Bortolozzi
- Department of Physics and Astronomy “G. Galilei”, University of Padova, Padova, Italy
- Venetian Institute of Molecular Medicine, University of Padova, Padova, Italy
| | - Massimo Micaroni
- Swedish National Centre for Cellular Imaging, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Manuela Zaccolo
- Department of Physiology Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
- BHF Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
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Abnormalities of Mitochondrial Dynamics in Neurodegenerative Diseases. Antioxidants (Basel) 2017; 6:antiox6020025. [PMID: 28379197 PMCID: PMC5488005 DOI: 10.3390/antiox6020025] [Citation(s) in RCA: 141] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 03/24/2017] [Accepted: 04/03/2017] [Indexed: 12/14/2022] Open
Abstract
Neurodegenerative diseases are incurable and devastating neurological disorders characterized by the progressive loss of the structure and function of neurons in the central nervous system or peripheral nervous system. Mitochondria, organelles found in most eukaryotic cells, are essential for neuronal survival and are involved in a number of neuronal functions. Mitochondrial dysfunction has long been demonstrated as a common prominent early pathological feature of a variety of common neurodegenerative diseases, including Alzheimer’s disease (AD), Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS), and Huntington’s disease (HD). Mitochondria are highly dynamic organelles that undergo continuous fusion, fission, and transport, the processes of which not only control mitochondrial morphology and number but also regulate mitochondrial function and location. The importance of mitochondrial dynamics in the pathogenesis of neurodegenerative diseases has been increasingly unraveled after the identification of several key fusion and fission regulators such as Drp1, OPA1, and mitofusins. In this review, after a brief discussion of molecular mechanisms regulating mitochondrial fusion, fission, distribution, and trafficking, as well as the important role of mitochondrial dynamics for neuronal function, we review previous and the most recent studies about mitochondrial dynamic abnormalities observed in various major neurodegenerative diseases and discuss the possibility of targeting mitochondrial dynamics as a likely novel therapeutic strategy for neurodegenerative diseases.
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Dominant optic atrophy: updates on the pathophysiology and clinical manifestations of the optic atrophy 1 mutation. Curr Opin Ophthalmol 2016; 27:475-480. [PMID: 27585216 DOI: 10.1097/icu.0000000000000314] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
PURPOSE OF REVIEW Review recent advances in clinical and experimental studies of dominant optic atrophy (DOA) to better understand the complexities of pathophysiology caused by the optic atrophy 1 (OPA1) mutation. RECENT FINDINGS DOA is the most commonly diagnosed inherited optic atrophy, causing progressive bilateral visual loss that begins early in life. During the past 25 years, there has been substantial progress in the understanding of the clinical, genetic, and pathophysiological basis of this disease. The histopathological hallmark of DOA is the primary degeneration of retinal ganglion cells, preferentially in the papillomacular bundle, which results temporal optic disc pallor and cecocentral scotomata in patients with DOA. Loss of OPA1 protein function by OPA1 gene mutations causes mitochondrial dysfunction because of the loss of mitochondrial fusion, impaired mitochondrial oxidative phosphorylation, increases in reactive oxygen species, and altered calcium homeostasis. These factors lead to apoptosis of retinal ganglion cells by a haploinsufficiency mechanism. SUMMARY Improved understanding of the pathophysiology of DOA provides insights that can be used to develop therapeutic approaches to the DOA.
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Kushnareva Y, Seong Y, Andreyev AY, Kuwana T, Kiosses WB, Votruba M, Newmeyer DD. Mitochondrial dysfunction in an Opa1(Q285STOP) mouse model of dominant optic atrophy results from Opa1 haploinsufficiency. Cell Death Dis 2016; 7:e2309. [PMID: 27468686 PMCID: PMC4973340 DOI: 10.1038/cddis.2016.160] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 04/29/2016] [Accepted: 05/02/2016] [Indexed: 12/22/2022]
Abstract
Mutations in the opa1 (optic atrophy 1) gene lead to autosomal dominant optic atrophy (ADOA), a hereditary eye disease. This gene encodes the Opa1 protein, a mitochondrial dynamin-related GTPase required for mitochondrial fusion and the maintenance of normal crista structure. The majority of opa1 mutations encode truncated forms of the protein, lacking a complete GTPase domain. It is unclear whether the phenotype results from haploinsufficiency or rather a deleterious effect of truncated Opa1 protein. We studied a heterozygous Opa1 mutant mouse carrying a defective allele with a stop codon in the beginning of the GTPase domain at residue 285, a mutation that mimics human pathological mutations. Using an antibody raised against an N-terminal portion of Opa1, we found that the level of wild-type protein was decreased in the mutant mice, as predicted. However, no truncated Opa1 protein was expressed. In embryonic fibroblasts isolated from the mutant mice, this partial loss of Opa1 caused mitochondrial respiratory deficiency and a selective loss of respiratory Complex IV subunits. Furthermore, partial Opa1 deficiency resulted in a substantial resistance to endoplasmic reticulum stress-induced death. On the other hand, the enforced expression of truncated Opa1 protein in cells containing normal levels of wild-type protein did not cause mitochondrial defects. Moreover, cells expressing the truncated Opa1 protein showed reduced Bax activation in response to apoptotic stimuli. Taken together, our results exclude deleterious dominant-negative or gain-of-function mechanisms for this type of Opa1 mutation and affirm haploinsufficiency as the mechanism underlying mitochondrial dysfunction in ADOA.
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Affiliation(s)
- Y Kushnareva
- Immune Regulation, La Jolla Institute for Allergy and Immunology, 9420 Athena Circle, La Jolla, CA 92037, USA
| | - Y Seong
- Immune Regulation, La Jolla Institute for Allergy and Immunology, 9420 Athena Circle, La Jolla, CA 92037, USA
| | - A Y Andreyev
- Department of Pharmacology, University of California San Diego, La Jolla, CA 92093, USA
| | - T Kuwana
- Immune Regulation, La Jolla Institute for Allergy and Immunology, 9420 Athena Circle, La Jolla, CA 92037, USA
| | - W B Kiosses
- Immune Regulation, La Jolla Institute for Allergy and Immunology, 9420 Athena Circle, La Jolla, CA 92037, USA
| | - M Votruba
- School of Optometry and Vision Sciences, Cardiff University, Cardiff CF24 4LU, UK.,Cardiff Eye Unit, University Hospital Wales, Cardiff CF14 4XW, UK
| | - D D Newmeyer
- Immune Regulation, La Jolla Institute for Allergy and Immunology, 9420 Athena Circle, La Jolla, CA 92037, USA
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Millet AMC, Bertholet AM, Daloyau M, Reynier P, Galinier A, Devin A, Wissinguer B, Belenguer P, Davezac N. Loss of functional OPA1 unbalances redox state: implications in dominant optic atrophy pathogenesis. Ann Clin Transl Neurol 2016; 3:408-21. [PMID: 27547769 PMCID: PMC4891995 DOI: 10.1002/acn3.305] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 03/04/2016] [Accepted: 03/05/2016] [Indexed: 12/14/2022] Open
Abstract
Objective OPA1 mutations cause protein haploinsufficiency leading to dominant optic atrophy (DOA), an incurable retinopathy with variable severity. Up to 20% of patients also develop extraocular neurological complications. The mechanisms that cause this optic atrophy or its syndromic forms are still unknown. After identifying oxidative stress in a mouse model of the pathology, we sought to determine the consequences of OPA1 dysfunction on redox homeostasis. Methods Mitochondrial respiration, reactive oxygen species levels, antioxidant defenses, and cell death were characterized by biochemical and in situ approaches in both in vitro and in vivo models of OPA1 haploinsufficiency. Results A decrease in aconitase activity suggesting an increase in reactive oxygene species and an induction of antioxidant defenses was observed in cortices of a murine model as well as in OPA1 downregulated cortical neurons. This increase is associated with a decline in mitochondrial respiration in vitro. Upon exogenous oxidative stress, OPA1‐depleted neurons did not further exhibit upregulated antioxidant defenses but were more sensitive to cell death. Finally, low levels of antioxidant enzymes were found in fibroblasts from patients supporting their role as modifier factors. Interpretation Our study suggests that the pro‐oxidative state induced by OPA1 loss may contribute to DOA pathogenesis and that differences in antioxidant defenses can explain the variability in expressivity. Furthermore, antioxidants may be used as therapy as they could prevent or delay DOA symptoms in patients.
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Affiliation(s)
- Aurélie M C Millet
- Center of Developmental Biology (CBD)/Research Center on Animal Cognition (CRCA) Center for Integrative Biology (CBI) Toulouse University, CNRS, UPS Toulouse France
| | - Ambre M Bertholet
- Center of Developmental Biology (CBD)/Research Center on Animal Cognition (CRCA) Center for Integrative Biology (CBI) Toulouse University, CNRS, UPS Toulouse France
| | - Marlène Daloyau
- Center of Developmental Biology (CBD)/Research Center on Animal Cognition (CRCA) Center for Integrative Biology (CBI) Toulouse University, CNRS, UPS Toulouse France
| | - Pascal Reynier
- CNRS UMR 6214 Inserm UMR 1083 UFR Sciences médicales Rue Haute de Reculee Angers Cedex 01 49045 France
| | - Anne Galinier
- Laboratoire de Biochimie Nutritionnelle "STROMALab" UMR UPS/CNRS/EFS 5273 Inserm U1031, CHU Rangueil 1 avenue Jean Poulhès Toulouse Cedex 9 31059 France
| | - Anne Devin
- Laboratoire métabolisme énergétique cellulaire IBGC du CNRS 1 rue Camille Saint Saëns Bordeaux Cedex 33077 France
| | - Bernd Wissinguer
- Centre for Ophthalmology University of Tübingen Roentgenweg 11 Tübingen D-72076 Germany
| | - Pascale Belenguer
- Center of Developmental Biology (CBD)/Research Center on Animal Cognition (CRCA) Center for Integrative Biology (CBI) Toulouse University, CNRS, UPS Toulouse France
| | - Noélie Davezac
- Center of Developmental Biology (CBD)/Research Center on Animal Cognition (CRCA) Center for Integrative Biology (CBI) Toulouse University, CNRS, UPS Toulouse France
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Cogliati S, Enriquez JA, Scorrano L. Mitochondrial Cristae: Where Beauty Meets Functionality. Trends Biochem Sci 2016; 41:261-273. [PMID: 26857402 DOI: 10.1016/j.tibs.2016.01.001] [Citation(s) in RCA: 508] [Impact Index Per Article: 63.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 01/07/2016] [Accepted: 01/08/2016] [Indexed: 01/30/2023]
Abstract
Mitochondrial cristae are dynamic bioenergetic compartments whose shape changes under different physiological conditions. Recent discoveries have unveiled the relation between cristae shape and oxidative phosphorylation (OXPHOS) function, suggesting that membrane morphology modulates the organization and function of the OXPHOS system, with a direct impact on cellular metabolism. As a corollary, cristae-shaping proteins have emerged as potential modulators of mitochondrial bioenergetics, a concept confirmed by genetic experiments in mouse models of respiratory chain deficiency. Here, we review our knowledge of mitochondrial ultrastructural organization and how it impacts mitochondrial metabolism.
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Affiliation(s)
- Sara Cogliati
- Centro Nacional de Investigaciònes Cardiovasculares Carlos III, Madrid, Spain
| | - Jose A Enriquez
- Centro Nacional de Investigaciònes Cardiovasculares Carlos III, Madrid, Spain; Departamento de Bioquímica, Universidad Zaragoza, Zaragoza, Spain
| | - Luca Scorrano
- Dulbecco Telethon Institute, Venetian Institute of Molecular Medicine, Padova, Italy; Department of Biology, University of Padova, Padova, Italy.
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30
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Inner membrane fusion mediates spatial distribution of axonal mitochondria. Sci Rep 2016; 6:18981. [PMID: 26742817 PMCID: PMC4705540 DOI: 10.1038/srep18981] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 12/01/2015] [Indexed: 12/15/2022] Open
Abstract
In eukaryotic cells, mitochondria form a dynamic interconnected network to respond to changing needs at different subcellular locations. A fundamental yet unanswered question regarding this network is whether, and if so how, local fusion and fission of individual mitochondria affect their global distribution. To address this question, we developed high-resolution computational image analysis techniques to examine the relations between mitochondrial fusion/fission and spatial distribution within the axon of Drosophila larval neurons. We found that stationary and moving mitochondria underwent fusion and fission regularly but followed different spatial distribution patterns and exhibited different morphology. Disruption of inner membrane fusion by knockdown of dOpa1, Drosophila Optic Atrophy 1, not only increased the spatial density of stationary and moving mitochondria but also changed their spatial distributions and morphology differentially. Knockdown of dOpa1 also impaired axonal transport of mitochondria. But the changed spatial distributions of mitochondria resulted primarily from disruption of inner membrane fusion because knockdown of Milton, a mitochondrial kinesin-1 adapter, caused similar transport velocity impairment but different spatial distributions. Together, our data reveals that stationary mitochondria within the axon interconnect with moving mitochondria through fusion and fission and that local inner membrane fusion between individual mitochondria mediates their global distribution.
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31
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Deng J, Yang M, Chen Y, Chen X, Liu J, Sun S, Cheng H, Li Y, Bigio EH, Mesulam M, Xu Q, Du S, Fushimi K, Zhu L, Wu JY. FUS Interacts with HSP60 to Promote Mitochondrial Damage. PLoS Genet 2015; 11:e1005357. [PMID: 26335776 PMCID: PMC4559378 DOI: 10.1371/journal.pgen.1005357] [Citation(s) in RCA: 129] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 06/12/2015] [Indexed: 12/13/2022] Open
Abstract
FUS-proteinopathies, a group of heterogeneous disorders including ALS-FUS and FTLD-FUS, are characterized by the formation of inclusion bodies containing the nuclear protein FUS in the affected patients. However, the underlying molecular and cellular defects remain unclear. Here we provide evidence for mitochondrial localization of FUS and its induction of mitochondrial damage. Remarkably, FTLD-FUS brain samples show increased FUS expression and mitochondrial defects. Biochemical and genetic data demonstrate that FUS interacts with a mitochondrial chaperonin, HSP60, and that FUS translocation to mitochondria is, at least in part, mediated by HSP60. Down-regulating HSP60 reduces mitochondrially localized FUS and partially rescues mitochondrial defects and neurodegenerative phenotypes caused by FUS expression in transgenic flies. This is the first report of direct mitochondrial targeting by a nuclear protein associated with neurodegeneration, suggesting that mitochondrial impairment may represent a critical event in different forms of FUS-proteinopathies and a common pathological feature for both ALS-FUS and FTLD-FUS. Our study offers a potential explanation for the highly heterogeneous nature and complex genetic presentation of different forms of FUS-proteinopathies. Our data also suggest that mitochondrial damage may be a target in future development of diagnostic and therapeutic tools for FUS-proteinopathies, a group of devastating neurodegenerative diseases. Amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) are two groups of common and devastating neurodegenerative diseases, characterized by losses of selected groups of neurons. Mutations in the FUS gene have been associated with ALS, whereas inclusion bodies containing the FUS protein have been discovered in both ALS and FTLD patients. However, the underlying pathogenic mechanisms of FUS in these diseases remain unclear. Here, we demonstrate that wild-type or ALS-associated mutant FUS can interact with mitochondrial chaperonin HSP60 and that HSP60 mediates FUS localization to mitochondria, leading to mitochondrial damage. Mitochondrial impairment may be an early event in FUS proteinopathies and represent a potential therapeutic target for treating these fatal diseases.
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Affiliation(s)
- Jianwen Deng
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Mengxue Yang
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
- Department of Neurology, Center for Genetic Medicine, Lurie Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Yanbo Chen
- Department of Neurology, Center for Genetic Medicine, Lurie Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Science and Peking Union Medical College, Tsinghua University, Beijing, China
| | - Xiaoping Chen
- Department of Neurology, Center for Genetic Medicine, Lurie Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Jianghong Liu
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Shufeng Sun
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Haipeng Cheng
- Department of Neurology, Center for Genetic Medicine, Lurie Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Yang Li
- Department of Neurology, Center for Genetic Medicine, Lurie Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- School of Electronic Science and Engineering, Nanjing University, Nanjing, China
| | - Eileen H. Bigio
- Department of Pathology & Neurology, The Cognitive Neurology& Alzheimer's Disease Center, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Marsel Mesulam
- Department of Pathology & Neurology, The Cognitive Neurology& Alzheimer's Disease Center, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Qi Xu
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Science and Peking Union Medical College, Tsinghua University, Beijing, China
| | - Sidan Du
- School of Electronic Science and Engineering, Nanjing University, Nanjing, China
| | - Kazuo Fushimi
- Department of Neurology, Center for Genetic Medicine, Lurie Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Li Zhu
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- * E-mail: (LZ); (JYW)
| | - Jane Y. Wu
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- Department of Neurology, Center for Genetic Medicine, Lurie Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- * E-mail: (LZ); (JYW)
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32
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Sládková J, Spáčilová J, Čapek M, Tesařová M, Hansíková H, Honzík T, Martínek J, Zámečník J, Kostková O, Zeman J. Analysis of Mitochondrial Network Morphology in Cultured Myoblasts from Patients with Mitochondrial Disorders. Ultrastruct Pathol 2015. [DOI: 10.3109/01913123.2015.1054013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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33
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Formichi P, Radi E, Giorgi E, Gallus GN, Brunetti J, Battisti C, Rufa A, Dotti MT, Franceschini R, Bracci L, Federico A. Analysis of opa1 isoforms expression and apoptosis regulation in autosomal dominant optic atrophy (ADOA) patients with mutations in the opa1 gene. J Neurol Sci 2015; 351:99-108. [DOI: 10.1016/j.jns.2015.02.047] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 02/26/2015] [Accepted: 02/27/2015] [Indexed: 11/29/2022]
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Lassiter K, Greene E, Piekarski A, Faulkner OB, Hargis BM, Bottje W, Dridi S. Orexin system is expressed in avian muscle cells and regulates mitochondrial dynamics. Am J Physiol Regul Integr Comp Physiol 2014; 308:R173-87. [PMID: 25502749 DOI: 10.1152/ajpregu.00394.2014] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Orexin A and B, orexigenic peptides produced primarily by the lateral hypothalamus that signal through two G protein-coupled receptors, orexin receptors 1/2, have been implicated in the regulation of several physiological processes in mammals. In avian (nonmammalian vertebrates) species; however, the physiological roles of orexin are not well defined. Here, we provide novel evidence that not only is orexin and its related receptors 1/2 (ORXR1/2) expressed in chicken muscle tissue and quail muscle (QM7) cell line, orexin appears to be a secretory protein in QM7 cells. In vitro administration of recombinant orexin A and B (rORX-A and B) differentially regulated prepro-orexin expression in a dose-dependent manner with up-regulation for rORX-A (P < 0.05) and downregulation for rORX-B (P < 0.05) in QM7 cells. While both peptides upregulated ORXR1 expression, only a high dose of rORX-B decreased the expression of ORXR2 (P < 0.05). The presence of orexin and its related receptors and the regulation of its own system in avian muscle cells indicate that orexin may have autocrine, paracrine, and/or endocrine roles. rORXs differentially regulated mitochondrial dynamics network. While rORX-A significantly induced the expression of mitochondrial fission-related genes (DNM1, MTFP1, MTFR1), rORX-B increased the expression of mitofusin 2, OPA1, and OMA1 genes that are involved in mitochondrial fusion. Concomitant with these changes, rORXs differentially regulated the expression of several mitochondrial metabolic genes (av-UCP, av-ANT, Ski, and NRF-1) and their related transcriptional regulators (PPARγ, PPARα, PGC-1α, PGC-1β, and FoxO-1) without affecting ATP synthesis. Taken together, our data represent the first evidence of the presence and secretion of orexin system in the muscle of nonmammalian species and its role in mitochondrial fusion and fission, probably through mitochondrial-related genes and their related transcription factors.
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Affiliation(s)
- Kentu Lassiter
- Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, Arkansas
| | - Elizabeth Greene
- Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, Arkansas
| | - Alissa Piekarski
- Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, Arkansas
| | - Olivia B Faulkner
- Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, Arkansas
| | - Billy M Hargis
- Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, Arkansas
| | - Walter Bottje
- Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, Arkansas
| | - Sami Dridi
- Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, Arkansas
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36
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Wang X, Li H, Zheng A, Yang L, Liu J, Chen C, Tang Y, Zou X, Li Y, Long J, Liu J, Zhang Y, Feng Z. Mitochondrial dysfunction-associated OPA1 cleavage contributes to muscle degeneration: preventative effect of hydroxytyrosol acetate. Cell Death Dis 2014; 5:e1521. [PMID: 25393477 PMCID: PMC4260731 DOI: 10.1038/cddis.2014.473] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 08/27/2014] [Accepted: 10/06/2014] [Indexed: 01/15/2023]
Abstract
Mitochondrial dysfunction contributes to the development of muscle disorders, including muscle wasting, muscle atrophy and degeneration. Despite the knowledge that oxidative stress closely interacts with mitochondrial dysfunction, the detailed mechanisms remain obscure. In this study, tert-butylhydroperoxide (t-BHP) was used to induce oxidative stress on differentiated C2C12 myotubes. t-BHP induced significant mitochondrial dysfunction in a time-dependent manner, accompanied by decreased myosin heavy chain (MyHC) expression at both the mRNA and protein levels. Consistently, endogenous reactive oxygen species (ROS) overproduction triggered by carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP), a mitochondrial oxidative phosphorylation inhibitor, was accompanied by decreased membrane potential and decreased MyHC protein content. However, the free radical scavenger N-acetyl-L-cysteine (NAC) efficiently reduced the ROS level and restored MyHC content, suggesting a close association between ROS and MyHC expression. Meanwhile, we found that both t-BHP and FCCP promoted the cleavage of optic atrophy 1 (OPA1) from the long form into short form during the early stages. In addition, the ATPase family gene 3-like 2, a mitochondrial inner membrane protease, was also markedly increased. Moreover, OPA1 knockdown in myotubes was accompanied by decreased MyHC content, whereas NAC failed to prevent FCCP-induced MyHC decrease with OPA1 knockdown, suggesting that ROS might affect MyHC content by modulating OPA1 cleavage. In addition, hydroxytyrosol acetate (HT-AC), an important compound in virgin olive oil, could significantly prevent t-BHP-induced mitochondrial membrane potential and cell viability loss in myotubes. Specifically, HT-AC inhibited t-BHP-induced OPA1 cleavage and mitochondrial morphology changes, accompanied by improvement on mitochondrial oxygen consumption capacity, ATP productive potential and activities of mitochondrial complex I, II and V. Moreover, both t-BHP- and FCCP-induced MyHC decrease was sufficiently inhibited by HT-AC. Taken together, our data provide evidence indicating that mitochondrial dysfunction-associated OPA1 cleavage may contribute to muscle degeneration, and olive oil compounds could be effective nutrients for preventing the development of muscle disorders.
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Affiliation(s)
- X Wang
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology and Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - H Li
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology and Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - A Zheng
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology and Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - L Yang
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology and Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - J Liu
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology and Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - C Chen
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology and Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - Y Tang
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology and Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - X Zou
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology and Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - Y Li
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology and Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - J Long
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology and Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - J Liu
- 1] Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology and Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, China [2] Tianjin Key Laboratory of Exercise Physiology & Sports Medicine, Tianjin University of Sport, Tianjin 300381, China
| | - Y Zhang
- Tianjin Key Laboratory of Exercise Physiology & Sports Medicine, Tianjin University of Sport, Tianjin 300381, China
| | - Z Feng
- Center for Mitochondrial Biology and Medicine, The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology and Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, China
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Abstract
Mitochondria are highly specialized in function, but mitochondrial and, therefore, cellular integrity is maintained through their dynamic nature. Through the frequent processes of fusion and fission, mitochondria continuously change in shape and adjust function to meet cellular requirements. Abnormalities in fusion/fission dynamics generate cellular dysfunction that may lead to diseases. Mutations in the genes encoding mitochondrial fusion/fission proteins, such as MFN2 and OPA1, have been associated with an increasing number of genetic disorders, including Charcot-Marie-Tooth disease type 2A (CMT2A) and autosomal dominant optic atrophy. In this review, we address the mitochondrial dynamic changes in several important genetic diseases, which will bring the new insight of clinical relevance of mitochondrial genetics.
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Affiliation(s)
- Le Chen
- Molecular & Cellular Cardiology, University of California, Davis, One Shields Avenue Davis, CA, 95616, USA,
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High-dialysate-glucose-induced oxidative stress and mitochondrial-mediated apoptosis in human peritoneal mesothelial cells. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2014; 2014:642793. [PMID: 24891925 PMCID: PMC4026970 DOI: 10.1155/2014/642793] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Revised: 03/30/2014] [Accepted: 04/01/2014] [Indexed: 11/23/2022]
Abstract
Human peritoneal mesothelial cells (HPMCs) are a critical component of the peritoneal membrane and play a pivotal role in dialysis adequacy. Loss of HPMCs can contribute to complications in peritoneal dialysis. Compelling evidence has shown that high-dialysate glucose is a key factor causing functional changes and cell death in HPMCs. We investigated the mechanism of HPMC apoptosis induced by high-dialysate glucose, particularly the role of mitochondria in the maintenance of HPMCs. HPMCs were incubated at glucose concentrations of 5 mM, 84 mM, 138 mM, and 236 mM. Additionally, N-acetylcysteine (NAC) was used as an antioxidant to clarify the mechanism of high-dialysate-glucose-induced apoptosis. Exposing HPMCs to high-dialysate glucose resulted in substantial apoptosis with cytochrome c release, followed by caspase activation and poly(ADP-ribose) polymerase cleavage. High-dialysate glucose induced excessive reactive oxygen species production and lipid peroxidation as well as oxidative damage to DNA. Mitochondrial fragmentation, multiple mitochondrial DNA deletions, and dissipation of the mitochondrial membrane potential were also observed. The mitochondrial dysfunction and cell death were suppressed using NAC. These results indicated that mitochondrial dysfunction is one of the main causes of high-dialysate-glucose-induced HPMC apoptosis.
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Ambrose LJA, Abd-Jamil AH, Gomes RSM, Carter EE, Carr CA, Clarke K, Heather LC. Investigating mitochondrial metabolism in contracting HL-1 cardiomyocytes following hypoxia and pharmacological HIF activation identifies HIF-dependent and independent mechanisms of regulation. J Cardiovasc Pharmacol Ther 2014; 19:574-85. [PMID: 24607765 DOI: 10.1177/1074248414524480] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Hypoxia is a consequence of cardiac disease and downregulates mitochondrial metabolism, yet the molecular mechanisms through which this occurs in the heart are incompletely characterized. Therefore, we aimed to use a contracting HL-1 cardiomyocyte model to investigate the effects of hypoxia on mitochondrial metabolism. Cells were exposed to hypoxia (2% O2) for 6, 12, 24, and 48 hours to characterize the metabolic response. Cells were subsequently treated with the hypoxia inducible factor (HIF)-activating compound, dimethyloxalylglycine (DMOG), to determine whether hypoxia-induced mitochondrial changes were HIF dependent or independent, and to assess the suitability of this cultured cardiac cell line for cardiovascular pharmacological studies. Hypoxic cells had increased glycolysis after 24 hours, with glucose transporter 1 and lactate levels increased 5-fold and 15-fold, respectively. After 24 hours of hypoxia, mitochondrial networks were more fragmented but there was no change in citrate synthase activity, indicating that mitochondrial content was unchanged. Cellular oxygen consumption was 30% lower, accompanied by decreases in the enzymatic activities of electron transport chain (ETC) complexes I and IV, and aconitase by 81%, 96%, and 72%, relative to controls. Pharmacological HIF activation with DMOG decreased cellular oxygen consumption by 43%, coincident with decreases in the activities of aconitase and complex I by 26% and 30%, indicating that these adaptations were HIF mediated. In contrast, the hypoxia-mediated decrease in complex IV activity was not replicated by DMOG treatment, suggesting HIF-independent regulation of this complex. In conclusion, 24 hours of hypoxia increased anaerobic glycolysis and decreased mitochondrial respiration, which was associated with changes in ETC and tricarboxylic acid cycle enzyme activities in contracting HL-1 cells. Pharmacological HIF activation in this cardiac cell line allowed both HIF-dependent and independent mitochondrial metabolic changes to be identified.
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Affiliation(s)
- Lucy J A Ambrose
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, England, United Kingdom
| | - Amira H Abd-Jamil
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, England, United Kingdom
| | - Renata S M Gomes
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, England, United Kingdom
| | - Emma E Carter
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, England, United Kingdom
| | - Carolyn A Carr
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, England, United Kingdom
| | - Kieran Clarke
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, England, United Kingdom
| | - Lisa C Heather
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, England, United Kingdom
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Alavi MV, Fuhrmann N. Dominant optic atrophy, OPA1, and mitochondrial quality control: understanding mitochondrial network dynamics. Mol Neurodegener 2013; 8:32. [PMID: 24067127 PMCID: PMC3856479 DOI: 10.1186/1750-1326-8-32] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 09/16/2013] [Indexed: 12/13/2022] Open
Abstract
Mitochondrial quality control is fundamental to all neurodegenerative diseases, including the most prominent ones, Alzheimer’s Disease and Parkinsonism. It is accomplished by mitochondrial network dynamics – continuous fission and fusion of mitochondria. Mitochondrial fission is facilitated by DRP1, while MFN1 and MFN2 on the mitochondrial outer membrane and OPA1 on the mitochondrial inner membrane are essential for mitochondrial fusion. Mitochondrial network dynamics are regulated in highly sophisticated ways by various different posttranslational modifications, such as phosphorylation, ubiquitination, and proteolytic processing of their key-proteins. By this, mitochondria process a wide range of different intracellular and extracellular parameters in order to adapt mitochondrial function to actual energetic and metabolic demands of the host cell, attenuate mitochondrial damage, recycle dysfunctional mitochondria via the mitochondrial autophagy pathway, or arrange for the recycling of the complete host cell by apoptosis. Most of the genes coding for proteins involved in this process have been associated with neurodegenerative diseases. Mutations in one of these genes are associated with a neurodegenerative disease that originally was described to affect retinal ganglion cells only. Since more and more evidence shows that other cell types are affected as well, we would like to discuss the pathology of dominant optic atrophy, which is caused by heterozygous sequence variants in OPA1, in the light of the current view on OPA1 protein function in mitochondrial quality control, in particular on its function in mitochondrial fusion and cytochrome C release. We think OPA1 is a good example to understand the molecular basis for mitochondrial network dynamics.
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Affiliation(s)
- Marcel V Alavi
- Department of Ophthalmology, University of California, San Francisco, 10 Koret Way, 94143-0730 San Francisco, CA, USA.
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Maresca A, la Morgia C, Caporali L, Valentino ML, Carelli V. The optic nerve: a "mito-window" on mitochondrial neurodegeneration. Mol Cell Neurosci 2013; 55:62-76. [PMID: 22960139 PMCID: PMC3629569 DOI: 10.1016/j.mcn.2012.08.004] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Revised: 07/27/2012] [Accepted: 08/06/2012] [Indexed: 01/16/2023] Open
Abstract
Retinal ganglion cells (RGCs) project their long axons, composing the optic nerve, to the brain, transmitting the visual information gathered by the retina, ultimately leading to formed vision in the visual cortex. The RGC cellular system, representing the anterior part of the visual pathway, is vulnerable to mitochondrial dysfunction and optic atrophy is a very frequent feature of mitochondrial and neurodegenerative diseases. The start of the molecular era of mitochondrial medicine, the year 1988, was marked by the identification of a maternally inherited form of optic atrophy, Leber's hereditary optic neuropathy, as the first disease due to mitochondrial DNA point mutations. The field of mitochondrial medicine has expanded enormously over the last two decades and many neurodegenerative diseases are now known to have a primary mitochondrial etiology or mitochondrial dysfunction plays a relevant role in their pathogenic mechanism. Recent technical advancements in neuro-ophthalmology, such as optical coherence tomography, prompted a still ongoing systematic re-investigation of retinal and optic nerve involvement in neurodegenerative disorders. In addition to inherited optic neuropathies, such as Leber's hereditary optic neuropathy and dominant optic atrophy, and in addition to the syndromic mitochondrial encephalomyopathies or mitochondrial neurodegenerative disorders such as some spinocerebellar ataxias or familial spastic paraparesis and other disorders, we draw attention to the involvement of the optic nerve in classic age-related neurodegenerative disorders such as Parkinson and Alzheimer disease. We here provide an overview of optic nerve pathology in these different clinical settings, and we review the possible mechanisms involved in the pathogenesis of optic atrophy. This may be a model of general value for the field of neurodegeneration. This article is part of a Special Issue entitled 'Mitochondrial function and dysfunction in neurodegeneration'.
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Affiliation(s)
| | | | | | | | - Valerio Carelli
- Corresponding author at: IRCCS Institute of Neurological Sciences of Bologna, Department of Neurological Sciences, University of Bologna, Via Ugo Foscolo 7, 40123 Bologna, Italy. Fax: + 39 051 2092751.
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Liskova P, Ulmanova O, Tesina P, Melsova H, Diblik P, Hansikova H, Tesarova M, Votruba M. Novel OPA1 missense mutation in a family with optic atrophy and severe widespread neurological disorder. Acta Ophthalmol 2013; 91:e225-31. [PMID: 23387428 DOI: 10.1111/aos.12038] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE To identify the underlying molecular genetic cause in a Czech family with optic atrophy, deafness, ptosis, ophthalmoplegia, polyneuropathy and ataxia transmitted as an autosomal dominant trait. METHODS Ophthalmological and neurological examination followed by molecular genetic analyses. RESULTS Seven family members were clinically affected. There was a variable but progressive visual, hearing and neurological disability across the family as a whole. The majority of subjects presented with impairment of visual function and a variable degree of ptosis and/or ophthalmoplegia from the first to the third decade of life. Deafness, neuropathy and ataxia appeared later, in the third and fourth decade. Migraine, tachycardia, intention tremor, nystagmus and cervical dystonia were observed in isolated individuals. A significant overall feature was the high level of neurological disability leading to 3 of 4 members being unable to walk or stand unaided before the age of 60 years. A novel missense mutation c.1345A>C (p.Thr449Pro) in OPA1 segregating with the disease phenotype over three generations was detected. In silico analysis supported pathogenicity of the identified sequence variant. CONCLUSION Our work expands the spectrum of mutation in OPA1, which may lead to severe multisystem neurological disorder. The molecular genetic cause of dominant optic atrophy in the Czech population is reported for the first time. We propose that regular cardiac follow-up in patients diagnosed with dominant optic atrophy and widespread neurological disease should be considered.
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Affiliation(s)
- Petra Liskova
- Laboratory of the Biology and Pathology of the Eye, Institute of Inherited Metabolic Disorders, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Prague, Czech Republic
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Belenguer P, Pellegrini L. The dynamin GTPase OPA1: More than mitochondria? BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:176-83. [DOI: 10.1016/j.bbamcr.2012.08.004] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 08/01/2012] [Accepted: 08/03/2012] [Indexed: 12/24/2022]
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Yang RF, Zhao GW, Liang ST, Zhang Y, Sun LH, Chen HZ, Liu DP. Mitofilin regulates cytochrome c release during apoptosis by controlling mitochondrial cristae remodeling. Biochem Biophys Res Commun 2012; 428:93-8. [PMID: 23058921 DOI: 10.1016/j.bbrc.2012.10.012] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Accepted: 10/02/2012] [Indexed: 12/26/2022]
Abstract
Mitochondria amplify caspase-dependent apoptosis by releasing proapoptotic proteins, especially cytochrome c. This process is accompanied by mitochondrial cristae remodeling. Our studies demonstrated that mitofilin, a mitochondrial inner membrane protein, acted as a cristae controller to regulate cytochrome c release during apoptosis. Knockdown of mitofilin in HeLa cells with RNAi led to fragmentation of the mitochondrial network and disorganization of the cristae. Mitofilin-deficient cells showed cytochrome c redistribution between mitochondrial cristae and the intermembrane space (IMS) upon intrinsic apoptotic stimuli. In vitro cytochrome c release experiments further confirmed that, compared with the control group, tBid treatment led to an increase in cytochrome c release from mitofilin-deficient mitochondria. Furthermore, the cells with mitofilin knockdown were more prone to apoptosis by accelerating cytochrome c release upon the intrinsic apoptotic stimuli than controls. Moreover, mitofilin deficiency did not interfere with the activation of proapoptotic member Bax upon intrinsic apoptotic stimuli. Thus, mitofilin distinctly functions in cristae remodeling and controls cytochrome c release during apoptosis.
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Affiliation(s)
- Rui-Feng Yang
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences (CAMS) and Peking Union Medical College (PUMC), 5 Dong Dan San Tiao, Beijing 100005, PR China
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Agier V, Oliviero P, Lainé J, L'Hermitte-Stead C, Girard S, Fillaut S, Jardel C, Bouillaud F, Bulteau AL, Lombès A. Defective mitochondrial fusion, altered respiratory function, and distorted cristae structure in skin fibroblasts with heterozygous OPA1 mutations. Biochim Biophys Acta Mol Basis Dis 2012; 1822:1570-80. [PMID: 22800932 DOI: 10.1016/j.bbadis.2012.07.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Revised: 07/04/2012] [Accepted: 07/09/2012] [Indexed: 11/16/2022]
Abstract
Deleterious consequences of heterozygous OPA1 mutations responsible for autosomal dominant optic atrophy remain a matter of debate. Primary skin fibroblasts derived from patients have shown diverse mitochondrial alterations that were however difficult to resolve in a unifying scheme. To address the potential use of these cells as disease model, we undertook parallel and quantitative analyses of the diverse reported alterations in four fibroblast lines harboring different OPA1 mutations, nonsense or missense, in the guanosine triphosphatase or the C-terminal coiled-coil domains. We tackled several factors potentially underlying discordant reports and showed that fibroblasts with heterozygous OPA1 mutations present with several mitochondrial alterations. These included defective mitochondrial fusion during pharmacological challenge with the protonophore carbonyl cyanide m-chlorophenyl hydrazone, significant mitochondrial elongation with decreased OPA1 and DRP1 proteins, and abnormal mitochondrial fragmentation during glycolysis shortage or exogenous oxidative stress. Respiratory complex IV activity and subunits steady-state were decreased without alteration of the mitochondrial deoxyribonucleic acid size, amount or transcription. Physical link between OPA1 protein and oxidative phosphorylation was shown by reciprocal immunoprecipitation. Altered cristae structure coexisted with normal response to pro-apoptotic stimuli and expression of Bax or Bcl2 proteins. Skin fibroblasts with heterozygous OPA1 mutations thus share significant mitochondrial remodeling, and may therefore be useful for analyzing disease pathophysiology. Identifying whether the observed alterations are also present in ganglion retinal cells, and which of them underlies their degeneration process remains however an essential goal for therapeutic strategy.
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Affiliation(s)
- Virginie Agier
- Centre de Recherche de l'Institut du Cerveau et de la Moëlle, Inserm UMRS 975, Paris, France
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Lenaers G, Hamel C, Delettre C, Amati-Bonneau P, Procaccio V, Bonneau D, Reynier P, Milea D. Dominant optic atrophy. Orphanet J Rare Dis 2012; 7:46. [PMID: 22776096 PMCID: PMC3526509 DOI: 10.1186/1750-1172-7-46] [Citation(s) in RCA: 171] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Accepted: 03/15/2012] [Indexed: 11/18/2022] Open
Abstract
Definition of the disease Dominant Optic Atrophy (DOA) is a neuro-ophthalmic condition characterized by a bilateral degeneration of the optic nerves, causing insidious visual loss, typically starting during the first decade of life. The disease affects primary the retinal ganglion cells (RGC) and their axons forming the optic nerve, which transfer the visual information from the photoreceptors to the lateral geniculus in the brain. Epidemiology The prevalence of the disease varies from 1/10000 in Denmark due to a founder effect, to 1/30000 in the rest of the world. Clinical description DOA patients usually suffer of moderate visual loss, associated with central or paracentral visual field deficits and color vision defects. The severity of the disease is highly variable, the visual acuity ranging from normal to legal blindness. The ophthalmic examination discloses on fundoscopy isolated optic disc pallor or atrophy, related to the RGC death. About 20% of DOA patients harbour extraocular multi-systemic features, including neurosensory hearing loss, or less commonly chronic progressive external ophthalmoplegia, myopathy, peripheral neuropathy, multiple sclerosis-like illness, spastic paraplegia or cataracts. Aetiology Two genes (OPA1, OPA3) encoding inner mitochondrial membrane proteins and three loci (OPA4, OPA5, OPA8) are currently known for DOA. Additional loci and genes (OPA2, OPA6 and OPA7) are responsible for X-linked or recessive optic atrophy. All OPA genes yet identified encode mitochondrial proteins embedded in the inner membrane and ubiquitously expressed, as are the proteins mutated in the Leber Hereditary Optic Neuropathy. OPA1 mutations affect mitochondrial fusion, energy metabolism, control of apoptosis, calcium clearance and maintenance of mitochondrial genome integrity. OPA3 mutations only affect the energy metabolism and the control of apoptosis. Diagnosis Patients are usually diagnosed during their early childhood, because of bilateral, mild, otherwise unexplained visual loss related to optic discs pallor or atrophy, and typically occurring in the context of a family history of DOA. Optical Coherence Tomography further discloses non-specific thinning of retinal nerve fiber layer, but a normal morphology of the photoreceptors layers. Abnormal visual evoked potentials and pattern ERG may also reflect the dysfunction of the RGCs and their axons. Molecular diagnosis is provided by the identification of a mutation in the OPA1 gene (75% of DOA patients) or in the OPA3 gene (1% of patients). Prognosis Visual loss in DOA may progress during puberty until adulthood, with very slow subsequent chronic progression in most of the cases. On the opposite, in DOA patients with associated extra-ocular features, the visual loss may be more severe over time. Management To date, there is no preventative or curative treatment in DOA; severely visually impaired patients may benefit from low vision aids. Genetic counseling is commonly offered and patients are advised to avoid alcohol and tobacco consumption, as well as the use of medications that may interfere with mitochondrial metabolism. Gene and pharmacological therapies for DOA are currently under investigation.
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Affiliation(s)
- Guy Lenaers
- Institut des Neurosciences de Montpellier, U1051 de l'INSERM, Université de Montpellier I et II, BP 74103, F-34091 Montpellier cedex 05, France.
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Mitochondrial dynamics in cancer and neurodegenerative and neuroinflammatory diseases. Int J Cell Biol 2012; 2012:729290. [PMID: 22792111 PMCID: PMC3391904 DOI: 10.1155/2012/729290] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Accepted: 04/12/2012] [Indexed: 11/18/2022] Open
Abstract
Mitochondria are key organelles in the cell, hosting essential functions, from biosynthetic and metabolic pathways, to oxidative phosphorylation and ATP production, from calcium buffering to red-ox homeostasis and apoptotic signalling pathways. Mitochondria are also dynamic organelles, continuously fusing and dividing, and their localization, size and trafficking are finely regulated. Moreover, in recent decades, alterations in mitochondrial function and dynamics have been implicated in an increasing number of diseases. In this review, we focus on the relationship clarified hitherto between mitochondrial dynamics and cancer, neurodegenerative and neuroinflammatory diseases.
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Sgarbi G, Giannone F, Casalena GA, Baracca A, Baldassare M, Longobardi P, Caraceni P, Derenzini M, Lenaz G, Trerè D, Solaini G. Hyperoxia fully protects mitochondria of explanted livers. J Bioenerg Biomembr 2011; 43:673-82. [PMID: 22015484 DOI: 10.1007/s10863-011-9390-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2011] [Accepted: 09/28/2011] [Indexed: 12/18/2022]
Abstract
Liver ischemia-reperfusion injury is still an open problem in many clinical circumstances, including surgery and transplantation. This study investigates how mitochondrial structure, mass and oxidative phosphorylation change and may be preserved during a brief period of ischemia followed by a long period of reperfusion, an experimental model that mimics the condition to which a liver is exposed during transplantation. Livers were explanted from rats and exposed for 24 h to three different oxygen availability conditions at 4 °C. Mitochondrial mass, respiration, oxidative phosphorylation (OXPHOS), and levels of OXPHOS complexes were all significantly altered in livers stored under the currently used preservation condition of normoxia. Remarkably, liver perfusion with hyperoxic solutions fully preserved mitochondrial morphology and function, suggesting that perfusion of the graft with hyperoxic solution should be considered in human transplantation.
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Affiliation(s)
- G Sgarbi
- Department of Biochemistry, University of Bologna, Via Irnerio, 48, 40126, Bologna, Italy
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Pidoux G, Witczak O, Jarnæss E, Myrvold L, Urlaub H, Stokka AJ, Küntziger T, Taskén K. Optic atrophy 1 is an A-kinase anchoring protein on lipid droplets that mediates adrenergic control of lipolysis. EMBO J 2011; 30:4371-86. [PMID: 21983901 DOI: 10.1038/emboj.2011.365] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2011] [Accepted: 09/07/2011] [Indexed: 12/16/2022] Open
Abstract
Adrenergic stimulation of adipocytes yields a cAMP signal that activates protein kinase A (PKA). PKA phosphorylates perilipin, a protein localized on the surface of lipid droplets that serves as a gatekeeper to regulate access of lipases converting stored triglycerides to free fatty acids and glycerol in a phosphorylation-dependent manner. Here, we report a new function for optic atrophy 1 (OPA1), a protein known to regulate mitochondrial dynamics, as a dual-specificity A-kinase anchoring protein associated with lipid droplets. By a variety of protein interaction assays, immunoprecipitation and immunolocalization experiments, we show that OPA1 organizes a supramolecular complex containing both PKA and perilipin. Furthermore, by a combination of siRNA-mediated knockdown, reconstitution experiments using full-length OPA1 with or without the ability to bind PKA or truncated OPA1 fused to a lipid droplet targeting domain and cellular delivery of PKA anchoring disruptor peptides, we demonstrate that OPA1 targeting of PKA to lipid droplets is necessary for hormonal control of perilipin phosphorylation and lipolysis.
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Affiliation(s)
- Guillaume Pidoux
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, Oslo, Norway
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Schaaf CP, Blazo M, Lewis RA, Tonini RE, Takei H, Wang J, Wong LJ, Scaglia F. Early-onset severe neuromuscular phenotype associated with compound heterozygosity for OPA1 mutations. Mol Genet Metab 2011; 103:383-7. [PMID: 21636302 DOI: 10.1016/j.ymgme.2011.04.018] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Revised: 04/29/2011] [Accepted: 04/30/2011] [Indexed: 01/21/2023]
Abstract
INTRODUCTION Pathogenic mutations in the OPA1 gene are the most common identifiable cause of autosomal dominant optic atrophy (DOA), which is characterized by selective retinal ganglion cell loss, a distinctive pattern of temporal pallor of the optic nerve and a typical color vision deficit, with variable effects on visual acuity. Haploinsufficiency has been suggested as the major pathogenic mechanism for DOA. Here we present two siblings with severe ataxia, hypotonia, gastrointestinal dysmotility, dysphagia, and severe, early-onset optic atrophy who were found to be compound heterozygotes for two pathogenic OPA1 mutations. This example expands the clinical phenotype of OPA1-associated disorders and provides additional evidence for semi-dominant inheritance. METHODS AND RESULTS Molecular analysis of the OPA1 gene in this family by Sanger sequencing revealed compound heterozygosity for two mutations in trans configuration, a p.I382 M missense mutation and a p.V903GfsX3 frameshift deletion in both affected siblings. Electron microscopy of a skeletal muscle biopsy of the older sibling revealed dense osmiophilic bodies within the mitochondria. Mitochondrial DNA (mtDNA) content was within normal limits, and electron transport chain analysis showed no deficiencies of the mitochondrial respiratory chain enzymes. Multiple mtDNA deletions were not found. CONCLUSION Compound heterozygosity of pathogenic OPA1 mutations may cause severe neuromuscular phenotypes in addition to early-onset optic atrophy. While a role for OPA1 in mtDNA maintenance has been discussed, compound biallelic pathogenic OPA1 mutations in our patients did not result in altered mtDNA copy number, mtDNA deletions, or deficiencies of the electron transport chain, despite the severe clinical phenotype.
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Affiliation(s)
- Christian P Schaaf
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
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