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Díaz-Zaragoza M, Hernández-Ávila R, Landa A, Ostoa-Saloma P. Variation of the 2D Pattern of Brain Proteins in Mice Infected with Taenia crassiceps ORF Strain. Int J Mol Sci 2024; 25:1460. [PMID: 38338740 PMCID: PMC10855729 DOI: 10.3390/ijms25031460] [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: 12/16/2023] [Revised: 01/12/2024] [Accepted: 01/22/2024] [Indexed: 02/12/2024] Open
Abstract
Some parasites are known to influence brain proteins or induce changes in the functioning of the nervous system. In this study, our objective is to demonstrate how the two-dimensional gel technique is valuable for detecting differences in protein expression and providing detailed information on changes in the brain proteome during a parasitic infection. Subsequently, we seek to understand how the parasitic infection affects the protein composition in the brain and how this may be related to changes in brain function. By analyzing de novo-expressed proteins at 2, 4, and 8 weeks post-infection compared to the brains of the control mice, we observed that proteins expressed at 2 weeks are primarily associated with neuroprotection or the initial response of the mouse brain to the infection. At 8 weeks, parasitic infection can induce oxidative stress in the brain, potentially activating signaling pathways related to the response to cellular damage. Proteins expressed at 8 weeks exhibit a pattern indicating that, as the host fails to balance the Neuro-Immuno-Endocrine network of the organism, the brain begins to undergo an apoptotic process and consequently experiences brain damage.
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Affiliation(s)
- Mariana Díaz-Zaragoza
- Departamento de Ciencias de la Salud, Centro Universitario de los Valles, Universidad de Guadalajara, Carretera Guadalajara-Ameca Km. 45.5, Guadalajara 46600, Mexico;
| | - Ricardo Hernández-Ávila
- Departamento de Inmunología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, A.P. 70228, Mexico City 04510, Mexico;
| | - Abraham Landa
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad Universitaria, A.P. 70228, Mexico City 04510, Mexico;
| | - Pedro Ostoa-Saloma
- Departamento de Inmunología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, A.P. 70228, Mexico City 04510, Mexico;
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Averina OA, Kuznetsova SA, Permyakov OA, Sergiev PV. Animal Models of Mitochondrial Diseases Associated with Nuclear Gene Mutations. Acta Naturae 2023; 15:4-22. [PMID: 38234606 PMCID: PMC10790356 DOI: 10.32607/actanaturae.25442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Accepted: 10/05/2023] [Indexed: 01/19/2024] Open
Abstract
Mitochondrial diseases (MDs) associated with nuclear gene mutations are part of a large group of inherited diseases caused by the suppression of energy metabolism. These diseases are of particular interest, because nuclear genes encode not only most of the structural proteins of the oxidative phosphorylation system (OXPHOS), but also all the proteins involved in the OXPHOS protein import from the cytoplasm and their assembly in mitochondria. Defects in any of these proteins can lead to functional impairment of the respiratory chain, including dysfunction of complex I that plays a central role in cellular respiration and oxidative phosphorylation, which is the most common cause of mitopathologies. Mitochondrial diseases are characterized by an early age of onset and a progressive course and affect primarily energy-consuming tissues and organs. The treatment of MDs should be initiated as soon as possible, but the diagnosis of mitopathologies is extremely difficult because of their heterogeneity and overlapping clinical features. The molecular pathogenesis of mitochondrial diseases is investigated using animal models: i.e. animals carrying mutations causing MD symptoms in humans. The use of mutant animal models opens new opportunities in the study of genes encoding mitochondrial proteins, as well as the molecular mechanisms of mitopathology development, which is necessary for improving diagnosis and developing approaches to drug therapy. In this review, we present the most recent information on mitochondrial diseases associated with nuclear gene mutations and animal models developed to investigate them.
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Affiliation(s)
- O. A. Averina
- Institute of Functional Genomics, Lomonosov Moscow State University, Moscow, 119991 Russian Federation
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991 Russian Federation
- Department of Chemistry, Lomonosov Moscow State University, Moscow, 119991 Russian Federation
| | - S. A. Kuznetsova
- Institute of Functional Genomics, Lomonosov Moscow State University, Moscow, 119991 Russian Federation
| | - O. A. Permyakov
- Institute of Functional Genomics, Lomonosov Moscow State University, Moscow, 119991 Russian Federation
- Department of Chemistry, Lomonosov Moscow State University, Moscow, 119991 Russian Federation
| | - P. V. Sergiev
- Institute of Functional Genomics, Lomonosov Moscow State University, Moscow, 119991 Russian Federation
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991 Russian Federation
- Department of Chemistry, Lomonosov Moscow State University, Moscow, 119991 Russian Federation
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Olkhova EA, Smith LA, Bradshaw C, Gorman GS, Erskine D, Ng YS. Neurological Phenotypes in Mouse Models of Mitochondrial Disease and Relevance to Human Neuropathology. Int J Mol Sci 2023; 24:ijms24119698. [PMID: 37298649 DOI: 10.3390/ijms24119698] [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: 05/13/2023] [Revised: 05/24/2023] [Accepted: 05/29/2023] [Indexed: 06/12/2023] Open
Abstract
Mitochondrial diseases represent the most common inherited neurometabolic disorders, for which no effective therapy currently exists for most patients. The unmet clinical need requires a more comprehensive understanding of the disease mechanisms and the development of reliable and robust in vivo models that accurately recapitulate human disease. This review aims to summarise and discuss various mouse models harbouring transgenic impairments in genes that regulate mitochondrial function, specifically their neurological phenotype and neuropathological features. Ataxia secondary to cerebellar impairment is one of the most prevalent neurological features of mouse models of mitochondrial dysfunction, consistent with the observation that progressive cerebellar ataxia is a common neurological manifestation in patients with mitochondrial disease. The loss of Purkinje neurons is a shared neuropathological finding in human post-mortem tissues and numerous mouse models. However, none of the existing mouse models recapitulate other devastating neurological phenotypes, such as refractory focal seizures and stroke-like episodes seen in patients. Additionally, we discuss the roles of reactive astrogliosis and microglial reactivity, which may be driving the neuropathology in some of the mouse models of mitochondrial dysfunction, as well as mechanisms through which cellular death may occur, beyond apoptosis, in neurons undergoing mitochondrial bioenergy crisis.
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Affiliation(s)
- Elizaveta A Olkhova
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Laura A Smith
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Carla Bradshaw
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Gráinne S Gorman
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE2 4HH, UK
- NIHR Newcastle Biomedical Research Centre, Biomedical Research Building, Campus for Ageing and Vitality, Newcastle upon Tyne NE4 5PL, UK
| | - Daniel Erskine
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- NIHR Newcastle Biomedical Research Centre, Biomedical Research Building, Campus for Ageing and Vitality, Newcastle upon Tyne NE4 5PL, UK
| | - Yi Shiau Ng
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- NHS Highly Specialised Service for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne NE2 4HH, UK
- NIHR Newcastle Biomedical Research Centre, Biomedical Research Building, Campus for Ageing and Vitality, Newcastle upon Tyne NE4 5PL, UK
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Harada N, Nagasaki H, Yamamoto H, Matsubara K, Suzuki T, Gomori A, Yokogawa T, Matsuo K, Miyadera K. Depletion of plasma thymidine results in growth retardation and mitochondrial myopathy in mice overexpressing human thymidine phosphorylase. J Biol Chem 2023; 299:103002. [PMID: 36773803 PMCID: PMC10020661 DOI: 10.1016/j.jbc.2023.103002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 02/06/2023] [Accepted: 02/07/2023] [Indexed: 02/11/2023] Open
Abstract
Plasma thymidine levels in rodents are higher than in other mammals including humans, possibly due to a different pattern and lower level of thymidine phosphorylase expression. Here, we generated a novel knock-in (KI) mouse line with high systemic expression of human thymidine phosphorylase to investigate this difference in nucleotide metabolism in rodents. The KI mice showed growth retardation around weaning and died by 4 weeks of age with a decrease in plasma thymidine level compared with the litter-control WT mice. These phenotypes were completely or partially rescued by administration of the thymidine phosphorylase inhibitor 5-chloro-6-(2-iminopyrrolidin-1-yl) methyl-2,4(1H,3H)-pyrimidinedione hydrochloride or thymidine, respectively. Interestingly, when thymidine phosphorylase inhibitor administration was discontinued in adult animals, KI mice showed deteriorated grip strength and locomotor activity, decreased bodyweight, and subsequent hind-limb paralysis. Upon histological analyses, we observed axonal degeneration in the spinal cord, muscular atrophy with morphologically abnormal mitochondria in quadriceps, retinal degeneration, and abnormality in the exocrine pancreas. Moreover, we detected mitochondrial DNA depletion in multiple tissues of KI mice. These results indicate that the KI mouse represents a new animal model for mitochondrial diseases and should be applicable for the study of differences in nucleotide metabolism between humans and mice.
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Affiliation(s)
- Naomoto Harada
- Discovery and Preclinical Research Division, Taiho Pharmaceutical Co Ltd, Tsukuba, Ibaraki, Japan.
| | - Haruka Nagasaki
- Discovery and Preclinical Research Division, Taiho Pharmaceutical Co Ltd, Tsukuba, Ibaraki, Japan
| | - Hiromi Yamamoto
- Discovery and Preclinical Research Division, Taiho Pharmaceutical Co Ltd, Tsukuba, Ibaraki, Japan
| | - Kenji Matsubara
- Discovery and Preclinical Research Division, Taiho Pharmaceutical Co Ltd, Tsukuba, Ibaraki, Japan
| | - Takamasa Suzuki
- Discovery and Preclinical Research Division, Taiho Pharmaceutical Co Ltd, Tsukuba, Ibaraki, Japan
| | - Akira Gomori
- Discovery and Preclinical Research Division, Taiho Pharmaceutical Co Ltd, Tsukuba, Ibaraki, Japan
| | - Tatsushi Yokogawa
- Discovery and Preclinical Research Division, Taiho Pharmaceutical Co Ltd, Tsukuba, Ibaraki, Japan
| | - Kenichi Matsuo
- Discovery and Preclinical Research Division, Taiho Pharmaceutical Co Ltd, Tsukuba, Ibaraki, Japan
| | - Kazutaka Miyadera
- Discovery and Preclinical Research Division, Taiho Pharmaceutical Co Ltd, Tsukuba, Ibaraki, Japan
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Thymidine Kinase 2 and Mitochondrial Protein COX I in the Cerebellum of Patients with Spinocerebellar Ataxia Type 31 Caused by Penta-nucleotide Repeats (TTCCA) n. CEREBELLUM (LONDON, ENGLAND) 2023; 22:70-84. [PMID: 35084690 PMCID: PMC9883315 DOI: 10.1007/s12311-021-01364-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 12/23/2021] [Indexed: 02/01/2023]
Abstract
Spinocerebellar ataxia type 31 (SCA31), an autosomal-dominant neurodegenerative disorder characterized by progressive cerebellar ataxia with Purkinje cell degeneration, is caused by a heterozygous 2.5-3.8 kilobase penta-nucleotide repeat of (TTCCA)n in intron 11 of the thymidine kinase 2 (TK2) gene. TK2 is an essential mitochondrial pyrimidine-deoxyribonucleoside kinase. Bi-allelic loss-of-function mutations of TK2 lead to mitochondrial DNA depletion syndrome (MDS) in humans through severe (~ 70%) reduction of mitochondrial electron-transport-chain activity, and tk2 knockout mice show Purkinje cell degeneration and ataxia through severe mitochondrial cytochrome-c oxidase subunit I (COX I) protein reduction. To clarify whether TK2 function is altered in SCA31, we investigated TK2 and COX I expression in human postmortem SCA31 cerebellum. We confirmed that canonical TK2 mRNA is transcribed from exons far upstream of the repeat site, and demonstrated that an extended version of TK2 mRNA ("TK2-EXT"), transcribed from exons spanning the repeat site, is expressed in human cerebellum. While canonical TK2 was conserved among vertebrates, TK2-EXT was specific to primates. Reverse transcription-PCR demonstrated that both TK2 mRNAs were preserved in SCA31 cerebella compared with control cerebella. The TK2 proteins, assessed with three different antibodies including our original polyclonal antibody against TK2-EXT, were detected as ~ 26 kilodalton proteins on western blot; their levels were similar in SCA31 and control cerebella. COX I protein level was preserved in SCA31 compared to nuclear DNA-encoded protein. We conclude that the expression and function of TK2 are preserved in SCA31, suggesting a mechanism distinct from that of MDS.
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Chen K, Chen C, Li H, Yang J, Xiang M, Wang H, Xie Z. Widespread translational control regulates retinal development in mouse. Nucleic Acids Res 2021; 49:9648-9664. [PMID: 34469513 PMCID: PMC8464051 DOI: 10.1093/nar/gkab749] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 08/26/2021] [Indexed: 11/30/2022] Open
Abstract
Retinal development is tightly regulated to ensure the generation of appropriate cell types and the assembly of functional neuronal circuitry. Despite remarkable advances have been made in understanding regulation of gene expression during retinal development, how translational regulation guides retinogenesis is less understood. Here, we conduct a comprehensive translatome and transcriptome survey to the mouse retinogenesis from the embryonic to the adult stages. We discover thousands of genes that have dynamic changes at the translational level and pervasive translational regulation in a developmental stage-specific manner with specific biological functions. We further identify genes whose translational efficiencies are frequently controlled by changing usage in upstream open reading frame during retinal development. These genes are enriched for biological functions highly important to neurons, such as neuron projection organization and microtubule-based protein transport. Surprisingly, we discover hundreds of previously uncharacterized micropeptides, translated from putative long non-coding RNAs and circular RNAs. We validate their protein products in vitro and in vivo and demonstrate their potentials in regulating retinal development. Together, our study presents a rich and complex landscape of translational regulation and provides novel insights into their roles during retinogenesis.
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Affiliation(s)
- Kaining Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
| | - Congying Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
| | - Huihui Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
| | - Jiaqi Yang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
| | - Mengqing Xiang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
| | - Hongwei Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
| | - Zhi Xie
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
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Proteomic Characterization of Synaptosomes from Human Substantia Nigra Indicates Altered Mitochondrial Translation in Parkinson's Disease. Cells 2020; 9:cells9122580. [PMID: 33276480 PMCID: PMC7761546 DOI: 10.3390/cells9122580] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 11/17/2020] [Accepted: 11/24/2020] [Indexed: 12/25/2022] Open
Abstract
The pathological hallmark of Parkinson's disease (PD) is the loss of neuromelanin-containing dopaminergic neurons within the substantia nigra pars compacta (SNpc). Additionally, numerous studies indicate an altered synaptic function during disease progression. To gain new insights into the molecular processes underlying the alteration of synaptic function in PD, a proteomic study was performed. Therefore, synaptosomes were isolated by density gradient centrifugation from SNpc tissue of individuals at advanced PD stages (N = 5) as well as control subjects free of pathology (N = 5) followed by mass spectrometry-based analysis. In total, 362 proteins were identified and assigned to the synaptosomal core proteome. This core proteome comprised all proteins expressed within the synapses without regard to data analysis software, gender, age, or disease. The differential analysis between control subjects and PD cases revealed that CD9 antigen was overrepresented and fourteen proteins, among them Thymidine kinase 2 (TK2), mitochondrial, 39S ribosomal protein L37, neurolysin, and Methionine-tRNA ligase (MARS2) were underrepresented in PD suggesting an alteration in mitochondrial translation within synaptosomes.
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Castellani CA, Longchamps RJ, Sun J, Guallar E, Arking DE. Thinking outside the nucleus: Mitochondrial DNA copy number in health and disease. Mitochondrion 2020; 53:214-223. [PMID: 32544465 DOI: 10.1016/j.mito.2020.06.004] [Citation(s) in RCA: 171] [Impact Index Per Article: 42.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Revised: 05/19/2020] [Accepted: 06/08/2020] [Indexed: 02/07/2023]
Abstract
Mitochondrial DNA copy number (mtDNA-CN) is a biomarker of mitochondrial function and levels of mtDNA-CN have been reproducibly associated with overall mortality and a number of age-related diseases, including cardiovascular disease, chronic kidney disease, and cancer. Recent advancements in techniques for estimating mtDNA-CN, in particular the use of DNA microarrays and next-generation sequencing data, have led to the comprehensive assessment of mtDNA-CN across these and other diseases and traits. The importance of mtDNA-CN measures to disease and these advancing technologies suggest the potential for mtDNA-CN to be a useful biomarker in the clinic. While the exact mechanism(s) underlying the association of mtDNA-CN with disease remain to be elucidated, we review the existing literature which supports roles for inflammatory dynamics, immune function and alterations to cell signaling as consequences of variation in mtDNA-CN. We propose that future studies should focus on characterizing longitudinal, cell-type and cross-tissue profiles of mtDNA-CN as well as improving methods for measuring mtDNA-CN which will expand the potential for its use as a clinical biomarker.
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Affiliation(s)
- Christina A Castellani
- McKusick-Nathans Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Ryan J Longchamps
- McKusick-Nathans Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Jing Sun
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Eliseo Guallar
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States; The Welch Center for Prevention, Epidemiology and Clinical Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Dan E Arking
- McKusick-Nathans Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States.
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Tsialtas I, Gorgogietas VA, Michalopoulou M, Komninou A, Liakou E, Georgantopoulos A, Kalousi FD, Karra AG, Protopapa E, Psarra AMG. Neurotoxic effects of aluminum are associated with its interference with estrogen receptors signaling. Neurotoxicology 2020; 77:114-126. [PMID: 31945389 DOI: 10.1016/j.neuro.2020.01.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 01/10/2020] [Accepted: 01/12/2020] [Indexed: 12/20/2022]
Abstract
Aluminum compounds have been observed in various brain regions, and their accumulation has been associated with many neurodegenerative disorders. Neurotoxic effects of aluminum are attributed to reactive oxygen species generation, induction of apoptosis and inflammatory reactions activation. Metalloestrogen activity of aluminum has also been linked to breast cancer progression and metastasis. In this study, taking into account the anti-apoptotic and anti-oxidant activities of estrogens in neuronal cells, which are mediated by estrogen receptors, the possible estrogenic activity of aluminum in SH-SY5Y neuroblastoma cells was studied. Our results showed that aluminum in the form of aluminum chlorohydrate (ACH) exhibited no effect on estrogen receptors transcriptional activation, and differential effect on estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ) protein levels. ACH caused reduction in ERβ protein levels, and increase in its mitochondrial localization. ACH-induced reduction in ERβ protein level may be linked, at least in part, to the ACH-induced increase in ERα protein level. This statement is based on our observations showing aluminum-induced reduction in the E2-induced increase in ERα S118 phosphorylation, in MCF-7 and SH-SH5Y cells. Phosphorylation at S118 residue is known to be associated with inhibition of the ubiquitin-induced proteolytic degradation of ERα, leading to its accumulation. Since it is known that ERα negatively regulate ERβ expression, increase in ERα, may contribute to reduction in ERβ levels and subsequent weakening of its anti-apoptotic and anti-oxidant activity, justified by the observed reduction in procaspase 9, mitochondrial cytochrome c, Bcl-2, Bcl-xL and mitochondrial thioredoxin protein level, as well as by the increase in proapoptotic BAX level, in ACH treated SH-SY5Y cells. In addition, increase in mitochondrial ERβ localization may also trigger mitochondrial metabolism, suppress biosynthetic process of gluconeogenesis, as indicated by the observed reduction in the phosphoenolpyruvate carboxykinase protein level, and eventually lead to increase in reactive oxygen species (ROS) generation, known to be implicated in aluminum induced neurodegeneration. This statement was verified by the observed ACH-induced increase in ERβ mitochondrial localization, induction of the mitochondrial membrane depolarization and increase in ROS production, in neuronal-like differentiated SH-SY5Y cells.
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Affiliation(s)
- Ioannis Tsialtas
- Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece
| | - Vyron A Gorgogietas
- Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece
| | - Maria Michalopoulou
- Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece
| | - Aggeliki Komninou
- Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece
| | - Eleni Liakou
- Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece
| | | | - Foteini D Kalousi
- Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece
| | - Aikaterini G Karra
- Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece
| | - Evagelia Protopapa
- Department of Aesthetics and Cosmetology, Faculty of Health & Caring Professions, University of West Attica, Egaleo, Greece
| | - Anna-Maria G Psarra
- Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece.
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Blázquez-Bermejo C, Molina-Granada D, Vila-Julià F, Jiménez-Heis D, Zhou X, Torres-Torronteras J, Karlsson A, Martí R, Cámara Y. Age-related metabolic changes limit efficacy of deoxynucleoside-based therapy in thymidine kinase 2-deficient mice. EBioMedicine 2019; 46:342-355. [PMID: 31351931 PMCID: PMC6711114 DOI: 10.1016/j.ebiom.2019.07.042] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 07/05/2019] [Accepted: 07/15/2019] [Indexed: 01/01/2023] Open
Abstract
Background Thymidine kinase 2 (TK2) catalyses the phosphorylation of deoxythymidine (dThd) and deoxycytidine (dCtd) within mitochondria. TK2 deficiency leads to mtDNA depletion or accumulation of multiple deletions. In patients, TK2 mutations typically manifest as a rapidly progressive myopathy with infantile onset, leading to respiratory insufficiency and encephalopathy in the most severe clinical presentations. TK2-deficient mice develop the most severe form of the disease and die at average postnatal day 16. dThd+dCtd administration delayed disease progression and expanded lifespan of a knockin murine model of the disease. Methods We daily administered TK2 knockout mice (Tk2KO) from postnatal day 4 with equimolar doses of dThd+dCtd, dTMP+dCMP, dThd alone or dCtd alone. We monitored body weight and survival and studied different variables at 12 or 29 days of age. We determined metabolite levels in plasma and target tissues, mtDNA copy number in tissues, and the expression and activities of enzymes with a relevant role in mitochondrial dNTP anabolism or catabolism. Findings dThd+dCtd treatment extended average lifespan of Tk2KO mice from 16 to 34 days, attenuated growth retardation, and rescued mtDNA depletion in skeletal muscle and other target tissues of 12-day-old mice, except in brain. However, the treatment was ineffective in 29-day-old mice that still died prematurely. Bioavailability of dThd and dCtd markedly decreased during mouse development. Activity of enzymes catabolizing dThd and dCtd increased with age in small intestine. Conversely, the activity of the anabolic enzymes decreased in target tissues during mouse development. We also found that administration of dThd alone had the same impact on survival to that of dThd+dCtd, whereas dCtd alone had no influence on lifespan. Interpretation dThd+dCtd treatment recruits alternative cytosolic salvage pathways for dNTP synthesis, suggesting that this therapy would be of benefit for any Tk2 mutation. dThd accounts for the therapeutic effect of the combined treatment in mice. During the first weeks after birth, mice experience marked tissue-specific metabolic regulations and ontogenetic changes in dNTP metabolism-related enzymes that limit therapeutic efficacy to early developmental stages. Fund This study was funded by grants from the Spanish Ministry of Industry, Economy and Competitiveness, the Spanish Instituto de Salud Carlos III, the Fundación Inocente, Inocente, AFM Téléthon and the Generalitat de Catalunya. The disclosed funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
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Affiliation(s)
- Cora Blázquez-Bermejo
- Research Group on Neuromuscular and Mitochondrial Disorders, Vall d'Hebron Institut de Recerca, Universitat Autònoma de Barcelona, Barcelona, Spain; Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | - David Molina-Granada
- Research Group on Neuromuscular and Mitochondrial Disorders, Vall d'Hebron Institut de Recerca, Universitat Autònoma de Barcelona, Barcelona, Spain; Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | - Ferran Vila-Julià
- Research Group on Neuromuscular and Mitochondrial Disorders, Vall d'Hebron Institut de Recerca, Universitat Autònoma de Barcelona, Barcelona, Spain; Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | - Daniel Jiménez-Heis
- Research Group on Neuromuscular and Mitochondrial Disorders, Vall d'Hebron Institut de Recerca, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Xiaoshan Zhou
- Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska Institute, Karolinska University Hospital, 141 86 Stockholm, Sweden
| | - Javier Torres-Torronteras
- Research Group on Neuromuscular and Mitochondrial Disorders, Vall d'Hebron Institut de Recerca, Universitat Autònoma de Barcelona, Barcelona, Spain; Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | - Anna Karlsson
- Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska Institute, Karolinska University Hospital, 141 86 Stockholm, Sweden
| | - Ramon Martí
- Research Group on Neuromuscular and Mitochondrial Disorders, Vall d'Hebron Institut de Recerca, Universitat Autònoma de Barcelona, Barcelona, Spain; Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | - Yolanda Cámara
- Research Group on Neuromuscular and Mitochondrial Disorders, Vall d'Hebron Institut de Recerca, Universitat Autònoma de Barcelona, Barcelona, Spain; Biomedical Network Research Centre on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Madrid, Spain.
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Garone C, Taylor RW, Nascimento A, Poulton J, Fratter C, Domínguez-González C, Evans JC, Loos M, Isohanni P, Suomalainen A, Ram D, Hughes MI, McFarland R, Barca E, Lopez Gomez C, Jayawant S, Thomas ND, Manzur AY, Kleinsteuber K, Martin MA, Kerr T, Gorman GS, Sommerville EW, Chinnery PF, Hofer M, Karch C, Ralph J, Cámara Y, Madruga-Garrido M, Domínguez-Carral J, Ortez C, Emperador S, Montoya J, Chakrapani A, Kriger JF, Schoenaker R, Levin B, Thompson JLP, Long Y, Rahman S, Donati MA, DiMauro S, Hirano M. Retrospective natural history of thymidine kinase 2 deficiency. J Med Genet 2018; 55:515-521. [PMID: 29602790 PMCID: PMC6073909 DOI: 10.1136/jmedgenet-2017-105012] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 03/02/2018] [Accepted: 03/11/2018] [Indexed: 12/21/2022]
Abstract
Background Thymine kinase 2 (TK2) is a mitochondrial matrix protein encoded in nuclear DNA and phosphorylates the pyrimidine nucleosides: thymidine and deoxycytidine. Autosomal recessive TK2 mutations cause a spectrum of disease from infantile onset to adult onset manifesting primarily as myopathy. Objective To perform a retrospective natural history study of a large cohort of patients with TK2 deficiency. Methods The study was conducted by 42 investigators across 31 academic medical centres. Results We identified 92 patients with genetically confirmed diagnoses of TK2 deficiency: 67 from literature review and 25 unreported cases. Based on clinical and molecular genetics findings, we recognised three phenotypes with divergent survival: (1) infantile-onset myopathy (42.4%) with severe mitochondrial DNA (mtDNA) depletion, frequent neurological involvement and rapid progression to early mortality (median post-onset survival (POS) 1.00, CI 0.58 to 2.33 years); (2) childhood-onset myopathy (40.2%) with mtDNA depletion, moderate-to-severe progression of generalised weakness and median POS at least 13 years; and (3) late-onset myopathy (17.4%) with mild limb weakness at onset and slow progression to respiratory insufficiency with median POS of 23 years. Ophthalmoparesis and facial weakness are frequent in adults. Muscle biopsies show multiple mtDNA deletions often with mtDNA depletion. Conclusions In TK2 deficiency, age at onset, rate of weakness progression and POS are important variables that define three clinical subtypes. Nervous system involvement often complicates the clinical course of the infantile-onset form while extraocular muscle and facial involvement are characteristic of the late-onset form. Our observations provide essential information for planning future clinical trials in this disorder.
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Affiliation(s)
- Caterina Garone
- Department of Neurology, Columbia University Medical Center, New York City, New York, USA.,MRC Mitochondrial Biology Unit, Cambridge Biomedical Campus, Cambridge, UK
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Andrés Nascimento
- Neuromuscular Unit, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - Joanna Poulton
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Oxford, UK
| | - Carl Fratter
- Oxford Medical Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Cristina Domínguez-González
- Neuromuscular Unit, Hospital Universitario 12 de Octubre, Madrid, Spain.,Centre for Biomedical Network Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Madrid, Spain.,Instituto de Investigación, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - Julie C Evans
- Oxford Medical Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Mariana Loos
- Neurology Department, Hospital de Pediatría 'Prof. Dr JP Garrahan', Buenos Aires, Argentina
| | - Pirjo Isohanni
- Research Programs Unit, Molecular Neurology, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland.,Department of Child Neurology, Children's Hospital, University of Helsinki, Helsinki University Hospital, Helsinki, Finland
| | - Anu Suomalainen
- Research Programs Unit, Molecular Neurology, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland.,Neuroscience Center, University of Helsinki, Helsinki, Finland.,Department of Neurology, Helsinki University Hospital, Helsinki, Finland
| | - Dipak Ram
- Department of Paediatric Neurology, Royal Manchester Children's Hospital, Manchester, UK
| | - M Imelda Hughes
- Department of Paediatric Neurology, Royal Manchester Children's Hospital, Manchester, UK
| | - Robert McFarland
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Emanuele Barca
- Department of Neurology, Columbia University Medical Center, New York City, New York, USA.,UOC Neurology and Neuromuscular Diseases, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Carlos Lopez Gomez
- Department of Neurology, Columbia University Medical Center, New York City, New York, USA
| | - Sandeep Jayawant
- Paediatric Neurology, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Neil D Thomas
- Paediatric Neurology, University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | - Adnan Y Manzur
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Karin Kleinsteuber
- Pediatric Neurology, Faculty of Medicine, Universidad de Chile, Clínica Las Condes, Santiago, Chile
| | - Miguel A Martin
- Centre for Biomedical Network Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Madrid, Spain.,Instituto de Investigación, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - Timothy Kerr
- Paediatric Neurology, St George's University Hospitals NHS Foundation Trust, London, UK
| | - Grainne S Gorman
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Ewen W Sommerville
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Patrick F Chinnery
- MRC Mitochondrial Biology Unit, Cambridge Biomedical Campus, Cambridge, UK.,Wellcome Trust Centre for Mitochondrial Research, Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Monika Hofer
- Department of Neuropathology, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Christoph Karch
- Department of Neurology, University of California San Francisco, San Francisco, California, USA
| | - Jeffrey Ralph
- Department of Neurology, University of California San Francisco, San Francisco, California, USA
| | - Yolanda Cámara
- Research Group on Neuromuscular and Mitochondrial Disorders, Vall d'Hebron Institut de Recerca, Barcelona, Spain.,Centre for Biomedical Network Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Barcelona, Spain
| | - Marcos Madruga-Garrido
- Sección de Neuropediatría, Hospital Universitario Virgen del Rocío, Instituto de Biomedicina de Sevilla, Seville, Spain
| | - Jana Domínguez-Carral
- Neuromuscular Unit, Department of Neurology, Hospital Sant Joan de Déu, CIBERER, ISCIII, Universitat de Barcelona, Barcelona, Spain
| | - Carlos Ortez
- Neuromuscular Unit, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - Sonia Emperador
- Department of Biochemistry and Molecular Biology, University of Zaragoza-CIBERER-Instituto de investigaciones Sanitarias de Aragón, Zaragoza, Spain
| | - Julio Montoya
- Department of Biochemistry and Molecular Biology, University of Zaragoza-CIBERER-Instituto de investigaciones Sanitarias de Aragón, Zaragoza, Spain
| | - Anupam Chakrapani
- Metabolic Unit, Great Ormond Street Hospital NHS Foundation Trust, London, UK
| | - Joshua F Kriger
- Department of Biostatistics, Mailman School of Public Health, Columbia University Medical Center, New York City, New York, USA
| | - Robert Schoenaker
- Department of Neurology, Columbia University Medical Center, New York City, New York, USA
| | - Bruce Levin
- Department of Biostatistics, Mailman School of Public Health, Columbia University Medical Center, New York City, New York, USA
| | - John L P Thompson
- Department of Biostatistics, Mailman School of Public Health, Columbia University Medical Center, New York City, New York, USA
| | - Yuelin Long
- Department of Biostatistics, Mailman School of Public Health, Columbia University Medical Center, New York City, New York, USA
| | - Shamima Rahman
- Metabolic Unit, Great Ormond Street Hospital NHS Foundation Trust, London, UK.,Mitochondrial Research Group, Genetics and Genomic Medicine, UCL Great Ormond Street Institute of Child Health, London, UK
| | | | - Salvatore DiMauro
- Department of Neurology, Columbia University Medical Center, New York City, New York, USA
| | - Michio Hirano
- Department of Neurology, Columbia University Medical Center, New York City, New York, USA
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12
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Wang T, Zhang M, Jiang Z, Seli E. Mitochondrial dysfunction and ovarian aging. Am J Reprod Immunol 2017; 77. [PMID: 28194828 DOI: 10.1111/aji.12651] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 01/17/2017] [Indexed: 01/02/2023] Open
Abstract
Mitochondria are double-membrane-bound organelles that are responsible for the generation of most of the cell's energy. Mitochondrial dysfunction has been implicated in cellular senescence in general and ovarian aging in particular. Recent studies exploited this association by studying mitochondrial DNA (mtDNA) copy number as a potential biomarker of embryo viability and the use of mitochondrial nutrients and autologous mitochondrial transfer as a potential treatment for poor ovarian function and response.
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Affiliation(s)
- Tianren Wang
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA
| | - Man Zhang
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA
| | - Zongliang Jiang
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA
| | - Emre Seli
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA
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13
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Ripolone M, Ronchi D, Violano R, Vallejo D, Fagiolari G, Barca E, Lucchini V, Colombo I, Villa L, Berardinelli A, Balottin U, Morandi L, Mora M, Bordoni A, Fortunato F, Corti S, Parisi D, Toscano A, Sciacco M, DiMauro S, Comi GP, Moggio M. Impaired Muscle Mitochondrial Biogenesis and Myogenesis in Spinal Muscular Atrophy. JAMA Neurol 2015; 72:666-75. [PMID: 25844556 PMCID: PMC4944827 DOI: 10.1001/jamaneurol.2015.0178] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
IMPORTANCE The important depletion of mitochondrial DNA (mtDNA) and the general depression of mitochondrial respiratory chain complex levels (including complex II) have been confirmed, implying an increasing paucity of mitochondria in the muscle from patients with types I, II, and III spinal muscular atrophy (SMA-I, -II, and -III, respectively). OBJECTIVE To investigate mitochondrial dysfunction in a large series of muscle biopsy samples from patients with SMA. DESIGN, SETTING, AND PARTICIPANTS We studied quadriceps muscle samples from 24 patients with genetically documented SMA and paraspinal muscle samples from 3 patients with SMA-II undergoing surgery for scoliosis correction. Postmortem muscle samples were obtained from 1 additional patient. Age-matched controls consisted of muscle biopsy specimens from healthy children aged 1 to 3 years who had undergone analysis for suspected myopathy. Analyses were performed at the Neuromuscular Unit, Istituto di Ricovero e Cura a Carattere Scientifico Foundation Ca' Granda Ospedale Maggiore Policlinico-Milano, from April 2011 through January 2015. EXPOSURES We used histochemical, biochemical, and molecular techniques to examine the muscle samples. MAIN OUTCOMES AND MEASURES Respiratory chain activity and mitochondrial content. RESULTS Results of histochemical analysis revealed that cytochrome-c oxidase (COX) deficiency was more evident in muscle samples from patients with SMA-I and SMA-II. Residual activities for complexes I, II, and IV in muscles from patients with SMA-I were 41%, 27%, and 30%, respectively, compared with control samples (P < .005). Muscle mtDNA content and cytrate synthase activity were also reduced in all 3 SMA types (P < .05). We linked these alterations to downregulation of peroxisome proliferator-activated receptor coactivator 1α, the transcriptional activators nuclear respiratory factor 1 and nuclear respiratory factor 2, mitochondrial transcription factor A, and their downstream targets, implying depression of the entire mitochondrial biogenesis. Results of Western blot analysis confirmed the reduced levels of the respiratory chain subunits that included mitochondrially encoded COX1 (47.5%; P = .004), COX2 (32.4%; P < .001), COX4 (26.6%; P < .001), and succinate dehydrogenase complex subunit A (65.8%; P = .03) as well as the structural outer membrane mitochondrial porin (33.1%; P < .001). Conversely, the levels of expression of 3 myogenic regulatory factors-muscle-specific myogenic factor 5, myoblast determination 1, and myogenin-were higher in muscles from patients with SMA compared with muscles from age-matched controls (P < .05). CONCLUSIONS AND RELEVANCE Our results strongly support the conclusion that an altered regulation of myogenesis and a downregulated mitochondrial biogenesis contribute to pathologic change in the muscle of patients with SMA. Therapeutic strategies should aim at counteracting these changes.
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Affiliation(s)
- Michela Ripolone
- Neuromuscular Unit, Dino Ferrari Centre, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Foundation Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Dario Ronchi
- Neurology Unit, Neuroscience Section, Department of Pathophysiology and Transplantation, Dino Ferrari Centre, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Raffaella Violano
- Neuromuscular Unit, Dino Ferrari Centre, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Foundation Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Dionis Vallejo
- Sien-Servicios Integrales en Neurologia, Universidad de Antioquia, Medellin, Colombia
| | - Gigliola Fagiolari
- Neuromuscular Unit, Dino Ferrari Centre, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Foundation Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Emanuele Barca
- Department of Neurology, Columbia University Medical Center, New York, New York
| | - Valeria Lucchini
- Neuromuscular Unit, Dino Ferrari Centre, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Foundation Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Irene Colombo
- Neuromuscular Unit, Dino Ferrari Centre, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Foundation Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Luisa Villa
- Neuromuscular Unit, Dino Ferrari Centre, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Foundation Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Angela Berardinelli
- Child Neuropsychiatry Unit, C. Mondino National Neurological Institute, Pavia, Italy
| | - Umberto Balottin
- Child Neuropsychiatry Unit, C. Mondino National Neurological Institute, Pavia, Italy
| | - Lucia Morandi
- Neuromuscular Diseases and Neuroimmunology Unit, Department of Clinical Neurosciences, IRCCS Foundation, Carlo Besta Neurological Institute, Milan, Italy
| | - Marina Mora
- Neuromuscular Diseases and Neuroimmunology Unit, Department of Clinical Neurosciences, IRCCS Foundation, Carlo Besta Neurological Institute, Milan, Italy
| | - Andreina Bordoni
- Neurology Unit, Neuroscience Section, Department of Pathophysiology and Transplantation, Dino Ferrari Centre, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Francesco Fortunato
- Neurology Unit, Neuroscience Section, Department of Pathophysiology and Transplantation, Dino Ferrari Centre, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Stefania Corti
- Neurology Unit, Neuroscience Section, Department of Pathophysiology and Transplantation, Dino Ferrari Centre, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Daniela Parisi
- Reference Center for Rare Neuromuscular Disorders, Department of Neurosciences, University of Messina, Azienda Ospedaliera Universitaria Policlinico G. Martino, Messina, Italy
| | - Antonio Toscano
- Reference Center for Rare Neuromuscular Disorders, Department of Neurosciences, University of Messina, Azienda Ospedaliera Universitaria Policlinico G. Martino, Messina, Italy
| | - Monica Sciacco
- Neuromuscular Unit, Dino Ferrari Centre, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Foundation Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Salvatore DiMauro
- Department of Neurology, Columbia University Medical Center, New York, New York
| | - Giacomo P Comi
- Neurology Unit, Neuroscience Section, Department of Pathophysiology and Transplantation, Dino Ferrari Centre, IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Maurizio Moggio
- Neuromuscular Unit, Dino Ferrari Centre, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Foundation Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
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14
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Iommarini L, Peralta S, Torraco A, Diaz F. Mitochondrial Diseases Part II: Mouse models of OXPHOS deficiencies caused by defects in regulatory factors and other components required for mitochondrial function. Mitochondrion 2015; 22:96-118. [PMID: 25640959 DOI: 10.1016/j.mito.2015.01.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 01/22/2015] [Indexed: 01/21/2023]
Abstract
Mitochondrial disorders are defined as defects that affect the oxidative phosphorylation system (OXPHOS). They are characterized by a heterogeneous array of clinical presentations due in part to a wide variety of factors required for proper function of the components of the OXPHOS system. There is no cure for these disorders owing to our poor knowledge of the pathogenic mechanisms of disease. To understand the mechanisms of human disease numerous mouse models have been developed in recent years. Here we summarize the features of several mouse models of mitochondrial diseases directly related to those factors affecting mtDNA maintenance, replication, transcription, translation as well as other proteins that are involved in mitochondrial dynamics and quality control which affect mitochondrial OXPHOS function without being intrinsic components of the system. We discuss how these models have contributed to our understanding of mitochondrial diseases and their pathogenic mechanisms.
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Affiliation(s)
- Luisa Iommarini
- Department of Pharmacy and Biotechnology (FABIT), University of Bologna, Via Irnerio 42, 40128 Bologna, Italy.
| | - Susana Peralta
- Department of Neurology, University of Miami, Miller School of Medicine, Miami, FL 33136, USA.
| | - Alessandra Torraco
- Unit for Neuromuscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesù Children's Hospital, IRCCS, Viale di San Paolo, 15 - 00146, Rome, Italy.
| | - Francisca Diaz
- Department of Neurology, University of Miami, Miller School of Medicine, Miami, FL 33136, USA.
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15
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Inhibition of oxidative metabolism leads to p53 genetic inactivation and transformation in neural stem cells. Proc Natl Acad Sci U S A 2015; 112:1059-64. [PMID: 25583481 DOI: 10.1073/pnas.1413165112] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Alterations of mitochondrial metabolism and genomic instability have been implicated in tumorigenesis in multiple tissues. High-grade glioma (HGG), one of the most lethal human neoplasms, displays genetic modifications of Krebs cycle components as well as electron transport chain (ETC) alterations. Furthermore, the p53 tumor suppressor, which has emerged as a key regulator of mitochondrial respiration at the expense of glycolysis, is genetically inactivated in a large proportion of HGG cases. Therefore, it is becoming evident that genetic modifications can affect cell metabolism in HGG; however, it is currently unclear whether mitochondrial metabolism alterations could vice versa promote genomic instability as a mechanism for neoplastic transformation. Here, we show that, in neural progenitor/stem cells (NPCs), which can act as HGG cell of origin, inhibition of mitochondrial metabolism leads to p53 genetic inactivation. Impairment of respiration via inhibition of complex I or decreased mitochondrial DNA copy number leads to p53 genetic loss and a glycolytic switch. p53 genetic inactivation in ETC-impaired neural stem cells is caused by increased reactive oxygen species and associated oxidative DNA damage. ETC-impaired cells display a marked growth advantage in the presence or absence of oncogenic RAS, and form undifferentiated tumors when transplanted into the mouse brain. Finally, p53 mutations correlated with alterations in ETC subunit composition and activity in primary glioma-initiating neural stem cells. Together, these findings provide previously unidentified insights into the relationship between mitochondria, genomic stability, and tumor suppressive control, with implications for our understanding of brain cancer pathogenesis.
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16
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Kalko SG, Paco S, Jou C, Rodríguez MA, Meznaric M, Rogac M, Jekovec-Vrhovsek M, Sciacco M, Moggio M, Fagiolari G, De Paepe B, De Meirleir L, Ferrer I, Roig-Quilis M, Munell F, Montoya J, López-Gallardo E, Ruiz-Pesini E, Artuch R, Montero R, Torner F, Nascimento A, Ortez C, Colomer J, Jimenez-Mallebrera C. Transcriptomic profiling of TK2 deficient human skeletal muscle suggests a role for the p53 signalling pathway and identifies growth and differentiation factor-15 as a potential novel biomarker for mitochondrial myopathies. BMC Genomics 2014; 15:91. [PMID: 24484525 PMCID: PMC3937154 DOI: 10.1186/1471-2164-15-91] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 01/28/2014] [Indexed: 02/08/2023] Open
Abstract
Background Mutations in the gene encoding thymidine kinase 2 (TK2) result in the myopathic form of mitochondrial DNA depletion syndrome which is a mitochondrial encephalomyopathy presenting in children. In order to unveil some of the mechanisms involved in this pathology and to identify potential biomarkers and therapeutic targets we have investigated the gene expression profile of human skeletal muscle deficient for TK2 using cDNA microarrays. Results We have analysed the whole transcriptome of skeletal muscle from patients with TK2 mutations and compared it to normal muscle and to muscle from patients with other mitochondrial myopathies. We have identified a set of over 700 genes which are differentially expressed in TK2 deficient muscle. Bioinformatics analysis reveals important changes in muscle metabolism, in particular, in glucose and glycogen utilisation, and activation of the starvation response which affects aminoacid and lipid metabolism. We have identified those transcriptional regulators which are likely to be responsible for the observed changes in gene expression. Conclusion Our data point towards the tumor suppressor p53 as the regulator at the centre of a network of genes which are responsible for a coordinated response to TK2 mutations which involves inflammation, activation of muscle cell death by apoptosis and induction of growth and differentiation factor 15 (GDF-15) in muscle and serum. We propose that GDF-15 may represent a potential novel biomarker for mitochondrial dysfunction although further studies are required.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Cecilia Jimenez-Mallebrera
- Neuromuscular Unit, Neurology Department, Fundación Sant Joan de Déu, Hospital Sant Joan de Déu, Barcelona, Spain.
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17
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Mitochondrial DNA integrity changes with age but does not correlate with learning performance in honey bees. Exp Gerontol 2014; 49:12-8. [DOI: 10.1016/j.exger.2013.10.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Revised: 10/22/2013] [Accepted: 10/28/2013] [Indexed: 11/23/2022]
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18
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Abstract
To highlight differences between early-onset and adult mitochondrial depletion syndromes (MDS) concerning etiology and genetic background, pathogenesis, phenotype, clinical presentation and their outcome. MDSs most frequently occur in neonates, infants, or juveniles and more rarely in adolescents or adults. Mutated genes phenotypically presenting with adult-onset MDS include POLG1, TK2, TyMP, RRM2B, or PEO1/twinkle. Adult MDS manifest similarly to early-onset MDS, as myopathy, encephalo-myopathy, hepato-cerebral syndrome, or with chronic progressive external ophthalmoplegia (CPEO), fatigue, or only minimal muscular manifestations. Diagnostic work-up or treatment is not at variance from early-onset cases. Histological examination of muscle may be normal but biochemical investigations may reveal multiple respiratory chain defects. The outcome appears to be more favorable in adult than in early-onset forms. Mitochondrial depletion syndromes is not only a condition of neonates, infants, or juveniles but rarely also occurs in adults, presenting with minimal manifestations or manifestations like in the early-onset forms. Outcome of adult-onset MDS appears more favorable than early-onset MDS.
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19
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Bird MJ, Thorburn DR, Frazier AE. Modelling biochemical features of mitochondrial neuropathology. Biochim Biophys Acta Gen Subj 2013; 1840:1380-92. [PMID: 24161927 DOI: 10.1016/j.bbagen.2013.10.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 08/29/2013] [Accepted: 10/11/2013] [Indexed: 12/20/2022]
Abstract
BACKGROUND The neuropathology of mitochondrial disease is well characterised. However, pathophysiological mechanisms at the level of biochemistry and cell biology are less clear. Progress in this area has been hampered by the limited accessibility of neurologically relevant material for analysis. SCOPE OF REVIEW Here we discuss the recent development of a variety of model systems that have greatly extended our capacity to understand the biochemical features associated with mitochondrial neuropathology. These include animal and cell based models, with mutations in both nuclear and mitochondrial DNA encoded genes, which aim to recapitulate the neuropathology and cellular biochemistry of mitochondrial diseases. MAJOR CONCLUSIONS Analysis of neurological tissue and cells from these models suggests that although there is no unifying mode of pathogenesis, dysfunction of the oxidative phosphorylation (OXPHOS) system is often central. This can be associated with altered reactive oxygen species (ROS) generation, disruption of the mitochondrial membrane potential (ΔΨm) and inadequate ATP synthesis. Thus, other cellular processes such as calcium (Ca(2+)) homeostasis, cellular signaling and mitochondrial morphology could be altered, ultimately compromising viability of neuronal cells. GENERAL SIGNIFICANCE Mechanisms of neuronal dysfunction in mitochondrial disease are only just beginning to be characterised, are system dependent and complex, and not merely driven by energy deficiency. The diversity of pathogenic mechanisms emphasises the need for characterisation in a wide range of models, as different therapeutic strategies are likely to be needed for different diseases. This article is part of a Special Issue entitled Frontiers of Mitochondrial Research.
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Affiliation(s)
- Matthew J Bird
- The Murdoch Childrens Research Institute, The Royal Children's Hospital, Melbourne, Australia; Department of Paediatrics, The University of Melbourne, Melbourne, Australia
| | - David R Thorburn
- The Murdoch Childrens Research Institute, The Royal Children's Hospital, Melbourne, Australia; Department of Paediatrics, The University of Melbourne, Melbourne, Australia; Victorian Clinical Genetics Services, Royal Children's Hospital, Melbourne, Australia
| | - Ann E Frazier
- The Murdoch Childrens Research Institute, The Royal Children's Hospital, Melbourne, Australia; Department of Paediatrics, The University of Melbourne, Melbourne, Australia.
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20
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Zhou X, Kannisto K, Curbo S, von Döbeln U, Hultenby K, Isetun S, Gåfvels M, Karlsson A. Thymidine kinase 2 deficiency-induced mtDNA depletion in mouse liver leads to defect β-oxidation. PLoS One 2013; 8:e58843. [PMID: 23505564 PMCID: PMC3591375 DOI: 10.1371/journal.pone.0058843] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 02/07/2013] [Indexed: 02/06/2023] Open
Abstract
Thymidine kinase 2 (TK2) deficiency in humans causes mitochondrial DNA (mtDNA) depletion syndrome. To study the molecular mechanisms underlying the disease and search for treatment options, we previously generated and described a TK2 deficient mouse strain (TK2−/−) that progressively loses its mtDNA. The TK2−/− mouse model displays symptoms similar to humans harboring TK2 deficient infantile fatal encephalomyopathy. Here, we have studied the TK2−/− mouse model to clarify the pathological role of progressive mtDNA depletion in liver for the severe outcome of TK2 deficiency. We observed that a gradual depletion of mtDNA in the liver of the TK2−/− mice was accompanied by increasingly hypertrophic mitochondria and accumulation of fat vesicles in the liver cells. The levels of cholesterol and nonesterified fatty acids were elevated and there was accumulation of long chain acylcarnitines in plasma of the TK2−/− mice. In mice with hepatic mtDNA levels below 20%, the blood sugar and the ketone levels dropped. These mice also exhibited reduced mitochondrial β-oxidation due to decreased transport of long chain acylcarnitines into the mitochondria. The gradual loss of mtDNA in the liver of the TK2−/− mice causes impaired mitochondrial function that leads to defect β-oxidation and, as a result, insufficient production of ketone bodies and glucose. This study provides insight into the mechanism of encephalomyopathy caused by TK2 deficiency-induced mtDNA depletion that may be used to explore novel therapeutic strategies.
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Affiliation(s)
- Xiaoshan Zhou
- Division of Clinical Microbiology F-68, Karolinska Institutet, Department of Laboratory Medicine, Karolinska University Hospital, Huddinge, Sweden
| | - Kristina Kannisto
- Division of Clinical Chemistry, C1-72, Karolinska Institutet, Department of Laboratory Medicine, Karolinska University Hospital, Huddinge, Sweden
| | - Sophie Curbo
- Division of Clinical Microbiology F-68, Karolinska Institutet, Department of Laboratory Medicine, Karolinska University Hospital, Huddinge, Sweden
- * E-mail:
| | - Ulrika von Döbeln
- Division of Metabolic Diseases, Karolinska Institutet, Department of Laboratory Medicine, Karolinska University Hospital, Huddinge, Sweden
| | - Kjell Hultenby
- Division of Clinical Research Center, Karolinska Institutet, Department of Laboratory Medicine, Karolinska University Hospital, Huddinge, Sweden
| | - Sindra Isetun
- Division of Metabolic Diseases, Karolinska Institutet, Department of Laboratory Medicine, Karolinska University Hospital, Huddinge, Sweden
| | - Mats Gåfvels
- Division of Clinical Chemistry, C1-72, Karolinska Institutet, Department of Laboratory Medicine, Karolinska University Hospital, Huddinge, Sweden
- Division of Clinical Chemistry, Department of Laboratory Medicine, Lund University, Lund, Sweden
| | - Anna Karlsson
- Division of Clinical Microbiology F-68, Karolinska Institutet, Department of Laboratory Medicine, Karolinska University Hospital, Huddinge, Sweden
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Gene expression deregulation in postnatal skeletal muscle of TK2 deficient mice reveals a lower pool of proliferating myogenic progenitor cells. PLoS One 2013; 8:e53698. [PMID: 23341978 PMCID: PMC3544874 DOI: 10.1371/journal.pone.0053698] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Accepted: 12/03/2012] [Indexed: 01/07/2023] Open
Abstract
Loss of thymidine kinase 2 (TK2) causes a heterogeneous myopathic form of mitochondrial DNA (mtDNA) depletion syndrome (MDS) in humans that predominantly affects skeletal muscle tissue. In mice, TK2 deficiency also affects several tissues in addition to skeletal muscle, including brain, heart, adipose tissue, kidneys and causes death about 3 weeks after birth. We analysed skeletal muscle and heart muscle tissues of Tk2 knockout mice at postnatal development phase and observed that TK2 deficient pups grew slower and their skeletal muscles appeared significantly underdeveloped, whereas heart was close to normal in size. Both tissues showed mtDNA depletion and mitochondria with altered ultrastructure, as revealed by transmission electron microscopy. Gene expression microarray analysis showed a strong down-regulation of genes involved in cell cycle and cell proliferation in both tissues, suggesting a lower pool of undifferentiated proliferating cells. Analysis of isolated primary myoblasts from Tk2 knockout mice showed slow proliferation, less ability to differentiate and signs of premature senescence, even in absence of mtDNA depletion. Our data demonstrate that TK2 deficiency disturbs myogenic progenitor cells function in postnatal skeletal muscle and we propose this as one of the causes of underdeveloped phenotype and myopathic characteristic of the TK2 deficient mice, in addition to the progressive mtDNA depletion, mitochondrial damage and respiratory chain deficiency in post-mitotic differentiated tissue.
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McCann KA, Williams DW, McKee EE. Metabolism of deoxypyrimidines and deoxypyrimidine antiviral analogs in isolated brain mitochondria. J Neurochem 2012; 122:126-37. [PMID: 22530558 DOI: 10.1111/j.1471-4159.2012.07765.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The goal of this project was to characterize deoxypyrimidine salvage pathways used to maintain deoxynucleoside triphosphate pools in isolated brain mitochondria and to determine the extent that antiviral pyrimidine analogs utilize or affect these pathways. Mitochondria from rat brains were incubated in media with labeled and unlabeled deoxynucleosides and deoxynucleoside analogs. Products were analyzed by HPLC coupled to an inline UV monitor and liquid scintillation counter. Isolated mitochondria transported thymidine and deoxycytidine into the matrix, and readily phosphorylated both of these to mono-, di-, and tri-phosphate nucleotides. Rates of phosphorylation were much higher than rates observed in mitochondria from heart and liver. Deoxyuridine was phosphorylated much more slowly than thymidine and only to dUMP. 3'-azido-3'-deoxythymidine, zidovudine (AZT), an antiviral thymidine analog, was phosphorylated to AZT-MP as readily as thymidine was phosphorylated to TMP, but little if any AZT-DP or AZT-TP was observed. AZT at 5.5 ± 1.7 μM was shown to inhibit thymidine phosphorylation by 50%, but was not observed to inhibit deoxycytidine phosphorylation except at levels > 100 μM. Stavudine and lamivudine were inert when incubated with isolated brain mitochondria. The kinetics of phosphorylation of thymidine, dC, and AZT were significantly different in brain mitochondria compared to mitochondria from liver and heart.
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Affiliation(s)
- Kathleen A McCann
- Indiana University School of Medicine - South Bend, South Bend, IN, USA.
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Horan MP, Pichaud N, Ballard JWO. Review: Quantifying Mitochondrial Dysfunction in Complex Diseases of Aging. ACTA ACUST UNITED AC 2012; 67:1022-35. [DOI: 10.1093/gerona/glr263] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Enzyme kinetics of the mitochondrial deoxyribonucleoside salvage pathway are not sufficient to support rapid mtDNA replication. PLoS Comput Biol 2011; 7:e1002078. [PMID: 21829339 PMCID: PMC3150320 DOI: 10.1371/journal.pcbi.1002078] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Accepted: 04/19/2011] [Indexed: 11/19/2022] Open
Abstract
Using a computational model, we simulated mitochondrial deoxynucleotide metabolism and mitochondrial DNA replication. Our results indicate that the output from the mitochondrial salvage enzymes alone is inadequate to support a mitochondrial DNA replication duration of as long as 10 hours. We find that an external source of deoxyribonucleoside diphosphates or triphosphates (dNTPs), in addition to those supplied by mitochondrial salvage, is essential for the replication of mitochondrial DNA to complete in the experimentally observed duration of approximately 1 to 2 hours. For meeting a relatively fast replication target of 2 hours, almost two-thirds of the dNTP requirements had to be externally supplied as either deoxyribonucleoside di- or triphosphates, at about equal rates for all four dNTPs. Added monophosphates did not suffice. However, for a replication target of 10 hours, mitochondrial salvage was able to provide for most, but not all, of the total substrate requirements. Still, additional dGTPs and dATPs had to be supplied. Our analysis of the enzyme kinetics also revealed that the majority of enzymes of this pathway prefer substrates that are not precursors (canonical deoxyribonucleosides and deoxyribonucleotides) for mitochondrial DNA replication, such as phosphorylated ribonucleotides, instead of the corresponding deoxyribonucleotides. The kinetic constants for reactions between mitochondrial salvage enzymes and deoxyribonucleotide substrates are physiologically unreasonable for achieving efficient catalysis with the expected in situ concentrations of deoxyribonucleotides. The powerhouses of human cells, mitochondria, contain DNA that is distinct from the primary genome, the DNA in the nucleus of cells. The mitochondrial genome needs to be replicated often to ensure continued generation of ATP (adenosine triphosphate) which is the energy currency of the cell. Problems with maintenance of mitochondrial DNA, arising from genetic mutations as well as from antiviral drugs, can lead to debilitating diseases that are often fatal in early life and childhood, or reduced compliance to therapy from patients suffering drug toxicity. It is therefore important to understand the processes that contribute to the upkeep of mitochondrial DNA. The activities of a set of enzymes, which together generate the chemical building blocks of mitochondrial DNA, are important in this regard. We used computational methods to analyze the properties of these enzymes. Results from our approach of treating these enzymes as a system rather than studying them one at a time suggest that in most conditions, the activities of the enzymes are not sufficient for completing replication of mitochondrial DNA in the observed duration of around 2 hours. We propose that a source of building blocks in addition to this set of enzymes appears to be essential.
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Bano D, Agostini M, Melino G, Nicotera P. Ageing, neuronal connectivity and brain disorders: an unsolved ripple effect. Mol Neurobiol 2011; 43:124-30. [PMID: 21234815 DOI: 10.1007/s12035-011-8164-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Accepted: 12/07/2010] [Indexed: 01/07/2023]
Abstract
Cognitive decline associated with ageing and age-related disorders emerges as one of the greatest health challenges in the next decades. To date, the molecular mechanisms underlying the onset of neuronal physiological changes in the central nervous system remain unclear. Functional MRI and PET studies have indicated the decline in working memory performance in older adults. Similarly, age-related disorders, such as Alzheimer's disease, are associated with changes in the prefontral cortex and related neural circuitry, which underlines the decline of integrative function between different brain regions. This is mainly attributed to the loss of synaptic connectivity, which is a feature commonly observed in neurodegenerative disorders. In humans, the morphological and functional changes in neurons, such as reduction of spine numbers and synaptic dysfunction, precede the first signs of cognitive decline and likely contribute to pathology progression. Thus, a new scenario emerges in which apparently unrelated diseases present common features, such as the remodelling of neuronal circuitries promoted by ageing. For many years, ageing was considered a process of slow deterioration triggered by accidental environmental factors. Conversely, it is now evident that ageing is a biological process tightly controlled by evolutionary highly conserved signalling pathways. Importantly, genetic mutations that enhance longevity significantly delay the loss of synaptic connectivity and, therefore, the onset of age-related brain disorders. Accordingly, tweaking ageing might be an attractive approach to prevent cognitive decline caused by age-related synaptic dysfunction.
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Affiliation(s)
- Daniele Bano
- Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Ludwig-Erhard-Allee 2, 53175, Bonn, Germany.
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Dorado B, Area E, Akman HO, Hirano M. Onset and organ specificity of Tk2 deficiency depends on Tk1 down-regulation and transcriptional compensation. Hum Mol Genet 2010; 20:155-64. [PMID: 20940150 PMCID: PMC3000681 DOI: 10.1093/hmg/ddq453] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Deficiency of thymidine kinase 2 (TK2) is a frequent cause of isolated myopathy or encephalomyopathy in children with mitochondrial DNA (mtDNA) depletion. To determine the bases of disease onset, organ specificity and severity of TK2 deficiency, we have carefully characterized Tk2 H126N knockin mice (Tk2-/-). Although normal until postnatal day 8, Tk2-/- mice rapidly develop fatal encephalomyopathy between postnatal days 10 and 13. We have observed that wild-type Tk2 activity is constant in the second week of life, while Tk1 activity decreases significantly between postnatal days 8 and 13. The down-regulation of Tk1 activity unmasks Tk2 deficiency in Tk2-/- mice and correlates with the onset of mtDNA depletion in the brain and the heart. Resistance to pathology in Tk2 mutant organs depends on compensatory mechanisms to the reduced mtDNA level. Our analyses at postnatal day 13 have revealed that Tk2-/- heart significantly increases mitochondrial transcript levels relative to the mtDNA content. This transcriptional compensation allows the heart to maintain normal levels of mtDNA-encoded proteins. The up-regulation in mitochondrial transcripts is not due to increased expression of the master mitochondrial biogenesis regulators peroxisome proliferator-activated receptor-gamma coactivator 1 alpha and nuclear respiratory factors 1 and 2, or to enhanced expression of the mitochondrial transcription factors A, B1 or B2. Instead, Tk2-/- heart compensates for mtDNA depletion by down-regulating the expression of the mitochondrial transcriptional terminator transcription factor 3 (MTERF3). Understanding the molecular mechanisms that allow Tk2 mutant organs to be spared may help design therapies for Tk2 deficiency.
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Affiliation(s)
- Beatriz Dorado
- Department of Neurology, Columbia University Medical Center, New York, NY 10032, USA
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