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Belostotsky R, Frishberg Y, Entelis N. Human mitochondrial tRNA quality control in health and disease: a channelling mechanism? RNA Biol 2012; 9:33-9. [PMID: 22258151 DOI: 10.4161/rna.9.1.18009] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Mutations in human mitochondrial tRNA genes are associated with a number of multisystemic disorders. These single nucleotide substitutions in various domains of tRNA molecules may affect different steps of tRNA biogenesis. Often, the prominent decrease of aminoacylation and/or steady-state levels of affected mitochondrial tRNA have been demonstrated in patients' tissues and in cultured cells. Similar effect has been observed for pathogenic mutations in nuclear genes encoding mitochondrial aminoacyl-tRNA-synthetases, while over-expression of mitochondrial aminoacyl-tRNA synthetases or elongation factor EF-Tu rescued mutated tRNAs from degradation. In this review we summarize experimental data concerning the possible regulatory mechanisms governing mitochondrial tRNA steady-state levels, and propose a hypothesis based on the tRNA channelling principle. According to this hypothesis, interaction of mitochondrial tRNA with proteins ensures not only tRNA synthesis, maturation and function, but also protection from degradation. Mutations perturbing this interaction lead to decreased tRNA stability.
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Affiliation(s)
- Ruth Belostotsky
- Division of Pediatric Nephrology, Shaare Zedek Medical Center; Jerusalem, Israel
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52
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Zeng A, Liu X, Shen L, Li W, Ding Z, Bai Y, Lu J. Analysis of mitochondrial DNA variations in a Chinese family with spinocerebellar ataxia. J Clin Neurosci 2011; 19:60-4. [PMID: 22169599 DOI: 10.1016/j.jocn.2011.05.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Revised: 05/03/2011] [Accepted: 05/06/2011] [Indexed: 11/25/2022]
Abstract
Mitochondrial dysfunction and mitochondrial DNA (mtDNA) variations have been shown to have a role in several neurological diseases. To determine whether there is an association between mtDNA variations and spinocerebellar ataxia (SCA), we analyzed the mtDNA main control region (D-loop), as well as mtDNA content and the prevalence of the common deletion, in blood samples from members of a large Chinese family (14 individuals with SCA and 13 healthy individuals). All 14 individuals with SCA were genotyped as SCA3. Thirteen mtDNA haplotypes were identified among the 27 subjects. We detected no mutations in the mtDNA D-loop region and found no significant differences in mtDNA copy number or common deletion level between patients and their healthy relatives. Contrary to some previous reports, our study showed that mtDNA variations seem to be a rare event in individuals with SCA3.
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Affiliation(s)
- Aiping Zeng
- Wenling Hospital of Wenzhou Medical College, Wenling, Zhejiang, China
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53
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Adhya S, Mahato B, Jash S, Koley S, Dhar G, Chowdhury T. Mitochondrial gene therapy: The tortuous path from bench to bedside. Mitochondrion 2011; 11:839-44. [DOI: 10.1016/j.mito.2011.06.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Revised: 05/12/2011] [Accepted: 06/10/2011] [Indexed: 01/25/2023]
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54
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Wang G, Shimada E, Koehler CM, Teitell MA. PNPASE and RNA trafficking into mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2011; 1819:998-1007. [PMID: 22023881 DOI: 10.1016/j.bbagrm.2011.10.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Revised: 09/26/2011] [Accepted: 10/07/2011] [Indexed: 10/16/2022]
Abstract
The mitochondrial genome encodes a very small fraction of the macromolecular components that are required to generate functional mitochondria. Therefore, most components are encoded within the nuclear genome and are imported into mitochondria from the cytosol. Understanding how mitochondria are assembled, function, and dysfunction in diseases requires detailed knowledge of mitochondrial import mechanisms and pathways. The import of nucleus-encoded RNAs is required for mitochondrial biogenesis and function, but unlike pre-protein import, the pathways and cellular machineries of RNA import are poorly defined, especially in mammals. Recent studies have shown that mammalian polynucleotide phosphorylase (PNPASE) localizes in the mitochondrial intermembrane space (IMS) to regulate the import of RNA. The identification of PNPASE as the first component of the RNA import pathway, along with a growing list of nucleus-encoded RNAs that are imported and newly developed assay systems for RNA import studies, suggest a unique opportunity is emerging to identify the factors and mechanisms that regulate RNA import into mammalian mitochondria. Here we summarize what is known in this fascinating area of mitochondrial biogenesis, identify areas that require further investigation, and speculate on the impact unraveling RNA import mechanisms and pathways will have for the field going forward. This article is part of a Special Issue entitled: Mitochondrial Gene Expression.
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Affiliation(s)
- Geng Wang
- Department of Chemistry and Biochemistry, University of California at Los Angeles, Los Angeles, CA 90095, USA
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55
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Abstract
The mitochondrial genomes of most eukaryotes lack a variable number of tRNA genes. This lack is compensated for by import of a small fraction of the corresponding cytosolic tRNAs. There are two broad mechanisms for the import of tRNAs into mitochondria. In the first one, the tRNA is coimported together with a mitochondrial precursor protein along the protein import pathway. It applies to the yeast tRNA(Lys) and has been elucidated in great detail. In the second more vaguely defined mechanism, which is mainly found in plants and protozoa, tRNAs are directly imported independent of cytosolic factors. However, results in plants indicate that direct import of tRNAs may nevertheless require some components of the protein import machinery. All imported tRNAs in all systems are of the eukaryotic type but need to be functionally integrated into the mitochondrial translation system of bacterial descent. For some tRNAs, this is not trivial and requires unique evolutionary adaptations.
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Affiliation(s)
- André Schneider
- Department of Chemistry and Biochemistry, University of Bern, CH-3012 Bern, Switzerland.
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56
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Smirnov A, Entelis N, Martin RP, Tarassov I. Biological significance of 5S rRNA import into human mitochondria: role of ribosomal protein MRP-L18. Genes Dev 2011; 25:1289-305. [PMID: 21685364 DOI: 10.1101/gad.624711] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
5S rRNA is an essential component of ribosomes of all living organisms, the only known exceptions being mitochondrial ribosomes of fungi, animals, and some protists. An intriguing situation distinguishes mammalian cells: Although the mitochondrial genome contains no 5S rRNA genes, abundant import of the nuclear DNA-encoded 5S rRNA into mitochondria was reported. Neither the detailed mechanism of this pathway nor its rationale was clarified to date. In this study, we describe an elegant molecular conveyor composed of a previously identified human 5S rRNA import factor, rhodanese, and mitochondrial ribosomal protein L18, thanks to which 5S rRNA molecules can be specifically withdrawn from the cytosolic pool and redirected to mitochondria, bypassing the classic nucleolar reimport pathway. Inside mitochondria, the cytosolic 5S rRNA is shown to be associated with mitochondrial ribosomes.
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Affiliation(s)
- Alexandre Smirnov
- "Génétique Moléculaire, Génomique, Microbiologie" (GMGM), Université de Strasbourg-CNRS, France
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57
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Rubio MAT, Hopper AK. Transfer RNA travels from the cytoplasm to organelles. WILEY INTERDISCIPLINARY REVIEWS-RNA 2011; 2:802-17. [PMID: 21976284 DOI: 10.1002/wrna.93] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Transfer RNAs (tRNAs) encoded by the nuclear genome are surprisingly dynamic. Although tRNAs function in protein synthesis occurring on cytoplasmic ribosomes, tRNAs can transit from the cytoplasm to the nucleus and then again return to the cytoplasm by a process known as the tRNA retrograde process. Subsets of the cytoplasmic tRNAs are also imported into mitochondria and function in mitochondrial protein synthesis. The numbers of tRNA species that are imported into mitochondria differ among organisms, ranging from just a few to the entire set needed to decode mitochondrially encoded mRNAs. For some tRNAs, import is dependent on the mitochondrial protein import machinery, whereas the majority of tRNA mitochondrial import is independent of this machinery. Although cytoplasmic proteins and proteins located on the mitochondrial surface participating in the tRNA import process have been described for several organisms, the identity of these proteins differ among organisms. Likewise, the tRNA determinants required for mitochondrial import differ among tRNA species and organisms. Here, we present an overview and discuss the current state of knowledge regarding the mechanisms involved in the tRNA retrograde process and continue with an overview of tRNA import into mitochondria. Finally, we highlight areas of future research to understand the function and regulation of movement of tRNAs between the cytoplasm and organelles.
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Affiliation(s)
- Mary Anne T Rubio
- Department of Microbiology and Center for RNA Biology, Ohio State University, Columbus, OH 43210, USA
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58
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Karicheva OZ, Kolesnikova OA, Schirtz T, Vysokikh MY, Mager-Heckel AM, Lombès A, Boucheham A, Krasheninnikov IA, Martin RP, Entelis N, Tarassov I. Correction of the consequences of mitochondrial 3243A>G mutation in the MT-TL1 gene causing the MELAS syndrome by tRNA import into mitochondria. Nucleic Acids Res 2011; 39:8173-86. [PMID: 21724600 PMCID: PMC3185436 DOI: 10.1093/nar/gkr546] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Mutations in human mitochondrial DNA are often associated with incurable human neuromuscular diseases. Among these mutations, an important number have been identified in tRNA genes, including 29 in the gene MT-TL1 coding for the tRNALeu(UUR). The m.3243A>G mutation was described as the major cause of the MELAS syndrome (mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes). This mutation was reported to reduce tRNALeu(UUR) aminoacylation and modification of its anti-codon wobble position, which results in a defective mitochondrial protein synthesis and reduced activities of respiratory chain complexes. In the present study, we have tested whether the mitochondrial targeting of recombinant tRNAs bearing the identity elements for human mitochondrial leucyl-tRNA synthetase can rescue the phenotype caused by MELAS mutation in human transmitochondrial cybrid cells. We demonstrate that nuclear expression and mitochondrial targeting of specifically designed transgenic tRNAs results in an improvement of mitochondrial translation, increased levels of mitochondrial DNA-encoded respiratory complexes subunits, and significant rescue of respiration. These findings prove the possibility to direct tRNAs with changed aminoacylation specificities into mitochondria, thus extending the potential therapeutic strategy of allotopic expression to address mitochondrial disorders.
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Affiliation(s)
- Olga Z Karicheva
- UMR 7156 University of Strasbourg - CNRS, Molecular Genetics, Genomics & Microbiology, Strasbourg 67084, France
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59
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Barrey E, Saint-Auret G, Bonnamy B, Damas D, Boyer O, Gidrol X. Pre-microRNA and mature microRNA in human mitochondria. PLoS One 2011; 6:e20220. [PMID: 21637849 PMCID: PMC3102686 DOI: 10.1371/journal.pone.0020220] [Citation(s) in RCA: 224] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Accepted: 04/27/2011] [Indexed: 01/15/2023] Open
Abstract
Background Because of the central functions of the mitochondria in providing metabolic energy and initiating apoptosis on one hand and the role that microRNA (miRNA) play in gene expression, we hypothesized that some miRNA could be present in the mitochondria for post-transcriptomic regulation by RNA interference. We intend to identify miRNA localized in the mitochondria isolated from human skeletal primary muscular cells. Methodology/Principal Findings To investigate the potential origin of mitochondrial miRNA, we in-silico searched for microRNA candidates in the mtDNA. Twenty five human pre-miRNA and 33 miRNA aligments (E-value<0.1) were found in the reference mitochondrial sequence and some of the best candidates were chosen for a co-localization test. In situ hybridization of pre-mir-302a, pre-let-7b and mir-365, using specific labelled locked nucleic acids and confocal microscopy, demonstrated that these miRNA were localized in mitochondria of human myoblasts. Total RNA was extracted from enriched mitochondria isolated by an immunomagnetic method from a culture of human myotubes. The detection of 742 human miRNA (miRBase) were monitored by RT-qPCR at three increasing mtRNA inputs. Forty six miRNA were significantly expressed (2nd derivative method Cp>35) for the smallest RNA input concentration and 204 miRNA for the maximum RNA input concentration. In silico analysis predicted 80 putative miRNA target sites in the mitochondrial genome (E-value<0.05). Conclusions/Significance The present study experimentally demonstrated for the first time the presence of pre-miRNA and miRNA in the human mitochondria isolated from skeletal muscular cells. A set of miRNA were significantly detected in mitochondria fraction. The origin of these pre-miRNA and miRNA should be further investigate to determine if they are imported from the cytosol and/or if they are partially processed in the mitochondria.
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Affiliation(s)
- Eric Barrey
- Unité de Biologie Intégrative des Adaptations à l'Exercice – INSERM U902, Genopole Evry, France
- Biopuces et Génomique Fonctionnelle (Biomics), Direction des Sciences du Vivant, CEA, Grenoble, France
- * E-mail: (EB); (XG)
| | - Gaelle Saint-Auret
- Biopuces et Génomique Fonctionnelle (Biomics), Direction des Sciences du Vivant, CEA, Grenoble, France
| | - Blandine Bonnamy
- Unité de Biologie Intégrative des Adaptations à l'Exercice – INSERM U902, Genopole Evry, France
| | - Dominique Damas
- Unité de Biologie Intégrative des Adaptations à l'Exercice – INSERM U902, Genopole Evry, France
| | - Orane Boyer
- Unité de Biologie Intégrative des Adaptations à l'Exercice – INSERM U902, Genopole Evry, France
| | - Xavier Gidrol
- Biopuces et Génomique Fonctionnelle (Biomics), Direction des Sciences du Vivant, CEA, Grenoble, France
- * E-mail: (EB); (XG)
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60
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Sieber F, Placido A, El Farouk-Ameqrane S, Duchêne AM, Maréchal-Drouard L. A protein shuttle system to target RNA into mitochondria. Nucleic Acids Res 2011; 39:e96. [PMID: 21596779 PMCID: PMC3152368 DOI: 10.1093/nar/gkr380] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Mitochondria play a key role in essential cellular functions. A deeper understanding of mitochondrial molecular processes is hampered by the difficulty of incorporating foreign nucleic acids into organelles. Mitochondria of most eukaryotic species import cytosolic tRNAs. Based on this natural process, we describe here a powerful shuttle system to internalize several types of RNAs into isolated mitochondria. We demonstrate that this tool is useful to investigate tRNA processing or mRNA editing in plant mitochondria. Furthermore, we show that the same strategy can be used to address both tRNA and mRNA to isolated mammalian mitochondria. We anticipate our novel approach to be the starting point for various studies on mitochondrial processes. Finally, our study provides new insights into the mechanism of RNA import into mitochondria.
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Affiliation(s)
- François Sieber
- Institut de Biologie Moléculaire des Plantes, UPR 2357-CNRS, Université de Strasbourg, 12 rue du Général Zimmer, F-67084 Strasbourg Cedex, France
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61
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Cwerman-Thibault H, Sahel JA, Corral-Debrinski M. Mitochondrial medicine: to a new era of gene therapy for mitochondrial DNA mutations. J Inherit Metab Dis 2011; 34:327-44. [PMID: 20571866 DOI: 10.1007/s10545-010-9131-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2010] [Revised: 05/12/2010] [Accepted: 05/17/2010] [Indexed: 01/01/2023]
Abstract
Mitochondrial disorders can no longer be ignored in most medical disciplines. Such disorders include specific and widespread organ involvement, with tissue degeneration or tumor formation. Primary or secondary actors, mitochondrial dysfunctions also play a role in the aging process. Despite progresses made in identification of their molecular bases, nearly everything remains to be done as regards therapy. Research dealing with mitochondrial physiology and pathology has >20 years of history around the world. We are involved, as are many other laboratories, in the challenge of finding ways to fight these diseases. However, our main limitation is the scarcety of animal models required for both understanding the molecular mechanisms underlying the diseases and evaluating therapeutic strategies. This is especially true for diseases due to mutations in mitochondrial DNA (mtDNA), since an authentic genetic model of mtDNA mutations is technically a very difficult task due to both the inability of manipulating the mitochondrial genome of living mammalian cells and to its multicopy nature. This has led researchers in the field to consider the prospect of gene therapy approaches that can roughly be divided into three groups: (1) import of wild-type copies or relevant sections of DNA or RNA into mitochondria, (2) manipulation of mitochondrial genetic content, and (3) rescue of a defect by expression of an engineered gene product from the nucleus (allotopic or xenotropic expression). We briefly introduce these concepts and indicate where promising progress has been made in the last decade.
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62
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RNA-mediated restoration of mitochondrial function in cells harboring a Kearns Sayre Syndrome mutation. Mitochondrion 2011; 11:564-74. [PMID: 21406250 DOI: 10.1016/j.mito.2011.03.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Accepted: 03/03/2011] [Indexed: 11/20/2022]
Abstract
Mutations in mitochondrial DNA (mtDNA) generate multi-system disorders due to failure of ATP production. A cybrid containing a 1.9-kb mtDNA deletion from a patient with Kearns Sayre Syndrome is respiration-defective and grows glycolytically. When treated with a ribonucleoprotein (RNP) complex of polycistronic RNA 1 (pcRNA1) containing mtDNA-encoded genes and a multi-subunit carrier complex R8, full-length pcRNA1 was transported to mitochondria. Translation of the pcRNA1-encoded mRNAs was observed in mitochondria from RNP-treated cells. Respiration of the cybrid was rescued to approximately 90% of normal within hours, switching the cells to aerobic growth. These findings have implications for the development of effective mitochondrial gene therapy.
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63
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Abstract
Mitochondria are ubiquitous and essential organelles for all nucleated cells of higher eukaryotes. They contain their own genome [mtDNA (mitochondrial DNA)], and this autosomally replicating extranuclear DNA encodes a complement of genes whose products are required to couple oxidative phosphorylation. Sequencing of this human mtDNA more than 20 years ago revealed unusual features that included a modified codon usage. Specific deviations from the standard genetic code include recoding of the conventional UGA stop to tryptophan, and, strikingly, the apparent recoding of two arginine triplets (AGA and AGG) to termination signals. This latter reassignment was made because of the absence of cognate mtDNA-encoded tRNAs, and a lack of tRNAs imported from the cytosol. Each of these codons only occurs once and, in both cases, at the very end of an open reading frame. The presence of both AGA and AGG is rarely found in other mammals, and the molecular mechanism that has driven the change from encoding arginine to dictating a translational stop has posed a challenging conundrum. Mitochondria from the majority of other organisms studied use only UAA and UAG, leaving the intriguing question of why human organelles appear to have added the complication of a further two stop codons, AGA and AGG, or have they? In the present review, we report recent data to show that mammalian mitochondria can utilize a -1 frameshift such that only the standard UAA and UAG stop codons are required to terminate the synthesis of all 13 polypeptides.
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64
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Wenz T, Williams SL, Bacman SR, Moraes CT. Emerging therapeutic approaches to mitochondrial diseases. ACTA ACUST UNITED AC 2011; 16:219-29. [PMID: 20818736 DOI: 10.1002/ddrr.109] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Mitochondrial diseases are very heterogeneous and can affect different tissues and organs. Moreover, they can be caused by genetic defects in either nuclear or mitochondrial DNA as well as by environmental factors. All of these factors have made the development of therapies difficult. In this review article, we will discuss emerging approaches to the therapy of mitochondrial disorders, some of which are targeted to specific conditions whereas others may be applicable to a more diverse group of patients.
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Affiliation(s)
- Tina Wenz
- Department of Neurology, University of Miami School of Medicine, 1095 NW 14th Terrace, Miami, FL 33136, USA
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65
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Mitochondrial RNA import: from diversity of natural mechanisms to potential applications. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2011; 287:145-90. [PMID: 21414588 DOI: 10.1016/b978-0-12-386043-9.00004-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mitochondria, owing to their bacterial origin, still contain their own DNA. However, the majority of bacterial genes were lost or transferred to the nuclear genome and the biogenesis of the "present-day" mitochondria mainly depends on the expression of the nuclear genome. Thus, most mitochondrial proteins and a small number of mitochondrial RNAs (mostly tRNAs) expressed from nuclear genes need to be imported into the organelle. During evolution, macromolecule import systems were universally established. The processes of protein mitochondrial import are very well described in the literature. By contrast, deciphering the mitochondrial RNA import phenomenon is still a real challenge. The purpose of this review is to present a general survey of our present knowledge in this field in different model organisms, protozoa, plants, yeast, and mammals. Questions still under debate and major challenges are discussed. Mitochondria are involved in numerous human diseases. The targeting of macromolecule to mitochondria represents a promising way to fight mitochondrial disorders and recent developments in this area of research are presented.
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66
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Nesbitt V, Whittaker RG, Turnbull DM, McFarland R, Taylor RW. mtDNA disease for the neurologist. FUTURE NEUROLOGY 2011. [DOI: 10.2217/fnl.10.70] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Inherited and acquired mutations of mtDNA cause an extraordinary group of diseases that are associated with a diverse panoply of neurological and non-neurological features. These diseases are surprisingly common and are often severely debilitating and readily transmitted through families. Remarkable advances in understanding molecular mechanisms have been made since the first pathogenic mtDNA mutations were identified in 1988, and while widely available genetic techniques have facilitated diagnosis, the complexities of mitochondrial genetics leave the neurologist facing important challenges in recognizing, managing and counseling patients with mtDNA mutations. In this article, we will discuss the clinical phenotypes associated with mtDNA disease, current diagnostic strategies, disease management and genetic counseling, as well as presenting new developments in preventing disease transmission and secondary complications.
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Affiliation(s)
- Victoria Nesbitt
- Mitochondrial Research Group, Institute for Ageing & Health, The Medical School, Newcastle University, Framlington Place, Newcastle-upon-Tyne, NE2 4HH, UK
| | - Roger G Whittaker
- Mitochondrial Research Group, Institute for Ageing & Health, The Medical School, Newcastle University, Framlington Place, Newcastle-upon-Tyne, NE2 4HH, UK
| | - Douglass M Turnbull
- Mitochondrial Research Group, Institute for Ageing & Health, The Medical School, Newcastle University, Framlington Place, Newcastle-upon-Tyne, NE2 4HH, UK
| | - Robert McFarland
- Mitochondrial Research Group, Institute for Ageing & Health, The Medical School, Newcastle University, Framlington Place, Newcastle-upon-Tyne, NE2 4HH, UK
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67
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Mazunin IO, Volodko NV, Starikovskaya EB, Sukernik RI. Mitochondrial genome and human mitochondrial diseases. Mol Biol 2010. [DOI: 10.1134/s0026893310050018] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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68
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Wang G, Chen HW, Oktay Y, Zhang J, Allen EL, Smith GM, Fan KC, Hong JS, French SW, McCaffery JM, Lightowlers RN, Morse HC, Koehler CM, Teitell MA. PNPASE regulates RNA import into mitochondria. Cell 2010; 142:456-67. [PMID: 20691904 DOI: 10.1016/j.cell.2010.06.035] [Citation(s) in RCA: 260] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Revised: 03/20/2010] [Accepted: 05/13/2010] [Indexed: 02/04/2023]
Abstract
RNA import into mammalian mitochondria is considered essential for replication, transcription, and translation of the mitochondrial genome but the pathway(s) and factors that control this import are poorly understood. Previously, we localized polynucleotide phosphorylase (PNPASE), a 3' --> 5' exoribonuclease and poly-A polymerase, in the mitochondrial intermembrane space, a location lacking resident RNAs. Here, we show a new role for PNPASE in regulating the import of nuclear-encoded RNAs into the mitochondrial matrix. PNPASE reduction impaired mitochondrial RNA processing and polycistronic transcripts accumulated. Augmented import of RNase P, 5S rRNA, and MRP RNAs depended on PNPASE expression and PNPASE-imported RNA interactions were identified. PNPASE RNA processing and import activities were separable and a mitochondrial RNA targeting signal was isolated that enabled RNA import in a PNPASE-dependent manner. Combined, these data strongly support an unanticipated role for PNPASE in mediating the translocation of RNAs into mitochondria.
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Affiliation(s)
- Geng Wang
- Department of Chemistry and Biochemistry, University of California at Los Angeles, Los Angeles, CA 90095, USA
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69
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Smirnov A, Comte C, Mager-Heckel AM, Addis V, Krasheninnikov IA, Martin RP, Entelis N, Tarassov I. Mitochondrial enzyme rhodanese is essential for 5 S ribosomal RNA import into human mitochondria. J Biol Chem 2010; 285:30792-803. [PMID: 20663881 DOI: 10.1074/jbc.m110.151183] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
5 S rRNA is an essential component of ribosomes. In eukaryotic cells, it is distinguished by particularly complex intracellular traffic, including nuclear export and re-import. The finding that in mammalian cells 5 S rRNA can eventually escape its usual circuit toward nascent ribosomes to get imported into mitochondria has made the scheme more complex, and it has raised questions about both the mechanism of 5 S rRNA mitochondrial targeting and its function inside the organelle. Previously, we showed that import of 5 S rRNA into mitochondria requires unknown cytosolic proteins. Here, one of them was identified as mitochondrial thiosulfate sulfurtransferase, rhodanese. Rhodanese in its misfolded form was found to possess a strong and specific 5 S rRNA binding activity, exploiting sites found earlier to function as signals of 5 S rRNA mitochondrial localization. The interaction with 5 S rRNA occurs cotranslationally and results in formation of a stable complex in which rhodanese is preserved in a compact enzymatically inactive conformation. Human 5 S rRNA in a branched Mg(2+)-free form, upon its interaction with misfolded rhodanese, demonstrates characteristic functional traits of Hsp40 cochaperones implicated in mitochondrial precursor protein targeting, suggesting that it may use this mechanism to ensure its own mitochondrial localization. Finally, silencing of the rhodanese gene caused not only a proportional decrease of 5 S rRNA import but also a general inhibition of mitochondrial translation, indicating the functional importance of the imported 5 S rRNA inside the organelle.
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Affiliation(s)
- Alexandre Smirnov
- Department of Molecular and Cellular Genetics, UMR 7156, CNRS-University of Strasbourg, Strasbourg 67084, France
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70
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Shokolenko IN, Alexeyev MF, LeDoux SP, Wilson GL. The approaches for manipulating mitochondrial proteome. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2010; 51:451-461. [PMID: 20544885 PMCID: PMC3249350 DOI: 10.1002/em.20570] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Over the past decade a large volume of research data has accumulated which has established a fundamental role for mitochondria in normal cellular functioning, as well as in various pathologies. Mitochondria play a pivotal role in metabolism and energy production, and are one of the key players involved in programmed cell death. On the other hand, mitochondrial dysfunction is implicated, directly or indirectly in numerous pathological conditions including inherited mitochondrial disorders, diabetes, cardiovascular and neurodegenerative diseases, and a variety of malignancies. The ability to modulate mitochondrial function by altering the diverse protein component of this organelle may be of great value for developing future therapeutic interventions. This review will discuss approaches used to introduce proteins into mitochondria. One group of methods utilizes strategies aimed at expressing proteins from genes in the nucleus. These include overexpression of nuclear-encoded mitochondrial proteins, allotopic expression, which is the re-coding and relocation of mitochondrial genes to the nucleus for expression and subsequent delivery of their gene products to mitochondria, and xenotopic expression, which is the nuclear expression of genes coding electron transport chain components from distant species, for delivery of their products to mammalian mitochondria. Additionally, antigenomic and progenomic strategies which focus on expression of mitochondrially targeted nuclear proteins involved in the maintenance of mtDNA will be discussed. The second group of methods considered will focus on attempts to use purified proteins for mitochondrial delivery. Special consideration has been given to the complexities involved in targeting exogenous proteins to mitochondria.
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71
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Kolesnikova O, Kazakova H, Comte C, Steinberg S, Kamenski P, Martin RP, Tarassov I, Entelis N. Selection of RNA aptamers imported into yeast and human mitochondria. RNA (NEW YORK, N.Y.) 2010; 16:926-941. [PMID: 20348443 PMCID: PMC2856887 DOI: 10.1261/rna.1914110] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2009] [Accepted: 02/01/2010] [Indexed: 05/29/2023]
Abstract
In the yeast Saccharomyces cerevisiae, nuclear DNA-encoded is partially imported into mitochondria. We previously found that the synthetic transcripts of yeast tRNA(Lys) and a number of their mutant versions could be specifically internalized by isolated yeast and human mitochondria. The mitochondrial targeting of tRNA(Lys) in yeast was shown to depend on the cytosolic precursor of mitochondrial lysyl-tRNA synthetase and the glycolytic enzyme enolase. Here we applied the approach of in vitro selection (SELEX) to broaden the spectrum of importable tRNA-derived molecules. We found that RNAs selected for their import into isolated yeast mitochondria have lost the potential to acquire a classical tRNA-shape. Analysis of conformational rearrangements in the importable RNAs by in-gel fluorescence resonance energy transfer (FRET) approach permitted us to suggest that protein factor binding and subsequent import require formation of an alternative structure, different from a classic L-form tRNA model. We show that in the complex with targeting protein factor, enolase 2, tRK1 adopts a particular conformation characterized by bringing together the 3'-end and the TPsiC loop. This is a first evidence for implication of RNA secondary structure rearrangement in the mechanism of mitochondrial import selectivity. Based on these data, a set of small RNA molecules with significantly improved efficiency of import into yeast and human mitochondria was constructed, opening the possibility of creating a new mitochondrial vector system able to target therapeutic oligoribonucleotides into deficient human mitochondria.
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MESH Headings
- Aptamers, Nucleotide/chemistry
- Aptamers, Nucleotide/genetics
- Aptamers, Nucleotide/metabolism
- Base Sequence
- Biological Transport, Active
- Fluorescence Resonance Energy Transfer
- Humans
- In Vitro Techniques
- Lysine-tRNA Ligase/metabolism
- Mitochondria/metabolism
- Models, Molecular
- Molecular Sequence Data
- Nucleic Acid Conformation
- Phosphopyruvate Hydratase/metabolism
- RNA, Fungal/genetics
- RNA, Fungal/metabolism
- RNA, Transfer, Amino Acyl/genetics
- RNA, Transfer, Amino Acyl/metabolism
- SELEX Aptamer Technique
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/metabolism
- Sequence Homology, Nucleic Acid
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Affiliation(s)
- Olga Kolesnikova
- UMR 7156, Université de Strasbourg/Centre National de la Recherche Scientifique (UdS/CNRS), 67084 Strasbourg, France
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72
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Wallace DC, Fan W, Procaccio V. Mitochondrial energetics and therapeutics. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2010; 5:297-348. [PMID: 20078222 DOI: 10.1146/annurev.pathol.4.110807.092314] [Citation(s) in RCA: 496] [Impact Index Per Article: 35.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Mitochondrial dysfunction has been linked to a wide range of degenerative and metabolic diseases, cancer, and aging. All these clinical manifestations arise from the central role of bioenergetics in cell biology. Although genetic therapies are maturing as the rules of bioenergetic genetics are clarified, metabolic therapies have been ineffectual. This failure results from our limited appreciation of the role of bioenergetics as the interface between the environment and the cell. A systems approach, which, ironically, was first successfully applied over 80 years ago with the introduction of the ketogenic diet, is required. Analysis of the many ways that a shift from carbohydrate glycolytic metabolism to fatty acid and ketone oxidative metabolism may modulate metabolism, signal transduction pathways, and the epigenome gives us an appreciation of the ketogenic diet and the potential for bioenergetic therapeutics.
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Affiliation(s)
- Douglas C Wallace
- Center for Molecular and Mitochondrial Medicine and Genetics and Departments of Biological Chemistry, Ecology and Evolutionary Biology, and Pediatrics, University of California at Irvine, Irvine, California 92697-3940, USA.
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73
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tRNA mitochondrial import in yeast: Mapping of the import determinants in the carrier protein, the precursor of mitochondrial lysyl-tRNA synthetase. Mitochondrion 2010; 10:284-93. [PMID: 20064631 DOI: 10.1016/j.mito.2010.01.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2009] [Revised: 12/05/2009] [Accepted: 01/05/2010] [Indexed: 02/03/2023]
Abstract
Mitochondria of many species import of nuclear DNA-encoded tRNAs. This widely spread but poorly studied phenomenon proved to be a promising tool for mitochondrial transfection. In yeast Saccharomyces cerevisiae, one cytosolic tRNAs(Lys) is partially targeted into mitochondria. Previous studies have shown that binding of this tRNA to its putative protein carrier, the precursor of mitochondrial lysyl-tRNA synthetase (preMsk1p), IIb class aminoacyl-tRNA synthetase, was a pre-requisite of import. In this work, we identify the hinge region with two adjacent helices H5 and H7 to be responsible for mitochondrial targeting of the tRNA and characterize preMsk1p versions with altered tRK1 import capacities.
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74
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Turnbull HE, Lax NZ, Diodato D, Ansorge O, Turnbull DM. The mitochondrial brain: From mitochondrial genome to neurodegeneration. BIOCHIMICA ET BIOPHYSICA ACTA 2010; 1802:111-21. [PMID: 19647794 PMCID: PMC2795853 DOI: 10.1016/j.bbadis.2009.07.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Revised: 07/21/2009] [Accepted: 07/23/2009] [Indexed: 11/26/2022]
Abstract
Mitochondrial DNA mutations are an important cause of neurological disease. The clinical presentation is very varied in terms of age of onset and different neurological signs and symptoms. The clinical course varies considerably but in many patients there is a progressive decline, and in some evidence of marked neurodegeneration. Our understanding of the mechanisms involved is limited due in part to limited availability of animal models of disease. However, studies on human post-mortem brains, combined with clinical and radiological studies, are giving important insights into specific neuronal involvement.
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Affiliation(s)
- Helen E Turnbull
- Mitochondrial Research Group, Institute for Ageing and Health, Newcastle University, NE24HH, UK.
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75
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Mitochondrial DNA mutations and human disease. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1797:113-28. [PMID: 19761752 DOI: 10.1016/j.bbabio.2009.09.005] [Citation(s) in RCA: 417] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2009] [Revised: 09/04/2009] [Accepted: 09/09/2009] [Indexed: 01/07/2023]
Abstract
Mitochondrial disorders are a group of clinically heterogeneous diseases, commonly defined by a lack of cellular energy due to oxidative phosphorylation (OXPHOS) defects. Since the identification of the first human pathological mitochondrial DNA (mtDNA) mutations in 1988, significant efforts have been spent in cataloguing the vast array of causative genetic defects of these disorders. Currently, more than 250 pathogenic mtDNA mutations have been identified. An ever-increasing number of nuclear DNA mutations are also being reported as the majority of proteins involved in mitochondrial metabolism and maintenance are nuclear-encoded. Understanding the phenotypic diversity and elucidating the molecular mechanisms at the basis of these diseases has however proved challenging. Progress has been hampered by the peculiar features of mitochondrial genetics, an inability to manipulate the mitochondrial genome, and difficulties in obtaining suitable models of disease. In this review, we will first outline the unique features of mitochondrial genetics before detailing the diseases and their genetic causes, focusing specifically on primary mtDNA genetic defects. The functional consequences of mtDNA mutations that have been characterised to date will also be discussed, along with current and potential future diagnostic and therapeutic advances.
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76
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Egli RJ, Southam L, Wilkins JM, Lorenzen I, Pombo-Suarez M, Gonzalez A, Carr A, Chapman K, Loughlin J. Functional analysis of the osteoarthritis susceptibility-associated GDF5 regulatory polymorphism. ACTA ACUST UNITED AC 2009; 60:2055-64. [PMID: 19565498 DOI: 10.1002/art.24616] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Single-nucleotide polymorphism (SNP) rs143383 (T to C) in the 5'-untranslated region (5'-UTR) of GDF5 has recently been reported to be associated with osteoarthritis (OA) susceptibility, with lower expression of the risk-associated T allele observed in vitro and in vivo. The in vivo studies were performed on cartilage tissue from OA patients. The present study was undertaken to expand the analysis of the effect of this SNP on GDF5 allelic expression to more joint tissue types, to investigate for cis and trans factors that interact with the SNP, and to examine novel cis-acting GDF5 regulatory polymorphisms. METHODS Tissue samples were collected from OA patients undergoing joint replacement of the hip or knee. Nucleic acid was extracted, and, using rs143383 and an assay that discriminates and quantifies allelic expression, the relative amount of GDF5 expression from the T and C alleles was measured. Additional common variants in the GDF5 transcript sequence were interrogated as potential regulatory elements using allelic expression and luciferase reporter assays, and electrophoretic mobility shift assays were used to search for trans factors binding to rs143383. RESULTS We observed a consistent allelic expression imbalance of GDF5 in all tissues tested, implying that the functional effect mediated by rs143383 on GDF5 expression is joint-wide. We identified a second polymorphism, located in the 3'-UTR of GDF5, that influenced allelic expression of the gene independent of rs143383. Finally, we observed differential binding of deformed epidermal autoregulatory factor 1 (DEAF-1) to the 2 alleles of rs143383. CONCLUSION These findings show that the OA susceptibility mediated by polymorphism in GDF5 is not restricted to cartilage, emphasizing the need to consider the disease as involving the whole joint. The existence of an additional cis-acting regulatory polymorphism highlights the complexity of the regulation of expression of this important OA susceptibility locus. DEAF-1 is a trans-acting factor that merits further investigation as a potential tool for modulating GDF5 expression.
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77
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Zeharia A, Shaag A, Pappo O, Mager-Heckel AM, Saada A, Beinat M, Karicheva O, Mandel H, Ofek N, Segel R, Marom D, Rötig A, Tarassov I, Elpeleg O. Acute infantile liver failure due to mutations in the TRMU gene. Am J Hum Genet 2009; 85:401-7. [PMID: 19732863 DOI: 10.1016/j.ajhg.2009.08.004] [Citation(s) in RCA: 162] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2009] [Revised: 08/04/2009] [Accepted: 08/06/2009] [Indexed: 11/30/2022] Open
Abstract
Acute liver failure in infancy accompanied by lactic acidemia was previously shown to result from mtDNA depletion. We report on 13 unrelated infants who presented with acute liver failure and lactic acidemia with normal mtDNA content. Four died during the acute episodes, and the survivors never had a recurrence. The longest follow-up period was 14 years. Using homozygosity mapping, we identified mutations in the TRMU gene, which encodes a mitochondria-specific tRNA-modifying enzyme, tRNA 5-methylaminomethyl-2-thiouridylate methyltransferase. Accordingly, the 2-thiouridylation levels of the mitochondrial tRNAs were markedly reduced. Given that sulfur is a TRMU substrate and its availability is limited during the neonatal period, we propose that there is a window of time whereby patients with TRMU mutations are at increased risk of developing liver failure.
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Affiliation(s)
- Avraham Zeharia
- Department of Human Genetics and Metabolic Diseases, Hadassah, the Hebrew University Medical Center, Jerusalem, Israel
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78
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Abstract
Research of patients with defects in cellular energy metabolism (mitochondrial disease) has led to a better understanding of mitochondrial biology in health and disease. The obtained knowledge is of increasing importance for physicians of all medical disciplines. It assists in enabling the development of rational treatment strategies for diseases or conditions caused by mitochondrial dysfunction. The still frequently used classical interventions with vitamins or co-factors are only beneficial in some rare mitochondrial disease conditions, like coenzyme Q biosynthesis defects. For that reason alternative strategies to correct disturbed energy metabolism have to be developed. New approaches in this direction include nutrition and exercise therapies, alternative gene expression, enzyme-replacement, scavenging of potentially toxic compounds and modulating cell signalling. The effect of some of these interventions has already been explored in humans whilst others are still at the level of single cell research. We review the state of the art of the development of mitochondrial treatment strategies and discuss what steps need to be taken to efficiently approach the huge burden of disease caused by dysfunctional mitochondria.
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Affiliation(s)
- S Koene
- Radboud University Nijmegen Medical Centre, Nijmegen Centre for Mitochondrial Disorders, Nijmegen, The Netherlands
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79
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DiMauro S, Hirano M. Pathogenesis and treatment of mitochondrial disorders. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 652:139-70. [PMID: 20225024 PMCID: PMC10440730 DOI: 10.1007/978-90-481-2813-6_10] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In the past 50 years, our understanding of the biochemical and molecular causes of mitochondrial diseases, defined restrictively as disorders due to defects of the mitochondrial respiratory chain (RC), has made great strides. Mitochondrial diseases can be due to mutations in mitochondrial DNA (mtDNA) or in nuclear DNA (nDNA) and each group can be subdivided into more specific classes. Thus, mtDNA-related disorders can result from mutations in genes affecting protein synthesis in toto or mutations in protein-coding genes. Mendelian mitochondrial disorders can be attributed to mutations in genes that (i) encode subunits of the RC ("direct hits"); (ii) encode assembly proteins or RC complexes ("indirect hits"); (iii) encode factors needed for mtDNA maintenance, replication, or translation (intergenomic signaling); (iv) encode components of the mitochondrial protein import machinery; (v) control the synthesis and composition of mitochondrial membrane phospholipids; and (vi) encode proteins involved in mitochondrial dynamics.In contrast to this wealth of knowledge about etiology, our understanding of pathogenic mechanism is very limited. We discuss pathogenic factors that can influence clinical expression, especially ATP shortage and reactive oxygen radicals (ROS) excess. Therapeutic options are limited and fall into three modalities: (i) symptomatic interventions, which are palliative but crucial for day-to-day management; (ii) radical approaches aimed at correcting the biochemical or molecular error, which are interesting but still largely experimental; and (iii) pharmacological means of interfering with the pathogenic cascade of events (e.g. boosting ATP production or scavenging ROS), which are inconsistently and incompletely effective, but can be safe and helpful.
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Affiliation(s)
- Salvatore DiMauro
- Department of Neurology, Columbia University Medical Center, 3-313 Russ Berrie Medical Science Pavilion, New York, NY 10032, USA.
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80
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Duchêne AM, Pujol C, Maréchal-Drouard L. Import of tRNAs and aminoacyl-tRNA synthetases into mitochondria. Curr Genet 2008; 55:1-18. [PMID: 19083240 DOI: 10.1007/s00294-008-0223-9] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Revised: 11/21/2008] [Accepted: 11/24/2008] [Indexed: 12/13/2022]
Abstract
During evolution, most of the bacterial genes from the ancestral endosymbiotic alpha-proteobacteria at the origin of mitochondria have been either lost or transferred to the nuclear genome. A crucial evolutionary step was the establishment of macromolecule import systems to allow the come back of proteins and RNAs into the organelle. Paradoxically, the few mitochondria-encoded protein genes remain essential and must be translated by a mitochondrial translation machinery mainly constituted by nucleus-encoded components. Two crucial partners of the mitochondrial translation machinery are the aminoacyl-tRNA synthetases and the tRNAs. All mitochondrial aminoacyl-tRNA synthetases and many tRNAs are imported from the cytosol into the mitochondria in eukaryotic cells. During the last few years, their origin and their import into the organelle have been studied in evolutionary distinct organisms and we review here what is known in this field.
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Affiliation(s)
- Anne-Marie Duchêne
- Institut de Biologie Moléculaire des Plantes, Unité Propre de Recherche du CNRS, Associated with Louis Pasteur University, 12 rue du Général Zimmer, 67084, Strasbourg Cedex, France.
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81
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Dimauro S, Rustin P. A critical approach to the therapy of mitochondrial respiratory chain and oxidative phosphorylation diseases. Biochim Biophys Acta Mol Basis Dis 2008; 1792:1159-67. [PMID: 19026744 DOI: 10.1016/j.bbadis.2008.10.015] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2008] [Revised: 10/09/2008] [Accepted: 10/11/2008] [Indexed: 12/17/2022]
Abstract
Taking advantage of a series of questions raised by an association of patients with mitochondrial disease, this review, after a brief overview of basic concepts of mitochondrial bioenergetics and genetics, discusses the pros and cons of a number of practical options in the field of mitochondrial therapy. This makes it clear that, in contrast to the spectacular progress in our understanding of the biochemical and molecular bases of the mitochondrial diseases defined restrictively as disorders due to defects in the mitochondrial respiratory chain, we are still extremely limited in our ability to treat these conditions. We finally discussed the emerging genetic-based strategies that show some promise, even if much work remains to be done.
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Affiliation(s)
- Salvatore Dimauro
- Department of Neurology, Columbia University Medical Center, 313 Russ Berrie Medical Science Pavilion, 1150 St. Nicholas Avenue, New York, NY 10032, USA
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82
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Horvath R, Gorman G, Chinnery PF. How can we treat mitochondrial encephalomyopathies? Approaches to therapy. Neurotherapeutics 2008; 5:558-68. [PMID: 19019307 PMCID: PMC4514691 DOI: 10.1016/j.nurt.2008.07.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Mitochondrial disorders are a heterogeneous group of diseases affecting different organs (brain, muscle, liver, and heart), and the severity of the disease is highly variable. The chronicity and heterogeneity, both clinically and genetically, means that many patients require surveillance follow-up over their lifetime, often involving multiple disciplines. Although our understanding of the genetic defects and their pathological impact underlying mitochondrial diseases has increased over the past decade, this has not been paralleled with regards to treatment. Currently, no definitive pharmacological treatment exists for patients with mitochondrial dysfunction, except for patients with primary deficiency of coenzyme Q10. Pharmacological and nonpharmacological treatments increasingly being investigated include ketogenic diet, exercise, and gene therapy. Management is aimed primarily at minimizing disability, preventing complications, and providing prognostic information and genetic counseling based on current best practice. Here, we evaluate therapies used previously and review current and future treatment modalities for both adults and children with mitochondrial disease.
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Affiliation(s)
- Rita Horvath
- Mitochondrial Research Group, School of Neuroscience, University of Newcastle upon Tyne, UK
| | - Grainne Gorman
- Mitochondrial Research Group, School of Neuroscience, University of Newcastle upon Tyne, UK
| | - Patrick F. Chinnery
- Mitochondrial Research Group, School of Neuroscience, University of Newcastle upon Tyne, UK
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83
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Lee M, Choi JS, Ko KS. Mitochondria targeting delivery of nucleic acids. Expert Opin Drug Deliv 2008; 5:879-87. [DOI: 10.1517/17425247.5.8.879] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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84
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Salinas T, Duchêne AM, Maréchal-Drouard L. Recent advances in tRNA mitochondrial import. Trends Biochem Sci 2008; 33:320-9. [DOI: 10.1016/j.tibs.2008.04.010] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2008] [Revised: 04/22/2008] [Accepted: 04/22/2008] [Indexed: 02/02/2023]
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85
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Mammalian mitochondria have the innate ability to import tRNAs by a mechanism distinct from protein import. Proc Natl Acad Sci U S A 2008; 105:9186-91. [PMID: 18587046 DOI: 10.1073/pnas.0804283105] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mitochondrial genomes generally encode a minimal set of tRNAs necessary for protein synthesis. However, a number of eukaryotes import tRNAs from the cytoplasm into their mitochondria. For instance, Saccharomyces cerevisiae imports cytoplasmic tRNA(Gln) into the mitochondrion without any added protein factors. Here, we examine the existence of a similar active tRNA import system in mammalian mitochondria. We have used subcellular RNA fractions from rat liver and human cells to perform RT-PCR with oligonucleotide primers specific for nucleus-encoded tRNA(CUG)(Gln) and tRNA(UUG)(Gln) species, and we show that these tRNAs are present in rat and human mitochondria in vivo. Import of in vitro transcribed tRNAs, but not of heterologous RNAs, into isolated mitochondria also demonstrates that this process is tRNA-specific and does not require the addition of cytosolic factors. Although this in vitro system requires ATP, it is resistant to inhibitors of the mitochondrial electrochemical gradient, a key component of protein import. tRNA(Gln) import into mammalian mitochondria proceeds by a mechanism distinct from protein import. We also show that both tRNA(Gln) species and a bacterial pre-tRNA(Asp) can be imported in vitro into mitochondria isolated from myoclonic epilepsy with ragged-red fiber cells if provided with sufficient ATP (2 mM). This work suggests that tRNA import is more widespread than previously thought and may be a universal trait of mitochondria. Mutations in mitochondrial tRNA genes have been associated with human disease; the tRNA import system described here could possibly be exploited for the manipulation of defective mitochondria.
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86
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Schapira A. MITOCHONDRIAL DNA AND DISEASE. Continuum (Minneap Minn) 2008. [DOI: 10.1212/01.con.0000275629.24690.30] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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87
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Smirnov A, Tarassov I, Mager-Heckel AM, Letzelter M, Martin RP, Krasheninnikov IA, Entelis N. Two distinct structural elements of 5S rRNA are needed for its import into human mitochondria. RNA (NEW YORK, N.Y.) 2008; 14:749-59. [PMID: 18314502 PMCID: PMC2271358 DOI: 10.1261/rna.952208] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
RNA import into mitochondria is a widespread phenomenon. Studied in details for yeast, protists, and plants, it still awaits thorough investigation for human cells, in which the nuclear DNA-encoded 5S rRNA is imported. Only the general requirements for this pathway have been described, whereas specific protein factors needed for 5S rRNA delivery into mitochondria and its structural determinants of import remain unknown. In this study, a systematic analysis of the possible role of human 5S rRNA structural elements in import was performed. Our experiments in vitro and in vivo show that two distinct regions of the human 5S rRNA molecule are needed for its mitochondrial targeting. One of them is located in the proximal part of the helix I and contains a conserved uncompensated G:U pair. The second and most important one is associated with the loop E-helix IV region with several noncanonical structural features. Destruction or even destabilization of these sites leads to a significant decrease of the 5S rRNA import efficiency. On the contrary, the beta-domain of the 5S rRNA was proven to be dispensable for import, and thus it can be deleted or substituted without affecting the 5S rRNA importability. This finding was used to demonstrate that the 5S rRNA can function as a vector for delivering heterologous RNA sequences into human mitochondria. 5S rRNA-based vectors containing a substitution of a part of the beta-domain by a foreign RNA sequence were shown to be much more efficiently imported in vivo than the wild-type 5S rRNA.
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Affiliation(s)
- Alexandre Smirnov
- Department of Molecular and Cellular Genetics, UMR 7156, Centre National de Recherche Scientifique-Université Louis Pasteur,Strasbourg 67084, France
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88
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Mukherjee S, Mahata B, Mahato B, Adhya S. Targeted mRNA degradation by complex-mediated delivery of antisense RNAs to intracellular human mitochondria. Hum Mol Genet 2008; 17:1292-8. [DOI: 10.1093/hmg/ddn017] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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89
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Ling J, Roy H, Qin D, Rubio MAT, Alfonzo JD, Fredrick K, Ibba M. Pathogenic mechanism of a human mitochondrial tRNAPhe mutation associated with myoclonic epilepsy with ragged red fibers syndrome. Proc Natl Acad Sci U S A 2007; 104:15299-304. [PMID: 17878308 PMCID: PMC2000536 DOI: 10.1073/pnas.0704441104] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2007] [Indexed: 11/18/2022] Open
Abstract
Human mitochondrial tRNA (hmt-tRNA) mutations are associated with a variety of diseases including mitochondrial myopathies, diabetes, encephalopathies, and deafness. Because the current understanding of the precise molecular mechanisms of these mutations is limited, there is no efficient method to treat their associated mitochondrial diseases. Here, we use a variety of known mutations in hmt-tRNA(Phe) to investigate the mechanisms that lead to malfunctions. We tested the impact of hmt-tRNA(Phe) mutations on aminoacylation, structure, and translation elongation-factor binding. The majority of the mutants were pleiotropic, exhibiting defects in aminoacylation, global structure, and elongation-factor binding. One notable exception was the G34A anticodon mutation of hmt-tRNA(Phe) (mitochondrial DNA mutation G611A), which is associated with MERRF (myoclonic epilepsy with ragged red fibers). In vitro, the G34A mutation decreases aminoacylation activity by 100-fold, but does not affect global folding or recognition by elongation factor. Furthermore, G34A hmt-tRNA(Phe) does not undergo adenosine-to-inosine (A-to-I) editing, ruling out miscoding as a possible mechanism for mitochondrial malfunction. To improve the aminoacylation state of the mutant tRNA, we modified the tRNA binding domain of the nucleus-encoded human mitochondrial phenylalanyl-tRNA synthetase, which aminoacylates hmt-tRNA(Phe) with cognate phenylalanine. This variant enzyme displayed significantly improved aminoacylation efficiency for the G34A mutant, suggesting a general strategy to treat certain classes of mitochondrial diseases by modification of the corresponding nuclear gene.
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Affiliation(s)
| | - Hervé Roy
- Department of Microbiology, and
- Ohio State RNA Group, Ohio State University, Columbus, OH 43210
| | | | - Mary Anne T. Rubio
- Department of Microbiology, and
- Ohio State RNA Group, Ohio State University, Columbus, OH 43210
| | - Juan D. Alfonzo
- *Ohio State Biochemistry Program
- Department of Microbiology, and
- Ohio State RNA Group, Ohio State University, Columbus, OH 43210
| | - Kurt Fredrick
- *Ohio State Biochemistry Program
- Department of Microbiology, and
- Ohio State RNA Group, Ohio State University, Columbus, OH 43210
| | - Michael Ibba
- *Ohio State Biochemistry Program
- Department of Microbiology, and
- Ohio State RNA Group, Ohio State University, Columbus, OH 43210
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90
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Affiliation(s)
- Marc Mirande
- Laboratoire d'Enzymologie et Biochimie Structurales, CNRS, Avenue de la Terrasse, 91190 Gif-sur-Yvette, France.
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91
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Mukhopadhyay A, Weiner H. Delivery of drugs and macromolecules to mitochondria. Adv Drug Deliv Rev 2007; 59:729-38. [PMID: 17659805 PMCID: PMC2267434 DOI: 10.1016/j.addr.2007.06.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2007] [Accepted: 06/12/2007] [Indexed: 01/24/2023]
Abstract
Mitochondria is where the bulk of the cell's ATP is produced. Mutations occur to genes coding for members of the complexes involved in energy production. Some are a result of damages to nuclear coded genes and others to mitochondrial coded genes. This review describes approaches to bring small molecules, proteins and RNA/DNA into mitochondria. The purpose is to repair damaged genes as well as to interrupt mitochondrial function including energy production, oxygen radical formation and the apoptotic pathway.
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Affiliation(s)
- Abhijit Mukhopadhyay
- Address correspondence to: Abhijit Mukhopadhyay () or Henry Weiner (), Purdue University, Department of Biochemistry, 175 S. University Street, West Lafayette, Indiana 47907-2063, Phone: (765) 494-1650, Fax: (765) 494-7897
| | - Henry Weiner
- Address correspondence to: Abhijit Mukhopadhyay () or Henry Weiner (), Purdue University, Department of Biochemistry, 175 S. University Street, West Lafayette, Indiana 47907-2063, Phone: (765) 494-1650, Fax: (765) 494-7897
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92
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Abstract
Therapy of mitochondrial encephalomyopathies (defined restrictively as defects of the mitochondrial respiratory chain) is woefully inadequate, despite great progress in our understanding of the molecular bases of these disorders. In this review, we consider sequentially several different therapeutic approaches. Palliative therapy is dictated by good medical practice and includes anticonvulsant medication, control of endocrine dysfunction, and surgical procedures. Removal of noxious metabolites is centered on combating lactic acidosis, but extends to other metabolites. Attempts to bypass blocks in the respiratory chain by administration of electron acceptors have not been successful, but this may be amenable to genetic engineering. Administration of metabolites and cofactors is the mainstay of real-life therapy and is especially important in disorders due to primary deficiencies of specific compounds, such as carnitine or coenzyme Q10. There is increasing interest in the administration of reactive oxygen species scavengers both in primary mitochondrial diseases and in neurodegenerative diseases directly or indirectly related to mitochondrial dysfunction. Aerobic exercise and physical therapy prevent or correct deconditioning and improve exercise tolerance in patients with mitochondrial myopathies due to mitochondrial DNA (mtDNA) mutations. Gene therapy is a challenge because of polyplasmy and heteroplasmy, but interesting experimental approaches are being pursued and include, for example, decreasing the ratio of mutant to wild-type mitochondrial genomes (gene shifting), converting mutated mtDNA genes into normal nuclear DNA genes (allotopic expression), importing cognate genes from other species, or correcting mtDNA mutations with specific restriction endonucleases. Germline therapy raises ethical problems but is being considered for prevention of maternal transmission of mtDNA mutations. Preventive therapy through genetic counseling and prenatal diagnosis is becoming increasingly important for nuclear DNA-related disorders. Progress in each of these approaches provides some glimmer of hope for the future, although much work remains to be done.
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Affiliation(s)
- Salvatore DiMauro
- College of Physicians and Surgeons, Department of Neurology, Columbia University Medical Center, NewYork, NY 10032, USA.
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93
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Gardner JL, Craven L, Turnbull DM, Taylor RW. Experimental Strategies Towards Treating Mitochondrial DNA Disorders. Biosci Rep 2007; 27:139-50. [PMID: 17492502 DOI: 10.1007/s10540-007-9042-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
An extensive range of molecular defects have been identified in the human mitochondrial genome (mtDNA), causing a range of clinical phenotypes characterized by mitochondrial respiratory chain dysfunction. Sadly, given the complexities of mitochondrial genetics, there are no available cures for mtDNA disorders. In this review, we consider experimental, genetic-based strategies that have been or are being explored towards developing treatments, focussing on two specific areas which we are actively pursuing—assessing the benefit of exercise training for patients with mtDNA defects, and the prevention of mtDNA disease transmission.
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Affiliation(s)
- Julie L Gardner
- Mitochondrial Research Group, School of Neurology, Neurobiology and Psychiatry, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
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94
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Kamenski P, Kolesnikova O, Jubenot V, Entelis N, Krasheninnikov IA, Martin RP, Tarassov I. Evidence for an Adaptation Mechanism of Mitochondrial Translation via tRNA Import from the Cytosol. Mol Cell 2007; 26:625-37. [PMID: 17560369 DOI: 10.1016/j.molcel.2007.04.019] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2007] [Revised: 04/01/2007] [Accepted: 04/24/2007] [Indexed: 11/30/2022]
Abstract
Although mitochondrial import of nuclear DNA-encoded RNAs is widely occurring, their functions in the organelles are not always understood. Mitochondrial function(s) of tRNA(Lys)(CUU), tRK1, targeted into Saccharomyces cerevisiae mitochondria was mysterious, since mitochondrial DNA-encoded tRNA(Lys)(UUU), tRK3, was hypothesized to decode both lysine codons, AAA and AAG. Mitochondrial targeting of tRK1 depends on the precursor of mitochondrial lysyl-tRNA synthetase, pre-Msk1p. Here we show that substitution of pre-Msk1p by its Ashbya gossypii ortholog results in a strain in which tRK3 is aminoacylated, while tRK1 is not imported. At elevated temperature, drop of tRK1 import inhibits mitochondrial translation of mRNAs containing AAG codons, which coincides with the impaired 2-thiolation of tRK3 anticodon wobble nucleotide. Restoration of tRK1 import cures the translational defect, suggesting the role of tRK1 in conditional adaptation of mitochondrial protein synthesis. In contrast with the known ways of organellar translation control, this mechanism exploits the RNA import pathway.
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MESH Headings
- Amino Acid Sequence
- Base Sequence
- Biological Transport, Active
- Cytosol/metabolism
- DNA, Fungal/genetics
- DNA, Mitochondrial/genetics
- Lysine-tRNA Ligase/chemistry
- Lysine-tRNA Ligase/metabolism
- Mitochondria/metabolism
- Models, Biological
- Molecular Sequence Data
- Nucleic Acid Conformation
- Protein Biosynthesis
- RNA, Fungal/chemistry
- RNA, Fungal/genetics
- RNA, Fungal/metabolism
- RNA, Transfer/genetics
- RNA, Transfer/metabolism
- RNA, Transfer, Lys/chemistry
- RNA, Transfer, Lys/genetics
- RNA, Transfer, Lys/metabolism
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/metabolism
- Saccharomycetales/genetics
- Saccharomycetales/metabolism
- Sequence Homology, Amino Acid
- Species Specificity
- Temperature
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Affiliation(s)
- Piotr Kamenski
- UMR 7156, CNRS, Université Louis Pasteur, Department of Molecular and Cellular Genetics, 21 rue René Descartes, 67084 Strasbourg, France
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95
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Rustin P, T Jacobs H, Dietrich A, N Lightowlers R, Tarassov I, Corral-Debrinski M. Adresser du matériel allogène dans le compartiment mitochondrial. Med Sci (Paris) 2007; 23:519-25. [PMID: 17502069 DOI: 10.1051/medsci/2007235519] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Mitochondrial disorders can not be ignored anymore in most medical areas. They include specific and widespread organ involvement, with tissue degeneration or tumor formation, being the target of numerous viruses, e.g. the HIV. Primary or secondary actors, mitochondrial dysfunctions are also supposedly playing a role in the ageing process. Despite the progresses made in the identification of their molecular bases, nearly all remains to be done as regards therapy. Research dealing with mitochondrial physiology and pathology has a long history in France and is thus not a surprise if four French teams, coming from these fundamental domains, are involved in the challenge to find ways to fight these diseases. The directions described are working tracks which promise to be long and full of pitfalls. Being original, they share a part of risk and uncertainty, but they are also with great potential with high stakes if considering the impact of these diseases.
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Affiliation(s)
- Pierre Rustin
- Inserm U676, Hôpital Robert Debré et Université Paris 7, Faculté de Médecine Denis Diderot, Paris, France.
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96
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Kamenski PA, Vinogradova EN, Krasheninnikov IA, Tarassov IA. Directed import of macromolecules into mitochondria. Mol Biol 2007. [DOI: 10.1134/s0026893307020021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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97
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Lohia A. Leishmanial proteins can correct human mitochondrial mutations. J Biosci 2007; 31:507-8. [PMID: 17301486 DOI: 10.1007/bf02708400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Anuradha Lohia
- Department of Biochemistry, Bose Institute, Kolkata 700 054, India.
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98
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Mager-Heckel AM, Entelis N, Brandina I, Kamenski P, Krasheninnikov IA, Martin RP, Tarassov I. The analysis of tRNA import into mammalian mitochondria. Methods Mol Biol 2007; 372:235-253. [PMID: 18314730 DOI: 10.1007/978-1-59745-365-3_17] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Ribonucleic acid (RNA) import into mitochondria occurs in a variety of organisms. In mammalian cells, several small RNAs are imported in a natural manner; transfer RNAs (tRNAs) can be imported in an artificial way, following expression of corresponding genes from another organism (yeast) in the nucleus. We describe how to establish and to analyze such import mechanisms in cultured human cells. In detail, we describe (1) the construction of plasmids expressing importable yeast tRNA derivatives in human cells, (2) the procedure of transfection of either immortalized cybrid cell lines or primary patient's fibroblasts and downregulation of tRNA expression directed by small interfering RNA (siRNA) as a way to demonstrate the effect of import in vivo, (3) the methods of mitochondrial RNA isolation from the transfectants, and (4) approaches for quantification of RNA mitochondrial import.
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99
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D'Souza GGM, Boddapati SV, Weissig V. Gene therapy of the other genome: the challenges of treating mitochondrial DNA defects. Pharm Res 2006; 24:228-38. [PMID: 17180727 DOI: 10.1007/s11095-006-9150-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2006] [Accepted: 08/17/2006] [Indexed: 01/08/2023]
Abstract
Human mitochondrial DNA is a 16.5 kb circular DNA molecule located inside the mitochondrial matrix. Although accounting for only about 1% of total cellular DNA, defects in mitochondrial DNA have been found to have major effects on human health. A single mtDNA mutation may cause a bewildering variety of clinical symptoms mainly involving the neuromuscular system at any age of onset. Despite significant advances in the understanding of mitochondrial DNA defects at a molecular level, the clinical diagnosis of mtDNA diseases remains a significant challenge and effective therapies for such diseases are as yet unavailable. In contrast to gene therapy for chromosomal DNA defects, mitochondrial gene therapy is a field that is still in its infancy and attempts towards gene therapy of the mitochondrial genome are rare. In this review we outline what we believe are the unique challenges associated with the correction of mtDNA mutations and summarize current approaches to gene therapy for the "other genome".
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Affiliation(s)
- Gerard G M D'Souza
- Bouvé College of Health Sciences, Department of Pharmaceutical Sciences, Northeastern University, 360 Huntington Avenue, 211 Mugar Building, Boston, Massachusetts 02115, USA
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100
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Mahata B, Mukherjee S, Mishra S, Bandyopadhyay A, Adhya S. Functional Delivery of a Cytosolic tRNA into Mutant Mitochondria of Human Cells. Science 2006; 314:471-4. [PMID: 17053148 DOI: 10.1126/science.1129754] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Many maternally inherited and incurable neuromyopathies are caused by mutations in mitochondrial (mt) transfer RNA (tRNA) genes. Kinetoplastid protozoa, including Leishmania, have evolved specialized systems for importing nucleus-encoded tRNAs into mitochondria. We found that the Leishmania RNA import complex (RIC) could enter human cells by a caveolin-1-dependent pathway, where it induced import of endogenous cytosolic tRNAs, including tRNA(Lys), and restored mitochondrial function in a cybrid harboring a mutant mt tRNA(Lys) (MT-TK) gene. The use of protein complexes to modulate mitochondrial function may help in the management of such genetic disorders.
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Affiliation(s)
- Bidesh Mahata
- Genetic Engineering, Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Calcutta 700032, India
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