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Wang S, Kang Y, Wang R, Deng J, Yu Y, Yu J, Wang J. Emerging Roles of NDUFS8 Located in Mitochondrial Complex I in Different Diseases. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27248754. [PMID: 36557887 PMCID: PMC9783039 DOI: 10.3390/molecules27248754] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 12/05/2022] [Accepted: 12/06/2022] [Indexed: 12/14/2022]
Abstract
NADH:ubiquinone oxidoreductase core subunit S8 (NDUFS8) is an essential core subunit and component of the iron-sulfur (FeS) fragment of mitochondrial complex I directly involved in the electron transfer process and energy metabolism. Pathogenic variants of the NDUFS8 are relevant to infantile-onset and severe diseases, including Leigh syndrome, cancer, and diabetes mellitus. With over 1000 nuclear genes potentially causing a mitochondrial disorder, the current diagnostic approach requires targeted molecular analysis, guided by a combination of clinical and biochemical features. Currently, there are only several studies on pathogenic variants of the NDUFS8 in Leigh syndrome, and a lack of literature on its precise mechanism in cancer and diabetes mellitus exists. Therefore, NDUFS8-related diseases should be extensively explored and precisely diagnosed at the molecular level with the application of next-generation sequencing technologies. A more distinct comprehension will be needed to shed light on NDUFS8 and its related diseases for further research. In this review, a comprehensive summary of the current knowledge about NDUFS8 structural function, its pathogenic mutations in Leigh syndrome, as well as its underlying roles in cancer and diabetes mellitus is provided, offering potential pathogenesis, progress, and therapeutic target of different diseases. We also put forward some problems and solutions for the following investigations.
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Affiliation(s)
- Sifan Wang
- Department of Pathology, Xiangya Hospital, Central South University, Changsha 410008, China; (S.W.); (Y.K.); (R.W.); (J.D.); (Y.Y.)
- Department of Pathology, School of Basic Medicine, Central South University, Changsha 410008, China
- Xiangya School of Medicine, Central South University, Changsha 410013, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha 410008, China
- Department of Dermatology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China
| | - Yuanbo Kang
- Department of Pathology, Xiangya Hospital, Central South University, Changsha 410008, China; (S.W.); (Y.K.); (R.W.); (J.D.); (Y.Y.)
- Department of Pathology, School of Basic Medicine, Central South University, Changsha 410008, China
- Xiangya School of Medicine, Central South University, Changsha 410013, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha 410008, China
- Department of Dermatology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China
| | - Ruifeng Wang
- Department of Pathology, Xiangya Hospital, Central South University, Changsha 410008, China; (S.W.); (Y.K.); (R.W.); (J.D.); (Y.Y.)
- Department of Pathology, School of Basic Medicine, Central South University, Changsha 410008, China
| | - Junqi Deng
- Department of Pathology, Xiangya Hospital, Central South University, Changsha 410008, China; (S.W.); (Y.K.); (R.W.); (J.D.); (Y.Y.)
- Department of Pathology, School of Basic Medicine, Central South University, Changsha 410008, China
| | - Yupei Yu
- Department of Pathology, Xiangya Hospital, Central South University, Changsha 410008, China; (S.W.); (Y.K.); (R.W.); (J.D.); (Y.Y.)
- Department of Pathology, School of Basic Medicine, Central South University, Changsha 410008, China
| | - Jun Yu
- Department of Neurology, Third Xiangya Hospital, Central South University, Changsha 410008, China
- Correspondence: (J.Y.); (J.W.); Tel./Fax: +86-731-84805411 (J.W.)
| | - Junpu Wang
- Department of Pathology, Xiangya Hospital, Central South University, Changsha 410008, China; (S.W.); (Y.K.); (R.W.); (J.D.); (Y.Y.)
- Department of Pathology, School of Basic Medicine, Central South University, Changsha 410008, China
- Xiangya School of Medicine, Central South University, Changsha 410013, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha 410008, China
- Correspondence: (J.Y.); (J.W.); Tel./Fax: +86-731-84805411 (J.W.)
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Kishita Y, Shimura M, Kohda M, Fushimi T, Nitta KR, Yatsuka Y, Hirose S, Ideguchi H, Ohtake A, Murayama K, Okazaki Y. Genome sequencing and RNA-seq analyses of mitochondrial complex I deficiency revealed Alu insertion-mediated deletion in NDUFV2. Hum Mutat 2021; 42:1422-1428. [PMID: 34405929 DOI: 10.1002/humu.24274] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 06/25/2021] [Accepted: 07/15/2021] [Indexed: 11/08/2022]
Abstract
Isolated complex I deficiency is the most common cause of pediatric mitochondrial disease. Exome sequencing (ES) has revealed many complex I causative genes. However, there are limitations associated with identifying causative genes by ES analysis. In this study, we performed multiomics analysis to reveal the causal variants. We here report two cases with mitochondrial complex I deficiency. In both cases, ES identified a novel c.580G>A (p.Glu194Lys) variant in NDUFV2. One case additionally harbored c.427C>T (p.Arg143*), but no other variants were observed in the other case. RNA sequencing showed aberrant exon splicing of NDUFV2 in the unsolved case. Genome sequencing revealed a novel heterozygous deletion in NDUFV2, which included one exon and resulted in exon skipping. Detailed examination of the breakpoint revealed that an Alu insertion-mediated rearrangement caused the deletion. Our report reveals that combined use of transcriptome sequencing and GS was effective for diagnosing cases that were unresolved by ES.
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Affiliation(s)
- Yoshihito Kishita
- Diagnostics and Therapeutics of Intractable Diseases, Intractable Disease Research Center, Graduate School of Medicine, Juntendo University, Tokyo, Japan.,Department of Life Science, Faculty of Science and Engineering, Kindai University, Osaka, Japan
| | - Masaru Shimura
- Department of Metabolism, Chiba Children's Hospital, Chiba, Japan
| | - Masakazu Kohda
- Diagnostics and Therapeutics of Intractable Diseases, Intractable Disease Research Center, Graduate School of Medicine, Juntendo University, Tokyo, Japan
| | - Takuya Fushimi
- Department of Metabolism, Chiba Children's Hospital, Chiba, Japan
| | - Kazuhiro R Nitta
- Diagnostics and Therapeutics of Intractable Diseases, Intractable Disease Research Center, Graduate School of Medicine, Juntendo University, Tokyo, Japan
| | - Yukiko Yatsuka
- Diagnostics and Therapeutics of Intractable Diseases, Intractable Disease Research Center, Graduate School of Medicine, Juntendo University, Tokyo, Japan
| | - Shinichi Hirose
- General Medical Research Center, School of Medicine, Fukuoka University, Fukuoka, Japan
| | - Hiroshi Ideguchi
- Department of Pediatrics, Fukuoka Sanno Hospital, Fukuoka, Japan
| | - Akira Ohtake
- Department of Pediatrics & Clinical Genomics, Faculty of Medicine, Saitama Medical University, Saitama, Japan.,Center for Intractable Diseases, Saitama Medical University Hospital, Saitama, Japan
| | - Kei Murayama
- Diagnostics and Therapeutics of Intractable Diseases, Intractable Disease Research Center, Graduate School of Medicine, Juntendo University, Tokyo, Japan.,Department of Metabolism, Chiba Children's Hospital, Chiba, Japan.,Center for Medical Genetics, Chiba Children's Hospital, Chiba, Japan
| | - Yasushi Okazaki
- Diagnostics and Therapeutics of Intractable Diseases, Intractable Disease Research Center, Graduate School of Medicine, Juntendo University, Tokyo, Japan.,Laboratory for Comprehensive Genomic Analysis, RIKEN Centre for Integrative Medical Sciences, Kanagawa, Japan
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TAT-Conjugated NDUFS8 Can Be Transduced into Mitochondria in a Membrane-Potential-Independent Manner and Rescue Complex I Deficiency. Int J Mol Sci 2021; 22:ijms22126524. [PMID: 34204592 PMCID: PMC8234171 DOI: 10.3390/ijms22126524] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 06/12/2021] [Accepted: 06/15/2021] [Indexed: 12/21/2022] Open
Abstract
NADH dehydrogenase (ubiquinone) Fe-S protein 8 (NDUFS8) is a nuclear-encoded core subunit of human mitochondrial complex I. Defects in NDUFS8 are associated with Leigh syndrome and encephalomyopathy. Cell-penetrating peptide derived from the HIV-1 transactivator of transcription protein (TAT) has been successfully applied as a carrier to bring fusion proteins into cells without compromising the biological function of the cargoes. In this study, we developed a TAT-mediated protein transduction system to rescue complex I deficiency caused by NDUFS8 defects. Two fusion proteins (TAT-NDUFS8 and NDUFS8-TAT) were exogenously expressed and purified from Escherichia coli for transduction of human cells. In addition, similar constructs were generated and used in transfection studies for comparison. The results showed that both exogenous TAT-NDUFS8 and NDUFS8-TAT were delivered into mitochondria and correctly processed. Interestingly, the mitochondrial import of TAT-containing NDUFS8 was independent of mitochondrial membrane potential. Treatment with TAT-NDUFS8 not only significantly improved the assembly of complex I in an NDUFS8-deficient cell line, but also partially rescued complex I functions both in the in-gel activity assay and the oxygen consumption assay. Our current findings suggest the considerable potential of applying the TAT-mediated protein transduction system for treatment of complex I deficiency.
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Ortigoza-Escobar JD, Oyarzabal A, Montero R, Artuch R, Jou C, Jiménez C, Gort L, Briones P, Muchart J, López-Gallardo E, Emperador S, Pesini ER, Montoya J, Pérez B, Rodríguez-Pombo P, Pérez-Dueñas B. Ndufs4 related Leigh syndrome: A case report and review of the literature. Mitochondrion 2016; 28:73-8. [DOI: 10.1016/j.mito.2016.04.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 03/31/2016] [Accepted: 04/01/2016] [Indexed: 12/30/2022]
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Widgren P, Hurme A, Falck A, Keski-Filppula R, Remes AM, Moilanen J, Majamaa K, Kervinen M, Uusimaa J. Genetic aetiology of ophthalmological manifestations in children - a focus on mitochondrial disease-related symptoms. Acta Ophthalmol 2016; 94:83-91. [PMID: 26448634 DOI: 10.1111/aos.12897] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Accepted: 08/23/2015] [Indexed: 11/29/2022]
Abstract
PURPOSE To investigate the association of mutations in the mitochondrial DNA (mtDNA) or nuclear candidate genes with mitochondrial disease-related ophthalmic manifestations (nystagmus, ptosis, ophthalmoplegia, optic neuropathy and retinopathy) in children. METHODS A retrospective cohort of children (n = 98) was identified from the medical record files of a tertiary care hospital. The entire mtDNA and nuclear genes POLG1, OPA1 and PEO1 were analysed from the available DNA samples (n = 38). Furthermore, some nuclear candidate genes were investigated based on family history and phenotype. Rare mtDNA mutations were evaluated using in silico predictors and sequence alignment. RESULTS Three patients had previously identified mutations in mtDNA that are associated with optic neuropathy (in MT-ND6 and MT-ND1) and nystagmus (in tRNA Arg). Nine rare mutations in MT-ATP6 were identified in seven patients, of whom four manifested with retinopathy and three had clusters of MT-ATP6 mutations. Nuclear PEO1 and OPA1 were unchanged in all samples, but a patient with nystagmus had a heterozygous POLG1 mutation. The analysis of nuclear candidate genes revealed mutations in NDUF8 (patient with nystagmus), TULP1 (patient with optic neuropathy, nystagmus and retinopathy) and RP2 (patient with retinopathy) genes. CONCLUSIONS Children with retinopathy, nystagmus or optic neuropathy, especially together with developmental delay or positive family history, should be considered for mitochondrial disease. MT-ATP6 should be taken into account for children with retinopathy of unknown aetiology.
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Affiliation(s)
- Paula Widgren
- PEDEGO Research Unit; University of Oulu; Oulu Finland
- Department of Children and Adolescents; Division of Pediatric Neurology; Oulu University Hospital; Oulu Finland
- Department of Ophthalmology; Oulu University Hospital; Oulu Finland
- Medical Research Center Oulu; University of Oulu; Oulu Finland
| | - Anri Hurme
- PEDEGO Research Unit; University of Oulu; Oulu Finland
- Department of Children and Adolescents; Division of Pediatric Neurology; Oulu University Hospital; Oulu Finland
- Medical Research Center Oulu; University of Oulu; Oulu Finland
| | - Aura Falck
- Department of Ophthalmology; Oulu University Hospital; Oulu Finland
- Medical Research Center Oulu; University of Oulu; Oulu Finland
| | - Riikka Keski-Filppula
- PEDEGO Research Unit; University of Oulu; Oulu Finland
- Medical Research Center Oulu; University of Oulu; Oulu Finland
- Department of Clinical Genetics; Oulu University Hospital; Oulu Finland
| | - Anne M Remes
- Institute of Clinical Medicine - Neurology; University of Eastern Finland; Kuopio Finland
- Department of Neurology; Kuopio University Hospital; Kuopio Finland
| | - Jukka Moilanen
- PEDEGO Research Unit; University of Oulu; Oulu Finland
- Medical Research Center Oulu; University of Oulu; Oulu Finland
- Department of Clinical Genetics; Oulu University Hospital; Oulu Finland
| | - Kari Majamaa
- Medical Research Center Oulu; University of Oulu; Oulu Finland
- Research Unit of Clinical Neuroscience and Medical Research Center Oulu; University of Oulu; Oulu Finland
- Department of Neurology; Oulu University Hospital; Oulu Finland
| | - Marko Kervinen
- Department of Ophthalmology; Oulu University Hospital; Oulu Finland
- Medical Research Center Oulu; University of Oulu; Oulu Finland
| | - Johanna Uusimaa
- PEDEGO Research Unit; University of Oulu; Oulu Finland
- Department of Children and Adolescents; Division of Pediatric Neurology; Oulu University Hospital; Oulu Finland
- Medical Research Center Oulu; University of Oulu; Oulu Finland
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Cameron JM, MacKay N, Feigenbaum A, Tarnopolsky M, Blaser S, Robinson BH, Schulze A. Exome sequencing identifies complex I NDUFV2 mutations as a novel cause of Leigh syndrome. Eur J Paediatr Neurol 2015; 19:525-32. [PMID: 26008862 DOI: 10.1016/j.ejpn.2015.05.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Revised: 02/12/2015] [Accepted: 05/05/2015] [Indexed: 12/30/2022]
Abstract
BACKGROUND Two siblings with hypertrophic cardiomyopathy and brain atrophy were diagnosed with Complex I deficiency based on low enzyme activity in muscle and high lactate/pyruvate ratio in fibroblasts. METHODS Whole exome sequencing results of fibroblast gDNA from one sibling was narrowed down to 190 SNPs or In/Dels in 185 candidate genes by selecting non-synonymous coding sequence base pair changes that were not present in the SNP database. RESULTS Two compound heterozygous mutations were identified in both siblings in NDUFV2, encoding the 24 kDa subunit of Complex I. The intronic mutation (c.IVS2 + 1delGTAA) is disease causing and has been reported before. The other mutation is novel (c.669_670insG, p.Ser224Valfs*3) and predicted to cause a pathogenic frameshift in the protein. Subsequent investigation of 10 probands with complex I deficiency from different families revealed homozygosity for the intronic c.IVS2 + 1delGTAA mutation in a second, consanguineous family. In this family three of five siblings were affected. Interestingly, they presented with Leigh syndrome but no cardiac involvement. The same genotype had been reported previously in a two families but presenting with hypertrophic cardiomyopathy, trunk hypotonia and encephalopathy. CONCLUSION We have identified NDUFV2 mutations in two families with Complex I deficiency, including a novel mutation. The diagnosis of Leigh syndrome expands the clinical phenotypes associated with the c.IVS2 + 1delGTAA mutation in this gene.
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Affiliation(s)
- Jessie M Cameron
- Genetics & Genome Biology Program, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON M5G 0A4, Canada.
| | - Nevena MacKay
- Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada
| | - Annette Feigenbaum
- Division of Clinical and Metabolic Genetics, The Hospital for Sick Children and University of Toronto, Toronto, ON M5G 1X8, Canada.
| | - Mark Tarnopolsky
- Department of Pediatrics, McMaster University Medical Center, Hamilton, ON L8N 3Z5, Canada.
| | - Susan Blaser
- Department of Radiology, The Hospital for Sick Children and University of Toronto, ON M5G 1X8, Canada.
| | - Brian H Robinson
- Genetics & Genome Biology Program, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada.
| | - Andreas Schulze
- Genetics & Genome Biology Program, Peter Gilgan Centre for Research and Learning, 686 Bay Street, Toronto, ON M5G 0A4, Canada; Division of Clinical and Metabolic Genetics, The Hospital for Sick Children and University of Toronto, Toronto, ON M5G 1X8, Canada.
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Iommarini L, Calvaruso MA, Kurelac I, Gasparre G, Porcelli AM. Complex I impairment in mitochondrial diseases and cancer: Parallel roads leading to different outcomes. Int J Biochem Cell Biol 2013; 45:47-63. [DOI: 10.1016/j.biocel.2012.05.016] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 05/03/2012] [Accepted: 05/24/2012] [Indexed: 02/06/2023]
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Pagniez-Mammeri H, Loublier S, Legrand A, Bénit P, Rustin P, Slama A. Mitochondrial complex I deficiency of nuclear origin I. Structural genes. Mol Genet Metab 2012; 105:163-72. [PMID: 22142868 DOI: 10.1016/j.ymgme.2011.11.188] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2011] [Revised: 11/09/2011] [Accepted: 11/09/2011] [Indexed: 10/15/2022]
Abstract
Complex I (or NADH-ubiquinone oxidoreductase), is by far the largest respiratory chain complex with 38 subunits nuclearly encoded and 7 subunits encoded by the mitochondrial genome. Its deficiency is the most frequently encountered in mitochondrial disorders. Here, we summarize recent data obtained on architecture of complex I, and review the pathogenic mutations identified to date in nuclear structural complex I genes. The structural NDUFS1, NDUFS2, NDUFV1, and NDUFS4 genes are mutational hot spot genes for isolated complex I deficiency. The majority of the pathogenic mutations are private and the genotype-phenotype correlation is inconsistent in the rare recurrent mutations.
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Affiliation(s)
- Hélène Pagniez-Mammeri
- Laboratoire de Biochimie, APHP Hôpital de Bicêtre, 78 rue du Général Leclerc, 94275 Le Kremlin Bicêtre cedex, France
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Tuppen HAL, Hogan VE, He L, Blakely EL, Worgan L, Al-Dosary M, Saretzki G, Alston CL, Morris AA, Clarke M, Jones S, Devlin AM, Mansour S, Chrzanowska-Lightowlers ZMA, Thorburn DR, McFarland R, Taylor RW. The p.M292T NDUFS2 mutation causes complex I-deficient Leigh syndrome in multiple families. ACTA ACUST UNITED AC 2010; 133:2952-63. [PMID: 20819849 PMCID: PMC2947428 DOI: 10.1093/brain/awq232] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Isolated complex I deficiency is the most frequently observed oxidative phosphorylation defect in children with mitochondrial disease, leading to a diverse range of clinical presentations, including Leigh syndrome. For most patients the genetic cause of the biochemical defect remains unknown due to incomplete understanding of the complex I assembly process. Nonetheless, a plethora of pathogenic mutations have been described to date in the seven mitochondrial-encoded subunits of complex I as well as in 12 of the nuclear-encoded subunits and in six assembly factors. Whilst several mitochondrial DNA mutations are recurrent, the majority of these mutations are reported in single families. We have sequenced core structural and functional nuclear-encoded subunits of complex I in a cohort of 34 paediatric patients with isolated complex I deficiency, identifying pathogenic mutations in 6 patients. These included a novel homozygous NDUFS1 mutation in an Asian child with Leigh syndrome, a previously identified NDUFS8 mutation (c.236C>T, p.P79L) in a second Asian child with Leigh-like syndrome and six novel, compound heterozygous NDUFS2 mutations in four white Caucasian patients with Leigh or Leigh-like syndrome. Three of these children harboured an identical NDUFS2 mutation (c.875T>C, p.M292T), which was also identified in conjunction with a novel NDUFS2 splice site mutation (c.866+4A>G) in a fourth Caucasian child who presented to a different diagnostic centre, with microsatellite and single nucleotide polymorphism analyses indicating that this was due to an ancient common founder event. Our results confirm that NDUFS2 is a mutational hotspot in Caucasian children with isolated complex I deficiency and recommend the routine diagnostic investigation of this gene in patients with Leigh or Leigh-like phenotypes.
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Affiliation(s)
- Helen A L Tuppen
- Mitochondrial Research Group, Institute for Ageing and Health, Newcastle University, Medical School, Framlington Place, Newcastle upon Tyne, UK
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Ugalde C, Morán M, Blázquez A, Arenas J, Martín MA. Mitochondrial Disorders Due to Nuclear OXPHOS Gene Defects. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 652:85-116. [DOI: 10.1007/978-90-481-2813-6_7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Feng D, Witkowski A, Smith S. Down-regulation of mitochondrial acyl carrier protein in mammalian cells compromises protein lipoylation and respiratory complex I and results in cell death. J Biol Chem 2009; 284:11436-45. [PMID: 19221180 DOI: 10.1074/jbc.m806991200] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The objective of this study was to evaluate the physiological importance of the mitochondrial fatty acid synthesis pathway in mammalian cells using the RNA interference strategy. Transfection of HEK293T cells with small interfering RNAs targeting the acyl carrier protein (ACP) component reduced ACP mRNA and protein levels by >85% within 24 h. The earliest phenotypic changes observed were a marked decrease in the proportion of post-translationally lipoylated mitochondrial proteins recognized by anti-lipoate antibodies and a reduction in their catalytic activity, and a slowing of the cell growth rate. Later effects observed included a reduction in the specific activity of respiratory complex I, lowered mitochondrial membrane potential, the development of cytoplasmic membrane blebs containing high levels of reactive oxygen species and ultimately, cell death. Supplementation of the culture medium with lipoic acid offered some protection against oxidative damage but did not reverse the protein lipoylation defect. These observations are consistent with a dual role for ACP in mammalian mitochondrial function. First, as a key component of the mitochondrial fatty acid biosynthetic pathway, ACP plays an essential role in providing the octanoyl-ACP precursor required for the protein lipoylation pathway. Second, as one of the subunits of complex I, ACP is required for the efficient functioning of the electron transport chain and maintenance of normal mitochondrial membrane potential.
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Affiliation(s)
- Dejiang Feng
- Children's Hospital Oakland Research Institute, Oakland, California 94609, USA
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Uusimaa J, Hinttala R, Rantala H, Päivärinta M, Herva R, Röyttä M, Soini H, Moilanen JS, Remes AM, Hassinen IE, Majamaa K. Homozygous W748S mutation in the POLG1 gene in patients with juvenile-onset Alpers syndrome and status epilepticus. Epilepsia 2008; 49:1038-45. [PMID: 18294203 DOI: 10.1111/j.1528-1167.2008.01544.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
PURPOSE Polymerase gamma (POLG) is the sole enzyme in the replication of mitochondrial DNA (mtDNA). Numerous mutations in the POLG1 gene have been detected recently in patients with various phenotypes including a classic infantile-onset Alpers-Huttenlocher syndrome (AHS). Here we studied the molecular etiology of juvenile-onset AHS manifesting with status epilepticus and liver disease in three teenagers. PATIENTS AND METHODS We examined 14- and 17-year-old female siblings (patients 1 and 2) and an unrelated 15-year-old girl (patient 3) with juvenile-onset AHS, sequenced POLG1, and the entire mtDNA, examined mtDNA deletions by amplification of the full-length mtDNA with the long PCR method and used real-time PCR to quantify mtDNA in the tissue samples. RESULTS The initial manifestations were migraine-like headache and epilepsy, and the terminal manifestations status epilepticus and hepatic failure. A homozygous W748S mutation in POLG1 was detected in the three patients. No deletions or pathogenic point mutations were found in mtDNA, but all three patients had mtDNA depletion. CONCLUSIONS POLG mutations should be considered in cases of teenagers and young adults with a sudden onset of intractable seizures or status epilepticus, and acute liver failure. The W748S POLG1 mutation seems to lead to tissue-specific, partial mtDNA depletion in patients with juvenile-onset Alpers syndrome. Valproic acid should be avoided in the treatment of epileptic seizures in these patients.
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Fernandez-Moreira D, Ugalde C, Smeets R, Rodenburg RJT, Lopez-Laso E, Ruiz-Falco ML, Briones P, Martin MA, Smeitink JAM, Arenas J. X-linked NDUFA1 gene mutations associated with mitochondrial encephalomyopathy. Ann Neurol 2007; 61:73-83. [PMID: 17262856 DOI: 10.1002/ana.21036] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
OBJECTIVE Mitochondrial complex I deficiency is the commonest diagnosed respiratory chain defect, being genetically heterogeneous. The male preponderance of previous patient cohorts suggested an X-linked underlying genetic defect. We investigated mutations in the X-chromosomal complex I structural genes, NDUFA1 and NDUFB11, as a novel cause of mitochondrial encephalomyopathy. METHODS We sequenced 12 nuclear genes and the mitochondrial DNA-encoded complex I genes in 26 patients with respiratory chain complex I defect. Novel mutations were confirmed by polymerase chain reaction restriction length polymorphism. Assembly/stability studies in fibroblasts were performed using two-dimensional blue native gel electrophoresis. RESULTS Two novel p.Gly8Arg and p.Arg37Ser hemizygous mutations in NDUFA1 were identified in two unrelated male patients presenting with Leigh's syndrome and with myoclonic epilepsy and developmental delay, respectively. Two-dimensional blue native gel electrophoresis showed decreased levels of intact complex I with no accumulation of lower molecular weight subcomplexes, indicating that assembly, stability, or both are compromised. INTERPRETATION Mutations in the X-linked NDUFA1 gene result in complex I defect and encephalomyopathy. Assembly/stability analysis might give an explanation for the different clinical phenotypes and become useful for future diagnostic purposes.
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Early-onset ophthalmoplegia in Leigh-like syndrome due to NDUFV1 mutations. Pediatr Neurol 2007; 36:54-7. [PMID: 17162199 DOI: 10.1016/j.pediatrneurol.2006.08.007] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2006] [Revised: 06/09/2006] [Accepted: 08/09/2006] [Indexed: 10/23/2022]
Abstract
Mitochondrial disorders can be linked to mutations in both mitochondrial and nuclear deoxyribonucleic acid, corresponding to various clinical phenotypes. Mutations in nuclear genes, including NDUFV1, have been associated with severe encephalomyopathies in infants, but genotype-phenotype correlations have remained elusive. This report details the complete clinical, biochemical, and molecular data of a 7-year-old male who presented at the age of 7 months with progressive ophthalmoplegia and later developed cerebellar ataxia, spasticity, and dystonia. Complex I deficiency was demonstrated in muscle, and two pathogenic missense mutations were present in the NDUFV1 gene. Ketogenic diet has seemingly improved the oculomotor palsy but has been unable to correct other neurologic symptoms. Considering other cases from the literature, this report broadens our understanding of genotype-phenotype correlations for NDUFV1 mutations and illustrates a potential and partial efficacy of ketogenic diet in complex I deficient patients.
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Luft FC. How complex is Complex I? J Mol Med (Berl) 2005; 83:749-51. [PMID: 16143865 DOI: 10.1007/s00109-005-0708-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Friedrich C Luft
- Franz Volhard Clinic, HELIOS Kliniken Berlin, Medical Faculty of the Charite, Humboldt University, Germany.
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