1
|
Meshrkey F, Scheulin KM, Littlejohn CM, Stabach J, Saikia B, Thorat V, Huang Y, LaFramboise T, Lesnefsky EJ, Rao RR, West FD, Iyer S. Induced pluripotent stem cells derived from patients carrying mitochondrial mutations exhibit altered bioenergetics and aberrant differentiation potential. Stem Cell Res Ther 2023; 14:320. [PMID: 37936209 PMCID: PMC10631039 DOI: 10.1186/s13287-023-03546-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 10/25/2023] [Indexed: 11/09/2023] Open
Abstract
BACKGROUND Human mitochondrial DNA mutations are associated with common to rare mitochondrial disorders, which are multisystemic with complex clinical pathologies. The pathologies of these diseases are poorly understood and have no FDA-approved treatments leading to symptom management. Leigh syndrome (LS) is a pediatric mitochondrial disorder that affects the central nervous system during early development and causes death in infancy. Since there are no adequate models for understanding the rapid fatality associated with LS, human-induced pluripotent stem cell (hiPSC) technology has been recognized as a useful approach to generate patient-specific stem cells for disease modeling and understanding the origins of the phenotype. METHODS hiPSCs were generated from control BJ and four disease fibroblast lines using a cocktail of non-modified reprogramming and immune evasion mRNAs and microRNAs. Expression of hiPSC-associated intracellular and cell surface markers was identified by immunofluorescence and flow cytometry. Karyotyping of hiPSCs was performed with cytogenetic analysis. Sanger and next-generation sequencing were used to detect and quantify the mutation in all hiPSCs. The mitochondrial respiration ability and glycolytic function were measured by the Seahorse Bioscience XFe96 extracellular flux analyzer. RESULTS Reprogrammed hiPSCs expressed pluripotent stem cell markers including transcription factors POU5F1, NANOG and SOX2 and cell surface markers SSEA4, TRA-1-60 and TRA-1-81 at the protein level. Sanger sequencing analysis confirmed the presence of mutations in all reprogrammed hiPSCs. Next-generation sequencing demonstrated the variable presence of mutant mtDNA in reprogrammed hiPSCs. Cytogenetic analyses confirmed the presence of normal karyotype in all reprogrammed hiPSCs. Patient-derived hiPSCs demonstrated decreased maximal mitochondrial respiration, while mitochondrial ATP production was not significantly different between the control and disease hiPSCs. In line with low maximal respiration, the spare respiratory capacity was lower in all the disease hiPSCs. The hiPSCs also demonstrated neural and cardiac differentiation potential. CONCLUSION Overall, the hiPSCs exhibited variable mitochondrial dysfunction that may alter their differentiation potential and provide key insights into clinically relevant developmental perturbations.
Collapse
Affiliation(s)
- Fibi Meshrkey
- Department of Biological Sciences, J. William Fulbright College of Arts and Sciences, University of Arkansas, Science and Engineering 601, Fayetteville, AR, 72701, USA
- Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR, USA
- Department of Histology and Cell Biology, Faculty of Medicine, Alexandria University, Alexandria, Egypt
| | - Kelly M Scheulin
- Regenerative Bioscience Center, University of Georgia, Athens, GA, USA
- Department of Animal and Dairy Science, University of Georgia, Athens, GA, USA
- Neuroscience Program, Biomedical and Health Sciences Institute, University of Georgia, Athens, GA, USA
| | - Christopher M Littlejohn
- Regenerative Bioscience Center, University of Georgia, Athens, GA, USA
- Department of Animal and Dairy Science, University of Georgia, Athens, GA, USA
| | - Joshua Stabach
- Department of Biological Sciences, J. William Fulbright College of Arts and Sciences, University of Arkansas, Science and Engineering 601, Fayetteville, AR, 72701, USA
| | - Bibhuti Saikia
- Department of Biological Sciences, J. William Fulbright College of Arts and Sciences, University of Arkansas, Science and Engineering 601, Fayetteville, AR, 72701, USA
| | - Vedant Thorat
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Yimin Huang
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Thomas LaFramboise
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Edward J Lesnefsky
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA, USA
- Cardiology Section Medical Service, McGuire Veterans Affairs Medical Center, Richmond, VA, USA
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, VA, USA
- Division of Cardiology, Department of Internal Medicine, Pauley Heart Center, Virginia Commonwealth University, Richmond, VA, USA
| | - Raj R Rao
- Department of Biomedical Engineering, College of Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Franklin D West
- Regenerative Bioscience Center, University of Georgia, Athens, GA, USA
- Department of Animal and Dairy Science, University of Georgia, Athens, GA, USA
- Neuroscience Program, Biomedical and Health Sciences Institute, University of Georgia, Athens, GA, USA
| | - Shilpa Iyer
- Department of Biological Sciences, J. William Fulbright College of Arts and Sciences, University of Arkansas, Science and Engineering 601, Fayetteville, AR, 72701, USA.
- Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR, USA.
| |
Collapse
|
2
|
Meshrkey F, Cabrera Ayuso A, Rao RR, Iyer S. Quantitative analysis of mitochondrial morphologies in human induced pluripotent stem cells for Leigh syndrome. Stem Cell Res 2021; 57:102572. [PMID: 34662843 PMCID: PMC10332439 DOI: 10.1016/j.scr.2021.102572] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 10/03/2021] [Accepted: 10/11/2021] [Indexed: 01/19/2023] Open
Abstract
Mitochondria are dynamic organelles with wide range of morphologies contributing to regulating different signaling pathways and several cellular functions. Leigh syndrome (LS) is a classic pediatric mitochondrial disorder characterized by complex and variable clinical pathologies, and primarily affects the nervous system during early development. It is important to understand the differences between mitochondrial morphologies in healthy and diseased states so that focused therapies can target the disease during its early stages. In this study, we performed a comprehensive analysis of mitochondrial dynamics in five patient-derived human induced pluripotent stem cells (hiPSCs) containing different mutations associated with LS. Our results suggest that subtle alterations in mitochondrial morphologies are specific to the mtDNA variant. Three out of the five LS-hiPSCs exhibited characteristics consistent with fused mitochondria. To our knowledge, this is the first comprehensive study that quantifies mitochondrial dynamics in hiPSCs specific to mitochondrial disorders. In addition, we observed an overall decrease in mitochondrial membrane potential in all five LS-hiPSCs. A more thorough analysis of the correlations between mitochondrial dynamics, membrane potential dysfunction caused by mutations in the mtDNA in hiPSCs and differentiated derivatives will aid in identifying unique morphological signatures of various mitochondrial disorders during early stages of embryonic development.
Collapse
Affiliation(s)
- Fibi Meshrkey
- Department of Biological Sciences, Fulbright College of Arts and Sciences, University of Arkansas, Fayetteville, AR, USA; Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR, USA; Department of Histology and Cell Biology, Faculty of Medicine, Alexandria University, Egypt
| | - Ana Cabrera Ayuso
- Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR, USA
| | - Raj R Rao
- Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR, USA; Department of Biomedical Engineering, College of Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Shilpa Iyer
- Department of Biological Sciences, Fulbright College of Arts and Sciences, University of Arkansas, Fayetteville, AR, USA; Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR, USA.
| |
Collapse
|
3
|
Bakare AB, Dean J, Chen Q, Thorat V, Huang Y, LaFramboise T, Lesnefsky EJ, Iyer S. Evaluating the Bioenergetics Health Index Ratio in Leigh Syndrome Fibroblasts to Understand Disease Severity. Int J Mol Sci 2021; 22:ijms221910344. [PMID: 34638685 PMCID: PMC8508996 DOI: 10.3390/ijms221910344] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 09/23/2021] [Accepted: 09/23/2021] [Indexed: 12/21/2022] Open
Abstract
Several pediatric mitochondrial disorders, including Leigh syndrome (LS), impact mitochondrial (mt) genetics, development, and metabolism, leading to complex pathologies and energy failure. The extent to which pathogenic mtDNA variants regulate disease severity in LS is currently not well understood. To better understand this relationship, we computed a glycolytic bioenergetics health index (BHI) for measuring mitochondrial dysfunction in LS patient fibroblast cells harboring varying percentages of pathogenic mutant mtDNA (T8993G, T9185C) exhibiting deficiency in complex V or complex I (T10158C, T12706C). A high percentage (>90%) of pathogenic mtDNA in cells affecting complex V and a low percentage (<39%) of pathogenic mtDNA in cells affecting complex I was quantified. Levels of defective enzyme activities of the electron transport chain correlated with the percentage of pathogenic mtDNA. Subsequent bioenergetics assays showed cell lines relied on both OXPHOS and glycolysis for meeting energy requirements. Results suggest that whereas the precise mechanism of LS has not been elucidated, a multi-pronged approach taking into consideration the specific pathogenic mtDNA variant, glycolytic BHI, and the composite BHI (average ratio of oxphos to glycolysis) can aid in better understanding the factors influencing disease severity in LS.
Collapse
Affiliation(s)
- Ajibola B. Bakare
- Department of Biological Sciences, J. William Fulbright College of Arts and Sciences, University of Arkansas, Fayetteville, AR 72701, USA;
- Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR 72701, USA
| | - Joseph Dean
- Cardiology Section Medical Service, McGuire Veterans Affairs Medical Center, Richmond, VA 23284, USA; (J.D.); (E.J.L.)
| | - Qun Chen
- Pauley Heart Center, Division of Cardiology, Department of Internal Medicine, Virginia Commonwealth University, Richmond, VA 23284, USA;
| | - Vedant Thorat
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA; (V.T.); (Y.H.); (T.L.)
| | - Yimin Huang
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA; (V.T.); (Y.H.); (T.L.)
| | - Thomas LaFramboise
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA; (V.T.); (Y.H.); (T.L.)
| | - Edward J. Lesnefsky
- Cardiology Section Medical Service, McGuire Veterans Affairs Medical Center, Richmond, VA 23284, USA; (J.D.); (E.J.L.)
- Pauley Heart Center, Division of Cardiology, Department of Internal Medicine, Virginia Commonwealth University, Richmond, VA 23284, USA;
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, VA 23219, USA
| | - Shilpa Iyer
- Department of Biological Sciences, J. William Fulbright College of Arts and Sciences, University of Arkansas, Fayetteville, AR 72701, USA;
- Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR 72701, USA
- Correspondence: ; Tel.: +1-(479)-575-3400
| |
Collapse
|
4
|
Ni Y, Hagras MA, Konstantopoulou V, Mayr JA, Stuchebrukhov AA, Meierhofer D. Mutations in NDUFS1 Cause Metabolic Reprogramming and Disruption of the Electron Transfer. Cells 2019; 8:cells8101149. [PMID: 31557978 PMCID: PMC6829531 DOI: 10.3390/cells8101149] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 09/10/2019] [Accepted: 09/20/2019] [Indexed: 01/07/2023] Open
Abstract
Complex I (CI) is the first enzyme of the mitochondrial respiratory chain and couples the electron transfer with proton pumping. Mutations in genes encoding CI subunits can frequently cause inborn metabolic errors. We applied proteome and metabolome profiling of patient-derived cells harboring pathogenic mutations in two distinct CI genes to elucidate underlying pathomechanisms on the molecular level. Our results indicated that the electron transfer within CI was interrupted in both patients by different mechanisms. We showed that the biallelic mutations in NDUFS1 led to a decreased stability of the entire N-module of CI and disrupted the electron transfer between two iron–sulfur clusters. Strikingly interesting and in contrast to the proteome, metabolome profiling illustrated that the pattern of dysregulated metabolites was almost identical in both patients, such as the inhibitory feedback on the TCA cycle and altered glutathione levels, indicative for reactive oxygen species (ROS) stress. Our findings deciphered pathological mechanisms of CI deficiency to better understand inborn metabolic errors.
Collapse
Affiliation(s)
- Yang Ni
- Mass Spectrometry Facility, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany;
- Department of Biology, Chemistry and Pharmacy, Freie Universität Berlin, 14195 Berlin, Germany
- Present address: Laboratory of Angiogenesis and Vascular Metabolism, VIB-KU Leuven Center for Cancer Biology, 3000 Leuven, Belgium
| | - Muhammad A. Hagras
- Department of Chemistry, University of California Davis, Davis, CA 95616, USA; (M.A.H.); (A.A.S.)
- Present address: Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Vassiliki Konstantopoulou
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, 1090 Vienna, Austria;
| | - Johannes A. Mayr
- Department of Pediatrics, Paracelsus Medical University Salzburg, 5020 Salzburg, Austria;
| | - Alexei A. Stuchebrukhov
- Department of Chemistry, University of California Davis, Davis, CA 95616, USA; (M.A.H.); (A.A.S.)
| | - David Meierhofer
- Mass Spectrometry Facility, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany;
- Correspondence: ; Tel.: +49-30-8413-1567
| |
Collapse
|
5
|
Piotrowska-Nowak A, Kosior-Jarecka E, Schab A, Wrobel-Dudzinska D, Bartnik E, Zarnowski T, Tonska K. Investigation of whole mitochondrial genome variation in normal tension glaucoma. Exp Eye Res 2018; 178:186-197. [PMID: 30312593 DOI: 10.1016/j.exer.2018.10.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 08/16/2018] [Accepted: 10/08/2018] [Indexed: 01/06/2023]
Abstract
Glaucoma is one of the leading causes of visual impairment and blindness worldwide. However, the cause of retinal ganglion cell loss and damage of the optic nerve in its pathogenesis is largely unknown. The high energy demands of these cells may reflect their strong dependence on mitochondrial function and thus sensitivity to mitochondrial defects. To address this issue, we studied whole mitochondrial genome variation in normal tension glaucoma patients and control individuals from the Polish population using next generation sequencing. Our findings indicate that few features of mitochondrial DNA variation are different for glaucoma patients and control subjects. New insights into normal tension glaucoma development are discussed. We provide also a comprehensive approach for mitochondrial DNA analysis and variant evaluation.
Collapse
Affiliation(s)
- Agnieszka Piotrowska-Nowak
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Pawinskiego 5a Street, Warsaw, 02-106, Poland.
| | - Ewa Kosior-Jarecka
- Department of Diagnostics and Microsurgery of Glaucoma, Medical University of Lublin, Chmielna 1 Street, Lublin, 20-079, Poland.
| | - Aleksandra Schab
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Pawinskiego 5a Street, Warsaw, 02-106, Poland.
| | - Dominika Wrobel-Dudzinska
- Department of Diagnostics and Microsurgery of Glaucoma, Medical University of Lublin, Chmielna 1 Street, Lublin, 20-079, Poland.
| | - Ewa Bartnik
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Pawinskiego 5a Street, Warsaw, 02-106, Poland; Institute of Biochemistry and Biophysics Polish Academy of Sciences, Pawinskiego 5a Street, Warsaw, 02-106, Poland.
| | - Tomasz Zarnowski
- Department of Diagnostics and Microsurgery of Glaucoma, Medical University of Lublin, Chmielna 1 Street, Lublin, 20-079, Poland.
| | - Katarzyna Tonska
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Pawinskiego 5a Street, Warsaw, 02-106, Poland.
| |
Collapse
|
6
|
Sallevelt SCEH, de Die-Smulders CEM, Hendrickx ATM, Hellebrekers DMEI, de Coo IFM, Alston CL, Knowles C, Taylor RW, McFarland R, Smeets HJM. De novo mtDNA point mutations are common and have a low recurrence risk. J Med Genet 2016; 54:73-83. [PMID: 27450679 PMCID: PMC5502310 DOI: 10.1136/jmedgenet-2016-103876] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 06/02/2016] [Accepted: 06/09/2016] [Indexed: 12/25/2022]
Abstract
Background Severe, disease-causing germline mitochondrial (mt)DNA mutations are maternally inherited or arise de novo. Strategies to prevent transmission are generally available, but depend on recurrence risks, ranging from high/unpredictable for many familial mtDNA point mutations to very low for sporadic, large-scale single mtDNA deletions. Comprehensive data are lacking for de novo mtDNA point mutations, often leading to misconceptions and incorrect counselling regarding recurrence risk and reproductive options. We aim to study the relevance and recurrence risk of apparently de novo mtDNA point mutations. Methods Systematic study of prenatal diagnosis (PND) and recurrence of mtDNA point mutations in families with de novo cases, including new and published data. ‘De novo’ based on the absence of the mutation in multiple (postmitotic) maternal tissues is preferred, but mutations absent in maternal blood only were also included. Results In our series of 105 index patients (33 children and 72 adults) with (likely) pathogenic mtDNA point mutations, the de novo frequency was 24.6%, the majority being paediatric. PND was performed in subsequent pregnancies of mothers of four de novo cases. A fifth mother opted for preimplantation genetic diagnosis because of a coexisting Mendelian genetic disorder. The mtDNA mutation was absent in all four prenatal samples and all 11 oocytes/embryos tested. A literature survey revealed 137 de novo cases, but PND was only performed for 9 (including 1 unpublished) mothers. In one, recurrence occurred in two subsequent pregnancies, presumably due to germline mosaicism. Conclusions De novo mtDNA point mutations are a common cause of mtDNA disease. Recurrence risk is low. This is relevant for genetic counselling, particularly for reproductive options. PND can be offered for reassurance.
Collapse
Affiliation(s)
- Suzanne C E H Sallevelt
- Department of Clinical Genetics, Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands
| | - Christine E M de Die-Smulders
- Department of Clinical Genetics, Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands.,Research School for Developmental Biology (GROW), Maastricht University, Maastricht, The Netherlands
| | - Alexandra T M Hendrickx
- Department of Clinical Genetics, Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands
| | - Debby M E I Hellebrekers
- Department of Clinical Genetics, Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands
| | - Irenaeus F M de Coo
- Department of Neurology, Erasmus MC-Sophia Children's Hospital Rotterdam, Rotterdam, The Netherlands
| | - Charlotte L Alston
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Charlotte Knowles
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Robert W Taylor
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Robert McFarland
- Wellcome Trust Centre for Mitochondrial Research, Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Hubert J M Smeets
- Department of Clinical Genetics, Maastricht University Medical Centre (MUMC), Maastricht, The Netherlands.,Research School for Developmental Biology (GROW), Maastricht University, Maastricht, The Netherlands.,Research School for Cardiovascular Diseases in Maastricht, CARIM, Maastricht University, Maastricht, The Netherlands
| |
Collapse
|
7
|
Pronicka E, Piekutowska-Abramczuk D, Ciara E, Trubicka J, Rokicki D, Karkucińska-Więckowska A, Pajdowska M, Jurkiewicz E, Halat P, Kosińska J, Pollak A, Rydzanicz M, Stawinski P, Pronicki M, Krajewska-Walasek M, Płoski R. New perspective in diagnostics of mitochondrial disorders: two years' experience with whole-exome sequencing at a national paediatric centre. J Transl Med 2016; 14:174. [PMID: 27290639 PMCID: PMC4903158 DOI: 10.1186/s12967-016-0930-9] [Citation(s) in RCA: 157] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 05/31/2016] [Indexed: 12/30/2022] Open
Abstract
Background Whole-exome sequencing (WES) has led to an exponential increase in identification of causative variants in mitochondrial disorders (MD). Methods We performed WES in 113 MD suspected patients from Polish paediatric reference centre, in whom routine testing failed to identify a molecular defect. WES was performed using TruSeqExome enrichment, followed by variant prioritization, validation by Sanger sequencing, and segregation with the disease phenotype in the family. Results Likely causative mutations were identified in 67 (59.3 %) patients; these included variants in mtDNA (6 patients) and nDNA: X-linked (9 patients), autosomal dominant (5 patients), and autosomal recessive (47 patients, 11 homozygotes). Novel variants accounted for 50.5 % (50/99) of all detected changes. In 47 patients, changes in 31 MD-related genes (ACAD9, ADCK3, AIFM1, CLPB, COX10, DLD, EARS2, FBXL4, MTATP6, MTFMT, MTND1, MTND3, MTND5, NAXE, NDUFS6, NDUFS7, NDUFV1, OPA1, PARS2, PC, PDHA1, POLG, RARS2, RRM2B, SCO2, SERAC1, SLC19A3, SLC25A12, TAZ, TMEM126B, VARS2) were identified. The ACAD9, CLPB, FBXL4, PDHA1 genes recurred more than twice suggesting higher general/ethnic prevalence. In 19 cases, variants in 18 non-MD related genes (ADAR, CACNA1A, CDKL5, CLN3, CPS1, DMD, DYSF, GBE1, GFAP, HSD17B4, MECP2, MYBPC3, PEX5, PGAP2, PIGN, PRF1, SBDS, SCN2A) were found. The percentage of positive WES results rose gradually with increasing probability of MD according to the Mitochondrial Disease Criteria (MDC) scale (from 36 to 90 % for low and high probability, respectively). The percentage of detected MD-related genes compared with non MD-related genes also grew with the increasing MD likelihood (from 20 to 97 %). Molecular diagnosis was established in 30/47 (63.8 %) neonates and in 17/28 (60.7 %) patients with basal ganglia involvement. Mutations in CLPB, SERAC1, TAZ genes were identified in neonates with 3-methylglutaconic aciduria (3-MGA) as a discriminative feature. New MD-related candidate gene (NDUFB8) is under verification. Conclusions We suggest WES rather than targeted NGS as the method of choice in diagnostics of MD in children, including neonates with 3-MGA aciduria, who died without determination of disease cause and with limited availability of laboratory data. There is a strong correlation between the degree of MD diagnosis by WES and MD likelihood expressed by the MDC scale. Electronic supplementary material The online version of this article (doi:10.1186/s12967-016-0930-9) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Ewa Pronicka
- Department of Medical Genetics, The Children's Memorial Health Institute, 04-730, Warsaw, Poland. .,Department of Paediatrics, Nutrition and Metabolic Diseases,, The Children's Memorial Health Institute, Warsaw, Poland.
| | | | - Elżbieta Ciara
- Department of Medical Genetics, The Children's Memorial Health Institute, 04-730, Warsaw, Poland
| | - Joanna Trubicka
- Department of Medical Genetics, The Children's Memorial Health Institute, 04-730, Warsaw, Poland
| | - Dariusz Rokicki
- Department of Paediatrics, Nutrition and Metabolic Diseases,, The Children's Memorial Health Institute, Warsaw, Poland
| | | | - Magdalena Pajdowska
- Department of Biochemistry and Experimental Medicine, The Children's Memorial Health Institute, Warsaw, Poland
| | - Elżbieta Jurkiewicz
- Department of Radiology, The Children's Memorial Health Institute, Warsaw, Poland
| | - Paulina Halat
- Department of Medical Genetics, The Children's Memorial Health Institute, 04-730, Warsaw, Poland
| | - Joanna Kosińska
- Department of Medical Genetics, Warsaw Medical University, Pawińskiego str, 02-106, Warsaw, Poland
| | - Agnieszka Pollak
- Department of Genetics, Institute of Physiology and Pathology of Hearing, Nadarzyn, Poland
| | - Małgorzata Rydzanicz
- Department of Medical Genetics, Warsaw Medical University, Pawińskiego str, 02-106, Warsaw, Poland
| | - Piotr Stawinski
- Department of Genetics, Institute of Physiology and Pathology of Hearing, Nadarzyn, Poland
| | - Maciej Pronicki
- Department of Pathology, The Children's Memorial Health Institute, Warsaw, Poland
| | | | - Rafał Płoski
- Department of Medical Genetics, Warsaw Medical University, Pawińskiego str, 02-106, Warsaw, Poland.
| |
Collapse
|
8
|
Cation transport by the respiratory NADH:quinone oxidoreductase (complex I): facts and hypotheses. Biochem Soc Trans 2014; 41:1280-7. [PMID: 24059520 DOI: 10.1042/bst20130024] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The respiratory complex I (electrogenic NADH:quinone oxidoreductase) has been considered to act exclusively as a H+ pump. This was questioned when the search for the NADH-driven respiratory Na+ pump in Klebsiella pneumoniae initiated by Peter Dimroth led to the discovery of a Na+-translocating complex in this enterobacterium. The 3D structures of complex I from different organisms support the idea that the mechanism of cation transport by complex I involves conformational changes of the membrane-bound NuoL, NuoM and NuoN subunits. In vitro methods to follow Na+ transport were compared with in vivo approaches to test whether complex I, or its individual NuoL, NuoM or NuoN subunits, extrude Na+ from the cytoplasm to the periplasm of bacterial host cells. The truncated NuoL subunit of the Escherichia coli complex I which comprises amino acids 1-369 exhibits Na+ transport activity in vitro. This observation, together with an analysis of putative cation channels in NuoL, suggests that there exists in NuoL at least one continuous pathway for cations lined by amino acid residues from transmembrane segments 3, 4, 5, 7 and 8. Finally, we discuss recent studies on Na+ transport by mitochondrial complex I with respect to its putative role in the cycling of Na+ ions across the inner mitochondrial membrane.
Collapse
|
9
|
Import of desired nucleic acid sequences using addressing motif of mitochondrial ribosomal 5S-rRNA for fluorescent in vivo hybridization of mitochondrial DNA and RNA. J Bioenerg Biomembr 2014; 46:147-56. [PMID: 24562889 DOI: 10.1007/s10863-014-9543-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Accepted: 01/29/2014] [Indexed: 12/28/2022]
Abstract
Based on the matrix-addressing sequence of mitochondrial ribosomal 5S-rRNA (termed MAM), which is naturally imported into mitochondria, we have constructed an import system for in vivo targeting of mitochondrial DNA (mtDNA) or mt-mRNA, in order to provide fluorescence hybridization of the desired sequences. Thus DNA oligonucleotides were constructed, containing the 5'-flanked T7 RNA polymerase promoter. After in vitro transcription and fluorescent labeling with Alexa Fluor(®) 488 or 647 dye, we obtained the fluorescent "L-ND5 probe" containing MAM and exemplar cargo, i.e., annealing sequence to a short portion of ND5 mRNA and to the light-strand mtDNA complementary to the heavy strand nd5 mt gene (5'-end 21 base pair sequence). For mitochondrial in vivo fluorescent hybridization, HepG2 cells were treated with dequalinium micelles, containing the fluorescent probes, bringing the probes proximally to the mitochondrial outer membrane and to the natural import system. A verification of import into the mitochondrial matrix of cultured HepG2 cells was provided by confocal microscopy colocalizations. Transfections using lipofectamine or probes without 5S-rRNA addressing MAM sequence or with MAM only were ineffective. Alternatively, the same DNA oligonucleotides with 5'-CACC overhang (substituting T7 promoter) were transcribed from the tetracycline-inducible pENTRH1/TO vector in human embryonic kidney T-REx®-293 cells, while mitochondrial matrix localization after import of the resulting unlabeled RNA was detected by PCR. The MAM-containing probe was then enriched by three-order of magnitude over the natural ND5 mRNA in the mitochondrial matrix. In conclusion, we present a proof-of-principle for mitochondrial in vivo hybridization and mitochondrial nucleic acid import.
Collapse
|
10
|
Calatayud M, Ramos A, Santos C, Aluja MP. Primer effect in the detection of mitochondrial DNA point heteroplasmy by automated sequencing. ACTA ACUST UNITED AC 2013; 24:303-11. [PMID: 23350969 DOI: 10.3109/19401736.2012.760072] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The correct detection of mitochondrial DNA (mtDNA) heteroplasmy by automated sequencing presents methodological constraints. The main goals of this study are to investigate the effect of sense and distance of primers in heteroplasmy detection and to test if there are differences in the accurate determination of heteroplasmy involving transitions or transversions. A gradient of the heteroplasmy levels was generated for mtDNA positions 9477 (transition G/A) and 15,452 (transversion C/A). Amplification and subsequent sequencing with forward and reverse primers, situated at 550 and 150 bp from the heteroplasmic positions, were performed. Our data provide evidence that there is a significant difference between the use of forward and reverse primers. The forward primer is the primer that seems to give a better approximation to the real proportion of the variants. No significant differences were found concerning the distance at which the sequencing primers were placed neither between the analysis of transitions and transversions. The data collected in this study are a starting point that allows to glimpse the importance of the sequencing primers in the accurate detection of point heteroplasmy, providing additional insight into the overall automated sequencing strategy.
Collapse
Affiliation(s)
- Marta Calatayud
- Unitat d'Antropologia Biològica, Departament BABVE, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Barcelona, Spain
| | | | | | | |
Collapse
|
11
|
An inherited heteroplasmic mutation in mitochondrial gene COI in a patient with prostate cancer alters reactive oxygen, reactive nitrogen and proliferation. BIOMED RESEARCH INTERNATIONAL 2012; 2013:239257. [PMID: 23509693 PMCID: PMC3591245 DOI: 10.1155/2013/239257] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 08/08/2012] [Accepted: 08/09/2012] [Indexed: 11/23/2022]
Abstract
Mitochondrial DNA (mtDNA) mutations have been found in many cancers but the physiological derangements caused by such mutations have remained elusive. Prostate cancer is associated with both inherited and somatic mutations in the cytochrome c oxidase (COI) gene. We present a prostate cancer patient-derived rare heteroplasmic mutation of this gene, part of mitochondrial respiratory complex IV. Functional studies indicate that this mutation leads to the simultaneous decrease in cytochrome oxidation, increase in reactive oxygen, and increased reactive nitrogen. These data suggest that mitochondrial DNA mutations resulting in increased reactive oxygen and reactive nitrogen generation may be involved in prostate cancer biology.
Collapse
|
12
|
Chamkha I, Alila-Fersi O, Mkaouar-Rebai E, Aloulou H, Kifagi C, Hachicha M, Fakhfakh F. A novel m.12908T>A mutation in the mitochondrial ND5 gene in patient with infantile-onset Pompe disease. Biochem Biophys Res Commun 2012; 429:31-8. [DOI: 10.1016/j.bbrc.2012.10.105] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Accepted: 10/11/2012] [Indexed: 01/10/2023]
|
13
|
Zhang X, Xiao Z, Liu X, Du L, Wang L, Wang S, Zheng N, Zheng G, Li W, Zhang X, Dong Z, Zhuang X, Wang C. The potential role of ORM2 in the development of colorectal cancer. PLoS One 2012; 7:e31868. [PMID: 22363757 PMCID: PMC3283705 DOI: 10.1371/journal.pone.0031868] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Accepted: 01/13/2012] [Indexed: 12/15/2022] Open
Abstract
Colorectal cancer (CRC) is the third most common malignancy in the world. The risk of death is closely correlated to the stage of CRC at the time of primary diagnosis. Therefore, there is a compelling need for the identification of blood biomarkers that can enable early detection of CRC. We used a quantitative proteomic approach with isobaric labeling (iTRAQ) to examine changes in the plasma proteome of 10 patients with CRC compared to healthy volunteers. Enzyme-Linked Immunosorbnent Assay (ELISA) and Western blot were used for further validation. In our quantitative proteomics analysis, we detected 75 human plasma proteins with more than 95% confidence using iTRAQ labeling in conjunction with microQ-TOF MS. 9 up-regulated and 4 down-regulated proteins were observed in the CRC group. The ORM2 level in plasma was confirmed to be significantly elevated in patients suffering from CRC compared with the controls. ORM2 expression in CRC tissues was significantly increased compared with that in corresponding adjacent normal mucous tissues (P<0.001). ITRAQ together with Q-TOF/MS is a sensitive and reproducible technique of quantitative proteomics. Alteration in expression of ORM2 suggests that ORM2 could be used as a potential biomarker in the diagnosis of CRC.
Collapse
Affiliation(s)
- Xuhua Zhang
- Department of Clinical Laboratory, Qilu Hospital, Shandong University, Jinan, Shandong, China
- Department of Clinical Laboratory, The Second Hospital, Shandong University, Jinan, Shandong, China
| | - Zhiying Xiao
- Department of Urology, The Second Hospital, Shandong University, Jinan, Shandong, China
| | - Xiaoyong Liu
- Department of Biology, McGill University, Montreal, Quebec, Canada
| | - Lutao Du
- Department of Clinical Laboratory, Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Lili Wang
- Department of Clinical Laboratory, Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Shun Wang
- Department of Clinical Laboratory, Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Ni Zheng
- Department of Clinical Laboratory, Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Guixi Zheng
- Department of Clinical Laboratory, Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Wei Li
- Department of Clinical Laboratory, Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Xin Zhang
- Department of Clinical Laboratory, Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Zhaogang Dong
- Department of Clinical Laboratory, Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Xuewei Zhuang
- Department of Clinical Laboratory, Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Chuanxin Wang
- Department of Clinical Laboratory, Qilu Hospital, Shandong University, Jinan, Shandong, China
- * E-mail:
| |
Collapse
|
14
|
Jezek P, Plecitá-Hlavatá L. Mitochondrial reticulum network dynamics in relation to oxidative stress, redox regulation, and hypoxia. Int J Biochem Cell Biol 2009; 41:1790-804. [PMID: 19703650 DOI: 10.1016/j.biocel.2009.02.014] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Revised: 02/17/2009] [Accepted: 02/19/2009] [Indexed: 02/03/2023]
Abstract
A single mitochondrial network in the cell undergoes constant fission and fusion primarily depending on the local GTP gradients and the mitochondrial energetics. Here we overview the main properties and regulation of pro-fusion and pro-fission mitodynamins, i.e. dynamins-related GTPases responsible for mitochondrial shape-forming, such as pro-fusion mitofusins MFN1, MFN2, and the inner membrane-residing long OPA1 isoforms, and pro-fission mitodynamins FIS1, MFF, and DRP1 multimers required for scission. Notably, the OPA1 cleavage into non-functional short isoforms at a diminished ATP level (collapsed membrane potential) and the DRP1 recruitment upon phosphorylation by various kinases are overviewed. Possible responses of mitodynamins to the oxidative stress, hypoxia, and concomitant mtDNA mutations are also discussed. We hypothesize that the increased GTP formation within the Krebs cycle followed by the GTP export via the ADP/ATP carrier shift the balance between fission and fusion towards fusion by activating the GTPase domain of OPA1 located in the peripheral intermembrane space (PIMS). Since the protein milieu of PIMS is kept at the prevailing oxidized redox potential by the TOM, MIA40 and ALR/Erv1 import-redox trapping system, redox regulations shift the protein environment of PIMS to a more reduced state due to the higher substrate load and increased respiration. A higher cytochrome c turnover rate may prevent electron transfer from ALR/Erv1 to cytochrome c. Nevertheless, the putative links between the mitodynamin responses, mitochondrial morphology and the changes in the mitochondrial bioenergetics, superoxide production, and hypoxia are yet to be elucidated, including the precise basis for signaling by the mitochondrion-derived vesicles.
Collapse
Affiliation(s)
- Petr Jezek
- Department of Membrane Transport Biophysics, No. 75, Institute of Physiology, v.v.i., Academy of Sciences of the Czech Republic, Vídenská 1083, CZ 14220 Prague, Czech Republic.
| | | |
Collapse
|
15
|
Abstract
Leigh syndrome (also termed subacute, necrotizing encephalopathy) is a devastating neurodegenerative disorder, characterized by almost identical brain changes, e.g., focal, bilaterally symmetric lesions, particularly in the basal ganglia, thalamus, and brainstem, but with considerable clinical and genetic heterogeneity. Clinically, Leigh syndrome is characterized by a wide variety of abnormalities, from severe neurologic problems to a near absence of abnormalities. Most frequently the central nervous system is affected, with psychomotor retardation, seizures, nystagmus, ophthalmoparesis, optic atrophy, ataxia, dystonia, or respiratory failure. Some patients also present with peripheral nervous system involvement, including polyneuropathy or myopathy, or non-neurologic abnormalities, e.g., diabetes, short stature, hypertrichosis, cardiomyopathy, anemia, renal failure, vomiting, or diarrhea (Leigh-like syndrome). In the majority of cases, onset is in early childhood, but in a small number of cases, adults are affected. In the majority of cases, dysfunction of the respiratory chain (particularly complexes I, II, IV, or V), of coenzyme Q, or of the pyruvate dehydrogenase complex are responsible for the disease. Associated mutations affect genes of the mitochondrial or nuclear genome. Leigh syndrome and Leigh-like syndrome are the mitochondrial disorders with the largest genetic heterogeneity.
Collapse
|
16
|
Bamne MN, Talkowski ME, Moraes CT, Manuck SB, Ferrell RE, Chowdari KV, Nimgaonkar VL. Systematic association studies of mitochondrial DNA variations in schizophrenia: focus on the ND5 gene. Schizophr Bull 2008; 34:458-65. [PMID: 17898419 PMCID: PMC2632438 DOI: 10.1093/schbul/sbm100] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Postmortem studies, as well as genetic association studies, have implicated mitochondrial dysfunction in schizophrenia (SZ). We conducted multistaged analysis to assess the involvement of mitochondrial DNA (mtDNA) variations in SZ. Initially, the entire mtDNA genome was sequenced in pools of DNA from SZ cases and controls (n = 180 in each group, set 1). Two polymorphisms localized to the NADH dehydrogenase subunit 5 (ND5) gene demonstrated suggestive case control allele frequency differences (mtDNA 13368 G/A, p = .019 and mtDNA 13708G/A, p = .043). Hence, the ND5 gene was sequenced in individual samples from the initial panel of cases and controls. Additional subjects from another independent set of cases and controls (set 2, cases, n = 244, controls n = 508) were also sequenced individually. No significant differences in allele frequencies for mtDNA 13368 G/A, and mtDNA 13708G/A were observed. However, we identified 216 other rare variants, 53 of which were reported earlier in association studies of other mitochondrial disorders. We compared the distribution of polymorphisms in both sets of cases and controls. No significant case-control differences were observed in the smaller, first set. In the second set, cases had more variants overall (p = 0.014), as well as synonymous variants (p = 0.02), but the difference for nonsynonymous variants was not significant (p = 0.19). Screening available first-degree relatives (n = 10) revealed 10 maternally inherited variations, suggesting that not all the variants are somatic mutations. Further investigations are warranted.
Collapse
Affiliation(s)
- Mikhil N. Bamne
- Department of Psychiatry, University of Pittsburgh School of Medicine, Western Psychiatric Institute and Clinic, University of Pittsburgh, 3811 O'Hara Street, Pittsburgh, PA 15213
| | - Michael E. Talkowski
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15213
| | - Carlos T. Moraes
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136
| | - Stephen B. Manuck
- Department of Psychology, University of Pittsburgh, Pittsburgh, PA 15213
| | - Robert E. Ferrell
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15213
| | - Kodavali V. Chowdari
- Department of Psychiatry, University of Pittsburgh School of Medicine, Western Psychiatric Institute and Clinic, University of Pittsburgh, 3811 O'Hara Street, Pittsburgh, PA 15213
| | - Vishwajit L. Nimgaonkar
- To whom correspondence should be addressed; Department of Psychiatry and Human Genetics, University of Pittsburgh School of Medicine and Graduate School of Public Health, Western Psychiatric Institute and Clinic, Room 443, Western Psychiatric Institute and Clinic, University of Pittsburgh, 3811 O'Hara Street, Pittsburgh, PA 15213; tel: 412-246-6353, fax: 412-246-6350, e-mail:
| |
Collapse
|
17
|
Dlasková A, Hlavatá L, Jezek J, Jezek P. Mitochondrial Complex I superoxide production is attenuated by uncoupling. Int J Biochem Cell Biol 2008; 40:2098-109. [PMID: 18358763 DOI: 10.1016/j.biocel.2008.02.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2007] [Revised: 02/07/2008] [Accepted: 02/11/2008] [Indexed: 12/16/2022]
Abstract
Complex I, i.e. proton-pumping NADH:quinone oxidoreductase, is an essential component of the mitochondrial respiratory chain but produces superoxide as a side-reaction. However, conditions for maximum superoxide production or its attenuation are not well understood. Unlike for Complex III, it has not been clear whether a Complex I-derived superoxide generation at forward electron transport is sensitive to membrane potential or protonmotive force. In order to investigate this, we used Amplex Red for H(2)O(2) monitoring, assessing the total mitochondrial superoxide production in isolated rat liver mitochondria respiring at state 4 as well as at state 3, namely with exclusive Complex I substrates or with Complex I substrates plus succinate. We have shown for the first time, that uncoupling diminishes rotenone-induced H(2)O(2) production also in state 3, while similar attenuation was observed in state 4. Moreover, we have found that 5-(N-ethyl-N-isopropyl) amiloride is a real inhibitor of Complex I H(+) pumping (IC(50) of 27 microM) without affecting respiration. It also partially prevented suppression by FCCP of rotenone-induced H(2)O(2) production with Complex I substrates alone (glutamate and malate), but nearly completely with Complexes I and II substrates. Sole 5-(N-ethyl-N-isopropyl) amiloride alone suppressed 20% and 30% of total H(2)O(2) production, respectively, under these conditions. Our data suggest that Complex I mitochondrial superoxide production can be attenuated by uncoupling, which means by acceleration of Complex I H(+) pumping due to the respiratory control. However, when this acceleration is prevented by 5-(N-ethyl-N-isopropyl) amiloride inhibition, no attenuation of superoxide production takes place.
Collapse
Affiliation(s)
- Andrea Dlasková
- Department of Membrane Transport Biophysics, No. 75, Institute of Physiology, Academy of Sciences of the Czech Republic, Vídenská 1083, Prague 14220, Czech Republic.
| | | | | | | |
Collapse
|
18
|
Cardol P, Boutaffala L, Memmi S, Devreese B, Matagne RF, Remacle C. In Chlamydomonas, the loss of ND5 subunit prevents the assembly of whole mitochondrial complex I and leads to the formation of a low abundant 700 kDa subcomplex. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:388-96. [PMID: 18258177 DOI: 10.1016/j.bbabio.2008.01.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2007] [Revised: 12/26/2007] [Accepted: 01/08/2008] [Indexed: 10/22/2022]
Abstract
In the green alga Chlamydomonas reinhardtii, a mutant deprived of complex I enzyme activity presents a 1T deletion in the mitochondrial nd5 gene. The loss of the ND5 subunit prevents the assembly of the 950 kDa whole complex I. Instead, a low abundant 700 kDa subcomplex, loosely associated to the inner mitochondrial membrane, is assembled. The resolution of the subcomplex by SDS-PAGE gave rise to 19 individual spots, sixteen having been identified by mass spectrometry analysis. Eleven, mainly associated to the hydrophilic part of the complex, are homologs to subunits of the bovine enzyme whereas five (including gamma-type carbonic anhydrase subunits) are specific to green plants or to plants and fungi. None of the subunits typical of the beta membrane domain of complex I enzyme has been identified in the mutant. This allows us to propose that the truncated enzyme misses the membrane distal domain of complex I but retains the proximal domain associated to the matrix arm of the enzyme. A complex I topology model is presented in the light of our results. Finally, a supercomplex most probably corresponding to complex I-complex III association, was identified in mutant mitochondria, indicating that the missing part of the enzyme is not required for the formation of the supercomplex.
Collapse
Affiliation(s)
- Pierre Cardol
- Genetics of Microorganisms, Department of Life Sciences, B22, University of Liège, B-4000 Liège, Belgium.
| | | | | | | | | | | |
Collapse
|