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Baker ZN, Forny P, Pagliarini DJ. Mitochondrial proteome research: the road ahead. Nat Rev Mol Cell Biol 2024; 25:65-82. [PMID: 37773518 DOI: 10.1038/s41580-023-00650-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/08/2023] [Indexed: 10/01/2023]
Abstract
Mitochondria are multifaceted organelles with key roles in anabolic and catabolic metabolism, bioenergetics, cellular signalling and nutrient sensing, and programmed cell death processes. Their diverse functions are enabled by a sophisticated set of protein components encoded by the nuclear and mitochondrial genomes. The extent and complexity of the mitochondrial proteome remained unclear for decades. This began to change 20 years ago when, driven by the emergence of mass spectrometry-based proteomics, the first draft mitochondrial proteomes were established. In the ensuing decades, further technological and computational advances helped to refine these 'maps', with current estimates of the core mammalian mitochondrial proteome ranging from 1,000 to 1,500 proteins. The creation of these compendia provided a systemic view of an organelle previously studied primarily in a reductionist fashion and has accelerated both basic scientific discovery and the diagnosis and treatment of human disease. Yet numerous challenges remain in understanding mitochondrial biology and translating this knowledge into the medical context. In this Roadmap, we propose a path forward for refining the mitochondrial protein map to enhance its discovery and therapeutic potential. We discuss how emerging technologies can assist the detection of new mitochondrial proteins, reveal their patterns of expression across diverse tissues and cell types, and provide key information on proteoforms. We highlight the power of an enhanced map for systematically defining the functions of its members. Finally, we examine the utility of an expanded, functionally annotated mitochondrial proteome in a translational setting for aiding both diagnosis of mitochondrial disease and targeting of mitochondria for treatment.
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Affiliation(s)
- Zakery N Baker
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Patrick Forny
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, USA
| | - David J Pagliarini
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, USA.
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA.
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA.
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Wojcik MH, Lemire G, Zaki MS, Wissman M, Win W, White S, Weisburd B, Waddell LB, Verboon JM, VanNoy GE, Töpf A, Tan TY, Straub V, Stenton SL, Snow H, Singer-Berk M, Silver J, Shril S, Seaby EG, Schneider R, Sankaran VG, Sanchis-Juan A, Russell KA, Reinson K, Ravenscroft G, Pierce EA, Place EM, Pajusalu S, Pais L, Õunap K, Osei-Owusu I, Okur V, Oja KT, O'Leary M, O'Heir E, Morel C, Marchant RG, Mangilog BE, Madden JA, MacArthur D, Lovgren A, Lerner-Ellis JP, Lin J, Laing N, Hildebrandt F, Groopman E, Goodrich J, Gleeson JG, Ghaoui R, Genetti CA, Gazda HT, Ganesh VS, Ganapathy M, Gallacher L, Fu J, Evangelista E, England E, Donkervoort S, DiTroia S, Cooper ST, Chung WK, Christodoulou J, Chao KR, Cato LD, Bujakowska KM, Bryen SJ, Brand H, Bonnemann C, Beggs AH, Baxter SM, Agrawal PB, Talkowski M, Austin-Tse C, Rehm HL, O'Donnell-Luria A. Unique Capabilities of Genome Sequencing for Rare Disease Diagnosis. medRxiv 2023:2023.08.08.23293829. [PMID: 38328047 PMCID: PMC10849673 DOI: 10.1101/2023.08.08.23293829] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Background Causal variants underlying rare disorders may remain elusive even after expansive gene panels or exome sequencing (ES). Clinicians and researchers may then turn to genome sequencing (GS), though the added value of this technique and its optimal use remain poorly defined. We therefore investigated the advantages of GS within a phenotypically diverse cohort. Methods GS was performed for 744 individuals with rare disease who were genetically undiagnosed. Analysis included review of single nucleotide, indel, structural, and mitochondrial variants. Results We successfully solved 218/744 (29.3%) cases using GS, with most solves involving established disease genes (157/218, 72.0%). Of all solved cases, 148 (67.9%) had previously had non-diagnostic ES. We systematically evaluated the 218 causal variants for features requiring GS to identify and 61/218 (28.0%) met these criteria, representing 8.2% of the entire cohort. These included small structural variants (13), copy neutral inversions and complex rearrangements (8), tandem repeat expansions (6), deep intronic variants (15), and coding variants that may be more easily found using GS related to uniformity of coverage (19). Conclusion We describe the diagnostic yield of GS in a large and diverse cohort, illustrating several types of pathogenic variation eluding ES or other techniques. Our results reveal a higher diagnostic yield of GS, supporting the utility of a genome-first approach, with consideration of GS as a secondary or tertiary test when higher-resolution structural variant analysis is needed or there is a strong clinical suspicion for a condition and prior targeted genetic testing has been negative.
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Amarasekera SSC, Hock DH, Lake NJ, Calvo SE, Grønborg SW, Krzesinski EI, Amor DJ, Fahey MC, Simons C, Wibrand F, Mootha VK, Lek M, Lunke S, Stark Z, Østergaard E, Christodoulou J, Thorburn DR, Stroud DA, Compton AG. Multi-omics identifies large mitoribosomal subunit instability caused by pathogenic MRPL39 variants as a cause of pediatric onset mitochondrial disease. Hum Mol Genet 2023; 32:2441-2454. [PMID: 37133451 PMCID: PMC10360397 DOI: 10.1093/hmg/ddad069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 03/20/2023] [Accepted: 04/24/2023] [Indexed: 05/04/2023] Open
Abstract
MRPL39 encodes one of 52 proteins comprising the large subunit of the mitochondrial ribosome (mitoribosome). In conjunction with 30 proteins in the small subunit, the mitoribosome synthesizes the 13 subunits of the mitochondrial oxidative phosphorylation (OXPHOS) system encoded by mitochondrial Deoxyribonucleic acid (DNA). We used multi-omics and gene matching to identify three unrelated individuals with biallelic variants in MRPL39 presenting with multisystem diseases with severity ranging from lethal, infantile-onset (Leigh syndrome spectrum) to milder with survival into adulthood. Clinical exome sequencing of known disease genes failed to diagnose these patients; however quantitative proteomics identified a specific decrease in the abundance of large but not small mitoribosomal subunits in fibroblasts from the two patients with severe phenotype. Re-analysis of exome sequencing led to the identification of candidate single heterozygous variants in mitoribosomal genes MRPL39 (both patients) and MRPL15. Genome sequencing identified a shared deep intronic MRPL39 variant predicted to generate a cryptic exon, with transcriptomics and targeted studies providing further functional evidence for causation. The patient with the milder disease was homozygous for a missense variant identified through trio exome sequencing. Our study highlights the utility of quantitative proteomics in detecting protein signatures and in characterizing gene-disease associations in exome-unsolved patients. We describe Relative Complex Abundance analysis of proteomics data, a sensitive method that can identify defects in OXPHOS disorders to a similar or greater sensitivity to the traditional enzymology. Relative Complex Abundance has potential utility for functional validation or prioritization in many hundreds of inherited rare diseases where protein complex assembly is disrupted.
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Affiliation(s)
- Sumudu S C Amarasekera
- Murdoch Children’s Research Institute, Royal Children's Hospital, Melbourne, VIC 3052, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Daniella H Hock
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC 3010, Australia
| | - Nicole J Lake
- Murdoch Children’s Research Institute, Royal Children's Hospital, Melbourne, VIC 3052, Australia
- Department of Genetics, Yale School of Medicine, New Haven, CT 06510 USA
| | - Sarah E Calvo
- Broad Institute, Cambridge, MA 02142, USA
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Systems Biology, Harvard Medical School, Boston, MA 02446, USA
| | - Sabine W Grønborg
- Department of Genetics, Copenhagen University Hospital Rigshospitalet, Copenhagen 2100, Denmark
- Center for Inherited Metabolic Disease, Department of Pediatrics and Adolescent Medicine, Copenhagen University Hospital Rigshospitalet, Copenhagen 2100, Denmark
| | - Emma I Krzesinski
- Monash Genetics, Monash Health, Melbourne, VIC 3168 Australia
- Department of Paediatrics, Monash University, Melbourne, VIC 3168 Australia
| | - David J Amor
- Murdoch Children’s Research Institute, Royal Children's Hospital, Melbourne, VIC 3052, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Michael C Fahey
- Monash Genetics, Monash Health, Melbourne, VIC 3168 Australia
- Department of Paediatrics, Monash University, Melbourne, VIC 3168 Australia
| | - Cas Simons
- Murdoch Children’s Research Institute, Royal Children's Hospital, Melbourne, VIC 3052, Australia
| | - Flemming Wibrand
- Department of Genetics, Copenhagen University Hospital Rigshospitalet, Copenhagen 2100, Denmark
| | - Vamsi K Mootha
- Broad Institute, Cambridge, MA 02142, USA
- Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Systems Biology, Harvard Medical School, Boston, MA 02446, USA
| | - Monkol Lek
- Department of Genetics, Yale School of Medicine, New Haven, CT 06510 USA
| | - Sebastian Lunke
- Victorian Clinical Genetics Services, Murdoch Children’s Research Institute, Melbourne, VIC 3052, Australia
- Australian Genomics Health Alliance, Melbourne, VIC 3052, Australia
- Department of Pathology, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Zornitza Stark
- Department of Paediatrics, University of Melbourne, Melbourne, VIC 3010, Australia
- Victorian Clinical Genetics Services, Murdoch Children’s Research Institute, Melbourne, VIC 3052, Australia
- Australian Genomics Health Alliance, Melbourne, VIC 3052, Australia
| | - Elsebet Østergaard
- Department of Genetics, Copenhagen University Hospital Rigshospitalet, Copenhagen 2100, Denmark
- Department of Clinical Medicine, University of Copenhagen, Copenhagen 2200, Denmark
| | - John Christodoulou
- Murdoch Children’s Research Institute, Royal Children's Hospital, Melbourne, VIC 3052, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, VIC 3010, Australia
- Victorian Clinical Genetics Services, Murdoch Children’s Research Institute, Melbourne, VIC 3052, Australia
- Australian Genomics Health Alliance, Melbourne, VIC 3052, Australia
- Discipline of Child & Adolescent Health, Sydney Medical School, University of Sydney, Sydney, NSW 2006, Australia
| | - David R Thorburn
- Murdoch Children’s Research Institute, Royal Children's Hospital, Melbourne, VIC 3052, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, VIC 3010, Australia
- Victorian Clinical Genetics Services, Murdoch Children’s Research Institute, Melbourne, VIC 3052, Australia
- Australian Genomics Health Alliance, Melbourne, VIC 3052, Australia
| | - David A Stroud
- Murdoch Children’s Research Institute, Royal Children's Hospital, Melbourne, VIC 3052, Australia
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC 3010, Australia
- Victorian Clinical Genetics Services, Murdoch Children’s Research Institute, Melbourne, VIC 3052, Australia
| | - Alison G Compton
- Murdoch Children’s Research Institute, Royal Children's Hospital, Melbourne, VIC 3052, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, VIC 3010, Australia
- Victorian Clinical Genetics Services, Murdoch Children’s Research Institute, Melbourne, VIC 3052, Australia
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Núñez-Moreno G, Tamayo A, Ruiz-Sánchez C, Cortón M, Mínguez P. VIsoQLR: an interactive tool for the detection, quantification and fine-tuning of isoforms in selected genes using long-read sequencing. Hum Genet 2023; 142:495-506. [PMID: 36881176 DOI: 10.1007/s00439-023-02539-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 02/23/2023] [Indexed: 03/08/2023]
Abstract
DNA variants altering the pre-mRNA splicing process represent an underestimated cause of human genetic diseases. Their association with disease traits should be confirmed using functional assays from patient cell lines or alternative models to detect aberrant mRNAs. Long-read sequencing is a suitable technique to identify and quantify mRNA isoforms. Available isoform detection and/or quantification tools are generally designed for the whole transcriptome analysis. However experiments focusing on genes of interest need more precise data fine-tuning and visualization tools.Here we describe VIsoQLR, an interactive analyzer, viewer and editor for the semi-automated identification and quantification of known and novel isoforms using long-read sequencing data. VIsoQLR is tailored to thoroughly analyze mRNA expression in splicing assays of selected genes. Our tool takes sequences aligned to a reference, and for each gene, it defines consensus splice sites and quantifies isoforms. VIsoQLR introduces features to edit the splice sites through dynamic and interactive graphics and tables, allowing accurate manual curation. Known isoforms detected by other methods can also be imported as references for comparison. A benchmark against two other popular transcriptome-based tools shows VIsoQLR accurate performance on both detection and quantification of isoforms. Here, we present VIsoQLR principles and features and its applicability in a case study example using nanopore-based long-read sequencing. VIsoQLR is available at https://github.com/TBLabFJD/VIsoQLR .
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Affiliation(s)
- Gonzalo Núñez-Moreno
- Department of Genetics and Genomics, Health Research Institute-Fundación Jiménez Díaz University Hospital, Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain.
- Bioinformatics Unit, Health Research Institute-Fundación Jiménez Díaz University Hospital, Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain.
- Center for Biomedical Network Research On Rare Diseases (CIBERER), Instituto de Salud Carlos III, Madrid, Spain.
| | - Alejandra Tamayo
- Department of Genetics and Genomics, Health Research Institute-Fundación Jiménez Díaz University Hospital, Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
- Center for Biomedical Network Research On Rare Diseases (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
- Department of Surgery, Medical and Social Sciences, Faculty of Medicine and Health Sciences, Science and Technology Campus, University of Alcalá, 28871, Alcalá de Henares, Spain
| | - Carolina Ruiz-Sánchez
- Department of Genetics and Genomics, Health Research Institute-Fundación Jiménez Díaz University Hospital, Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
| | - Marta Cortón
- Department of Genetics and Genomics, Health Research Institute-Fundación Jiménez Díaz University Hospital, Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
- Center for Biomedical Network Research On Rare Diseases (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | - Pablo Mínguez
- Department of Genetics and Genomics, Health Research Institute-Fundación Jiménez Díaz University Hospital, Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
- Bioinformatics Unit, Health Research Institute-Fundación Jiménez Díaz University Hospital, Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
- Center for Biomedical Network Research On Rare Diseases (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
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Thompson K, Stroud DA, Thorburn DR, Taylor RW. Investigation of oxidative phosphorylation activity and complex composition in mitochondrial disease. Handb Clin Neurol 2023; 194:127-139. [PMID: 36813309 DOI: 10.1016/b978-0-12-821751-1.00008-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
A multidisciplinary approach to the laboratory diagnosis of mitochondrial disease has long been applied, with crucial information provided by deep clinical phenotyping, blood investigations, and biomarker screening as well as histopathological and biochemical testing of biopsy material to support molecular genetic screening. In an era of second and third generation sequencing technologies, traditional diagnostic algorithms for mitochondrial disease have been replaced by gene agnostic, genomic strategies including whole-exome sequencing (WES) and whole-genome sequencing (WGS), increasingly supported by other 'omics technologies (Alston et al., 2021). Whether a primary testing strategy, or one used to validate and interpret candidate genetic variants, the availability of a range of tests aimed at determining mitochondrial function (i.e., the assessment of individual respiratory chain enzyme activities in a tissue biopsy or cellular respiration in a patient cell line) remains an important part of the diagnostic armory. In this chapter, we summarize several disciplines used in the laboratory investigation of suspected mitochondrial disease, including the histopathological and biochemical assessment of mitochondrial function, as well as protein-based techniques to assess the steady-state levels of oxidative phosphorylation (OXPHOS) subunits and assembly of OXPHOS complexes via traditional (immunoblotting) and cutting-edge (quantitative proteomic) approaches.
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Affiliation(s)
- Kyle Thompson
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - David A Stroud
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, VIC, Australia; Brain and Mitochondrial Research Group, Murdoch Children's Research Institute, Melbourne, VIC, Australia
| | - David R Thorburn
- Brain and Mitochondrial Research Group, Murdoch Children's Research Institute, Melbourne, VIC, Australia; Department of Paediatrics, University of Melbourne, Melbourne, VIC, Australia; Mitochondrial Laboratory, Victorian Clinical Genetic Services, Melbourne, VIC, Australia
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, United Kingdom; NHS Highly Specialised Services for Rare Mitochondrial Disorders, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom.
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Van Bergen NJ, Gunanayagam K, Bournazos AM, Walvekar AS, Warmoes MO, Semcesen LN, Lunke S, Bommireddipalli S, Sikora T, Patraskaki M, Jones DL, Garza D, Sebire D, Gooley S, McLean CA, Naidoo P, Rajasekaran M, Stroud DA, Linster CL, Wallis M, Cooper ST, Christodoulou J. Severe NAD(P)HX Dehydratase (NAXD) Neurometabolic Syndrome May Present in Adulthood after Mild Head Trauma. Int J Mol Sci 2023; 24:ijms24043582. [PMID: 36834994 PMCID: PMC9963268 DOI: 10.3390/ijms24043582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 02/01/2023] [Accepted: 02/01/2023] [Indexed: 02/12/2023] Open
Abstract
We have previously reported that pathogenic variants in a key metabolite repair enzyme NAXD cause a lethal neurodegenerative condition triggered by episodes of fever in young children. However, the clinical and genetic spectrum of NAXD deficiency is broadening as our understanding of the disease expands and as more cases are identified. Here, we report the oldest known individual succumbing to NAXD-related neurometabolic crisis, at 32 years of age. The clinical deterioration and demise of this individual were likely triggered by mild head trauma. This patient had a novel homozygous NAXD variant [NM_001242882.1:c.441+3A>G:p.?] that induces the mis-splicing of the majority of NAXD transcripts, leaving only trace levels of canonically spliced NAXD mRNA, and protein levels below the detection threshold by proteomic analysis. Accumulation of damaged NADH, the substrate of NAXD, could be detected in the fibroblasts of the patient. In agreement with prior anecdotal reports in paediatric patients, niacin-based treatment also partly alleviated some clinical symptoms in this adult patient. The present study extends our understanding of NAXD deficiency by uncovering shared mitochondrial proteomic signatures between the adult and our previously reported paediatric NAXD cases, with reduced levels of respiratory complexes I and IV as well as the mitoribosome, and the upregulation of mitochondrial apoptotic pathways. Importantly, we highlight that head trauma in adults, in addition to paediatric fever or illness, may precipitate neurometabolic crises associated with pathogenic NAXD variants.
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Affiliation(s)
- Nicole J. Van Bergen
- Brain and Mitochondrial Research Group, Murdoch Children’s Research Institute, Royal Children’s Hospital, Melbourne, VIC 3002, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, VIC 3002, Australia
- Correspondence: (N.J.V.B.); (J.C.)
| | - Karen Gunanayagam
- Department of Neurology, Royal Hobart Hospital, Hobart, TAS 7000, Australia
| | - Adam M. Bournazos
- Kids Neuroscience Centre, The Children’s Hospital at Westmead, Westmead, NSW 2145, Australia
- The Children’s Medical Research Institute, 214 Hawkesbury Road, Westmead, Sydney, NSW 2145, Australia
| | - Adhish S. Walvekar
- Enzymology and Metabolism Group, Luxembourg Centre for Systems Biomedicine, University of Luxembourg, L-4367 Belvaux, Luxembourg
| | - Marc O. Warmoes
- Enzymology and Metabolism Group, Luxembourg Centre for Systems Biomedicine, University of Luxembourg, L-4367 Belvaux, Luxembourg
| | - Liana N. Semcesen
- Department of Biochemistry & Pharmacology, Bio21 Molecular Science & Biotechnology Institute, University of Melbourne, Melbourne, VIC 3002, Australia
| | - Sebastian Lunke
- Department of Paediatrics, University of Melbourne, Melbourne, VIC 3002, Australia
- Victorian Clinical Genetics Services, Royal Children’s Hospital, Melbourne, VIC 3002, Australia
| | - Shobhana Bommireddipalli
- Kids Neuroscience Centre, The Children’s Hospital at Westmead, Westmead, NSW 2145, Australia
- The Children’s Medical Research Institute, 214 Hawkesbury Road, Westmead, Sydney, NSW 2145, Australia
| | - Tim Sikora
- Brain and Mitochondrial Research Group, Murdoch Children’s Research Institute, Royal Children’s Hospital, Melbourne, VIC 3002, Australia
| | - Myrto Patraskaki
- Enzymology and Metabolism Group, Luxembourg Centre for Systems Biomedicine, University of Luxembourg, L-4367 Belvaux, Luxembourg
| | - Dean L. Jones
- Department of Neurology, Royal Hobart Hospital, Hobart, TAS 7000, Australia
- School of Medicine, University of Tasmania, Hobart, TAS 7000, Australia
| | - Denisse Garza
- Tasmanian Clinical Genetics Service, Royal Hobart Hospital, Hobart, TAS 7000, Australia
| | - Dale Sebire
- Department of Neurology, Royal Hobart Hospital, Hobart, TAS 7000, Australia
| | - Samuel Gooley
- Department of Neurology, Royal Hobart Hospital, Hobart, TAS 7000, Australia
| | - Catriona A. McLean
- Department of Anatomical Pathology, Alfred Hospital, Melbourne, VIC 3002, Australia
| | - Parm Naidoo
- Department of Medical Imaging, Royal Hobart Hospital, Hobart, TAS 7000, Australia
| | - Mugil Rajasekaran
- Department of Medical Imaging, Royal Hobart Hospital, Hobart, TAS 7000, Australia
| | - David A. Stroud
- Brain and Mitochondrial Research Group, Murdoch Children’s Research Institute, Royal Children’s Hospital, Melbourne, VIC 3002, Australia
- Department of Biochemistry & Pharmacology, Bio21 Molecular Science & Biotechnology Institute, University of Melbourne, Melbourne, VIC 3002, Australia
| | - Carole L. Linster
- Enzymology and Metabolism Group, Luxembourg Centre for Systems Biomedicine, University of Luxembourg, L-4367 Belvaux, Luxembourg
| | - Mathew Wallis
- School of Medicine, University of Tasmania, Hobart, TAS 7000, Australia
- Tasmanian Clinical Genetics Service, Royal Hobart Hospital, Hobart, TAS 7000, Australia
| | - Sandra T. Cooper
- Kids Neuroscience Centre, The Children’s Hospital at Westmead, Westmead, NSW 2145, Australia
- The Children’s Medical Research Institute, 214 Hawkesbury Road, Westmead, Sydney, NSW 2145, Australia
- Discipline of Child and Adolescent Health, Faculty of Health and Medicine, University of Sydney, Sydney, NSW 2006, Australia
| | - John Christodoulou
- Brain and Mitochondrial Research Group, Murdoch Children’s Research Institute, Royal Children’s Hospital, Melbourne, VIC 3002, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, VIC 3002, Australia
- Victorian Clinical Genetics Services, Royal Children’s Hospital, Melbourne, VIC 3002, Australia
- Discipline of Child and Adolescent Health, Faculty of Health and Medicine, University of Sydney, Sydney, NSW 2006, Australia
- Correspondence: (N.J.V.B.); (J.C.)
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7
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Stutterd CA, Vanderver A, Lockhart PJ, Helman G, Pope K, Uebergang E, Love C, Delatycki MB, Thorburn D, Mackay MT, Peters H, Kornberg AJ, Patel C, Rodriguez-Casero V, Waak M, Silberstein J, Sinclair A, Nolan M, Field M, Davis MR, Fahey M, Scheffer IE, Freeman JL, Wolf NI, Taft RJ, van der Knaap MS, Simons C, Leventer RJ. Unclassified white matter disorders: A diagnostic journey requiring close collaboration between clinical and laboratory services. Eur J Med Genet 2022; 65:104551. [PMID: 35803560 DOI: 10.1016/j.ejmg.2022.104551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 05/27/2022] [Accepted: 06/18/2022] [Indexed: 11/26/2022]
Abstract
BACKGROUND Next generation sequencing studies have revealed an ever-increasing number of causes for genetic disorders of central nervous system white matter. A substantial number of disorders are identifiable from their specific pattern of biochemical and/or imaging findings for which single gene testing may be indicated. Beyond this group, the causes of genetic white matter disorders are unclear and a broader approach to genomic testing is recommended. AIM This study aimed to identify the genetic causes for a group of individuals with unclassified white matter disorders with suspected genetic aetiology and highlight the investigations required when the initial testing is non-diagnostic. METHODS Twenty-six individuals from 22 families with unclassified white matter disorders underwent deep phenotyping and genome sequencing performed on trio, or larger, family groups. Functional studies and transcriptomics were used to resolve variants of uncertain significance with potential clinical relevance. RESULTS Causative or candidate variants were identified in 15/22 (68.2%) families. Six of the 15 implicated genes had been previously associated with white matter disease (COL4A1, NDUFV1, SLC17A5, TUBB4A, BOLA3, DARS2). Patients with variants in the latter two presented with an atypical phenotype. The other nine genes had not been specifically associated with white matter disease at the time of diagnosis and included genes associated with monogenic syndromes, developmental disorders, and developmental and epileptic encephalopathies (STAG2, LSS, FIG4, GLS, PMPCA, SPTBN1, AGO2, SCN2A, SCN8A). Consequently, only 46% of the diagnoses would have been made via a current leukodystrophy gene panel test. DISCUSSION These results confirm the importance of broad genomic testing for patients with white matter disorders. The high diagnostic yield reflects the integration of deep phenotyping, whole genome sequencing, trio analysis, functional studies, and transcriptomic analyses. CONCLUSIONS Genetic white matter disorders are genetically and phenotypically heterogeneous. Deep phenotyping together with a range of genomic technologies underpin the identification of causes of unclassified white matter disease. A molecular diagnosis is essential for prognostication, appropriate management, and accurate reproductive counseling.
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Affiliation(s)
- C A Stutterd
- Murdoch Children's Research Institute, Victoria, Australia; Department of Neurology, Royal Children's Hospital, Victoria, Australia; Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Victoria, Australia; Department of Paediatrics, University of Melbourne, Victoria, Australia
| | - A Vanderver
- Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA; Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - P J Lockhart
- Murdoch Children's Research Institute, Victoria, Australia; Department of Paediatrics, University of Melbourne, Victoria, Australia
| | - G Helman
- Institute for Molecular Bioscience, University of Queensland, St. Lucia, Queensland, Australia
| | - K Pope
- Murdoch Children's Research Institute, Victoria, Australia
| | - E Uebergang
- Murdoch Children's Research Institute, Victoria, Australia
| | - C Love
- Murdoch Children's Research Institute, Victoria, Australia
| | - M B Delatycki
- Murdoch Children's Research Institute, Victoria, Australia; Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Victoria, Australia; Department of Paediatrics, University of Melbourne, Victoria, Australia
| | - D Thorburn
- Murdoch Children's Research Institute, Victoria, Australia; Department of Paediatrics, University of Melbourne, Victoria, Australia
| | - M T Mackay
- Murdoch Children's Research Institute, Victoria, Australia; Department of Neurology, Royal Children's Hospital, Victoria, Australia; Department of Paediatrics, University of Melbourne, Victoria, Australia
| | - H Peters
- Murdoch Children's Research Institute, Victoria, Australia; Department of Paediatrics, University of Melbourne, Victoria, Australia; Department of Metabolic Medicine, Royal Children's Hospital, Victoria, Australia
| | - A J Kornberg
- Murdoch Children's Research Institute, Victoria, Australia; Department of Neurology, Royal Children's Hospital, Victoria, Australia; Department of Paediatrics, University of Melbourne, Victoria, Australia
| | - C Patel
- Genetic Health Queensland, Royal Brisbane and Women's Children's Hospital, South Brisbane Queensland, Australia; Centre for Children's Health Research, The University of Queensland, Queensland, Australia
| | - V Rodriguez-Casero
- Murdoch Children's Research Institute, Victoria, Australia; Department of Neurology, Royal Children's Hospital, Victoria, Australia; Department of Paediatrics, University of Melbourne, Victoria, Australia
| | - M Waak
- Centre for Children's Health Research, The University of Queensland, Queensland, Australia; Department of Neurosciences, Queensland Children's Hospital, Brisbane, Queensland, Australia
| | - J Silberstein
- Princess Margaret Hospital, Perth, Western Australia, Australia
| | - A Sinclair
- Department of Neurosciences, Queensland Children's Hospital, Brisbane, Queensland, Australia
| | - M Nolan
- Department of Paediatric Neurology, Starship Children's Health, Auckland, New Zealand
| | - M Field
- Genetics of Learning Disability (GOLD) Service, Hunter Genetics, Newcastle, New South Wales, Australia
| | - M R Davis
- Department of Diagnostic Genomics, Path West Laboratory Medicine, QEII Medical Centre, Hospital Avenue, Nedlands, WA, Australia
| | - M Fahey
- Department of Paediatrics, Monash University, Victoria, Australia
| | - I E Scheffer
- Murdoch Children's Research Institute, Victoria, Australia; Department of Neurology, Royal Children's Hospital, Victoria, Australia; Department of Paediatrics, University of Melbourne, Victoria, Australia; Department of Medicine, The University of Melbourne, Austin Health, Heidelberg, Victoria, 3084, Australia; The Florey Institute of Neuroscience and Mental Health and Murdoch Children's Research Institute, Parkville, Victoria, 3052, Australia
| | - J L Freeman
- Murdoch Children's Research Institute, Victoria, Australia; Department of Neurology, Royal Children's Hospital, Victoria, Australia; Department of Paediatrics, University of Melbourne, Victoria, Australia
| | - N I Wolf
- Amsterdam Leukodystrophy Center, Department of Child Neurology, Emma Children's Hospital, Amsterdam University Medical Centers, VU University, Amsterdam Neuroscience, Amsterdam, the Netherlands; Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, VU University, Amsterdam, the Netherlands
| | - R J Taft
- Illumina Inc, San Diego, CA, USA
| | - M S van der Knaap
- Amsterdam Leukodystrophy Center, Department of Child Neurology, Emma Children's Hospital, Amsterdam University Medical Centers, VU University, Amsterdam Neuroscience, Amsterdam, the Netherlands; Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, VU University, Amsterdam, the Netherlands
| | - C Simons
- Murdoch Children's Research Institute, Victoria, Australia; Department of Paediatrics, University of Melbourne, Victoria, Australia.
| | - R J Leventer
- Murdoch Children's Research Institute, Victoria, Australia; Department of Neurology, Royal Children's Hospital, Victoria, Australia; Department of Paediatrics, University of Melbourne, Victoria, Australia.
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8
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Li Y, Liu G, Wu Z, Tu P, Wei G, Yuan M, Zhong M, Deng K, Wang F. A Novel Mitochondrial-Related Gene Signature for the Tumor Immune Microenvironment Evaluation and Prognosis Prediction in Lung Adenocarcinoma. J Immunol Res 2022; 2022:1-19. [PMID: 35664356 PMCID: PMC9159837 DOI: 10.1155/2022/5366185] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 05/01/2022] [Accepted: 05/09/2022] [Indexed: 12/14/2022] Open
Abstract
Lung adenocarcinoma (LUAD) remains the most common deadly disease and has a poor prognosis. More and more studies have reported that mitochondrial-related genes (MTRGs) were associated with the clinical outcomes of multiple tumors solely. In this study, we aimed to develop a novel prognostic model based on MTRGs. Differentially expressed MTRGs were identified from TCGA-LUAD and GSE31210 cohorts. Univariate Cox regression analysis was utilized to screen differentially expressed MTRGs that were related to prognosis of LUAD. Then, LASSO Cox regression analysis was used to develop a prognostic signature. ESTIMATE was used for estimating the fractions of immune cell types. In this study, we identified 44 overlapping differentially expressed MTRGs in TCGA-LUAD and GSE31210 cohorts. Among 44 overlapping differentially expressed MTRGs, nine genes were associated with prognosis of LUAD. When the penalty parameter lambda was the minimum, there were six genes meeting the conditions of constructing the signature, including SERPINB5, CCNB1, FGR MAOB, SH3BP5, and CYP24A1. The survival analysis suggested that prognosis of patients in the high-risk group was significantly worse than that in the low-risk group. Cox regression analyses showed that the risk score was an independent predictor of LUAD prognosis. As with the results of ESTIMATE score, the degree of immune cell infiltration in the low-risk group was higher than that in the high-risk group, such as TIL, Treg, and B cells. In addition, TMB and cancer stem cell infiltration were higher in the low-risk group than the high-risk group. In conclusion, we developed a novel MTRG signature acting as a negative independent prognostic factor. In the future, individualized treatments and medical decision-making may benefit from using the predicted model.
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9
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Keegan NP, Wilton SD, Fletcher S. Analysis of Pathogenic Pseudoexons Reveals Novel Mechanisms Driving Cryptic Splicing. Front Genet 2022; 12:806946. [PMID: 35140743 PMCID: PMC8819188 DOI: 10.3389/fgene.2021.806946] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 12/09/2021] [Indexed: 12/16/2022] Open
Abstract
Understanding pre-mRNA splicing is crucial to accurately diagnosing and treating genetic diseases. However, mutations that alter splicing can exert highly diverse effects. Of all the known types of splicing mutations, perhaps the rarest and most difficult to predict are those that activate pseudoexons, sometimes also called cryptic exons. Unlike other splicing mutations that either destroy or redirect existing splice events, pseudoexon mutations appear to create entirely new exons within introns. Since exon definition in vertebrates requires coordinated arrangements of numerous RNA motifs, one might expect that pseudoexons would only arise when rearrangements of intronic DNA create novel exons by chance. Surprisingly, although such mutations do occur, a far more common cause of pseudoexons is deep-intronic single nucleotide variants, raising the question of why these latent exon-like tracts near the mutation sites have not already been purged from the genome by the evolutionary advantage of more efficient splicing. Possible answers may lie in deep intronic splicing processes such as recursive splicing or poison exon splicing. Because these processes utilize intronic motifs that benignly engage with the spliceosome, the regions involved may be more susceptible to exonization than other intronic regions would be. We speculated that a comprehensive study of reported pseudoexons might detect alignments with known deep intronic splice sites and could also permit the characterisation of novel pseudoexon categories. In this report, we present and analyse a catalogue of over 400 published pseudoexon splice events. In addition to confirming prior observations of the most common pseudoexon mutation types, the size of this catalogue also enabled us to suggest new categories for some of the rarer types of pseudoexon mutation. By comparing our catalogue against published datasets of non-canonical splice events, we also found that 15.7% of pseudoexons exhibit some splicing activity at one or both of their splice sites in non-mutant cells. Importantly, this included seven examples of experimentally confirmed recursive splice sites, confirming for the first time a long-suspected link between these two splicing phenomena. These findings have the potential to improve the fidelity of genetic diagnostics and reveal new targets for splice-modulating therapies.
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Affiliation(s)
- Niall P. Keegan
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, WA, Australia
- Centre for Neuromuscular and Neurological Disorders, Perron Institute for Neurological and Translational Science, The University of Western Australia, Perth, WA, Australia
- *Correspondence: Niall P. Keegan,
| | - Steve D. Wilton
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, WA, Australia
- Centre for Neuromuscular and Neurological Disorders, Perron Institute for Neurological and Translational Science, The University of Western Australia, Perth, WA, Australia
| | - Sue Fletcher
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, WA, Australia
- Centre for Neuromuscular and Neurological Disorders, Perron Institute for Neurological and Translational Science, The University of Western Australia, Perth, WA, Australia
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10
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Petersen USS, Doktor TK, Andresen BS. Pseudoexon activation in disease by non-splice site deep intronic sequence variation - wild type pseudoexons constitute high-risk sites in the human genome. Hum Mutat 2021; 43:103-127. [PMID: 34837434 DOI: 10.1002/humu.24306] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Revised: 11/02/2021] [Accepted: 11/06/2021] [Indexed: 12/27/2022]
Abstract
Accuracy of pre-messenger RNA (pre-mRNA) splicing is crucial for normal gene expression. Complex regulation supports the spliceosomal distinction between authentic exons and the many seemingly functional splice sites delimiting pseudoexons. Pseudoexons are nonfunctional intronic sequences that can be activated for aberrant inclusion in mRNA, which may cause disease. Pseudoexon activation is very challenging to predict, in particular when activation occurs by sequence variants that alter the splicing regulatory environment without directly affecting splice sites. As pseudoexon inclusion often evades detection due to activation of nonsense-mediated mRNA decay, and because conventional diagnostic procedures miss deep intronic sequence variation, pseudoexon activation is a heavily underreported disease mechanism. Pseudoexon characteristics have mainly been studied based on in silico predicted sequences. Moreover, because recognition of sequence variants that create or strengthen splice sites is possible by comparison with well-established consensus sequences, this type of pseudoexon activation is by far the most frequently reported. Here we review all known human disease-associated pseudoexons that carry functional splice sites and are activated by deep intronic sequence variants located outside splice site sequences. We delineate common characteristics that make this type of wild type pseudoexons distinct high-risk sites in the human genome.
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Affiliation(s)
- Ulrika S S Petersen
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Thomas K Doktor
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Brage S Andresen
- Department of Biochemistry and Molecular Biology and the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
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11
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Cloney T, Gallacher L, Pais LS, Tan NB, Yeung A, Stark Z, Brown NJ, McGillivray G, Delatycki MB, de Silva MG, Downie L, Stutterd CA, Elliott J, Compton AG, Lovgren A, Oertel R, Francis D, Bell KM, Sadedin S, Lim SC, Helman G, Simons C, Macarthur DG, Thorburn DR, O'Donnell-Luria AH, Christodoulou J, White SM, Tan TY. Lessons learnt from multifaceted diagnostic approaches to the first 150 families in Victoria's Undiagnosed Diseases Program. J Med Genet 2021; 59:748-758. [PMID: 34740920 DOI: 10.1136/jmedgenet-2021-107902] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Accepted: 09/14/2021] [Indexed: 01/18/2023]
Abstract
BACKGROUND Clinical exome sequencing typically achieves diagnostic yields of 30%-57.5% in individuals with monogenic rare diseases. Undiagnosed diseases programmes implement strategies to improve diagnostic outcomes for these individuals. AIM We share the lessons learnt from the first 3 years of the Undiagnosed Diseases Program-Victoria, an Australian programme embedded within a clinical genetics service in the state of Victoria with a focus on paediatric rare diseases. METHODS We enrolled families who remained without a diagnosis after clinical genomic (panel, exome or genome) sequencing between 2016 and 2018. We used family-based exome sequencing (family ES), family-based genome sequencing (family GS), RNA sequencing (RNA-seq) and high-resolution chromosomal microarray (CMA) with research-based analysis. RESULTS In 150 families, we achieved a diagnosis or strong candidate in 64 (42.7%) (37 in known genes with a consistent phenotype, 3 in known genes with a novel phenotype and 24 in novel disease genes). Fifty-four diagnoses or strong candidates were made by family ES, six by family GS with RNA-seq, two by high-resolution CMA and two by data reanalysis. CONCLUSION We share our lessons learnt from the programme. Flexible implementation of multiple strategies allowed for scalability and response to the availability of new technologies. Broad implementation of family ES with research-based analysis showed promising yields post a negative clinical singleton ES. RNA-seq offered multiple benefits in family ES-negative populations. International data sharing strategies were critical in facilitating collaborations to establish novel disease-gene associations. Finally, the integrated approach of a multiskilled, multidisciplinary team was fundamental to having diverse perspectives and strategic decision-making.
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Affiliation(s)
- Thomas Cloney
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Victoria, Australia.,Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia
| | - Lyndon Gallacher
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Victoria, Australia.,Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia
| | - Lynn S Pais
- Center for Mendelian Genomics, Eli and Edythe L Broad Institute of Harvard and MIT, Cambridge, Massachusetts, USA.,Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Natalie B Tan
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Victoria, Australia.,Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia
| | - Alison Yeung
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Victoria, Australia.,Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia
| | - Zornitza Stark
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Victoria, Australia.,Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia
| | - Natasha J Brown
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Victoria, Australia.,Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia
| | - George McGillivray
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Martin B Delatycki
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Victoria, Australia.,Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia
| | - Michelle G de Silva
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Lilian Downie
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Victoria, Australia.,Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia
| | - Chloe A Stutterd
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Victoria, Australia.,Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia
| | - Justine Elliott
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Alison G Compton
- Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia.,Brain and Mitochondrial Research Group, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Alysia Lovgren
- Center for Mendelian Genomics, Eli and Edythe L Broad Institute of Harvard and MIT, Cambridge, Massachusetts, USA.,Analytic and Translational Genomics Unit, Massachusetts General Hospital, Boston, Massachusetts, USA.,Program in Medical and Population Genetics, Broad Institute, Cambridge, Massachusetts, USA
| | - Ralph Oertel
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - David Francis
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Katrina M Bell
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Victoria, Australia.,Bioinformatics, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Simon Sadedin
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Victoria, Australia.,Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia
| | - Sze Chern Lim
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Guy Helman
- Brain and Mitochondrial Research Group, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Cas Simons
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Victoria, Australia.,Translational Bioinformatics, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Daniel G Macarthur
- Center for Mendelian Genomics, Eli and Edythe L Broad Institute of Harvard and MIT, Cambridge, Massachusetts, USA.,Centre for Population Genomics, Garvan Institute of Medical Research, Sydney, New South Wales, Australia.,Centre for Population Genomics, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - David R Thorburn
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Victoria, Australia.,Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia.,Brain and Mitochondrial Research Group, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Anne H O'Donnell-Luria
- Center for Mendelian Genomics, Eli and Edythe L Broad Institute of Harvard and MIT, Cambridge, Massachusetts, USA.,Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts, USA.,Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - John Christodoulou
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Victoria, Australia.,Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia.,Neurodevelopmental Genomics Research Group, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Susan M White
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Victoria, Australia.,Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia
| | - Tiong Yang Tan
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Melbourne, Victoria, Australia .,Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia
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12
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Geldon S, Fernández-Vizarra E, Tokatlidis K. Redox-Mediated Regulation of Mitochondrial Biogenesis, Dynamics, and Respiratory Chain Assembly in Yeast and Human Cells. Front Cell Dev Biol 2021; 9:720656. [PMID: 34557489 PMCID: PMC8452992 DOI: 10.3389/fcell.2021.720656] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 08/04/2021] [Indexed: 12/24/2022] Open
Abstract
Mitochondria are double-membrane organelles that contain their own genome, the mitochondrial DNA (mtDNA), and reminiscent of its endosymbiotic origin. Mitochondria are responsible for cellular respiration via the function of the electron oxidative phosphorylation system (OXPHOS), located in the mitochondrial inner membrane and composed of the four electron transport chain (ETC) enzymes (complexes I-IV), and the ATP synthase (complex V). Even though the mtDNA encodes essential OXPHOS components, the large majority of the structural subunits and additional biogenetical factors (more than seventy proteins) are encoded in the nucleus and translated in the cytoplasm. To incorporate these proteins and the rest of the mitochondrial proteome, mitochondria have evolved varied, and sophisticated import machineries that specifically target proteins to the different compartments defined by the two membranes. The intermembrane space (IMS) contains a high number of cysteine-rich proteins, which are mostly imported via the MIA40 oxidative folding system, dependent on the reduction, and oxidation of key Cys residues. Several of these proteins are structural components or assembly factors necessary for the correct maturation and function of the ETC complexes. Interestingly, many of these proteins are involved in the metalation of the active redox centers of complex IV, the terminal oxidase of the mitochondrial ETC. Due to their function in oxygen reduction, mitochondria are the main generators of reactive oxygen species (ROS), on both sides of the inner membrane, i.e., in the matrix and the IMS. ROS generation is important due to their role as signaling molecules, but an excessive production is detrimental due to unwanted oxidation reactions that impact on the function of different types of biomolecules contained in mitochondria. Therefore, the maintenance of the redox balance in the IMS is essential for mitochondrial function. In this review, we will discuss the role that redox regulation plays in the maintenance of IMS homeostasis as well as how mitochondrial ROS generation may be a key regulatory factor for ETC biogenesis, especially for complex IV.
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Affiliation(s)
| | - Erika Fernández-Vizarra
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Kostas Tokatlidis
- Institute of Molecular Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
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13
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De Paoli-Iseppi R, Gleeson J, Clark MB. Isoform Age - Splice Isoform Profiling Using Long-Read Technologies. Front Mol Biosci 2021; 8:711733. [PMID: 34409069 PMCID: PMC8364947 DOI: 10.3389/fmolb.2021.711733] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 07/19/2021] [Indexed: 01/12/2023] Open
Abstract
Alternative splicing (AS) of RNA is a key mechanism that results in the expression of multiple transcript isoforms from single genes and leads to an increase in the complexity of both the transcriptome and proteome. Regulation of AS is critical for the correct functioning of many biological pathways, while disruption of AS can be directly pathogenic in diseases such as cancer or cause risk for complex disorders. Current short-read sequencing technologies achieve high read depth but are limited in their ability to resolve complex isoforms. In this review we examine how long-read sequencing (LRS) technologies can address this challenge by covering the entire RNA sequence in a single read and thereby distinguish isoform changes that could impact RNA regulation or protein function. Coupling LRS with technologies such as single cell sequencing, targeted sequencing and spatial transcriptomics is producing a rapidly expanding suite of technological approaches to profile alternative splicing at the isoform level with unprecedented detail. In addition, integrating LRS with genotype now allows the impact of genetic variation on isoform expression to be determined. Recent results demonstrate the potential of these techniques to elucidate the landscape of splicing, including in tissues such as the brain where AS is particularly prevalent. Finally, we also discuss how AS can impact protein function, potentially leading to novel therapeutic targets for a range of diseases.
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Affiliation(s)
| | | | - Michael B. Clark
- Centre for Stem Cell Systems, Department of Anatomy and Physiology, The University of Melbourne, Parkville, VIC, Australia
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14
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Rius R, Compton AG, Baker NL, Welch AE, Coman D, Kava MP, Minoche AE, Cowley MJ, Thorburn DR, Christodoulou J. Application of Genome Sequencing from Blood to Diagnose Mitochondrial Diseases. Genes (Basel) 2021; 12:genes12040607. [PMID: 33924034 PMCID: PMC8072654 DOI: 10.3390/genes12040607] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 04/16/2021] [Accepted: 04/17/2021] [Indexed: 12/23/2022] Open
Abstract
Mitochondrial diseases can be caused by pathogenic variants in nuclear or mitochondrial DNA-encoded genes that often lead to multisystemic symptoms and can have any mode of inheritance. Using a single test, Genome Sequencing (GS) can effectively identify variants in both genomes, but it has not yet been universally used as a first-line approach to diagnosing mitochondrial diseases due to related costs and challenges in data analysis. In this article, we report three patients with mitochondrial disease molecularly diagnosed through GS performed on DNA extracted from blood to demonstrate different diagnostic advantages of this technology, including the detection of a low-level heteroplasmic pathogenic variant, an intragenic nuclear DNA deletion, and a large mtDNA deletion. Current technical improvements and cost reductions are likely to lead to an expanded routine diagnostic usage of GS and of the complementary “Omic” technologies in mitochondrial diseases.
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Affiliation(s)
- Rocio Rius
- Murdoch Children’s Research Institute, Melbourne, VIC 3052, Australia; (R.R.); (A.G.C.); (N.L.B.) (A.E.W.); (D.R.T.)
- Department of Paediatrics, University of Melbourne, Melbourne, VIC 3052, Australia
| | - Alison G. Compton
- Murdoch Children’s Research Institute, Melbourne, VIC 3052, Australia; (R.R.); (A.G.C.); (N.L.B.) (A.E.W.); (D.R.T.)
- Department of Paediatrics, University of Melbourne, Melbourne, VIC 3052, Australia
| | - Naomi L. Baker
- Murdoch Children’s Research Institute, Melbourne, VIC 3052, Australia; (R.R.); (A.G.C.); (N.L.B.) (A.E.W.); (D.R.T.)
- Department of Paediatrics, University of Melbourne, Melbourne, VIC 3052, Australia
- Victorian Clinical Genetic Services, Melbourne, VIC 3052, Australia
| | - AnneMarie E. Welch
- Murdoch Children’s Research Institute, Melbourne, VIC 3052, Australia; (R.R.); (A.G.C.); (N.L.B.) (A.E.W.); (D.R.T.)
| | - David Coman
- Department of Metabolic Medicine, Queensland Children’s Hospital, Brisbane, QLD 4101, Australia;
- School of Clinical Medicine, University of Queensland, Brisbane, QLD 4072, Australia
- School of Medicine, Griffith University, Gold Coast, QLD 4222, Australia
| | - Maina P. Kava
- Department of Neurology, Perth Children’s Hospital, Perth, WA 6009, Australia;
- Department of Metabolic Medicine and Rheumatology, Perth Children’s Hospital, Perth, WA 6009, Australia
| | - Andre E. Minoche
- Kinghorn Centre for Clinical Genomics, Garvan Institute, University of New South Wales, Randwick, NSW 2010, Australia;
| | - Mark J. Cowley
- Precision Medicine Theme, Children’s Cancer Institute, Kensington, NSW 2750, Australia;
- School of Women’s and Children’s Health, University of New South Wales, Randwick, NSW 2031, Australia
| | - David R. Thorburn
- Murdoch Children’s Research Institute, Melbourne, VIC 3052, Australia; (R.R.); (A.G.C.); (N.L.B.) (A.E.W.); (D.R.T.)
- Department of Paediatrics, University of Melbourne, Melbourne, VIC 3052, Australia
- Victorian Clinical Genetic Services, Melbourne, VIC 3052, Australia
| | - John Christodoulou
- Murdoch Children’s Research Institute, Melbourne, VIC 3052, Australia; (R.R.); (A.G.C.); (N.L.B.) (A.E.W.); (D.R.T.)
- Department of Paediatrics, University of Melbourne, Melbourne, VIC 3052, Australia
- Victorian Clinical Genetic Services, Melbourne, VIC 3052, Australia
- Correspondence: ; Tel.: +61-39936-6353
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15
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Alston CL, Stenton SL, Hudson G, Prokisch H, Taylor RW. The genetics of mitochondrial disease: dissecting mitochondrial pathology using multi-omic pipelines. J Pathol 2021; 254:430-442. [PMID: 33586140 PMCID: PMC8600955 DOI: 10.1002/path.5641] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 02/07/2021] [Accepted: 02/09/2021] [Indexed: 12/12/2022]
Abstract
Mitochondria play essential roles in numerous metabolic pathways including the synthesis of adenosine triphosphate through oxidative phosphorylation. Clinically, mitochondrial diseases occur when there is mitochondrial dysfunction – manifesting at any age and affecting any organ system; tissues with high energy requirements, such as muscle and the brain, are often affected. The clinical heterogeneity is parallel to the degree of genetic heterogeneity associated with mitochondrial dysfunction. Around 10% of human genes are predicted to have a mitochondrial function, and defects in over 300 genes are reported to cause mitochondrial disease. Some involve the mitochondrial genome (mtDNA), but the vast majority occur within the nuclear genome. Except for a few specific genetic defects, there remains no cure for mitochondrial diseases, which means that a genetic diagnosis is imperative for genetic counselling and the provision of reproductive options for at‐risk families. Next‐generation sequencing strategies, particularly exome and whole‐genome sequencing, have revolutionised mitochondrial diagnostics such that the traditional muscle biopsy has largely been replaced with a minimally‐invasive blood sample for an unbiased approach to genetic diagnosis. Where these genomic approaches have not identified a causative defect, or where there is insufficient support for pathogenicity, additional functional investigations are required. The application of supplementary ‘omics’ technologies, including transcriptomics, proteomics, and metabolomics, has the potential to greatly improve diagnostic strategies. This review aims to demonstrate that whilst a molecular diagnosis can be achieved for many cases through next‐generation sequencing of blood DNA, the use of patient tissues and an integrated, multidisciplinary multi‐omics approach is pivotal for the diagnosis of more challenging cases. Moreover, the analysis of clinically relevant tissues from affected individuals remains crucial for understanding the molecular mechanisms underlying mitochondrial pathology. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.
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Affiliation(s)
- Charlotte L Alston
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.,NHS Highly Specialised Services for Rare Mitochondrial Disorders, Royal Victoria Infirmary, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Sarah L Stenton
- Institute of Human Genetics, Technische Universität München, München, Germany.,Institute of Neurogenomics, Helmholtz Zentrum München, Neuherberg, Germany
| | - Gavin Hudson
- Wellcome Centre for Mitochondrial Research, Bioscience Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Holger Prokisch
- Institute of Human Genetics, Technische Universität München, München, Germany.,Institute of Neurogenomics, Helmholtz Zentrum München, Neuherberg, Germany
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.,NHS Highly Specialised Services for Rare Mitochondrial Disorders, Royal Victoria Infirmary, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
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