1
|
Krenn M, Wagner M, Zulehner G, Weng R, Jäger F, Keritam O, Sener M, Brücke C, Milenkovic I, Langer A, Buchinger D, Habersam R, Mayerhanser K, Brugger M, Brunet T, Jacob M, Graf E, Berutti R, Cetin H, Hoefele J, Winkelmann J, Zimprich F, Rath J. Next-generation sequencing and comprehensive data reassessment in 263 adult patients with neuromuscular disorders: insights into the gray zone of molecular diagnoses. J Neurol 2024; 271:1937-1946. [PMID: 38127101 PMCID: PMC10972933 DOI: 10.1007/s00415-023-12101-6] [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: 09/20/2023] [Revised: 11/03/2023] [Accepted: 11/04/2023] [Indexed: 12/23/2023]
Abstract
BACKGROUND Neuromuscular disorders (NMDs) are heterogeneous conditions with a considerable fraction attributed to monogenic defects. Despite the advancements in genomic medicine, many patients remain without a diagnosis. Here, we investigate whether a comprehensive reassessment strategy improves the diagnostic outcomes. METHODS We analyzed 263 patients with NMD phenotypes that underwent diagnostic exome or genome sequencing at our tertiary referral center between 2015 and 2023. We applied a comprehensive reassessment encompassing variant reclassification, re-phenotyping and NGS data reanalysis. Multivariable logistic regression was performed to identify predictive factors associated with a molecular diagnosis. RESULTS Initially, a molecular diagnosis was identified in 53 cases (20%), while an additional 23 (9%) had findings of uncertain significance. Following comprehensive reassessment, the diagnostic yield increased to 23%, revealing 44 distinct monogenic etiologies. Reasons for newly obtained molecular diagnoses were variant reclassifications in 7 and NGS data reanalysis in 3 cases including one recently described disease-gene association (DNAJB4). Male sex reduced the odds of receiving a molecular diagnosis (OR 0.42; 95%CI 0.21-0.82), while a positive family history (OR 5.46; 95%CI 2.60-11.76) and a myopathy phenotype (OR 2.72; 95%CI 1.11-7.14) increased the likelihood. 7% were resolved through targeted genetic testing or classified as acquired etiologies. CONCLUSION Our findings reinforce the use of NGS in NMDs of suspected monogenic origin. We show that a comprehensive reassessment enhances diagnostic accuracy. However, one needs to be aware that genetic diagnoses are often made with uncertainty and can even be downgraded based on new evidence.
Collapse
Affiliation(s)
- Martin Krenn
- Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
- Comprehensive Center for Clinical Neurosciences and Mental Health, Medical University of Vienna, Vienna, Austria
| | - Matias Wagner
- Institute of Human Genetics, Klinikum Rechts Der Isar, School of Medicine, Technical University of Munich, Munich, Germany
- Institute of Neurogenomics, Helmholtz Zentrum München, Munich, Germany
| | - Gudrun Zulehner
- Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
- Comprehensive Center for Clinical Neurosciences and Mental Health, Medical University of Vienna, Vienna, Austria
| | - Rosa Weng
- Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
- Comprehensive Center for Clinical Neurosciences and Mental Health, Medical University of Vienna, Vienna, Austria
| | - Fiona Jäger
- Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
- Comprehensive Center for Clinical Neurosciences and Mental Health, Medical University of Vienna, Vienna, Austria
| | - Omar Keritam
- Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
- Comprehensive Center for Clinical Neurosciences and Mental Health, Medical University of Vienna, Vienna, Austria
| | - Merve Sener
- Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
- Comprehensive Center for Clinical Neurosciences and Mental Health, Medical University of Vienna, Vienna, Austria
| | - Christof Brücke
- Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
- Comprehensive Center for Clinical Neurosciences and Mental Health, Medical University of Vienna, Vienna, Austria
| | - Ivan Milenkovic
- Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
- Comprehensive Center for Clinical Neurosciences and Mental Health, Medical University of Vienna, Vienna, Austria
| | - Agnes Langer
- Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
- Comprehensive Center for Clinical Neurosciences and Mental Health, Medical University of Vienna, Vienna, Austria
| | - Dominic Buchinger
- Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
- Comprehensive Center for Clinical Neurosciences and Mental Health, Medical University of Vienna, Vienna, Austria
| | - Richard Habersam
- Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
- Comprehensive Center for Clinical Neurosciences and Mental Health, Medical University of Vienna, Vienna, Austria
| | - Katharina Mayerhanser
- Institute of Human Genetics, Klinikum Rechts Der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Melanie Brugger
- Institute of Human Genetics, Klinikum Rechts Der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Theresa Brunet
- Institute of Human Genetics, Klinikum Rechts Der Isar, School of Medicine, Technical University of Munich, Munich, Germany
- Department of Pediatric Neurology, Developmental Medicine and Social Pediatrics, Dr. Von Hauner's Children's Hospital, University of Munich, Munich, Germany
| | - Maureen Jacob
- Institute of Human Genetics, Klinikum Rechts Der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Elisabeth Graf
- Institute of Human Genetics, Klinikum Rechts Der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Riccardo Berutti
- Institute of Human Genetics, Klinikum Rechts Der Isar, School of Medicine, Technical University of Munich, Munich, Germany
- Institute of Neurogenomics, Helmholtz Zentrum München, Munich, Germany
| | - Hakan Cetin
- Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
- Comprehensive Center for Clinical Neurosciences and Mental Health, Medical University of Vienna, Vienna, Austria
| | - Julia Hoefele
- Institute of Human Genetics, Klinikum Rechts Der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Juliane Winkelmann
- Institute of Human Genetics, Klinikum Rechts Der Isar, School of Medicine, Technical University of Munich, Munich, Germany
- Institute of Neurogenomics, Helmholtz Zentrum München, Munich, Germany
| | - Fritz Zimprich
- Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
- Comprehensive Center for Clinical Neurosciences and Mental Health, Medical University of Vienna, Vienna, Austria
| | - Jakob Rath
- Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria.
- Comprehensive Center for Clinical Neurosciences and Mental Health, Medical University of Vienna, Vienna, Austria.
| |
Collapse
|
2
|
Weston TGR, Rees M, Gautel M, Fraternali F. Walking with giants: The challenges of variant impact assessment in the giant sarcomeric protein titin. WIREs Mech Dis 2024; 16:e1638. [PMID: 38155593 DOI: 10.1002/wsbm.1638] [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: 06/15/2023] [Revised: 12/01/2023] [Accepted: 12/04/2023] [Indexed: 12/30/2023]
Abstract
Titin, the so-called "third filament" of the sarcomere, represents a difficult challenge for the determination of damaging genetic variants. A single titin molecule extends across half the length of a sarcomere in striated muscle, fulfilling a variety of vital structural and signaling roles, and has been linked to an equally varied range of myopathies, resulting in a significant burden on individuals and healthcare systems alike. While the consequences of truncating variants of titin are well-documented, the ramifications of the missense variants prevalent in the general population are less so. We here present a compendium of titin missense variants-those that result in a single amino-acid substitution in coding regions-reported to be pathogenic and discuss these in light of the nature of titin and the variant position within the sarcomere and their domain, the structural, pathological, and biophysical characteristics that define them, and the methods used for characterization. Finally, we discuss the current knowledge and integration of the multiple fields that have contributed to our understanding of titin-related pathology and offer suggestions as to how these concurrent methodologies may aid the further development in our understanding of titin and hopefully extend to other, less well-studied giant proteins. This article is categorized under: Cardiovascular Diseases > Genetics/Genomics/Epigenetics Congenital Diseases > Genetics/Genomics/Epigenetics Congenital Diseases > Molecular and Cellular Physiology.
Collapse
Affiliation(s)
- Timir G R Weston
- Randall Centre for Cell & Molecular Biophysics, King's College London, London, UK
| | - Martin Rees
- Randall Centre for Cell & Molecular Biophysics, King's College London, London, UK
| | - Mathias Gautel
- Randall Centre for Cell & Molecular Biophysics, King's College London, London, UK
| | - Franca Fraternali
- Institute of Structural and Molecular Biology, University College London, London, UK
| |
Collapse
|
3
|
Rees M, Nikoopour R, Alexandrovich A, Pfuhl M, Lopes LR, Akhtar MM, Syrris P, Elliott P, Carr-White G, Gautel M. Structure determination and analysis of titin A-band fibronectin type III domains provides insights for disease-linked variants and protein oligomerisation. J Struct Biol 2023; 215:108009. [PMID: 37549721 PMCID: PMC10862085 DOI: 10.1016/j.jsb.2023.108009] [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: 04/30/2023] [Revised: 07/06/2023] [Accepted: 08/03/2023] [Indexed: 08/09/2023]
Abstract
Titin is the largest protein found in nature and spans half a sarcomere in vertebrate striated muscle. The protein has multiple functions, including in the organisation of the thick filament and acting as a molecular spring during the muscle contraction cycle. Missense variants in titin have been linked to both cardiac and skeletal myopathies. Titin is primarily composed of tandem repeats of immunoglobulin and fibronectin type III (Fn3) domains in a variety of repeat patterns; however, the vast majority of these domains have not had their high-resolution structure determined experimentally. Here, we present the crystal structures of seven wild type titin Fn3 domains and two harbouring rare missense variants reported in hypertrophic cardiomyopathy (HCM) patients. All domains present the typical Fn3 fold, with the domains harbouring variants reported in HCM patients retaining the wild-type conformation. The effect on domain folding and stability were assessed for five rare missense variants found in HCM patients: four caused thermal destabilization of between 7 and 13 °C and one prevented the folding of its domain. The structures also allowed us to locate the positions of residues whose mutations have been linked to congenital myopathies and rationalise how they convey their deleterious effects. We find no evidence of physiological homodimer formation, excluding one hypothesised mechanism as to how titin variants could exert pathological effects.
Collapse
Affiliation(s)
- Martin Rees
- Randall Centre for Cell and Molecular Biophysics, King's College London BHF Centre of Research Excellence, United Kingdom.
| | - Roksana Nikoopour
- Randall Centre for Cell and Molecular Biophysics, King's College London BHF Centre of Research Excellence, United Kingdom
| | - Alexander Alexandrovich
- Randall Centre for Cell and Molecular Biophysics, King's College London BHF Centre of Research Excellence, United Kingdom
| | - Mark Pfuhl
- Randall Centre for Cell and Molecular Biophysics, King's College London BHF Centre of Research Excellence, United Kingdom; School of Cardiovascular Sciences and Medicine, King's College London, United Kingdom
| | - Luis R Lopes
- Institute of Cardiovascular Science, University College London, United Kingdom; Barts Heart Centre, St Bartholomew's Hospital, London, United Kingdom
| | - Mohammed M Akhtar
- Institute of Cardiovascular Science, University College London, United Kingdom
| | - Petros Syrris
- Institute of Cardiovascular Science, University College London, United Kingdom
| | - Perry Elliott
- Institute of Cardiovascular Science, University College London, United Kingdom; Barts Heart Centre, St Bartholomew's Hospital, London, United Kingdom
| | - Gerry Carr-White
- Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom; School of Biomedical Engineering and Imaging Sciences, Rayne Institute, King's College London, St Thomas' Hospital, London, United Kingdom
| | - Mathias Gautel
- Randall Centre for Cell and Molecular Biophysics, King's College London BHF Centre of Research Excellence, United Kingdom.
| |
Collapse
|
4
|
Mauriello GE, Moncure GE, Nowzari RA, Miller CJ, Wright NT. The N-terminus of obscurin is flexible in solution. Proteins 2023; 91:485-496. [PMID: 36306263 DOI: 10.1002/prot.26442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 10/13/2022] [Accepted: 10/21/2022] [Indexed: 11/06/2022]
Abstract
The N-terminal half of the giant cytoskeletal protein obscurin is comprised of more than 50 Ig-like domains, arranged in tandem. Domains 18-51 are connected to each other through short 5-residue linkers, and this arrangement has been previously shown to form a semi-flexible rod in solution. Domains 1-18 generally have slightly longer ~7 residue interdomain linkers, and the multidomain structure and motion conferred by this kind of linker is understudied. Here, we use NMR, SAXS, and MD to show that these longer linkers are associated with significantly more domain/domain flexibility, with the resulting multidomain structure being moderately compact. Further examination of the relationship between interdomain flexibility and linker length shows there is a 5 residue "sweet spot" linker length that results in dual-domain systems being extended, and conversely that both longer or shorter linkers result in a less extended structure. This detailed knowledge of the obscurin N terminus structure and flexibility allowed for mathematical modeling of domains 1-18, which suggests that this region likely forms tangles if left alone in solution. Given how infrequently protein tangles occur in nature, and given the pathological outcomes that occur when tangles do arise, our data suggest that obscurin is likely either significantly scaffolded or else externally extended in the cell.
Collapse
Affiliation(s)
- Gianna E Mauriello
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, USA
| | - Grace E Moncure
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, USA
| | - Roujon A Nowzari
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, USA
| | - Callie J Miller
- Department of Engineering, James Madison University, Harrisonburg, Virginia, USA
| | - Nathan T Wright
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, USA
| |
Collapse
|
5
|
Rees M, Nikoopour R, Fukuzawa A, Kho AL, Fernandez-Garcia MA, Wraige E, Bodi I, Deshpande C, Özdemir Ö, Daimagüler HS, Pfuhl M, Holt M, Brandmeier B, Grover S, Fluss J, Longman C, Farrugia ME, Matthews E, Hanna M, Muntoni F, Sarkozy A, Phadke R, Quinlivan R, Oates EC, Schröder R, Thiel C, Reimann J, Voermans N, Erasmus C, Kamsteeg EJ, Konersman C, Grosmann C, McKee S, Tirupathi S, Moore SA, Wilichowski E, Hobbiebrunken E, Dekomien G, Richard I, Van den Bergh P, Domínguez-González C, Cirak S, Ferreiro A, Jungbluth H, Gautel M. Making sense of missense variants in TTN-related congenital myopathies. Acta Neuropathol 2021; 141:431-453. [PMID: 33449170 PMCID: PMC7882473 DOI: 10.1007/s00401-020-02257-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 12/20/2020] [Accepted: 12/20/2020] [Indexed: 12/15/2022]
Abstract
Mutations in the sarcomeric protein titin, encoded by TTN, are emerging as a common cause of myopathies. The diagnosis of a TTN-related myopathy is, however, often not straightforward due to clinico-pathological overlap with other myopathies and the prevalence of TTN variants in control populations. Here, we present a combined clinico-pathological, genetic and biophysical approach to the diagnosis of TTN-related myopathies and the pathogenicity ascertainment of TTN missense variants. We identified 30 patients with a primary TTN-related congenital myopathy (CM) and two truncating variants, or one truncating and one missense TTN variant, or homozygous for one TTN missense variant. We found that TTN-related myopathies show considerable overlap with other myopathies but are strongly suggested by a combination of certain clinico-pathological features. Presentation was typically at birth with the clinical course characterized by variable progression of weakness, contractures, scoliosis and respiratory symptoms but sparing of extraocular muscles. Cardiac involvement depended on the variant position. Our biophysical analyses demonstrated that missense mutations associated with CMs are strongly destabilizing and exert their effect when expressed on a truncating background or in homozygosity. We hypothesise that destabilizing TTN missense mutations phenocopy truncating variants and are a key pathogenic feature of recessive titinopathies that might be amenable to therapeutic intervention.
Collapse
Affiliation(s)
- Martin Rees
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
| | - Roksana Nikoopour
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
| | - Atsushi Fukuzawa
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
| | - Ay Lin Kho
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
| | - Miguel A Fernandez-Garcia
- Department of Paediatric Neurology, Evelina Children's Hospital, Guy's & St Thomas' NHS Foundation Trust, London, UK
| | - Elizabeth Wraige
- Department of Paediatric Neurology, Evelina Children's Hospital, Guy's & St Thomas' NHS Foundation Trust, London, UK
| | - Istvan Bodi
- Department of Clinical Neuropathology, King's College Hospital, London, UK
| | | | - Özkan Özdemir
- Centre for Molecular Medicine, University of Cologne, Cologne, Germany
- Department of Pediatrics, University Hospital Cologne and Faculty of Medicine, University of Cologne, Cologne, Germany
| | - Hülya-Sevcan Daimagüler
- Centre for Molecular Medicine, University of Cologne, Cologne, Germany
- Department of Pediatrics, University Hospital Cologne and Faculty of Medicine, University of Cologne, Cologne, Germany
| | - Mark Pfuhl
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
- School of Cardiovascular Medicine and Sciences, King's College London BHF Centre of Research Excellence, London, UK
| | - Mark Holt
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
- School of Cardiovascular Medicine and Sciences, King's College London BHF Centre of Research Excellence, London, UK
| | - Birgit Brandmeier
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
| | - Sarah Grover
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
| | - Joël Fluss
- Pediatric Neurology Unit, Paediatrics Subspecialties Service, Geneva Children's Hospital, Geneva, Switzerland
| | - Cheryl Longman
- West of Scotland Regional Genetics Service, Laboratory Medicine Building, Queen Elizabeth University Hospital, Glasgow, UK
| | | | - Emma Matthews
- MRC Neuromuscular Centre, National Hospital for Neurology and Neurosurgery, Queen's Square, London, UK
| | - Michael Hanna
- MRC Neuromuscular Centre, National Hospital for Neurology and Neurosurgery, Queen's Square, London, UK
| | - Francesco Muntoni
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital for Children, London, UK
- NIHR Great Ormond Street Hospital Biomedical Research Centre, Great Ormond Street Institute of Child Health, University College London, Great Ormond Street Hospital Trust, London, UK
| | - Anna Sarkozy
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital for Children, London, UK
| | - Rahul Phadke
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital for Children, London, UK
| | - Ros Quinlivan
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital for Children, London, UK
| | - Emily C Oates
- Dubowitz Neuromuscular Centre, Great Ormond Street Hospital for Children, London, UK
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sidney, Australia
- Kids Neuroscience Centre, Kids Research, The Children's Hospital at Westmead, Sydney, NSW, Australia
| | - Rolf Schröder
- Institute of Neuropathology, University Hospital Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Christian Thiel
- Department of Genetics, University of Erlangen, Erlangen, Germany
| | - Jens Reimann
- Muscle Laboratory, Department of Neurology, University of Bonn Medical Centre, Bonn, Germany
| | - Nicol Voermans
- Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
| | - Corrie Erasmus
- Department of Paediatric Neurology, Radboud University, Nijmegen, The Netherlands
| | - Erik-Jan Kamsteeg
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Chaminda Konersman
- UCSD, Rady Children's Hospital, and VA San Diego Healthcare System, San Diego, USA
| | | | - Shane McKee
- Northern Ireland Regional Genetics Service, Belfast City Hospital, Belfast, UK
| | - Sandya Tirupathi
- Department of Paediatric Neurology, Royal Belfast Hospital for Sick Children, Belfast, UK
| | - Steven A Moore
- Department of Pathology, The University of Iowa, Iowa City, IA, USA
| | | | - Elke Hobbiebrunken
- Department of Paediatric Neurology, University of Göttingen, Göttingen, Germany
| | | | - Isabelle Richard
- Genethon and UMR_S951, INSERM, Université Evry, Université Paris Saclay, Evry, 91002, Evry, France
| | - Peter Van den Bergh
- Neuromuscular Reference Centre, Department of Neurology, University Hospital Saint-Luc, Brussels, Belgium
| | | | - Sebahattin Cirak
- Centre for Molecular Medicine, University of Cologne, Cologne, Germany
- Department of Pediatrics, University Hospital Cologne and Faculty of Medicine, University of Cologne, Cologne, Germany
- Centre for Rare Diseases (ZSEK), University of Cologne, Cologne, Germany
| | - Ana Ferreiro
- Basic and Translational Myology Laboratory, Université de Paris, Paris, France
- Centre de Référence Des Maladies Neuromusculaires, APHP, Institut of Myology, GHU Pitié Salpêtrière- Charles Foix, Paris, France
| | - Heinz Jungbluth
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK
- Department of Paediatric Neurology, Evelina Children's Hospital, Guy's & St Thomas' NHS Foundation Trust, London, UK
- Department of Clinical and Basic Neuroscience, IoPPN, King's College London, London, UK
| | - Mathias Gautel
- Randall Centre for Cell and Molecular Biophysics, Muscle Biophysics, King's College London BHF Centre of Research Excellence, London, UK.
| |
Collapse
|
6
|
Fukuzawa A, Koch D, Grover S, Rees M, Gautel M. When is an obscurin variant pathogenic? The impact of Arg4344Gln and Arg4444Trp variants on protein-protein interactions and protein stability. Hum Mol Genet 2021; 30:1131-1141. [PMID: 33438037 PMCID: PMC8188405 DOI: 10.1093/hmg/ddab010] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 12/17/2020] [Accepted: 01/04/2021] [Indexed: 11/13/2022] Open
Abstract
Obscurin is a giant muscle protein that connects the sarcomere with the sarcoplasmic reticulum, and has poorly understood structural and signalling functions. Increasingly, obscurin variants are implicated in the pathophysiology of cardiovascular diseases. The Arg4344Gln variant (R4344Q) in obscurin domain Ig58, initially discovered in a patient with hypertrophic cardiomyopathy, has been reported to reduce binding to titin domains Z8-Z9, impairing obscurin’s Z-disc localization. An R4344Q knock-in mouse developed a cardiomyopathy-like phenotype with abnormal Ca2+-handling and arrhythmias, which were attributed to an enhanced affinity of a putative interaction between obscurin Ig58 and phospholamban (PLN) due to the R4344Q variant. However, the R4344Q variant is found in 15% of African Americans, arguing against its pathogenicity. To resolve this apparent paradox, we quantified the influence of the R4344Q variant (alongside another potentially pathogenic variant: Arg4444Trp (R4444W)) on binding to titin Z8-Z9, novex-3 and PLN using pull-down assays and microscale thermophoresis and characterized the influence on domain stability using differential scanning fluorimetry. We found no changes in titin binding and thermostability for both variants and modestly increased affinities of PLN for R4344Q and R4444W. While we could not confirm the novex-3/obscurin interaction, the PLN/obscurin interaction relies on the transmembrane region of PLN and is not reproducible in mammalian cells, suggesting it is an in vitro artefact. Without clear clinical evidence for disease involvement, we advise against classifying these obscurin variants as pathogenic.
Collapse
Affiliation(s)
- Atsushi Fukuzawa
- Randall Centre for Cell & Molecular Biophysics, King's College London, 18-20 Newcomen Street, SE1 1UL, UK
| | - Daniel Koch
- Randall Centre for Cell & Molecular Biophysics, King's College London, 18-20 Newcomen Street, SE1 1UL, UK
| | - Sarah Grover
- Randall Centre for Cell & Molecular Biophysics, King's College London, 18-20 Newcomen Street, SE1 1UL, UK
| | - Martin Rees
- Randall Centre for Cell & Molecular Biophysics, King's College London, 18-20 Newcomen Street, SE1 1UL, UK
| | - Mathias Gautel
- Randall Centre for Cell & Molecular Biophysics, King's College London, 18-20 Newcomen Street, SE1 1UL, UK
| |
Collapse
|
7
|
Chatziefthimiou SD, Hornburg P, Sauer F, Mueller S, Ugurlar D, Xu ER, Wilmanns M. Structural diversity in the atomic resolution 3D fingerprint of the titin M-band segment. PLoS One 2019; 14:e0226693. [PMID: 31856237 PMCID: PMC6922384 DOI: 10.1371/journal.pone.0226693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 12/02/2019] [Indexed: 11/18/2022] Open
Abstract
In striated muscles, molecular filaments are largely composed of long protein chains with extensive arrays of identically folded domains, referred to as “beads-on-a-string”. It remains a largely unresolved question how these domains have developed a unique molecular profile such that each carries out a distinct function without false-positive readout. This study focuses on the M-band segment of the sarcomeric protein titin, which comprises ten identically folded immunoglobulin domains. Comparative analysis of high-resolution structures of six of these domains ‒ M1, M3, M4, M5, M7, and M10 ‒ reveals considerable structural diversity within three distinct loops and a non-conserved pattern of exposed cysteines. Our data allow to structurally interpreting distinct pathological readouts that result from titinopathy-associated variants. Our findings support general principles that could be used to identify individual structural/functional profiles of hundreds of identically folded protein domains within the sarcomere and other densely crowded cellular environments.
Collapse
Affiliation(s)
| | - Philipp Hornburg
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Florian Sauer
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Simone Mueller
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Deniz Ugurlar
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Emma-Ruoqi Xu
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Matthias Wilmanns
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
- University Hamburg Medical Centre Hamburg-Eppendorf, Hamburg, Germany
- * E-mail:
| |
Collapse
|
8
|
Ng R, Manring H, Papoutsidakis N, Albertelli T, Tsai N, See CJ, Li X, Park J, Stevens TL, Bobbili PJ, Riaz M, Ren Y, Stoddard CE, Janssen PM, Bunch TJ, Hall SP, Lo YC, Jacoby DL, Qyang Y, Wright N, Ackermann MA, Campbell SG. Patient mutations linked to arrhythmogenic cardiomyopathy enhance calpain-mediated desmoplakin degradation. JCI Insight 2019; 5:128643. [PMID: 31194698 DOI: 10.1172/jci.insight.128643] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Arrhythmogenic cardiomyopathy (ACM) is an inherited disorder with variable genetic etiologies. Here we focused on understanding the precise molecular pathology of a single clinical variant in DSP, the gene encoding desmoplakin. We initially identified a novel missense desmoplakin variant (p.R451G) in a patient diagnosed with biventricular ACM. An extensive single-family ACM cohort was assembled, revealing a pattern of coinheritance for R451G desmoplakin and the ACM phenotype. An in vitro model system using patient-derived induced pluripotent stem cell lines showed depressed levels of desmoplakin in the absence of abnormal electrical propagation. Molecular dynamics simulations of desmoplakin R451G revealed no overt structural changes, but a significant loss of intramolecular interactions surrounding a putative calpain target site was observed. Protein degradation assays of recombinant desmoplakin R451G confirmed increased calpain vulnerability. In silico screening identified a subset of 3 additional ACM-linked desmoplakin missense mutations with apparent enhanced calpain susceptibility, predictions that were confirmed experimentally. Like R451G, these mutations are found in families with biventricular ACM. We conclude that augmented calpain-mediated degradation of desmoplakin represents a shared pathological mechanism for select ACM-linked missense variants. This approach for identifying variants with shared molecular pathologies may represent a powerful new strategy for understanding and treating inherited cardiomyopathies.
Collapse
Affiliation(s)
- Ronald Ng
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, USA
| | - Heather Manring
- Department of Physiology and Cell Biology and.,Dorothy M. Davis Heart and Lung Research Institute, Wexner Medical Center, The Ohio State University, Columbus, Ohio, USA
| | - Nikolaos Papoutsidakis
- Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut, USA
| | - Taylor Albertelli
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, USA
| | - Nicole Tsai
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut, USA
| | - Claudia J See
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, USA
| | - Xia Li
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, USA.,Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut, USA
| | - Jinkyu Park
- Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut, USA
| | - Tyler L Stevens
- Department of Physiology and Cell Biology and.,Dorothy M. Davis Heart and Lung Research Institute, Wexner Medical Center, The Ohio State University, Columbus, Ohio, USA
| | - Prameela J Bobbili
- Department of Physiology and Cell Biology and.,Dorothy M. Davis Heart and Lung Research Institute, Wexner Medical Center, The Ohio State University, Columbus, Ohio, USA
| | - Muhammad Riaz
- Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut, USA
| | - Yongming Ren
- Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut, USA
| | - Christopher E Stoddard
- Department of Genetics and Genome Science, University of Connecticut Health, Farmington, Connecticut, USA
| | | | - T Jared Bunch
- Department of Cardiology, Intermountain Health, Salt Lake City, Utah, USA
| | - Stephen P Hall
- Department of Family Medicine, University of Washington School of Medicine, Seattle, Washington, USA
| | - Ying-Chun Lo
- Department of Pathology, Yale School of Medicine, New Haven, Connecticut, USA
| | - Daniel L Jacoby
- Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut, USA
| | - Yibing Qyang
- Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut, USA.,Department of Pathology, Yale School of Medicine, New Haven, Connecticut, USA.,Yale Stem Cell Center, Yale University, New Haven, Connecticut, USA.,Vascular Biology and Therapeutics Program and
| | - Nathan Wright
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, USA
| | - Maegen A Ackermann
- Department of Physiology and Cell Biology and.,Dorothy M. Davis Heart and Lung Research Institute, Wexner Medical Center, The Ohio State University, Columbus, Ohio, USA
| | - Stuart G Campbell
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, USA.,Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut, USA
| |
Collapse
|
9
|
Murphy S, Dowling P, Zweyer M, Swandulla D, Ohlendieck K. Proteomic profiling of giant skeletal muscle proteins. Expert Rev Proteomics 2019; 16:241-256. [DOI: 10.1080/14789450.2019.1575205] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Sandra Murphy
- Department of Biology, Maynooth University, National University of Ireland, Maynooth, Ireland
- Newcastle Fibrosis Research Group, Institute of Cellular Medicine, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Paul Dowling
- Department of Biology, Maynooth University, National University of Ireland, Maynooth, Ireland
| | - Margit Zweyer
- Institute of Physiology II, University of Bonn, Bonn, Germany
| | | | - Kay Ohlendieck
- Department of Biology, Maynooth University, National University of Ireland, Maynooth, Ireland
| |
Collapse
|
10
|
Whitley JA, Ex-Willey AM, Marzolf DR, Ackermann MA, Tongen AL, Kokhan O, Wright NT. Obscurin is a semi-flexible molecule in solution. Protein Sci 2019; 28:717-726. [PMID: 30666746 DOI: 10.1002/pro.3578] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 01/14/2019] [Indexed: 01/10/2023]
Abstract
Obscurin, a giant modular cytoskeletal protein, is comprised mostly of tandem immunoglobulin-like (Ig-like) domains. This architecture allows obscurin to connect distal targets within the cell. The linkers connecting the Ig domains are usually short (3-4 residues). The physical effect arising from these short linkers is not known; such linkers may lead to a stiff elongated molecule or, conversely, may lead to a more compact and dynamic structure. In an effort to better understand how linkers affect obscurin flexibility, and to better understand the physical underpinnings of this flexibility, here we study the structure and dynamics of four representative sets of dual obscurin Ig domains using experimental and computational techniques. We find in all cases tested that tandem obscurin Ig domains interact at the poles of each domain and tend to stay relatively extended in solution. NMR, SAXS, and MD simulations reveal that while tandem domains are elongated, they also bend and flex significantly. By applying this behavior to a simplified model, it becomes apparent obscurin can link targets more than 200 nm away. However, as targets get further apart, obscurin begins acting as a spring and requires progressively more energy to further elongate.
Collapse
Affiliation(s)
- Jacob A Whitley
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, 22807
| | - Aidan M Ex-Willey
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, 22807.,Department of Physiology and Cell Biology, Wexner Medical Center, Ohio State University, Columbus, Ohio, 43210
| | - Daniel R Marzolf
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, 22807
| | - Maegen A Ackermann
- Department of Physiology and Cell Biology, Wexner Medical Center, Ohio State University, Columbus, Ohio, 43210
| | - Anthony L Tongen
- Department of Mathematics and Statistics, James Madison University, Harrisonburg, Virginia, 22807
| | - Oleksandr Kokhan
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, 22807
| | - Nathan T Wright
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, 22807
| |
Collapse
|
11
|
Savarese M, Sarparanta J, Vihola A, Udd B, Hackman P. Increasing Role of Titin Mutations in Neuromuscular Disorders. J Neuromuscul Dis 2018; 3:293-308. [PMID: 27854229 PMCID: PMC5123623 DOI: 10.3233/jnd-160158] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The TTN gene with 363 coding exons encodes titin, a giant muscle protein spanning from the Z-disk to the M-band within the sarcomere. Mutations in the TTN gene have been associated with different genetic disorders, including hypertrophic and dilated cardiomyopathy and several skeletal muscle diseases. Before the introduction of next generation sequencing (NGS) methods, the molecular analysis of TTN has been laborious, expensive and not widely used, resulting in a limited number of mutations identified. Recent studies however, based on the use of NGS strategies, give evidence of an increasing number of rare and unique TTN variants. The interpretation of these rare variants of uncertain significance (VOUS) represents a challenge for clinicians and researchers. The main aim of this review is to describe the wide spectrum of muscle diseases caused by TTN mutations so far determined, summarizing the molecular findings as well as the clinical data, and to highlight the importance of joint efforts to respond to the challenges arising from the use of NGS. An international collaboration through a clinical and research consortium and the development of a single accessible database listing variants in the TTN gene, identified by high throughput approaches, may be the key to a better assessment of titinopathies and to systematic genotype– phenotype correlation studies.
Collapse
Affiliation(s)
- Marco Savarese
- Folkhälsan Institute of Genetics and Department of Medical Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland
| | - Jaakko Sarparanta
- Folkhälsan Institute of Genetics and Department of Medical Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland.,Albert Einstein College of Medicine, Departments of Medicine- Endocrinology and Molecular Pharmacology, Bronx, NY, USA
| | - Anna Vihola
- Folkhälsan Institute of Genetics and Department of Medical Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland
| | - Bjarne Udd
- Folkhälsan Institute of Genetics and Department of Medical Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland.,Neuromuscular Research Center, University of Tampere and Tampere University Hospital, Tampere, Finland.,Department of Neurology, Vaasa Central Hospital, Vaasa, Finland
| | - Peter Hackman
- Folkhälsan Institute of Genetics and Department of Medical Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland
| |
Collapse
|
12
|
Laddach A, Gautel M, Fraternali F. TITINdb-a computational tool to assess titin's role as a disease gene. Bioinformatics 2017; 33:3482-3485. [PMID: 29077808 PMCID: PMC5860166 DOI: 10.1093/bioinformatics/btx424] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 06/15/2017] [Accepted: 07/03/2017] [Indexed: 01/22/2023] Open
Abstract
SUMMARY Large numbers of rare and unique titin missense variants have been discovered in both healthy and disease cohorts, thus the correct classification of variants as pathogenic or non-pathogenic has become imperative. Due to titin's large size (363 coding exons), current web applications are unable to map titin variants to domain structures. Here, we present a web application, TITINdb, which integrates titin structure, variant, sequence and isoform information, along with pre-computed predictions of the impact of non-synonymous single nucleotide variants, to facilitate the correct classification of titin variants. AVAILABILITY AND IMPLEMENTATION TITINdb can be freely accessed at http://fraternalilab.kcl.ac.uk/TITINdb. CONTACT franca.fraternali@kcl.ac.uk. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
Collapse
Affiliation(s)
- Anna Laddach
- Randall Division of Cell and Molecular Biophysics, King’s College London BHF Centre of Research Excellence, London, UK
| | - Mathias Gautel
- Randall Division of Cell and Molecular Biophysics, King’s College London BHF Centre of Research Excellence, London, UK
| | - Franca Fraternali
- Randall Division of Cell and Molecular Biophysics, King’s College London BHF Centre of Research Excellence, London, UK
| |
Collapse
|
13
|
Rossi D, Palmio J, Evilä A, Galli L, Barone V, Caldwell TA, Policke RA, Aldkheil E, Berndsen CE, Wright NT, Malfatti E, Brochier G, Pierantozzi E, Jordanova A, Guergueltcheva V, Romero NB, Hackman P, Eymard B, Udd B, Sorrentino V. A novel FLNC frameshift and an OBSCN variant in a family with distal muscular dystrophy. PLoS One 2017; 12:e0186642. [PMID: 29073160 PMCID: PMC5657976 DOI: 10.1371/journal.pone.0186642] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 10/04/2017] [Indexed: 11/30/2022] Open
Abstract
A novel FLNC c.5161delG (p.Gly1722ValfsTer61) mutation was identified in two members of a French family affected by distal myopathy and in one healthy relative. This FLNC c.5161delG mutation is one nucleotide away from a previously reported FLNC mutation (c.5160delC) that was identified in patients and in asymptomatic carriers of three Bulgarian families with distal muscular dystrophy, indicating a low penetrance of the FLNC frameshift mutations. Given these similarities, we believe that the two FLNC mutations alone can be causative of distal myopathy without full penetrance. Moreover, comparative analysis of the clinical manifestations indicates that patients of the French family show an earlier onset and a complete segregation of the disease. As a possible explanation of this, the two French patients also carry a OBSCN c.13330C>T (p.Arg4444Trp) mutation. The p.Arg4444Trp variant is localized within the OBSCN Ig59 domain that, together with Ig58, binds to the ZIg9/ZIg10 domains of titin at Z-disks. Structural and functional studies indicate that this OBSCN p.Arg4444Trp mutation decreases titin binding by ~15-fold. On this line, we suggest that the combination of the OBSCN p.Arg4444Trp variant and of the FLNC c.5161delG mutation, can cooperatively affect myofibril stability and increase the penetrance of muscular dystrophy in the French family.
Collapse
Affiliation(s)
- Daniela Rossi
- Molecular Medicine Section, Department of Molecular and Developmental Medicine, University of Siena and Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Johanna Palmio
- Neuromuscular Research Center, Tampere University and University Hospital, Tampere, Finland
| | - Anni Evilä
- Folkhälsan Institute of Genetics and Department of Medical Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland
| | - Lucia Galli
- Molecular Medicine Section, Department of Molecular and Developmental Medicine, University of Siena and Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Virginia Barone
- Molecular Medicine Section, Department of Molecular and Developmental Medicine, University of Siena and Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Tracy A. Caldwell
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, United States of America
| | - Rachel A. Policke
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, United States of America
| | - Esraa Aldkheil
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, United States of America
| | - Christopher E. Berndsen
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, United States of America
| | - Nathan T. Wright
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, United States of America
| | - Edoardo Malfatti
- Neuromuscular Morphology Unit, and Reference Center for Neuromuscular Diseases, Myology Institute, Groupe Hospitalier La Pitié-Salpêtrière, Paris, France
| | - Guy Brochier
- Neuromuscular Morphology Unit, and Reference Center for Neuromuscular Diseases, Myology Institute, Groupe Hospitalier La Pitié-Salpêtrière, Paris, France
| | - Enrico Pierantozzi
- Molecular Medicine Section, Department of Molecular and Developmental Medicine, University of Siena and Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Albena Jordanova
- Molecular Neurogenomics Group, University of Antwerp, Antwerp, Belgium
- Molecular Medicine Center, Department of Medical Chemistry and Biochemistry, Medical University-Sofia, Sofia, Bulgaria
| | | | - Norma Beatriz Romero
- Neuromuscular Morphology Unit, and Reference Center for Neuromuscular Diseases, Myology Institute, Groupe Hospitalier La Pitié-Salpêtrière, Paris, France
| | - Peter Hackman
- Folkhälsan Institute of Genetics and Department of Medical Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland
| | - Bruno Eymard
- Neuromuscular Morphology Unit, and Reference Center for Neuromuscular Diseases, Myology Institute, Groupe Hospitalier La Pitié-Salpêtrière, Paris, France
| | - Bjarne Udd
- Neuromuscular Research Center, Tampere University and University Hospital, Tampere, Finland
- Folkhälsan Institute of Genetics and Department of Medical Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland
- Department of Neurology, Vaasa Central Hospital, Vaasa, Finland
| | - Vincenzo Sorrentino
- Molecular Medicine Section, Department of Molecular and Developmental Medicine, University of Siena and Azienda Ospedaliera Universitaria Senese, Siena, Italy
- * E-mail:
| |
Collapse
|
14
|
Hu LYR, Ackermann MA, Hecker PA, Prosser BL, King B, O’Connell KA, Grogan A, Meyer LC, Berndsen CE, Wright NT, Jonathan Lederer W, Kontrogianni-Konstantopoulos A. Deregulated Ca 2+ cycling underlies the development of arrhythmia and heart disease due to mutant obscurin. SCIENCE ADVANCES 2017; 3:e1603081. [PMID: 28630914 PMCID: PMC5462502 DOI: 10.1126/sciadv.1603081] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 04/17/2017] [Indexed: 05/05/2023]
Abstract
Obscurins are cytoskeletal proteins with structural and regulatory roles encoded by OBSCN. Mutations in OBSCN are associated with the development of hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM). Specifically, the R4344Q mutation present in immunoglobulin domain 58 (Ig58) was the first to be linked with the development of HCM. To assess the effects of R4344Q in vivo, we generated the respective knock-in mouse model. Mutant obscurins are expressed and incorporated normally into sarcomeres. The expression patterns of sarcomeric and Ca2+-cycling proteins are unaltered in sedentary 1-year-old knock-in myocardia, with the exception of sarco/endoplasmic reticulum Ca2+ adenosine triphosphatase 2 (SERCA2) and pentameric phospholamban whose levels are significantly increased and decreased, respectively. Isolated cardiomyocytes from 1-year-old knock-in hearts exhibit increased Ca2+-transients and Ca2+-load in the sarcoplasmic reticulum and faster contractility kinetics. Moreover, sedentary 1-year-old knock-in animals develop tachycardia accompanied by premature ventricular contractions, whereas 2-month-old knock-in animals subjected to pressure overload develop a DCM-like phenotype. Structural analysis revealed that the R4344Q mutation alters the distribution of electrostatic charges over the Ig58 surface, thus interfering with its binding capabilities. Consistent with this, wild-type Ig58 interacts with phospholamban modestly, and this interaction is markedly enhanced in the presence of R4344Q. Together, our studies demonstrate that under sedentary conditions, the R4344Q mutation results in Ca2+ deregulation and spontaneous arrhythmia, whereas in the presence of chronic, pathological stress, it leads to cardiac remodeling and dilation. We postulate that enhanced binding between mutant obscurins and phospholamban leads to SERCA2 disinhibition, which may underlie the observed pathological alterations.
Collapse
Affiliation(s)
- Li-Yen R. Hu
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Baltimore, MD 21201, USA
| | - Maegen A. Ackermann
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Baltimore, MD 21201, USA
| | - Peter A. Hecker
- Division of Cardiovascular Medicine, Department of Medicine, University of Maryland, Baltimore, Baltimore, MD 21201, USA
| | - Benjamin L. Prosser
- Department of Physiology, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Department of Physiology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Brendan King
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Baltimore, MD 21201, USA
| | - Kelly A. O’Connell
- Division of Cardiovascular Medicine, Department of Medicine, University of Maryland, Baltimore, Baltimore, MD 21201, USA
| | - Alyssa Grogan
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Baltimore, MD 21201, USA
| | - Logan C. Meyer
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, VA 22807, USA
| | - Christopher E. Berndsen
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, VA 22807, USA
| | - Nathan T. Wright
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, VA 22807, USA
| | - W. Jonathan Lederer
- Department of Physiology, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | | |
Collapse
|
15
|
An eccentric calpain, CAPN3/p94/calpain-3. Biochimie 2016; 122:169-87. [DOI: 10.1016/j.biochi.2015.09.010] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 09/07/2015] [Indexed: 01/09/2023]
|
16
|
Caldwell TA, Sumner I, Wright NT. Mechanical dissociation of the M-band titin/obscurin complex is directionally dependent. FEBS Lett 2015; 589:1735-9. [PMID: 26001486 DOI: 10.1016/j.febslet.2015.05.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 05/08/2015] [Accepted: 05/11/2015] [Indexed: 11/29/2022]
Abstract
Titin and obscurin, two giant muscle proteins, bind to each other in an antiparallel Ig-Ig fashion at the M-band. This interaction must be able to withstand the mechanical strain that the M-band typically experiences and remain intact. The mechanical force on these domains is likely exerted along one of two axes: a longitudinal axis, resulting in a 'shearing' force, or a lateral axis, resulting in a 'peeling' force. Here we present molecular dynamics data suggesting that these forces result in distinct unraveling pathways of the titin/obscurin complex and that peeling the domains apart requires less work and force.
Collapse
Affiliation(s)
- Tracy A Caldwell
- Department of Chemistry and Biochemistry, James Madison University, 901 Carrier Dr., Harrisonburg, VA 22807, United States
| | - Isaiah Sumner
- Department of Chemistry and Biochemistry, James Madison University, 901 Carrier Dr., Harrisonburg, VA 22807, United States
| | - Nathan T Wright
- Department of Chemistry and Biochemistry, James Madison University, 901 Carrier Dr., Harrisonburg, VA 22807, United States.
| |
Collapse
|
17
|
Charton K, Sarparanta J, Vihola A, Milic A, Jonson PH, Suel L, Luque H, Boumela I, Richard I, Udd B. CAPN3-mediated processing of C-terminal titin replaced by pathological cleavage in titinopathy. Hum Mol Genet 2015; 24:3718-31. [DOI: 10.1093/hmg/ddv116] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 03/30/2015] [Indexed: 02/03/2023] Open
|