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Hashimoto K, Ohira M, Kodama A, Kimoto M, Inoue M, Toné S, Usui Y, Hanashima A, Goto T, Ogura Y, Ujihara Y, Mohri S. Loss of connectin novex-3 leads to heart dysfunction associated with impaired cardiomyocyte proliferation and abnormal nuclear mechanics. Sci Rep 2024; 14:13727. [PMID: 38877142 PMCID: PMC11178842 DOI: 10.1038/s41598-024-64608-1] [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: 08/31/2023] [Accepted: 06/11/2024] [Indexed: 06/16/2024] Open
Abstract
Connectin (also known as titin) is a giant striated muscle protein that functions as a molecular spring by providing elasticity to the sarcomere. Novex-3 is a short splice variant of connectin whose physiological function remains unknown. We have recently demonstrated using in vitro analyses that in addition to sarcomere expression, novex-3 was also expressed in cardiomyocyte nuclei exclusively during fetal life, where it provides elasticity/compliance to cardiomyocyte nuclei and promotes cardiomyocyte proliferation in the fetus, suggesting a non-sarcomeric function. Here, we analyzed novex-3 knockout mice to assess the involvement of this function in cardiac pathophysiology in vivo. Deficiency of novex-3 compromised fetal cardiomyocyte proliferation and induced the enlargement of individual cardiomyocytes in neonates. In adults, novex-3 deficiency resulted in chamber dilation and systolic dysfunction, associated with Ca2+ dysregulation, resulting in a reduced life span. Mechanistic analyses revealed a possible association between impaired proliferation and abnormal nuclear mechanics, including stiffer nuclei positioned peripherally with stabilized circumnuclear microtubules in knockout cardiomyocytes. Although the underlying causal relationships were not fully elucidated, these data show that novex-3 has a vital non-sarcomeric function in cardiac pathophysiology and serves as an early contributor to cardiomyocyte proliferation.
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Affiliation(s)
- Ken Hashimoto
- First Department of Physiology, Kawasaki Medical School, Kurashiki, 701-0192, Japan.
| | - Momoko Ohira
- First Department of Physiology, Kawasaki Medical School, Kurashiki, 701-0192, Japan
| | - Aya Kodama
- First Department of Physiology, Kawasaki Medical School, Kurashiki, 701-0192, Japan
| | - Misaki Kimoto
- First Department of Physiology, Kawasaki Medical School, Kurashiki, 701-0192, Japan
| | - Mariko Inoue
- Central Research Institute, Kawasaki Medical School, Kurashiki, 701-0192, Japan
| | - Shigenobu Toné
- Laboratory of Molecular Developmental Biology, Graduate School of Science and Engineering, Tokyo Denki University, Hatoyama, Saitama, 350-0394, Japan
| | - Yuu Usui
- First Department of Physiology, Kawasaki Medical School, Kurashiki, 701-0192, Japan
| | - Akira Hanashima
- First Department of Physiology, Kawasaki Medical School, Kurashiki, 701-0192, Japan
| | - Takato Goto
- Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, 466-8555, Japan
| | - Yuhei Ogura
- Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, 466-8555, Japan
| | - Yoshihiro Ujihara
- Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, 466-8555, Japan
| | - Satoshi Mohri
- First Department of Physiology, Kawasaki Medical School, Kurashiki, 701-0192, Japan
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2
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Kahsay A, Dennhag N, Liu JX, Nord H, Rönnbäck H, Thorell AE, von Hofsten J, Pedrosa Domellöf F. Obscurin Maintains Myofiber Identity in Extraocular Muscles. Invest Ophthalmol Vis Sci 2024; 65:19. [PMID: 38334702 PMCID: PMC10860686 DOI: 10.1167/iovs.65.2.19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Accepted: 01/12/2024] [Indexed: 02/10/2024] Open
Abstract
Purpose The cytoskeleton of the extraocular muscles (EOMs) is significantly different from that of other muscles. We aimed to investigate the role of obscurin, a fundamental cytoskeletal protein, in the EOMs. Methods The distribution of obscurin in human and zebrafish EOMs was compared using immunohistochemistry. The two obscurin genes in zebrafish, obscna and obscnb, were knocked out using CRISPR/Cas9, and the EOMs were investigated using immunohistochemistry, qPCR, and in situ hybridization. The optokinetic reflex (OKR) in five-day-old larvae and adult obscna-/-;obscnb-/- and sibling control zebrafish was analyzed. Swimming distance was recorded at the same age. Results The obscurin distribution pattern was similar in human and zebrafish EOMs. The proportion of slow and fast myofibers was reduced in obscna-/-;obscnb-/- zebrafish EOMs but not in trunk muscle, whereas the number of myofibers containing cardiac myosin myh7 was significantly increased in EOMs of obscurin double mutants. Loss of obscurin resulted in less OKRs in zebrafish larvae but not in adult zebrafish. Conclusions Obscurin expression is conserved in normal human and zebrafish EOMs. Loss of obscurin induces a myofiber type shift in the EOMs, with upregulation of cardiac myosin heavy chain, myh7, showing an adaptation strategy in EOMs. Our model will facilitate further studies in conditions related to obscurin.
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Affiliation(s)
- Abraha Kahsay
- Department of Integrative Medical Biology (IMB), Umeå University, Umeå, Sweden
- Department of Clinical Sciences, Ophthalmology, Umeå University, Umeå, Sweden
| | - Nils Dennhag
- Department of Integrative Medical Biology (IMB), Umeå University, Umeå, Sweden
- Department of Clinical Sciences, Ophthalmology, Umeå University, Umeå, Sweden
| | - Jing-Xia Liu
- Department of Integrative Medical Biology (IMB), Umeå University, Umeå, Sweden
| | - Hanna Nord
- Department of Integrative Medical Biology (IMB), Umeå University, Umeå, Sweden
| | - Hugo Rönnbäck
- Department of Clinical Sciences, Ophthalmology, Umeå University, Umeå, Sweden
| | | | - Jonas von Hofsten
- Department of Integrative Medical Biology (IMB), Umeå University, Umeå, Sweden
| | - Fatima Pedrosa Domellöf
- Department of Integrative Medical Biology (IMB), Umeå University, Umeå, Sweden
- Department of Clinical Sciences, Ophthalmology, Umeå University, Umeå, Sweden
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3
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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.
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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.
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4
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Mandigers PJJ, Stehling O, Vos-Loohuis M, Van Steenbeek FG, Lill R, Leegwater PA. A novel IBA57 variant is associated with mitochondrial iron-sulfur protein deficiency and necrotizing myelopathy in dogs. Front Genet 2023; 14:1190222. [PMID: 37588046 PMCID: PMC10425596 DOI: 10.3389/fgene.2023.1190222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 06/27/2023] [Indexed: 08/18/2023] Open
Abstract
Introduction: Hereditary necrotizing myelopathy (HNM) in young Kooiker dogs is characterized by progressive ataxia and paralysis with autosomal recessive inheritance. The basic genetic defect is unknown. We investigated the possible cause by a genome-wide analysis using six affected and 17 unrelated unaffected Kooiker dogs and by functional follow-up studies. Method: The HNM locus was mapped by a case-control study using a dense SNP array and confirmed by linkage analysis of two pedigrees. The gene exons in the critical region were analyzed by next-generation sequencing. The functional effect of the candidate canine IBA57 pathogenic variant was biochemically examined in an established HeLa cell culture model in which the endogenous IBA75 gene product was depleted by RNAi. Results: The basic defect was localized in the centromeric 5 Mb region of canine chromosome 14. The most associated SNP co-segregated fully with HNM and reached an LOD score of 6.1. A candidate pathogenic mutation was found in the iron-sulfur cluster assembly gene IBA57 and led to the amino acid substitution R147W. The expression of human IBA57 harboring the canine R147W exchange could only partially restore the biochemical defects of several mitochondrial [4Fe-4S] proteins upon IBA57 depletion, showing that the mutant protein is functionally impaired. Discussion: Pathogenic variants in human IBA57 cause multiple mitochondrial dysfunction syndrome 3 (MMDS3), a neurodegenerative disorder with distant similarities to HNM. The incomplete functional complementation of IBA57-depleted human cells by IBA57-R147W identifies the DNA mutation in affected Kooiker dogs as the genetic cause of HNM. Our findings further expand the phenotypic spectrum of pathogenic IBA57 variants.
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Affiliation(s)
- Paul J. J. Mandigers
- Expertise Centre of Genetics, Department of Clinical Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
| | - Oliver Stehling
- Institut für Zytobiologie und Zytopathologie and Center for Synthetic Microbiology Synmikro, Philipps-Universität Marburg, Marburg, Germany
| | - Manon Vos-Loohuis
- Expertise Centre of Genetics, Department of Clinical Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
| | - Frank G. Van Steenbeek
- Expertise Centre of Genetics, Department of Clinical Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
| | - Roland Lill
- Institut für Zytobiologie und Zytopathologie and Center for Synthetic Microbiology Synmikro, Philipps-Universität Marburg, Marburg, Germany
| | - Peter A. Leegwater
- Expertise Centre of Genetics, Department of Clinical Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
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5
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Koch D, Kho AL, Fukuzawa A, Alexandrovich A, Vanaanen KJ, Beavil A, Pfuhl M, Rees M, Gautel M. Obscurin Rho GEF domains are phosphorylated by MST-family kinases but do not exhibit nucleotide exchange factor activity towards Rho GTPases in vitro. PLoS One 2023; 18:e0284453. [PMID: 37079638 PMCID: PMC10118190 DOI: 10.1371/journal.pone.0284453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 04/01/2023] [Indexed: 04/21/2023] Open
Abstract
Obscurin is a giant muscle protein (>800 kDa) featuring multiple signalling domains, including an SH3-DH-PH domain triplet from the Trio-subfamily of guanosine nucleotide exchange factors (GEFs). While previous research suggests that these domains can activate the small GTPases RhoA and RhoQ in cells, in vitro characterization of these interactions using biophysical techniques has been hampered by the intrinsic instability of obscurin GEF domains. To study substrate specificity, mechanism and regulation of obscurin GEF function by individual domains, we successfully optimized recombinant production of obscurin GEF domains and found that MST-family kinases phosphorylate the obscurin DH domain at Thr5798. Despite extensive testing of multiple GEF domain fragments, we did not detect any nucleotide exchange activity in vitro against 9 representative small GTPases. Bioinformatic analyses show that obscurin differs from other Trio-subfamily GEFs in several important aspects. While further research is necessary to evaluate obscurin GEF activity in vivo, our results indicate that obscurin has atypical GEF domains that, if catalytically active at all, are subject to complex regulation.
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Affiliation(s)
- Daniel Koch
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Ay Lin Kho
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Atsushi Fukuzawa
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Alexander Alexandrovich
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Kutti J. Vanaanen
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Andrew Beavil
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Mark Pfuhl
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Martin Rees
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Mathias Gautel
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, United Kingdom
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6
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Grogan A, Huang W, Brong A, Kane MA, Kontrogianni-Konstantopoulos A. Alterations in cytoskeletal and Ca 2+ cycling regulators in atria lacking the obscurin Ig58/59 module. Front Cardiovasc Med 2023; 10:1085840. [PMID: 37304957 PMCID: PMC10251194 DOI: 10.3389/fcvm.2023.1085840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 01/26/2023] [Indexed: 06/13/2023] Open
Abstract
Introduction Obscurin (720-870 kDa) is a giant cytoskeletal and signaling protein that possesses both structural and regulatory functions in striated muscles. Immunoglobulin domains 58/59 (Ig58/59) of obscurin bind to a diverse set of proteins that are essential for the proper structure and function of the heart, including giant titin, novex-3, and phospholamban (PLN). Importantly, the pathophysiological significance of the Ig58/59 module has been further underscored by the discovery of several mutations within Ig58/59 that are linked to various forms of myopathy in humans. We previously generated a constitutive deletion mouse model, Obscn-ΔIg58/59, that expresses obscurin lacking Ig58/59, and characterized the effects of this deletion on cardiac morphology and function through aging. Our findings demonstrated that Obscn-ΔIg58/59 male animals develop severe arrhythmia, primarily manifesting as episodes of junctional escape and spontaneous loss of regular p-waves, reminiscent of human atrial fibrillation, accompanied by significant atrial enlargement that progresses in severity with aging. Methods and Results To comprehensively characterize the molecular alterations responsible for these pathologies, we performed proteomic and phospho-proteomic analyses in aging Obscn-ΔIg58/59 atria. Our studies revealed extensive and novel alterations in the expression and phosphorylation profile of major cytoskeletal proteins, Ca2+ regulators, and Z-disk associated protein complexes in the Obscn-ΔIg58/59 atria through aging. Discussion These studies implicate obscurin, particularly the Ig58/59 module, as an essential regulator of the Z-disk associated cytoskeleton and Ca2+ cycling in the atria and provide new molecular insights into the development of atrial fibrillation and remodeling.
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Affiliation(s)
- Alyssa Grogan
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, MD, United States
| | - Weiliang Huang
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD, United States
| | - Annie Brong
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, MD, United States
| | - Maureen A. Kane
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD, United States
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7
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Noureddine M, Gehmlich K. Structural and signaling proteins in the Z-disk and their role in cardiomyopathies. Front Physiol 2023; 14:1143858. [PMID: 36935760 PMCID: PMC10017460 DOI: 10.3389/fphys.2023.1143858] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 02/21/2023] [Indexed: 03/06/2023] Open
Abstract
The sarcomere is the smallest functional unit of muscle contraction. It is delineated by a protein-rich structure known as the Z-disk, alternating with M-bands. The Z-disk anchors the actin-rich thin filaments and plays a crucial role in maintaining the mechanical stability of the cardiac muscle. A multitude of proteins interact with each other at the Z-disk and they regulate the mechanical properties of the thin filaments. Over the past 2 decades, the role of the Z-disk in cardiac muscle contraction has been assessed widely, however, the impact of genetic variants in Z-disk proteins has still not been fully elucidated. This review discusses the various Z-disk proteins (alpha-actinin, filamin C, titin, muscle LIM protein, telethonin, myopalladin, nebulette, and nexilin) and Z-disk-associated proteins (desmin, and obscurin) and their role in cardiac structural stability and intracellular signaling. This review further explores how genetic variants of Z-disk proteins are linked to inherited cardiac conditions termed cardiomyopathies.
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Affiliation(s)
- Maya Noureddine
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- *Correspondence: Maya Noureddine, ; Katja Gehmlich,
| | - Katja Gehmlich
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence Oxford, University of Oxford, Oxford, United Kingdom
- *Correspondence: Maya Noureddine, ; Katja Gehmlich,
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8
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Exploring the Potential of Symmetric Exon Deletion to Treat Non-Ischemic Dilated Cardiomyopathy by Removing Frameshift Mutations in TTN. Genes (Basel) 2022; 13:genes13061093. [PMID: 35741855 PMCID: PMC9222585 DOI: 10.3390/genes13061093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 05/30/2022] [Accepted: 06/10/2022] [Indexed: 11/17/2022] Open
Abstract
Non-ischemic dilated cardiomyopathy (DCM) is one of the most frequent pathologies requiring cardiac transplants. Even though the etiology of this disease is complex, frameshift mutations in the giant sarcomeric protein Titin could explain up to 25% of the familial and 18% of the sporadic cases of DCM. Many studies have shown the potential of genome editing using CRISPR/Cas9 to correct truncating mutations in sarcomeric proteins and have established the grounds for myoediting. However, these therapies are still in an immature state, with only few studies showing an efficient treatment of cardiac diseases. This publication hypothesizes that the Titin (TTN)-specific gene structure allows the application of myoediting approaches in a broad range of locations to reframe TTNtvvariants and to treat DCM patients. Additionally, to pave the way for the generation of efficient myoediting approaches for DCM, we screened and selected promising target locations in TTN. We conceptually explored the deletion of symmetric exons as a therapeutic approach to restore TTN’s reading frame in cases of frameshift mutations. We identified a set of 94 potential candidate exons of TTN that we consider particularly suitable for this therapeutic deletion. With this study, we aim to contribute to the development of new therapies to efficiently treat titinopathies and other diseases caused by mutations in genes encoding proteins with modular structures, e.g., Obscurin.
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9
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Cleary SR, Fang X, Cho EE, Pribadi MP, Seflova J, Beach JR, Kekenes-Huskey PM, Robia SL. Inhibitory and stimulatory micropeptides preferentially bind to different conformations of the cardiac calcium pump. J Biol Chem 2022; 298:102060. [PMID: 35605666 PMCID: PMC9218510 DOI: 10.1016/j.jbc.2022.102060] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 05/09/2022] [Accepted: 05/13/2022] [Indexed: 12/04/2022] Open
Abstract
The ATP-dependent ion pump sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) sequesters Ca2+ in the endoplasmic reticulum to establish a reservoir for cell signaling. Because of its central importance in physiology, the activity of this transporter is tightly controlled via direct interactions with tissue-specific regulatory micropeptides that tune SERCA function to match changing physiological conditions. In the heart, the micropeptide phospholamban (PLB) inhibits SERCA, while dwarf open reading frame (DWORF) stimulates SERCA. These competing interactions determine cardiac performance by modulating the amplitude of Ca2+ signals that drive the contraction/relaxation cycle. We hypothesized that the functions of these peptides may relate to their reciprocal preferences for SERCA binding; SERCA binds PLB more avidly at low cytoplasmic [Ca2+] but binds DWORF better when [Ca2+] is high. In the present study, we demonstrated this opposing Ca2+ sensitivity is due to preferential binding of DWORF and PLB to different intermediate states that SERCA samples during the Ca2+ transport cycle. We show PLB binds best to the SERCA E1-ATP state, which prevails at low [Ca2+]. In contrast, DWORF binds most avidly to E1P and E2P states that are more populated when Ca2+ is elevated. Moreover, FRET microscopy revealed dynamic shifts in SERCA–micropeptide binding equilibria during cellular Ca2+ elevations. A computational model showed that DWORF exaggerates changes in PLB–SERCA binding during the cardiac cycle. These results suggest a mechanistic basis for inhibitory versus stimulatory micropeptide function, as well as a new role for DWORF as a modulator of dynamic oscillations of PLB–SERCA regulatory interactions.
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Affiliation(s)
- Sean R Cleary
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Xuan Fang
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Ellen E Cho
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Marsha P Pribadi
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Jaroslava Seflova
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Jordan R Beach
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Peter M Kekenes-Huskey
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Seth L Robia
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA.
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10
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Bang ML, Bogomolovas J, Chen J. Understanding the molecular basis of cardiomyopathy. Am J Physiol Heart Circ Physiol 2022; 322:H181-H233. [PMID: 34797172 PMCID: PMC8759964 DOI: 10.1152/ajpheart.00562.2021] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 11/16/2021] [Accepted: 11/16/2021] [Indexed: 02/03/2023]
Abstract
Inherited cardiomyopathies are a major cause of mortality and morbidity worldwide and can be caused by mutations in a wide range of proteins located in different cellular compartments. The present review is based on Dr. Ju Chen's 2021 Robert M. Berne Distinguished Lectureship of the American Physiological Society Cardiovascular Section, in which he provided an overview of the current knowledge on the cardiomyopathy-associated proteins that have been studied in his laboratory. The review provides a general summary of the proteins in different compartments of cardiomyocytes associated with cardiomyopathies, with specific focus on the proteins that have been studied in Dr. Chen's laboratory.
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Affiliation(s)
- Marie-Louise Bang
- Institute of Genetic and Biomedical Research (IRGB), National Research Council (CNR), Milan Unit, Milan, Italy
- IRCCS Humanitas Research Hospital, Rozzano (Milan), Italy
| | - Julius Bogomolovas
- Division of Cardiovascular Medicine, Department of Medicine Cardiology, University of California, San Diego, La Jolla, California
| | - Ju Chen
- Division of Cardiovascular Medicine, Department of Medicine Cardiology, University of California, San Diego, La Jolla, California
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11
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Pierantozzi E, Szentesi P, Paolini C, Dienes B, Fodor J, Oláh T, Colombini B, Rassier DE, Rubino EM, Lange S, Rossi D, Csernoch L, Bagni MA, Reggiani C, Sorrentino V. Impaired Intracellular Ca 2+ Dynamics, M-Band and Sarcomere Fragility in Skeletal Muscles of Obscurin KO Mice. Int J Mol Sci 2022; 23:1319. [PMID: 35163243 PMCID: PMC8835721 DOI: 10.3390/ijms23031319] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 01/19/2022] [Accepted: 01/20/2022] [Indexed: 12/16/2022] Open
Abstract
Obscurin is a giant sarcomeric protein expressed in striated muscles known to establish several interactions with other proteins of the sarcomere, but also with proteins of the sarcoplasmic reticulum and costameres. Here, we report experiments aiming to better understand the contribution of obscurin to skeletal muscle fibers, starting with a detailed characterization of the diaphragm muscle function, which we previously reported to be the most affected muscle in obscurin (Obscn) KO mice. Twitch and tetanus tension were not significantly different in the diaphragm of WT and Obscn KO mice, while the time to peak (TTP) and half relaxation time (HRT) were prolonged. Differences in force-frequency and force-velocity relationships and an enhanced fatigability are observed in an Obscn KO diaphragm with respect to WT controls. Voltage clamp experiments show that a sarcoplasmic reticulum's Ca2+ release and SERCA reuptake rates were decreased in muscle fibers from Obscn KO mice, suggesting that an impairment in intracellular Ca2+ dynamics could explain the observed differences in the TTP and HRT in the diaphragm. In partial contrast with previous observations, Obscn KO mice show a normal exercise tolerance, but fiber damage, the altered sarcomere ultrastructure and M-band disarray are still observed after intense exercise.
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Affiliation(s)
- Enrico Pierantozzi
- Department of Molecular and Developmental Medicine, Molecular Medicine Section, University of Siena, 53100 Siena, Italy; (E.P.); (E.M.R.); (D.R.)
| | - Péter Szentesi
- Department of Physiology, Faculty of Medicine, University of Debrecen, H-4002 Debrecen, Hungary; (P.S.); (B.D.); (J.F.); (T.O.); (L.C.)
| | - Cecilia Paolini
- Department of Neuroscience, Imaging and Clinical Sciences, University Gabriele d’ Annunzio of Chieti, 66100 Chieti, Italy;
| | - Beatrix Dienes
- Department of Physiology, Faculty of Medicine, University of Debrecen, H-4002 Debrecen, Hungary; (P.S.); (B.D.); (J.F.); (T.O.); (L.C.)
| | - János Fodor
- Department of Physiology, Faculty of Medicine, University of Debrecen, H-4002 Debrecen, Hungary; (P.S.); (B.D.); (J.F.); (T.O.); (L.C.)
| | - Tamás Oláh
- Department of Physiology, Faculty of Medicine, University of Debrecen, H-4002 Debrecen, Hungary; (P.S.); (B.D.); (J.F.); (T.O.); (L.C.)
| | - Barbara Colombini
- Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy; (B.C.); (M.A.B.)
| | - Dilson E. Rassier
- Department of Kinesiology and Physical Education, McGill University, Montreal, QC H2W 1S4, Canada;
| | - Egidio Maria Rubino
- Department of Molecular and Developmental Medicine, Molecular Medicine Section, University of Siena, 53100 Siena, Italy; (E.P.); (E.M.R.); (D.R.)
| | - Stephan Lange
- Biomedical Research Facility 2, School of Medicine, University of California, La Jolla, CA 92093, USA;
- Department of Molecular and Clinical Medicine, Institute of Medicine, University of Gothenburg, 413 45 Gothenburg, Sweden
| | - Daniela Rossi
- Department of Molecular and Developmental Medicine, Molecular Medicine Section, University of Siena, 53100 Siena, Italy; (E.P.); (E.M.R.); (D.R.)
| | - László Csernoch
- Department of Physiology, Faculty of Medicine, University of Debrecen, H-4002 Debrecen, Hungary; (P.S.); (B.D.); (J.F.); (T.O.); (L.C.)
| | - Maria Angela Bagni
- Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy; (B.C.); (M.A.B.)
| | - Carlo Reggiani
- Department of Biomedical Science, University of Padova, 35121 Padova, Italy;
- Science and Research Center Koper, Institute for Kinesiology Research, 6000 Koper, Slovenia
| | - Vincenzo Sorrentino
- Department of Molecular and Developmental Medicine, Molecular Medicine Section, University of Siena, 53100 Siena, Italy; (E.P.); (E.M.R.); (D.R.)
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12
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Cabrera-Serrano M, Caccavelli L, Savarese M, Vihola A, Jokela M, Johari M, Capiod T, Madrange M, Bugiardini E, Brady S, Quinlivan R, Merve A, Scalco R, Hilton-Jones D, Houlden H, Ibrahim Aydin H, Ceylaner S, Vockley J, Taylor RL, Folland C, Kelly A, Goullee H, Ylikallio E, Auranen M, Tyynismaa H, Udd B, Forrest ARR, Davis MR, Bratkovic D, Manton N, Robertson T, McCombe P, Laing NG, Phillips L, de Lonlay P, Ravenscroft G. Bi-allelic loss-of-function OBSCN variants predispose individuals to severe recurrent rhabdomyolysis. Brain 2021; 145:3985-3998. [DOI: 10.1093/brain/awab484] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 12/04/2021] [Accepted: 12/10/2021] [Indexed: 11/14/2022] Open
Abstract
Abstract
Rhabdomyolysis is the acute breakdown of skeletal myofibres in response to an initiating factor, most commonly toxins and over exertion. A variety of genetic disorders predispose to rhabdomyolysis through different pathogenic mechanisms, particularly in patients with recurrent episodes. However, most cases remain without a genetic diagnosis. Here we present six patients who presented with severe and recurrent rhabdomyolysis, usually with onset in the teenage years; other features included a history of myalgia and muscle cramps. We identified ten bi-allelic loss-of-function variants in the gene encoding obscurin (OBSCN) predisposing individuals to recurrent rhabdomyolysis. We show reduced expression of OBSCN and loss of obscurin protein in patient muscle. Obscurin is proposed to be involved in SR function and Ca2+ handling. Patient cultured myoblasts appear more susceptible to starvation as evidenced by a greater decreased in SR Ca2+ content compared to control myoblasts. This likely reflects a lower efficiency when pumping Ca2+ back into the SR and/or a decrease in Ca2+ SR storage ability when metabolism is diminished. OSBCN variants have previously been associated with cardiomyopathies. None of the patients presented with a cardiomyopathy and cardiac examinations were normal in all cases in which cardiac function was assessed. There was also no history of cardiomyopathy in first degree relatives, in particular in any of the carrier parents. This cohort is relatively young, thus follow-up studies and the identification of additional cases with bi-allelic null OBSCN variants will further delineate OBSCN-related disease and the clinical course of disease.
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Affiliation(s)
- Macarena Cabrera-Serrano
- Harry Perkins Institute of Medical Research, Nedlands, WA, Australia
- Centre of Medical Research, University of Western Australia, Nedlands, WA, Australia
- Unidad de Enfermedades Neuromusculares. Servicio de Neurologia y Neurofisiologia. Hospital Virgen del Rocio, Sevilla, Spain
| | - Laure Caccavelli
- Inserm U1151, Institut Necker Enfants-Malades, Reference Center of Inherited Metabolic Diseases and MetabERN, Necker-Enfants-Malades Hospital, Paris University, Paris, France
| | - Marco Savarese
- Folkhälsan Research Center, Helsinki, Finland and Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Anna Vihola
- Folkhälsan Research Center, Helsinki, Finland and Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
- Tampere Neuromuscular Center, Tampere University Hospital, Tampere, Finland
| | - Manu Jokela
- Neuromuscular Research Center, Department of Neurology, Tampere University and University Hospital, Tampere, Finland
- Neurocenter, Department of Neurology, Clinical Neurosciences, Turku University Hospital and University of Turku, Turku, Finland
| | - Mridul Johari
- Folkhälsan Research Center, Helsinki, Finland and Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Thierry Capiod
- Inserm U1151, Institut Necker Enfants-Malades, Reference Center of Inherited Metabolic Diseases and MetabERN, Necker-Enfants-Malades Hospital, Paris University, Paris, France
| | - Marine Madrange
- Inserm U1151, Institut Necker Enfants-Malades, Reference Center of Inherited Metabolic Diseases and MetabERN, Necker-Enfants-Malades Hospital, Paris University, Paris, France
| | - Enrico Bugiardini
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, London, UK
| | - Stefen Brady
- Department of Neurology, Southmead Hospital, Bristol, UK
| | - Rosaline Quinlivan
- MRC Centre for Neuromuscular Diseases, University College Hospitals, London, UK
| | - Ashirwad Merve
- MRC Centre for Neuromuscular Diseases, University College Hospitals, London, UK
| | - Renata Scalco
- MRC Centre for Neuromuscular Diseases, University College Hospitals, London, UK
| | - David Hilton-Jones
- Neurosciences Group, Nuffield Department of Clinical Neurosciences, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Henry Houlden
- Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, London, UK
| | | | - Serdar Ceylaner
- Intergen Genetic Diagnosis and Research Center, Ankara, Turkey
| | - Jerry Vockley
- University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Rhonda L. Taylor
- Harry Perkins Institute of Medical Research, Nedlands, WA, Australia
- Centre of Medical Research, University of Western Australia, Nedlands, WA, Australia
| | - Chiara Folland
- Harry Perkins Institute of Medical Research, Nedlands, WA, Australia
- Centre of Medical Research, University of Western Australia, Nedlands, WA, Australia
| | - Aasta Kelly
- Harry Perkins Institute of Medical Research, Nedlands, WA, Australia
| | - Hayley Goullee
- Harry Perkins Institute of Medical Research, Nedlands, WA, Australia
- Centre of Medical Research, University of Western Australia, Nedlands, WA, Australia
| | - Emil Ylikallio
- Clinical Neurosciences, Neurology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland
| | - Mari Auranen
- Clinical Neurosciences, Neurology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Henna Tyynismaa
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland
- Neuroscience Center, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Bjarne Udd
- Folkhälsan Research Center, Helsinki, Finland and Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
- Tampere Neuromuscular Center, Tampere University Hospital, Tampere, Finland
| | - Alistair R. R. Forrest
- Harry Perkins Institute of Medical Research, Nedlands, WA, Australia
- Centre of Medical Research, University of Western Australia, Nedlands, WA, Australia
| | - Mark R. Davis
- Department of Diagnostic Genomics, PathWest Laboratory Medicine WA, Nedlands, WA, Australia
| | - Drago Bratkovic
- Metabolic Clinic, Women and Children’s Hospital, North Adelaide, SA, Australia
| | - Nicholas Manton
- SA Pathology, Women and Children’s Hospital, North Adelaide, SA, Australia
| | - Thomas Robertson
- Anatomical Pathology, Queensland Pathology, Brisbane, Queensland, Australia
| | - Pamela McCombe
- Department of Neurology, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia
- Centre for Clinical Research, The University of Queensland Centre for Clinical Research, Brisbane, Queensland, Australia
| | - Nigel G. Laing
- Harry Perkins Institute of Medical Research, Nedlands, WA, Australia
- Centre of Medical Research, University of Western Australia, Nedlands, WA, Australia
- Department of Diagnostic Genomics, PathWest Laboratory Medicine WA, Nedlands, WA, Australia
| | - Liza Phillips
- SA Pathology, Women and Children’s Hospital, North Adelaide, SA, Australia
- The University of Adelaide, Adelaide, SA, Australia
| | - Pascale de Lonlay
- Inserm U1151, Institut Necker Enfants-Malades, Reference Center of Inherited Metabolic Diseases and MetabERN, Necker-Enfants-Malades Hospital, Paris University, Paris, France
| | - Gianina Ravenscroft
- Harry Perkins Institute of Medical Research, Nedlands, WA, Australia
- Centre of Medical Research, University of Western Australia, Nedlands, WA, Australia
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13
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Koch D, Alexandrovich A, Funk F, Kho AL, Schmitt JP, Gautel M. Molecular noise filtering in the β-adrenergic signaling network by phospholamban pentamers. Cell Rep 2021; 36:109448. [PMID: 34320358 PMCID: PMC8333238 DOI: 10.1016/j.celrep.2021.109448] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 04/16/2021] [Accepted: 07/05/2021] [Indexed: 02/07/2023] Open
Abstract
Phospholamban (PLN) is an important regulator of cardiac calcium handling due to its ability to inhibit the calcium ATPase SERCA. β-Adrenergic stimulation reverses SERCA inhibition via PLN phosphorylation and facilitates fast calcium reuptake. PLN also forms pentamers whose physiological significance has remained elusive. Using mathematical modeling combined with biochemical and cell biological experiments, we show that pentamers regulate both the dynamics and steady-state levels of monomer phosphorylation. Substrate competition by pentamers and a feed-forward loop involving inhibitor-1 can delay monomer phosphorylation by protein kinase A (PKA), whereas cooperative pentamer dephosphorylation enables bistable PLN steady-state phosphorylation. Simulations show that phosphorylation delay and bistability act as complementary filters that reduce the effect of random fluctuations in PKA activity, thereby ensuring consistent monomer phosphorylation and SERCA activity despite noisy upstream signals. Preliminary analyses suggest that the PLN mutation R14del could impair noise filtering, offering a new perspective on how this mutation causes cardiac arrhythmias.
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Affiliation(s)
- Daniel Koch
- Randall Centre for Cell and Molecular Biophysics, King's College London, SE1 1UL London, UK.
| | | | - Florian Funk
- Institute of Pharmacology and Clinical Pharmacology, and Cardiovascular Research Institute Düsseldorf (CARID), University Hospital Düsseldorf, 40225 Düsseldorf, Germany
| | - Ay Lin Kho
- Randall Centre for Cell and Molecular Biophysics, King's College London, SE1 1UL London, UK
| | - Joachim P Schmitt
- Institute of Pharmacology and Clinical Pharmacology, and Cardiovascular Research Institute Düsseldorf (CARID), University Hospital Düsseldorf, 40225 Düsseldorf, Germany
| | - Mathias Gautel
- Randall Centre for Cell and Molecular Biophysics, King's College London, SE1 1UL London, UK
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