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Clemens DJ, Ye D, Wang L, Kim CSJ, Zhou W, Dotzler SM, Tester DJ, Marty I, Knollmann BC, Ackerman MJ. Cellular and electrophysiological characterization of triadin knockout syndrome using induced pluripotent stem cell-derived cardiomyocytes. Stem Cell Reports 2023; 18:1075-1089. [PMID: 37163978 PMCID: PMC10202692 DOI: 10.1016/j.stemcr.2023.04.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 04/07/2023] [Accepted: 04/11/2023] [Indexed: 05/12/2023] Open
Abstract
Triadin knockout syndrome (TKOS) is a malignant arrhythmia disorder caused by recessive null variants in TRDN-encoded cardiac triadin. Induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) were generated from two unrelated TKOS patients and an unrelated control. CRISPR-Cas9 gene editing was used to insert homozygous TRDN-p.D18fs∗13 into a control line to generate a TKOS model (TRDN-/-). Western blot confirmed total knockout of triadin in patient-specific and TRDN-/- iPSC-CMs. iPSC-CMs from both patients revealed a prolonged action potential duration (APD) at 90% repolarization, and this was normalized by protein replacement of triadin. APD prolongation was confirmed in TRDN-/- iPSC-CMs. TRDN-/- iPSC-CMs revealed that loss of triadin underlies decreased expression and co-localization of key calcium handling proteins, slow and decreased calcium release from the sarcoplasmic reticulum, and slow inactivation of the L-type calcium channel leading to frequent cellular arrhythmias, including early and delayed afterdepolarizations and APD alternans.
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Affiliation(s)
- Daniel J Clemens
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN, USA
| | - Dan Ye
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN, USA; Department of Cardiovascular Medicine, Division of Heart Rhythm Services, Mayo Clinic, Rochester, MN, USA
| | - Lili Wang
- Department of Medicine, Vanderbilt Center for Arrhythmia Research and Therapeutics, Nashville, TN, USA
| | - C S John Kim
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN, USA; Department of Cardiovascular Medicine, Division of Heart Rhythm Services, Mayo Clinic, Rochester, MN, USA
| | - Wei Zhou
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN, USA; Department of Cardiovascular Medicine, Division of Heart Rhythm Services, Mayo Clinic, Rochester, MN, USA
| | - Steven M Dotzler
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN, USA
| | - David J Tester
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN, USA; Department of Cardiovascular Medicine, Division of Heart Rhythm Services, Mayo Clinic, Rochester, MN, USA
| | - Isabelle Marty
- University Grenoble Alpes, INSERM U1216, CHU Grenoble Alpes, Grenoble Institute Neurosciences, 38000 Grenoble, France
| | - Bjorn C Knollmann
- Department of Medicine, Vanderbilt Center for Arrhythmia Research and Therapeutics, Nashville, TN, USA; Vanderbilt School of Medicine, Nashville, TN, USA
| | - Michael J Ackerman
- Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN, USA; Department of Cardiovascular Medicine, Division of Heart Rhythm Services, Mayo Clinic, Rochester, MN, USA; Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, Rochester, MN, USA.
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Lin DJ, Lee WS, Chien YC, Chen TY, Yang KT. The link between abnormalities of calcium handling proteins and catecholaminergic polymorphic ventricular tachycardia. Tzu Chi Med J 2021; 33:323-331. [PMID: 34760626 PMCID: PMC8532576 DOI: 10.4103/tcmj.tcmj_288_20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 02/09/2021] [Accepted: 03/03/2021] [Indexed: 01/18/2023] Open
Abstract
Catecholaminergic polymorphic ventricular tachycardia (CPVT), a rare autosomal dominant or recessive disease, usually results in syncope or sudden cardiac death. Most CPVT patients do not show abnormal cardiac structure and electrocardiogram features and symptoms, usually onset during adrenergically mediated physiological conditions. CPVT tends to occur at a younger age and is not easy to be diagnosed and managed. The main cause of CPVT is associated with mishandling Ca2+ in cardiomyocytes. Intracellular Ca2+ is strictly controlled by a protein located in the sarcoplasm reticulum (SR), such as ryanodine receptor, histidine-rich Ca2+-binding protein, triadin, and junctin. Mutation in these proteins results in misfolding or malfunction of these proteins, thereby affecting their Ca2+-binding affinity, and subsequently disturbs Ca2+ homeostasis during excitation–contraction coupling (E-C coupling). Furthermore, transient disturbance of Ca2+ homeostasis increases membrane potential and causes Ca2+ store overload-induced Ca2+ release, which in turn leads to delayed after depolarization and arrhythmia. Previous studies have focused on the interaction between ryanodine receptors and protein kinase or phosphatase in the cytosol. However, recent studies showed the regulation signaling for ryanodine receptor not only from the cytosol but also within the SR. The changing of Ca2+ concentration is critical for protein interaction inside the SR which changes protein conformation to regulate the open probability of ryanodine receptors. Thus, it influences the threshold of Ca2+ released from the SR, making it easier to release Ca2+ during E-C coupling. In this review, we briefly discuss how Ca2+ handling protein variations affect the Ca2+ handling in CPVT.
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Affiliation(s)
- Ding-Jyun Lin
- School of Medicine, Tzu Chi University, Hualien, Taiwan
| | - Wen-Sen Lee
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | | | - Tsung-Yu Chen
- School of Medicine, Tzu Chi University, Hualien, Taiwan
| | - Kun-Ta Yang
- Master Program in Medical Physiology, School of Medicine, Tzu Chi University, Hualien, Taiwan.,Department of Physiology, School of Medicine, Tzu Chi University, Hualien, Taiwan
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Ogasawara M, Ogawa M, Nonaka I, Hayashi S, Noguchi S, Nishino I. Evaluation of the Core Formation Process in Congenital Neuromuscular Disease With Uniform Type 1 Fiber and Central Core Disease. J Neuropathol Exp Neurol 2021; 79:1370-1375. [PMID: 33184643 DOI: 10.1093/jnen/nlaa104] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Typical central core disease (CCD) is characterized pathologically by the presence of a core and is accompanied by type 1 fiber uniformity. Congenital neuromuscular disease with uniform type 1 fiber (CNMDU1) is characterized pathologically by the presence of type 1 fiber uniformity but without the abnormal structural changes in muscle fibers. Interestingly, typical CCD and 40% of CNMDU1 cases are caused by the same mutations in RYR1, and thus CNMDU1 has been considered an early precursor to CCD. To better understand the nature of CNMDU1, we re-evaluated muscle biopsies from 16 patients with CNMDU1 using immunohistochemistry to RYR1, triadin and TOM20, and compared this to muscle biopsies from 36 typical CCD patients. In CCD, RYR1, and triadin were present in the core regions, while TOM20 was absent in the core regions. Interestingly, in 5 CNMDU1 cases with the RYR1 mutation, RYR1, and triadin were similarly present in core-like areas, while TOM20 was absent in the subsarcolemmal region. Furthermore, there was a correlation between the core position and the disease duration or progression-the older patients in more advanced stages had more centralized cores. Our results indicate that CNMDU1 due to RYR1 mutation is a de facto core myopathy.
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Affiliation(s)
- Masashi Ogasawara
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), Kodaira, Tokyo, Japan.,Department of Genome Medicine Development, Medical Genome Center, NCNP, Kodaira, Japan.,Institute of Medical Genetics, Tokyo Women's Medical University, Tokyo, Japan
| | - Megumu Ogawa
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), Kodaira, Tokyo, Japan
| | - Ikuya Nonaka
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), Kodaira, Tokyo, Japan.,Department of Genome Medicine Development, Medical Genome Center, NCNP, Kodaira, Japan
| | - Shinichiro Hayashi
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), Kodaira, Tokyo, Japan.,Department of Genome Medicine Development, Medical Genome Center, NCNP, Kodaira, Japan
| | - Satoru Noguchi
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), Kodaira, Tokyo, Japan.,Department of Genome Medicine Development, Medical Genome Center, NCNP, Kodaira, Japan
| | - Ichizo Nishino
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), Kodaira, Tokyo, Japan.,Department of Genome Medicine Development, Medical Genome Center, NCNP, Kodaira, Japan
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Clemens DJ, Tester DJ, Marty I, Ackerman MJ. Phenotype-guided whole genome analysis in a patient with genetically elusive long QT syndrome yields a novel TRDN-encoded triadin pathogenetic substrate for triadin knockout syndrome and reveals a novel primate-specific cardiac TRDN transcript. Heart Rhythm 2020; 17:1017-24. [PMID: 32402482 DOI: 10.1016/j.hrthm.2020.01.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 01/14/2020] [Indexed: 12/11/2022]
Abstract
BACKGROUND Triadin knockout syndrome (TKOS) is a rare arrhythmia syndrome caused by recessive null variants in TRDN-encoded cardiac triadin 1. TKOS has presented frequently with cardiac arrest in childhood. OBJECTIVE The purpose of this study was to elucidate the underlying genetic mechanism of disease in a genetically elusive patient displaying a characteristic TKOS phenotype. METHODS Genome sequencing and a TRDN gene-specific trio analysis were completed on the patient. RNA and protein isolated from patient-specific human-induced pluripotent stem cell-derived cardiomyocytes were used to determine the effects of the identified variants using reverse transcription polymerase chain reaction (RT-PCR) and Western blot. RESULTS Genome sequencing revealed compound heterozygous putative splice-error variants (maternal c.22+29A>G and paternal c.484+1189G>A). The novel paternally derived c.484+1189G>A variant is located within 24 base pairs of a predicted alternative exon 6 (exon 6a), which resides within the intron between canonical exons 5 and 6. We determined that this previously unrecognized exon 6a produces a short TRDN transcript and potentially a novel protein isoform in the normal human heart. The c.484+1189G>A variant not only results in abnormal splicing of the exon 6a-containing transcript leading to a frameshift mutation but also results in the abolishment of the 8-exon cardiac triadin 1 transcript. CONCLUSION Here, we present evidence for a novel alternative exon 6a-containing TRDN transcript in the normal heart. The novel deep intronic TRDN variant identified in a patient with TKOS leads to splicing error of a newly recognized exon 6a and loss of triadin. Considering that both TRDN variants in this patient were missed after commercial testing, these results highlight the importance of using genome sequencing when identifying patients with TKOS.
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Rossi D, Gigli L, Gamberucci A, Bordoni R, Pietrelli A, Lorenzini S, Pierantozzi E, Peretto G, De Bellis G, Della Bella P, Ferrari M, Sorrentino V, Benedetti S, Sala S, Di Resta C. A novel homozygous mutation in the TRDN gene causes a severe form of pediatric malignant ventricular arrhythmia. Heart Rhythm 2019; 17:296-304. [PMID: 31437535 DOI: 10.1016/j.hrthm.2019.08.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Indexed: 12/26/2022]
Abstract
BACKGROUND Triadin is a protein expressed in cardiac and skeletal muscle that has an essential role in the structure and functional regulation of calcium release units and excitation-contraction coupling. Mutations in the triadin gene (TRDN) have been described in different forms of human arrhythmia syndromes with early onset and severe arrhythmogenic phenotype, including triadin knockout syndrome. OBJECTIVE The purpose of this study was to characterize the pathogenetic mechanism underlying a case of severe pediatric malignant arrhythmia associated with a defect in the TRDN gene. METHODS We used a trio whole exome sequencing approach to identify the genetic defect in a 2-year-old boy who had been resuscitated from sudden cardiac arrest and had frequent episodes of ventricular fibrillation and a family history positive for sudden death. We then performed in vitro functional analysis to investigate possible pathogenic mechanisms underlying this severe phenotype. RESULTS We identified a novel homozygous missense variant (p.L56P) in the TRDN gene in the proband that was inherited from the heterozygous unaffected parents. Expression of a green fluorescent protein (GFP)-tagged mutant human cardiac triadin isoform (TRISK32-L56P-GFP) in heterologous systems revealed that the mutation alters protein dynamics. Furthermore, when co-expressed with the type 2 ryanodine receptor, caffeine-induced calcium release from TRISK32-L56P-GFP was relatively lower compared to that observed with the wild-type construct. CONCLUSION The results of this study allowed us to hypothesize a pathogenic mechanism underlying this rare arrhythmogenic recessive form, suggesting that the mutant protein potentially can trigger arrhythmias by altering calcium homeostasis.
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Affiliation(s)
- Daniela Rossi
- Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
| | - Lorenzo Gigli
- Department of Arrhythmology, IRCCS San Raffaele Hospital, Milan, Italy
| | - Alessandra Gamberucci
- Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
| | - Roberta Bordoni
- Institute of Biomedical Technologies, National Research Council of Italy, Milan, Italy
| | - Alessandro Pietrelli
- Institute of Biomedical Technologies, National Research Council of Italy, Milan, Italy
| | - Stefania Lorenzini
- Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
| | - Enrico Pierantozzi
- Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
| | - Giovanni Peretto
- Department of Arrhythmology, IRCCS San Raffaele Hospital, Milan, Italy
| | - Gianluca De Bellis
- Institute of Biomedical Technologies, National Research Council of Italy, Milan, Italy
| | - Paolo Della Bella
- Department of Arrhythmology, IRCCS San Raffaele Hospital, Milan, Italy
| | - Maurizio Ferrari
- Vita-Salute San Raffaele University, Milan, Italy; Laboratory of Clinical Molecular Biology and Cytogenetics, IRCCS San Raffaele Hospital, Milan, Italy; Genomic Unit for the Diagnosis of Human Pathologies, Division of Genetics and Cellular Biology, IRCCS San Raffaele Hospital, Milan, Italy
| | - Vincenzo Sorrentino
- Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
| | - Sara Benedetti
- Laboratory of Clinical Molecular Biology and Cytogenetics, IRCCS San Raffaele Hospital, Milan, Italy
| | - Simone Sala
- Department of Arrhythmology, IRCCS San Raffaele Hospital, Milan, Italy
| | - Chiara Di Resta
- Vita-Salute San Raffaele University, Milan, Italy; Genomic Unit for the Diagnosis of Human Pathologies, Division of Genetics and Cellular Biology, IRCCS San Raffaele Hospital, Milan, Italy.
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O’Callaghan BM, Hancox JC, Stuart AG, Armstrong C, Williams MM, Hills A, Pearce H, Dent CL, Gable M, Walsh MA. A unique triadin exon deletion causing a null phenotype. HeartRhythm Case Rep 2018; 4:514-518. [PMID: 30479949 PMCID: PMC6241331 DOI: 10.1016/j.hrcr.2018.07.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
| | - Jules C. Hancox
- School of Physiology and Pharmacology, Cardiovascular Research Laboratories, University of Bristol, Bristol, United Kingdom
| | - Alan G. Stuart
- Bristol Royal Hospital for Children, Bristol, United Kingdom
| | | | - Maggie M. Williams
- Genomic Diagnostics Laboratory, University Hospital Bristol, Bristol, United Kingdom
| | - Alison Hills
- Genomic Diagnostics Laboratory, University Hospital Bristol, Bristol, United Kingdom
| | - Hazel Pearce
- Genomic Diagnostics Laboratory, University Hospital Bristol, Bristol, United Kingdom
| | - Carolyn L. Dent
- Genomic Diagnostics Laboratory, University Hospital Bristol, Bristol, United Kingdom
| | - Mary Gable
- Genomic Diagnostics Laboratory, University Hospital Bristol, Bristol, United Kingdom
| | - Mark A. Walsh
- Bristol Royal Hospital for Children, Bristol, United Kingdom
- Address reprint requests and correspondence: Dr Mark A. Walsh, Our Lady's Children's Hospital, Crumlin, Cooley Road, Drimnagh, Dublin, Ireland.
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Zhang L, Salgado-Somoza A, Vausort M, Leszek P, Devaux Y. A heart-enriched antisense long non-coding RNA regulates the balance between cardiac and skeletal muscle triadin. Biochim Biophys Acta Mol Cell Res 2017; 1865:247-258. [PMID: 29126880 DOI: 10.1016/j.bbamcr.2017.11.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 11/02/2017] [Accepted: 11/03/2017] [Indexed: 12/20/2022]
Abstract
Non-coding RNAs play major roles in cardiac pathophysiology. Recent studies reported that long non-coding RNAs (lncRNAs) are dysregulated in the failing heart, but how they contribute to heart failure development is unclear. In this study, we aimed to identify heart-enriched lncRNAs and investigate their regulation and function in the failing heart. RESULTS Analysis of a RNA-seq dataset of 15 Caucasian tissues allowed the identification of 415 heart-enriched lncRNAs. Fifty-three lncRNAs were located on the genome in close vicinity to protein-coding genes associated with cardiac function and disease. Analysis of a second RNA-seq dataset of 16 failing human hearts highlighted one lncRNA which we arbitrarily named TRDN-AS due to its localisation in the antisense position of the gene encoding triadin (TRDN). Expression of TRDN-AS and cardiac TRDN was up-regulated in biopsies from failing human hearts compared to control hearts. In failing hearts, TRDN-AS was positively correlated with a cardiac isoform of TRDN and negatively correlated with a skeletal muscle isoform of TRDN. A murine homolog of human TRDN-AS was identified and found to be enriched in the heart and localised in the nuclear compartment of cardiomyocytes. Trdn-AS expression as well as the ratio between cardiac and skeletal muscle isoforms were down-regulated after experimental myocardial infarction. In murine cardiomyocytes, activation of Trdn-AS transcription with the CRISPR/dCas9-VPR system enhanced the ratio between cardiac and skeletal isoforms of Trdn. CONCLUSION The lncRNA TRDN-AS regulates the balance between cardiac and skeletal isoforms of triadin. This finding may have implications for the treatment of heart failure.
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Affiliation(s)
- Lu Zhang
- Cardiovascular Research Unit, Luxembourg Health Institute, Luxembourg
| | | | - Melanie Vausort
- Cardiovascular Research Unit, Luxembourg Health Institute, Luxembourg
| | - Przemyslaw Leszek
- Heart Failure and Transplantology Department, Institute of Cardiology, Warsaw, Poland
| | - Yvan Devaux
- Cardiovascular Research Unit, Luxembourg Health Institute, Luxembourg.
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Wium E, Dulhunty AF, Beard NA. Three residues in the luminal domain of triadin impact on Trisk 95 activation of skeletal muscle ryanodine receptors. Pflugers Arch 2016; 468:1985-94. [PMID: 27595738 DOI: 10.1007/s00424-016-1869-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Revised: 08/02/2016] [Accepted: 08/11/2016] [Indexed: 10/21/2022]
Abstract
Triadin isoforms, splice variants of one gene, maintain healthy Ca2+ homeostasis in skeletal muscle by subserving several functions including an influence on Ca2+ release through the ligand-gated ryanodine receptor (RyR1) ion channels. The predominant triadin isoform in skeletal muscle, Trisk 95, activates RyR1 in vitro via binding to previously unidentified amino acids between residues 200 and 232. Here, we identify three amino acids that influence Trisk 95 binding to RyR1 and ion channel activation, using peptides encompassing residues 200-232. Selective alanine substitutions show that K218, K220, and K224 together facilitate normal Trisk 95 binding to RyR1 and channel activation. Neither RyR1 binding nor activation are altered by alanine substitution of K220 alone or of K218 and K224. Therefore K218, K220, and K224 contribute to a robust binding and activation site that is disrupted only when the charge on all three residues is neutralized. We suggest that charged pair interactions between acidic RyR1 residues D4878, D4907, and E4908 and Trisk 95 residues K218, K220, and K224 facilitate Trisk 95 binding to RyR1 and channel activation. Since K218, K220, and K224 are also required for CSQ binding to RyRs (Kobayashi et al. 17, J Biol Chem 275, 17639-17646), the results suggest that Trisk 95 may not simultaneously bind to RyR1 and CSQ, contrary to the widely held belief that triadin monomers form a quaternary complex with junctin, CSQ and RyR1. Therefore, the in vivo role of triadin monomers in modulating RyR1 activity is likely unrelated to CSQ.
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Osseni A, Sébastien M, Sarrault O, Baudet M, Couté Y, Fauré J, Fourest-Lieuvin A, Marty I. Triadin and CLIMP-63 form a link between triads and microtubules in muscle cells. J Cell Sci 2016; 129:3744-3755. [PMID: 27562070 DOI: 10.1242/jcs.188862] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 08/18/2016] [Indexed: 01/20/2023] Open
Abstract
In skeletal muscle, the triad is a structure comprising a transverse (T)-tubule and sarcoplasmic reticulum (SR) cisternae. Triads constitute the basis of excitation-contraction coupling as the cradle of the Ca2+ release complex. We have shown previously that triadin, a member of this complex, has shaping properties on reticulum membrane and is indirectly involved in a link between triads and microtubules. We have identified here that CLIMP-63 (also known as CKAP4), as the partner of triadin, is responsible for this association of triads and microtubules. Triadin and CLIMP-63 interact through their respective luminal domains and the shaping properties of triadin depend on the capacity of CLIMP-63 to bind microtubules with its cytosolic portion. In skeletal muscle, CLIMP-63 is localized in the SR, including triads, and is associated with the Ca2+ release complex through its interaction with triadin. Knockout of triadin in muscles results in the delocalization of CLIMP-63 from triads, its dissociation from the Ca2+ release complex and a disorganization of the microtubule network. Our results suggest that the association of triadin and CLIMP-63 could be involved in the shaping of SR terminal cisternae and in the guidance of microtubules close to the triads.
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Affiliation(s)
- Alexis Osseni
- University Grenoble Alpes, Grenoble Institut des Neurosciences, GIN, Grenoble F-38000, France INSERM, U1216, Grenoble F-38000, France
| | - Muriel Sébastien
- University Grenoble Alpes, Grenoble Institut des Neurosciences, GIN, Grenoble F-38000, France INSERM, U1216, Grenoble F-38000, France
| | - Oriana Sarrault
- University Grenoble Alpes, Grenoble Institut des Neurosciences, GIN, Grenoble F-38000, France INSERM, U1216, Grenoble F-38000, France
| | - Mathieu Baudet
- University Grenoble Alpes, BIG-BGE, Grenoble F-38000, France CEA, BIG, BGE and GPC, Grenoble F-38000, France INSERM, BGE, Grenoble F-38000, France
| | - Yohann Couté
- University Grenoble Alpes, BIG-BGE, Grenoble F-38000, France CEA, BIG, BGE and GPC, Grenoble F-38000, France INSERM, BGE, Grenoble F-38000, France
| | - Julien Fauré
- University Grenoble Alpes, Grenoble Institut des Neurosciences, GIN, Grenoble F-38000, France INSERM, U1216, Grenoble F-38000, France CHU de Grenoble, Grenoble F-38000, France
| | - Anne Fourest-Lieuvin
- University Grenoble Alpes, Grenoble Institut des Neurosciences, GIN, Grenoble F-38000, France INSERM, U1216, Grenoble F-38000, France CEA, BIG, BGE and GPC, Grenoble F-38000, France
| | - Isabelle Marty
- University Grenoble Alpes, Grenoble Institut des Neurosciences, GIN, Grenoble F-38000, France INSERM, U1216, Grenoble F-38000, France
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Sleiman NH, McFarland TP, Jones LR, Cala SE. Transitions of protein traffic from cardiac ER to junctional SR. J Mol Cell Cardiol 2015; 81:34-45. [PMID: 25640161 DOI: 10.1016/j.yjmcc.2014.12.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 12/29/2014] [Accepted: 12/29/2014] [Indexed: 11/20/2022]
Abstract
The junctional sarcoplasmic reticulum (jSR) is an important and unique ER subdomain in the adult myocyte that concentrates resident proteins to regulate Ca(2+) release. To investigate cellular mechanisms for sorting and trafficking proteins to jSR, we overexpressed canine forms of junctin (JCT) or triadin (TRD) in adult rat cardiomyocytes. Protein accumulation over time was visualized by confocal fluorescence microscopy using species-specific antibodies. Newly synthesized JCTdog and TRDdog appeared by 12-24h as bright fluorescent puncta close to the nuclear surface, decreasing in intensity with increasing radial distance. With increasing time (24-48h), fluorescent puncta appeared at further radial distances from the nuclear surface, eventually populating jSR similar to steady-state patterns. CSQ2-DsRed, a form of CSQ that polymerizes ectopically in rough ER, prevented anterograde traffic of newly made TRDdog and JCTdog, demonstrating common pathways of intracellular trafficking as well as in situ binding to CSQ2 in juxtanuclear rough ER. Reversal of CSQ-DsRed interactions occurred when a form of TRDdog was used in which CSQ2-binding sites are removed ((del)TRD). With increasing levels of expression, CSQ2-DsRed revealed a novel smooth ER network that surrounds nuclei and connects the nuclear axis. TRDdog was retained in smooth ER by binding to CSQ2-DsRed, but escaped to populate jSR puncta. TRDdog and (del)TRD were therefore able to elucidate areas of ER-SR transition. High levels of CSQ2-DsRed in the ER led to loss of jSR puncta labeling, suggesting a plasticity of ER-SR transition sites. We propose a model of ER and SR protein traffic along microtubules, with prominent transverse/radial ER trafficking of JCT and TRD along Z-lines to populate jSR, and an abundant longitudinal/axial smooth ER between and encircling myonuclei, from which jSR proteins traffic.
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