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Douglas CM, Bird JE, Kopinke D, Esser KA. An optimized approach to study nanoscale sarcomere structure utilizing super-resolution microscopy with nanobodies. PLoS One 2024; 19:e0300348. [PMID: 38687705 PMCID: PMC11060602 DOI: 10.1371/journal.pone.0300348] [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: 11/06/2023] [Accepted: 02/23/2024] [Indexed: 05/02/2024] Open
Abstract
The sarcomere is the fundamental contractile unit in skeletal muscle, and the regularity of its structure is critical for function. Emerging data demonstrates that nanoscale changes to the regularity of sarcomere structure can affect the overall function of the protein dense ~2μm sarcomere. Further, sarcomere structure is implicated in many clinical conditions of muscle weakness. However, our understanding of how sarcomere structure changes in disease, especially at the nanoscale, has been limited in part due to the inability to robustly detect and measure at sub-sarcomere resolution. We optimized several methodological steps and developed a robust pipeline to analyze sarcomere structure using structured illumination super-resolution microscopy in conjunction with commercially-available and fluorescently-conjugated Variable Heavy-Chain only fragment secondary antibodies (nanobodies), and achieved a significant increase in resolution of z-disc width (353nm vs. 62nm) compared to confocal microscopy. The combination of these methods provides a unique approach to probe sarcomere protein localization at the nanoscale and may prove advantageous for analysis of other cellular structures.
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Affiliation(s)
- Collin M. Douglas
- Department of Physiology and Aging, University of Florida, Gainesville, Florida, United States of America
| | - Jonathan E. Bird
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, Florida, United States of America
| | - Daniel Kopinke
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, Florida, United States of America
| | - Karyn A. Esser
- Department of Physiology and Aging, University of Florida, Gainesville, Florida, United States of America
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2
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Lopez MA, Pardo PS, Mohamed JS, Boriek AM. ANKRD1 expression is aberrantly upregulated in the mdm mouse model of muscular dystrophy and induced by stretch through NFκB. J Muscle Res Cell Motil 2024:10.1007/s10974-024-09671-x. [PMID: 38683293 DOI: 10.1007/s10974-024-09671-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 03/22/2024] [Indexed: 05/01/2024]
Abstract
The muscular dystrophy with myositis (mdm) mouse model results in a severe muscular dystrophy due to an 83-amino-acid deletion in the N2A region of titin, an expanded sarcomeric protein that functions as a molecular spring which senses and modulates the response to mechanical forces in cardiac and skeletal muscles. ANKRD1 is one of the muscle ankyrin repeat domain proteins (MARPs) a family of titin-associated, stress-response molecules and putative transducers of stretch-induced signaling in skeletal muscle. The aberrant over-activation of Nuclear factor Kappa B (NF-κB) and the Ankyrin-repeat domain containing protein 1 (ANKRD1) occurs in several models of progressive muscle disease including Duchenne muscular dystrophy. We hypothesized that mechanical regulation of ANKRD1 is mediated by NF-κB activation in skeletal muscles and that this mechanism is perturbed by small deletion of the stretch-sensing titin N2A region in the mdm mouse. We applied static mechanical stretch of the mdm mouse diaphragm and cyclic mechanical stretch of C2C12 myotubes to examine the interaction between NF-κΒ and ANKRD1 expression utilizing Western blot and qRTPCR. As seen in skeletal muscles of other severe muscular dystrophies, an aberrant increased basal expression of NF-κB and ANKRD1 were observed in the diaphragm muscles of the mdm mice. Our data show that in the mdm diaphragm, basal levels of NF-κB are increased, and pharmacological inhibition of NF-κB does not alter basal levels of ANKRD1. Alternatively, NF-κB inhibition did alter stretch-induced ANKRD1 upregulation. These data show that NF-κB activity is at least partially responsible for the stretch-induced expression of ANKRD1.
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Affiliation(s)
- Michael A Lopez
- Departments of Medicine and Molecular Physiology and Biophysics, Baylor College of Medicine, Suite 523-D2, Houston, TX, 77030, USA
- Department of Pediatrics, University of Alabama at Birmingham, Birmingham, AL, 35233, USA
| | - Patricia S Pardo
- Departments of Medicine and Molecular Physiology and Biophysics, Baylor College of Medicine, Suite 523-D2, Houston, TX, 77030, USA
| | - Junaith S Mohamed
- Departments of Medicine and Molecular Physiology and Biophysics, Baylor College of Medicine, Suite 523-D2, Houston, TX, 77030, USA
- Laboratory of Muscle and Nerve, Department of Diagnostic and Helath Sciences, College of Health Professions, University of Tennessee Health Science Center, Memphis, TN, 38163, USA
| | - Aladin M Boriek
- Departments of Medicine and Molecular Physiology and Biophysics, Baylor College of Medicine, Suite 523-D2, Houston, TX, 77030, USA.
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3
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Korb A, Tajbakhsh S, Comai GE. Functional specialisation and coordination of myonuclei. Biol Rev Camb Philos Soc 2024. [PMID: 38477382 DOI: 10.1111/brv.13063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 01/30/2024] [Accepted: 02/02/2024] [Indexed: 03/14/2024]
Abstract
Myofibres serve as the functional unit for locomotion, with the sarcomere as fundamental subunit. Running the entire length of this structure are hundreds of myonuclei, located at the periphery of the myofibre, juxtaposed to the plasma membrane. Myonuclear specialisation and clustering at the centre and ends of the fibre are known to be essential for muscle contraction, yet the molecular basis of this regionalisation has remained unclear. While the 'myonuclear domain hypothesis' helped explain how myonuclei can independently govern large cytoplasmic territories, novel technologies have provided granularity on the diverse transcriptional programs running simultaneously within the syncytia and added a new perspective on how myonuclei communicate. Building upon this, we explore the critical cellular and molecular sources of transcriptional and functional heterogeneity within myofibres, discussing the impact of intrinsic and extrinsic factors on myonuclear programs. This knowledge provides new insights for understanding muscle development, repair, and disease, but also opens avenues for the development of novel and precise therapeutic approaches.
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Affiliation(s)
- Amaury Korb
- Institut Pasteur, Université Paris Cité, CNRS UMR 3738, Stem Cells & Development Unit, 25 rue du Dr. Roux, Institut Pasteur, Paris, F-75015, France
| | - Shahragim Tajbakhsh
- Institut Pasteur, Université Paris Cité, CNRS UMR 3738, Stem Cells & Development Unit, 25 rue du Dr. Roux, Institut Pasteur, Paris, F-75015, France
| | - Glenda E Comai
- Institut Pasteur, Université Paris Cité, CNRS UMR 3738, Stem Cells & Development Unit, 25 rue du Dr. Roux, Institut Pasteur, Paris, F-75015, France
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4
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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.
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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
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Vermersch E, Neuvendel S, Jouve C, Ruiz-Velasco A, Pereira C, Seguret M, Cattin-Messaoudi ME, Lotfi S, Dorval T, Berson P, Hulot JS. hsa-miR-548v controls the viscoelastic properties of human cardiomyocytes and improves their relaxation rates. JCI Insight 2024; 9:e161356. [PMID: 38165745 PMCID: PMC11143964 DOI: 10.1172/jci.insight.161356] [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: 04/25/2022] [Accepted: 12/19/2023] [Indexed: 01/04/2024] Open
Abstract
The impairment of left ventricular (LV) diastolic function with an inadequate increase in myocardial relaxation velocity directly results in lower LV compliance, increased LV filling pressures, and heart failure symptoms. The development of agents facilitating the relaxation of human cardiomyocytes requires a better understanding of the underlying regulatory mechanisms. We performed a high-content microscopy-based screening in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) using a library of 2,565 human miRNA mimics and measured relaxation kinetics via high-computing analyses of motion movies. We identified hsa-miR-548v, a primate-specific miRNA, as the miRNA producing the largest increase in relaxation velocities. This positive lusitropic effect was reproduced in engineered cardiac tissues generated with healthy and BRAF T599R mutant hiPSC-CMs and was independent of changes in calcium transients. Consistent with improvements in viscoelastic responses to mechanical stretch, RNA-Seq showed that hsa-miR-548v downregulated multiple targets, especially components of the mechanosensing machinery. The exogenous administration of hsa-miR-548v in hiPSC-CMs notably resulted in a significant reduction of ANKRD1/CARP1 expression and localization at the sarcomeric I-band. This study suggests that the sarcomere I-band is a critical control center regulating the ability of cardiomyocytes to relax and is a target for improving relaxation and diastolic dysfunction.
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Affiliation(s)
- Eva Vermersch
- Université Paris Cité, Inserm, PARCC, F-75015 Paris, France
- Institut de recherches Servier, In vitro Pharmacology unit, and
| | | | - Charlène Jouve
- Université Paris Cité, Inserm, PARCC, F-75015 Paris, France
| | | | - Céline Pereira
- Université Paris Cité, Inserm, PARCC, F-75015 Paris, France
| | - Magali Seguret
- Université Paris Cité, Inserm, PARCC, F-75015 Paris, France
| | | | - Sofia Lotfi
- Institut de recherches Servier, In vitro Pharmacology unit, and
| | - Thierry Dorval
- Institut de recherches Servier, In vitro Pharmacology unit, and
| | - Pascal Berson
- Institut de recherches Servier, Cardiovascular and Metabolism Therapeutic Area, Croissy-sur-seine, France
| | - Jean-Sébastien Hulot
- Université Paris Cité, Inserm, PARCC, F-75015 Paris, France
- CIC1418 and DMU CARTE, AP-HP, Hôpital Européen Georges-Pompidou, F-75015, Paris, France
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Pass CG, Palzkill V, Tan J, Kim K, Thome T, Yang Q, Fazzone B, Robinson ST, O’Malley KA, Yue F, Scali ST, Berceli SA, Ryan TE. Single-Nuclei RNA-Sequencing of the Gastrocnemius Muscle in Peripheral Artery Disease. Circ Res 2023; 133:791-809. [PMID: 37823262 PMCID: PMC10599805 DOI: 10.1161/circresaha.123.323161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 09/22/2023] [Accepted: 09/26/2023] [Indexed: 10/13/2023]
Abstract
BACKGROUND Lower extremity peripheral artery disease (PAD) is a growing epidemic with limited effective treatment options. Here, we provide a single-nuclei atlas of PAD limb muscle to facilitate a better understanding of the composition of cells and transcriptional differences that comprise the diseased limb muscle. METHODS We obtained gastrocnemius muscle specimens from 20 patients with PAD and 12 non-PAD controls. Nuclei were isolated and single-nuclei RNA-sequencing was performed. The composition of nuclei was characterized by iterative clustering via principal component analysis, differential expression analysis, and the use of known marker genes. Bioinformatics analysis was performed to determine differences in gene expression between PAD and non-PAD nuclei, as well as subsequent analysis of intercellular signaling networks. Additional histological analyses of muscle specimens accompany the single-nuclei RNA-sequencing atlas. RESULTS Single-nuclei RNA-sequencing analysis indicated a fiber type shift with patients with PAD having fewer type I (slow/oxidative) and more type II (fast/glycolytic) myonuclei compared with non-PAD, which was confirmed using immunostaining of muscle specimens. Myonuclei from PAD displayed global upregulation of genes involved in stress response, autophagy, hypoxia, and atrophy. Subclustering of myonuclei also identified populations that were unique to PAD muscle characterized by metabolic dysregulation. PAD muscles also displayed unique transcriptional profiles and increased diversity of transcriptomes in muscle stem cells, regenerating myonuclei, and fibro-adipogenic progenitor cells. Analysis of intercellular communication networks revealed fibro-adipogenic progenitors as a major signaling hub in PAD muscle, as well as deficiencies in angiogenic and bone morphogenetic protein signaling which may contribute to poor limb function in PAD. CONCLUSIONS This reference single-nuclei RNA-sequencing atlas provides a comprehensive analysis of the cell composition, transcriptional signature, and intercellular communication pathways that are altered in the PAD condition.
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Affiliation(s)
- Caroline G. Pass
- Department of Applied Physiology and Kinesiology (C.G.P., V.P., J.T., K.K., T.T., Q.Y., T.E.R.), The University of Florida, Gainesville
| | - Victoria Palzkill
- Department of Applied Physiology and Kinesiology (C.G.P., V.P., J.T., K.K., T.T., Q.Y., T.E.R.), The University of Florida, Gainesville
| | - Jianna Tan
- Department of Applied Physiology and Kinesiology (C.G.P., V.P., J.T., K.K., T.T., Q.Y., T.E.R.), The University of Florida, Gainesville
| | - Kyoungrae Kim
- Department of Applied Physiology and Kinesiology (C.G.P., V.P., J.T., K.K., T.T., Q.Y., T.E.R.), The University of Florida, Gainesville
| | - Trace Thome
- Department of Applied Physiology and Kinesiology (C.G.P., V.P., J.T., K.K., T.T., Q.Y., T.E.R.), The University of Florida, Gainesville
| | - Qingping Yang
- Department of Applied Physiology and Kinesiology (C.G.P., V.P., J.T., K.K., T.T., Q.Y., T.E.R.), The University of Florida, Gainesville
| | - Brian Fazzone
- Department of Surgery, Division of Vascular Surgery and Endovascular Therapy (B.F., S.T.R., K.A.O., S.T.S., S.A.B.), The University of Florida, Gainesville
- Malcom Randall VA Medical Center, Gainesville, FL (B.F., S.T.R., K.A.O., S.T.S., S.A.B.)
| | - Scott T. Robinson
- Department of Surgery, Division of Vascular Surgery and Endovascular Therapy (B.F., S.T.R., K.A.O., S.T.S., S.A.B.), The University of Florida, Gainesville
- Malcom Randall VA Medical Center, Gainesville, FL (B.F., S.T.R., K.A.O., S.T.S., S.A.B.)
| | - Kerri A. O’Malley
- Department of Surgery, Division of Vascular Surgery and Endovascular Therapy (B.F., S.T.R., K.A.O., S.T.S., S.A.B.), The University of Florida, Gainesville
- Malcom Randall VA Medical Center, Gainesville, FL (B.F., S.T.R., K.A.O., S.T.S., S.A.B.)
| | - Feng Yue
- Department of Animal Sciences (F.Y.), The University of Florida, Gainesville
- Myology Institute (F.Y., T.E.R.), The University of Florida, Gainesville
| | - Salvatore T. Scali
- Department of Surgery, Division of Vascular Surgery and Endovascular Therapy (B.F., S.T.R., K.A.O., S.T.S., S.A.B.), The University of Florida, Gainesville
- Malcom Randall VA Medical Center, Gainesville, FL (B.F., S.T.R., K.A.O., S.T.S., S.A.B.)
| | - Scott A. Berceli
- Department of Surgery, Division of Vascular Surgery and Endovascular Therapy (B.F., S.T.R., K.A.O., S.T.S., S.A.B.), The University of Florida, Gainesville
- Malcom Randall VA Medical Center, Gainesville, FL (B.F., S.T.R., K.A.O., S.T.S., S.A.B.)
| | - Terence E. Ryan
- Department of Applied Physiology and Kinesiology (C.G.P., V.P., J.T., K.K., T.T., Q.Y., T.E.R.), The University of Florida, Gainesville
- Center for Exercise Science (T.E.R.), The University of Florida, Gainesville
- Myology Institute (F.Y., T.E.R.), The University of Florida, Gainesville
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7
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Stehle J, Fleming JR, Bauer PM, Mayans O, Drescher M. Titin UN2A Acts as a Stable, Non-Polymorphic Scaffold in its Binding to CARP. Chembiochem 2023; 24:e202300408. [PMID: 37503755 DOI: 10.1002/cbic.202300408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 07/25/2023] [Accepted: 07/27/2023] [Indexed: 07/29/2023]
Abstract
The N2A segment of titin functions as a pivotal hub for signal transduction and interacts with various proteins involved in structural support, chaperone activities, and transcriptional regulation. Notably, the "unique N2A" (UN2A) subdomain has been shown to interact with the stress-regulated cardiac ankyrin repeat protein (CARP), which contributes to the regulation of sarcomeric stiffness. Previously, the UN2A domain's three-dimensional structure was modelled based on its secondary structure content identified by NMR spectroscopy, considering the domain in isolation. In this study, we report experimental long-range distance distributions by electron paramagnetic resonance (EPR) spectroscopy between the three helixes within the UN2A domain linked to the immunoglobulin domain I81 in the presence and absence of CARP. The data confirm the central three-helix bundle fold of UN2A and show that this adopts a compact and stable conformation in absence of CARP. After binding to CARP, no significant conformational change was observed, suggesting that the UN2A domain retains its structure upon binding to CARP thereby, mediating the interaction approximately as a rigid-body.
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Affiliation(s)
- Juliane Stehle
- Department of Chemistry and Konstanz Research School of Chemical Biology (KoRS-CB), University of Konstanz, Universitätsstraße 10, 78457, Konstanz, Germany
| | - Jennifer R Fleming
- Department of Biology, University of Konstanz, Universitätsstraße 10, 78457, Konstanz, Germany
| | - Piera-Maria Bauer
- Department of Biology, University of Konstanz, Universitätsstraße 10, 78457, Konstanz, Germany
| | - Olga Mayans
- Department of Biology, University of Konstanz, Universitätsstraße 10, 78457, Konstanz, Germany
| | - Malte Drescher
- Department of Chemistry and Konstanz Research School of Chemical Biology (KoRS-CB), University of Konstanz, Universitätsstraße 10, 78457, Konstanz, Germany
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8
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Linke WA. Stretching the story of titin and muscle function. J Biomech 2023; 152:111553. [PMID: 36989971 DOI: 10.1016/j.jbiomech.2023.111553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 03/14/2023] [Indexed: 03/29/2023]
Abstract
The discovery of the giant protein titin, also known as connectin, dates almost half a century back. In this review, I recapitulate major advances in the discovery of the titin filaments and the recognition of their properties and function until today. I briefly discuss how our understanding of the layout and interactions of titin in muscle sarcomeres has evolved and review key facts about the titin sequence at the gene (TTN) and protein levels. I also touch upon properties of titin important for the stability of the contractile units and the assembly and maintenance of sarcomeric proteins. The greater part of my discussion centers around the mechanical function of titin in skeletal muscle. I cover milestones of research on titin's role in stretch-dependent passive tension development, recollect the reasons behind the enormous elastic diversity of titin, and provide an update on the molecular mechanisms of titin elasticity, details of which are emerging even now. I reflect on current knowledge of how muscle fibers behave mechanically if titin stiffness is removed and how titin stiffness can be dynamically regulated, such as by posttranslational modifications or calcium binding. Finally, I highlight novel and exciting, but still controversially discussed, insight into the role titin plays in active tension development, such as length-dependent activation and contraction from longer muscle lengths.
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Affiliation(s)
- Wolfgang A Linke
- Institute of Physiology II, University of Münster, Germany; Clinic for Cardiology and Pneumology, University Medical Center Göttingen, Germany; German Centre for Cardiovascular Research, Berlin, Germany.
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9
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Titin activates myosin filaments in skeletal muscle by switching from an extensible spring to a mechanical rectifier. Proc Natl Acad Sci U S A 2023; 120:e2219346120. [PMID: 36812205 PMCID: PMC9992839 DOI: 10.1073/pnas.2219346120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023] Open
Abstract
Titin is a molecular spring in parallel with myosin motors in each muscle half-sarcomere, responsible for passive force development at sarcomere length (SL) above the physiological range (>2.7 μm). The role of titin at physiological SL is unclear and is investigated here in single intact muscle cells of the frog (Rana esculenta), by combining half-sarcomere mechanics and synchrotron X-ray diffraction in the presence of 20 μM para-nitro-blebbistatin, which abolishes the activity of myosin motors and maintains them in the resting state even during activation of the cell by electrical stimulation. We show that, during cell activation at physiological SL, titin in the I-band switches from an SL-dependent extensible spring (OFF-state) to an SL-independent rectifier (ON-state) that allows free shortening while resisting stretch with an effective stiffness of ~3 pN nm-1 per half-thick filament. In this way, I-band titin efficiently transmits any load increase to the myosin filament in the A-band. Small-angle X-ray diffraction signals reveal that, with I-band titin ON, the periodic interactions of A-band titin with myosin motors alter their resting disposition in a load-dependent manner, biasing the azimuthal orientation of the motors toward actin. This work sets the stage for future investigations on scaffold and mechanosensing-based signaling functions of titin in health and disease.
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10
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Bagley JR, Denes LT, McCarthy JJ, Wang ET, Murach KA. The myonuclear domain in adult skeletal muscle fibres: past, present and future. J Physiol 2023; 601:723-741. [PMID: 36629254 PMCID: PMC9931674 DOI: 10.1113/jp283658] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 01/06/2023] [Indexed: 01/12/2023] Open
Abstract
Most cells in the body are mononuclear whereas skeletal muscle fibres are uniquely multinuclear. The nuclei of muscle fibres (myonuclei) are usually situated peripherally which complicates the equitable distribution of gene products. Myonuclear abundance can also change under conditions such as hypertrophy and atrophy. Specialised zones in muscle fibres have different functions and thus distinct synthetic demands from myonuclei. The complex structure and regulatory requirements of multinuclear muscle cells understandably led to the hypothesis that myonuclei govern defined 'domains' to maintain homeostasis and facilitate adaptation. The purpose of this review is to provide historical context for the myonuclear domain and evaluate its veracity with respect to mRNA and protein distribution resulting from myonuclear transcription. We synthesise insights from past and current in vitro and in vivo genetically modified models for studying the myonuclear domain under dynamic conditions. We also cover the most contemporary knowledge on mRNA and protein transport in muscle cells. Insights from emerging technologies such as single myonuclear RNA-sequencing further inform our discussion of the myonuclear domain. We broadly conclude: (1) the myonuclear domain can be flexible during muscle fibre growth and atrophy, (2) the mechanisms and role of myonuclear loss and motility deserve further consideration, (3) mRNA in muscle is actively transported via microtubules and locally restricted, but proteins may travel far from a myonucleus of origin and (4) myonuclear transcriptional specialisation extends beyond the classic neuromuscular and myotendinous populations. A deeper understanding of the myonuclear domain in muscle may promote effective therapies for ageing and disease.
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Affiliation(s)
- James R. Bagley
- Muscle Physiology Laboratory, Department of Kinesiology, San Francisco State University, San Francisco, California
| | | | - John J. McCarthy
- The Center for Muscle Biology, University of Kentucky, Lexington, Kentucky
- Department of Physiology, College of Medicine, University of Kentucky
| | - Eric T. Wang
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics, University of Florida, Gainesville, Florida
- Myology Institute, University of Florida
- Genetics Institute, University of Florida
| | - Kevin A. Murach
- Exercise Science Research Center, Department of Health, Human Performance, and Recreation, University of Arkansas, Fayetteville, Arkansas
- Cell and Molecular Biology Graduate Program, University of Arkansas
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11
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Rbm20 ΔRRM Mice, Expressing a Titin Isoform with Lower Stiffness, Are Protected from Mechanical Ventilation-Induced Diaphragm Weakness. Int J Mol Sci 2022; 23:ijms232415689. [PMID: 36555335 PMCID: PMC9779751 DOI: 10.3390/ijms232415689] [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: 11/10/2022] [Revised: 12/06/2022] [Accepted: 12/08/2022] [Indexed: 12/14/2022] Open
Abstract
Diaphragm weakness frequently develops in mechanically ventilated critically ill patients and is associated with increased morbidity, including ventilator weaning failure, mortality, and health care costs. The mechanisms underlying diaphragm weakness are incompletely understood but may include the elastic properties of titin, a giant protein whose layout in the muscle's sarcomeres makes it an ideal candidate to sense ventilation-induced diaphragm unloading, resulting in downstream signaling through titin-binding proteins. In the current study, we investigated whether modulating titin stiffness affects the development of diaphragm weakness during mechanical ventilation. To this end, we ventilated genetically engineered mice with reduced titin stiffness (Rbm20ΔRRM), and robust (TtnΔIAjxn) or severely (TtnΔ112-158) increased titin stiffness for 8 h, and assessed diaphragm contractility and protein expression of titin-binding proteins. Mechanical ventilation reduced the maximum active tension of the diaphragm in WT, TtnΔIAjxn and TtnΔ112-158 mice. However, in Rbm20ΔRRM mice maximum active tension was preserved after ventilation. Analyses of titin binding proteins suggest that muscle ankyrin repeat proteins (MARPs) 1 and 2 may play a role in the adaptation of the diaphragm to mechanical ventilation, and the preservation of diaphragm contractility in Rbm20ΔRRM mice. Thus, Rbm20ΔRRM mice, expressing titin isoforms with lower stiffness, are protected from mechanical ventilation-induced diaphragm weakness, suggesting that titin elasticity may modulate the diaphragm's response to unloading during mechanical ventilation.
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Murach KA, Liu Z, Jude B, Figueiredo VC, Wen Y, Khadgi S, Lim S, Morena da Silva F, Greene NP, Lanner JT, McCarthy JJ, Vechetti IJ, von Walden F. Multi-transcriptome analysis following an acute skeletal muscle growth stimulus yields tools for discerning global and MYC regulatory networks. J Biol Chem 2022; 298:102515. [PMID: 36150502 PMCID: PMC9583450 DOI: 10.1016/j.jbc.2022.102515] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 09/15/2022] [Accepted: 09/17/2022] [Indexed: 02/01/2023] Open
Abstract
Myc is a powerful transcription factor implicated in epigenetic reprogramming, cellular plasticity, and rapid growth as well as tumorigenesis. Cancer in skeletal muscle is extremely rare despite marked and sustained Myc induction during loading-induced hypertrophy. Here, we investigated global, actively transcribed, stable, and myonucleus-specific transcriptomes following an acute hypertrophic stimulus in mouse plantaris. With these datasets, we define global and Myc-specific dynamics at the onset of mechanical overload-induced muscle fiber growth. Data collation across analyses reveals an under-appreciated role for the muscle fiber in extracellular matrix remodeling during adaptation, along with the contribution of mRNA stability to epigenetic-related transcript levels in muscle. We also identify Runx1 and Ankrd1 (Marp1) as abundant myonucleus-enriched loading-induced genes. We observed that a strong induction of cell cycle regulators including Myc occurs with mechanical overload in myonuclei. Additionally, in vivo Myc-controlled gene expression in the plantaris was defined using a genetic muscle fiber-specific doxycycline-inducible Myc-overexpression model. We determined Myc is implicated in numerous aspects of gene expression during early-phase muscle fiber growth. Specifically, brief induction of Myc protein in muscle represses Reverbα, Reverbβ, and Myh2 while increasing Rpl3, recapitulating gene expression in myonuclei during acute overload. Experimental, comparative, and in silico analyses place Myc at the center of a stable and actively transcribed, loading-responsive, muscle fiber-localized regulatory hub. Collectively, our experiments are a roadmap for understanding global and Myc-mediated transcriptional networks that regulate rapid remodeling in postmitotic cells. We provide open webtools for exploring the five RNA-seq datasets as a resource to the field.
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Affiliation(s)
- Kevin A. Murach
- Department of Health, Human Performance, and Recreation, Exercise Science Research Center, University of Arkansas, Fayetteville, Arkansas, USA,Cell and Molecular Biology Graduate Program, University of Arkansas, Fayetteville, Arkansas, USA,For correspondence: Kevin A. Murach; Ivan J. Vechetti; Ferdinand von Walden
| | - Zhengye Liu
- Department of Physiology and Pharmacology, Karolinska Institute, Solna, Sweden
| | - Baptiste Jude
- Department of Physiology and Pharmacology, Karolinska Institute, Solna, Sweden,Department of Women’s and Children’s Health, Karolinska Institute, Solna, Sweden
| | - Vandre C. Figueiredo
- Center for Muscle Biology, University of Kentucky, Lexington, Kentucky, USA,Department of Physiology, University of Kentucky, Lexington, Kentucky, USA
| | - Yuan Wen
- Center for Muscle Biology, University of Kentucky, Lexington, Kentucky, USA,Department of Physical Therapy, University of Kentucky, Lexington, Kentucky, USA
| | - Sabin Khadgi
- Department of Health, Human Performance, and Recreation, Exercise Science Research Center, University of Arkansas, Fayetteville, Arkansas, USA
| | - Seongkyun Lim
- Department of Health, Human Performance, and Recreation, Exercise Science Research Center, University of Arkansas, Fayetteville, Arkansas, USA,Cachexia Research Laboratory, University of Arkansas, Fayetteville, Arkansas, USA
| | - Francielly Morena da Silva
- Department of Health, Human Performance, and Recreation, Exercise Science Research Center, University of Arkansas, Fayetteville, Arkansas, USA,Cachexia Research Laboratory, University of Arkansas, Fayetteville, Arkansas, USA
| | - Nicholas P. Greene
- Department of Health, Human Performance, and Recreation, Exercise Science Research Center, University of Arkansas, Fayetteville, Arkansas, USA,Cell and Molecular Biology Graduate Program, University of Arkansas, Fayetteville, Arkansas, USA,Cachexia Research Laboratory, University of Arkansas, Fayetteville, Arkansas, USA
| | - Johanna T. Lanner
- Department of Physiology and Pharmacology, Karolinska Institute, Solna, Sweden
| | - John J. McCarthy
- Center for Muscle Biology, University of Kentucky, Lexington, Kentucky, USA,Department of Physiology, University of Kentucky, Lexington, Kentucky, USA
| | - Ivan J. Vechetti
- Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Nebraska, USA,For correspondence: Kevin A. Murach; Ivan J. Vechetti; Ferdinand von Walden
| | - Ferdinand von Walden
- Department of Women’s and Children’s Health, Karolinska Institute, Solna, Sweden,For correspondence: Kevin A. Murach; Ivan J. Vechetti; Ferdinand von Walden
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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
- 1Institute of Genetic and Biomedical Research (IRGB), National Research Council (CNR), Milan Unit, Milan, Italy,2IRCCS Humanitas Research Hospital, Rozzano (Milan), Italy
| | - Julius Bogomolovas
- 3Division of Cardiovascular Medicine, Department of Medicine Cardiology, University of California, San Diego, La Jolla, California
| | - Ju Chen
- 3Division of Cardiovascular Medicine, Department of Medicine Cardiology, University of California, San Diego, La Jolla, California
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14
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van der Pijl RJ, Domenighetti AA, Sheikh F, Ehler E, Ottenheijm CAC, Lange S. The titin N2B and N2A regions: biomechanical and metabolic signaling hubs in cross-striated muscles. Biophys Rev 2021; 13:653-677. [PMID: 34745373 PMCID: PMC8553726 DOI: 10.1007/s12551-021-00836-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 08/23/2021] [Indexed: 02/07/2023] Open
Abstract
Muscle specific signaling has been shown to originate from myofilaments and their associated cellular structures, including the sarcomeres, costameres or the cardiac intercalated disc. Two signaling hubs that play important biomechanical roles for cardiac and/or skeletal muscle physiology are the N2B and N2A regions in the giant protein titin. Prominent proteins associated with these regions in titin are chaperones Hsp90 and αB-crystallin, members of the four-and-a-half LIM (FHL) and muscle ankyrin repeat protein (Ankrd) families, as well as thin filament-associated proteins, such as myopalladin. This review highlights biological roles and properties of the titin N2B and N2A regions in health and disease. Special emphasis is placed on functions of Ankrd and FHL proteins as mechanosensors that modulate muscle-specific signaling and muscle growth. This region of the sarcomere also emerged as a hotspot for the modulation of passive muscle mechanics through altered titin phosphorylation and splicing, as well as tethering mechanisms that link titin to the thin filament system.
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Affiliation(s)
| | - Andrea A. Domenighetti
- Shirley Ryan AbilityLab, Chicago, IL USA
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, IL USA
| | - Farah Sheikh
- Division of Cardiology, School of Medicine, UC San Diego, La Jolla, CA USA
| | - Elisabeth Ehler
- Randall Centre for Cell and Molecular Biophysics, School of Cardiovascular Medicine and Sciences, King’s College London, London, UK
| | - Coen A. C. Ottenheijm
- Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ USA
- Department of Physiology, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Stephan Lange
- Division of Cardiology, School of Medicine, UC San Diego, La Jolla, CA USA
- Department of Molecular and Clinical Medicine, University of Gothenburg, Gothenburg, Sweden
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15
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Abstract
The sarcomeric titin springs and accessory proteins modulate muscle force and mechanical signaling at the N2A signalosome.
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Affiliation(s)
- Anthony L Hessel
- Institute of Physiology II, University of Muenster, Muenster, Germany
| | - Wolfgang A Linke
- Institute of Physiology II, University of Muenster, Muenster, Germany
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16
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Adewale AO, Ahn YH. Titin N2A Domain and Its Interactions at the Sarcomere. Int J Mol Sci 2021; 22:ijms22147563. [PMID: 34299183 PMCID: PMC8305307 DOI: 10.3390/ijms22147563] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 07/09/2021] [Accepted: 07/12/2021] [Indexed: 12/16/2022] Open
Abstract
Titin is a giant protein in the sarcomere that plays an essential role in muscle contraction with actin and myosin filaments. However, its utility goes beyond mechanical functions, extending to versatile and complex roles in sarcomere organization and maintenance, passive force, mechanosensing, and signaling. Titin’s multiple functions are in part attributed to its large size and modular structures that interact with a myriad of protein partners. Among titin’s domains, the N2A element is one of titin’s unique segments that contributes to titin’s functions in compliance, contraction, structural stability, and signaling via protein–protein interactions with actin filament, chaperones, stress-sensing proteins, and proteases. Considering the significance of N2A, this review highlights structural conformations of N2A, its predisposition for protein–protein interactions, and its multiple interacting protein partners that allow the modulation of titin’s biological effects. Lastly, the nature of N2A for interactions with chaperones and proteases is included, presenting it as an important node that impacts titin’s structural and functional integrity.
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Affiliation(s)
- Robbert J van der Pijl
- Department of Physiology, Amsterdam University Medical Centers, Amsterdam, Netherlands.,Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
| | - Coen A C Ottenheijm
- Department of Physiology, Amsterdam University Medical Centers, Amsterdam, Netherlands.,Department of Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
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Cremo C, Moss RL, Granzier H. Further progress in understanding of myofibrillar function in health and disease. J Gen Physiol 2021; 153:212438. [PMID: 34170286 PMCID: PMC8238634 DOI: 10.1085/jgp.202112972] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Affiliation(s)
- Christine Cremo
- Department of Pharmacology, School of Medicine, University of Nevada, Reno, Reno, NV
| | - Richard L Moss
- Cardiovascular Research Center, Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin, Madison, WI
| | - Henk Granzier
- Cellular and Molecular Medicine, University of Arizona, Tucson, AZ
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