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O’Neill A, Martinez AL, Mueller AL, Huang W, Accorsi A, Kane MA, Eyerman D, Bloch RJ. Optimization of Xenografting Methods for Generating Human Skeletal Muscle in Mice. Cell Transplant 2024; 33:9636897241242624. [PMID: 38600801 PMCID: PMC11010746 DOI: 10.1177/09636897241242624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 03/08/2024] [Accepted: 03/12/2024] [Indexed: 04/12/2024] Open
Abstract
Xenografts of human skeletal muscle generated in mice can be used to study muscle pathology and to test drugs designed to treat myopathies and muscular dystrophies for their efficacy and specificity in human tissue. We previously developed methods to generate mature human skeletal muscles in immunocompromised mice starting with human myogenic precursor cells (hMPCs) from healthy individuals and individuals with facioscapulohumeral muscular dystrophy (FSHD). Here, we examine a series of alternative treatments at each stage in order to optimize engraftment. We show that (i) X-irradiation at 25Gy is optimal in preventing regeneration of murine muscle while supporting robust engraftment and the formation of human fibers without significant murine contamination; (ii) hMPC lines differ in their capacity to engraft; (iii) some hMPC lines yield grafts that respond better to intermittent neuromuscular electrical stimulation (iNMES) than others; (iv) some lines engraft better in male than in female mice; (v) coinjection of hMPCs with laminin, gelatin, Matrigel, or Growdex does not improve engraftment; (vi) BaCl2 is an acceptable replacement for cardiotoxin, but other snake venom preparations and toxins, including the major component of cardiotoxin, cytotoxin 5, are not; and (vii) generating grafts in both hindlimbs followed by iNMES of each limb yields more robust grafts than housing mice in cages with running wheels. Our results suggest that replacing cardiotoxin with BaCl2 and engrafting both tibialis anterior muscles generates robust grafts of adult human muscle tissue in mice.
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Affiliation(s)
- Andrea O’Neill
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Anna Llach Martinez
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Amber L. Mueller
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
- Cell Metabolism, Cambridge, MA, USA
| | - Weiliang Huang
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD, USA
| | - Anthony Accorsi
- Fulcrum Therapeutics, Cambridge, MA, USA
- Blackbird Laboratories, Baltimore, MD, USA
| | - Maureen A. Kane
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD, USA
| | - David Eyerman
- Fulcrum Therapeutics, Cambridge, MA, USA
- Apellis Pharmaceuticals, Waltham, MA, USA
| | - Robert J. Bloch
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
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Lukyanenko VI, Muriel JM, Bloch RJ. Elevated Ca 2+ at the triad junction underlies dysregulation of Ca 2+ signaling in dysferlinopathy. Biophys J 2023; 122:34a. [PMID: 36783771 DOI: 10.1016/j.bpj.2022.11.403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Affiliation(s)
- Valeriy I Lukyanenko
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Joaquin M Muriel
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Robert J Bloch
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
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3
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Lukyanenko V, Muriel J, Garman D, Breydo L, Bloch RJ. Elevated Ca2+ at the triad junction underlies dysregulation of Ca2+ signaling in dysferlin-null skeletal muscle. Front Physiol 2022; 13:1032447. [PMID: 36406982 PMCID: PMC9669649 DOI: 10.3389/fphys.2022.1032447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 10/14/2022] [Indexed: 11/05/2022] Open
Abstract
Dysferlin-null A/J myofibers generate abnormal Ca2+ transients that are slightly reduced in amplitude compared to controls. These are further reduced in amplitude by hypoosmotic shock and often appear as Ca2+ waves (Lukyanenko et al., J. Physiol., 2017). Ca2+ waves are typically associated with Ca2+-induced Ca2+ release, or CICR, which can be myopathic. We tested the ability of a permeable Ca2+ chelator, BAPTA-AM, to inhibit CICR in injured dysferlin-null fibers and found that 10–50 nM BAPTA-AM suppressed all Ca2+ waves. The same concentrations of BAPTA-AM increased the amplitude of the Ca2+ transient in A/J fibers to wild type levels and protected transients against the loss of amplitude after hypoosmotic shock, as also seen in wild type fibers. Incubation with 10 nM BAPTA-AM led to intracellular BAPTA concentrations of ∼60 nM, as estimated with its fluorescent analog, Fluo-4AM. This should be sufficient to restore intracellular Ca2+ to levels seen in wild type muscle. Fluo-4AM was ∼10-fold less effective than BAPTA-AM, however, consistent with its lower affinity for Ca2+. EGTA, which has an affinity for Ca2+ similar to BAPTA, but with much slower kinetics of binding, was even less potent when introduced as the -AM derivative. By contrast, a dysferlin variant with GCaMP6fu in place of its C2A domain accumulated at triad junctions, like wild type dysferlin, and suppressed all abnormal Ca2+ signaling. GCaMP6fu introduced as a Venus chimera did not accumulate at junctions and failed to suppress abnormal Ca2+ signaling. Our results suggest that leak of Ca2+ into the triad junctional cleft underlies dysregulation of Ca2+ signaling in dysferlin-null myofibers, and that dysferlin’s C2A domain suppresses abnormal Ca2+ signaling and protects muscle against injury by binding Ca2+ in the cleft.
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Affiliation(s)
- Valeriy Lukyanenko
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Joaquin Muriel
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Daniel Garman
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, United States
- Program in Biochemistry and Molecular Biology, University of Maryland, Baltimore, MD, United States
| | - Leonid Breydo
- Formulation Development, Regeneron Pharmaceuticals, Tarrytown, NY, United States
| | - Robert J. Bloch
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, United States
- *Correspondence: Robert J. Bloch,
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Muriel J, Lukyanenko V, Kwiatkowski T, Bhattacharya S, Garman D, Weisleder N, Bloch RJ. The C2 domains of dysferlin: Roles in membrane localization, Ca
2+
signaling and sarcolemmal repair. J Physiol 2022; 600:1953-1968. [PMID: 35156706 PMCID: PMC9285653 DOI: 10.1113/jp282648] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 02/03/2022] [Indexed: 11/08/2022] Open
Abstract
Dysferlin is an integral membrane protein of the transverse tubules of skeletal muscle that is mutated or absent in limb girdle muscular dystrophy 2B and Miyoshi myopathy. Here we examine the role of dysferlin's seven C2 domains, C2A through C2G, in membrane repair and Ca2+ release, as well as in targeting dysferlin to the transverse tubules of skeletal muscle. We report that deletion of either domain C2A or C2B inhibits membrane repair completely, whereas deletion of C2C, C2D, C2E, C2F or C2G causes partial loss of membrane repair that is exacerbated in the absence of extracellular Ca2+ . Deletion of C2C, C2D, C2E, C2F or C2G also causes significant changes in Ca2+ release, measured as the amplitude of the Ca2+ transient before or after hypo-osmotic shock and the appearance of Ca2+ waves. Most deletants accumulate in endoplasmic reticulum. Only the C2A domain can be deleted without affecting dysferlin trafficking to transverse tubules, but Dysf-ΔC2A fails to support normal Ca2+ signalling after hypo-osmotic shock. Our data suggest that (i) every C2 domain contributes to repair; (ii) all C2 domains except C2B regulate Ca2+ signalling; (iii) transverse tubule localization is insufficient for normal Ca2+ signalling; and (iv) Ca2+ dependence of repair is mediated by C2C through C2G. Thus, dysferlin's C2 domains have distinct functions in Ca2+ signalling and sarcolemmal membrane repair and may play distinct roles in skeletal muscle. KEY POINTS: Dysferlin, a transmembrane protein containing seven C2 domains, C2A through C2G, concentrates in transverse tubules of skeletal muscle, where it stabilizes voltage-induced Ca2+ transients and participates in sarcolemmal membrane repair. Each of dysferlin's C2 domains except C2B regulate Ca2+ signalling. Localization of dysferlin variants to the transverse tubules is not sufficient to support normal Ca2+ signalling or membrane repair. Each of dysferlin's C2 domains contributes to sarcolemmal membrane repair. The Ca2+ dependence of membrane repair is mediated by C2C through C2G. Dysferlin's C2 domains therefore have distinct functions in Ca2+ signalling and sarcolemmal membrane repair.
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Affiliation(s)
- Joaquin Muriel
- Department of Physiology University of Maryland School of Medicine Baltimore MD 21208
| | - Valeriy Lukyanenko
- Department of Physiology University of Maryland School of Medicine Baltimore MD 21208
| | - Tom Kwiatkowski
- Department of Physiology The Ohio State College of Medicine Columbus OH 43210
| | - Sayak Bhattacharya
- Department of Physiology The Ohio State College of Medicine Columbus OH 43210
| | - Daniel Garman
- Department of Physiology University of Maryland School of Medicine Baltimore MD 21208
| | - Noah Weisleder
- Department of Physiology The Ohio State College of Medicine Columbus OH 43210
| | - Robert J. Bloch
- Department of Physiology University of Maryland School of Medicine Baltimore MD 21208
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5
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Lukyanenko VI, Muriel J, Bloch RJ. Specific effects of individual C2 domains on recovery of voltage-induced SR calcium release after osmotic shock in muscle fibers from dysferlin-null mice. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.2258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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6
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Garcia-Pelagio KP, Bloch RJ. Biomechanical Properties of the Sarcolemma and Costameres of Skeletal Muscle Lacking Desmin. Front Physiol 2021; 12:706806. [PMID: 34489727 PMCID: PMC8416993 DOI: 10.3389/fphys.2021.706806] [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: 05/08/2021] [Accepted: 07/13/2021] [Indexed: 01/23/2023] Open
Abstract
Intermediate filaments (IFs), composed primarily by desmin and keratins, link the myofibrils to each other, to intracellular organelles, and to the sarcolemma. There they may play an important role in transfer of contractile force from the Z-disks and M-lines of neighboring myofibrils to costameres at the membrane, across the membrane to the extracellular matrix, and ultimately to the tendon (“lateral force transmission”). We measured the elasticity of the sarcolemma and the connections it makes at costameres with the underlying contractile apparatus of individual fast twitch muscle fibers of desmin-null mice. By positioning a suction pipet to the surface of the sarcolemma and applying increasing pressure, we determined the pressure at which the sarcolemma separated from nearby sarcomeres, Pseparation, and the pressure at which the isolated sarcolemma burst, Pbursting. We also examined the time required for the intact sarcolemma-costamere-sarcomere complex to reach equilibrium at lower pressures. All measurements showed the desmin-null fibers to have slower equilibrium times and lower Pseparation and Pbursting than controls, suggesting that the sarcolemma and its costameric links to nearby contractile structures were weaker in the absence of desmin. Comparisons to earlier values determined for muscles lacking dystrophin or synemin suggest that the desmin-null phenotype is more stable than the former and less stable than the latter. Our results are consistent with the moderate myopathy seen in desmin-null muscles and support the idea that desmin contributes significantly to sarcolemmal stability and lateral force transmission.
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Affiliation(s)
- Karla P Garcia-Pelagio
- Departamento de Fisica, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Robert J Bloch
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, United States
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7
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Zhang H, Bryson VG, Wang C, Li T, Kerr JP, Wilson R, Muoio DM, Bloch RJ, Ward C, Rosenberg PB. Desmin interacts with STIM1 and coordinates Ca2+ signaling in skeletal muscle. JCI Insight 2021; 6:143472. [PMID: 34494555 PMCID: PMC8492340 DOI: 10.1172/jci.insight.143472] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 07/28/2021] [Indexed: 12/30/2022] Open
Abstract
Stromal interaction molecule 1 (STIM1), the sarcoplasmic reticulum (SR) transmembrane protein, activates store-operated Ca2+ entry (SOCE) in skeletal muscle and, thereby, coordinates Ca2+ homeostasis, Ca2+-dependent gene expression, and contractility. STIM1 occupies space in the junctional SR membrane of the triads and the longitudinal SR at the Z-line. How STIM1 is organized and is retained in these specific subdomains of the SR is unclear. Here, we identified desmin, the major type III intermediate filament protein in muscle, as a binding partner for STIM1 based on a yeast 2-hybrid screen. Validation of the desmin-STIM1 interaction by immunoprecipitation and immunolocalization confirmed that the CC1-SOAR domains of STIM1 interact with desmin to enhance STIM1 oligomerization yet limit SOCE. Based on our studies of desmin-KO mice, we developed a model wherein desmin connected STIM1 at the Z-line in order to regulate the efficiency of Ca2+ refilling of the SR. Taken together, these studies showed that desmin-STIM1 assembles a cytoskeletal-SR connection that is important for Ca2+ signaling in skeletal muscle.
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Affiliation(s)
- Hengtao Zhang
- Department of Medicine and
- Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, North Carolina, USA
| | - Victoria Graham Bryson
- Department of Medicine and
- Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, North Carolina, USA
| | - Chaojian Wang
- Department of Medicine and
- Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, North Carolina, USA
| | - TianYu Li
- Department of Medicine and
- Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, North Carolina, USA
| | - Jaclyn P. Kerr
- Department of Physiology and
- Department of Orthopedic Surgery, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Rebecca Wilson
- Department of Medicine and
- Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, North Carolina, USA
| | - Deborah M. Muoio
- Department of Medicine and
- Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, North Carolina, USA
| | - Robert J. Bloch
- Department of Physiology and
- Department of Orthopedic Surgery, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Christopher Ward
- Department of Physiology and
- Department of Orthopedic Surgery, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Paul B. Rosenberg
- Department of Medicine and
- Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, North Carolina, USA
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8
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Abstract
µ-Crystallin is a NADPH-regulated thyroid hormone binding protein encoded by the CRYM gene in humans. It is primarily expressed in the brain, muscle, prostate, and kidney, where it binds thyroid hormones, which regulate metabolism and thermogenesis. It also acts as a ketimine reductase in the lysine degradation pathway when it is not bound to thyroid hormone. Mutations in CRYM can result in non-syndromic deafness, while its aberrant expression, predominantly in the brain but also in other tissues, has been associated with psychiatric, neuromuscular, and inflammatory diseases. CRYM expression is highly variable in human skeletal muscle, with 15% of individuals expressing ≥13 fold more CRYM mRNA than the median level. Ablation of the Crym gene in murine models results in the hypertrophy of fast twitch muscle fibers and an increase in fat mass of mice fed a high fat diet. Overexpression of Crym in mice causes a shift in energy utilization away from glycolysis towards an increase in the catabolism of fat via β-oxidation, with commensurate changes of metabolically involved transcripts and proteins. The history, attributes, functions, and diseases associated with CRYM, an important modulator of metabolism, are reviewed.
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Affiliation(s)
- Christian J Kinney
- Department of Physiology School of Medicine, University of Maryland, Baltimore, Baltimore, MD 21201
| | - Robert J Bloch
- Department of Physiology School of Medicine, University of Maryland, Baltimore, Baltimore, MD 21201
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Kinney CJ, O'Neill A, Noland K, Huang W, Muriel J, Lukyanenko V, Kane MA, Ward CW, Collier AF, Roche JA, McLenithan JC, Reed PW, Bloch RJ. μ-Crystallin in Mouse Skeletal Muscle Promotes a Shift from Glycolytic toward Oxidative Metabolism. Curr Res Physiol 2021; 4:47-59. [PMID: 34746826 PMCID: PMC8562245 DOI: 10.1016/j.crphys.2021.02.003] [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] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 01/31/2021] [Accepted: 02/04/2021] [Indexed: 01/24/2023] Open
Abstract
μ-Crystallin, encoded by the CRYM gene, binds the thyroid hormones, T3 and T4. Because T3 and T4 are potent regulators of metabolism and gene expression, and CRYM levels in human skeletal muscle can vary widely, we investigated the effects of overexpression of Crym. We generated transgenic mice, Crym tg, that expressed Crym protein specifically in skeletal muscle at levels 2.6-147.5 fold higher than in controls. Muscular functions, Ca2+ transients, contractile force, fatigue, running on treadmills or wheels, were not significantly altered, although T3 levels in tibialis anterior (TA) muscle were elevated ~190-fold and serum T4 was decreased 1.2-fold. Serum T3 and thyroid stimulating hormone (TSH) levels were unaffected. Crym transgenic mice studied in metabolic chambers showed a significant decrease in the respiratory exchange ratio (RER) corresponding to a 13.7% increase in fat utilization as an energy source compared to controls. Female but not male Crym tg mice gained weight more rapidly than controls when fed high fat or high simple carbohydrate diets. Although labeling for myosin heavy chains showed no fiber type differences in TA or soleus muscles, application of machine learning algorithms revealed small but significant morphological differences between Crym tg and control soleus fibers. RNA-seq and gene ontology enrichment analysis showed a significant shift towards genes associated with slower muscle function and its metabolic correlate, β-oxidation. Protein expression showed a similar shift, though with little overlap. Our study shows that μ-crystallin plays an important role in determining substrate utilization in mammalian muscle and that high levels of μ-crystallin are associated with a shift toward greater fat metabolism.
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Affiliation(s)
- Christian J. Kinney
- Department of Physiology School of Medicine, University of Maryland Baltimore, Baltimore, MD, 21201, USA
| | - Andrea O'Neill
- Department of Physiology School of Medicine, University of Maryland Baltimore, Baltimore, MD, 21201, USA
| | - Kaila Noland
- Department of Physiology School of Medicine, University of Maryland Baltimore, Baltimore, MD, 21201, USA
| | - Weiliang Huang
- Department of Pharmaceutical Sciences School of Pharmacy, University of Maryland Baltimore, Baltimore, MD, 21201, USA
| | - Joaquin Muriel
- Department of Physiology School of Medicine, University of Maryland Baltimore, Baltimore, MD, 21201, USA
| | - Valeriy Lukyanenko
- Department of Physiology School of Medicine, University of Maryland Baltimore, Baltimore, MD, 21201, USA
| | - Maureen A. Kane
- Department of Pharmaceutical Sciences School of Pharmacy, University of Maryland Baltimore, Baltimore, MD, 21201, USA
| | - Christopher W. Ward
- Department of Orthopedics School of Medicine, University of Maryland Baltimore, Baltimore, MD, 21201, USA
| | - Alyssa F. Collier
- Department of Physiology School of Medicine, University of Maryland Baltimore, Baltimore, MD, 21201, USA
| | - Joseph A. Roche
- Department of Physiology School of Medicine, University of Maryland Baltimore, Baltimore, MD, 21201, USA
| | - John C. McLenithan
- Department of Medicine School of Medicine, University of Maryland Baltimore, Baltimore, MD, 21201, USA
| | - Patrick W. Reed
- Department of Physiology School of Medicine, University of Maryland Baltimore, Baltimore, MD, 21201, USA
| | - Robert J. Bloch
- Department of Physiology School of Medicine, University of Maryland Baltimore, Baltimore, MD, 21201, USA
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10
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Lukyanenko VI, Muriel JM, Bloch RJ. Effects of Point Mutations of Dysferlin on Ca2+ Signaling in Murine Skeletal Myofibers. Biophys J 2021. [DOI: 10.1016/j.bpj.2020.11.1568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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11
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Kyba M, Bloch RJ, Dumonceaux J, Harper SQ, van der Maarel SM, Sverdrup FM, Wagner KR, van Engelen B, Chen YW. Meeting report: the 2020 FSHD International Research Congress. Skelet Muscle 2020; 10:36. [PMID: 33292505 PMCID: PMC7721607 DOI: 10.1186/s13395-020-00253-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 11/16/2020] [Indexed: 11/16/2022] Open
Affiliation(s)
- Michael Kyba
- Department of Pediatrics, University of Minnesota, Minneapolis, MN, 55104, USA
| | - Robert J Bloch
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Julie Dumonceaux
- NIHR Biomedical Research Centre, University College London, Great Ormond Street Institute of Child Health and Great Ormond Street Hospital NHS Trust, London, WC1N 1EH, UK
| | - Scott Q Harper
- Department of Pediatrics, The Ohio State University, Columbus, OH, 43205, USA.,Center for Gene Therapy, The Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH, 43205, USA
| | | | - Francis M Sverdrup
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University, Saint Louis, MO, 63104, USA
| | - Kathryn R Wagner
- Center for Genetic Muscle Disorders, Kennedy Krieger Institute, Baltimore, MD, 21205, USA.,Departments of Neurology and Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD, 21205, USA
| | - Baziel van Engelen
- Department of Neurology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Yi-Wen Chen
- Department of Genomics and Precision Medicine, The George Washington University, Washington, DC, 20052, USA. .,Center for Genetic Medicine Research, Children's National Research Institute, Washington, DC, 20010, USA.
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12
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Lukyanenko VI, Muriel JM, Bloch RJ. Effect of Bapta and Dysferlin's C2A Domain on Recovery of Ca2D Transients After Osmotic Shock in Dysferlin-Null Myofibers. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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13
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Muriel JM, O'Neill A, Kerr JP, Kleinhans-Welte E, Lovering RM, Bloch RJ. Keratin 18 is an integral part of the intermediate filament network in murine skeletal muscle. Am J Physiol Cell Physiol 2019; 318:C215-C224. [PMID: 31721615 DOI: 10.1152/ajpcell.00279.2019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [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: 01/26/2023]
Abstract
Intermediate filaments (IFs) contribute to force transmission, cellular integrity, and signaling in skeletal muscle. We previously identified keratin 19 (Krt19) as a muscle IF protein. We now report the presence of a second type I muscle keratin, Krt18. Krt18 mRNA levels are about half those for Krt19 and only 1:1,000th those for desmin; the protein was nevertheless detectable in immunoblots. Muscle function, measured by maximal isometric force in vivo, was moderately compromised in Krt18-knockout (Krt18-KO) or dominant-negative mutant mice (Krt18 DN), but structure was unaltered. Exogenous Krt18, introduced by electroporation, was localized in a reticulum around the contractile apparatus in wild-type muscle and to a lesser extent in muscle lacking Krt19 or desmin or both proteins. Exogenous Krt19, which was either reticular or aggregated in controls, became reticular more frequently in Krt19-null than in Krt18-null, desmin-null, or double-null muscles. Desmin was assembled into the reticulum normally in all genotypes. Notably, all three IF proteins appeared in overlapping reticular structures. We assessed the effect of Krt18 on susceptibility to injury in vivo by electroporating siRNA into tibialis anterior (TA) muscles of control and Krt19-KO mice and testing 2 wk later. Results showed a 33% strength deficit (reduction in maximal torque after injury) compared with siRNA-treated controls. Conversely, electroporation of siRNA to Krt19 into Krt18-null TA yielded a strength deficit of 18% after injury compared with controls. Our results suggest that Krt18 plays a complementary role to Krt19 in skeletal muscle in both assembling keratin-based filaments and transducing contractile force.
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Affiliation(s)
- Joaquin M Muriel
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Andrea O'Neill
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Jaclyn P Kerr
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Emily Kleinhans-Welte
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Richard M Lovering
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, Maryland
| | - Robert J Bloch
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
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14
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Abstract
Xenografts of skeletal muscle are used to study muscle repair and regeneration, mechanisms of muscular dystrophies, and potential cell therapies for musculoskeletal disorders. Typically, xenografting involves using an immunodeficient host that is pre-injured to create a niche for human cell engraftment. Cell type and method of delivery to muscle depend on the specific application, but can include myoblasts, satellite cells, induced pluripotent stem cells, mesangioblasts, immortalized muscle precursor cells, and other multipotent cell lines delivered locally or systemically. Some studies follow cell engraftment with interventions to enhance cell proliferation, migration, and differentiation into mature muscle fibers. Recently, several advances in xenografting human-derived muscle cells have been applied to study and treat Duchenne muscular dystrophy and Facioscapulohumeral muscular dystrophy. Here, we review the vast array of techniques available to aid researchers in designing future experiments aimed at creating robust muscle xenografts in rodent hosts.
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Affiliation(s)
- Amber L Mueller
- Department of Physiology, University of Maryland School of Medicine, 655 W. Baltimore St., Baltimore, MD, 21201, USA
| | - Robert J Bloch
- Department of Physiology, University of Maryland School of Medicine, 655 W. Baltimore St., Baltimore, MD, 21201, USA.
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15
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Mueller AL, O'Neill A, Jones TI, Llach A, Rojas LA, Sakellariou P, Stadler G, Wright WE, Eyerman D, Jones PL, Bloch RJ. Muscle xenografts reproduce key molecular features of facioscapulohumeral muscular dystrophy. Exp Neurol 2019; 320:113011. [PMID: 31306642 DOI: 10.1016/j.expneurol.2019.113011] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 06/17/2019] [Accepted: 07/09/2019] [Indexed: 12/07/2022]
Abstract
Aberrant expression of DUX4, a gene unique to humans and primates, causes Facioscapulohumeral Muscular Dystrophy-1 (FSHD), yet the pathogenic mechanism is unknown. As transgenic overexpression models have largely failed to replicate the genetic changes seen in FSHD, many studies of endogenously expressed DUX4 have been limited to patient biopsies and myogenic cell cultures, which never fully differentiate into mature muscle fibers. We have developed a method to xenograft immortalized human muscle precursor cells from patients with FSHD and first-degree relative controls into the tibialis anterior muscle compartment of immunodeficient mice, generating human muscle xenografts. We report that FSHD cells mature into organized and innervated human muscle fibers with minimal contamination of murine myonuclei. They also reconstitute the satellite cell niche within the xenografts. FSHD xenografts express DUX4 and DUX4 downstream targets, retain the 4q35 epigenetic signature of their original donors, and express a novel protein biomarker of FSHD, SLC34A2. Ours is the first scalable, mature in vivo human model of FSHD. It should be useful for studies of the pathogenic mechanism of the disease as well as for testing therapeutic strategies targeting DUX4 expression.
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Affiliation(s)
- Amber L Mueller
- Department of Physiology, University of Maryland, Baltimore, 655 W, Baltimore St., Baltimore, MD 21201, United States of America
| | - Andrea O'Neill
- Department of Physiology, University of Maryland, Baltimore, 655 W, Baltimore St., Baltimore, MD 21201, United States of America
| | - Takako I Jones
- Department of Pharmacology, University of Nevada, Reno School of Medicine, 1664 North Virginia Street, Reno, NV 89557, United States of America
| | - Anna Llach
- Department of Physiology, University of Maryland, Baltimore, 655 W, Baltimore St., Baltimore, MD 21201, United States of America
| | - Luis Alejandro Rojas
- Fulcrum Therapeutics, 26 Landsdowne St., Cambridge, MA 02139, United States of America
| | - Paraskevi Sakellariou
- Department of Physiology, University of Maryland, Baltimore, 655 W, Baltimore St., Baltimore, MD 21201, United States of America; FAME Laboratory Department of Exercise Science, University of Thessaly, Karies, Trikala 42100, Greece
| | - Guido Stadler
- Department of Cell Biology, UT Southwestern Medical Center Dallas, TX 75390, United States of America
| | - Woodring E Wright
- Department of Cell Biology, UT Southwestern Medical Center Dallas, TX 75390, United States of America
| | - David Eyerman
- Fulcrum Therapeutics, 26 Landsdowne St., Cambridge, MA 02139, United States of America
| | - Peter L Jones
- Department of Pharmacology, University of Nevada, Reno School of Medicine, 1664 North Virginia Street, Reno, NV 89557, United States of America
| | - Robert J Bloch
- Department of Physiology, University of Maryland, Baltimore, 655 W, Baltimore St., Baltimore, MD 21201, United States of America.
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16
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Lukyanenko VI, Muriel J, Bloch RJ. Role of Dysferlin's C2A Domain in Voltage-Induced Calcium Release After Osmotic Shock in Murine Skeletal Myofibers. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.2814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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17
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Garman DD, Muriel JM, Bloch RJ. Dysferlin Mutants: Defects in Trafficking and Association with Proteins of the Transverse Tubule. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.2194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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18
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Labuza A, Desmond PF, Mancini AE, Muriel J, Rizzo MA, Bloch RJ. Small Ankyrin 1 Interacts with Phospholamban to Regulate Muscle SERCA1. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.2073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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19
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Lukyanenko V, Muriel J, Bloch RJ. Dysferlin C2A Domain Is Involved in Recovery of Voltage-Induced SR Calcium Release after Osmotic Shock in Murine Muscle Fibers. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.2593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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20
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García-Pelagio KP, Chen L, Joca HC, Ward C, Jonathan Lederer W, Bloch RJ. Absence of synemin in mice causes structural and functional abnormalities in heart. J Mol Cell Cardiol 2018; 114:354-363. [PMID: 29247678 PMCID: PMC5850968 DOI: 10.1016/j.yjmcc.2017.12.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2016] [Revised: 11/22/2017] [Accepted: 12/12/2017] [Indexed: 12/28/2022]
Abstract
Cardiomyopathies have been linked to changes in structural proteins, including intermediate filament (IF) proteins located in the cytoskeleton. IFs associate with the contractile machinery and costameres of striated muscle and with intercalated disks in the heart. Synemin is a large IF protein that mediates the association of desmin with Z-disks and stabilizes intercalated disks. It also acts as an A-kinase anchoring protein (AKAP). In murine skeletal muscle, the absence of synemin causes a mild myopathy. Here, we report that the genetic silencing of synemin in mice (synm -/-) causes left ventricular systolic dysfunction at 3months and 12-16months of age, and left ventricular hypertrophy and dilatation at 12-16months of age. Isolated cardiomyocytes showed alterations in calcium handling that indicate defects intrinsic to the heart. Although contractile and costameric proteins remained unchanged in the old synm -/- hearts, we identified alterations in several signaling proteins (PKA-RII, ERK and p70S6K) critical to cardiomyocyte function. Our data suggest that synemin plays an important regulatory role in the heart and that the consequences of its absence are profound.
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Affiliation(s)
- Karla P García-Pelagio
- Department of Physiology, School of Medicine, University of Maryland, 655 W. Baltimore St., Baltimore, MD 21201, USA; Department of Physics, School of Science, Universidad Nacional Autónoma de México, Av. Universidad 3000, Mexico City 04320, Mexico
| | - Ling Chen
- Department of Physiology, School of Medicine, University of Maryland, 655 W. Baltimore St., Baltimore, MD 21201, USA; Department of Medicine, School of Medicine, University of Maryland, 655 W. Baltimore St., Baltimore, MD 21201, USA
| | - Humberto C Joca
- BioMET, University of Maryland, 111 S Penn St, Baltimore, MD 21201, USA; Department of Biochemistry and Immunology, Institute of Biological Sciences, Universidade Federal de Minas Gerais, Av Prof. Alfredo Balena, 190, Belo Horizonte, MG 30130, Brazil
| | - Christopher Ward
- School of Nursing and Department of Orthopedics, School of Medicine, University of Maryland,100 Penn St, Baltimore, MD 21201, USA
| | - W Jonathan Lederer
- Department of Physiology, School of Medicine, University of Maryland, 655 W. Baltimore St., Baltimore, MD 21201, USA; BioMET, University of Maryland, 111 S Penn St, Baltimore, MD 21201, USA
| | - Robert J Bloch
- Department of Physiology, School of Medicine, University of Maryland, 655 W. Baltimore St., Baltimore, MD 21201, USA.
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21
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Collier AF, Gumerson J, Lehtimäki K, Puoliväli J, Jones JW, Kane MA, Manne S, O'Neill A, Windish HP, Ahtoniemi T, Williams BA, Albrecht DE, Bloch RJ. Effect of Ibuprofen on Skeletal Muscle of Dysferlin-Null Mice. J Pharmacol Exp Ther 2017; 364:409-419. [PMID: 29284661 DOI: 10.1124/jpet.117.244244] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 12/21/2017] [Indexed: 12/19/2022] Open
Abstract
Ibuprofen, a nonsteroidal anti-inflammatory drug, and nitric oxide (NO) donors have been reported to reduce the severity of muscular dystrophies in mice associated with the absence of dystrophin or α-sarcoglycan, but their effects on mice that are dystrophic due to the absence of dysferlin have not been examined. We have tested ibuprofen, as well as isosorbide dinitrate (ISDN), a NO donor, to learn whether used alone or together they protect dysferlin-null muscle in A/J mice from large strain injury (LSI) induced by a series of high strain lengthening contractions. Mice were maintained on chow containing ibuprofen and ISDN for 4 weeks. They were then subjected to LSI and maintained on the drugs for 3 additional days. We measured loss of torque immediately following injury and at day 3 postinjury, fiber necrosis, and macrophage infiltration at day 3 postinjury, and serum levels of the drugs at the time of euthanasia. Loss of torque immediately after injury was not altered by the drugs. However, the torque on day 3 postinjury significantly decreased as a function of ibuprofen concentration in the serum (range, 0.67-8.2 µg/ml), independent of ISDN. The effects of ISDN on torque loss at day 3 postinjury were not significant. In long-term studies of dysferlinopathic BlAJ mice, lower doses of ibuprofen had no effects on muscle morphology, but reduced treadmill running by 40%. Our results indicate that ibuprofen can have deleterious effects on dysferlin-null muscle and suggest that its use at pharmacological doses should be avoided by individuals with dysferlinopathies.
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Affiliation(s)
- Alyssa F Collier
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland (A.F.C., J.G., S.M., A.O'N., R.J.B.); Charles River Laboratories, Kuopio, Finland (K.L., J.P., T.A.); Mass Spectrometry Center, Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland (M.A.K., J.W.J.); and Jain Foundation, Seattle, Washington (H.P.W., B.A.W., D.E.A.)
| | - Jessica Gumerson
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland (A.F.C., J.G., S.M., A.O'N., R.J.B.); Charles River Laboratories, Kuopio, Finland (K.L., J.P., T.A.); Mass Spectrometry Center, Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland (M.A.K., J.W.J.); and Jain Foundation, Seattle, Washington (H.P.W., B.A.W., D.E.A.)
| | - Kimmo Lehtimäki
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland (A.F.C., J.G., S.M., A.O'N., R.J.B.); Charles River Laboratories, Kuopio, Finland (K.L., J.P., T.A.); Mass Spectrometry Center, Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland (M.A.K., J.W.J.); and Jain Foundation, Seattle, Washington (H.P.W., B.A.W., D.E.A.)
| | - Jukka Puoliväli
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland (A.F.C., J.G., S.M., A.O'N., R.J.B.); Charles River Laboratories, Kuopio, Finland (K.L., J.P., T.A.); Mass Spectrometry Center, Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland (M.A.K., J.W.J.); and Jain Foundation, Seattle, Washington (H.P.W., B.A.W., D.E.A.)
| | - Jace W Jones
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland (A.F.C., J.G., S.M., A.O'N., R.J.B.); Charles River Laboratories, Kuopio, Finland (K.L., J.P., T.A.); Mass Spectrometry Center, Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland (M.A.K., J.W.J.); and Jain Foundation, Seattle, Washington (H.P.W., B.A.W., D.E.A.)
| | - Maureen A Kane
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland (A.F.C., J.G., S.M., A.O'N., R.J.B.); Charles River Laboratories, Kuopio, Finland (K.L., J.P., T.A.); Mass Spectrometry Center, Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland (M.A.K., J.W.J.); and Jain Foundation, Seattle, Washington (H.P.W., B.A.W., D.E.A.)
| | - Sankeerth Manne
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland (A.F.C., J.G., S.M., A.O'N., R.J.B.); Charles River Laboratories, Kuopio, Finland (K.L., J.P., T.A.); Mass Spectrometry Center, Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland (M.A.K., J.W.J.); and Jain Foundation, Seattle, Washington (H.P.W., B.A.W., D.E.A.)
| | - Andrea O'Neill
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland (A.F.C., J.G., S.M., A.O'N., R.J.B.); Charles River Laboratories, Kuopio, Finland (K.L., J.P., T.A.); Mass Spectrometry Center, Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland (M.A.K., J.W.J.); and Jain Foundation, Seattle, Washington (H.P.W., B.A.W., D.E.A.)
| | - Hillarie P Windish
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland (A.F.C., J.G., S.M., A.O'N., R.J.B.); Charles River Laboratories, Kuopio, Finland (K.L., J.P., T.A.); Mass Spectrometry Center, Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland (M.A.K., J.W.J.); and Jain Foundation, Seattle, Washington (H.P.W., B.A.W., D.E.A.)
| | - Toni Ahtoniemi
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland (A.F.C., J.G., S.M., A.O'N., R.J.B.); Charles River Laboratories, Kuopio, Finland (K.L., J.P., T.A.); Mass Spectrometry Center, Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland (M.A.K., J.W.J.); and Jain Foundation, Seattle, Washington (H.P.W., B.A.W., D.E.A.)
| | - Bradley A Williams
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland (A.F.C., J.G., S.M., A.O'N., R.J.B.); Charles River Laboratories, Kuopio, Finland (K.L., J.P., T.A.); Mass Spectrometry Center, Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland (M.A.K., J.W.J.); and Jain Foundation, Seattle, Washington (H.P.W., B.A.W., D.E.A.)
| | - Douglas E Albrecht
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland (A.F.C., J.G., S.M., A.O'N., R.J.B.); Charles River Laboratories, Kuopio, Finland (K.L., J.P., T.A.); Mass Spectrometry Center, Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland (M.A.K., J.W.J.); and Jain Foundation, Seattle, Washington (H.P.W., B.A.W., D.E.A.)
| | - Robert J Bloch
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland (A.F.C., J.G., S.M., A.O'N., R.J.B.); Charles River Laboratories, Kuopio, Finland (K.L., J.P., T.A.); Mass Spectrometry Center, Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland (M.A.K., J.W.J.); and Jain Foundation, Seattle, Washington (H.P.W., B.A.W., D.E.A.)
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22
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Desmond PF, Labuza A, Muriel J, Markwardt ML, Mancini AE, Rizzo MA, Bloch RJ. Interactions between small ankyrin 1 and sarcolipin coordinately regulate activity of the sarco(endo)plasmic reticulum Ca 2+-ATPase (SERCA1). J Biol Chem 2017; 292:10961-10972. [PMID: 28487373 PMCID: PMC5491780 DOI: 10.1074/jbc.m117.783613] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [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: 02/28/2017] [Revised: 05/08/2017] [Indexed: 11/06/2022] Open
Abstract
SERCA1, the sarco(endo)plasmic reticulum Ca2+-ATPase of skeletal muscle, is essential for muscle relaxation and maintenance of low resting Ca2+ levels in the myoplasm. We recently reported that small ankyrin 1 (sAnk1) interacts with the sarco(endo)plasmic reticulum Ca2+-ATPase in skeletal muscle (SERCA1) to inhibit its activity. We also showed that this interaction is mediated at least in part through sAnk1's transmembrane domain in a manner similar to that of sarcolipin (SLN). Earlier studies have shown that SLN and phospholamban, the other well studied small SERCA-regulatory proteins, oligomerize either alone or together. As sAnk1 is coexpressed with SLN in muscle, we sought to determine whether these two proteins interact with one another when coexpressed exogenously in COS7 cells. Coimmunoprecipitation (coIP) and anisotropy-based FRET (AFRET) assays confirmed this interaction. Our results indicated that sAnk1 and SLN can associate in the sarcoplasmic reticulum membrane and after exogenous expression in COS7 cells in vitro but that their association did not require endogenous SERCA2. Significantly, SLN promoted the interaction between sAnk1 and SERCA1 when the three proteins were coexpressed, and both coIP and AFRET experiments suggested the formation of a complex consisting of all three proteins. Ca2+-ATPase assays showed that sAnk1 ablated SLN's inhibition of SERCA1 activity. These results suggest that sAnk1 interacts with SLN both directly and in complex with SERCA1 and reduces SLN's inhibitory effect on SERCA1 activity.
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Affiliation(s)
- Patrick F Desmond
- From the Department of Physiology and
- Programs in Biochemistry and Molecular Biology
| | - Amanda Labuza
- From the Department of Physiology and
- Neuroscience, and
| | | | | | - Allison E Mancini
- Molecular Medicine, University of Maryland, Baltimore, Maryland 21201
| | - Megan A Rizzo
- From the Department of Physiology and
- Neuroscience, and
- Molecular Medicine, University of Maryland, Baltimore, Maryland 21201
| | - Robert J Bloch
- From the Department of Physiology and
- Programs in Biochemistry and Molecular Biology
- Neuroscience, and
- Molecular Medicine, University of Maryland, Baltimore, Maryland 21201
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23
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Lukyanenko V, Muriel JM, Bloch RJ. Coupling of excitation to Ca 2+ release is modulated by dysferlin. J Physiol 2017; 595:5191-5207. [PMID: 28568606 DOI: 10.1113/jp274515] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [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: 04/18/2017] [Accepted: 05/16/2017] [Indexed: 12/16/2022] Open
Abstract
KEY POINTS Dysferlin, the protein missing in limb girdle muscular dystrophy 2B and Miyoshi myopathy, concentrates in transverse tubules of skeletal muscle, where it stabilizes voltage-induced Ca2+ transients against loss after osmotic shock injury (OSI). Local expression of dysferlin in dysferlin-null myofibres increases transient amplitude to control levels and protects them from loss after OSI. Inhibitors of ryanodine receptors (RyR1) and L-type Ca2+ channels protect voltage-induced Ca2+ transients from loss; thus both proteins play a role in injury in dysferlin's absence. Effects of Ca2+ -free medium and S107, which inhibits SR Ca2+ leak, suggest the SR as the primary source of Ca2+ responsible for the loss of the Ca2+ transient upon injury. Ca2+ waves were induced by OSI and suppressed by exogenous dysferlin. We conclude that dysferlin prevents injury-induced SR Ca2+ leak. ABSTRACT Dysferlin concentrates in the transverse tubules of skeletal muscle and stabilizes Ca2+ transients when muscle fibres are subjected to osmotic shock injury (OSI). We show here that voltage-induced Ca2+ transients elicited in dysferlin-null A/J myofibres were smaller than control A/WySnJ fibres. Regional expression of Venus-dysferlin chimeras in A/J fibres restored the full amplitude of the Ca2+ transients and protected against OSI. We also show that drugs that target ryanodine receptors (RyR1: dantrolene, tetracaine, S107) and L-type Ca2+ channels (LTCCs: nifedipine, verapamil, diltiazem) prevented the decrease in Ca2+ transients in A/J fibres following OSI. Diltiazem specifically increased transients by ∼20% in uninjured A/J fibres, restoring them to control values. The fact that both RyR1s and LTCCs were involved in OSI-induced damage suggests that damage is mediated by increased Ca2+ leak from the sarcoplasmic reticulum (SR) through the RyR1. Congruent with this, injured A/J fibres produced Ca2+ sparks and Ca2+ waves. S107 (a stabilizer of RyR1-FK506 binding protein coupling that reduces Ca2+ leak) or local expression of Venus-dysferlin prevented OSI-induced Ca2+ waves. Our data suggest that dysferlin modulates SR Ca2+ release in skeletal muscle, and that in its absence OSI causes increased RyR1-mediated Ca2+ leak from the SR into the cytoplasm.
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Affiliation(s)
- Valeriy Lukyanenko
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Joaquin M Muriel
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Robert J Bloch
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
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24
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Moorer MC, Buo AM, Garcia-Pelagio KP, Stains JP, Bloch RJ. Deficiency of the intermediate filament synemin reduces bone mass in vivo. Am J Physiol Cell Physiol 2016; 311:C839-C845. [PMID: 27605453 DOI: 10.1152/ajpcell.00218.2016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 09/06/2016] [Indexed: 12/31/2022]
Abstract
While the type IV intermediate filament protein, synemin, has been shown to play a role in striated muscle and neuronal tissue, its presence and function have not been described in skeletal tissue. Here, we report that genetic ablation of synemin in 14-wk-old male mice results in osteopenia that includes a more than 2-fold reduction in the trabecular bone fraction in the distal femur and a reduction in the cross-sectional area at the femoral middiaphysis due to an attendant reduction in both the periosteal and endosteal perimeter. Analysis of serum markers of bone formation and static histomorphometry revealed a statistically significant defect in osteoblast activity and osteoblast number in vivo. Interestingly, primary osteoblasts isolated from synemin-null mice demonstrate markedly enhanced osteogenic capacity with a concomitant reduction in cyclin D1 mRNA expression, which may explain the loss of osteoblast number observed in vivo. In total, these data suggest an important, previously unknown role for synemin in bone physiology.
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Affiliation(s)
- Megan C Moorer
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, Maryland; and
| | - Atum M Buo
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, Maryland; and
| | - Karla P Garcia-Pelagio
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Joseph P Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, Maryland; and
| | - Robert J Bloch
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
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25
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Lukyanenko V, Muriel J, Bloch RJ. Dysferlin Stabilizes Excitation-Contraction Coupling in Murine Skeletal Myofibers. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.3138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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26
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Desmond PF, Muriel J, Markwardt ML, Rizzo MA, Bloch RJ. Identification of Small Ankyrin 1 as a Novel Sarco(endo)plasmic Reticulum Ca2+-ATPase 1 (SERCA1) Regulatory Protein in Skeletal Muscle. J Biol Chem 2015; 290:27854-67. [PMID: 26405035 DOI: 10.1074/jbc.m115.676585] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [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: 07/02/2015] [Indexed: 01/06/2023] Open
Abstract
Small ankyrin 1 (sAnk1) is a 17-kDa transmembrane (TM) protein that binds to the cytoskeletal protein, obscurin, and stabilizes the network sarcoplasmic reticulum in skeletal muscle. We report that sAnk1 shares homology in its TM amino acid sequence with sarcolipin, a small protein inhibitor of the sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA). Here we investigate whether sAnk1 and SERCA1 interact. Our results indicate that sAnk1 interacts specifically with SERCA1 in sarcoplasmic reticulum vesicles isolated from rabbit skeletal muscle, and in COS7 cells transfected to express these proteins. This interaction was demonstrated by co-immunoprecipitation and an anisotropy-based FRET method. Binding was reduced ~2-fold by the replacement of all of the TM amino acids of sAnk1 with leucines by mutagenesis. This suggests that, like sarcolipin, sAnk1 interacts with SERCA1 at least in part via its TM domain. Binding of the cytoplasmic domain of sAnk1 to SERCA1 was also detected in vitro. ATPase activity assays show that co-expression of sAnk1 with SERCA1 leads to a reduction of the apparent Ca(2+) affinity of SERCA1 but that the effect of sAnk1 is less than that of sarcolipin. The sAnk1 TM mutant has no effect on SERCA1 activity. Our results suggest that sAnk1 interacts with SERCA1 through its TM and cytoplasmic domains to regulate SERCA1 activity and modulate sequestration of Ca(2+) in the sarcoplasmic reticulum lumen. The identification of sAnk1 as a novel regulator of SERCA1 has significant implications for muscle physiology and the development of therapeutic approaches to treat heart failure and muscular dystrophies linked to Ca(2+) misregulation.
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Affiliation(s)
- Patrick F Desmond
- From the Department of Physiology and Program in Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland 21230
| | | | | | | | - Robert J Bloch
- From the Department of Physiology and Program in Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland 21230
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27
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Roche JA, Tulapurkar ME, Mueller AL, van Rooijen N, Hasday JD, Lovering RM, Bloch RJ. Myofiber damage precedes macrophage infiltration after in vivo injury in dysferlin-deficient A/J mouse skeletal muscle. Am J Pathol 2015; 185:1686-98. [PMID: 25920768 PMCID: PMC4450316 DOI: 10.1016/j.ajpath.2015.02.020] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Revised: 12/31/2014] [Accepted: 02/12/2015] [Indexed: 12/16/2022]
Abstract
Mutations in the dysferlin gene (DYSF) lead to human muscular dystrophies known as dysferlinopathies. The dysferlin-deficient A/J mouse develops a mild myopathy after 6 months of age, and when younger models the subclinical phase of the human disease. We subjected the tibialis anterior muscle of 3- to 4-month-old A/J mice to in vivo large-strain injury (LSI) from lengthening contractions and studied the progression of torque loss, myofiber damage, and inflammation afterward. We report that myofiber damage in A/J mice occurs before inflammatory cell infiltration. Peak edema and inflammation, monitored by magnetic resonance imaging and by immunofluorescence labeling of neutrophils and macrophages, respectively, develop 24 to 72 hours after LSI, well after the appearance of damaged myofibers. Cytokine profiles 72 hours after injury are consistent with extensive macrophage infiltration. Dysferlin-sufficient A/WySnJ mice show much less myofiber damage and inflammation and lesser cytokine levels after LSI than do A/J mice. Partial suppression of macrophage infiltration by systemic administration of clodronate-incorporated liposomes fails to suppress LSI-induced damage or to accelerate torque recovery in A/J mice. The findings from our studies suggest that, although macrophage infiltration is prominent in dysferlin-deficient A/J muscle after LSI, it is the consequence and not the cause of progressive myofiber damage.
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Affiliation(s)
- Joseph A Roche
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, Maryland.
| | - Mohan E Tulapurkar
- Department of Medicine, School of Medicine, University of Maryland, Baltimore, Maryland
| | - Amber L Mueller
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, Maryland
| | - Nico van Rooijen
- Clodronateliposomes.com, Amsterdam, the Netherlands; Department of Molecular Cell Biology, Faculty of Medicine, VU University Medical Center, Amsterdam, the Netherlands
| | - Jeffrey D Hasday
- Department of Medicine, School of Medicine, University of Maryland, Baltimore, Maryland
| | - Richard M Lovering
- Department of Orthopaedics, School of Medicine, University of Maryland, Baltimore, Maryland
| | - Robert J Bloch
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, Maryland
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García-Pelagio KP, Muriel J, O'Neill A, Desmond PF, Lovering RM, Lund L, Bond M, Bloch RJ. Myopathic changes in murine skeletal muscle lacking synemin. Am J Physiol Cell Physiol 2015; 308:C448-62. [PMID: 25567810 DOI: 10.1152/ajpcell.00331.2014] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [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: 01/24/2023]
Abstract
Diseases of striated muscle linked to intermediate filament (IF) proteins are associated with defects in the organization of the contractile apparatus and its links to costameres, which connect the sarcomeres to the cell membrane. Here we study the role in skeletal muscle of synemin, a type IV IF protein, by examining mice null for synemin (synm-null). Synm-null mice have a mild skeletal muscle phenotype. Tibialis anterior (TA) muscles show a significant decrease in mean fiber diameter, a decrease in twitch and tetanic force, and an increase in susceptibility to injury caused by lengthening contractions. Organization of proteins associated with the contractile apparatus and costameres is not significantly altered in the synm-null. Elastimetry of the sarcolemma and associated contractile apparatus in extensor digitorum longus myofibers reveals a reduction in tension consistent with an increase in sarcolemmal deformability. Although fatigue after repeated isometric contractions is more marked in TA muscles of synm-null mice, the ability of the mice to run uphill on a treadmill is similar to controls. Our results suggest that synemin contributes to linkage between costameres and the contractile apparatus and that the absence of synemin results in decreased fiber size and increased sarcolemmal deformability and susceptibility to injury. Thus synemin plays a moderate but distinct role in fast twitch skeletal muscle.
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Affiliation(s)
- Karla P García-Pelagio
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, Maryland
| | - Joaquin Muriel
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, Maryland
| | - Andrea O'Neill
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, Maryland
| | - Patrick F Desmond
- Program in Biochemistry and Molecular Biology, School of Medicine, University of Maryland, Baltimore, Maryland
| | - Richard M Lovering
- Department of Orthopaedics, School of Medicine, University of Maryland, Baltimore, Maryland
| | - Linda Lund
- Merrick School of Business, University of Baltimore, Baltimore, Maryland; and
| | - Meredith Bond
- College of Sciences and Health Professions, Cleveland State University, Cleveland, Ohio
| | - Robert J Bloch
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, Maryland;
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Abstract
Duchenne muscular dystrophy (DMD) is a severe muscle wasting disorder caused by mutations in the dystrophin gene. To examine the influence of muscle structure on the pathogenesis of DMD we generated mdx4cv:desmin double knockout (dko) mice. The dko male mice died of apparent cardiorespiratory failure at a median age of 76 days compared to 609 days for the desmin−/− mice. An ∼2.5 fold increase in utrophin expression in the dko skeletal muscles prevented necrosis in ∼91% of 1a, 2a and 2d/x fiber-types. In contrast, utrophin expression was reduced in the extrasynaptic sarcolemma of the dko fast 2b fibers leading to increased membrane fragility and dystrophic pathology. Despite lacking extrasynaptic utrophin, the dko fast 2b fibers were less dystrophic than the mdx4cv fast 2b fibers suggesting utrophin-independent mechanisms were also contributing to the reduced dystrophic pathology. We found no overt change in the regenerative capacity of muscle stem cells when comparing the wild-type, desmin−/−, mdx4cv and dko gastrocnemius muscles injured with notexin. Utrophin could form costameric striations with α-sarcomeric actin in the dko to maintain the integrity of the membrane, but the lack of restoration of the NODS (nNOS, α-dystrobrevin 1 and 2, α1-syntrophin) complex and desmin coincided with profound changes to the sarcomere alignment in the diaphragm, deposition of collagen between the myofibers, and impaired diaphragm function. We conclude that the dko mice may provide new insights into the structural mechanisms that influence endogenous utrophin expression that are pertinent for developing a therapy for DMD. Duchenne muscular dystrophy (DMD) is a severe muscle wasting disorder caused by mutations in the dystrophin gene. Utrophin is structurally similar to dystrophin and improving its expression can prevent skeletal muscle necrosis in the mdx mouse model of DMD. Consequently, improving utrophin expression is a primary therapeutic target for treating DMD. While the downstream mechanisms that influence utrophin expression and stability are well described, the upstream mechanisms are less clear. Here, we found that perturbing the highly ordered structure of striated muscle by genetically deleting desmin from mdx mice increased utrophin expression to levels that prevented skeletal muscle necrosis. Thus, the mdx:desmin double knockout mice may prove valuable in determining the upstream mechanisms that influence utrophin expression to develop a therapy for DMD.
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Affiliation(s)
- Glen B. Banks
- Department of Neurology, University of Washington, Seattle, Washington, United States of America
- * E-mail:
| | - Ariana C. Combs
- Department of Neurology, University of Washington, Seattle, Washington, United States of America
| | - Guy L. Odom
- Department of Neurology, University of Washington, Seattle, Washington, United States of America
| | - Robert J. Bloch
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Jeffrey S. Chamberlain
- Department of Neurology, University of Washington, Seattle, Washington, United States of America
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30
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Abstract
The class of muscular dystrophies linked to the genetic ablation or mutation of dysferlin, including Limb Girdle Muscular Dystrophy 2B (LGMD2B) and Miyoshi Myopathy (MM), are late-onset degenerative diseases. In lieu of a genetic cure, treatments to prevent or slow the progression of dysferlinopathy are of the utmost importance. Recent advances in the study of dysferlinopathy have highlighted the necessity for the maintenance of calcium handling in altering or slowing the progression of muscular degeneration resulting from the loss of dysferlin. This review highlights new evidence for a role for dysferlin at the transverse (t-) tubule of striated muscle, where it is involved in maintaining t-tubule structure and function.
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Affiliation(s)
- Jaclyn P Kerr
- Department of Physiology, University of Maryland School of Medicine Baltimore, MD, USA
| | - Christopher W Ward
- Department of Organizational Systems and Adult Health, University of Maryland School of Nursing Baltimore, MD, USA
| | - Robert J Bloch
- Department of Physiology, University of Maryland School of Medicine Baltimore, MD, USA
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Roche JA, Mueller AL, Bloch RJ. Large‐strain
In Vivo
Lengthening Contractions Induce Mitochondrially‐mediated Apoptosis in Dysferlin‐null Muscle. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.940.17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Joseph A Roche
- PhysiologyUniversity of Maryland School of MedicineBaltimoreMD
| | - Amber L Mueller
- PhysiologyUniversity of Maryland School of MedicineBaltimoreMD
| | - Robert J Bloch
- PhysiologyUniversity of Maryland School of MedicineBaltimoreMD
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Abstract
We describe improved methods for large format, two-dimensional gel electrophoresis (2DE) that improve protein solubility and recovery, minimize proteolysis, and reduce the loss of resolution due to contaminants and manipulations of the gels, and thus enhance quantitative analysis of protein spots. Key modifications are: (i) the use of 7 M urea and 2 M thiourea, instead of 9 M urea, in sample preparation and in the tops of the gel tubes; (ii) standardized deionization of all solutions containing urea with a mixed bed ion exchange resin and removal of urea from the electrode solutions; and (iii) use of a new gel tank and cooling device that eliminate the need to run two separating gels in the SDS dimension. These changes make 2DE analysis more reproducible and sensitive, with minimal artifacts. Application of this method to the soluble fraction of muscle tissues reliably resolves ~1800 protein spots in adult human skeletal muscle and over 2800 spots in myotubes.
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Affiliation(s)
- Patrick W Reed
- The Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, Department of Physiology, University of Maryland School of Medicine University of Maryland, Baltimore, MD 21201, USA.
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Abstract
Abstract Small ankyrin-1 is a splice variant of the ANK1 gene that binds to obscurin A. Previous studies have identified electrostatic interactions that contribute to this interaction. In addition, molecular dynamics (MD) simulations predict four hydrophobic residues in a 'hot spot' on the surface of the ankyrin-like repeats of sAnk1, near the charged residues involved in binding. We used site-directed mutagenesis, blot overlays and surface plasmon resonance assays to study the contribution of the hydrophobic residues, V70, F71, I102 and I103, to two different 30-mers of obscurin that bind sAnk1, Obsc₆₃₁₆₋₆₃₄₅ and Obsc₆₂₃₁₋₆₂₆₀. Alanine mutations of each of the hydrophobic residues disrupted binding to the high affinity binding site, Obsc₆₃₁₆₋₆₃₄₅. In contrast, V70A and I102A mutations had no effect on binding to the lower affinity site, Obsc₆₂₃₁₋₆₂₆₀. Alanine mutagenesis of the five hydrophobic residues present in Obsc₆₃₁₆₋₆₃₄₅ showed that V6328, I6332, and V6334 were critical to sAnk1 binding. Individual alanine mutants of the six hydrophobic residues of Obsc₆₂₃₁₋₆₂₆₀ had no effect on binding to sAnk1, although a triple alanine mutant of residues V6233/I6234/I6235 decreased binding. We also examined a model of the Obsc₆₃₁₆₋₆₃₄₅-sAnk1 complex in MD simulations and found I102 of sAnk1 to be within 2.2Å of V6334 of Obsc₆₃₁₆₋₆₃₄₅. In contrast to the I102A mutation, mutating I102 of sAnk1 to other hydrophobic amino acids such as phenylalanine or leucine did not disrupt binding to obscurin. Our results suggest that hydrophobic interactions contribute to the higher affinity of Obsc₆₃₁₆₋₆₃₄₅ for sAnk1 and to the dominant role exhibited by this sequence in binding.
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Affiliation(s)
- Chris D Willis
- Program in Biochemistry and Molecular Biology, University of Maryland, Baltimore, Baltimore, MD, USA
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Lostal W, Bartoli M, Roudaut C, Bourg N, Krahn M, Pryadkina M, Borel P, Suel L, Roche JA, Stockholm D, Bloch RJ, Levy N, Bashir R, Richard I. Lack of correlation between outcomes of membrane repair assay and correction of dystrophic changes in experimental therapeutic strategy in dysferlinopathy. PLoS One 2012; 7:e38036. [PMID: 22666441 PMCID: PMC3362551 DOI: 10.1371/journal.pone.0038036] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Accepted: 04/30/2012] [Indexed: 01/31/2023] Open
Abstract
Mutations in the dysferlin gene are the cause of Limb-girdle Muscular Dystrophy type 2B and Miyoshi Myopathy. The dysferlin protein has been implicated in sarcolemmal resealing, leading to the idea that the pathophysiology of dysferlin deficiencies is due to a deficit in membrane repair. Here, we show using two different approaches that fullfiling membrane repair as asseyed by laser wounding assay is not sufficient for alleviating the dysferlin deficient pathology. First, we generated a transgenic mouse overexpressing myoferlin to test the hypothesis that myoferlin, which is homologous to dysferlin, can compensate for the absence of dysferlin. The myoferlin overexpressors show no skeletal muscle abnormalities, and crossing them with a dysferlin-deficient model rescues the membrane fusion defect present in dysferlin-deficient mice in vitro. However, myoferlin overexpression does not correct muscle histology in vivo. Second, we report that AAV-mediated transfer of a minidysferlin, previously shown to correct the membrane repair deficit in vitro, also fails to improve muscle histology. Furthermore, neither myoferlin nor the minidysferlin prevented myofiber degeneration following eccentric exercise. Our data suggest that the pathogenicity of dysferlin deficiency is not solely related to impairment in sarcolemmal repair and highlight the care needed in selecting assays to assess potential therapies for dysferlinopathies.
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Affiliation(s)
| | - Marc Bartoli
- Département de Génétique Médicale, Hôpital d’Enfants de la Timone, AP-HM, and Inserm UMR_S 910, Faculté de Médecine Timone, Université de la Méditerranée, Marseille, France
| | | | | | - Martin Krahn
- Département de Génétique Médicale, Hôpital d’Enfants de la Timone, AP-HM, and Inserm UMR_S 910, Faculté de Médecine Timone, Université de la Méditerranée, Marseille, France
| | | | | | | | - Joseph A. Roche
- Department of Physiology, University of Maryland, School of Medicine, Baltimore, Maryland, United States of America
| | | | - Robert J. Bloch
- Department of Physiology, University of Maryland, School of Medicine, Baltimore, Maryland, United States of America
| | - Nicolas Levy
- Département de Génétique Médicale, Hôpital d’Enfants de la Timone, AP-HM, and Inserm UMR_S 910, Faculté de Médecine Timone, Université de la Méditerranée, Marseille, France
| | - Rumaisa Bashir
- School of Biological and Biomedical Sciences, University of Durham, Durham, United Kingdom
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Goodall MH, Ward CW, Pratt SJP, Bloch RJ, Lovering RM. Structural and functional evaluation of branched myofibers lacking intermediate filaments. Am J Physiol Cell Physiol 2012; 303:C224-32. [PMID: 22592402 DOI: 10.1152/ajpcell.00136.2012] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Intermediate filaments (IFs), composed of desmin and keratins, link myofibrils to each other and to the sarcolemma in skeletal muscle. Fast-twitch muscle of mice lacking the IF proteins, desmin and keratin 19 (K19), showed reduced specific force and increased susceptibility to injury in earlier studies. Here we tested the hypothesis that the number of malformed myofibers in mice lacking desmin (Des(-/-)), keratin 19 (K19(-/-)), or both IF proteins (double knockout, DKO) is increased and is coincident with altered excitation-contraction (EC) coupling Ca(2+) kinetics, as reported for mdx mice. We quantified the number of branched myofibers, characterized their organization with confocal and electron microscopy (EM), and compared the Ca(2+) kinetics of EC coupling in flexor digitorum brevis myofibers from adult Des(-/-), K19(-/-), or DKO mice and compared them to age-matched wild type (WT) and mdx myofibers. Consistent with our previous findings, 9.9% of mdx myofibers had visible malformations. Des(-/-) myofibers had more malformations (4.7%) than K19(-/-) (0.9%) or DKO (1.3%) myofibers. Confocal and EM imaging revealed no obvious changes in sarcomere misalignment at the branch points, and the neuromuscular junctions in the mutant mice, while more variably located, were limited to one per myofiber. Global, electrically evoked Ca(2+) signals showed a decrease in the rate of Ca(2+) uptake (decay rate) into the sarcoplasmic reticulum after Ca(2+) release, with the most profound effect in branched DKO myofibers (44% increase in uptake relative to WT). Although branched DKO myofibers showed significantly faster rates of Ca(2+) clearance, the milder branching phenotype observed in DKO muscle suggests that the absence of K19 corrects the defect created by the absence of desmin alone. Thus, there are complex roles for desmin-based and K19-based IFs in skeletal muscle, with the null and DKO mutations having different effects on Ca(2+) reuptake and myofiber branching.
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Affiliation(s)
- Mariah H Goodall
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, 21201, USA
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36
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Roche JA, Resneck WG, Mueller AL, Bloch RJ. Dysferlin maintains the integrity of transverse tubules and the junctional sarcoplasmic reticulum following contraction‐induced injury. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.1141.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Joseph A Roche
- PhysiologyUniversity of Maryland School of MedicineBaltimoreMD
| | - Wendy G Resneck
- PhysiologyUniversity of Maryland School of MedicineBaltimoreMD
| | - Amber L Mueller
- PhysiologyUniversity of Maryland School of MedicineBaltimoreMD
| | - Robert J Bloch
- PhysiologyUniversity of Maryland School of MedicineBaltimoreMD
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37
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Ziman AP, Roche J, Kerr J, Bloch RJ. Altered Skeletal Muscle Excitation Contraction Coupling in Dysferlinopathy. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.1710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022] Open
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Roche JA, Ru LW, O'Neill AM, Resneck WG, Lovering RM, Bloch RJ. Unmasking potential intracellular roles for dysferlin through improved immunolabeling methods. J Histochem Cytochem 2011; 59:964-75. [PMID: 22043020 DOI: 10.1369/0022155411423274] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mutations in the DYSF gene that severely reduce the levels of the protein dysferlin are implicated in muscle-wasting syndromes known as dysferlinopathies. Although studies of its function in skeletal muscle have focused on its potential role in repairing the plasma membrane, dysferlin has also been found, albeit inconsistently, in the sarcoplasm of muscle fibers. The aim of this article is to study the localization of dysferlin in skeletal muscle through optimized immunolabeling methods. We studied the localization of dysferlin in control rat skeletal muscle using several different methods of tissue collection and subsequent immunolabeling. We then applied our optimized immunolabeling methods on human cadaveric muscle, control and dystrophic human muscle biopsies, and control and dysferlin-deficient mouse muscle. Our data suggest that dysferlin is present in a reticulum of the sarcoplasm, similar but not identical to those containing the dihydropyridine receptors and distinct from the distribution of the sarcolemmal protein dystrophin. Our data illustrate the importance of tissue fixation and antigen unmasking for proper immunolocalization of dysferlin. They suggest that dysferlin has an important function in the internal membrane systems of skeletal muscle, involved in calcium homeostasis and excitation-contraction coupling.
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Affiliation(s)
- Joseph A Roche
- Department of Physiology, University of Maryland School of Medicine, Baltimore, USA
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39
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Ackermann MA, Ziman AP, Strong J, Zhang Y, Hartford AK, Ward CW, Randall WR, Kontrogianni-Konstantopoulos A, Bloch RJ. Integrity of the network sarcoplasmic reticulum in skeletal muscle requires small ankyrin 1. J Cell Sci 2011; 124:3619-30. [PMID: 22045734 PMCID: PMC3215573 DOI: 10.1242/jcs.085159] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [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] [Accepted: 06/06/2011] [Indexed: 01/16/2023] Open
Abstract
Small ankyrin 1 (sAnk1; Ank1.5) is a ~20 kDa protein of striated muscle that concentrates in the network compartment of the sarcoplasmic reticulum (nSR). We used siRNA targeted to sAnk1 to assess its role in organizing the sarcoplasmic reticulum (SR) of skeletal myofibers in vitro. siRNA reduced sAnk1 mRNA and protein levels and disrupted the organization of the remaining sAnk1. Sarcomeric proteins were unchanged, but two other proteins of the nSR, SERCA and sarcolipin, decreased significantly in amount and segregated into distinct structures containing sarcolipin and sAnk1, and SERCA, respectively. Exogenous sAnk1 restored SERCA to its normal distribution. Ryanodine receptors and calsequestrin in the junctional SR, and L-type Ca(2+) channels in the transverse tubules were not reduced, although their striated organization was mildly altered. Consistent with the loss of SERCA, uptake and release of Ca(2+) were significantly inhibited. Our results show that sAnk1 stabilizes the nSR and that its absence causes the nSR to fragment into distinct membrane compartments.
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Affiliation(s)
- Maegen A. Ackermann
- Department of Biochemistry and Molecular Biology, Therapeutics University of Maryland, Baltimore, MD 21201, USA
| | - Andrew P. Ziman
- Department of Physiology, Therapeutics University of Maryland, Baltimore, MD 21201, USA
| | - John Strong
- Department of Physiology, Therapeutics University of Maryland, Baltimore, MD 21201, USA
| | - Yinghua Zhang
- Department of Physiology, Therapeutics University of Maryland, Baltimore, MD 21201, USA
| | - April K. Hartford
- Department of Physiology, Therapeutics University of Maryland, Baltimore, MD 21201, USA
| | - Christopher W. Ward
- School of Medicine and School of Nursing Therapeutics University of Maryland, Baltimore, MD 21201, USA
| | - William R. Randall
- Department of Pharmacology and Experimental Therapeutics University of Maryland, Baltimore, MD 21201, USA
| | | | - Robert J. Bloch
- Department of Physiology, Therapeutics University of Maryland, Baltimore, MD 21201, USA
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Lund LM, Kerr JP, Lupinetti J, Zhang Y, Russell MA, Bloch RJ, Bond M. Synemin isoforms differentially organize cell junctions and desmin filaments in neonatal cardiomyocytes. FASEB J 2011; 26:137-48. [PMID: 21982947 DOI: 10.1096/fj.10-179408] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Intermediate filaments (IFs) in cardiomyocytes consist primarily of desmin, surround myofibrils at Z disks, and transmit forces from the contracting myofilaments to the cell surface through costameres at the sarcolemma and desmosomes at intercalated disks. Synemin is a type IV IF protein that forms filaments with desmin and also binds α-actinin and vinculin. Here we examine the roles and expression of the α and β forms of synemin in developing rat cardiomyocytes. Quantitative PCR showed low levels of expression for both synemin mRNAs, which peaked at postnatal day 7. Synemin was concentrated at sites of cell-cell adhesion and at Z disks in neonatal cardiomyocytes. Overexpression of the individual isoforms showed that α-synemin preferentially localized to cell-cell junctions, whereas β-synemin was primarily at the level of Z disks. An siRNA targeted to both synemin isoforms reduced protein expression in cardiomyocytes by 70% and resulted in a failure of desmin to align with Z disks and disrupted cell-cell junctions, with no effect on sarcomeric organization. Solubility assays showed that β-synemin was soluble and interacted with sarcomeric α-actinin by coimmunoprecipitation, while α-synemin and desmin were insoluble. We conclude that β-synemin mediates the association of desmin IFs with Z disks, whereas α-synemin stabilizes junctional complexes between cardiomyocytes.
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Affiliation(s)
- Linda M Lund
- Department of Physiology, University of Maryland, Baltimore, MD 21201, USA.
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41
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Roche JA, Ford-Speelman DL, Ru LW, Densmore AL, Roche R, Reed PW, Bloch RJ. Physiological and histological changes in skeletal muscle following in vivo gene transfer by electroporation. Am J Physiol Cell Physiol 2011; 301:C1239-50. [PMID: 21832248 DOI: 10.1152/ajpcell.00431.2010] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Electroporation (EP) is used to transfect skeletal muscle fibers in vivo, but its effects on the structure and function of skeletal muscle tissue have not yet been documented in detail. We studied the changes in contractile function and histology after EP and the influence of the individual steps involved to determine the mechanism of recovery, the extent of myofiber damage, and the efficiency of expression of a green fluorescent protein (GFP) transgene in the tibialis anterior (TA) muscle of adult male C57Bl/6J mice. Immediately after EP, contractile torque decreased by ∼80% from pre-EP levels. Within 3 h, torque recovered to ∼50% but stayed low until day 3. Functional recovery progressed slowly and was complete at day 28. In muscles that were depleted of satellite cells by X-irradiation, torque remained low after day 3, suggesting that myogenesis is necessary for complete recovery. In unirradiated muscle, myogenic activity after EP was confirmed by an increase in fibers with central nuclei or developmental myosin. Damage after EP was confirmed by the presence of necrotic myofibers infiltrated by CD68+ macrophages, which persisted in electroporated muscle for 42 days. Expression of GFP was detected at day 3 after EP and peaked on day 7, with ∼25% of fibers transfected. The number of fibers expressing green fluorescent protein (GFP), the distribution of GFP+ fibers, and the intensity of fluorescence in GFP+ fibers were highly variable. After intramuscular injection alone, or application of the electroporating current without injection, torque decreased by ∼20% and ∼70%, respectively, but secondary damage at D3 and later was minimal. We conclude that EP of murine TA muscles produces variable and modest levels of transgene expression, causes myofiber damage due to the interaction of intramuscular injection with the permeabilizing current, and that full recovery requires myogenesis.
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Affiliation(s)
- Joseph A Roche
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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43
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Muriel JM, Lovering RM, O'Neill A, Kerr JP, Bloch RJ. Keratin 18 Is Integral Part Of The Intermediate Filament Network In Skeletal Muscle. Med Sci Sports Exerc 2011. [DOI: 10.1249/01.mss.0000400797.56417.37] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Busby B, Oashi T, Willis CD, Ackermann MA, Kontrogianni-Konstantopoulos A, Mackerell AD, Bloch RJ. Electrostatic interactions mediate binding of obscurin to small ankyrin 1: biochemical and molecular modeling studies. J Mol Biol 2011; 408:321-34. [PMID: 21333652 DOI: 10.1016/j.jmb.2011.01.053] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Revised: 01/25/2011] [Accepted: 01/28/2011] [Indexed: 10/18/2022]
Abstract
Small ankyrin 1 (sAnk1; also known as Ank1.5) is an integral protein of the sarcoplasmic reticulum (SR) in skeletal and cardiac muscle cells, where it is thought to bind to the C-terminal region of obscurin, a large modular protein that surrounds the contractile apparatus. Using fusion proteins in vitro, in combination with site-directed mutagenesis and surface plasmon resonance measurements, we previously showed that the binding site on sAnk1 for obscurin consists, in part, of six lysine and arginine residues. Here we show that four charged residues in the high-affinity binding site on obscurin for sAnk1 (between residues 6316 and 6345), consisting of three glutamates and a lysine, are necessary, but not sufficient, for this site on obscurin to bind to sAnk1 with high affinity. We also identify specific complementary mutations in sAnk1 that can partially or completely compensate for the changes in binding caused by charge-switching mutations in obscurin. We used molecular modeling to develop structural models of residues 6322-6339 of obscurin bound to sAnk1. The models, based on a combination of Brownian and molecular dynamics simulations, predict that the binding site on sAnk1 for obscurin is organized as two ankyrin-like repeats, with the last α-helical segment oriented at an angle to nearby helices, allowing lysine 6338 of obscurin to form an ionic interaction with aspartate 111 of sAnk1. This prediction was validated by double-mutant cycle experiments. Our results are consistent with a model in which electrostatic interactions between specific pairs of side chains on obscurin and sAnk1 promote binding and complex formation.
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Affiliation(s)
- Ben Busby
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
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45
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Cappello RE, Estrada-Gutierrez G, Irles C, Giono-Cerezo S, Bloch RJ, Nataro JP. Effects of the plasmid-encoded toxin of enteroaggregative Escherichia coli on focal adhesion complexes. ACTA ACUST UNITED AC 2011; 61:301-14. [PMID: 21205005 DOI: 10.1111/j.1574-695x.2010.00776.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Enteroaggregative Escherichia coli (EAEC) is an emerging diarrheal pathogen. Many EAEC strains produce the plasmid-encoded toxin (Pet), which exerts cytotoxic effects on human intestinal tissue. Pet-intoxicated HEp-2 cells exhibit rounding and detachment from the substratum, accompanied by loss of F-actin stress fibers and condensation of the spectrin-containing membrane cytoskeleton. Although studies suggest that Pet directly cleaves spectrin, it is not known whether this is the essential mode of action of the toxin. In addition, the effects of Pet on cytoskeletal elements other than actin and spectrin have not been reported. Here, we demonstrate by immunofluorescence that upon Pet intoxication, HEp-2 and HT29 cells lose focal adhesion complexes (FAC), a process that includes the redistribution of focal adhesion kinase (FAK), α-actinin, paxillin, vinculin, F-actin, and spectrin itself. This redistribution was coupled with the depletion of phosphotyrosine labeling at FACs. Immunoblotting and immunoprecipitation experiments revealed that FAK was tyrosine dephosphorylated, before the redistribution of FAK and spectrin. Moreover, phosphatase inhibition blocked cell retraction, suggesting that tyrosine dephosphorylation is an event that precedes FAK cleavage. Finally, we show that in vitro tyrosine-dephosphorylated FAK was susceptible to Pet cleavage. These data suggest that mechanisms other than spectrin redistribution occur during Pet intoxication.
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Affiliation(s)
- Renato E Cappello
- Institutional Program in Molecular Biomedicine, National School of Homeopathy and Medicine, Instituto Politecnico Nacional, Mexico City, Mexico.
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46
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Ziman AP, Ward CW, Rodney GG, Lederer WJ, Bloch RJ. Quantitative measurement of Ca²(+) in the sarcoplasmic reticulum lumen of mammalian skeletal muscle. Biophys J 2011; 99:2705-14. [PMID: 20959112 DOI: 10.1016/j.bpj.2010.08.032] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Revised: 08/10/2010] [Accepted: 08/12/2010] [Indexed: 12/18/2022] Open
Abstract
Skeletal muscle stores Ca²(+) in the sarcoplasmic reticulum (SR) and releases it to initiate contraction, but the concentration of luminal Ca²(+) in the SR ([Ca²(+)](SR)) and the amount that is released by physiological or pharmacological stimulation has been difficult to measure. Here we present a novel, yet simple and direct, method that provides the first quantitative estimates of static content and dynamic changes in [Ca²(+)](SR) in mammalian skeletal muscle, to our knowledge. The method uses fluo-5N loaded into the SR of single, mammalian skeletal muscle cells (murine flexor digitorum brevis myofibers) and confocal imaging to detect and calibrate the signals. Using this method, we have determined that [Ca²(+)](SR, free) is 390 μM. 4-Chloro-m-cresol, an activator of the skeletal muscle ryanodine receptor, reduces [Ca²(+)](SR, free) to ∼8 μM, when values are corrected for background fluorescence from cytoplasmic pools of dye. Prolonged electrical stimulation (10 s) at 50 Hz releases 88% of the SR Ca²(+) content, whereas stimulation at 1 Hz (10 s) releases only 20%. Our results lay the foundation for molecular modeling of the dynamics of luminal SR Ca²(+) and for future studies of the role of SR Ca²(+) in healthy and diseased mammalian muscle.
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Affiliation(s)
- Andrew P Ziman
- Department of Physiology, University of Maryland, Baltimore, Maryland, USA.
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Nestor MW, Cai X, Stone MR, Bloch RJ, Thompson SM. The actin binding domain of βI-spectrin regulates the morphological and functional dynamics of dendritic spines. PLoS One 2011; 6:e16197. [PMID: 21297961 PMCID: PMC3031527 DOI: 10.1371/journal.pone.0016197] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Accepted: 12/07/2010] [Indexed: 01/30/2023] Open
Abstract
Actin microfilaments regulate the size, shape and mobility of dendritic spines and are in turn regulated by actin binding proteins and small GTPases. The βI isoform of spectrin, a protein that links the actin cytoskeleton to membrane proteins, is present in spines. To understand its function, we expressed its actin-binding domain (ABD) in CA1 pyramidal neurons in hippocampal slice cultures. The ABD of βI-spectrin bundled actin in principal dendrites and was concentrated in dendritic spines, where it significantly increased the size of the spine head. These effects were not observed after expression of homologous ABDs of utrophin, dystrophin, and α-actinin. Treatment of slice cultures with latrunculin-B significantly decreased spine head size and decreased actin-GFP fluorescence in cells expressing the ABD of α-actinin, but not the ABD of βI-spectrin, suggesting that its presence inhibits actin depolymerization. We also observed an increase in the area of GFP-tagged PSD-95 in the spine head and an increase in the amplitude of mEPSCs at spines expressing the ABD of βI-spectrin. The effects of the βI-spectrin ABD on spine size and mEPSC amplitude were mimicked by expressing wild-type Rac3, a small GTPase that co-immunoprecipitates specifically with βI-spectrin in extracts of cultured cortical neurons. Spine size was normal in cells co-expressing a dominant negative Rac3 construct with the βI-spectrin ABD. We suggest that βI-spectrin is a synaptic protein that can modulate both the morphological and functional dynamics of dendritic spines, perhaps via interaction with actin and Rac3.
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Affiliation(s)
- Michael W. Nestor
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Program in Neuroscience, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Training Program in Integrative Membrane Biology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Xiang Cai
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Michele R. Stone
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Robert J. Bloch
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Program in Neuroscience, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Training Program in Integrative Membrane Biology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Scott M. Thompson
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Program in Neuroscience, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- Training Program in Integrative Membrane Biology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- * E-mail:
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48
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Lovering RM, O'Neill A, Muriel JM, Prosser BL, Strong J, Bloch RJ. Physiology, structure, and susceptibility to injury of skeletal muscle in mice lacking keratin 19-based and desmin-based intermediate filaments. Am J Physiol Cell Physiol 2011; 300:C803-13. [PMID: 21209367 DOI: 10.1152/ajpcell.00394.2010] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Intermediate filaments, composed of desmin and of keratins, play important roles in linking contractile elements to each other and to the sarcolemma in striated muscle. Our previous results show that the tibialis anterior (TA) muscles of mice lacking keratin 19 (K19) lose costameres, accumulate mitochondria under the sarcolemma, and generate lower specific tension than controls. Here we compare the physiology and morphology of TA muscles of mice lacking K19 with muscles lacking desmin or both proteins [double knockout (DKO)]. K19-/- mice and DKO mice showed a threefold increase in the levels of creatine kinase (CK) in the serum. The absence of desmin caused a larger change in specific tension (-40%) than the absence of K19 (-19%) and played the predominant role in contractile function (-40%) and decreased tolerance to exercise in the DKO muscle. By contrast, the absence of both proteins was required to obtain a significantly greater loss of contractile torque after injury (-48%) compared with wild type (-39%), as well as near-complete disruption of costameres. The DKO muscle also showed a significantly greater misalignment of myofibrils than either mutant alone. In contrast, large subsarcolemmal gaps and extensive accumulation of mitochondria were only seen in K19-null TA muscles, and the absence of both K19 and desmin yielded milder phenotypes. Our results suggest that keratin filaments containing K19- and desmin-based intermediate filaments can play independent, complementary, or antagonistic roles in the physiology and morphology of fast-twitch skeletal muscle.
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Affiliation(s)
- Richard M Lovering
- Department of Physiology, University of Maryland, Baltimore, 21201, USA.
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Busby B, Willis CD, Ackermann MA, Kontrogianni-Konstantopoulos A, Bloch RJ. Characterization and comparison of two binding sites on obscurin for small ankyrin 1. Biochemistry 2010; 49:9948-56. [PMID: 20949908 DOI: 10.1021/bi101165p] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Obscurin A, an ∼720 kDa modular protein of striated muscles, binds to small ankyrin 1 (sAnk1, Ank 1.5), an integral protein of the sarcoplasmic reticulum, through two distinct carboxy-terminal sequences, Obsc(6316-6436) and Obsc(6236-6260). We hypothesized that these sequences differ in affinity but that they compete for the same binding site on sAnk1. We show that the sequence within Obsc(6316-6436) that binds to sAnk1 is limited to residues 6316-6345. Comparison of Obsc(6231-6260) to Obsc(6316-6345) reveals that Obsc(6316-6345) binds sAnk1 with an affinity (133 ± 43 nM) comparable to that of the Obsc(6316-6436) fusion protein, whereas Obsc(6231-6260) binds with lower affinity (384 ± 53 nM). Oligopeptides of each sequence compete for binding with both sites at half-maximal inhibitory concentrations consistent with the affinities measured directly. Five of six site-directed mutants of sAnk1 showed similar reductions in binding to each binding site on obscurin, suggesting that they dock to many of the same residues of sAnk1. Circular dichroism (CD) analysis of the synthetic oligopeptides revealed a 2-fold greater α-helical content in Obsc(6316-6346), ∼35%, than Obsc(6231-6260,) ∼17%. Using these data, structural prediction algorithms, and homology modeling, we predict that Obsc(6316-6345) contains a bent α-helix of 12 amino acids, flanked by short disordered regions, and that Obsc(6231-6260) has a short, N-terminal α-helix of 4-5 residues followed by a long disordered region. Our results are consistent with a model in which both sequences of obscurin differ significantly in structure but bind to the ankyrin-like repeat motifs of sAnk1 in a similar though not identical manner.
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Affiliation(s)
- Ben Busby
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore,Baltimore, Maryland 21201, United States
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50
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Williams MW, Bloch RJ. Erratum to: Differential distribution of dystrophin and β-spectrin at the sarcolemma of fast twitch skeletal muscle fibers. J Muscle Res Cell Motil 2010. [DOI: 10.1007/s10974-010-9217-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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