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Hua C, Slick RA, Vavra J, Muretta JM, Ervasti JM, Salapaka MV. Two operational modes of atomic force microscopy reveal similar mechanical properties for homologous regions of dystrophin and utrophin. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.18.593686. [PMID: 38826288 PMCID: PMC11142110 DOI: 10.1101/2024.05.18.593686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Duchenne muscular dystrophy (DMD) is a lethal muscle disease caused by the absence of the protein dystrophin. Dystrophin is hypothesized to work as a molecular shock absorber that limits myofiber membrane damage when undergoing reversible unfolding upon muscle stretching and contraction. Utrophin is a dystrophin homologue that is under investigation as a protein replacement therapy for DMD. However, it remains uncertain whether utrophin can mechanically substitute for dystrophin. Here, we compared the mechanical properties of homologous utrophin and dystrophin fragments encoding the N terminus through spectrin repeat 3 (UtrN-R3, DysN-R3) using two operational modes of atomic force microscopy (AFM), constant speed and constant force. Our comprehensive data, including the statistics of force magnitude at which the folded domains unfold in constant speed mode and the time of unfolding statistics in constant force mode, show consistent results. We recover parameters of the energy landscape of the domains and conducted Monte Carlo simulations which corroborate the conclusions drawn from experimental data. Our results confirm that UtrN-R3 expressed in bacteria exhibits significantly lower mechanical stiffness compared to insect UtrN-R3, while the mechanical stiffness of the homologous region of dystrophin (DysN-R3) is intermediate between bacterial and insect UtrN-R3, showing greater similarity to bacterial UtrN-R3.
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Affiliation(s)
- Cailong Hua
- Department of Electrical and Computer Engineering, University of Minnesota - Twin Cities, Minneapolis, MN
| | - Rebecca A Slick
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota - Twin Cities, Minneapolis, MN
| | - Joseph Vavra
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota - Twin Cities, Minneapolis, MN
| | - Joseph M Muretta
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota - Twin Cities, Minneapolis, MN
| | - James M Ervasti
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota - Twin Cities, Minneapolis, MN
| | - Murti V Salapaka
- Department of Electrical and Computer Engineering, University of Minnesota - Twin Cities, Minneapolis, MN
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2
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Nicolau S, Malhotra J, Kaler M, Magistrado-Coxen P, Iammarino MA, Reash NF, Frair EC, Wijeratne S, Kelly BJ, White P, Lowes LP, Waldrop MA, Flanigan KM. Increase in Full-Length Dystrophin by Exon Skipping in Duchenne Muscular Dystrophy Patients with Single Exon Duplications: An Open-label Study. J Neuromuscul Dis 2024; 11:679-685. [PMID: 38461513 PMCID: PMC11091625 DOI: 10.3233/jnd-230107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/21/2024] [Indexed: 03/12/2024]
Abstract
Single exon duplications account for disease in a minority of Duchenne muscular dystrophy patients. Exon skipping in these patients has the potential to be highly therapeutic through restoration of full-length dystrophin expression. We conducted a 48-week open label study of casimersen and golodirsen in 3 subjects with an exon 45 or 53 duplication. Two subjects (aged 18 and 23 years) were non-ambulatory at baseline. Upper limb, pulmonary, and cardiac function appeared stable in the 2 subjects in whom they could be evaluated. Dystrophin expression increased from 0.94 % ±0.59% (mean±SD) of normal to 5.1% ±2.9% by western blot. Percent dystrophin positive fibers also rose from 14% ±17% at baseline to 50% ±42% . Our results provide initial evidence that the use of exon-skipping drugs may increase dystrophin levels in patients with single-exon duplications.
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Affiliation(s)
- Stefan Nicolau
- Center for Gene Therapy, Nationwide Children’s Hospital, Columbus, OH, USA
| | | | - Maryann Kaler
- Center for Gene Therapy, Nationwide Children’s Hospital, Columbus, OH, USA
| | | | - Megan A. Iammarino
- Center for Gene Therapy, Nationwide Children’s Hospital, Columbus, OH, USA
| | - Natalie F. Reash
- Center for Gene Therapy, Nationwide Children’s Hospital, Columbus, OH, USA
| | - Emma C. Frair
- Center for Gene Therapy, Nationwide Children’s Hospital, Columbus, OH, USA
| | - Saranga Wijeratne
- Institute for Genomic Medicine, Nationwide Children’s Hospital, Columbus, OH, USA
| | - Benjamin J. Kelly
- Institute for Genomic Medicine, Nationwide Children’s Hospital, Columbus, OH, USA
| | - Peter White
- Institute for Genomic Medicine, Nationwide Children’s Hospital, Columbus, OH, USA
- Department of Pediatrics, The Ohio State University, Columbus, OH, USA
| | - Linda P. Lowes
- Center for Gene Therapy, Nationwide Children’s Hospital, Columbus, OH, USA
| | - Megan A. Waldrop
- Center for Gene Therapy, Nationwide Children’s Hospital, Columbus, OH, USA
- Department of Pediatrics, The Ohio State University, Columbus, OH, USA
- >Department of Neurology>, The Ohio State University, Columbus, OH, USA
| | - Kevin M. Flanigan
- Center for Gene Therapy, Nationwide Children’s Hospital, Columbus, OH, USA
- Department of Pediatrics, The Ohio State University, Columbus, OH, USA
- >Department of Neurology>, The Ohio State University, Columbus, OH, USA
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3
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Ramirez MP, Rajaganapathy S, Hagerty AR, Hua C, Baxter GC, Vavra J, Gordon WR, Muretta JM, Salapaka MV, Ervasti JM. Phosphorylation alters the mechanical stiffness of a model fragment of the dystrophin homologue utrophin. J Biol Chem 2023; 299:102847. [PMID: 36587764 PMCID: PMC9922815 DOI: 10.1016/j.jbc.2022.102847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 12/16/2022] [Accepted: 12/18/2022] [Indexed: 12/30/2022] Open
Abstract
Duchenne muscular dystrophy is a lethal muscle wasting disease caused by the absence of the protein dystrophin. Utrophin is a dystrophin homologue currently under investigation as a protein replacement therapy for Duchenne muscular dystrophy. Dystrophin is hypothesized to function as a molecular shock absorber that mechanically stabilizes the sarcolemma. While utrophin is homologous with dystrophin from a molecular and biochemical perspective, we have recently shown that full-length utrophin expressed in eukaryotic cells is stiffer than what has been reported for dystrophin fragments expressed in bacteria. In this study, we show that differences in expression system impact the mechanical stiffness of a model utrophin fragment encoding the N terminus through spectrin repeat 3 (UtrN-R3). We also demonstrate that UtrN-R3 expressed in eukaryotic cells was phosphorylated while bacterial UtrN-R3 was not detectably phosphorylated. Using atomic force microscopy, we show that phosphorylated UtrN-R3 exhibited significantly higher unfolding forces compared to unphosphorylated UtrN-R3 without altering its actin-binding activity. Consistent with the effect of phosphorylation on mechanical stiffness, mutating the phosphorylated serine residues on insect eukaryotic protein to alanine decreased its stiffness to levels not different from unphosphorylated bacterial protein. Taken together, our data suggest that the mechanical properties of utrophin may be tuned by phosphorylation, with the potential to improve its efficacy as a protein replacement therapy for dystrophinopathies.
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Affiliation(s)
- Maria Paz Ramirez
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota - Twin Cities, Minneapolis, MN, USA
| | - Sivaraman Rajaganapathy
- Department of Electrical and Computer Engineering, University of Minnesota - Twin Cities, Minneapolis, MN, USA
| | - Anthony R Hagerty
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota - Twin Cities, Minneapolis, MN, USA
| | - Cailong Hua
- Department of Electrical and Computer Engineering, University of Minnesota - Twin Cities, Minneapolis, MN, USA
| | - Gloria C Baxter
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota - Twin Cities, Minneapolis, MN, USA
| | - Joseph Vavra
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota - Twin Cities, Minneapolis, MN, USA
| | - Wendy R Gordon
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota - Twin Cities, Minneapolis, MN, USA
| | - Joseph M Muretta
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota - Twin Cities, Minneapolis, MN, USA
| | - Murti V Salapaka
- Department of Electrical and Computer Engineering, University of Minnesota - Twin Cities, Minneapolis, MN, USA
| | - James M Ervasti
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota - Twin Cities, Minneapolis, MN, USA.
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4
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Novak JS, Spathis R, Dang UJ, Fiorillo AA, Hindupur R, Tully CB, Mázala DA, Canessa E, Brown KJ, Partridge TA, Hathout Y, Nagaraju K. Interrogation of Dystrophin and Dystroglycan Complex Protein Turnover After Exon Skipping Therapy. J Neuromuscul Dis 2021; 8:S383-S402. [PMID: 34569969 PMCID: PMC8673539 DOI: 10.3233/jnd-210696] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Recently, the Food and Drug Administration granted accelerated approvals for four exon skipping therapies -Eteplirsen, Golodirsen, Viltolarsen, and Casimersen -for Duchenne Muscular Dystrophy (DMD). However, these treatments have only demonstrated variable and largely sub-therapeutic levels of restored dystrophin protein in DMD patients, limiting their clinical impact. To better understand variable protein expression and the behavior of truncated dystrophin protein in vivo, we assessed turnover dynamics of restored dystrophin and dystrophin glycoprotein complex (DGC) proteins in mdx mice after exon skipping therapy, compared to those dynamics in wild type mice, using a targeted, highly-reproducible and sensitive, in vivo stable isotope labeling mass spectrometry approach in multiple muscle tissues. Through statistical modeling, we found that restored dystrophin protein exhibited altered stability and slower turnover in treated mdx muscle compared with that in wild type muscle (∼44 d vs. ∼24 d, respectively). Assessment of mRNA transcript stability (quantitative real-time PCR, droplet digital PCR) and dystrophin protein expression (capillary gel electrophoresis, immunofluorescence) support our dystrophin protein turnover measurements and modeling. Further, we assessed pathology-induced muscle fiber turnover through bromodeoxyuridine (BrdU) labeling to model dystrophin and DGC protein turnover in the context of persistent fiber degeneration. Our findings reveal sequestration of restored dystrophin protein after exon skipping therapy in mdx muscle leading to a significant extension of its half-life compared to the dynamics of full-length dystrophin in normal muscle. In contrast, DGC proteins show constant turnover attributable to myofiber degeneration and dysregulation of the extracellular matrix (ECM) in dystrophic muscle. Based on our results, we demonstrate the use of targeted mass spectrometry to evaluate the suitability and functionality of restored dystrophin isoforms in the context of disease and propose its use to optimize alternative gene correction strategies in development for DMD.
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Affiliation(s)
- James S. Novak
- Center for Genetic Medicine Research, Children’sResearch Institute, Children’s National Hospital, Washington, DC, USA
- Department of Genomics and PrecisionMedicine, The George Washington University School of Medicine and Health Sciences, Washington DC, USA
- Department of Pediatrics, The George Washington University School of Medicine and Health Sciences, Washington DC, USA
- Correspondence to: James Novak, 111 Michigan Avenue NW, Washington, DC, 20010-2916 USA. Tel.: +1 202 476 6135; E-mail: . and Kanneboyina Nagaraju, PO Box 6000, Binghamton, NY, 13902-6000 USA. Tel.: +1 607 777 5814; E-mail:
| | - Rita Spathis
- School of Pharmacy and Pharmaceutical Sciences, Binghamton University, Binghamton, NY USA
| | - Utkarsh J. Dang
- School of Pharmacy and Pharmaceutical Sciences, Binghamton University, Binghamton, NY USA
- Department of Health Sciences, Carleton University, Ottawa, Ontario, Canada
| | - Alyson A. Fiorillo
- Center for Genetic Medicine Research, Children’sResearch Institute, Children’s National Hospital, Washington, DC, USA
- Department of Genomics and PrecisionMedicine, The George Washington University School of Medicine and Health Sciences, Washington DC, USA
- Department of Pediatrics, The George Washington University School of Medicine and Health Sciences, Washington DC, USA
| | - Ravi Hindupur
- Center for Genetic Medicine Research, Children’sResearch Institute, Children’s National Hospital, Washington, DC, USA
| | - Christopher B. Tully
- Center for Genetic Medicine Research, Children’sResearch Institute, Children’s National Hospital, Washington, DC, USA
| | - Davi A.G. Mázala
- Center for Genetic Medicine Research, Children’sResearch Institute, Children’s National Hospital, Washington, DC, USA
- Department of Kinesiology, College of Health Professionals, Towson University, Towson, MD, USA
| | - Emily Canessa
- School of Pharmacy and Pharmaceutical Sciences, Binghamton University, Binghamton, NY USA
| | | | - Terence A. Partridge
- Center for Genetic Medicine Research, Children’sResearch Institute, Children’s National Hospital, Washington, DC, USA
| | - Yetrib Hathout
- School of Pharmacy and Pharmaceutical Sciences, Binghamton University, Binghamton, NY USA
| | - Kanneboyina Nagaraju
- Department of Genomics and PrecisionMedicine, The George Washington University School of Medicine and Health Sciences, Washington DC, USA
- School of Pharmacy and Pharmaceutical Sciences, Binghamton University, Binghamton, NY USA
- Correspondence to: James Novak, 111 Michigan Avenue NW, Washington, DC, 20010-2916 USA. Tel.: +1 202 476 6135; E-mail: . and Kanneboyina Nagaraju, PO Box 6000, Binghamton, NY, 13902-6000 USA. Tel.: +1 607 777 5814; E-mail:
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Teramoto N, Sugihara H, Yamanouchi K, Nakamura K, Kimura K, Okano T, Shiga T, Shirakawa T, Matsuo M, Nagata T, Daimon M, Matsuwaki T, Nishihara M. Pathological evaluation of rats carrying in-frame mutations in the dystrophin gene: a new model of Becker muscular dystrophy. Dis Model Mech 2020; 13:dmm044701. [PMID: 32859695 PMCID: PMC7541341 DOI: 10.1242/dmm.044701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 08/18/2020] [Indexed: 01/10/2023] Open
Abstract
Dystrophin, encoded by the DMD gene on the X chromosome, stabilizes the sarcolemma by linking the actin cytoskeleton with the dystrophin-glycoprotein complex (DGC). In-frame mutations in DMD cause a milder form of X-linked muscular dystrophy, called Becker muscular dystrophy (BMD), characterized by the reduced expression of truncated dystrophin. So far, no animal model with in-frame mutations in Dmd has been established. As a result, the effect of in-frame mutations on the dystrophin expression profile and disease progression of BMD remains unclear. In this study, we established a novel rat model carrying in-frame Dmd gene mutations (IF rats) and evaluated the pathology. We found that IF rats exhibited reduced expression of truncated dystrophin in a proteasome-independent manner. This abnormal dystrophin expression caused dystrophic changes in muscle tissues but did not lead to functional deficiency. We also found that the expression of additional dystrophin named dpX, which forms the DGC in the sarcolemma, was associated with the appearance of truncated dystrophin. In conclusion, the outcomes of this study contribute to the further understanding of BMD pathology and help elucidate the efficiency of dystrophin recovery treatments in Duchenne muscular dystrophy, a more severe form of X-linked muscular dystrophy.
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Affiliation(s)
- Naomi Teramoto
- Department of Veterinary Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Hidetoshi Sugihara
- Department of Veterinary Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Keitaro Yamanouchi
- Department of Veterinary Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Katsuyuki Nakamura
- Department of Veterinary Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Koichi Kimura
- Department of General Medicine, The Institute of Medical Science, The University of Tokyo, Minato-ku, Tokyo, 108-8639, Japan
- Department of Cardiovascular Medicine, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Tomoko Okano
- Department of Laboratory Medicine, The University of Tokyo Hospital, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Takanori Shiga
- Department of Veterinary Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Taku Shirakawa
- Research Center for Locomotion Biology, Kobe Gakuin University, Nishi, Kobe, 651-2180, Japan
- KNC Department of Nucleic Acid Drug Discovery, Faculty of Rehabilitation, Kobe Gakuin University, Nishi, Kobe, 651-2180, Japan
| | - Masafumi Matsuo
- Research Center for Locomotion Biology, Kobe Gakuin University, Nishi, Kobe, 651-2180, Japan
- KNC Department of Nucleic Acid Drug Discovery, Faculty of Rehabilitation, Kobe Gakuin University, Nishi, Kobe, 651-2180, Japan
| | - Tetsuya Nagata
- Department of Neurology and Neurological Science, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Masao Daimon
- Department of Laboratory Medicine, The University of Tokyo Hospital, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Takashi Matsuwaki
- Department of Veterinary Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Masugi Nishihara
- Department of Veterinary Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan
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6
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Gibbs EM, Barthélémy F, Douine ED, Hardiman NC, Shieh PB, Khanlou N, Crosbie RH, Nelson SF, Miceli MC. Large in-frame 5' deletions in DMD associated with mild Duchenne muscular dystrophy: Two case reports and a review of the literature. Neuromuscul Disord 2019; 29:863-873. [PMID: 31672265 PMCID: PMC7092699 DOI: 10.1016/j.nmd.2019.09.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Revised: 08/28/2019] [Accepted: 09/10/2019] [Indexed: 10/26/2022]
Abstract
Duchenne muscular dystrophy is caused by mutations in the dystrophin-encoding DMD gene. While Duchenne is most commonly caused by large intragenic deletions that cause frameshift and complete loss of dystrophin expression, in-frame deletions in DMD can result in the expression of internally truncated dystrophin proteins and may be associated with a milder phenotype. In this study, we describe two individuals with large in-frame 5' deletions (exon 3-23 and exon 3-28) that remove the majority of the N-terminal region, including part of the actin binding and central rod domains. Both patients had progressive muscle weakness during childhood but are observed to have a relatively mild disease course compared to typical Duchenne. We show that in muscle biopsies from both patients, truncated dystrophin is expressed at the sarcolemma. We have additionally developed a patient-specific fibroblast-derived cell model, which can be inducibly reprogrammed to form myotubes that largely recapitulate biopsy findings for the patient with the exon 3-23 deletion, providing a culture model for future investigation of this unusual case. We discuss these mutations in the context of previously reported 5' in-frame DMD deletions and relevant animal models, and review the spectrum of phenotypes associated with these deletions.
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Affiliation(s)
- Elizabeth M Gibbs
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095, USA; Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, CA 90095, USA
| | - Florian Barthélémy
- Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, CA 90095, USA; Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Emilie D Douine
- Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, CA 90095, USA; Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Natalie C Hardiman
- Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, CA 90095, USA; Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Perry B Shieh
- Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, CA 90095, USA; Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, 90095, USA
| | - Negar Khanlou
- Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, CA 90095, USA; Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Rachelle H Crosbie
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095, USA; Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, CA 90095, USA; Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, 90095, USA; Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA
| | - Stanley F Nelson
- Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, CA 90095, USA; Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA; Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, 90095, USA
| | - M Carrie Miceli
- Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, CA 90095, USA; Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA; Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA.
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7
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Distinct mechanical properties in homologous spectrin-like repeats of utrophin. Sci Rep 2019; 9:5210. [PMID: 30914715 PMCID: PMC6435810 DOI: 10.1038/s41598-019-41569-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 03/12/2019] [Indexed: 11/09/2022] Open
Abstract
Patients with Duchenne muscular dystrophy (DMD) lack the protein dystrophin, which is a critical molecular component of the dystrophin-glycoprotein complex (DGC). Dystrophin is hypothesized to function as a molecular shock absorber that mechanically stabilizes the sarcolemma of striated muscle through interaction with the cortical actin cytoskeleton via its N-terminal half and with the transmembrane protein β-dystroglycan via its C-terminal region. Utrophin is a fetal homologue of dystrophin that can subserve many dystrophin functions and is therefore under active investigation as a dystrophin replacement therapy for DMD. Here, we report the first mechanical characterization of utrophin using atomic force microscopy (AFM). Our data indicate that the mechanical properties of spectrin-like repeats in utrophin are more in line with the PEVK and Ig-like repeats of titin rather than those reported for repeats in spectrin or dystrophin. Moreover, we measured markedly different unfolding characteristics for spectrin repeats within the N-terminal actin-binding half of utrophin compared to those in the C-terminal dystroglycan-binding half, even though they exhibit identical thermal denaturation profiles. Our results demonstrate dramatic differences in the mechanical properties of structurally homologous utrophin constructs and suggest that utrophin may function as a stiff elastic element in series with titin at the myotendinous junction.
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8
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McCourt JL, Talsness DM, Lindsay A, Arpke RW, Chatterton PD, Nelson DM, Chamberlain CM, Olthoff JT, Belanto JJ, McCourt PM, Kyba M, Lowe DA, Ervasti JM. Mouse models of two missense mutations in actin-binding domain 1 of dystrophin associated with Duchenne or Becker muscular dystrophy. Hum Mol Genet 2019; 27:451-462. [PMID: 29194514 DOI: 10.1093/hmg/ddx414] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2017] [Accepted: 11/17/2017] [Indexed: 01/03/2023] Open
Abstract
Missense mutations in the dystrophin protein can cause Duchenne muscular dystrophy (DMD) or Becker muscular dystrophy (BMD) through an undefined pathomechanism. In vitro studies suggest that missense mutations in the N-terminal actin-binding domain (ABD1) cause protein instability, and cultured myoblast studies reveal decreased expression levels that can be restored to wild-type with proteasome inhibitors. To further elucidate the pathophysiology of missense dystrophin in vivo, we generated two transgenic mdx mouse lines expressing L54R or L172H mutant dystrophin, which correspond to missense mutations identified in human patients with DMD or BMD, respectively. Our biochemical, histologic and physiologic analysis of the L54R and L172H mice show decreased levels of dystrophin which are proportional to the phenotypic severity. Proteasome inhibitors were ineffective in both the L54R and L172H mice, yet mice homozygous for the L172H transgene were able to express even higher levels of dystrophin which caused further improvements in muscle histology and physiology. Given that missense dystrophin is likely being degraded by the proteasome but whole body proteasome inhibition was not possible, we screened for ubiquitin-conjugating enzymes involved in targeting dystrophin to the proteasome. A myoblast cell line expressing L54R mutant dystrophin was screened with an siRNA library targeting E1, E2 and E3 ligases which identified Amn1, FBXO33, Zfand5 and Trim75. Our study establishes new mouse models of dystrophinopathy and identifies candidate E3 ligases that may specifically regulate dystrophin protein turnover in vivo.
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Affiliation(s)
| | - Dana M Talsness
- Department of Biochemistry, Molecular Biology and Biophysics
| | | | - Robert W Arpke
- Department of Pediatrics University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA
| | | | - D'anna M Nelson
- Department of Biochemistry, Molecular Biology and Biophysics
| | | | - John T Olthoff
- Department of Biochemistry, Molecular Biology and Biophysics
| | | | | | - Michael Kyba
- Department of Pediatrics University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA
| | - Dawn A Lowe
- Department of Physical Medicine and Rehabilitation
| | - James M Ervasti
- Department of Biochemistry, Molecular Biology and Biophysics
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9
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Belanto JJ, Olthoff JT, Mader TL, Chamberlain CM, Nelson DM, McCourt PM, Talsness DM, Gundersen GG, Lowe DA, Ervasti JM. Independent variability of microtubule perturbations associated with dystrophinopathy. Hum Mol Genet 2018; 25:4951-4961. [PMID: 28171583 DOI: 10.1093/hmg/ddw318] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Revised: 08/15/2016] [Accepted: 09/12/2016] [Indexed: 11/14/2022] Open
Abstract
Absence of the protein dystrophin causes Duchenne muscular dystrophy. Dystrophin directly binds to microtubules in vitro, and its absence in vivo correlates with disorganization of the subsarcolemmal microtubule lattice, increased detyrosination of α-tubulin, and altered redox signaling. We previously demonstrated that the dystrophin homologue utrophin neither binds microtubules in vitro nor rescues microtubule lattice organization when overexpressed in muscles of dystrophin-deficient mdx mice. Here, we fine-mapped the dystrophin domain necessary for microtubule binding to spectrin-like repeats 20–22. We show that transgenic mdx mice expressing a full-length dystrophin/utrophin chimera completely lacking microtubule binding activity are surprisingly rescued for all measured dystrophic phenotypes, including full restoration of microtubule lattice organization. Conversely, despite the presence of dystrophin at the sarcolemma, β-sarcoglycan-deficient skeletal muscle presents with a disorganized and densified microtubule lattice. Finally, we show that the levels of α-tubulin detyrosination remain significantly elevated to that of mdx levels in transgenic mdx mice expressing nearly full-length dystrophin. Our results demonstrate that the microtubule-associated perturbations of mdx muscle are distinct, separable, and can vary independently from other parameters previously ascribed to dystrophin deficiency.
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Affiliation(s)
- Joseph J Belanto
- Department of Biochemistry, Molecular Biology, and Biophysics, and Program in Molecular, Cellular, Developmental Biology, and Genetics, University of Minnesota - Twin Cities, Minneapolis, MN, USA
| | - John T Olthoff
- Department of Biochemistry, Molecular Biology, and Biophysics, and Program in Molecular, Cellular, Developmental Biology, and Genetics, University of Minnesota - Twin Cities, Minneapolis, MN, USA
| | - Tara L Mader
- Programs in Rehabilitation Science and Physical Therapy, Department of Physical Medicine and Rehabilitation, University of Minnesota - Twin Cities, Minneapolis, MN, USA
| | - Christopher M Chamberlain
- Department of Biochemistry, Molecular Biology, and Biophysics, and Program in Molecular, Cellular, Developmental Biology, and Genetics, University of Minnesota - Twin Cities, Minneapolis, MN, USA
| | - D'anna M Nelson
- Department of Biochemistry, Molecular Biology, and Biophysics, and Program in Molecular, Cellular, Developmental Biology, and Genetics, University of Minnesota - Twin Cities, Minneapolis, MN, USA
| | - Preston M McCourt
- Department of Biochemistry, Molecular Biology, and Biophysics, and Program in Molecular, Cellular, Developmental Biology, and Genetics, University of Minnesota - Twin Cities, Minneapolis, MN, USA
| | - Dana M Talsness
- Department of Biochemistry, Molecular Biology, and Biophysics, and Program in Molecular, Cellular, Developmental Biology, and Genetics, University of Minnesota - Twin Cities, Minneapolis, MN, USA
| | - Gregg G Gundersen
- Department of Pathology & Cell Biology, Columbia University, New York, NY, USA
| | - Dawn A Lowe
- Programs in Rehabilitation Science and Physical Therapy, Department of Physical Medicine and Rehabilitation, University of Minnesota - Twin Cities, Minneapolis, MN, USA
| | - James M Ervasti
- Department of Biochemistry, Molecular Biology, and Biophysics, and Program in Molecular, Cellular, Developmental Biology, and Genetics, University of Minnesota - Twin Cities, Minneapolis, MN, USA
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10
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Ako AE, Perroud PF, Innocent J, Demko V, Olsen OA, Johansen W. An intragenic mutagenesis strategy in Physcomitrella patens to preserve intron splicing. Sci Rep 2017; 7:5111. [PMID: 28698618 PMCID: PMC5505980 DOI: 10.1038/s41598-017-05309-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 05/26/2017] [Indexed: 12/27/2022] Open
Abstract
Gene targeting is a powerful reverse genetics technique for site-specific genome modification. Intrinsic homologous recombination in the moss Physcomitrella patens permits highly effective gene targeting, a characteristic that makes this organism a valuable model for functional genetics. Functional characterization of domains located within a multi-domain protein depends on the ability to generate mutants harboring genetic modifications at internal gene positions while maintaining the reading-frames of the flanking exons. In this study, we designed and evaluated different gene targeting constructs for targeted gene manipulation of sequences corresponding to internal domains of the DEFECTIVE KERNEL1 protein in Physcomitrella patens. Our results show that gene targeting-associated mutagenesis of introns can have adverse effects on splicing, corrupting the normal reading frame of the transcript. We show that successful genetic modification of internal sequences of multi-exon genes depends on gene-targeting strategies which insert the selection marker cassette into the 5' end of the intron and preserve the nucleotide sequence of the targeted intron.
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Affiliation(s)
- Ako Eugene Ako
- Inland Norway University of Applied Sciences, Holsetgata 31, N-2318, Hamar, Norway
| | - Pierre-François Perroud
- Philipps University Marburg, Plant Cell Biology II, Karl-von-Frisch-Str. 8, 35043, Marburg, Germany
| | - Joseph Innocent
- Inland Norway University of Applied Sciences, Holsetgata 31, N-2318, Hamar, Norway
| | - Viktor Demko
- Norwegian University of Life Sciences, P.O. Box 5003, N-1432, As, Norway
| | - Odd-Arne Olsen
- Norwegian University of Life Sciences, P.O. Box 5003, N-1432, As, Norway.
| | - Wenche Johansen
- Inland Norway University of Applied Sciences, Holsetgata 31, N-2318, Hamar, Norway.
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11
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Singh SM, Bandi S, Mallela KMG. The N-Terminal Flanking Region Modulates the Actin Binding Affinity of the Utrophin Tandem Calponin-Homology Domain. Biochemistry 2017; 56:2627-2636. [PMID: 28443334 DOI: 10.1021/acs.biochem.6b01117] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Despite sharing a high degree of sequence similarity, the tandem calponin-homology (CH) domain of utrophin binds to actin 30 times stronger than that of dystrophin. We have previously shown that this difference in actin binding affinity could not be ascribed to the differences in inter-CH-domain linkers [Bandi, S., et al. (2015) Biochemistry 54, 5480-5488]. Here, we examined the role of the N-terminal flanking region. The utrophin tandem CH domain contains a 27-residue flanking region before its CH1 domain. We examined its effect by comparing the structure and function of full-length utrophin tandem CH domain Utr(1-261) and its truncated Utr(28-261) construct. Both full-length and truncated constructs are monomers in solution, with no significant differences in their secondary or tertiary structures. Truncated construct Utr(28-261) binds to actin 30 times weaker than that of the full-length Utr(1-261), similar to that of the dystrophin tandem CH domain with a much shorter flanking region. Deletion of the N-terminal flanking region stabilizes the CH1 domain. The magnitude of the change in binding free energy upon truncation is similar to that of the change in thermodynamic stability. The isolated N-terminal peptide by itself is significantly random coil and does not bind to F-actin in the affinity range of Utr(1-261) and Utr(28-261). These results indicate that the N-terminal flanking region significantly affects the actin binding affinity of tandem CH domains. This observation further stresses that protein regions other than the three actin-binding surfaces identified earlier, irrespective of whether they directly bind to actin, also contribute to the actin binding affinity of tandem CH domains.
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Affiliation(s)
- Surinder M Singh
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, and ‡Program in Structural Biology and Biochemistry, University of Colorado Anschutz Medical Campus , 12850 East Montview Boulevard, MS C238, Aurora, Colorado 80045, United States
| | - Swati Bandi
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, and ‡Program in Structural Biology and Biochemistry, University of Colorado Anschutz Medical Campus , 12850 East Montview Boulevard, MS C238, Aurora, Colorado 80045, United States
| | - Krishna M G Mallela
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, and ‡Program in Structural Biology and Biochemistry, University of Colorado Anschutz Medical Campus , 12850 East Montview Boulevard, MS C238, Aurora, Colorado 80045, United States
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12
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Pini V, Morgan JE, Muntoni F, O’Neill HC. Genome Editing and Muscle Stem Cells as a Therapeutic Tool for Muscular Dystrophies. CURRENT STEM CELL REPORTS 2017; 3:137-148. [PMID: 28616376 PMCID: PMC5445179 DOI: 10.1007/s40778-017-0076-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Purpose of Review Muscular dystrophies are a group of severe degenerative disorders characterized by muscle fiber degeneration and death. Therapies designed to restore muscle homeostasis and to replace dying fibers are being experimented, but none of those in clinical trials are suitable to permanently address individual gene mutation. The purpose of this review is to discuss genome editing tools such as CRISPR/Cas (clustered regularly interspaced short palindromic repeats/CRISPR-associated), which enable direct sequence alteration and could potentially be adopted to correct the genetic defect leading to muscle impairment. Recent Findings Recent findings show that advances in gene therapy, when combined with traditional viral vector-based approaches, are bringing the field of regenerative medicine closer to precision-based medicine. Summary The use of such programmable nucleases is proving beneficial for the creation of more accurate in vitro and in vivo disease models. Several gene and cell-therapy studies have been performed on satellite cells, the primary skeletal muscle stem cells involved in muscle regeneration. However, these have mainly been based on artificial replacement or augmentation of the missing protein. Satellite cells are a particularly appealing target to address these innovative technologies for the treatment of muscular dystrophies.
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Affiliation(s)
- Veronica Pini
- Molecular and Developmental Neurosciences Program, The Dubowitz Neuromuscular Centre, UCL Great Ormond Street Institute of Child Health, 30 Guilford Street, London, WC1N 1EH UK
| | - Jennifer E. Morgan
- Molecular and Developmental Neurosciences Program, The Dubowitz Neuromuscular Centre, UCL Great Ormond Street Institute of Child Health, 30 Guilford Street, London, WC1N 1EH UK
| | - Francesco Muntoni
- Molecular and Developmental Neurosciences Program, The Dubowitz Neuromuscular Centre, UCL Great Ormond Street Institute of Child Health, 30 Guilford Street, London, WC1N 1EH UK
| | - Helen C. O’Neill
- Embryology, IVF and Reproductive Genetics Group, Institute for Women’s Health, University College London, 86-96 Chenies Mews, London, WC1E 6HX UK
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13
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Lentiviral vectors can be used for full-length dystrophin gene therapy. Sci Rep 2017; 7:44775. [PMID: 28303972 PMCID: PMC5356018 DOI: 10.1038/srep44775] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Accepted: 02/13/2017] [Indexed: 12/13/2022] Open
Abstract
Duchenne Muscular Dystrophy (DMD) is caused by a lack of dystrophin expression in patient muscle fibres. Current DMD gene therapy strategies rely on the expression of internally deleted forms of dystrophin, missing important functional domains. Viral gene transfer of full-length dystrophin could restore wild-type functionality, although this approach is restricted by the limited capacity of recombinant viral vectors. Lentiviral vectors can package larger transgenes than adeno-associated viruses, yet lentiviral vectors remain largely unexplored for full-length dystrophin delivery. In our work, we have demonstrated that lentiviral vectors can package and deliver inserts of a similar size to dystrophin. We report a novel approach for delivering large transgenes in lentiviruses, in which we demonstrate proof-of-concept for a ‘template-switching’ lentiviral vector that harnesses recombination events during reverse-transcription. During this work, we discovered that a standard, unmodified lentiviral vector was efficient in delivering full-length dystrophin to target cells, within a total genomic load of more than 15,000 base pairs. We have demonstrated gene therapy with this vector by restoring dystrophin expression in DMD myoblasts, where dystrophin was expressed at the sarcolemma of myotubes after myogenic differentiation. Ultimately, our work demonstrates proof-of-concept that lentiviruses can be used for permanent full-length dystrophin gene therapy, which presents a significant advancement in developing an effective treatment for DMD.
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14
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Counsell JR, Asgarian Z, Meng J, Ferrer V, Vink CA, Howe SJ, Waddington SN, Thrasher AJ, Muntoni F, Morgan JE, Danos O. Lentiviral vectors can be used for full-length dystrophin gene therapy. Sci Rep 2017; 7:79. [PMID: 28250438 PMCID: PMC5427806 DOI: 10.1038/s41598-017-00152-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Accepted: 02/13/2017] [Indexed: 01/08/2023] Open
Abstract
Duchenne Muscular Dystrophy (DMD) is caused by a lack of dystrophin expression in patient muscle fibres. Current DMD gene therapy strategies rely on the expression of internally deleted forms of dystrophin, missing important functional domains. Viral gene transfer of full-length dystrophin could restore wild-type functionality, although this approach is restricted by the limited capacity of recombinant viral vectors. Lentiviral vectors can package larger transgenes than adeno-associated viruses, yet lentiviral vectors remain largely unexplored for full-length dystrophin delivery. In our work, we have demonstrated that lentiviral vectors can package and deliver inserts of a similar size to dystrophin. We report a novel approach for delivering large transgenes in lentiviruses, in which we demonstrate proof-of-concept for a 'template-switching' lentiviral vector that harnesses recombination events during reverse-transcription. During this work, we discovered that a standard, unmodified lentiviral vector was efficient in delivering full-length dystrophin to target cells, within a total genomic load of more than 15,000 base pairs. We have demonstrated gene therapy with this vector by restoring dystrophin expression in DMD myoblasts, where dystrophin was expressed at the sarcolemma of myotubes after myogenic differentiation. Ultimately, our work demonstrates proof-of-concept that lentiviruses can be used for permanent full-length dystrophin gene therapy, which presents a significant advancement in developing an effective treatment for DMD.
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Affiliation(s)
- John R Counsell
- The Dubowitz Neuromuscular Centre, Molecular Neurosciences Section, Developmental Neurosciences Programme, UCL Great Ormond Street Institute of Child Health, 30 Guilford Street, London, WC1N 1EH, UK.
- UCL Cancer Institute, Paul O 'Gorman Building, University College London, 72 Huntley Street, London, WC1E 6BT, UK.
- Molecular and Cellular Immunology, Institute of Child Health, University College London, 30 Guilford Street, London, WC1N 1EH, UK.
- Gene Transfer Technology Group, Institute for Womens Health, University College London, 86-96, Chenies Mews, London, UK.
| | - Zeinab Asgarian
- The Dubowitz Neuromuscular Centre, Molecular Neurosciences Section, Developmental Neurosciences Programme, UCL Great Ormond Street Institute of Child Health, 30 Guilford Street, London, WC1N 1EH, UK
| | - Jinhong Meng
- The Dubowitz Neuromuscular Centre, Molecular Neurosciences Section, Developmental Neurosciences Programme, UCL Great Ormond Street Institute of Child Health, 30 Guilford Street, London, WC1N 1EH, UK
| | - Veronica Ferrer
- UCL Cancer Institute, Paul O 'Gorman Building, University College London, 72 Huntley Street, London, WC1E 6BT, UK
| | - Conrad A Vink
- Molecular and Cellular Immunology, Institute of Child Health, University College London, 30 Guilford Street, London, WC1N 1EH, UK
| | - Steven J Howe
- Molecular and Cellular Immunology, Institute of Child Health, University College London, 30 Guilford Street, London, WC1N 1EH, UK
| | - Simon N Waddington
- Gene Transfer Technology Group, Institute for Womens Health, University College London, 86-96, Chenies Mews, London, UK
- MRC Antiviral Gene Therapy Research Unit, Faculty of Health Sciences, University of the Witswatersrand, Johannesburg, South Africa
| | - Adrian J Thrasher
- Molecular and Cellular Immunology, Institute of Child Health, University College London, 30 Guilford Street, London, WC1N 1EH, UK
| | - Francesco Muntoni
- The Dubowitz Neuromuscular Centre, Molecular Neurosciences Section, Developmental Neurosciences Programme, UCL Great Ormond Street Institute of Child Health, 30 Guilford Street, London, WC1N 1EH, UK
| | - Jennifer E Morgan
- The Dubowitz Neuromuscular Centre, Molecular Neurosciences Section, Developmental Neurosciences Programme, UCL Great Ormond Street Institute of Child Health, 30 Guilford Street, London, WC1N 1EH, UK
| | - Olivier Danos
- UCL Cancer Institute, Paul O 'Gorman Building, University College London, 72 Huntley Street, London, WC1E 6BT, UK
- Biogen, 14 Cambridge Center, Cambridge, MA, 02142, USA
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15
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Singh SM, Bandi S, Mallela KMG. The N- and C-Terminal Domains Differentially Contribute to the Structure and Function of Dystrophin and Utrophin Tandem Calponin-Homology Domains. Biochemistry 2015; 54:6942-50. [PMID: 26516677 DOI: 10.1021/acs.biochem.5b00969] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Dystrophin and utrophin are two muscle proteins involved in Duchenne/Becker muscular dystrophy. Both proteins use tandem calponin-homology (CH) domains to bind to F-actin. We probed the role of N-terminal CH1 and C-terminal CH2 domains in the structure and function of dystrophin tandem CH domain and compared with our earlier results on utrophin to understand the unifying principles of how tandem CH domains work. Actin cosedimentation assays indicate that the isolated CH2 domain of dystrophin weakly binds to F-actin compared to the full-length tandem CH domain. In contrast, the isolated CH1 domain binds to F-actin with an affinity similar to that of the full-length tandem CH domain. Thus, the obvious question is why the dystrophin tandem CH domain requires CH2, when its actin binding is determined primarily by CH1. To answer, we probed the structural stabilities of CH domains. The isolated CH1 domain is very unstable and is prone to serious aggregation. The isolated CH2 domain is very stable, similar to the full-length tandem CH domain. These results indicate that the main role of CH2 is to stabilize the tandem CH domain structure. These conclusions from dystrophin agree with our earlier results on utrophin, indicating that this phenomenon of differential contribution of CH domains to the structure and function of tandem CH domains may be quite general. The N-terminal CH1 domains primarily determine the actin binding function whereas the C-terminal CH2 domains primarily determine the structural stability of tandem CH domains, and the extent of stabilization depends on the strength of inter-CH domain interactions.
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Affiliation(s)
- Surinder M Singh
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, and ‡Program in Structural Biology and Biochemistry, University of Colorado Anschutz Medical Campus , Aurora, Colorado 80045, United States
| | - Swati Bandi
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, and ‡Program in Structural Biology and Biochemistry, University of Colorado Anschutz Medical Campus , Aurora, Colorado 80045, United States
| | - Krishna M G Mallela
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, and ‡Program in Structural Biology and Biochemistry, University of Colorado Anschutz Medical Campus , Aurora, Colorado 80045, United States
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16
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Talsness DM, Belanto JJ, Ervasti JM. Disease-proportional proteasomal degradation of missense dystrophins. Proc Natl Acad Sci U S A 2015; 112:12414-9. [PMID: 26392559 PMCID: PMC4603481 DOI: 10.1073/pnas.1508755112] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The 427-kDa protein dystrophin is expressed in striated muscle where it physically links the interior of muscle fibers to the extracellular matrix. A range of mutations in the DMD gene encoding dystrophin lead to a severe muscular dystrophy known as Duchenne (DMD) or a typically milder form known as Becker (BMD). Patients with nonsense mutations in dystrophin are specifically targeted by stop codon read-through drugs, whereas out-of-frame deletions and insertions are targeted by exon-skipping therapies. Both treatment strategies are currently in clinical trials. Dystrophin missense mutations, however, cause a wide range of phenotypic severity in patients. The molecular and cellular consequences of such mutations are not well understood, and there are no therapies specifically targeting this genotype. Here, we have modeled two representative missense mutations, L54R and L172H, causing DMD and BMD, respectively, in full-length dystrophin. In vitro, the mutation associated with the mild phenotype (L172H) caused a minor decrease in tertiary stability, whereas the L54R mutation associated with a severe phenotype had a more dramatic effect. When stably expressed in mammalian muscle cells, the mutations caused steady-state decreases in dystrophin protein levels inversely proportional to the tertiary stability and directly caused by proteasomal degradation. Both proteasome inhibitors and heat shock activators were able to increase mutant dystrophin to WT levels, establishing the new cell lines as a platform to screen for potential therapeutics personalized to patients with destabilized dystrophin.
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Affiliation(s)
- Dana M Talsness
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota-Twin Cities, Minneapolis, MN 55455
| | - Joseph J Belanto
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota-Twin Cities, Minneapolis, MN 55455
| | - James M Ervasti
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota-Twin Cities, Minneapolis, MN 55455
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17
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Bandi S, Singh SM, Mallela KMG. Interdomain Linker Determines Primarily the Structural Stability of Dystrophin and Utrophin Tandem Calponin-Homology Domains Rather than Their Actin-Binding Affinity. Biochemistry 2015; 54:5480-8. [PMID: 26288220 DOI: 10.1021/acs.biochem.5b00741] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Tandem calponin-homology (CH) domains are the most common actin-binding domains in proteins. However, structural principles underlying their function are poorly understood. These tandem domains exist in multiple conformations with varying degrees of inter-CH-domain interactions. Dystrophin and utrophin tandem CH domains share high sequence similarity (∼82%), yet differ in their structural stability and actin-binding affinity. We examined whether the conformational differences between the two tandem CH domains can explain differences in their stability and actin binding. Dystrophin tandem CH domain is more stable by ∼4 kcal/mol than that of utrophin. Individual CH domains of dystrophin and utrophin have identical structures but differ in their relative orientation around the interdomain linker. We swapped the linkers between dystrophin and utrophin tandem CH domains. Dystrophin tandem CH domain with utrophin linker (DUL) has similar stability as that of utrophin tandem CH domain. Utrophin tandem CH domain with dystrophin linker (UDL) has similar stability as that of dystrophin tandem CH domain. Dystrophin tandem CH domain binds to F-actin ∼30 times weaker than that of utrophin. After linker swapping, DUL has twice the binding affinity as that of dystrophin tandem CH domain. Similarly, UDL has half the binding affinity as that of utrophin tandem CH domain. However, changes in binding free energies due to linker swapping are much lower by an order of magnitude compared to the corresponding changes in unfolding free energies. These results indicate that the linker region determines primarily the structural stability of tandem CH domains rather than their actin-binding affinity.
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Affiliation(s)
- Swati Bandi
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, and ‡Program in Structural Biology and Biochemistry, University of Colorado Anschutz Medical Campus , Aurora, Colorado 80045, United States
| | - Surinder M Singh
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, and ‡Program in Structural Biology and Biochemistry, University of Colorado Anschutz Medical Campus , Aurora, Colorado 80045, United States
| | - Krishna M G Mallela
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, and ‡Program in Structural Biology and Biochemistry, University of Colorado Anschutz Medical Campus , Aurora, Colorado 80045, United States
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18
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McCourt JL, Rhett KK, Jaeger MA, Belanto JJ, Talsness DM, Ervasti JM. In vitro stability of therapeutically relevant, internally truncated dystrophins. Skelet Muscle 2015; 5:13. [PMID: 25954502 PMCID: PMC4424174 DOI: 10.1186/s13395-015-0040-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2015] [Accepted: 04/14/2015] [Indexed: 12/21/2022] Open
Abstract
Background The X-linked recessive disease Duchenne muscular dystrophy (DMD) is caused by mutations in the gene encoding the protein dystrophin. Despite its large size, dystrophin is a highly stable protein, demonstrating cooperative unfolding during thermal denaturation as monitored by circular dichroism spectroscopy. In contrast, internal sequence deletions have been associated with a loss of the cooperative unfolding and cause in vitro protein aggregation. Several emerging therapy options for DMD utilize internally deleted micro-dystrophins and multi-exon-skipped dystrophins that produce partially functional proteins, but the stability of such internally truncated proteins has not been investigated. Methods In this study, we analyzed the in vitro stability of human dystrophin constructs skipped around exon 45 or exon 51, several dystrophin gene therapy constructs, as well as human full-length and micro-utrophin. Constructs were expressed in insect cells using the baculovirus system, purified by affinity chromatography, and analyzed by high-speed sedimentation, circular dichroism spectroscopy, and differential scanning fluorimetry. Results Our results reveal that not all gene therapy constructs display stabilities consistent with full-length human dystrophin. However, all dystrophins skipped in-frame around exon 45 or exon 51 show stability profiles congruent with intact human dystrophin. Similar to previous studies of mouse proteins, full-length human utrophin also displays stability similar to human dystrophin and does not appear to be affected by a large internal deletion. Conclusions Our results suggest that the in vitro stability of human dystrophin is less sensitive to smaller deletions at natural exon boundaries than larger, more complex deletions present in some gene therapy constructs.
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Affiliation(s)
- Jackie L McCourt
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota - Twin Cities, Minneapolis, MN 55455 USA
| | - Katrina K Rhett
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota - Twin Cities, Minneapolis, MN 55455 USA
| | - Michele A Jaeger
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota - Twin Cities, Minneapolis, MN 55455 USA
| | - Joseph J Belanto
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota - Twin Cities, Minneapolis, MN 55455 USA
| | - Dana M Talsness
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota - Twin Cities, Minneapolis, MN 55455 USA
| | - James M Ervasti
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota - Twin Cities, Minneapolis, MN 55455 USA
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19
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Anthony K, Arechavala-Gomeza V, Taylor LE, Vulin A, Kaminoh Y, Torelli S, Feng L, Janghra N, Bonne G, Beuvin M, Barresi R, Henderson M, Laval S, Lourbakos A, Campion G, Straub V, Voit T, Sewry CA, Morgan JE, Flanigan KM, Muntoni F. Dystrophin quantification: Biological and translational research implications. Neurology 2014; 83:2062-9. [PMID: 25355828 PMCID: PMC4248450 DOI: 10.1212/wnl.0000000000001025] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Accepted: 09/02/2014] [Indexed: 01/16/2023] Open
Abstract
OBJECTIVE We formed a multi-institution collaboration in order to compare dystrophin quantification methods, reach a consensus on the most reliable method, and report its biological significance in the context of clinical trials. METHODS Five laboratories with expertise in dystrophin quantification performed a data-driven comparative analysis of a single reference set of normal and dystrophinopathy muscle biopsies using quantitative immunohistochemistry and Western blotting. We developed standardized protocols and assessed inter- and intralaboratory variability over a wide range of dystrophin expression levels. RESULTS Results from the different laboratories were highly concordant with minimal inter- and intralaboratory variability, particularly with quantitative immunohistochemistry. There was a good level of agreement between data generated by immunohistochemistry and Western blotting, although immunohistochemistry was more sensitive. Furthermore, mean dystrophin levels determined by alternative quantitative immunohistochemistry methods were highly comparable. CONCLUSIONS Considering the biological function of dystrophin at the sarcolemma, our data indicate that the combined use of quantitative immunohistochemistry and Western blotting are reliable biochemical outcome measures for Duchenne muscular dystrophy clinical trials, and that standardized protocols can be comparable between competent laboratories. The methodology validated in our study will facilitate the development of experimental therapies focused on dystrophin production and their regulatory approval.
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Affiliation(s)
- Karen Anthony
- From The Dubowitz Neuromuscular Centre (K.A., V.A.-G., S.T., L.F., N.J., C.A.S., J.E.M., F.M.), UCL, Institute of Child Health, London, UK; The Center for Gene Therapy (L.E.T., A.V., Y.K., K.M.F.), The Research Institute at Nationwide Children's Hospital, Columbus, OH; Institut de Myologie (G.B., M.B., T.V.), UPMC UM76, INSERM U 794, CNRS UMR 7215, Paris, France; Institute of Genetic Medicine (R.B., M.H., S.L., V.S.), Newcastle University, UK; and Prosensa Therapeutics (A.L., G.C.), Leiden, the Netherlands. V.A.-G. is currently affiliated with the Neuromuscular Disorders Group, BioCruces Health Research Institute, Barakaldo, Spain
| | - Virginia Arechavala-Gomeza
- From The Dubowitz Neuromuscular Centre (K.A., V.A.-G., S.T., L.F., N.J., C.A.S., J.E.M., F.M.), UCL, Institute of Child Health, London, UK; The Center for Gene Therapy (L.E.T., A.V., Y.K., K.M.F.), The Research Institute at Nationwide Children's Hospital, Columbus, OH; Institut de Myologie (G.B., M.B., T.V.), UPMC UM76, INSERM U 794, CNRS UMR 7215, Paris, France; Institute of Genetic Medicine (R.B., M.H., S.L., V.S.), Newcastle University, UK; and Prosensa Therapeutics (A.L., G.C.), Leiden, the Netherlands. V.A.-G. is currently affiliated with the Neuromuscular Disorders Group, BioCruces Health Research Institute, Barakaldo, Spain
| | - Laura E Taylor
- From The Dubowitz Neuromuscular Centre (K.A., V.A.-G., S.T., L.F., N.J., C.A.S., J.E.M., F.M.), UCL, Institute of Child Health, London, UK; The Center for Gene Therapy (L.E.T., A.V., Y.K., K.M.F.), The Research Institute at Nationwide Children's Hospital, Columbus, OH; Institut de Myologie (G.B., M.B., T.V.), UPMC UM76, INSERM U 794, CNRS UMR 7215, Paris, France; Institute of Genetic Medicine (R.B., M.H., S.L., V.S.), Newcastle University, UK; and Prosensa Therapeutics (A.L., G.C.), Leiden, the Netherlands. V.A.-G. is currently affiliated with the Neuromuscular Disorders Group, BioCruces Health Research Institute, Barakaldo, Spain
| | - Adeline Vulin
- From The Dubowitz Neuromuscular Centre (K.A., V.A.-G., S.T., L.F., N.J., C.A.S., J.E.M., F.M.), UCL, Institute of Child Health, London, UK; The Center for Gene Therapy (L.E.T., A.V., Y.K., K.M.F.), The Research Institute at Nationwide Children's Hospital, Columbus, OH; Institut de Myologie (G.B., M.B., T.V.), UPMC UM76, INSERM U 794, CNRS UMR 7215, Paris, France; Institute of Genetic Medicine (R.B., M.H., S.L., V.S.), Newcastle University, UK; and Prosensa Therapeutics (A.L., G.C.), Leiden, the Netherlands. V.A.-G. is currently affiliated with the Neuromuscular Disorders Group, BioCruces Health Research Institute, Barakaldo, Spain
| | - Yuuki Kaminoh
- From The Dubowitz Neuromuscular Centre (K.A., V.A.-G., S.T., L.F., N.J., C.A.S., J.E.M., F.M.), UCL, Institute of Child Health, London, UK; The Center for Gene Therapy (L.E.T., A.V., Y.K., K.M.F.), The Research Institute at Nationwide Children's Hospital, Columbus, OH; Institut de Myologie (G.B., M.B., T.V.), UPMC UM76, INSERM U 794, CNRS UMR 7215, Paris, France; Institute of Genetic Medicine (R.B., M.H., S.L., V.S.), Newcastle University, UK; and Prosensa Therapeutics (A.L., G.C.), Leiden, the Netherlands. V.A.-G. is currently affiliated with the Neuromuscular Disorders Group, BioCruces Health Research Institute, Barakaldo, Spain
| | - Silvia Torelli
- From The Dubowitz Neuromuscular Centre (K.A., V.A.-G., S.T., L.F., N.J., C.A.S., J.E.M., F.M.), UCL, Institute of Child Health, London, UK; The Center for Gene Therapy (L.E.T., A.V., Y.K., K.M.F.), The Research Institute at Nationwide Children's Hospital, Columbus, OH; Institut de Myologie (G.B., M.B., T.V.), UPMC UM76, INSERM U 794, CNRS UMR 7215, Paris, France; Institute of Genetic Medicine (R.B., M.H., S.L., V.S.), Newcastle University, UK; and Prosensa Therapeutics (A.L., G.C.), Leiden, the Netherlands. V.A.-G. is currently affiliated with the Neuromuscular Disorders Group, BioCruces Health Research Institute, Barakaldo, Spain
| | - Lucy Feng
- From The Dubowitz Neuromuscular Centre (K.A., V.A.-G., S.T., L.F., N.J., C.A.S., J.E.M., F.M.), UCL, Institute of Child Health, London, UK; The Center for Gene Therapy (L.E.T., A.V., Y.K., K.M.F.), The Research Institute at Nationwide Children's Hospital, Columbus, OH; Institut de Myologie (G.B., M.B., T.V.), UPMC UM76, INSERM U 794, CNRS UMR 7215, Paris, France; Institute of Genetic Medicine (R.B., M.H., S.L., V.S.), Newcastle University, UK; and Prosensa Therapeutics (A.L., G.C.), Leiden, the Netherlands. V.A.-G. is currently affiliated with the Neuromuscular Disorders Group, BioCruces Health Research Institute, Barakaldo, Spain
| | - Narinder Janghra
- From The Dubowitz Neuromuscular Centre (K.A., V.A.-G., S.T., L.F., N.J., C.A.S., J.E.M., F.M.), UCL, Institute of Child Health, London, UK; The Center for Gene Therapy (L.E.T., A.V., Y.K., K.M.F.), The Research Institute at Nationwide Children's Hospital, Columbus, OH; Institut de Myologie (G.B., M.B., T.V.), UPMC UM76, INSERM U 794, CNRS UMR 7215, Paris, France; Institute of Genetic Medicine (R.B., M.H., S.L., V.S.), Newcastle University, UK; and Prosensa Therapeutics (A.L., G.C.), Leiden, the Netherlands. V.A.-G. is currently affiliated with the Neuromuscular Disorders Group, BioCruces Health Research Institute, Barakaldo, Spain
| | - Gisèle Bonne
- From The Dubowitz Neuromuscular Centre (K.A., V.A.-G., S.T., L.F., N.J., C.A.S., J.E.M., F.M.), UCL, Institute of Child Health, London, UK; The Center for Gene Therapy (L.E.T., A.V., Y.K., K.M.F.), The Research Institute at Nationwide Children's Hospital, Columbus, OH; Institut de Myologie (G.B., M.B., T.V.), UPMC UM76, INSERM U 794, CNRS UMR 7215, Paris, France; Institute of Genetic Medicine (R.B., M.H., S.L., V.S.), Newcastle University, UK; and Prosensa Therapeutics (A.L., G.C.), Leiden, the Netherlands. V.A.-G. is currently affiliated with the Neuromuscular Disorders Group, BioCruces Health Research Institute, Barakaldo, Spain
| | - Maud Beuvin
- From The Dubowitz Neuromuscular Centre (K.A., V.A.-G., S.T., L.F., N.J., C.A.S., J.E.M., F.M.), UCL, Institute of Child Health, London, UK; The Center for Gene Therapy (L.E.T., A.V., Y.K., K.M.F.), The Research Institute at Nationwide Children's Hospital, Columbus, OH; Institut de Myologie (G.B., M.B., T.V.), UPMC UM76, INSERM U 794, CNRS UMR 7215, Paris, France; Institute of Genetic Medicine (R.B., M.H., S.L., V.S.), Newcastle University, UK; and Prosensa Therapeutics (A.L., G.C.), Leiden, the Netherlands. V.A.-G. is currently affiliated with the Neuromuscular Disorders Group, BioCruces Health Research Institute, Barakaldo, Spain
| | - Rita Barresi
- From The Dubowitz Neuromuscular Centre (K.A., V.A.-G., S.T., L.F., N.J., C.A.S., J.E.M., F.M.), UCL, Institute of Child Health, London, UK; The Center for Gene Therapy (L.E.T., A.V., Y.K., K.M.F.), The Research Institute at Nationwide Children's Hospital, Columbus, OH; Institut de Myologie (G.B., M.B., T.V.), UPMC UM76, INSERM U 794, CNRS UMR 7215, Paris, France; Institute of Genetic Medicine (R.B., M.H., S.L., V.S.), Newcastle University, UK; and Prosensa Therapeutics (A.L., G.C.), Leiden, the Netherlands. V.A.-G. is currently affiliated with the Neuromuscular Disorders Group, BioCruces Health Research Institute, Barakaldo, Spain
| | - Matt Henderson
- From The Dubowitz Neuromuscular Centre (K.A., V.A.-G., S.T., L.F., N.J., C.A.S., J.E.M., F.M.), UCL, Institute of Child Health, London, UK; The Center for Gene Therapy (L.E.T., A.V., Y.K., K.M.F.), The Research Institute at Nationwide Children's Hospital, Columbus, OH; Institut de Myologie (G.B., M.B., T.V.), UPMC UM76, INSERM U 794, CNRS UMR 7215, Paris, France; Institute of Genetic Medicine (R.B., M.H., S.L., V.S.), Newcastle University, UK; and Prosensa Therapeutics (A.L., G.C.), Leiden, the Netherlands. V.A.-G. is currently affiliated with the Neuromuscular Disorders Group, BioCruces Health Research Institute, Barakaldo, Spain
| | - Steven Laval
- From The Dubowitz Neuromuscular Centre (K.A., V.A.-G., S.T., L.F., N.J., C.A.S., J.E.M., F.M.), UCL, Institute of Child Health, London, UK; The Center for Gene Therapy (L.E.T., A.V., Y.K., K.M.F.), The Research Institute at Nationwide Children's Hospital, Columbus, OH; Institut de Myologie (G.B., M.B., T.V.), UPMC UM76, INSERM U 794, CNRS UMR 7215, Paris, France; Institute of Genetic Medicine (R.B., M.H., S.L., V.S.), Newcastle University, UK; and Prosensa Therapeutics (A.L., G.C.), Leiden, the Netherlands. V.A.-G. is currently affiliated with the Neuromuscular Disorders Group, BioCruces Health Research Institute, Barakaldo, Spain
| | - Afrodite Lourbakos
- From The Dubowitz Neuromuscular Centre (K.A., V.A.-G., S.T., L.F., N.J., C.A.S., J.E.M., F.M.), UCL, Institute of Child Health, London, UK; The Center for Gene Therapy (L.E.T., A.V., Y.K., K.M.F.), The Research Institute at Nationwide Children's Hospital, Columbus, OH; Institut de Myologie (G.B., M.B., T.V.), UPMC UM76, INSERM U 794, CNRS UMR 7215, Paris, France; Institute of Genetic Medicine (R.B., M.H., S.L., V.S.), Newcastle University, UK; and Prosensa Therapeutics (A.L., G.C.), Leiden, the Netherlands. V.A.-G. is currently affiliated with the Neuromuscular Disorders Group, BioCruces Health Research Institute, Barakaldo, Spain
| | - Giles Campion
- From The Dubowitz Neuromuscular Centre (K.A., V.A.-G., S.T., L.F., N.J., C.A.S., J.E.M., F.M.), UCL, Institute of Child Health, London, UK; The Center for Gene Therapy (L.E.T., A.V., Y.K., K.M.F.), The Research Institute at Nationwide Children's Hospital, Columbus, OH; Institut de Myologie (G.B., M.B., T.V.), UPMC UM76, INSERM U 794, CNRS UMR 7215, Paris, France; Institute of Genetic Medicine (R.B., M.H., S.L., V.S.), Newcastle University, UK; and Prosensa Therapeutics (A.L., G.C.), Leiden, the Netherlands. V.A.-G. is currently affiliated with the Neuromuscular Disorders Group, BioCruces Health Research Institute, Barakaldo, Spain
| | - Volker Straub
- From The Dubowitz Neuromuscular Centre (K.A., V.A.-G., S.T., L.F., N.J., C.A.S., J.E.M., F.M.), UCL, Institute of Child Health, London, UK; The Center for Gene Therapy (L.E.T., A.V., Y.K., K.M.F.), The Research Institute at Nationwide Children's Hospital, Columbus, OH; Institut de Myologie (G.B., M.B., T.V.), UPMC UM76, INSERM U 794, CNRS UMR 7215, Paris, France; Institute of Genetic Medicine (R.B., M.H., S.L., V.S.), Newcastle University, UK; and Prosensa Therapeutics (A.L., G.C.), Leiden, the Netherlands. V.A.-G. is currently affiliated with the Neuromuscular Disorders Group, BioCruces Health Research Institute, Barakaldo, Spain
| | - Thomas Voit
- From The Dubowitz Neuromuscular Centre (K.A., V.A.-G., S.T., L.F., N.J., C.A.S., J.E.M., F.M.), UCL, Institute of Child Health, London, UK; The Center for Gene Therapy (L.E.T., A.V., Y.K., K.M.F.), The Research Institute at Nationwide Children's Hospital, Columbus, OH; Institut de Myologie (G.B., M.B., T.V.), UPMC UM76, INSERM U 794, CNRS UMR 7215, Paris, France; Institute of Genetic Medicine (R.B., M.H., S.L., V.S.), Newcastle University, UK; and Prosensa Therapeutics (A.L., G.C.), Leiden, the Netherlands. V.A.-G. is currently affiliated with the Neuromuscular Disorders Group, BioCruces Health Research Institute, Barakaldo, Spain
| | - Caroline A Sewry
- From The Dubowitz Neuromuscular Centre (K.A., V.A.-G., S.T., L.F., N.J., C.A.S., J.E.M., F.M.), UCL, Institute of Child Health, London, UK; The Center for Gene Therapy (L.E.T., A.V., Y.K., K.M.F.), The Research Institute at Nationwide Children's Hospital, Columbus, OH; Institut de Myologie (G.B., M.B., T.V.), UPMC UM76, INSERM U 794, CNRS UMR 7215, Paris, France; Institute of Genetic Medicine (R.B., M.H., S.L., V.S.), Newcastle University, UK; and Prosensa Therapeutics (A.L., G.C.), Leiden, the Netherlands. V.A.-G. is currently affiliated with the Neuromuscular Disorders Group, BioCruces Health Research Institute, Barakaldo, Spain
| | - Jennifer E Morgan
- From The Dubowitz Neuromuscular Centre (K.A., V.A.-G., S.T., L.F., N.J., C.A.S., J.E.M., F.M.), UCL, Institute of Child Health, London, UK; The Center for Gene Therapy (L.E.T., A.V., Y.K., K.M.F.), The Research Institute at Nationwide Children's Hospital, Columbus, OH; Institut de Myologie (G.B., M.B., T.V.), UPMC UM76, INSERM U 794, CNRS UMR 7215, Paris, France; Institute of Genetic Medicine (R.B., M.H., S.L., V.S.), Newcastle University, UK; and Prosensa Therapeutics (A.L., G.C.), Leiden, the Netherlands. V.A.-G. is currently affiliated with the Neuromuscular Disorders Group, BioCruces Health Research Institute, Barakaldo, Spain
| | - Kevin M Flanigan
- From The Dubowitz Neuromuscular Centre (K.A., V.A.-G., S.T., L.F., N.J., C.A.S., J.E.M., F.M.), UCL, Institute of Child Health, London, UK; The Center for Gene Therapy (L.E.T., A.V., Y.K., K.M.F.), The Research Institute at Nationwide Children's Hospital, Columbus, OH; Institut de Myologie (G.B., M.B., T.V.), UPMC UM76, INSERM U 794, CNRS UMR 7215, Paris, France; Institute of Genetic Medicine (R.B., M.H., S.L., V.S.), Newcastle University, UK; and Prosensa Therapeutics (A.L., G.C.), Leiden, the Netherlands. V.A.-G. is currently affiliated with the Neuromuscular Disorders Group, BioCruces Health Research Institute, Barakaldo, Spain
| | - Francesco Muntoni
- From The Dubowitz Neuromuscular Centre (K.A., V.A.-G., S.T., L.F., N.J., C.A.S., J.E.M., F.M.), UCL, Institute of Child Health, London, UK; The Center for Gene Therapy (L.E.T., A.V., Y.K., K.M.F.), The Research Institute at Nationwide Children's Hospital, Columbus, OH; Institut de Myologie (G.B., M.B., T.V.), UPMC UM76, INSERM U 794, CNRS UMR 7215, Paris, France; Institute of Genetic Medicine (R.B., M.H., S.L., V.S.), Newcastle University, UK; and Prosensa Therapeutics (A.L., G.C.), Leiden, the Netherlands. V.A.-G. is currently affiliated with the Neuromuscular Disorders Group, BioCruces Health Research Institute, Barakaldo, Spain.
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Nicolas A, Raguénès-Nicol C, Ben Yaou R, Ameziane-Le Hir S, Chéron A, Vié V, Claustres M, Leturcq F, Delalande O, Hubert JF, Tuffery-Giraud S, Giudice E, Le Rumeur E. Becker muscular dystrophy severity is linked to the structure of dystrophin. Hum Mol Genet 2014; 24:1267-79. [DOI: 10.1093/hmg/ddu537] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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Singh SM, Bandi S, Shah DD, Armstrong G, Mallela KMG. Missense mutation Lys18Asn in dystrophin that triggers X-linked dilated cardiomyopathy decreases protein stability, increases protein unfolding, and perturbs protein structure, but does not affect protein function. PLoS One 2014; 9:e110439. [PMID: 25340340 PMCID: PMC4207752 DOI: 10.1371/journal.pone.0110439] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 09/15/2014] [Indexed: 11/19/2022] Open
Abstract
Genetic mutations in a vital muscle protein dystrophin trigger X-linked dilated cardiomyopathy (XLDCM). However, disease mechanisms at the fundamental protein level are not understood. Such molecular knowledge is essential for developing therapies for XLDCM. Our main objective is to understand the effect of disease-causing mutations on the structure and function of dystrophin. This study is on a missense mutation K18N. The K18N mutation occurs in the N-terminal actin binding domain (N-ABD). We created and expressed the wild-type (WT) N-ABD and its K18N mutant, and purified to homogeneity. Reversible folding experiments demonstrated that both mutant and WT did not aggregate upon refolding. Mutation did not affect the protein's overall secondary structure, as indicated by no changes in circular dichroism of the protein. However, the mutant is thermodynamically less stable than the WT (denaturant melts), and unfolds faster than the WT (stopped-flow kinetics). Despite having global secondary structure similar to that of the WT, mutant showed significant local structural changes at many amino acids when compared with the WT (heteronuclear NMR experiments). These structural changes indicate that the effect of mutation is propagated over long distances in the protein structure. Contrary to these structural and stability changes, the mutant had no significant effect on the actin-binding function as evident from co-sedimentation and depolymerization assays. These results summarize that the K18N mutation decreases thermodynamic stability, accelerates unfolding, perturbs protein structure, but does not affect the function. Therefore, K18N is a stability defect rather than a functional defect. Decrease in stability and increase in unfolding decrease the net population of dystrophin molecules available for function, which might trigger XLDCM. Consistently, XLDCM patients have decreased levels of dystrophin in cardiac muscle.
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Affiliation(s)
- Surinder M. Singh
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Swati Bandi
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Dinen D. Shah
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Geoffrey Armstrong
- Department of Chemistry and Biochemistry, University of Colorado Boulder, Boulder, Colorado, United States of America
| | - Krishna M. G. Mallela
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
- Program in Structural Biology and Biochemistry, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
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Uwineza A, Hitayezu J, Murorunkwere S, Ndinkabandi J, Kalala Malu CK, Caberg JH, Dideberg V, Bours V, Mutesa L. Genetic diagnosis of Duchenne and Becker muscular dystrophy using multiplex ligation-dependent probe amplification in Rwandan patients. J Trop Pediatr 2014; 60:112-7. [PMID: 24213305 DOI: 10.1093/tropej/fmt090] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Duchenne and Becker muscular dystrophies are the most common clinical forms of muscular dystrophies. They are genetically X-linked diseases caused by a mutation in the dystrophin (DMD) gene. A genetic diagnosis was carried out in six Rwandan patients presenting a phenotype of Duchenne and Becker muscular dystrophies and six asymptomatic female carrier relatives using multiplex ligation-dependent probe amplification (MLPA). Our results revealed deletion of the exons 48-51 in one patient, an inherited deletion of the exons 8-21 in two brothers and a de novo deletion of the exons 46-50 in the fourth patient. No copy number variation was found in two patients. Only one female carrier presented exon deletion in the DMD gene. This is the first cohort of genetic analysis in Rwandan patients affected by Duchenne and Becker muscular dystrophies. This report confirmed that MLPA assay can be easily implemented in low-income countries.
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Affiliation(s)
- Annette Uwineza
- Center for Medical Genetics, Department of Molecular Biology & Cytogenetics, Faculty of Medicine, National University of Rwanda, PO Box 30-Butare, Rwanda
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The N-terminal actin-binding tandem calponin-homology (CH) domain of dystrophin is in a closed conformation in solution and when bound to F-actin. Biophys J 2013. [PMID: 23199925 DOI: 10.1016/j.bpj.2012.08.066] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Deficiency of the vital muscle protein dystrophin triggers Duchenne/Becker muscular dystrophy, but the structure-function relationship of dystrophin is poorly understood. To date, molecular structures of three dystrophin domains have been determined, of which the N-terminal actin-binding domain (N-ABD or ABD1) is of particular interest. This domain is composed of two calponin-homology (CH) domains, which form an important class of ABDs in muscle proteins. A previously determined x-ray structure indicates that the dystrophin N-ABD is a domain-swapped dimer, with each monomer adopting an extended, open conformation in which the two CH domains do not interact. This structure is controversial because it contradicts functional studies and known structures of similar ABDs from other muscle proteins. Here, we investigated the solution conformation of the dystrophin N-ABD using a very simple and elegant technique of pyrene excimer fluorescence. Using the wild-type protein, which contains two cysteines, and the corresponding single-cysteine mutants, we show that the protein is a monomer in solution and is in a closed conformation in which the two CH domains seem to interact, as observed from the excimer fluorescence of pyrene-labeled wild-type protein. Excimer fluorescence was also observed in its actin-bound form, indicating that the dystrophin N-ABD binds to F-actin in a closed conformation. Comparison of the dystrophin N-ABD conformation with other ABDs indicates that the tandem CH domains in general may be monomeric in solution and predominantly occur in closed conformation, whereas their actin-bound conformations may differ.
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Microdystrophin ameliorates muscular dystrophy in the canine model of duchenne muscular dystrophy. Mol Ther 2013; 21:750-7. [PMID: 23319056 DOI: 10.1038/mt.2012.283] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Dystrophin deficiency results in lethal Duchenne muscular dystrophy (DMD). Substituting missing dystrophin with abbreviated microdystrophin has dramatically alleviated disease in mouse DMD models. Unfortunately, translation of microdystrophin therapy has been unsuccessful in dystrophic dogs, the only large mammalian model. Approximately 70% of the dystrophin-coding sequence is removed in microdystrophin. Intriguingly, loss of ≥50% dystrophin frequently results in severe disease in patients. To test whether the small gene size constitutes a fundamental design error for large mammalian muscle, we performed a comprehensive study using 22 dogs (8 normal and 14 dystrophic). We delivered the ΔR2-15/ΔR18-19/ΔR20-23/ΔC microdystrophin gene to eight extensor carpi ulnaris (ECU) muscles in six dystrophic dogs using Y713F tyrosine mutant adeno-associated virus (AAV)-9 (2.6 × 10(13) viral genome (vg) particles/muscle). Robust expression was observed 2 months later despite T-cell infiltration. Major components of the dystrophin-associated glycoprotein complex (DGC) were restored by microdystrophin. Treated muscle showed less inflammation, fibrosis, and calcification. Importantly, therapy significantly preserved muscle force under the stress of repeated cycles of eccentric contraction. Our results have established the proof-of-concept for microdystrophin therapy in dystrophic muscles of large mammals and set the stage for clinical trial in human patients.
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Momma K, Noguchi S, Malicdan MCV, Hayashi YK, Minami N, Kamakura K, Nonaka I, Nishino I. Rimmed vacuoles in Becker muscular dystrophy have similar features with inclusion myopathies. PLoS One 2012; 7:e52002. [PMID: 23251671 PMCID: PMC3522649 DOI: 10.1371/journal.pone.0052002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Accepted: 11/09/2012] [Indexed: 11/18/2022] Open
Abstract
Rimmed vacuoles in myofibers are thought to be due to the accumulation of autophagic vacuoles, and can be characteristic in certain myopathies with protein inclusions in myofibers. In this study, we performed a detailed clinical, molecular, and pathological characterization of Becker muscular dystrophy patients who have rimmed vacuoles in muscles. Among 65 Becker muscular dystrophy patients, we identified 12 patients who have rimmed vacuoles and 11 patients who have deletions in exons 45–48 in DMD gene. All patients having rimmed vacuoles showed milder clinical features compared to those without rimmed vacuoles. Interestingly, the rimmed vacuoles in Becker muscular dystrophy muscles seem to represent autophagic vacuoles and are also associated with polyubiquitinated protein aggregates. These findings support the notion that rimmed vacuoles can appear in Becker muscular dystrophy, and may be related to the chronic changes in muscle pathology induced by certain mutations in the DMD gene.
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Affiliation(s)
- Kazunari Momma
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
- Department of Neurology, National Defense Medical College, Saitama, Japan
| | - Satoru Noguchi
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
- * E-mail:
| | - May Christine V. Malicdan
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Yukiko K. Hayashi
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Narihiro Minami
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Keiko Kamakura
- Department of Neurology, National Defense Medical College, Saitama, Japan
| | - Ikuya Nonaka
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Ichizo Nishino
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
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Sarkis J, Vié V, Winder SJ, Renault A, Le Rumeur E, Hubert JF. Resisting sarcolemmal rupture: dystrophin repeats increase membrane-actin stiffness. FASEB J 2012; 27:359-67. [PMID: 23033320 DOI: 10.1096/fj.12-208967] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Dystrophin is an essential part of a membrane protein complex that provides flexible support to muscle fiber membranes. Loss of dystrophin function leads to membrane fragility and muscle-wasting disease. Given the importance of cytoskeletal interactions in strengthening the sarcolemma, we have focused on actin-binding domain 2 of human dystrophin, constituted by repeats 11 to 15 of the central domain (DYS R11-15). We previously showed that DYS R11-15 also interacts with membrane lipids. We investigated the shear elastic constant (μ) and the surface viscosity (η(s)) of Langmuir phospholipid monolayers mimicking the inner leaflet of the sarcolemma in the presence of DYS R11-15 and actin. The initial interaction of 100 nM DYS R11-15 with the monolayers slightly modifies their rheological properties. Injection of 0.125 μM filamentous actin leads to a strong increase of μ and η(s,) from 0 to 5.5 mN/m and 2.4 × 10(-4) N · s/m, respectively. These effects are specific to DYS R11-15, require filamentous actin, and depend on phospholipid nature and lateral surface pressure. These findings suggest that the central domain of dystrophin contributes significantly to the stiffness and the stability of the sarcolemma through its simultaneous interactions with the cytoskeleton and lipid membrane. This mechanical link is likely to be a major contributing factor to the shock absorber function of dystrophin and muscle sarcolemmal integrity on mechanical stress.
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Affiliation(s)
- Joe Sarkis
- Université Européenne de Bretagne, Rennes, France
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Exon edited dystrophin rods in the hinge 3 region. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2012; 1824:1080-9. [DOI: 10.1016/j.bbapap.2012.06.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2011] [Revised: 06/19/2012] [Accepted: 06/20/2012] [Indexed: 01/12/2023]
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Muthu M, Richardson KA, Sutherland-Smith AJ. The crystal structures of dystrophin and utrophin spectrin repeats: implications for domain boundaries. PLoS One 2012; 7:e40066. [PMID: 22911693 PMCID: PMC3401230 DOI: 10.1371/journal.pone.0040066] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2012] [Accepted: 05/31/2012] [Indexed: 11/18/2022] Open
Abstract
Dystrophin and utrophin link the F-actin cytoskeleton to the cell membrane via an associated glycoprotein complex. This functionality results from their domain organization having an N-terminal actin-binding domain followed by multiple spectrin-repeat domains and then C-terminal protein-binding motifs. Therapeutic strategies to replace defective dystrophin with utrophin in patients with Duchenne muscular dystrophy require full-characterization of both these proteins to assess their degree of structural and functional equivalence. Here the high resolution structures of the first spectrin repeats (N-terminal repeat 1) from both dystrophin and utrophin have been determined by x-ray crystallography. The repeat structures both display a three-helix bundle fold very similar to one another and to homologous domains from spectrin, α-actinin and plectin. The utrophin and dystrophin repeat structures reveal the relationship between the structural domain and the canonical spectrin repeat domain sequence motif, showing the compact structural domain of spectrin repeat one to be extended at the C-terminus relative to its previously defined sequence repeat. These structures explain previous in vitro biochemical studies in which extending dystrophin spectrin repeat domain length leads to increased protein stability. Furthermore we show that the first dystrophin and utrophin spectrin repeats have no affinity for F-actin in the absence of other domains.
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Affiliation(s)
- Muralidharan Muthu
- Institute of Molecular BioSciences, Massey University, Palmerston North, New Zealand
| | - Kylie A. Richardson
- Institute of Molecular BioSciences, Massey University, Palmerston North, New Zealand
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Yokota T, Duddy W, Echigoya Y, Kolski H. Exon skipping for nonsense mutations in Duchenne muscular dystrophy: too many mutations, too few patients? Expert Opin Biol Ther 2012; 12:1141-52. [PMID: 22650324 DOI: 10.1517/14712598.2012.693469] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Duchenne muscular dystrophy (DMD), one of the most common and lethal genetic disorders, is caused by mutations of the dystrophin gene. Removal of an exon or of multiple exons using antisense molecules has been demonstrated to allow synthesis of truncated 'Becker muscular dystrophy-like' dystrophin. AREAS COVERED Approximately 15% of DMD cases are caused by a nonsense mutation. Although patient databases have previously been surveyed for applicability to each deletion mutation pattern, this is not so for nonsense mutations. Here, we examine the world-wide database containing notations for more than 1200 patients with nonsense mutations. Approximately 47% of nonsense mutations can be potentially treated with single exon skipping, rising to 90% with double exon skipping, but to reach this proportion requires the development of exon skipping molecules targeting some 68 of dystrophin's 79 exons, with patient numbers spread thinly across those exons. In this review, we discuss progress and remaining hurdles in exon skipping and an alternative strategy, stop-codon readthrough. EXPERT OPINION Antisense-mediated exon skipping therapy is targeted highly at the individual patient and is a clear example of personalized medicine. An efficient regulatory path for drug approval will be a key to success.
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Affiliation(s)
- Toshifumi Yokota
- University of Alberta, Department of Medical Genetics, School of Human Development, Faculty of Medicine and Dentistry, 829 Medical Sciences Building, Edmonton, AB T6G 2H7, Canada.
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Singh SM, Molas JF, Kongari N, Bandi S, Armstrong GS, Winder SJ, Mallela KM. Thermodynamic stability, unfolding kinetics, and aggregation of the N-terminal actin-binding domains of utrophin and dystrophin. Proteins 2012; 80:1377-92. [PMID: 22275054 PMCID: PMC3439503 DOI: 10.1002/prot.24033] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Revised: 12/21/2011] [Accepted: 01/02/2012] [Indexed: 12/12/2022]
Abstract
Muscular dystrophy (MD) is the most common genetic lethal disorder in children. Mutations in dystrophin trigger the most common form of MD, Duchenne, and its allelic variant Becker MD. Utrophin is the closest homologue and has been shown to compensate for the loss of dystrophin in human disease animal models. However, the structural and functional similarities and differences between utrophin and dystrophin are less understood. Both proteins interact with actin through their N-terminal actin-binding domain (N-ABD). In this study, we examined the thermodynamic stability and aggregation of utrophin N-ABD and compared with that of dystrophin. Our results show that utrophin N-ABD has spectroscopic properties similar to dystrophin N-ABD. However, utrophin N-ABD has decreased denaturant and thermal stability, unfolds faster, and is correspondingly more susceptible to proteolysis, which might account for its decreased in vivo half-life compared to dystrophin. In addition, utrophin N-ABD aggregates to a lesser extent compared with dystrophin N-ABD, contrary to the general behavior of proteins in which decreased stability enhances protein aggregation. Despite these differences in stability and aggregation, both proteins exhibit deleterious effects of mutations. When utrophin N-ABD mutations analogous in position to the dystrophin disease-causing mutations were generated, they behaved similarly to dystrophin mutants in terms of decreased stability and the formation of cross-β aggregates, indicating a possible role for utrophin mutations in disease mechanisms.
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Affiliation(s)
- Surinder M. Singh
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | - Justine F. Molas
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | - Narsimulu Kongari
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | - Swati Bandi
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | - Geoffrey S. Armstrong
- Department of Chemistry and Biochemistry, University of Colorado at Boulder, Boulder, Colorado 80309, USA
| | - Steve J. Winder
- Department of Biomedical Science, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
| | - Krishna M.G. Mallela
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
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31
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Lin AY, Prochniewicz E, Henderson DM, Li B, Ervasti JM, Thomas DD. Impacts of dystrophin and utrophin domains on actin structural dynamics: implications for therapeutic design. J Mol Biol 2012; 420:87-98. [PMID: 22504225 DOI: 10.1016/j.jmb.2012.04.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Revised: 03/26/2012] [Accepted: 04/02/2012] [Indexed: 11/26/2022]
Abstract
We have used time-resolved phosphorescence anisotropy (TPA) of actin to evaluate domains of dystrophin and utrophin, with implications for gene therapy in muscular dystrophy. Dystrophin and its homolog utrophin bind to cytoskeletal actin to form mechanical linkages that prevent muscular damage. Because these proteins are too large for most gene therapy vectors, much effort is currently devoted to smaller constructs. We previously used TPA to show that both dystrophin and utrophin have a paradoxical effect on actin rotational dynamics-restricting amplitude while increasing rate, thus increasing resilience, with utrophin more effective than dystrophin. Here, we have evaluated individual domains of these proteins. We found that a "mini-dystrophin," lacking one of the two actin-binding domains, is less effective than dystrophin in regulating actin dynamics, correlating with its moderate effectiveness in rescuing the dystrophic phenotype in mice. In contrast, we found that a "micro-utrophin," with more extensive internal deletions, is as effective as full-length dystrophin in the regulation of actin dynamics. Each of utrophin's actin-binding domains promotes resilience in actin, while dystrophin constructs require the presence of both actin-binding domains and the C-terminal domain for full function. This work supports the use of a utrophin template for gene or protein therapy designs. Resilience of the actin-protein complex, measured by TPA, correlates remarkably well with previous reports of functional rescue by dystrophin and utrophin constructs in mdx mice. We propose the use of TPA as an in vitro method to aid in the design and testing of emerging gene therapy constructs.
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Affiliation(s)
- Ava Yun Lin
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
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Goyenvalle A, Wright J, Babbs A, Wilkins V, Garcia L, Davies KE. Engineering multiple U7snRNA constructs to induce single and multiexon-skipping for Duchenne muscular dystrophy. Mol Ther 2012; 20:1212-21. [PMID: 22354379 DOI: 10.1038/mt.2012.26] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is a fatal muscle wasting disorder caused by mutations in the dystrophin gene. Antisense-mediated exon skipping is one of the most promising approaches for the treatment of DMD but still faces personalized medicine challenges as different mutations found in DMD patients require skipping of different exons. However, 70% of DMD patients harbor dystrophin gene deletions in a mutation-rich area or "hot-spot" in the central genomic region. In this study, we have developed 11 different U7 small-nuclear RNA, to shuttle antisense sequences designed to mask key elements involved in the splicing of exons 45 to 55. We demonstrate that these constructs induce efficient exon skipping both in vitro in DMD patients' myoblasts and in vivo in human DMD (hDMD) mice and that they can be combined into a single vector to achieve a multi skipping of at least 3 exons. These very encouraging results provide proof of principle that efficient multiexon-skipping can be achieved using adeno-associated viral (AAV) vectors encoding multiple U7 small-nuclear RNAs (U7snRNAs), offering therefore very promising tools for clinical treatment of DMD.
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Affiliation(s)
- Aurélie Goyenvalle
- MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
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Henderson DM, Lin AY, Thomas DD, Ervasti JM. The carboxy-terminal third of dystrophin enhances actin binding activity. J Mol Biol 2011; 416:414-24. [PMID: 22226838 DOI: 10.1016/j.jmb.2011.12.040] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Revised: 12/19/2011] [Accepted: 12/20/2011] [Indexed: 10/14/2022]
Abstract
Dystrophin is an actin binding protein that is thought to stabilize the cardiac and skeletal muscle cell membranes during contraction. Here, we investigated the contributions of each dystrophin domain to actin binding function. Cosedimentation assays and pyrene-actin fluorescence experiments confirmed that a fragment spanning two-thirds of the dystrophin molecule [from N-terminal actin binding domain (ABD) 1 through ABD2] bound actin filaments with high affinity and protected filaments from forced depolymerization, but was less effective in both assays than full-length dystrophin. While a construct encoding the C-terminal third of dystrophin displayed no specific actin binding activity or competition with full-length dystrophin, our data show that it confers an unexpected regulation of actin binding by the N-terminal two-thirds of dystrophin when present in cis. Time-resolved phosphorescence anisotropy experiments demonstrated that the presence of the C-terminal third of dystrophin in cis also influences actin interaction by restricting actin rotational amplitude. We propose that the C-terminal region of dystrophin allosterically stabilizes an optimal actin binding conformation of dystrophin.
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Affiliation(s)
- Davin M Henderson
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
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Anthony K, Cirak S, Torelli S, Tasca G, Feng L, Arechavala-Gomeza V, Armaroli A, Guglieri M, Straathof CS, Verschuuren JJ, Aartsma-Rus A, Helderman-van den Enden P, Bushby K, Straub V, Sewry C, Ferlini A, Ricci E, Morgan JE, Muntoni F. Dystrophin quantification and clinical correlations in Becker muscular dystrophy: implications for clinical trials. ACTA ACUST UNITED AC 2011; 134:3547-59. [PMID: 22102647 DOI: 10.1093/brain/awr291] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Duchenne muscular dystrophy is caused by mutations in the DMD gene that disrupt the open reading frame and prevent the full translation of its protein product, dystrophin. Restoration of the open reading frame and dystrophin production can be achieved by exon skipping using antisense oligonucleotides targeted to splicing elements. This approach aims to transform the Duchenne muscular dystrophy phenotype to that of the milder disorder, Becker muscular dystrophy, typically caused by in-frame dystrophin deletions that allow the production of an internally deleted but partially functional dystrophin. There is ongoing debate regarding the functional properties of the different internally deleted dystrophins produced by exon skipping for different mutations; more insight would be valuable to improve and better predict the outcome of exon skipping clinical trials. To this end, we have characterized the clinical phenotype of 17 patients with Becker muscular dystrophy harbouring in-frame deletions relevant to on-going or planned exon skipping clinical trials for Duchenne muscular dystrophy and correlated it to the levels of dystrophin, and dystrophin-associated protein expression. The cohort of 17 patients, selected exclusively on the basis of their genotype, included 4 asymptomatic, 12 mild and 1 severe patient. All patients had dystrophin levels of >40% of control and significantly higher dystrophin (P = 0.013), β-dystroglycan (P = 0.025) and neuronal nitric oxide synthase (P = 0.034) expression was observed in asymptomatic individuals versus symptomatic patients with Becker muscular dystrophy. Furthermore, grouping the patients by deletion, patients with Becker muscular dystrophy with deletions with an end-point of exon 51 (the skipping of which could rescue the largest group of Duchenne muscular dystrophy deletions) showed significantly higher dystrophin levels (P = 0.034) than those with deletions ending with exon 53. This is the first quantitative study on both dystrophin and dystrophin-associated protein expression in patients with Becker muscular dystrophy with deletions relevant for on-going exon skipping trials in Duchenne muscular dystrophy. Taken together, our results indicate that all varieties of internally deleted dystrophin assessed in this study have the functional capability to provide a substantial clinical benefit to patients with Duchenne muscular dystrophy.
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Affiliation(s)
- Karen Anthony
- The Dubowitz Neuromuscular Centre, UCL, Institute of Child Health, London WC1N 1EH, UK
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