Myonuclear domain-associated and central nucleation-dependent spatial restriction of dystrophin protein expression in a novel DMD mouse model

bioRxiv (Cold Spring Harbor Laboratory)

Abstract

Abstract The restoration of uniformly-distributed dystrophin protein expression is an important consideration for the development of advanced therapeutics for Duchenne muscular dystrophy (DMD). To explore this concept, we generated a novel genetic mouse model ( mdx52-Xist Δhs ) that expresses variable, and non-uniformly distributed, dystrophin protein from birth as a consequence of skewed X-chromosome inactivation. mdx52-Xist Δhs myofibers are heterokaryons containing a mixture of myonuclei expressing either wild-type or mutant dystrophin alleles in a mutually exclusive manner, resulting in dystrophin protein being spatially restricted to corresponding dystrophin-expressing myonuclear domains. This phenotype models the situation in female DMD carriers, and dystrophic muscle in which dystrophin has been incompletely restored by partially-effective experimental therapeutics. Total dystrophin expression increased in aged (60-week-old) mdx52-Xist Δhs mice relative to 6-week-old adults, suggestive of an accumulation of dystrophin-expressing myonuclei through positive selection, although this was insufficient to resolve sarcolemmal dystrophin patchiness. Nevertheless, compared to mice expressing no dystrophin, non-uniformly-distributed dystrophin was protective against pathology-related muscle turnover in an expression-level-dependent manner in both adult and aged mdx52-Xist Δhs mice. Systematic classification of isolated mdx52-Xist Δhs myofibers revealed profound differences associated with central nucleation, with dystrophin found to be translationally repressed in centrally-nucleated myofibers and myofiber segments. These findings have important implications for the development of dystrophin restoration therapies.

Authors 11

1. Katarzyna Chwalenia

   University of Oxford

   Affiliation as printed

   University of Oxford;

   Institute of Developmental and Regenerative Medicine, University of Oxford, IMS-Tetsuya Nakamura Building, Old Road Campus, Roosevelt Dr, Headington, Oxford OX3 7TY

2. Vivi-Yun Feng

   University of Oxford · Freie Universität Berlin

   Affiliation as printed

   University of Oxford;

   Freie Universität Berlin, Kaiserswerther Str. 16-18, 14195 Berlin, Germany

   Institute of Developmental and Regenerative Medicine, University of Oxford, IMS-Tetsuya Nakamura Building, Old Road Campus, Roosevelt Dr, Headington, Oxford OX3 7TY

3. Nicole Hemmer

   University of Oxford · University of Tübingen

   Affiliation as printed

   University of Oxford;

   Eberhard-Karls-Universität Tübingen, Geschwister-Scholl-Platz, 7207 Tübingen, Germany

   Institute of Developmental and Regenerative Medicine, University of Oxford, IMS-Tetsuya Nakamura Building, Old Road Campus, Roosevelt Dr, Headington, Oxford OX3 7TY

4. John C. W. Hildyard

   Royal Veterinary College

   Affiliation as printed

   Royal Veterinary College;

   Comparative Neuromuscular Diseases Laboratory, Department of Clinical Science and Services, Royal Veterinary College, Camden, London, NW1 0TU, UK

5. Liberty E. Roskrow

   Royal Veterinary College

   Affiliation as printed

   Royal Veterinary College;

   Comparative Neuromuscular Diseases Laboratory, Department of Clinical Science and Services, Royal Veterinary College, Camden, London, NW1 0TU, UK

6. Richard J. Piercy

   Royal Veterinary College

   Affiliation as printed

   Royal Veterinary College;

   Comparative Neuromuscular Diseases Laboratory, Department of Clinical Science and Services, Royal Veterinary College, Camden, London, NW1 0TU, UK

7. Eric T. Wang

   University of Florida

   Affiliation as printed

   University of Florida;

   Department of Molecular Genetics & Microbiology, Center for NeuroGenetics, Genetics Institute, University of Florida, Gainesville, FL, USA

8. Annemieke M Aartsma-Rus Aachen Department of Human Genetics

   Leiden University Medical Center

   Affiliation as printed

   Leiden University Medical Center

   Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands

9. Maaike van Putten Aachen Department of Human Genetics

   Leiden University Medical Center

   Affiliation as printed

   Leiden University Medical Center

   Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands

10. Matthew J. A. Wood

    University of Oxford · University of Tübingen

    Affiliation as printed

    University of Oxford;

    Department of Paediatrics, University of Oxford, South Parks Road, Oxford, OX 3QX, UK

    Eberhard-Karls-Universität Tübingen, Geschwister-Scholl-Platz, 7207 Tübingen, Germany

    MDUK Oxford Neuromuscular Centre, South Parks Road, Oxford, UK

11. Thomas C. Roberts corresponding

    University of Oxford

    Affiliation as printed

    University of Oxford;

    Institute of Developmental and Regenerative Medicine, University of Oxford, IMS-Tetsuya Nakamura Building, Old Road Campus, Roosevelt Dr, Headington, Oxford OX3 7TY

    MDUK Oxford Neuromuscular Centre, South Parks Road, Oxford, UK