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Breukel A, Willmann R, Adcock K, Méjat A, Meijer I, Ferreiro A. The European Neuromuscular Centre has celebrated its 30th anniversary! Neuromuscul Disord 2023; 33:285-287. [PMID: 36842302 DOI: 10.1016/j.nmd.2023.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 01/26/2023] [Indexed: 01/30/2023]
Affiliation(s)
- Alexandra Breukel
- European Neuromuscular Centre, Lt. Generaal van Heutszlaan 6, Baarn 3743JN, The Netherlands.
| | - Raffaella Willmann
- European Neuromuscular Centre, Lt. Generaal van Heutszlaan 6, Baarn 3743JN, The Netherlands
| | - Kate Adcock
- European Neuromuscular Centre, Lt. Generaal van Heutszlaan 6, Baarn 3743JN, The Netherlands
| | - Alexandre Méjat
- European Neuromuscular Centre, Lt. Generaal van Heutszlaan 6, Baarn 3743JN, The Netherlands
| | - Ingeborg Meijer
- European Neuromuscular Centre, Lt. Generaal van Heutszlaan 6, Baarn 3743JN, The Netherlands
| | - Ana Ferreiro
- European Neuromuscular Centre, Lt. Generaal van Heutszlaan 6, Baarn 3743JN, The Netherlands
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2
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Smits A, Annaert P, Cavallaro G, De Cock PAJG, de Wildt SN, Kindblom JM, Lagler FB, Moreno C, Pokorna P, Schreuder MF, Standing JF, Turner MA, Vitiello B, Zhao W, Weingberg AM, Willmann R, van den Anker J, Allegaert K. Current knowledge, challenges and innovations in developmental pharmacology: A combined conect4children Expert Group and European Society for Developmental, Perinatal and Paediatric Pharmacology White Paper. Br J Clin Pharmacol 2022; 88:4965-4984. [PMID: 34180088 PMCID: PMC9787161 DOI: 10.1111/bcp.14958] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 05/22/2021] [Accepted: 05/30/2021] [Indexed: 12/30/2022] Open
Abstract
Developmental pharmacology describes the impact of maturation on drug disposition (pharmacokinetics, PK) and drug effects (pharmacodynamics, PD) throughout the paediatric age range. This paper, written by a multidisciplinary group of experts, summarizes current knowledge, and provides suggestions to pharmaceutical companies, regulatory agencies and academicians on how to incorporate the latest knowledge regarding developmental pharmacology and innovative techniques into neonatal and paediatric drug development. Biological aspects of drug absorption, distribution, metabolism and excretion throughout development are summarized. Although this area made enormous progress during the last two decades, remaining knowledge gaps were identified. Minimal risk and burden designs allow for optimally informative but minimally invasive PK sampling, while concomitant profiling of drug metabolites may provide additional insight in the unique PK behaviour in children. Furthermore, developmental PD needs to be considered during drug development, which is illustrated by disease- and/or target organ-specific examples. Identifying and testing PD targets and effects in special populations, and application of age- and/or population-specific assessment tools are discussed. Drug development plans also need to incorporate innovative techniques such as preclinical models to study therapeutic strategies, and shift from sequential enrolment of subgroups, to more rational designs. To stimulate appropriate research plans, illustrations of specific PK/PD-related as well as drug safety-related challenges during drug development are provided. The suggestions made in this joint paper of the Innovative Medicines Initiative conect4children Expert group on Developmental Pharmacology and the European Society for Developmental, Perinatal and Paediatric Pharmacology, should facilitate all those involved in drug development.
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Affiliation(s)
- Anne Smits
- Department of Development and Regeneration, KU Leuven, Leuven, Belgium.,Neonatal intensive Care unit, University Hospitals Leuven, Leuven, Belgium
| | - Pieter Annaert
- Drug Delivery and Disposition, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Giacomo Cavallaro
- Neonatal intensive care unit, Fondazione IRCCS Ca' Grande Ospedale Maggiore Policlinico, Milan, Italy
| | - Pieter A J G De Cock
- Department of Pediatric Intensive Care, Ghent University Hospital, Ghent, Belgium.,Heymans Institute of Pharmacology, Ghent University, Ghent, Belgium.,Department of Pharmacy, Ghent University Hospital, Ghent, Belgium
| | - Saskia N de Wildt
- Intensive Care and Pediatric Surgery, Erasmus MC-Sophia Children's Hospital, Rotterdam, the Netherlands.,Department of Pharmacology and Toxicology, Radboud Institute Health Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Jenny M Kindblom
- Pediatric Clinical Research Center, Queen Silvia Children's Hospital, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Florian B Lagler
- Institute for Inherited Metabolic Diseases and Department of Pediatrics, Paracelsus Medical University, Clinical Research Center Salzburg, Salzburg, Austria
| | - Carmen Moreno
- Institute of Psychiatry and Mental Health, Child and Adolescent Psychiatry Department, Hospital General Universitario Gregorio Marañón, School of Medicine, Universidad Complutense, IiSGM, CIBERSAM, Madrid, Spain
| | - Paula Pokorna
- Intensive Care and Pediatric Surgery, Erasmus MC-Sophia Children's Hospital, Rotterdam, the Netherlands.,Department of Pharmacology, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic.,Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic.,Department of Physiology and Pharmacology, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden
| | - Michiel F Schreuder
- Department of Pediatric Nephrology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, Amalia Children's Hospital, Nijmegen, the Netherlands
| | - Joseph F Standing
- UCL Great Ormond Street Institute of Child Health, London, UK.,Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK.,Institute for Infection and Immunity, St George's, University of London, London, UK
| | - Mark A Turner
- Department of Women's and Children's Health, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool Health Partners, Liverpool, UK
| | - Benedetto Vitiello
- Division of Child and Adolescent Neuropsychiatry, Department of Public Health and Pediatrics, University of Torino, Torino, Italy
| | - Wei Zhao
- Department of Clinical Pharmacy, Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, China.,Department of Pharmacy, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Jinan, China.,Clinical Research Centre, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Jinan, China
| | | | | | - John van den Anker
- Intensive Care and Pediatric Surgery, Erasmus MC-Sophia Children's Hospital, Rotterdam, the Netherlands.,Paediatric Pharmacology and Pharmacometrics, University Children's Hospital Basel (UKBB), University of Basel, Basel, Switzerland.,Division of Clinical Pharmacology, Children's National Hospital, Washington, DC, USA
| | - Karel Allegaert
- Department of Development and Regeneration, KU Leuven, Leuven, Belgium.,Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium.,Department of Hospital Pharmacy, Erasmus MC University Medical Center, Rotterdam, the Netherlands
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3
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Abstract
Muscular dystrophies (MDs) encompass a wide variety of inherited disorders that are characterized by loss of muscle tissue associated with a progressive reduction in muscle function. With a cure lacking for MDs, preclinical developments of therapeutic approaches depend on well-characterized animal models that recapitulate the specific pathology in patients. The mouse is the most widely and extensively used model for MDs, and it has played a key role in our understanding of the molecular mechanisms underlying MD pathogenesis. This has enabled the development of therapeutic strategies. Owing to advancements in genetic engineering, a wide variety of mouse models are available for the majority of MDs. Here, we summarize the characteristics of the most commonly used mouse models for a subset of highly studied MDs, collated into a table. Together with references to key publications describing these models, this brief but detailed overview would be useful for those interested in, or working with, mouse models of MD.
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Affiliation(s)
- Maaike van Putten
- Leiden University Medical Center, Department of Human Genetics, Leiden, 2333 ZA, The Netherlands
| | - Erin M Lloyd
- The University of Western Australia, School of Human Sciences, Perth 6009, Australia
| | - Jessica C de Greef
- Leiden University Medical Center, Department of Human Genetics, Leiden, 2333 ZA, The Netherlands
| | - Vered Raz
- Leiden University Medical Center, Department of Human Genetics, Leiden, 2333 ZA, The Netherlands
| | | | - Miranda D Grounds
- The University of Western Australia, School of Human Sciences, Perth 6009, Australia
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4
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Willmann R, Lee J, Turner C, Nagaraju K, Aartsma-Rus A, Wells DJ, Wagner KR, Csimma C, Straub V, Grounds MD, De Luca A. Improving translatability of preclinical studies for neuromuscular disorders: lessons from the TREAT-NMD Advisory Committee for Therapeutics (TACT). Dis Model Mech 2020; 13:13/2/dmm042903. [PMID: 32066568 PMCID: PMC7044444 DOI: 10.1242/dmm.042903] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Clinical trials for rare neuromuscular diseases imply, among other investments, a high emotional burden for the whole disease community. Translation of data from preclinical studies to justify any clinical trial must be carefully pondered in order to minimize the risk of clinical trial withdrawal or failure. A rigorous distinction between proof-of-concept and preclinical efficacy studies using animal models is key to support the rationale of a clinical trial involving patients. This Review evaluates the experience accumulated by the TREAT-NMD Advisory Committee for Therapeutics, which provides detailed constructive feedback on clinical proposals for neuromuscular diseases submitted by researchers in both academia and industry, and emphasizes that a timely critical review of preclinical efficacy data from animal models, including biomarkers for specific diseases, combined with adherence to existing guidelines and standard protocols, can significantly help to de-risk clinical programs and prevent disappointments and costly engagement.
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Affiliation(s)
- Raffaella Willmann
- Swiss Foundation for Research on Muscle Diseases, 2016 Cortaillod, Switzerland
| | - Joanne Lee
- John Walton Muscular Dystrophy Research Centre, Centre for Life, Newcastle University and Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne NE7 7DN, UK
| | - Cathy Turner
- John Walton Muscular Dystrophy Research Centre, Centre for Life, Newcastle University and Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne NE7 7DN, UK
| | - Kanneboyina Nagaraju
- School of Pharmacy and Pharmaceutical Sciences, Binghamton University, New York, NY 13902-6000, USA
| | - Annemieke Aartsma-Rus
- John Walton Muscular Dystrophy Research Centre, Centre for Life, Newcastle University and Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne NE7 7DN, UK.,Department of Human Genetics, Leiden University Medical Center, Leiden, 2300 RC, the Netherlands
| | - Dominic J Wells
- Neuromuscular Disease Group, Royal Veterinary College, London NW1 0TU, UK
| | - Kathryn R Wagner
- Center for Genetic Muscle Disorders, Kennedy Krieger Institute and the Departments of Neurology and Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
| | | | - Volker Straub
- John Walton Muscular Dystrophy Research Centre, Centre for Life, Newcastle University and Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne NE7 7DN, UK
| | - Miranda D Grounds
- School of Human Sciences, The University of Western Australia, Perth, WA 6009, Australia
| | - Annamaria De Luca
- Unit of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari Aldo Moro, 70125 Bari, Italy
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5
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Willmann R, Gordish-Dressman H, Meinen S, Rüegg MA, Yu Q, Nagaraju K, Kumar A, Girgenrath M, Coffey CBM, Cruz V, Van Ry PM, Bogdanik L, Lutz C, Rutkowski A, Burkin DJ. Improving Reproducibility of Phenotypic Assessments in the DyW Mouse Model of Laminin-α2 Related Congenital Muscular Dystrophy. J Neuromuscul Dis 2019; 4:115-126. [PMID: 28550268 PMCID: PMC5467719 DOI: 10.3233/jnd-170217] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Laminin-α2 related Congenital Muscular Dystrophy (LAMA2-CMD) is a progressive muscle disease caused by partial or complete deficiency of laminin-211, a skeletal muscle extracellular matrix protein. In the last decade, basic science research has queried underlying disease mechanisms in existing LAMA2-CMD murine models and identified possible clinical targets and pharmacological interventions. Experimental rigor in preclinical studies is critical to efficiently and accurately quantify both negative and positive results, degree of efficiency of potential therapeutics and determine whether to move a compound forward for additional preclinical testing. In this review, we compare published available data measured to assess three common parameters in the widely used mouse model DyW, that mimics LAMA2-CMD, we quantify variability and analyse its possible sources. Finally, on the basis of this analysis, we suggest standard set of assessments and the use of available standardized protocols, to reduce variability of outcomes in the future and to improve the value of preclinical research.
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Affiliation(s)
- Raffaella Willmann
- Swiss Foundation for Research on Muscle Diseases, Cortaillod, Switzerland.,Biozentrum, University of Basel, Basel, Switzerland
| | | | | | | | - Qing Yu
- Center for Genetic Medicine Research, Children's National Medical Center, Washington, DC, USA
| | - Kanneboyina Nagaraju
- Center for Genetic Medicine Research, Children's National Medical Center, Washington, DC, USA
| | - Ayar Kumar
- Department of Health Sciences, Boston University, Boston, MA, USA
| | | | - Caroline B M Coffey
- Department of Pharmacology, University of Nevada School of Medicine, Reno, NV, USA
| | - Vivian Cruz
- Department of Pharmacology, University of Nevada School of Medicine, Reno, NV, USA
| | - Pam M Van Ry
- Department of Pharmacology, University of Nevada School of Medicine, Reno, NV, USA
| | | | | | - Anne Rutkowski
- Cure Congenital Muscular Dystrophy and Kaiser SCPMG, Los Angeles, CA, USA
| | - Dean J Burkin
- Department of Pharmacology, University of Nevada School of Medicine, Reno, NV, USA
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6
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Ambrosini A, Quinlivan R, Sansone VA, Meijer I, Schrijvers G, Tibben A, Padberg G, de Wit M, Sterrenburg E, Mejat A, Breukel A, Rataj M, Lochmüller H, Willmann R. "Be an ambassador for change that you would like to see": a call to action to all stakeholders for co-creation in healthcare and medical research to improve quality of life of people with a neuromuscular disease. Orphanet J Rare Dis 2019; 14:126. [PMID: 31174585 PMCID: PMC6555994 DOI: 10.1186/s13023-019-1103-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2019] [Accepted: 05/21/2019] [Indexed: 01/08/2023] Open
Abstract
Background Patient and public involvement for co-creation is increasingly recognized as a valuable strategy to develop healthcare research targeting patients’ real needs. However, its practical implementation is not as advanced and unanimously accepted as it could be, due to cultural differences and complexities of managing healthcare programs and clinical studies, especially in the rare disease field. Main body The European Neuromuscular Centre, a European foundation of patient organizations, involved its key stakeholders in a special workshop to investigate the position of the neuromuscular patient community with respect to healthcare and medical research to identify and address gaps and bottlenecks. The workshop took place in Milan (Italy) on January 19–20, 2018, involving 45 participants who were mainly representatives of the patient community, but also included experts from clinical centers, industry and regulatory bodies. In order to provide practical examples and constructive suggestions, specific topics were identified upfront. The first set of issues concerned the quality of life at specific phases of a patient’s life, such as at the time of diagnosis or during pediatric to adult transition, and patient involvement in medical research on activities in daily living including patient reported outcome measures. The second set of issues concerned the involvement of patients in the management of clinical research tools, such as registries and biobanks, and their participation in study design or marketing authorization processes. Introductory presentations were followed by parallel working group sessions, to gain constructive contributions from all participants. The concept of shared decision making was used to ensure, in discussions, a partnership-based identification of the wishes and needs of all stakeholders involved, and the “ladder of participation” tool served as a model to evaluate the actual and the desired level of patients’ involvement in all topics addressed. A general consensus on the outcome of the meeting was collected during the final plenary session. This paper reports the outcome of the workshop and the specific suggestions derived from the analysis of the first set of topics, related to quality of life. The outcomes of the second set of topics are reported elsewhere and are only briefly summarized herein for the sake of completeness. Conclusions The neuromuscular community proved to be very active and engaged at different levels in the healthcare initiatives of interest. The workshop participants critically discussed several topics, providing practical examples where different stakeholders could play a role in making a change and bridging gaps. Overall, they indicated the need for education of all stakeholders for better communication, where everyone should become an ambassador to promote real change. Support should also come from institutions and healthcare bodies both at structural and economic level.
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Affiliation(s)
- Anna Ambrosini
- Fondazione Telethon, Via Poerio 14, 20129, Milan, Italy.
| | - Ros Quinlivan
- MRC Centre for Neuromuscular Diseases, Institute of Neurology, Queen Square, London, UK
| | - Valeria A Sansone
- NEuroMuscular Omnicentre (NEMO), Neurorehabilitation Unit, University of Milan, ASST Grande Ospedale Metropolitano Niguarda, Fondazione Serena Onlus, Milan, Italy
| | - Ingeborg Meijer
- Centre for Science and Technology Studies (CWTS), University of Leiden, Leiden, The Netherlands.,Spierziekten Nederland, Baarn, the Netherlands
| | | | - Aad Tibben
- Centre for Human and Clinical Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - George Padberg
- Centre for Human and Clinical Genetics, Leiden University Medical Centre, Leiden, The Netherlands
| | - Maarten de Wit
- Department of Medical Humanities, Amsterdam University Medical Centre, Amsterdam, The Netherlands
| | | | - Alexandre Mejat
- University of Lyon, University of Lyon1 Claude Bernard Lyon1, Institut NeuroMyoGene, CNRS UMR5310, INSERM U1217, Lyon, France
| | | | - Michal Rataj
- Polish Neuromuscular Diseases Association (PTCHNM), Warszawa, Poland
| | - Hanns Lochmüller
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Canada.,Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, Canada.,Faculty of Medicine, Department of Neuropediatrics and Muscle Disorders, Medical Center - University of Freiburg, Freiburg, Germany
| | - Raffaella Willmann
- Swiss Foundation for Research on Muscle Diseases, Cortaillod, Switzerland
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7
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Breukel A, Willmann R, Padberg G, Sterrenburg E, Meijer I. "The impact of European Neuromuscular Centre (ENMC) workshops on the neuromuscular field; 25 years on …". Neuromuscul Disord 2019; 29:330-340. [PMID: 30853171 DOI: 10.1016/j.nmd.2019.01.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 01/28/2019] [Indexed: 02/06/2023]
Abstract
Since 1992, the European Neuromuscular Centre facilitated workshops to bring experts in the field of neuromuscular disorders together. After organising more than 235 workshops, it is time to evaluate what impact these 25 years of ENMC workshops have had on the neuromuscular research field and on people affected by a neuromuscular condition. To measure this, workshop topics were retrospectively evaluated and bibliometric analyses on the citation scores of ENMC-derived publications were performed. In addition, a personalized survey was used to investigate the actual achievement and implementation of workshop deliverables. The evaluation of 25 years' workshop topics revealed a strong representation of muscular dystrophies, congenital and mitochondrial myopathies. The publications derived from ENMC workshops scored "high impact" as illustrated by the Mean Normalized Citation Score of 1.24. Also 16% of the ENMC papers belong to the top 10% best cited articles in the neuromuscular field. The main outcome of the personalised survey was that 90% of all workshop deliverables were started and either ongoing or completed. Of these deliverables, 78% were implemented in the field; bringing state-of-the-art knowledge and new collaborations to researchers and clinicians, improving designs of clinical trials and innovating tools to make accurate diagnoses.
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Affiliation(s)
- Alexandra Breukel
- European Neuromuscular Centre (ENMC), Lt. Generaal van Heutszlaan 6, Baarn 3743JN, The Netherlands.
| | - Raffaella Willmann
- Schweizerische Stiftung für die Erforschung der Muskelkrankheiten (FSRMM), Cortaillod, Switzerland
| | - George Padberg
- European Neuromuscular Centre (ENMC), Lt. Generaal van Heutszlaan 6, Baarn 3743JN, The Netherlands
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8
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Gordish-Dressman H, Willmann R, Dalle Pazze L, Kreibich A, van Putten M, Heydemann A, Bogdanik L, Lutz C, Davies K, Demonbreun AR, Duan D, Elsey D, Fukada SI, Girgenrath M, Patrick Gonzalez J, Grounds MD, Nichols A, Partridge T, Passini M, Sanarica F, Schnell FJ, Wells DJ, Yokota T, Young CS, Zhong Z, Spurney C, Spencer M, De Luca A, Nagaraju K, Aartsma-Rus A. "Of Mice and Measures": A Project to Improve How We Advance Duchenne Muscular Dystrophy Therapies to the Clinic. J Neuromuscul Dis 2019; 5:407-417. [PMID: 30198876 PMCID: PMC6218134 DOI: 10.3233/jnd-180324] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A new line of dystrophic mdx mice on the DBA/2J (D2) background has emerged as a candidate to study the efficacy of therapeutic approaches for Duchenne muscular dystrophy (DMD). These mice harbor genetic polymorphisms that appear to increase the severity of the dystropathology, with disease modifiers that also occur in DMD patients, making them attractive for efficacy studies and drug development. This workshop aimed at collecting and consolidating available data on the pathological features and the natural history of these new D2/mdx mice, for comparison with classic mdx mice and controls, and to identify gaps in information and their potential value. The overall aim is to establish guidance on how to best use the D2/mdx mouse model in preclinical studies.
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Affiliation(s)
| | | | | | | | - Maaike van Putten
- Department of Human Genetics, Leiden University Medical Center, the Netherlands
| | - Ahlke Heydemann
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, USA
| | | | | | - Kay Davies
- Department of Physiology, University of Oxford, Anatomy and Genetics, Oxford, UK
| | - Alexis R Demonbreun
- Center for Genetic Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Dongsheng Duan
- Department of Molecular Microbiology and Immunology, Department of Neurology, Department of Biomedical Sciences and Department of Bioengineering, University of Missouri, Columbia, MO, USA
| | - David Elsey
- Summit Therapeutics, Abingdon, Oxfordshire, UK
| | - So-Ichiro Fukada
- Laboratory of Molecular and Cellular Physiology, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan
| | | | | | - Miranda D Grounds
- School of Human Science, the University of Western Australia, Perth, Australia
| | | | | | | | - Francesca Sanarica
- Department of Pharmacy and Drug Sciences, Unit of Pharmacology, University of Bari "Aldo Moro", Italy
| | | | - Dominic J Wells
- Department of Comparative Biomedical Sciences, Royal Veterinary College, London, UK
| | | | - Courtney S Young
- Department of Neurology, Molecular Biology Institute, Center for Duchenne Muscular Dystrophy at UCLA, University of California, Los Angeles, CA, USA
| | | | | | - Melissa Spencer
- Department of Neurology, Molecular Biology Institute, Center for Duchenne Muscular Dystrophy at UCLA, University of California, Los Angeles, CA, USA
| | - Annamaria De Luca
- Department of Pharmacy and Drug Sciences, Unit of Pharmacology, University of Bari "Aldo Moro", Italy
| | - Kanneboyina Nagaraju
- School of Pharmacy and Pharmaceutical Sciences, Binghamton University, New York, USA
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9
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Lochmüller H, Ambrosini A, van Engelen B, Hansson M, Tibben A, Breukel A, Sterrenburg E, Schrijvers G, Meijer I, Padberg G, Peay H, Monaco L, Snape M, Lennox A, Mazzone E, Bere N, de Lemus M, Landfeldt E, Willmann R. The Position of Neuromuscular Patients in Shared Decision Making. Report from the 235th ENMC Workshop: Milan, Italy, January 19-20, 2018. J Neuromuscul Dis 2019; 6:161-172. [PMID: 30714970 DOI: 10.3233/jnd-180368] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In the era of patient-centered medicine, shared decision-making (SDM) - in which healthcare professionals and patients exchange information and preferences and jointly reach a decision - has emerged as the gold standard model for the provision of formal healthcare. Indeed, in many geographical settings, patients are frequently invited to participate in choices concerning the design and delivery of their medical management. From a clinical perspective, benefits of this type of patient involvement encompass, for example, enhanced treatment satisfaction, improved medical compliance, better health outcomes, and maintained or promoted quality of life. Yet, although the theory and enactment of SDM in healthcare are well-described in the literature [1-3], comparatively less attention has been devoted to contextualizing questions relating to if, when, and how to include patients in decisions within medical research. In this context, patient involvement would be expected to be potentially relevant for and applicable to a wide range of activities and processes, from the identification of research priorities and development of grant applications, to the design of patient information and consent procedures, formulation of interventions, identification and recruitment of study sample populations, feasibility of a clinical trial, identification, selection, and specification of endpoints and outcomes in clinical trials and observational studies, data collection and analysis, and dissemination of results. To this end, 45 clinicians, healthcare professionals, researchers, patients, caregivers, and representatives from regulatory authorities and pharmaceutical companies from 15 different countries met to discuss the level of involvement of patients with neuromuscular diseases, specifically in the following settings of medical research for neuromuscular diseases: i) registries and biobanks; ii) clinical trials; and iii) regulatory processes. In this report, we present summaries of the talks that were given during the workshop, as well as discussion outcomes from the three topic areas listed above.
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Affiliation(s)
- Hanns Lochmüller
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Canada and Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, Canada; Department of Neuropediatrics and Muscle Disorders, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany
| | | | - Baziel van Engelen
- Department of Neurology, Radboud University Medical Center, Nijmegen, the Netherlands
| | | | - Aad Tibben
- Centre for Human and Clinical Genetics, Leiden University Medical Centre, Leiden, the Netherlands
| | | | | | | | - Ingeborg Meijer
- Centre for Science and Technology Studies (CWTS), University of Leiden, Leiden, the Netherlands and Spierziekten Nederland, Baarn, the Netherlands
| | - George Padberg
- Centre for Human and Clinical Genetics, Leiden University Medical Centre, Leiden, the Netherlands
| | - Holly Peay
- RTI International, Research Triangle Park, NC, USA
| | | | | | | | - Elena Mazzone
- Department of Child Neurology, Catholic University, Rome, Italy
| | - Nathalie Bere
- Public Engagement, European Medicines Agency, London, UK
| | | | - Erik Landfeldt
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden; and Icon plc, Stockholm, Sweden
| | - Raffaella Willmann
- Swiss Foundation for Research on Muscle Diseases, Cortaillod, Switzerland
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10
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van Putten M, Aartsma-Rus A, Grounds MD, Kornegay JN, Mayhew A, Gillingwater TH, Takeda S, Rüegg MA, De Luca A, Nagaraju K, Willmann R. Update on Standard Operating Procedures in Preclinical Research for DMD and SMA Report of TREAT-NMD Alliance Workshop, Schiphol Airport, 26 April 2015, The Netherlands. J Neuromuscul Dis 2018; 5:29-34. [PMID: 29480217 PMCID: PMC5836406 DOI: 10.3233/jnd-170288] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
A workshop took place in 2015 to follow up TREAT-NMD activities dedicated to improving quality in the preclinical phase of drug development for neuromuscular diseases. In particular, this workshop adressed necessary future steps regarding common standard experimental protocols and the issue of improving the translatability of preclinical efficacy studies.
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Affiliation(s)
- Maaike van Putten
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Annemieke Aartsma-Rus
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Miranda D Grounds
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, Perth, WA, Australia
| | - Joe N Kornegay
- College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, TX, USA
| | - Anna Mayhew
- John Walton Muscular Dystrophy Research Centre, Newcastle University, Newcastle, UK
| | - Thomas H Gillingwater
- Edinburgh Medical School, Biomedical Sciences, University of Edinburgh, Edinburgh, UK
| | - Shin'ichi Takeda
- National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | | | - Annamaria De Luca
- Department of Pharmacy and Drug Sciences, Unit of Pharmacology, University of Bari, Bari, Italy
| | | | - Raffaella Willmann
- Biozentrum, University of Basel, Basel, Switzerland.,Swiss Foundation for Research on Muscle Diseases, Cortaillod, Switzerland
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Willmann R, Buccella F, De Luca A, Grounds MD, Versnel J, Vroom E, Ribeiro D, Ambrosini A, Pavlath G, Porter J, Dziewczapolski G, Dubowitz V, Lochmüller H, Campbell K, Davies K, Roth KA, Clark A, Clementi E, Nagaraju K, Goemans N, Straub V, Klein A, Aartsma-Rus A, Grounds M, Willmann R, Buccella F, van Putten M, Fries M, Sheean M, Tinsley J, Girgenrath M. 227 th ENMC International Workshop:. Neuromuscul Disord 2018; 28:185-192. [DOI: 10.1016/j.nmd.2017.11.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 11/06/2017] [Indexed: 01/31/2023]
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Willmann R, Luca AD, Nagaraju K, Rüegg MA. Best Practices and Standard Protocols as a Tool to Enhance Translation for Neuromuscular Disorders. J Neuromuscul Dis 2015; 2:113-117. [PMID: 27858730 DOI: 10.3233/jnd-140067] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Recent years witnessed an exciting increase in the number of clinical trials for neuromuscular disorders, in particular for Duchenne Muscular Dystrophy and Spinal Muscle Atrophy. Given the high emotional impact of such developments for devastating diseases with an urgent medical need, it is particularly important to justify human trials on the basis of robust preclinical studies and to avoid a waste of hopes and of funds.This review focuses the discussion on the quality in the conduct clinically-oriented preclinical assessments in rare neuromuscular disease models and on the importance in reporting of preclinical confirmatory studies. Accordingly, it invites scientists, journal publishers and funding agencies to require quality standards to improve translatability of preclinical findings.
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Affiliation(s)
- Raffaella Willmann
- Swiss Foundation for Research on Muscle Diseases, Cortaillod, Switzerland
| | - Annamaria De Luca
- Unit of Pharmacology, Department of Pharmacy and Drug Sciences, University of Bari "A. Moro," Bari, Italy
| | - Kanneboyina Nagaraju
- Center for Genetic Medicine Research, Children's National Medical Center, Washington, D.C., United States of America
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Willmann R, De Luca A, Benatar M, Grounds M, Dubach J, Raymackers JM, Nagaraju K. Enhancing translation: guidelines for standard pre-clinical experiments in mdx mice. Neuromuscul Disord 2011; 22:43-9. [PMID: 21737275 DOI: 10.1016/j.nmd.2011.04.012] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Revised: 04/05/2011] [Accepted: 04/27/2011] [Indexed: 11/26/2022]
Abstract
Duchenne Muscular Dystrophy is an X-linked disorder that affects boys and leads to muscle wasting and death due to cardiac involvement and respiratory complications. The cause is the absence of dystrophin, a large structural protein indispensable for muscle cell function and viability. The mdx mouse has become the standard animal model for pre-clinical evaluation of potential therapeutic treatments. Recent years have seen a rapid increase in the number of experimental compounds being evaluated in the mdx mouse. There is, however, much variability in the design of these pre-clinical experimental studies. This has made it difficult to interpret and compare published data from different laboratories and to evaluate the potential of a treatment for application to patients. The authors therefore propose the introduction of a standard study design for the mdx mouse model. Several aspects, including animal care, sampling times and choice of tissues, as well as recommended endpoints and methodologies are addressed and, for each aspect, a standard procedure is proposed. Testing of all new molecules/drugs using a widely accepted and agreed upon standard experimental protocol would greatly improve the power of pre-clinical experimentations and help identifying promising therapies for the translation into clinical trials for boys with Duchenne Muscular Dystrophy.
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Nagaraju K, Willmann R. Developing standard procedures for murine and canine efficacy studies of DMD therapeutics: report of two expert workshops on "Pre-clinical testing for Duchenne dystrophy": Washington DC, October 27th-28th 2007 and Zürich, June 30th-July 1st 2008. Neuromuscul Disord 2009; 19:502-6. [PMID: 19560356 DOI: 10.1016/j.nmd.2009.05.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2009] [Revised: 05/06/2009] [Accepted: 05/13/2009] [Indexed: 10/20/2022]
Affiliation(s)
- Kanneboyina Nagaraju
- Research Center for Genetic Medicine, Children's National Medical Center, Washington DC, USA
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Willmann R. Das Exoskelett der mannlichen Genitalien der Mecoptera (Insecta): II. Die phylogenetischen Beziehungen der Schnabelfliegen-Familien. J ZOOL SYST EVOL RES 2009. [DOI: 10.1111/j.1439-0469.1981.tb00237.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Willmann R. Über das Exoskelett von Austromerope poultoni Killington (Mecoptera: Meropeidae), ein Beitrag zur Phylogenie der Schnabelfliegen. J ZOOL SYST EVOL RES 2009. [DOI: 10.1111/j.1439-0469.1979.tb00713.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Willmann R, Possekel S, Dubach-Powell J, Meier T, Ruegg MA. Mammalian animal models for Duchenne muscular dystrophy. Neuromuscul Disord 2009; 19:241-9. [PMID: 19217290 DOI: 10.1016/j.nmd.2008.11.015] [Citation(s) in RCA: 140] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Revised: 11/24/2008] [Accepted: 11/27/2008] [Indexed: 11/27/2022]
Abstract
Duchenne muscular dystrophy (DMD) is a fatal neuromuscular disease that affects boys and leads to early death. In the quest for new treatments that improve the quality of life and in the search for a possible definitive cure, the use of animal models plays undoubtedly an important role. Therefore, a number of different mammalian models for DMD have been described. Much knowledge on the molecular mechanisms underlying the disease has arisen from studies in these animals. However, the use of different models does not often allow a direct comparison of results obtained in preclinical trials and therefore hinders a straightforward translational research. In the frame of "TREAT-NMD", a European Network of Excellence addressing the fragmentation in the assessment and treatment of neuromuscular diseases, we compare here the currently used mammalian animal models for DMD with the aim of selecting and recommending the most appropriate ones for preclinical efficacy testing of new therapeutic strategies.
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Affiliation(s)
- Raffaella Willmann
- Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland
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Willmann R, Rüegg M, Fairclough R, Davies K, Possekel S, Meier T. T.P.3.03 TREAT-NMD-Activity 7: Accelerate preclinical phase of new therapeutic treatment development. Neuromuscul Disord 2008. [DOI: 10.1016/j.nmd.2008.06.242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Willmann R, Pun S, Stallmach L, Sadasivam G, Santos AF, Caroni P, Fuhrer C. Cholesterol and lipid microdomains stabilize the postsynapse at the neuromuscular junction. EMBO J 2006; 25:4050-60. [PMID: 16932745 PMCID: PMC1560359 DOI: 10.1038/sj.emboj.7601288] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2006] [Accepted: 07/25/2006] [Indexed: 11/08/2022] Open
Abstract
Stabilization and maturation of synapses are important for development and function of the nervous system. Previous studies have implicated cholesterol-rich lipid microdomains in synapse stabilization, but the underlying mechanisms remain unclear. We found that cholesterol stabilizes clusters of synaptic acetylcholine receptors (AChRs) in denervated muscle in vivo and in nerve-muscle explants. In paralyzed muscles, cholesterol triggered maturation of nerve sprout-induced AChR clusters into pretzel shape. Cholesterol treatment also rescued a specific defect in AChR cluster stability in cultured src(-/-);fyn(-/-) myotubes. Postsynaptic proteins including AChRs, rapsyn, MuSK and Src-family kinases were strongly enriched in lipid microdomains prepared from wild-type myotubes. Microdomain disruption by cholesterol-sequestering methyl-beta-cyclodextrin disassembled AChR clusters and decreased AChR-rapsyn interaction and AChR phosphorylation. Amounts of microdomains and enrichment of postsynaptic proteins into microdomains were decreased in src(-/-);fyn(-/-) myotubes but rescued by cholesterol treatment. These data provide evidence that cholesterol-rich lipid microdomains and SFKs act in a dual mechanism in stabilizing the postsynapse: SFKs enhance microdomain-association of postsynaptic components, whereas microdomains provide the environment for SFKs to maintain interactions and phosphorylation of these components.
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Affiliation(s)
- Raffaella Willmann
- Department of Neurochemistry, Brain Research Institute, University of Zürich, Zürich, Switzerland
| | - San Pun
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Lena Stallmach
- Department of Neurochemistry, Brain Research Institute, University of Zürich, Zürich, Switzerland
| | - Gayathri Sadasivam
- Department of Neurochemistry, Brain Research Institute, University of Zürich, Zürich, Switzerland
| | | | - Pico Caroni
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Christian Fuhrer
- Department of Neurochemistry, Brain Research Institute, University of Zürich, Zürich, Switzerland
- Department of Neurochemistry, Brain Research Institute, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland. Tel.: +41 44 635 33 10; Fax: +41 44 635 33 03; E-mail:
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Sadasivam G, Willmann R, Lin S, Erb-Vögtli S, Kong XC, Rüegg MA, Fuhrer C. Src-family kinases stabilize the neuromuscular synapse in vivo via protein interactions, phosphorylation, and cytoskeletal linkage of acetylcholine receptors. J Neurosci 2006; 25:10479-93. [PMID: 16280586 PMCID: PMC6725837 DOI: 10.1523/jneurosci.2103-05.2005] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Postnatal stabilization and maturation of the postsynaptic membrane are important for development and function of the neuromuscular junction (NMJ), but the underlying mechanisms remain poorly characterized. We examined the role of Src-family kinases (SFKs) in vivo. Electroporation of kinase-inactive Src constructs into soleus muscles of adult mice caused NMJ disassembly: acetylcholine receptor (AChR)-rich areas became fragmented; the topology of nerve terminal, AChRs, and synaptic nuclei was disturbed; and occasionally nerves started to sprout. Electroporation of kinase-overactive Src produced similar but milder effects. We studied the mechanism of SFK action using cultured src(-/-);fyn(-/-) myotubes, focusing on clustering of postsynaptic proteins, their interaction with AChRs, and AChR phosphorylation. Rapsyn and the utrophin-glycoprotein complex were recruited normally into AChR-containing clusters by agrin in src(-/-);fyn(-/-) myotubes. But after agrin withdrawal, clusters of these proteins disappeared rapidly in parallel with AChRs, revealing that SFKs are of general importance in postsynaptic stability. At the same time, AChR interaction with rapsyn and dystrobrevin and AChR phosphorylation decreased after agrin withdrawal from mutant myotubes. Unexpectedly, levels of rapsyn protein were increased in src(-/-);fyn(-/-) myotubes, whereas rapsyn-cytoskeleton interactions were unaffected. The overall cytoskeletal link of AChRs was weak but still strengthened by agrin in mutant cells, consistent with the normal formation but decreased stability of AChR clusters. These data show that correctly balanced activity of SFKs is critical in maintaining adult NMJs in vivo. SFKs hold the postsynaptic apparatus together through stabilization of AChR-rapsyn interaction and AChR phosphorylation. In addition, SFKs control rapsyn levels and AChR-cytoskeletal linkage.
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Affiliation(s)
- Gayathri Sadasivam
- Department of Neurochemistry, Brain Research Institute, University of Zürich, CH-8057 Zürich, Switzerland
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Mittaud P, Camilleri AA, Willmann R, Erb-Vögtli S, Burden SJ, Fuhrer C. A single pulse of agrin triggers a pathway that acts to cluster acetylcholine receptors. Mol Cell Biol 2004; 24:7841-54. [PMID: 15340048 PMCID: PMC515067 DOI: 10.1128/mcb.24.18.7841-7854.2004] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Agrin triggers signaling mechanisms of high temporal and spatial specificity to achieve phosphorylation, clustering, and stabilization of postsynaptic acetylcholine receptors (AChRs). Agrin transiently activates the kinase MuSK; MuSK activation has largely vanished when AChR clusters appear. Thus, a tyrosine kinase cascade acts downstream from MuSK, as illustrated by the agrin-evoked long-lasting activation of Src family kinases (SFKs) and their requirement for AChR cluster stabilization. We have investigated this cascade and report that pharmacological inhibition of SFKs reduces early but not later agrin-induced phosphorylation of MuSK and AChRs, while inhibition of Abl kinases reduces late phosphorylation. Interestingly, SFK inhibition applied selectively during agrin-induced AChR cluster formation caused rapid cluster dispersal later upon agrin withdrawal. We also report that a single 5-min agrin pulse, followed by extensive washing, triggered long-lasting MuSK and AChR phosphorylation and efficient AChR clustering. Following the pulse, MuSK phosphorylation increased and, beyond a certain level, caused maximal clustering. These data reveal novel temporal aspects of tyrosine kinase action in agrin signaling. First, during AChR cluster formation, SFKs initiate early phosphorylation and an AChR stabilization program that acts much later. Second, a kinase mechanism rapidly activated by agrin acts thereafter autonomously in agrin's absence to further increase MuSK phosphorylation and cluster AChRs.
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Affiliation(s)
- Peggy Mittaud
- Brain Research Institute, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
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Moransard M, Borges LS, Willmann R, Marangi PA, Brenner HR, Ferns MJ, Fuhrer C. Agrin regulates rapsyn interaction with surface acetylcholine receptors, and this underlies cytoskeletal anchoring and clustering. J Biol Chem 2003; 278:7350-9. [PMID: 12486121 DOI: 10.1074/jbc.m210865200] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The acetylcholine receptor (AChR)-associated protein rapsyn is essential for neuromuscular synapse formation and clustering of AChRs, but its mode of action remains unclear. We have investigated whether agrin, a key nerve-derived synaptogenic factor, influences rapsyn-AChR interactions and how this affects clustering and cytoskeletal linkage of AChRs. By precipitating AChRs and probing for associated rapsyn, we found that in denervated diaphragm rapsyn associates with synaptic as well as with extrasynaptic AChRs showing that rapsyn interacts with unclustered AChRs in vivo. Interestingly, synaptic AChRs are associated with more rapsyn suggesting that clustering of AChRs may require increased interaction with rapsyn. In similar experiments in cultured myotubes, rapsyn interacted with intracellular AChRs and with unclustered AChRs at the cell surface, although surface interactions are much more prominent. Remarkably, agrin induces recruitment of additional rapsyn to surface AChRs and clustering of AChRs independently of the secretory pathway. This agrin-induced increase in rapsyn-AChR interaction strongly correlates with clustering, because staurosporine and herbimycin blocked both the increase and clustering. Conversely, laminin and calcium induced both increased rapsyn-AChR interaction and AChR clustering. Finally, time course experiments revealed that the agrin-induced increase occurs with AChRs that become cytoskeletally linked, and that this precedes receptor clustering. Thus, we propose that neural agrin controls postsynaptic aggregation of the AChR by enhancing rapsyn interaction with surface AChRs and inducing cytoskeletal anchoring and that this is an important precursor step for AChR clustering.
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Affiliation(s)
- Martijn Moransard
- Department of Neurochemistry, Brain Research Institute, University of Zürich, CH-8057 Zürich, Switzerland
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Abstract
Clustering of neurotransmitter receptors in the postsynaptic membrane is critical for efficient synaptic transmission. During neuromuscular synaptogenesis, clustering of acetylcholine receptors (AChRs) is an early sign of postsynaptic differentiation. Recent studies have revealed that the earliest AChR clusters can form in the muscle independent of motorneurons. Neurally released agrin, acting through the muscle-specific kinase MuSK and rapsyn, then causes further clustering and localization of clusters underneath the nerve terminal. AChRs themselves are required for agrin-induced clustering of several postsynaptic proteins, most notably rapsyn. Once formed, AChR clusters are stabilized by several tyrosine kinases and by components of the dystrophin/utrophin glycoprotein complex, some of which also direct postnatal synaptic maturation such as formation of postjunctional folds. This review summarizes these recent results about AChR clustering, which indicate that early clustering can occur in the absence of nerves, that AChRs play an active role in the clustering process and that partly different mechanisms direct formation versus stabilization of AChR clusters.
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Affiliation(s)
- R Willmann
- Department of Neurochemistry, Brain Research Institute, University of Zürich, Switzerland
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Willmann R, Kusch J, Sultan KR, Schneider AG, Pette D. Muscle LIM protein is upregulated in fast skeletal muscle during transition toward slower phenotypes. Am J Physiol Cell Physiol 2001; 280:C273-9. [PMID: 11208521 DOI: 10.1152/ajpcell.2001.280.2.c273] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Muscle LIM protein (MLP) is constitutively expressed in slow, but undetectable in fast, muscles of the rat. Here we show that MLP was upregulated at both the mRNA and protein levels under experimental conditions leading to transitions from fast to slower phenotypes. Chronic low-frequency stimulation and mechanical overloading by synergist removal both induced fast-to-slow shifts in myosin heavy chain (MHC) isoforms and expression of MLP in fast muscles. High amounts of MLP mRNA and protein were also present in fast muscles of the myotonic, hyperactive ADR mouse. Hypothyroidism evoked shifts in myosin composition toward slower isoforms and increased the MLP protein content of soleus (SOL) muscle but failed to induce MLP in fast muscles. Unweighting by hindlimb suspension elicited slow-to-fast transitions in MHC expression without altering MLP levels in SOL muscle. Hyperthyroidism shifted the MHC pattern toward faster isoforms but did not affect MLP content in SOL muscle. We conclude that alterations in MLP expression are associated with transitions from fast to slower phenotypes but not with slow-to-fast muscle fiber transitions.
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Affiliation(s)
- R Willmann
- Department of Biology, University of Konstanz, D-78457 Konstanz, Germany
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Abstract
Incubation of splenal lymphocytes with phorbol ester (50 nM PMA) influenced nuclear protein tyrosine phosphatase activity in a time-dependent manner. The activity was elevated after a short incubation (90 s) but was decreased in comparison to untreated cells after 30 and 120 min of incubation. The presence of H7 suppressed the changes. Okadaic acid, an inhibitor of protein phosphatases 2A and 1, led to a similar increase in the activity of nuclear protein tyrosine phosphatase during short-term incubations as phorbol ester but eliminated the subsequent activity decrease. Immunoblots revealed that the same amounts of two forms (49,000 and 60,000 M(r)) of protein tyrosine phosphatases were present in the nuclei from phorbol ester-stimulated and non-stimulated cells. The 60,000 M(r) form co-migrated with a phosphotyrosine-containing protein. The amount of phosphotyrosine was increased in comparison to control cells after 30 min of phorbol ester treatment.
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Affiliation(s)
- P Heimerl
- Faculty of Biology, University of Konstanz, Germany
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