Knock-in mice for the R50X mutation in the PYGM gene present with McArdle disease

Knock-in mice for the R50X mutation in the PYGM gene present with McArdle disease

1. Gisela Nogales-Gadea¹,²,³,*,


2. Tomàs Pinós¹,³,*,


3. Alejandro Lucia⁴,


4. Joaquín Arenas³,⁵,


5. Yolanda Camara¹,³,


6. Astrid Brull¹,³,


7. Noemí de Luna¹,³,


8. Miguel A. Martín³,⁵,


9. Elena Garcia-Arumí¹,³,


10. Ramon Martí¹,³,* and


11. Antoni L. Andreu¹,³,*

+ Author Affiliations

1. 
   1 Laboratori de Patologia Mitocondrial i Neuromuscular, Hospital Universitari Vall d’Hebron, Institut de Recerca (VHIR), Universitat Autònoma de Barcelona, 08035 Barcelona, Spain
   
   


2. 
   2 Laboratory of Neuromuscular diseases, Institut de Recerca Hospital de la Santa Creu i Sant Pau-IIB Sant Pau, Universitat Autònoma de Barcelona, 08025 Barcelona, Spain
   
   


3. 
   3 Centre for Biomedical Network Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Spain
   
   


4. 
   4 Department of Physiology, Universidad Europea de Madrid, 28670 Villaviciosa de Odón, Madrid, Spain
   
   


5. 
   5 Centro de Investigación, Hospital Universitario 12 de Octubre, 28041 Madrid, Spain
   
   

1. Correspondence to: Antoni L. Andreu, MD, Ph.D, Institut de Recerca Hospital Universitari Vall d’Hebron, Barcelona, Spain, E-mail: toniandreu.bcn@gmail.com

• Received March 6, 2012.


• Revision received April 5, 2012.


• Accepted April 22, 2012.

Summary

McArdle disease (glycogenosis type V), the most common muscle glycogenosis, is a recessive disorder caused by mutations in PYGM, the gene encoding myophosphorylase. Patients with McArdle disease typically experience exercise intolerance manifested as acute crises of early fatigue and contractures, sometimes with rhabdomyolysis and myoblobinuria, triggered by static muscle contractions or dynamic exercises. Currently, there are no therapies to restore myophosphorylase activity in patients. Although two spontaneous animal models for McArdle disease have been identified (cattle and sheep), they have rendered a limited amount of information on the pathophysiology of the disorder; therefore, there have been few opportunities for experimental research in the field. We have developed a knock-in mouse model by replacing the wild-type allele of Pygm with a modified allele carrying the common human mutation, p.R50X, which is the most frequent cause of McArdle disease. Histochemical, biochemical and molecular analyses of the phenotype, as well as exercise tests, were carried out in homozygotes, carriers and wild-type mice. p.R50X/p.R50X mice showed undetectable myophosphorylase protein and activity in skeletal muscle. Histochemical and biochemical analyses revealed massive muscle glycogen accumulation in homozygotes, in contrast to heterozygotes or wild-type mice, which did not show glycogen accumulation in this tissue. Additional characterization confirmed a McArdle disease-like phenotype in p.R50X/p.R50X mice, i.e. they had hyperCKaemia and very poor exercise performance, as assessed in the wire grip and treadmill tests (6% and 5% of the wild-type values, respectively). This model represents a powerful tool for in-depth studies of the pathophysiology of McArdle disease and other neuromuscular disorders, and for exploring new therapeutic approaches for genetic disorders caused by premature stop codon mutations.

Key words

• McArdle disease


• knock-in mouse


• p.R50X mutation


• glycogenosis type V


• neuromuscular disorders