Human Molecular Genetics Advance Access published online on September 9, 2008
Human Molecular Genetics, doi:10.1093/hmg/ddn290
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Modulation of glycogen synthesis by RNA interference: towards a new therapeutic approach for glycogenosis type II
1 Institut Cochin, Université Paris Descartes, CNRS (UMR 8104), Paris, France 2 Inserm, U567, Paris, France 3 Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA
# Corresponding author: Dr Catherine Caillaud, Institut Cochin, Département Génétique et Développement, 24 rue du Faubourg St Jacques, 75014 Paris, France. Phone: +33 1 44 41 24 02, Fax: +33 1 44 41 24 46. E-mail: catherine.caillaud{at}inserm.fr
Received July 21, 2008; Revised September 8, 2008; Accepted September 8, 2008
Glycogen storage disease type II (GSDII) or Pompe disease is an autosomal recessive disorder caused by defects in the acid alpha-glucosidase (GAA) gene, which leads to lysosomal glycogen accumulation and enlargement of the lysosomes mainly in cardiac and muscle tissues, resulting in fatal hypertrophic cardiomyopathy and respiratory failure in the most severely affected patients. Enzyme replacement therapy has already proven to be beneficial in this disease, but correction of pathology in skeletal muscle still remains a challenge. As substrate deprivation was successfully used to improve the phenotype in other lysosomal storage disorders, we explore here a novel therapeutic approach for GSDII based on a modulation of muscle glycogen synthesis. ShRNAs targeted to the two major enzymes involved in glycogen synthesis, i.e. glycogenin (shGYG) and glycogen synthase (shGYS), were selected. C2C12 cells and primary myoblasts from GSDII mice were stably transduced with lentiviral vectors expressing both the shRNAs and the EGFP reporter gene. Efficient and specific inhibition of glycogenin and glycogen synthase was associated not only with a decrease in cytoplasmic and lysosomal glycogen accumulation in transduced cells, but also with a strong reduction of the lysosomal size, as demonstrated by confocal microscopy analysis. A single intramuscular injection of recombinant AAV-1 vectors expressing shGYS into newborn GSDII mice led to a significant reduction of glycogen accumulation, demonstrating the in vivo therapeutic efficiency. These data offer new perspectives for the treatment of GSDII and could be relevant to other muscle glycogenoses.
* Present address: INSERM U876, IFR 66, Université Bordeaux 2, 146 rue Léo Saignat, 33076 Bordeaux, E-mail: emmanuel.richard{at}u-bordeaux2.fr