Glycosylation-independent lysosomal targeting of acid α-glucosidase enhances muscle glycogen clearance in pompe mice

J Biol Chem. 2013 Jan 18;288(3):1428-38. doi: 10.1074/jbc.M112.438663. Epub 2012 Nov 27.

Abstract

We have used a peptide-based targeting system to improve lysosomal delivery of acid α-glucosidase (GAA), the enzyme deficient in patients with Pompe disease. Human GAA was fused to the glycosylation-independent lysosomal targeting (GILT) tag, which contains a portion of insulin-like growth factor II, to create an active, chimeric enzyme with high affinity for the cation-independent mannose 6-phosphate receptor. GILT-tagged GAA was taken up by L6 myoblasts about 25-fold more efficiently than was recombinant human GAA (rhGAA). Once delivered to the lysosome, the mature form of GILT-tagged GAA was indistinguishable from rhGAA and persisted with a half-life indistinguishable from rhGAA. GILT-tagged GAA was significantly more effective than rhGAA in clearing glycogen from numerous skeletal muscle tissues in the Pompe mouse model. The GILT-tagged GAA enzyme may provide an improved enzyme replacement therapy for Pompe disease patients.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biological Transport / drug effects
  • Disease Models, Animal
  • Drug Delivery Systems / methods
  • Enzyme Replacement Therapy / methods*
  • Glucan 1,4-alpha-Glucosidase / genetics
  • Glucan 1,4-alpha-Glucosidase / metabolism*
  • Glycogen / metabolism*
  • Glycogen Storage Disease Type II / drug therapy*
  • Glycogen Storage Disease Type II / enzymology*
  • Glycogen Storage Disease Type II / genetics
  • Glycosylation
  • HEK293 Cells
  • Half-Life
  • Humans
  • Insulin-Like Growth Factor II / genetics
  • Insulin-Like Growth Factor II / metabolism
  • Kinetics
  • Lysosomes / drug effects*
  • Lysosomes / enzymology
  • Mice
  • Muscle, Skeletal / drug effects
  • Muscle, Skeletal / enzymology
  • Muscle, Skeletal / pathology
  • Mutant Chimeric Proteins / genetics
  • Mutant Chimeric Proteins / metabolism
  • Myoblasts / drug effects
  • Myoblasts / enzymology
  • Myoblasts / pathology
  • Plasmids
  • Receptor, IGF Type 2 / agonists
  • Receptor, IGF Type 2 / metabolism
  • Transfection

Substances

  • Mutant Chimeric Proteins
  • Receptor, IGF Type 2
  • Insulin-Like Growth Factor II
  • Glycogen
  • Glucan 1,4-alpha-Glucosidase