Moss-Derived Human Recombinant GAA Provides an Optimized Enzyme Uptake in Differentiated Human Muscle Cells of Pompe Disease

Int J Mol Sci. 2020 Apr 10;21(7):2642. doi: 10.3390/ijms21072642.


Pompe disease is an autosomal recessive lysosomal storage disorder (LSD) caused by deficiency of lysosomal acid alpha-glucosidase (GAA). The result of the GAA deficiency is a ubiquitous lysosomal and non-lysosomal accumulation of glycogen. The most affected tissues are heart, skeletal muscle, liver, and the nervous system. Replacement therapy with the currently approved enzyme relies on M6P-mediated endocytosis. However, therapeutic outcomes still leave room for improvement, especially with regard to skeletal muscles. We tested the uptake, activity, and effect on glucose metabolism of a non-phosphorylated recombinant human GAA produced in moss (moss-GAA). Three variants of moss-GAA differing in glycosylation pattern have been analyzed: two with terminal mannose residues in a paucimannosidic (Man3) or high-mannose (Man 5) configuration and one with terminal N-acetylglucosamine residues (GnGn). Compared to alglucosidase alfa the moss-GAA GnGn variant showed increased uptake in differentiated myotubes. Moreover, incubation of immortalized muscle cells of Gaa-/- mice with moss-GAA GnGn led to similarly efficient clearance of accumulated glycogen as with alglucosidase alfa. These initial data suggest that M6P-residues might not always be necessary for the cellular uptake in enzyme replacement therapy (ERT) and indicate the potential of moss-GAA GnGn as novel alternative drug for targeting skeletal muscle in Pompe patients.

Keywords: Pompe disease; enzyme replacement therapy; glycogen storage disease type II; moss-GAA.

MeSH terms

  • Animals
  • Biomarkers
  • Bryophyta / genetics
  • Cells, Cultured
  • Energy Metabolism / drug effects
  • Enzyme Replacement Therapy* / methods
  • Glycogen Storage Disease Type II / drug therapy
  • Glycogen Storage Disease Type II / etiology
  • Glycogen Storage Disease Type II / metabolism*
  • Humans
  • Mice
  • Muscle Cells / drug effects*
  • Muscle Cells / metabolism*
  • Myoblasts / drug effects
  • Myoblasts / metabolism
  • Recombinant Proteins / pharmacology*
  • Recombinant Proteins / therapeutic use
  • alpha-Glucosidases / pharmacology
  • alpha-Glucosidases / therapeutic use


  • Biomarkers
  • Recombinant Proteins
  • GAA protein, human
  • alpha-Glucosidases