title: Chemical chaperones improve transport and enhance stability of mutant alpha-glucosidases in glycogen storage disease type II.
abstract: Glycogen storage disease type II (GSDII; Pompe disease or acid maltase deficiency) is an autosomal recessive disorder caused by lysosomal acid alpha-glucosidase (AalphaGlu) deficiency and manifests predominantly as skeletal muscle weakness. Defects in post-translational modification and transport of mutant AalphaGlu species are frequently encountered and may potentially be corrected with chaperone-mediated therapy. In the present study, we have tested this hypothesis by using deoxynojirimycin and derivatives as chemical chaperones to correct the AalphaGlu deficiency in cultured fibroblasts from patients with GSDII. Four mutant phenotypes were chosen: Y455F/Y455F, P545L/P545L, 525del/R600C and D645E/R854X. In case of Y455F/Y455F and P545L/P545L, N-(n-butyl)deoxynojirimycin (NB-DNJ) restored the transport, maturation and activity of AalphaGlu in a dose dependent manner, while it had no effect on the reference enzyme beta-hexosaminidase. NB-DNJ promoted export from the endoplasmic reticulum (ER) to the lysosomes and stabilized the activity of mutant AalphaGlu species, Y455F and P545L, inside the lysosomes. In long-term culture, the AalphaGlu activity in the fibroblasts from the patients with mutant phenotypes, Y455F/Y455F and P545L/P545L, increased up to 14.0- and 7.9-fold, respectively, in the presence of 10mumol/L NB-DNJ. However, the effect of NB-DNJ on Y455F/Y455F subsided quickly after removal of the compound. We conclude that NB-DNJ acts in low concentration as chemical chaperone for certain mutant forms of AalphaGlu that are trapped in the ER, poorly transported or labile in the lysosomal environment. Chemical chaperone therapy could create new perspectives for therapeutic intervention in GSDII.
authors.affiliation: Department of Clinical Genetics, Erasmus MC, PO Box 2040, 3000 CA Rotterdam, The Netherlands. okumiyat@hs.kumamoto-u.ac.jp
authors.forename: Toshika
authors.initials: T
authors.lastname: Okumiya
authors.forename: Marian A
authors.initials: MA
authors.lastname: Kroos
authors.forename: Laura Van
authors.initials: LV
authors.lastname: Vliet
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Takeuchi
authors.forename: Ans T
authors.initials: AT
authors.lastname: Van der Ploeg
authors.forename: Arnold J J
authors.initials: AJ
authors.lastname: Reuser
mesh_terms: D017485:1-Deoxynojirimycin / Q000494:pharmacology; D000293:Adolescent; D000328:Adult; D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D019556:COS Cells; D002478:Cells, Cultured; D002675:Child, Preschool; D002522:Chlorocebus aethiops; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004795:Enzyme Stability / Q000187:drug effects / Q000502:physiology; D006009:Glycogen Storage Disease Type II / Q000201:enzymology* / Q000235:genetics; D065089:Glycoside Hydrolase Inhibitors; D006801:Humans; D007223:Infant; D018832:Molecular Chaperones / Q000008:administration & dosage* / Q000502:physiology; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology; D017384:Sequence Deletion; D000520:alpha-Glucosidases / Q000235:genetics / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D065089:Glycoside Hydrolase Inhibitors; D018832:Molecular Chaperones; D017485:1-Deoxynojirimycin; D000520:alpha-Glucosidases