Drug induced exocytosis of glycogen in Pompe disease.
Pompe disease is caused by a deficiency in the lysosomal enzyme α-glucosidase, and this leads to glycogen accumulation in the autolysosomes of patient cells. Glycogen storage material is exocytosed at a basal rate in cultured Pompe cells, with one study showing up to 80% is released under specific culture conditions. Critically, exocytosis induction may reduce glycogen storage in Pompe patients, providing the basis for a therapeutic strategy whereby stored glycogen is redirected to an extracellular location and subsequently degraded by circulating amylases. The focus of the current study was to identify compounds capable of inducing rapid glycogen exocytosis in cultured Pompe cells. Here, calcimycin, lysophosphatidylcholine and α-l-iduronidase each significantly increased glycogen exocytosis compared to vehicle-treated controls. The most effective compound, calcimycin, induced exocytosis through a Ca2+-dependent mechanism, although was unable to release a pool of vesicular glycogen larger than the calcimycin-induced exocytic pore. There was reduced glycogen release from Pompe compared to unaffected cells, primarily due to increased granule size in Pompe cells. Drug induced exocytosis therefore shows promise as a therapeutic approach for Pompe patients but strategies are required to enhance the release of large molecular weight glycogen granules.
Regenerative Medicine, Future Industries Institute, University of South Australia, Adelaide, Australia.
Christopher T
CT
Turner
Genetics and Molecular Pathology, SA Pathology, Adelaide, Australia.
Maria
M
Fuller
Lysosomal Diseases Research Unit, SA Health and Medical Research Institute, Adelaide, Australia.
John J
JJ
Hopwood
Baker IDI Heart and Diabetes Institute, Melbourne, Australia.
Peter J
PJ
Meikle
Mechanisms in Cell Biology and Diseases Research Group, School of Pharmacy and Medical Science, Division of Health Sciences, University of South Australia, Adelaide 5001, Australia. Electronic address: Doug.Brooks@unisa.edu.au.
Doug A
DA
Brooks
D000001:Calcimycin / Q000494:pharmacology* / Q000627:therapeutic use; D002478:Cells, Cultured; D004353:Drug Evaluation, Preclinical; D005089:Exocytosis / Q000187:drug effects*; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D006003:Glycogen / Q000378:metabolism*; D006009:Glycogen Storage Disease Type II / Q000188:drug therapy / Q000378:metabolism*; D006801:Humans; D007068:Iduronidase / Q000494:pharmacology* / Q000627:therapeutic use; D008244:Lysophosphatidylcholines / Q000494:pharmacology* / Q000627:therapeutic use; D008247:Lysosomes / Q000187:drug effects; D010588:Phagosomes / Q000187:drug effects; D014677:Pharmaceutical Vehicles / Q000494:pharmacology
D008244:Lysophosphatidylcholines; D014677:Pharmaceutical Vehicles; D000001:Calcimycin; D006003:Glycogen; D007068:Iduronidase
Exocytosis; Glycogen; Lysosomal storage disorder; Pompe disease