Abstract
Extract: Glycogen synthetase, phosphorylase, debrancher, and acid maltase activities were measured in fibroblasts from normal subjects and from five patients with three different forms of glycogen storage disease. Acid maltase was absent in fibroblasts from two patients with glycogenosis type II, debrancher activity was decreased in fibroblasts from two patients with glycogenosis type III, and phosphorylase activity was normal in fibroblasts from one patient with glycogenosis type V.
Fibroblasts from patients with glycogenosis types II and III accumulated more glycogen than normal cells; glycogen concentrations were about twice normal 10 days after subculture. In both types of mutant cells, glucose starvation was followed by rapid utilization of glycogen. Effective metabolism of glycogen in cells devoid of acid maltase activity makes the role of this enzyme uncertain.
Speculation: Glycogen is stored excessively in cultured skin fibroblasts from patients with glycogenosis types II (lack of acid maltase) and III (debrancher deficiency). The ready mobilization of glycogen in glycogenosis type II cells challenges the postulated lysosomal mechanism of this disease, or indicates that this in vitro system is not exactly comparable with the in vivo situation.
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Dimauro, S., Rowland, L. & Mellman, W. Glycogen Metabolism of Human Diploid Fibroblast Cells in Culture. I. Studies of Cells from Patients with Glycogenosis Types II, III, and V. Pediatr Res 7, 739–744 (1973). https://doi.org/10.1203/00006450-197309000-00002
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DOI: https://doi.org/10.1203/00006450-197309000-00002