Abstract
ABSTRACT: Cultured fibroblasts from mucolipidosis II (ML-II) patients demonstrated an elevated cystine content which increased with time in culture compared to fibroblasts from cystinotic patients or normal controls under the same conditions. In both cystinotic and ML-II cells the increased levels of cystine could be derived either from endogenous proteolysis or from in vitro supplementation of the cultured cells with cysteine-glutathione mixed disulfide. Cystine was depleted from both cell types by cysteamine. When cysteamine was replaced with complete medium, the cystine reaccumulated in both cystinotic and ML-II cells within 24 h, although a lag of 4 h was seen with ML-II cells. The intracellular location of the increased cystine in cultured fibroblasts was examined utilizing free-flow electrophoresis and found to be in the purified population of secondary lysosomes of both cystinotic and ML-II cells. White blood cell and hepatic cystine, which was greatly increased in cystinotic patients, was not elevated in ML-II patients. Compared to normal control fibroblasts the efflux of cystine from isolated granular fractions was virtually absent in cystinotic fibroblasts and considerably reduced in ML-II fibroblasts. The examination of such similarities and differences in cystine accumulation and transport in tissues from cystinotic and ML-II patients has provided some insight into the defects in these diseases.
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Greene, A., Jonas, A., Harms, E. et al. Lysosomal Cystine Storage in Cystinosis and Mucolipidosis Type II. Pediatr Res 19, 1170–1174 (1985). https://doi.org/10.1203/00006450-198511000-00011
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DOI: https://doi.org/10.1203/00006450-198511000-00011
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