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Mannosidosis: deficiency of a specific alpha-mannosidase component in cultured fibroblasts
Abstract:
Evidence is prisented which shows that the enzymatic defect in mannosidosis, the deficiency of alpha-mannosidase, is expressed in cultured skin fibroblasts from patients with mannosidosis. Additionally, by Cellogel electrophoresis, the enzyme can be separated into two major components (a heat stable component missing in mannosidosis fibroblasts with a pH optimum of 3.6-4.0 and a heat labile component present in mannosidosis fibroblasts with a pH optimum of 5.6-6.0). The specific activity and electrophoresis of alpha-mannosidase from cultured amniotic fluid cells are also shown to be similar to cultured skin fibroblasts.
Insights
Mannosidosis is caused by a deficiency in alpha-mannosidase. This enzyme defect is detectable in cultured skin fibroblasts and amniotic fluid cells, aiding in diagnosis.
Area of Science:
- Biochemistry
- Medical Genetics
- Cell Biology
Background:
- Mannosidosis is a lysosomal storage disorder.
- The disease results from a deficiency of the enzyme alpha-mannosidase.
- This enzymatic defect leads to the accumulation of mannose-rich oligosaccharides.
Purpose of the Study:
- To investigate the expression of the enzymatic defect in mannosidosis.
- To characterize alpha-mannosidase in cultured cells.
- To assess the utility of cultured amniotic fluid cells for prenatal diagnosis.
Main Methods:
- Cultured skin fibroblasts from mannosidosis patients were used.
- Cellogel electrophoresis was employed to separate enzyme components.
- Enzyme activity and pH optima were analyzed.
Main Results:
- The deficiency of alpha-mannosidase was confirmed in cultured skin fibroblasts.
- Alpha-mannosidase separated into two components: heat-stable and heat-labile.
- Mannosidosis fibroblasts lacked the heat-stable component and showed altered activity of the heat-labile component.
- Cultured amniotic fluid cells exhibited similar enzyme characteristics to fibroblasts.
Conclusions:
- The enzymatic defect in mannosidosis is reliably expressed in cultured skin fibroblasts.
- Alpha-mannosidase exhibits distinct electrophoretic properties in normal and mannosidosis cells.
- Cultured amniotic fluid cells are suitable for prenatal diagnosis of mannosidosis.