Abstract
In microvillous atrophy PAS positive secretory granules accumulate in the apical cytoplasm of intestinal epithelium and brush border (BB) PAS staining is reduced. This suggests that protein transport to the BB may be disrupted in the disease. We have studied SI localisation and metabolism in order to investigate this hypothesis using organ culture, radio-iodination with immunoprecipitation, immunocytochemistry, and immunogold EM. Disaccharidase activities were decreased in the cases. Immunoperoxidase (n=6) and immuno EM (n=3) demonstrated SI antigen in the BB apical membrane and not in the secretory granules. Radioiodination and immunoprecipitation (n=3) showed initial transport to, and processing in, the Golgi complex to be normal; no cleaved subunits could be detected, although proenzyme did not accumulate. Organ culture (n=1) showed normal synthesis and processing of SI. Thus SI synthesis and transport appear to be normal in microvillous atrophy and the nature of the secretory granules is elusive, but may hold the key to this disease. A second exocytotic pathway may exist in man which is associated with intractable diarrhoea when disrupted.
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Phillips, A., Fransen, J., Hauri, HP. et al. SUCRASE-ISOMALTASE (SI) LOCALISATION AND BIOGENESIS IS NORMAL IN MICROVILLOUS ATROPHY. Pediatr Res 27, 533 (1990). https://doi.org/10.1203/00006450-199005000-00045
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DOI: https://doi.org/10.1203/00006450-199005000-00045
