LYSOSOMAL CYSTEINE AND ASPARTIC PROTEINASES AND UBIQUITIN IN RAT AND HUMAN URINARY-BLADDER EPITHELIUM

To examine localization of cysteine and aspartic proteinases, and ubiq uitin in rat and human urinary bladders, immunocytochemistry was appli ed to the tissues, In semi-thin sections, immunoreactivity for catheps ins B and D was densely localized throughout epithelial layers of rats and humans, while that for cathepsins H and L was mainly localized in rat superficial and human intermediate cells, Immunoreactivity for ca thepsin C was relatively high in rat and human epithelia, especially i n humans, Immunoreactivity for ubiquitin was detected in rat and human epithelial cells. By electron microscopy, vesicular or heterogeneousl y dense lysosomes labeled with immunogold particles indicating catheps in B were seen in rat and human epithelial cells; particularly, they o ften appeared near fusiform vesicles in rat superficial cells and in h uman intermediate and superficial cells. By double immunostaining, lys osomes with or without vesicular structures were co-labeled with immun ogold particles showing both cathepsin B and ubiquitin, The results su ggest that cathepsins B, C, H, and L, and cathepsin D are involved in the lysosomal system of rat and human bladder epithelia, Moreover, con sidering that ubiquitin is a cofactor in the soluble ATP-dependent pro teolysis, the results may also indicate that epithelial cells actively form autophagolysosomes.