Regional differences in lectin binding pattern on the plasma membrane of dissociated rat bladder epithelial cells ad revealed by the ferritin-labeling method.

Abstract

The transitional epithelium of the rat urinary bladder was successfully dissociated to single cells and/or clumps of several attached cells, and the morphological features were well preserved in most of the cells. After tissue dissociation, therefore, three cell types, i. e., superficial, intermediate and basal cells, from the epithelium could be clearly and easily identified under the electron microscope. Ferritin-conjugated concanavalin A (Fer-ConA) and Ricinus communis agglutinin (Fer-RCA) binding sites on the surface of the dissociated cells were examined and compared by transmission electron microscopy.In the dissociated superficial cell, Fer-ConA binding sites were essentially negative on the apical plasma membrane except for on its ridge regions, while they were numerous and continuous on the basolateral plasma membrane. Thus, between the apical and the basolateral portions of the plasma membrane, there were obvious regional differences in ConA binding pattern as well as differences in morphological features. On the plasma membrane of the dissociated intermediate cell, Fer-ConA binding sites were distributed irregularly; and on the entire surface of the basal cell, they displayed an even and continuous distribution.In other words, the particular regions of the plasma membrane of the cell types that contained the asymmetric unit membrane lacked Fer-ConA, while the remaining regions with the ordinary unit membrane had numerous sites of Fer-ConA labeling. The basal cell showed the highest density of FerConA binding sites on the plasma membrane among all the cell types.Fer-RCA binding sites on the surface of the plasma membrane were numerous and continuous on the entire cell surface of all three epithelial cell types. In contrast to Fer-ConA, no differences were found in Fer-RCA binding pattern on the cell surfaces among three cell types except that the binding sites were somewhat more numerous in the basal cell.The apical plasma membrane of the superficial cell in the transitional epithelium of the rat urinary bladder is thus a specialized membrane in terms of morphology and composition of membrane surface carbohydrates. The cellular polarity of the superficial cell can be readily appreciated by the ferritin-labeled lectin binding technique.The transitional epithelium of the mammalian urinary bladder is composed of three cell layers, i. e., superficial, intermediate, and basal cell layers. The apical plasma membrane of the superficial cell is a highly specialized membrane with concave plaques of the asymmetric unit membrane (AUM), which have hexagonal lattice of sub-units and are separated by narrow ridge regions of the ordinary unit membrane (UM) (7). Ultrastructural features of the AUM are probably related to its functional properties, i. e., this membrane acts as a barrier to flow of water and ions between the hypertonic urine and the isotonic tissue fluids. It can be presumed that the ultrastructural and functional characteristics of the AUM reflect its unusual chemical composition of lipids and proteins...

Urinary System

“…Recent findings indicate a contributory role for immune effector cells to the pathology of glomerulonephritis through the production of cytokines after recruitment of such cells into the glomerulus (Vissers et al 1989;Tipping et al 1991a,b). In human lupus nephritis, serum IFN-ylevels and upregulated MHC class II expression, but not serum IL-2 receptor levels, were correlated to the occurrence of proliferative and active lesions (Yokoyama et al 1992). Kootstra et ai., manuscript in preparation).…”

“…271). They have been extensively characterized with respect to their ultrastructure (Hicks and Ketterer 1969;Hicks et al 1974), composition (Hicks et al 1974), enzyme histochemistry, and immunohistochemistry (Caruthers and Bonneville 1980a;Nishiyama et al 1992). On scanning electron micrographs (Figs.…”