AJP - Cell Physiology, Vol 253, Issue 3 C433-C443, Copyright © 1987 by American Physiological Society

ARTICLES

A distal nephron glycoprotein that has different cell surface distributions on MDCK cell sublines

G. K. Ojakian, R. E. Romain and R. E. Herz

Monoclonal antibodies that recognize three distinct epitopes of a 23-kDa glycoprotein (gp23) on the plasma membrane of MDCK cells were used to study cell-surface polarity. Immunofluorescence microscopy of MDCK cells obtained from the American Type Culture Collection demonstrated that gp23 was nonpolarized in approximately 50% of the cells (on both apical and basolateral membranes), whereas, in the remaining cells, gp23 had a polarized distribution (basolateral only). This heterogeneous gp23 cell-surface staining was not observed in a variety of other MDCK sublines. Instead, gp23 was found to have a nonpolarized distribution on MDCK cells that produced monolayers with low transepithelial electrical resistances (less than 220 omega X cm2) and was localized only to the basolateral membrane of MDCK cell lines capable of generating considerably higher transepithelial electrical resistances (770-2,220 omega X cm2). Immunofluorescence and immunoelectron microscopy of dog, rat, and rabbit kidney demonstrated that gp23 is a nephron segment-specific glycoprotein localized only to the distal and collecting tubules. These observations provide further evidence for the heterogeneity of the MDCK cell line. They also support a proposal that the origin of MDCK cells is the renal distal nephron.

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