Protein gene product 9.5 is selectively localized in parietal epithelial cells of Bowmen's capsule in the rat kidney

Parietal epithelial cells (PEC) of Bowman's capsules cover the inner aspect of Bowman's capsules and are believed to contribute to extracapillary lesi ons of glomerulonephritis such as crescent formation. In glomerular researc h including cell culture experiments and pathology, differentiation between PEC and podocytes has frequently been a major problem. Immunohistochemistr y of the adult rat kidney for protein gene product 9.5 (PGP 9.5), a neuron- specific ubiquitin C-terminal hydrolase, demonstrated selective localizatio n of the immunoreactivity in PEG. At the urinary pole of the glomerulus, im munoreactive PEC were clearly differentiated from proximal tubular cells th at were negative for PGP 9.5. In the subcapsular nephrogenic zone of newbor n rat kidney, immunoreactivity was observed in almost all cells in the comm a-shaped body and early S-shaped body and selectively in PEC in the late S- shaped body and capillary-stage glomerulus. In rat glomerular disease model s (Masugi-nephritis and puromycin aminonucleoside nephrosis), cells that co nsisted of cellular crescents or adhered to glomerular tufts were positive for PGP 9.5. The selective localization of PGP 9.5 in PEC in rat kidney pro vides a new cytochemical marker for identifying the cells. Developmental ex pression of the protein suggests that PGP 9.5 is involved in the processes of nephrogenesis of rat kidney.