Glomerular Podocytes Express Protocadherin 17

During a search for cadherin-related molecules expressed in rat glomeruli by RT-PCR with degenerate primers, we have isolated cDNA encoding protocadherin 17 (Pcdh17) in addition to Fat1. Although Pcdh17 has been suggested to participate in cell-cell adhesion and cell sorting, little is known about its distribution and function. To elucidate the localization and expression of Pcdh17, ribonuclease protection assay and in situ hybridization were performed in the rat. Pcdh17 expression was detected distinctly in RNAs from the cerebrum, cerebellum, lung, but spleen but weakly in RNAs from the whole kidney. In the kidney, intense signals for Pcdh17 were found in glomerular RNAs, with only or weak signals at best in cortical and medullary RNAs. In situ hybridization showed that Pcdh17 was predominantly expressed by podocytes in the glomerulus. Pcdh17 were found to have two isoforms that differ in the length of the cytoplasmic domains. The expression level of both isoforms did not change in puromycin aminonucleoside nephrosis where slit diaphragms disappear and new junctional complexes are newly formed. In conclusion, Pcdh17 is expressed by podocytes, which may be involved in several types of their intercellular junctions.