ADULT, FETAL, AND POLYCYSTIC KIDNEY EXPRESSION OF POLYCYSTIN, THE POLYCYSTIC KIDNEY DISEASE-1 GENE-PRODUCT

The polycystic kidney disease-1 gene, which is mutated in the majority of patients with autosomal dominant polycystic kidney disease, has be en identified. The protein encoded by this gene, polycystin, has no ho mology with any gene known thus far. To gain more insight into the fun ction of polycystin, we raised antibodies against synthetic peptides a nd a fusion protein corresponding to the sequence of two different fra gments of polycystin. Two of the antibodies were capable of immunoprec ipitating an in vitro transcription and translation product correspond ing to a fragment of polycystin. In the cyst-lining epithelium of poly cystic kidney disease-1 patients, a strong staining was observed. In n ormal adult and embryonic kidney tissues, expression was seen in the e pithelium of all tubular structures and in the glomerular parietal and visceral epithelium (podocytes), although the podocytes were mainly r ecognized on cryosections and not on paraffin sections. A double-label ed immunofluorescence with one of the polycystin antibodies and the mo noclonal antibody 8G8 ascertained that within the glomerular tuft podo cytes were recognized.