Altered synthesis of proteoglycans by cyst-derived cells from autosomal-dominant polycystic kidneys

Normal human renal epithelial cells (NK) and cells from cysts of autosomal-dominant polycystic kidneys (ADPKD) were radiolabeled with [35S]sulfate. A two- to three-fold decrease in the radioactivity incorporated into the proteoglycan (PG) fraction, as ascertained by tissue autoradiography and biochemical techniques, was observed in the ADPKD group. In subconfluent NK cells, PGs eluted as two peaks with different proportions of chondroitin sulfate (CS) and heparan sulfate (HS) in the cellular and media fractions. In the confluent stage, only a single major peak in the media and matrix fractions was seen and had variable proportions of CS and HS. In subconfluent ADPKD monolayers, cellular PGs eluted as two peaks, with the major peak of higher molecular weight compared with NK cells. In confluent stage, there was a single PG peak of a relatively higher molecular weight, with a variable increase in the proportions of CS vs. HS and lower charge-density characteristics. These findings indicate that size and species of PGs vary during subconfluent and confluent stages of culture and elucidate a defect in the biosynthesis of PGs in human ADPKD cells.