Two distinct signaling pathways, involving Wnt signaling and polycystin, have been found to
be critical for normal kidney development. Renal tubulogenesis requires the presence of
certain Wnt proteins, whereas mutations in polycystin impede the terminal differentiation of
renal tubular epithelial cells, causing the development of large cystic kidneys that
characterize autosomal dominant polycystic kidney disease. Polycystin is an integral
membrane protein, consisting of several extracellular motifs indicative of cell-cell and cell …