Pathogenesis of cystic renal disease

Several gene mutations cause renal cysts in humans, including PKD1 and PKD2 (autosomal dominant polycystic kidney disease, ADPKD), PKHD1 (autosomal recessive polycystic kidney disease, ARPKD), TSC1 and TSC2 (Tuberous Sclerosis), NPHP1 (Nephronophthisis type I), and VHL (von-Hippel-Lindau syndrome). This raises the question, whether there are common denominators of cyst development. Both polycystin-1 and fibrocystin, the gene products of PKD1 and PKHD1, appear to act as adhesion molecules. Polycystin-2, encoded by PKD2, is a ion channel that requires polycystin-1 to translocate to the plasma membrane. Polycystin-1 mandates TSC2 for the transport to the plasma membrane; thus, mutations of TSC2 could cause cyst formation by compromising the function of polycystin-1. Disturbences of fibrillary adhesion complexes may represent the final common pathway of NPHP1 as well as VHL mutations. Delineating common pathways of cystogenesis may help to design therapeutic strategies that combat the development and/or progression of renal cysts.