Cholesterol ensures ciliary polycystin-2 localization to prevent polycystic kidney disease

The plasma membrane covering the primary cilium has a diverse accumulation of receptors and channels. To ensure the sensor function of the cilia, the ciliary membrane has higher cholesterol content than other cell membrane regions. A peroxisomal biogenesis disorder, Zellweger syndrome, characterized by polycystic kidney, is associated with a reduced level of ciliary cholesterol in cells. However, the etiological mechanism by which ciliary cholesterol lowering causes polycystic kidney disease remains unclear. Here, we demonstrated that lowering ciliary cholesterol by either pharmacological treatment or genetic depletion of peroxisomes impairs the localization of a ciliary ion channel polycystin-2. We also generated cultured renal medullary cells and mice carrying a missense variant in the cholesterol-binding site of polycystin-2 detected in the patient database of autosomal dominant polycystic kidney disease. This missense protein showed normal channel activity but decreased localization to the ciliary membrane. The homozygous mice exhibited embryonic lethality and the ciliopathy spectrum conditions of situs inversus and polycystic kidney. Our results suggest that cholesterol controls the ciliary localization of polycystin-2 to prevent polycystic kidney disease.