Expression of polycystins and fibrocystin on primary cilia of lung cells

Mutations in polycystin-1, polycystin-2, or fibrocystin account for autosomal dominant or recessive polycystic kidney disease. Renal cystogenesis is linked to abnormal localization and function of these cystoproteins in renal primary cilia. They are also expressed in extrarenal tissues in which their functions are unclear. Here we found that human type-II alveolar epithelial A549, airway submucosal Calu-3 cells, and rat bronchioles contain primary or multiple cilia in which we detected these cystoproteins. At sub-confluency, polycystin-1 was expressed on plasma membrane, while polycystin-2 was localized to the ER of resting cells. Both polycystins were detected on the spindle and mid-body of mitotic cells, while fibrocystin was on centrosome throughout cell cycle. Polycystins and fibrocystin may participate in regulating mucociliary sensing and transport within pulmonary airways.