Shear stress-dependent regulation of apical endocytosis in renal proximal tubule cells mediated by primary cilia

Significance The proximal tubule (PT) of the kidney is the primary site for reabsorption of ions, solutes, and filtered low molecular weight proteins. PT cells rapidly modulate ion transport capacity in response to the fluid shear stress (FSS) that accompanies changes in glomerular filtration rate. We report here that PT cells also adjust their capacity for endocytosis in response to FSS. Apical endocytosis of the megalin–cubilin ligand albumin and of fluid phase markers is markedly increased upon exposure to FSS. Moreover, Ca2+ signaling mediated by the primary cilia on PT cells is required for this response. These studies define a novel pathway in PT cells that plays an essential role in maintaining kidney function.