The renal cell primary cilium functions as a flow sensor

Curr Opin Nephrol Hypertens. 2003 Sep;12(5):517-20. doi: 10.1097/00041552-200309000-00006.


Purpose of review: To discuss recent reports on the function and importance of the renal primary cilium, a widely distributed organelle.

Recent findings: Most epithelial cells, including those in the kidney, express a solitary primary cilium. The primary cilium functions as a flow sensor in cultured renal epithelial cells (MDCK and mouse collecting tubule) mediating a large increase in intracellular calcium concentration. Flow sensing is shown to reside in the cilium itself and to involve the proteins polycystin 1 and 2, defects in which are associated with the majority of cases of human polycystic kidney disease. The role of the cilium in flow-dependent potassium secretion by the collecting tubule and in sensing of chemical components of the luminal fluid are also described.

Summary: The primary cilium is mechanically sensitive and serves as a flow sensor in cultured renal epithelia. Bending the cilium by mechanical means or flow causes a large, prolonged transient increase in intracellular calcium. The mechanically sensitive protein in the cilium is a polycystin.

Publication types

  • Review

MeSH terms

  • Animals
  • Calcium Channels / metabolism
  • Calcium-Binding Proteins / metabolism
  • Cells, Cultured
  • Cilia / physiology
  • Epithelial Cells / metabolism
  • Epithelial Cells / physiology*
  • Epithelial Cells / ultrastructure*
  • Humans
  • Kidney / metabolism
  • Kidney / physiology*
  • Kidney / ultrastructure*
  • Membrane Proteins / metabolism
  • Proteins / metabolism
  • TRPP Cation Channels


  • Calcium Channels
  • Calcium-Binding Proteins
  • Membrane Proteins
  • Proteins
  • TRPP Cation Channels
  • polycystic kidney disease 1 protein
  • polycystic kidney disease 2 protein