Adenylate cyclase regulates elongation of mammalian primary cilia

Exp Cell Res. 2009 Oct 1;315(16):2802-17. doi: 10.1016/j.yexcr.2009.06.028. Epub 2009 Jul 2.


The primary cilium is a non-motile microtubule-based structure that shares many similarities with the structures of flagella and motile cilia. It is well known that the length of flagella is under stringent control, but it is not known whether this is true for primary cilia. In this study, we found that the length of primary cilia in fibroblast-like synoviocytes, either in log phase culture or in quiescent state, was confined within a range. However, when lithium was added to the culture to a final concentration of 100 mM, primary cilia of synoviocytes grew beyond this range, elongating to a length that was on average approximately 3 times the length of untreated cilia. Lithium is a drug approved for treating bipolar disorder. We dissected the molecular targets of this drug, and observed that inhibition of adenylate cyclase III (ACIII) by specific inhibitors mimicked the effects of lithium on primary cilium elongation. Inhibition of GSK-3beta by four different inhibitors did not induce primary cilia elongation. ACIII was found in primary cilia of a variety of cell types, and lithium treatment of these cell types led to their cilium elongation. Further, we demonstrate that different cell types displayed distinct sensitivities to the lithium treatment. However, in all cases examined primary cilia elongated as a result of lithium treatment. In particular, two neuronal cell types, rat PC-12 adrenal medulla cells and human astrocytes, developed long primary cilia when lithium was used at or close to the therapeutic relevant concentration (1-2 mM). These results suggest that the length of primary cilia is controlled, at least in part, by the ACIII-cAMP signaling pathway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenylyl Cyclase Inhibitors
  • Adenylyl Cyclases / metabolism*
  • Animals
  • Astrocytes / cytology
  • Astrocytes / drug effects
  • Astrocytes / metabolism
  • Cells, Cultured
  • Cilia / drug effects
  • Cilia / metabolism*
  • Cilia / ultrastructure*
  • Cyclic AMP / metabolism
  • Enzyme Inhibitors / metabolism
  • Glycogen Synthase Kinase 3 / antagonists & inhibitors
  • Glycogen Synthase Kinase 3 / metabolism
  • Glycogen Synthase Kinase 3 beta
  • Humans
  • Lithium / pharmacology
  • Mice
  • NIH 3T3 Cells
  • PC12 Cells
  • Protein Kinase C / antagonists & inhibitors
  • Protein Kinase C / metabolism
  • Rats
  • Second Messenger Systems / physiology
  • Synovial Membrane / cytology
  • Synovial Membrane / drug effects


  • Adenylyl Cyclase Inhibitors
  • Enzyme Inhibitors
  • Lithium
  • Cyclic AMP
  • GSK3B protein, human
  • Glycogen Synthase Kinase 3 beta
  • Gsk3b protein, mouse
  • Gsk3b protein, rat
  • Protein Kinase C
  • Glycogen Synthase Kinase 3
  • Adenylyl Cyclases
  • adenylate cyclase 3