Hypoxia regulates assembly of cilia in suppressors of Tetrahymena lacking an intraflagellar transport subunit gene

Mol Biol Cell. 2003 Aug;14(8):3192-207. doi: 10.1091/mbc.e03-03-0166. Epub 2003 May 3.


We cloned a Tetrahymena thermophila gene, IFT52, encoding a homolog of the Chlamydomonas intraflagellar transport protein, IFT52. Disruption of IFT52 led to loss of cilia and incomplete cytokinesis, a phenotype indistinguishable from that of mutants lacking kinesin-II, a known ciliary assembly transporter. The cytokinesis failures seem to result from lack of cell movement rather than from direct involvement of ciliary assembly pathway components in cytokinesis. Spontaneous partial suppressors of the IFT52 null mutants occurred, which assembled cilia at high cell density and resorbed cilia at low cell density. The stimulating effect of high cell density on cilia formation is based on the creation of pericellular hypoxia. Thus, at least under certain conditions, ciliary assembly is affected by an extracellular signal and the Ift52p function may be integrated into signaling pathways that regulate ciliogenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Algal Proteins / metabolism*
  • Amino Acid Sequence
  • Animals
  • Cell Count
  • Cell Division*
  • Cell Hypoxia / physiology*
  • Cilia / metabolism*
  • Cilia / ultrastructure
  • Kinesins / metabolism
  • Microscopy, Electron
  • Molecular Sequence Data
  • Mutation
  • Protozoan Proteins / metabolism*
  • Sequence Homology
  • Tetrahymena thermophila / cytology*
  • Tetrahymena thermophila / genetics


  • Algal Proteins
  • Protozoan Proteins
  • Kinesins