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Intraflagellar transport: it's not just for cilia anymore

Cosima T Baldari1, Joel Rosenbaum

  • 1Department of Molecular, Cellular and Developmental Biology, 310 Kline Biology Tower, PO Box 208103, Yale University, New Haven, CT 06520-8103, United States. Baldari@unisi.it

Current Opinion in Cell Biology
|December 8, 2009
PubMed

Insights

Intraflagellar transport (IFT) moves polypeptides into cilia via vesicles, suggesting cilia function as secretory organelles. This process is key for immune synapse formation in nonciliated cells.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Immunology

Background:

  • Intraflagellar transport (IFT) is essential for ciliary assembly and function.
  • Vesicle exocytosis plays a critical role in cellular communication and signaling.
  • The immune synapse is a crucial structure for T cell activation and function.

Purpose of the Study:

  • To review recent findings on the role of IFT polypeptides in vesicle exocytosis.
  • To propose a hypothesis for the mechanism of polypeptide entry into cilia.
  • To explore the potential secretory function of cilia.

Main Methods:

  • Literature review of published research on IFT, vesicle exocytosis, and cilia.
  • Analysis of the formation of the immune synapse in nonciliated cells as a model system.
  • Hypothetical model development for polypeptide transport and secretion via cilia.

Main Results:

  • IFT polypeptides are involved in vesicle exocytosis, particularly in immune synapse formation.
  • A hypothesis suggests polypeptides enter cilia via cytoplasmic vesicles that exocytose near the basal body.
  • Proteins are transported to the ciliary tip by IFT along the ciliary membrane.
  • At the tip, polypeptides are released for axonemal assembly or budded off as exosomes.

Conclusions:

  • Cilia may function not only as sensory and motile organelles but also as secretory organelles.
  • The proposed mechanism highlights a novel pathway for protein transport and secretion involving cilia.
  • Understanding this pathway could have implications for various cellular processes and diseases.

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