title: Tubulin transport by IFT is upregulated during ciliary growth by a cilium-autonomous mechanism.
abstract: The assembly of the axoneme, the structural scaffold of cilia and flagella, requires translocation of a vast quantity of tubulin into the growing cilium, but the mechanisms that regulate the targeting, quantity, and timing of tubulin transport are largely unknown. In Chlamydomonas, GFP-tagged α-tubulin enters cilia as an intraflagellar transport (IFT) cargo and by diffusion. IFT-based transport of GFP-tubulin is elevated in growing cilia and IFT trains carry more tubulin. Cells possessing both nongrowing and growing cilia selectively target GFP-tubulin into the latter. The preferential delivery of tubulin boosts the concentration of soluble tubulin in the matrix of growing versus steady-state cilia. Cilia length mutants show abnormal kinetics of tubulin transport. We propose that cells regulate the extent of occupancy of IFT trains by tubulin cargoes. During ciliary growth, IFT concentrates soluble tubulin in cilia and thereby promotes elongation of the axonemal microtubules.
authors.affiliation: Department of Cellular Biology and College of Engineering, University of Georgia, Athens, GA 30602.
authors.forename: Julie M
authors.initials: JM
authors.lastname: Craft
authors.affiliation: Department of Cellular Biology and College of Engineering, University of Georgia, Athens, GA 30602.
authors.forename: J Aaron
authors.initials: JA
authors.lastname: Harris
authors.affiliation: Department of Cellular Biology and College of Engineering, University of Georgia, Athens, GA 30602.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Hyman
authors.affiliation: Department of Cellular Biology and College of Engineering, University of Georgia, Athens, GA 30602.
authors.forename: Peter
authors.initials: P
authors.lastname: Kner
authors.affiliation: Department of Cellular Biology and College of Engineering, University of Georgia, Athens, GA 30602 lechtrek@uga.edu.
authors.forename: Karl F
authors.initials: KF
authors.lastname: Lechtreck
mesh_terms: D016825:Chlamydomonas reinhardtii / Q000648:ultrastructure; D002923:Cilia / Q000502:physiology*; D004058:Diffusion; D005407:Flagella / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism*; D055503:Protein Multimerization; D021381:Protein Transport; D014404:Tubulin / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D010940:Plant Proteins; D014404:Tubulin