The intraflagellar transport (IFT) machinery, containing the IFT-A and IFT-B complexes and powered by dynein-2 and kinesin-2 motors, is crucial for bidirectional trafficking of ciliary proteins and their import/export across the transition zone (TZ). Stepwise assembly of anterograde IFT trains was proposed previously; that is, the IFT-B complex first forms a TZ-tethered scaffold with sequential incorporation of IFT-A, dynein-2, and finally kinesin-2. However, IFT-A and IFT-B complexes also demonstrate distinct localization to the basal body/mother centriole. We show that IFT-A, IFT-B, and dynein-2 complexes are recruited to the mother centriole independently of ciliogenesis. Furthermore, mother centriole recruitment of IFT-A and IFT-B can occur in the absence of IFT-B and IFT-A, respectively, and dynein-2 recruitment is independent of IFT-A and IFT-B. Expansion microscopy revealed that the IFT-A/IFT-B pool at the basal body is distinct from that at the TZ. We conclude that IFT-A and IFT-B are recruited to the mother centriole in a mutually independent and ciliogenesis-independent manner before IFT train assembly.
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http://dx.doi.org/10.1091/mbc.E24-11-0509 | DOI Listing |
Mol Biol Cell
April 2025
Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan.
The intraflagellar transport (IFT) machinery, containing the IFT-A and IFT-B complexes and powered by dynein-2 and kinesin-2 motors, is crucial for bidirectional trafficking of ciliary proteins and their import/export across the transition zone (TZ). Stepwise assembly of anterograde IFT trains was proposed previously; that is, the IFT-B complex first forms a TZ-tethered scaffold with sequential incorporation of IFT-A, dynein-2, and finally kinesin-2. However, IFT-A and IFT-B complexes also demonstrate distinct localization to the basal body/mother centriole.
View Article and Find Full Text PDFNat Rev Mol Cell Biol
March 2025
Human Technopole, Milan, Italy.
J Adv Res
September 2024
Department of Psychiatry, National Clinical Research Center for Mental Disorders and National Center for Mental Disorders, The Second Xiangya Hospital, Central South University, Changsha 410011, China. Electronic address:
J Cell Sci
July 2024
MOE Key Laboratory of Protein Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China.
Intraflagellar transport (IFT) is required for ciliary assembly. The IFT machinery comprises the IFT motors kinesin-2 and IFT dynein plus IFT-A and IFT-B complexes, which assemble into IFT trains in cilia. To gain mechanistic understanding of IFT and ciliary assembly, here, we performed an absolute quantification of IFT machinery in Chlamydomonas reinhardtii cilium.
View Article and Find Full Text PDFBiomol NMR Assign
June 2024
RIKEN, Systems and Structural Biology Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, 230-0045, Japan.
The intraflagellar transport (IFT) machinery plays a crucial role in the bidirectional trafficking of components necessary for ciliary signaling, such as the Hedgehog, Wnt/PCR, and cAMP/PKA systems. Defects in some components of the IFT machinery cause dysfunction, leading to a wide range of human diseases and developmental disorders termed ciliopathies, such as nephronophthisis. The IFT machinery comprises three sub-complexes: BBsome, IFT-A, and IFT-B.
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