Student Seminar on Sep 19, 2023



  Time 12:00-13:00,Sep 19, 2023
  Venue E203, Biomedicine Hall, Tsinghua University
  Speaker Shan Wang (王珊)
  Topic Molecular mechanisms of the polarity establishment in Drosophila mechanosensory cilia
  Abstract  The structure and molecular compositions determine the functional characteristics of a cilium. Although they are formed on conserved axonemal structure, they are diverse. For sensory cilia, modality-specific complexes are formed to detect distinct signals, such as light, chemical or force. Directional transport driven by molecular motors (e.g. the intraflagellar transport, IFT) plays a key role in specifying the molecular composition of these complexes. Here, we report a noncanonical intraciliary transport pathway mediated by Kif19A (a kinesin-8 family motor) that locates mechanosensory molecules to the tip domain of fly sensory cilia, where the kinesin-II motor is unexpectedly absent. Kif19A is identified in a RNA-Seq-based differential expression analysis targeting genes that express in ciliated sensory neurons. Kif19A is enriched at the ciliary tip. In the absence of Kif19A, the overall structure of the sensory cilia is fairly normal, but the mechanosensory molecules (e.g. NompC or DCX-MEAP) show aberrant localizations. In vitro analysis shows that Kif19A is a plus-end directed motor, shows a weak depolymerase activity and has a direct interaction with DCX-EMAP. Further in vivo analysis shows that the motility of Kif19A is not required for its ciliary entry but is indispensable for the optimal MO-specific localization of mechanosensory molecules, suggesting that Kif19A serves as a transporting motor that targets to the ciliary tip domain. In all, this study reveals the functional roles of Kif19A in the assembly of mechanosensory cilia, and provides novel molecular insights to understand how ciliary diversity can be established.