Juliette Azimzadeh (Institut Jacques Monod). Biophysics seminar ESPCI-ENS.

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27 January 2017 13:00 » 14:00 — ESPCI, Amphi Urbain, Ground Floor, Staircase N

Identification of Conserved Centriole Components Controlling Centriole Rotational Polarity in Multiciliated Cells

Multiciliated cells form hundreds of motile cilia that beat in a coordinated fashion to generate a fluid flow or displace particles and cells. To generate a directional fluid flow, cilia must beat in a specific orientation with respect to the plane of the epithelium. Beating orientation depends on the orientation within the plane of the plasma membrane of centrioles, from which cilia are assembled. Planarian flatworms, best known for their extraordinary regeneration capacity, use multiciliated cells for locomotion. Screening for genes affecting planarian locomotion, we identified specific centriole orientation factors connecting centriole structure to tissue polarity. Whereas wild type planarians move straight ahead, Smed-odf2(RNAi) flatworms move sideways to the right, and Smed-vfl1(RNAi) and Smed-vfl3(RNAi) move sideways to the left. We analysed centriole rotational polarity and found that, in control planarians, ciliary beat is aligned with the anterior-posterior axis in the region of the midline and progressively deviates from this axis toward the lateral edges. Thus, centriole rotational polarity varies along the medio-lateral axis to form a bilaterally symmetrical pattern of orientation. Following depletion of our candidate genes, abnormal direction of locomotion is correlated to defects in centriole rotational polarity. Our results suggest a model in which centriole orientation results from counterbalancing forces acting on the centrioles. The bilaterally symmetrical arrangement of centrioles across the ventral epidermis results from the complex regulation of cytoskeletal arrays that are intrinsically asymmetrical.

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