Rootletin Fiber Dynamics Integrate Cytoskeletal Programs to Shape Neuroepithelial Architecture

Abstract

Central nervous system (CNS) architecture is established early by the organization and proliferative behavior of neuroepithelial (NE) cells, which form a pseudostratified epithelium during neural tube (NT) formation. In neurogenesis, newborn neurons have to detach and exit the neuroepithelium, in a process that requires the coordinated disassembly of apical junctions and the centrosome-cilia module. Although Rootletin--the structural component of the ciliary rootlet and centriolar linker--is classically viewed as a static mechanical element, its behavior in NE cells has not been described in detail. Here, we uncover a conserved, dynamic form of Rootletin fiber organization that remodels in synchrony with NE cell morphogenesis. We show that, in NE cells in interphase, Rootletin fibers extend from the basal body through the apical process toward the nucleus, and that Rootletin maintains its fibrous conformation throughout mitosis. As NE cells initiate apical constriction, Rootletin fibers retract from the apical process and assemble into an anisotropic rim-like structure that aligns with the apical junctional complex. This remodeling is coordinated with microtubule stabilization in low-tension apical endfeet and occurs prior to Lzts1 expression and increased actomyosin contractility. Forced neuronal delamination via Neurogenin-2 or Lzts1 promotes Rootletin rim formation and Rootletin alignment with the apical endfoot cortex. Finally, we show that Zika virus NS5 protein can aberrantly associate with all conformational states of Rootletin fibers, providing a potential mechanical link between ZikaV infection and premature delamination. Together, our findings identify Rootletin as a dynamically regulated cytoskeletal scaffold that orchestrates apical surface remodeling in NE cells and identify a potential mechanism by which ZikaV disrupts neurodevelopment.