| 研究実績の概要 |
Epithelial folding is typically driven by localized acto-myosin contractility. It remains unclear, however, how epithelia deform when myosin levels are low and uniform. In the Drosophila gastrula, dorsal fold formation occurs despite lack of localized myosin changes, while the fold-initiating cells reduce cell height upon basal shifts of polarity via an unknown mechanism. Work performed during the past years under auspice of this grant showed that cell shortening depends on an apical microtubule network organized by the CAMSAP protein Patronin. Prior to gastrulation, microtubule forces generated by the minus-end motor dynein scaffold the apical cell cortex into a dome-like shape, while the severing enzyme Katanin facilitates network remodeling to ensure tissue-wide cell size homeostasis. During fold initiation, Patronin redistributes upon basal polarity shifts in the initiating cells, apparently weakening the scaffolding forces to allow dome descent.
The homeostatic network that ensures size/shape homogeneity is thus repurposed for cell shortening, linking epithelial polarity to folding via a microtubule-based mechanical mechanism. Our data implicates for the first time a cell shape control function for the CAMSAP family proteins. Furthermore, the mechanical model for dome apical formation and remodeling, akin to the forces that the ribs exert on the canopy of an opened umbrella, ushers in a new concept for Dynein-mediated, microtubule-based mechanics. Our paper that describes this work has been recently published at Nature Cell Biology (Takeda et al. 2018).
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