Epithelial Planar Bipolarity Emerges from Notch-Mediated Asymmetric Inhibition of Emx2.

摘要: Summary Most plane-polarized tissues are formed by identically oriented cells [ 1 , 2 ]. A notable exception occurs in the vertebrate vestibular system and lateral-line neuromasts, where mechanosensory hair orient along a single axis but opposite directions to generate bipolar epithelia 3 4 5 In zebrafish pairs of arise from division non-sensory progenitor 6 7 ] acquire opposing planar polarity via asymmetric expression polarity-determinant transcription factor Emx2 8 9 10 11 Here, we reveal initial symmetry-breaking step decrypting developmental trajectory using single-cell RNA sequencing (scRNA-seq), diffusion pseudotime analysis, lineage tracing, mutagenesis. We show that is absent epithelial cells, begins hair-cell progenitors, downregulated one sibling signaling through Notch1a receptor. Analysis Emx2-deficient specimens, which every cell adopts an identical direction, indicates asymmetry does not result auto-regulatory feedback. These data two-tiered mechanism symmetric monodirectional ground state epithelium inverted deterministic initiation progenitors subsequent stochastic repression breaks directional symmetry establish bipolarity.