Cell non-autonomy amplifies disruption of neurulation by mosaic Vangl2 deletion

Post-zygotic mutations that generate tissue mosaicism are increasingly associated with severe congenital defects, including those arising from failed neural tube closure. We observed that elevation of the neural folds during mouse spinal neurulation is vulnerable to deletion of the planar cell polarity core component Van Gogh-like (Vangl)2 in as few as 16% of neuroepithelial cells. Vangl2-deleted cells are typically dispersed throughout the neuroepithelium, and each non-autonomously prevents apical constriction by an average of five Vangl2-replete neighbours. This inhibition of apical constriction involves reduced myosin-II recruitment to neighbour cell borders and shortening of basally-extending microtubule tails, which are known to facilitate apical constriction. Vangl2-deleted cells themselves continue to apically constrict and preferentially recruit myosin-II to their apical cell cortex rather than to apical cap sarcomere-like organisations. Such non-autonomous effects can explain how post-zygotic mutations affecting a minority of cells can cause catastrophic failure of morphogenesis leading to clinically important birth defects.