Phosphatidylinositol transfer protein/planar cell polarity axis regulates neocortical morphogenesis by supporting interkinetic nuclear migration

The neocortex expands explosively during embryonic development. The earliest populations of neural stem cells (NSCs) form a thin pseudostratified epithelium whose contour determines that of the adult neocortex. Neocortical complexity is accompanied by disproportional expansion of the NSC layer in its tangential dimension to increase tissue surface area. How such disproportional expansion is controlled remains unknown. We demonstrate that a phosphatidylinositol transfer protein (PITP)/non-canonical Wnt planar cell polarity (ncPCP) signaling axis promotes tangential expansion of developing neocortex. PITP signaling supports trafficking of specific ncPCP receptors from the NSC Golgi system to potentiate actomyosin activity important for cell-cycle-dependent interkinetic nuclear migration (IKNM). In turn, IKNM promotes lateral dispersion of newborn NSCs and tangential growth of the cerebral wall. These findings clarify functional roles for IKNM in NSC biology and identify tissue dysmorphogenesis resulting from impaired IKNM as a factor in autism risk, developmental brain disabilities, and neural tube birth defects.

Automated summary

During embryonic development, the neocortex undergoes explosive expansion, with disproportionate growth in the neural stem cell layer. A signaling axis involving phosphatidylinositol transfer protein (PITP) and non-canonical Wnt planar cell polarity (ncPCP) promotes tangential expansion of the neocortex. This expansion is crucial for the development of the cerebral wall and has implications for neurodevelopmental disorders.