A shared temporal program for ventral spinal cord progenitors [CaTS-RNA]

The vertebrate neural tube generates a large diversity of molecularly and functionally distinct neurons and glia from a small progenitor pool. While the role of spatial patterning in organising cell fate specification has been extensively studied, temporal patterning, which controls the timing of cell type generation, is equally important. Here we define a global temporal programme in the spinal cord. This governs cell fate choices by regulating chromatin accessibility in neural progenitors. Perturbation of this cis-regulatory programme affects sequential transitions in spinal cord progenitors and the identity of progeny. The temporal programme operates in parallel to spatial patterning, ensuring the timely availability of regulatory elements for spatial determinants to direct cell-type specific gene expression. These findings identify a chronotopic spatiotemporal integration strategy in which a global temporal chromatin programme determines the output of a spatial gene regulatory network resulting in the temporally and spatially ordered allocation of cell type identity. Overall design: Mouse ES cell differentiation to spinal cord progenitors was sampled every two days from day 5 to day 11. Specific progenitors (p0-p1, p2 and pMN) were isolated and their chromatin accessibility or transcirption examined.