Induced Cdx2 binding in progenitor motor neurons and its effect on H3K27me3 chromatin domains [Affymetrix]

We aim to understand the role that Cdx2 plays in specifying the rostro-caudal identity of differentiating motor neurons. We find that expressing Cdx2 in combination with FGF signaling is sufficient to produce motor neurons with a more caudal identity. ChIP-seq analysis of Cdx2 finds that it binds extensively throughout the Hox regions in progenitor motor neurons. Analysis of polycomb-associated chromatin over Hox regions in the subsequently generated motor neurons finds that Cdx2 binding corresponds to chromatin domains encompassing de-repressed caudal Hox genes. These results suggest a direct role for Cdx2 in specifying caudal motor neuron identity. Expression studies: Affymetrix arrays are used to profile gene expression in ES cells, RA/Hh-derived Day 5 motor neurons, and RA/Hh-derived motor neurons that have also been exposed to Dox (to activate iCdx2) and FGF.