Embryonic stem cell based system for the discovery and mapping of developmental transcriptional programs

Chromatin immunoprecipitation followed by deep sequencing (ChIP-seq) is the method of choice to study function of transcription factors in cell fate determination. This technique faces two major obstacles when applied to developmental studies: the availability of ChIP grade antibodies and access to sufficient quantities of the cells of interest. We present a robust method for the genome-wide analysis of transcription factor binding during development in highly homogenous cells in defined developmental states. It combines efficient embryonic stem cell (ESC) differentiation protocols with an inducible system of tagged transcription factors to enable affinity based assays such as ChIP-seq during lineage specific development. To validate the system, we compared the activity and genomic binding of native and V5-tagged Olig2 in motor neuron progenitors and Flag-tagged and V5-tagged Hoxc9 in motor neurons. We find that tagging transcription factors and expressing them alongside their endogenous counterparts does not alter their function or genomic association. The technology presented here can be applied to known as well as novel DNA-binding proteins. In combination with a suitable ESC differentiation paradigm it can be applied to determine how lineage-specific transcriptional networks are established and regulated.