Regulatory networks specifying cortical interneurons from human embryonic stem cells reveal roles for CHD2 in interneuron development

Human embryonic stem cells (hESCs) were specified as ventral telencephalic neuroectoderm (day 4) and then into medial ganglionic emininence (MGE)-like progenitors (day 15) and were subsequently differentiated into cortical interneuron (cIN)-like cells (day 25-35), by modification of previously published protocols. RNA-seq analysis at days 0, 4, 15, 25, and 35 defined transcriptome signatures for MGE and cIN cell identity. Further integration of these gene expression signatures with ChIP-seq for the NKX2-1 transcription factor in MGE-like progenitors defined NKX2-1 putative direct targets, including genes involved in both MGE specification and in several aspects of later cIN differentiation (migration, synaptic function). Among the NKX2-1 direct targets with MGE and cIN enriched expression was CHD2, a chromatin remodeling protein. Since CHD2 haploinsufficiency can cause epilepsy and/or autism, which can involve altered cIN development or function, we evaluated CHD2 requirements in these processes. Transcriptome changes were evaluated in CHD2 knockdown MGE-like progenitors at day 15, revealing diminished expression of genes involved in MGE specification and cIN differentiation including channel and synaptic genes implicated in epilepsy, while later cIN electrophysiological properties were also altered. We defined some shared cis-regulatory elements bound by both NKX2-1 and CHD2 and characterized their ability to cooperatively regulate cIN gene transcription through these elements. We used these data to construct regulatory networks underlying MGE specification and cIN differentiation and to define requirements for CHD2 and its ability to cofunction with NKX2-1 in this process.