Because hMGEOs and hCOs exhibited striking parallels to the developing human MGE and cortex, we next sought to identify key regulators involved in lineage specification. We constructed a co-expression network of transcriptional and epigenetic regulators. The network showed two dense and several smaller subnetworks (Figure 5J). The densest subnetwork (green) included transcription factors expressed in NPCs (e.g. HMGB2) and represented the network of basal transcriptional factors (Figure S4F). Cortical neuronal markers (NEUROD6 and CTIP2) were detected in the second densest subnetwork (red), whereas interneuron markers (NKX2-1 and DLX6) were in a small subnetwork (olivegreen). Cut homeobox family transcription factor, ONECUT1, whose function in MGE development has not been fully explored, was directly connected to NKX2-1 and DLX6 in the network and uniquely expressed in interneurons (Figure S4F). Another interneuron marker, LHX1, was a hub factor connecting the interneuron subnetwork with others. We also found that functionally-unknown transcription factors were enriched in high metabolic intermediate progenitors (BNIP3 and DDIT3) and in subplate cells (EPAS1 and NR4A1). Overall, our results demonstrate that hMGEOs and hCOs recapitulate lineage productions in the developing human MGE and cortical domains, and provide a resource to dissect cell identities and key regulators for human brain development.
