A Modular Gain-of-Function Approach to Generate Cortical Interneuron Subtypes from ES Cells

•Known interneuron genes impacted cIN differentiation as expected•Novel transcription factors are systematically assayed using model system•Pou3f4 is identified as a factor that greatly improved differentiation efficiency•LMO3 biased to Pv cell fate; system predicted phenotype of null mouse

SummaryWhereas past work indicates that cortical interneurons (cINs) can be generically produced from stem cells, generating large numbers of specific subtypes of this population has remained elusive. This reflects an information gap in our understanding of the transcriptional programs required for different interneuron subtypes. Here, we have utilized the directed differentiation of stem cells into specific subpopulations of cortical interneurons as a means to identify some of these missing factors. To establish this approach, we utilized two factors known to be required for the generation of cINs, Nkx2-1 and Dlx2. As predicted, their regulated transient expression greatly improved the differentiation efficiency and specificity over baseline. We extended upon this “cIN-primed” model in order to establish a modular system whereby a third transcription factor could be systematically introduced. Using this approach, we identified Lmo3 and Pou3f4 as genes that can augment the differentiation and/or subtype specificity of cINs in vitro.