Stem cell-based approach to identify regulatory TFs during mammalian cell differentiation.

Cell differentiation is regulated by transcription factors (TFs), but specific TFs needed for mammalian differentiation pathways are not fully understood. For example, during spinal motor neuron (MN) differentiation, 1,370 TFs are transcribed, yet only 55 have reported functional relevance. We developed a method combining pluripotent stem cell differentiation, single-cell transcriptomics, and a CRISPR-based TF loss-of-function screen and applied it to MN differentiation. The CRISPR screen identified 245 genes important for mouse MN differentiation, including 116 TFs. This screen uncovered important genes not showing differential transcription and identified a regulatory hub at the MN progenitor (pMN) stage. A secondary human screen of 69 selected candidates revealed a conservation between mouse pMN and human pMN and ventral pMN (vpMN) regulations. The validation of three hits required for efficient human MN differentiation supported the effectiveness of our approach. Collectively, our strategy offers a framework for identifying important TFs in various differentiation pathways.