SOX1 Determines the Regional Identity of Neural Progenitors Differentiated from Human Embryonic Stem Cells

During human embryogenesis, primitive neural cells start to be generated at the time of gastrulation and gradually acquire regional identities, which is a process called neural patterning. But how intrinsic factors respond to exogenous patterning signals remains poorly understood. Human Embryonic Stem Cells (hESCs) provide a great model to recapitulate this process. Through exogenous manipulation of canonical WNT signaling activation during neural differentiation, dose-dependent specification of regionally defined neural progenitors ranging from the telencephalic forebrain to posterior hindbrain could be rapidly and efficiently induced. Unexpectedly, we find that SOX1, generally referred as a pan-neural gene, displays a regional specific distribution in the human neural patterning process. To investigate the expression and function of SOX1 efficiently, we have generated the SOX1-EGFP reporter and SOX1-knockout (KO) hESC lines using the CRISPR/Cas9 system. SOX1 is initially expressed across the mes–met border and peaked in the metencephalon region at the early regional specification stage. Its depletion leads to the posterior shift of the mes–met border. Therefore, SOX1 is required to define the border at a correct region. In-depth analysis of SOX1 ChIP-sequencing and transcriptome data will provide more insights into how SOX1 determines the mes-met border formation and identify the downstream targets of SOX1. This study identifies SOX1 as one of the intrinsic factors key for the prepattern establishment in the developing central nervous system, particularly for defining the isthmus position. To analysis the function of SOX1 in early neural differentiation, we compared the gene expression profiles between wild type and SOX1-/- cells at 3 time points (Day 0, 4, 8) during neural differentiation by mRNA sequencing.