Direct Conversion of Mouse Fibroblasts into Neural Stem Cells by Chemical Cocktail Requires Stepwise Activation of Growth Factors and Nup210

Neural stem cells (NSCs) are valuable for both basic research and clinical application. We previously reported a chemical cocktail that could reprogram somatic cells into neural progenitor cells. However, the process of chemical induction is complex and the underlying mechanism remains largely elusive. Here, we identified a new culture condition that greatly promotes the efficiency of NSC generation directly from mouse fibroblasts based on our reported chemical cocktail. Transcriptome and epigenome analyses during the reprogramming process demonstrated that growth factors including IL6, FGF5 and LIF were dynamically activated and contributed to the chemical cocktail induced cell fate changes. Interestingly, fibroblast-to-NSC conversion requires the synergistic action of these growth factors. Moreover, the reprogramming capacity of both chemical cocktail and growth factors require nucleoporin Nup210 to activate endogenous neural transcription factors SoxB1 family to initiate NSC fate. Our study not only provides a novel protocol to generate NSC directly from mouse fibroblasts, but also reveals an important role of growth factors in chemical-induced cellular reprogramming. Overall design: mRNA profile and epigenetic analysis of fibroblasts treated chemical cocktail at different timepoints

神经干细胞（Neural stem cells，NSCs）在基础研究与临床应用中均具有重要价值。本团队此前曾报道过一种可将体细胞重编程为神经前体细胞的化学组合配方。然而，该化学诱导过程较为复杂，其潜在的分子机制仍未完全阐明。本研究基于此前报道的化学组合配方，开发了一种全新的培养体系，可显著提升直接从小鼠成纤维细胞制备神经干细胞的效率。重编程过程中的转录组与表观基因组分析显示，IL6、FGF5及LIF等生长因子呈现动态激活特征，并参与了化学组合配方诱导的细胞命运转变。值得注意的是，成纤维细胞向神经干细胞的转化依赖于上述生长因子的协同作用。此外，化学组合配方与生长因子的重编程能力均需核孔蛋白Nup210介导，通过激活内源性神经转录因子SoxB1家族以启动神经干细胞命运程序。本研究不仅为直接从小鼠成纤维细胞制备神经干细胞提供了全新的实验方案，同时揭示了生长因子在化学诱导细胞重编程中的关键作用。实验设计：对经不同时间点化学组合配方处理的成纤维细胞进行mRNA表达谱及表观基因组分析