Rational cell fate engineering through chromatin dynamics [CUT&TAG]

Mechanism controlling cell fate remains elusive. Chromatin remodeling complex interacts with transcription factors to colocalize across the genome and regulate region-specific epigenetic environment. Here, we propose an engineering approach for controlling cell fate through chromatin closing and opening. We utilize chromatin remodeling complex, BAF, known to activate gene expression by opening chromatin loci. By grafting BAF interacting motifs onto Nanog, we show that engineering factors could promote somatic cell reprogramming with Oct4. Furthermore, mutation on the interacting motifs render iPSC generation. The syntactic factors facilitate cell fate transition by recruiting BAF complex to modulate chromatin accessibility and reorganize cell state specific enhancers. Our findings reveal alternative methods to control cell fate by manipulating chromatin accessibility. CUT&Tag analysis was performed in reprogramming intermediates of day 5 to map Nanog, Smarca4, H3K27ac and H3K4me binding sites.

调控细胞命运的具体机制至今仍不甚明晰。染色质重塑复合物（Chromatin Remodeling Complex）可与转录因子（Transcription Factors）相互作用，在全基因组范围内共定位，并调控区域特异性的表观遗传微环境。本研究提出一种通过染色质开闭调控细胞命运的工程化策略。我们采用了已知可通过开放染色质位点激活基因表达的染色质重塑复合物BAF。通过将BAF相互作用基序移植至Nanog中，我们证实该工程化因子可联合Oct4促进体细胞重编程。此外，对该相互作用基序引入突变可影响诱导多能干细胞（induced Pluripotent Stem Cells, iPSC）的生成。此类工程化因子可通过招募BAF复合物以调控染色质可及性，并重塑细胞状态特异性的增强子，从而促进细胞命运转换。本研究结果揭示了一种通过操控染色质可及性调控细胞命运的替代方法。本研究于重编程第5天的中间细胞中开展CUT&Tag分析，以绘制Nanog、Smarca4、H3K27ac及H3K4me的结合位点图谱。