TGF-beta couples pluripotency and epithelial character via ZNF398

Human pluripotent stem cells (hPSCs) have the capacity to give rise to all differentiated cells of the adult. TGF-beta is used routinely for expansion of conventional hPSCs as flat epithelial colonies expressing the transcription factors POU5F1/OCT4, NANOG, SOX2. Here we report a global analysis of the transcriptional program controlled by TGF-beta followed by an unbiased gain-of-function screening in multiple hPSC lines to identify factors mediating TGF-beta activity. We identify a quartet of transcriptional regulators promoting hPSC self-renewal including ZNF398, a human-specific mediator of pluripotency and epithelial character in hPSCs. Mechanistically, ZNF398 binds active promoters and enhancers together with SMAD3 and the histone acetyltransferase EP300, enabling transcription of TGF-beta targets. In the context of somatic cell reprogramming, inhibition of ZNF398 abolishes activation of pluripotency and epithelial genes and iPSC colony formation. Our findings have clear implications for the generation of bona fide hPSCs for regenerative medicine. Stable transgenic hPSCs expressing candidates and SB43 treatment

人类多能干细胞（human pluripotent stem cells, hPSCs）具备分化为成体所有类型成熟细胞的潜能。转化生长因子-β（TGF-β）常规用于体外培养常规人类多能干细胞，使其维持为表达转录因子POU5F1/OCT4、NANOG与SOX2的扁平上皮样集落。本研究对TGF-β调控的转录程序进行了全局分析，并在多株人类多能干细胞中开展无偏倚功能获得性筛选，以鉴定介导TGF-β信号活性的调控因子。我们鉴定出可促进人类多能干细胞自我更新的四重转录调控因子，其中包括锌指蛋白398（ZNF398）——一种人类特异性的多能性维持与上皮特性调控因子。机制层面，ZNF398与SMAD3及组蛋白乙酰转移酶EP300结合于活性启动子与增强子区域，从而介导TGF-β靶基因的转录激活。在体细胞重编程实验体系中，抑制ZNF398会阻断多能性与上皮相关基因的激活，并完全抑制诱导多能干细胞集落的形成。本研究结果对于制备可用于再生医学的纯正人类多能干细胞具有明确的指导意义。过表达候选调控因子的稳定转基因人类多能干细胞及SB43处理