斯隆-凯特林癌症中心的Danwei Huangfu课题组与约翰霍普金斯大学的Michael A. Beer课题组合作揭示JNK-JUN信号通路在多能干细胞分化过程中扮演的角色。 相关论文发表在2019年6月出版的《Nature Genetics》杂志上。

首先，研究人员进行了全基因组CRISPR筛选参与胚胎干细胞往定型内胚层（definitive endoderm，DE）分化过程中的调控因子，并意外地发现了五个JNK-JUN家族的基因涉及抑制DE分化。JNK-JUN通路并不直接通过抑制负责DE分化的增强子来发挥功能。相反，JUN与OCT4、NANOG、SMAD2和SMAD3这些转录因子共同定位于胚胎干细胞的增强子处，进而通过阻碍胚胎干细胞增强子的失活以及抑制SMAD2和SMAD3从胚胎干细胞增强子处转移到DE增强子处来实现对多潜能干细胞分化的抑制。因此，JUK-JUN通路可维持多潜能性以免过早的DE分化。使用JNK的小分子抑制剂能够提升胚胎干细胞向DE分化以及形成DE来源的胰腺和肺前体细胞的效率。这项研究表明利用发育生物学的知识进行再生医学研究拥有巨大潜力。

据悉，人类胚胎干细胞和诱导性多能干细胞为细胞治疗与药物发现带来新的曙光。但如何让这些干细胞均质分化是实现其应用道路上的一个重大挑战，因此解析这背后的发育机制有助于解决这一问题。

Title: Genome-scale screens identify JNK–JUN signaling as a barrier for pluripotency exit and endoderm differentiation

Author: Qing V. Li, Gary Dixon, Nipun Verma, Bess P. Rosen, Miriam Gordillo, Renhe Luo, Chunlong Xu, Qiong Wang, Chew-Li Soh, Dapeng Yang, Miguel Crespo, Abhijit Shukla, Qing Xiang, Friederike Dndar, Paul Zumbo, Matthew Witkin, Richard Koche, Doron Betel, Shuibing Chen, Joan Massagu, Ralph Garippa, Todd Evans, Michael A. Beer, Danwei Huangfu

Issue&Volume:Volume 51 Issue 6, June 2019

Abstract: Human embryonic stem cells (ESCs) and human induced pluripotent stem cells hold great promise for cell-based therapies and drug discovery. However, homogeneous differentiation remains a major challenge, highlighting the need for understanding developmental mechanisms. We performed genome-scale CRISPR screens to uncover regulators of definitive endoderm (DE) differentiation, which unexpectedly uncovered five Jun N-terminal kinase (JNK)JUN family genes as key barriers of DE differentiation. The JNKJUN pathway does not act through directly inhibiting the DE enhancers. Instead, JUN co-occupies ESC enhancers with OCT4, NANOG, SMAD2 and SMAD3, and specifically inhibits the exit from the pluripotent state by impeding the decommissioning of ESC enhancers and inhibiting the reconfiguration of SMAD2 and SMAD3 chromatin binding from ESC to DE enhancers. Therefore, the JNKJUN pathway safeguards pluripotency from precocious DE differentiation. Direct pharmacological inhibition of JNK significantly improves the efficiencies of generating DE and DE-derived pancreatic and lung progenitor cells, highlighting the potential of harnessing the knowledge from developmental studies for regenerative medicine.

DOI: 10.1038/s41588-019-0408-9

Source:https://www.nature.com/articles/s41588-019-0408-9