PRC1 catalytic unit RING1B regulates early neural differentiation of human pluripotent stem cells
PRC1 catalytic unit RING1B regulates early neural differentiation of human pluripotent stem cells
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DOI：
10.1016/j.yexcr.2020.112294
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发表时间：
2020-11-01
影响因子：
3.7
通讯作者：
Pethe, Prasad
中科院分区：
文献类型：
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作者：
Desai, Divya;Khanna, Aparna;Pethe, Prasad
背景：Polycomb group （PcG）蛋白是一种组蛋白修饰因子，通过组装成称为Polycomb repression complex （PRC）的大型抑制复合物来控制基因表达；RING1B， PRC1的核心催化亚基，执行H2AK119单泛素化导致基因抑制。PRC1复合物在人类早期神经发育过程中的作用尚不清楚；我们试图用人类多能干细胞作为体外模型来揭示PRC1在神经元分化中的作用。结果：我们将人胚胎干细胞（hESCs）和人诱导多能干细胞（hiPSCs）向神经祖细胞阶段分化，从NESTIN、TUJ1、NCAD和PAX6的表达可见一斑。当我们检查RING1B和BMI1的总表达时，我们发现与未分化的细胞相比，它们在分化的神经祖细胞中显著上调。此外，我们使用染色质免疫沉淀结合qPCR来确定RING1B的定位，以及抑制组蛋白修饰H2AK119ub1在神经元特异性基因启动子上的定位。我们发现，RING1B在分化早期定位并催化TUJI、NCAM和NESTIN启动子上的H2AK119ub1修饰，随后RING1B从其启动子上丢失，导致它们的表达；而在神经祖细胞的成熟神经元基因如IRX3、GSX2、SOXI、NEURODI和FOXGI上，功能RING1B显著存在。结论：我们的研究结果表明，PRC1催化成分RING1B占据了人多能干细胞的神经元基因启动子，并可能阻止其早熟表达。然而，当给予神经元诱导信号时，RING1B不仅从神经元基因启动子中被移除，而且H2AK119ub1的抑制性修饰也丢失了。
Background: Polycomb group (PcG) proteins are histone modifiers which control gene expression by assembling into large repressive complexes termed - Polycomb repressive complex (PRC); RING1B, core catalytic subunit of PRC1 that performs H2AK119 monoubiquitination leading to gene repression. The role of PRC1 complex during early neural specification in humans is unclear; we have tried to uncover the role of PRC1 in neuronal differentiation using human pluripotent stem cells as an in vitro model.Results: We differentiated both human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs) towards neural progenitor stage evident from the expression of NESTIN, TUJ1, NCAD, and PAX6. When we checked the total expression of RING1B and BMI1, we saw that they were significantly upregulated in differentiated neural progenitors compared to undifferentiated cells. Further, we used Chromatin Immunoprecipitation coupled with qPCR to determine the localization of RING1B, and the repressive histone modification H2AK119ub1 at the promoters of neuronal specific genes. We observed that RING1B localized to and catalyzed H2AK119ub1 modification at promoters of TUJI, NCAM, and NESTIN during early differentiation and later RING1B was lost from its promoter leading their expression; while functional RING1B persisted significantly on mature neuronal genes such as IRX3, GSX2, SOXI, NEURODI and FOXGI in neural progenitors.Conclusion: The results of our study show that PRC1 catalytic component RING1B occupies neuronal gene promoters in human pluripotent stem cells and may prevent their precocious expression. However, when neuronal inductive signals are given, RING1B is not only removed from neuronal gene promoters, but the inhibitory H2AK119ub1 modification is also lost.