SUMOylation Regulates Super-Enhancers Through Transcription Factor TFAP2C Binding on Chromatin [ChIP-seq]. SUMOylation Regulates Super-Enhancers Through Transcription Factor TFAP2C Binding on Chromatin [ChIP-seq]

Genome wide localization of SUMO1 and SUMO2/3 proteins revealed an asscociation of SUMO proetins with active chromatin. SUMO proteins are enriched at super enhancers and enhancers and SUMOylation regulates a subset of these super enhancers. Super enhancers regulated by SUMOylation were enriched for transcription factor TFAP2C and SUMOylation negatively regulates TFAP2C localization to enhancers and super enhancers. Proteomics and ChIP-PCR at MYC SE suggests that chromatin bound TFAP2C recruits histone deacetylation complexes that increases upon SAE2 knockdown. Conversely, SUMOylation promoted TFAP2C asscociation with pre-mRNA splicing machinery components. Taken together, our study revealed a critical role of SUMOylation in chromatin modification through an AP-2 family of transcription factor, TFAP2C and a potential role of TFAP2C in pre-mRNA splicing. Overall design: Genomic distribution of SUMO 1 and SUMO2/3 proteins and their association with chromatin marks H3K72Ac, H4K4me3, H3K27me3 and coactivator Med1 were probed. Chages to super enhancer components H3K27Ac and Med1 were analysed upon SAE2 kd (absence of SUMOylation). Genomic distrubution of TFAP2C in control and SUMOylation depleted cells were measured.

对SUMO1与SUMO2/3蛋白开展全基因组定位分析，揭示了SUMO蛋白与活化染色质之间的关联。SUMO蛋白在超级增强子（super enhancer）与增强子（enhancer）区域富集，且SUMO化修饰（SUMOylation）可调控其中一部分超级增强子。受SUMO化修饰调控的超级增强子显著富集转录因子TFAP2C，且SUMO化修饰可负向调控TFAP2C向增强子与超级增强子的定位。在MYC超级增强子（MYC SE）处进行的蛋白质组学与染色质免疫沉淀-聚合酶链式反应（ChIP-PCR）实验显示，结合于染色质的TFAP2C可招募组蛋白去乙酰化复合物，且该招募过程在SAE2敲低后会增强。与之相反，SUMO化修饰可促进TFAP2C与前体mRNA剪接机器组分的结合。综上，本研究揭示了SUMO化修饰通过AP-2家族转录因子TFAP2C在染色质修饰中发挥关键作用，同时阐明了TFAP2C在前体mRNA剪接过程中的潜在功能。
实验设计概要：本研究检测了SUMO1与SUMO2/3蛋白的基因组分布特征，及其与染色质修饰标记H3K72Ac、H4K4me3、H3K27me3以及辅激活因子Med1之间的关联。针对SAE2敲低（即SUMO化修饰缺失）条件下，超级增强子相关组分H3K27Ac与Med1的变化情况开展了分析。同时检测了对照组与SUMO化修饰缺失细胞中TFAP2C的基因组分布情况。