PDF(Pubmed)
Abstract：
Catalytic activity of the imitation switch (ISWI) family of remodelers is critical for nucleosomal organization and DNA binding of certain transcription factors, including the insulator protein CTCF. Here we define the contribution of individual subcomplexes by deriving a panel of isogenic mouse stem cell lines, each lacking one of six ISWI accessory subunits. Individual deletions of subunits of either CERF, RSF, ACF, WICH or NoRC subcomplexes only moderately affect the chromatin landscape, while removal of the NURF-specific subunit BPTF leads to a strong reduction in chromatin accessibility and SNF2H ATPase localization around CTCF sites. This affects adjacent nucleosome occupancy and CTCF binding. At a group of sites with reduced chromatin accessibility, CTCF binding persists but cohesin occupancy is reduced, resulting in decreased insulation. These results suggest that CTCF binding can be separated from its function as an insulator in nuclear organization and identify a specific role for NURF in mediating SNF2H localization and chromatin opening at bound CTCF sites.
摘要：
模拟开关（ISWI）家族的催化活性对于某些转录因子的核小体组织和DNA结合至关重要，包括绝缘体蛋白CTCF。在这里，我们通过衍生一组等基因小鼠干细胞系来定义单个亚复合物的贡献，每个都缺少六个ISWI辅助子单元之一。CERF中任何一个亚基的个别缺失，RSF,ACF,WICH或NoRC亚复合物仅适度影响染色质景观，而去除NURF特异性亚基BPTF会导致染色质可及性和CTCF位点周围的SNF2HATP酶定位大大降低。这会影响相邻的核小体占有率和CTCF结合。在一组染色质可及性降低的部位，CTCF结合持续存在，但粘附素占用减少，导致绝缘下降。这些结果表明，CTCF结合可以与其在核组织中作为绝缘子的功能分开，并确定NURF在介导SNF2H定位和结合CTCF位点的染色质开放中的特定作用。
