SWI/SNF inactivation in the endometrial epithelium leads to loss of epithelial integrity [12Z RNA-seq]. SWI/SNF inactivation in the endometrial epithelium leads to loss of epithelial integrity [12Z RNA-seq]

Although ARID1A mutations are a hallmark feature, mutations in other SWI/SNF (SWItch/Sucrose Non-Fermentable) chromatin remodeling subunits are also observed in endometrial neoplasms. Here, we interrogated the roles of Brahma/SWI2-related gene 1 (BRG1, SMARCA4), the SWI/SNF catalytic subunit, in the endometrial epithelium. BRG1 loss affects more than one-third of all active genes and highly overlaps with the ARID1A gene regulatory network. Chromatin immunoprecipitation studies revealed widespread subunit-specific differences in transcriptional regulation, as BRG1 promoter interactions are associated with gene activation, while ARID1A binding is associated with gene repression. However, we identified a physiologically relevant subset of BRG1 and ARID1A co-regulated epithelial identity genes. Mice were genetically engineered to inactivate BRG1 specifically in the endometrial epithelium. Endometrial glands were observed embedded in uterine myometrium, indicating adenomyosis-like phenotypes. Molecular similarities were observed between BRG1 and ARID1A mutant endometrial cells in vivo, including loss of epithelial cell adhesion and junction genes. Collectively, these studies illustrate overlapping contributions of multiple SWI/SNF subunit mutations in the translocation of endometrium to distal sites, with loss of cell integrity being a common feature in SWI/SNF mutant endometrial epithelia. Overall design: Human 12Z endometriotic epithelial cells were transfected with either siBRG1 or non-targeting siRNA control and assayed 72 hours post-transfection via RNA-seq.

尽管ARID1A突变是子宫内膜肿瘤的标志性特征，但其他SWI/SNF（SWItch/Sucrose Non-Fermentable）染色质重塑亚基的突变也可在子宫内膜肿瘤中检出。本研究探究了BRAHMA/SWI2相关基因1（BRG1，SMARCA4）——SWI/SNF催化亚基——在子宫内膜上皮中的功能。BRG1缺失会影响超过三分之一的活跃基因，且其基因调控网络与ARID1A的调控网络高度重叠。染色质免疫沉淀实验显示，转录调控中存在广泛的亚基特异性差异：BRG1与启动子的结合与基因激活相关，而ARID1A的结合则与基因抑制相关。不过，本研究鉴定出了一类具有生理相关性的BRG1与ARID1A共同调控的上皮特征基因。我们通过基因工程手段构建了在子宫内膜上皮中特异性失活BRG1的小鼠模型。镜下可见子宫肌层内嵌入子宫内膜腺体，提示出现类似子宫腺肌症的表型。体内实验中，BRG1与ARID1A突变的子宫内膜细胞存在分子相似性，包括上皮细胞黏附与连接相关基因的表达缺失。综上，本系列研究表明，多个SWI/SNF亚基突变可协同促进子宫内膜异位至远端位点，而细胞完整性丢失是SWI/SNF突变型子宫内膜上皮的共同特征。整体实验设计：将人源12Z子宫内膜异位上皮细胞分别转染siBRG1或非靶向siRNA对照，并于转染72小时后通过RNA-seq进行转录组检测分析。