Corepressors negatively regulate gene expression by chromatin compaction. Targeted regulation of gene expression could provide a means to control endothelial cell phenotype. We hypothesize that by targeting corepressor proteins, endothelial angiogenic function can be improved. To study this, the expression and function of nuclear corepressors in human umbilical vein endothelial cells (HUVEC) and in murine organ culture was studied. RNA-seq revealed that nuclear receptor corepressor 1 (NCoR1), silencing mediator of retinoid and thyroid hormone receptors (SMRT) and repressor element-1 silencing transcription factor (REST) are the highest expressed corepressors in HUVECs. Knockout and knockdown strategies demonstrated that the depletion of NCoR1 increased the angiogenic capacity of endothelial cells, whereas depletion of SMRT or REST did not. Interestingly, the effect was VEGF signaling independent. NCoR1 depletion significantly upregulated angiogenesis-associated genes, especially tip cell genes, including , and , as observed by RNA- and ATAC-seq. Confrontation assays comparing cells with and without NCoR1-deficiency revealed that loss of NCoR1 promotes a tip-cell position during spheroid sprouting. Moreover, a proximity ligation assay identified NCoR1 as a direct binding partner of the Notch-signaling-related transcription factor RBPJk. Luciferase assays showed that siRNA-mediated knockdown of promotes RBPJk activity. Furthermore, NCoR1 depletion prompts upregulation of several elements in the Notch signaling cascade. Downregulation of , but not , prevented the positive effect of knockdown on spheroid outgrowth. Collectively, these data indicate that decreasing expression is an attractive approach to promote angiogenic function.

中文翻译：

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NCoR1 通过改变 Notch 信号传导来限制血管生成能力

辅阻遏物通过染色质压缩负向调节基因表达。基因表达的靶向调控可以提供控制内皮细胞表型的方法。我们假设通过靶向辅阻遏蛋白，可以改善内皮血管生成功能。为了研究这一点，我们研究了人脐静脉内皮细胞（HUVEC）和小鼠器官培养物中核辅阻遏物的表达和功能。RNA-seq 显示，核受体辅阻遏物 1 (NCoR1)、类视黄醇和甲状腺激素受体沉默介导物 (SMRT) 以及阻遏元件 1 沉默转录因子 (REST) 是 HUVEC 中表达量最高的辅阻遏物。敲除和敲除策略表明，NCoR1 的缺失增加了内皮细胞的血管生成能力，而 SMRT 或 REST 的缺失却没有。有趣的是，该效应与 VEGF 信号传导无关。通过 RNA 和 ATAC-seq 观察到，NCoR1 缺失显着上调血管生成相关基因，尤其是尖端细胞基因，包括 、 和 。比较具有和不具有 NCoR1 缺陷的细胞的对抗实验表明，NCoR1 的缺失会促进球状体萌芽过程中尖端细胞的位置。此外，邻近连接测定将 NCoR1 鉴定为 Notch 信号相关转录因子 RBPJk 的直接结合伴侣。荧光素酶测定表明 siRNA 介导的敲低可促进 RBPJk 活性。此外，NCoR1 的缺失会促使 Notch 信号级联中的多个元件上调。的下调，但不会阻止击倒对球体生长的积极影响。总的来说，这些数据表明减少表达是促进血管生成功能的一种有吸引力的方法。