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Abstract：
In vertebrates, SMARCAD1 participates in transcriptional regulation, heterochromatin maintenance, DNA repair, and replication. The molecular basis underlying its involvement in these processes is not well understood. We identified the RNA polymerase III general transcription factor TFIIIC as an interaction partner of native SMARCAD1 in mouse and human models using endogenous co-immunoprecipitations. TFIIIC has dual functionality, acting as a general transcription factor and as a genome organizer separating chromatin domains. We found that its partnership with SMARCAD1 is conserved across different mammalian cell types, from somatic to pluripotent cells. Using purified proteins, we confirmed that their interaction is direct. A gene expression analysis suggested that SMARCAD1 is dispensable for TFIIIC function as an RNA polymerase III transcription factor in mouse ESCs. The distribution of TFIIIC and SMARCAD1 in the ESC genome is distinct, and unlike in yeast, SMARCAD1 is not enriched at active tRNA genes. Further analysis of SMARCAD1-binding partners in pluripotent and differentiated mammalian cells reveals that SMARCAD1 associates with several factors that have key regulatory roles in chromatin organization, such as cohesin, laminB, and DDX5. Together, our work suggests for the first time that the SMARCAD1 enzyme participates in genome organization in mammalian nuclei through interactions with architectural proteins.
摘要：
在脊椎动物中，SMARCAD1参与转录调控，异染色质维持，DNA修复,和复制。其参与这些过程的分子基础尚不清楚。我们使用内源性共免疫沉淀将RNA聚合酶III通用转录因子TFIIIC鉴定为小鼠和人类模型中天然SMARCAD1的相互作用伴侣。TFIIIC具有双重功能，作为一般转录因子和基因组组织者分离染色质结构域。我们发现它与SMARCAD1的伙伴关系在不同的哺乳动物细胞类型中是保守的，从体细胞到多能细胞。使用纯化的蛋白质，我们确认他们的互动是直接的。基因表达分析表明，SMARCAD1对于TFIIIC功能作为小鼠ESC中的RNA聚合酶III转录因子是不必要的。TFIIC和SMARCAD1在ESC基因组中的分布是不同的，与酵母不同，SMARCAD1在活性tRNA基因上不富集。对多能和分化的哺乳动物细胞中SMARCAD1结合配偶体的进一步分析显示，SMARCAD1与在染色质组织中具有关键调节作用的几个因素相关，比如cohesin，laminB,DDX5一起,我们的工作首次表明SMARCAD1酶通过与结构蛋白的相互作用参与哺乳动物细胞核的基因组组织.
