Institute of Molecular Biology and Tumor Research, Philipps University Marburg, 35043 Marburg, Germany.
CMC Development, R&D, Sanofi, 65926 Frankfurt, Germany.
Genes (Basel). 2023 Sep 13;14(9):1793. doi: 10.3390/genes14091793.
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.
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法，在小鼠和人类模型中鉴定出 RNA 聚合酶 III 通用转录因子 TFIIIC 是天然 SMARCAD1 的相互作用伙伴。TFIIIC 具有双重功能，既作为通用转录因子，又作为分离染色质域的基因组组织者。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，我们证实它们的相互作用是直接的。基因表达分析表明，SMARCAD1 在小鼠 ESC 中作为 RNA 聚合酶 III 转录因子的 TFIIIC 功能是可有可无的。TFIIIC 和 SMARCAD1 在 ESC 基因组中的分布是不同的，与酵母不同，SMARCAD1 不在活跃的 tRNA 基因处富集。对多能和分化的哺乳动物细胞中 SMARCAD1 结合伙伴的进一步分析表明，SMARCAD1 与几个在染色质组织中具有关键调节作用的因子结合，如黏连蛋白、核纤层蛋白 B 和 DDX5。总之，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核基因组组织。
