Department of Life Science, Chung-Ang University, Seoul 06974, Korea.
Genes (Basel). 2021 Jan 30;12(2):201. doi: 10.3390/genes12020201.
Uracil is an unavoidable aberrant base in DNA sequences, the repair of which takes place by a highly efficient base excision repair mechanism. The removal of uracil from the genome requires multiple biochemical steps with conformational changes of DNA that inhibit DNA replication and interfere with transcription. However, the relevance of uracil in DNA for cellular physiology and transcriptional regulation is not fully understood. We investigated the functional roles of using knock-down (KD) and knock-out (KO) models. The proliferation ratio of KD and KO cells was decreased compared to WT control cells, and the cell cycle was arrested in the G2/M phases before the transition to mitosis. The apoptotic cell death was increased in KD and KO cell lines through the increase of BAX and active caspase 3 expression. Phospho-gamma-H2AX expression, which reflected accumulated DNA damage, was also increased in KO cells. Moreover, the apoptotic cells by DNA damage accumulation were markedly increased in KD and KO cells after ultraviolet C irradiation. Transcriptomic analysis using RNA-seq revealed that was involved in gene sets expression including cell cycle transition and chromatin silencing. Together, the results implicate SMUG1 as a critical factor in cell cycle and transcriptional regulation.
尿嘧啶是 DNA 序列中不可避免的异常碱基，其修复是通过一种高效的碱基切除修复机制进行的。尿嘧啶从基因组中的去除需要多个生化步骤，伴随着 DNA 的构象变化，这些变化会抑制 DNA 复制并干扰转录。然而，尿嘧啶在 DNA 中的功能及其对细胞生理和转录调控的相关性尚未完全清楚。我们使用敲低（KD）和敲除（KO）模型研究了 的功能作用。与 WT 对照细胞相比， KD 和 KO 细胞的增殖比例降低，并且在向有丝分裂过渡之前，细胞周期被阻滞在 G2/M 期。通过 BAX 和活性 caspase 3 表达的增加，KD 和 KO 细胞系中的细胞凋亡性死亡增加。磷酸化 γ-H2AX 表达（反映累积的 DNA 损伤）在 KO 细胞中也增加。此外，在紫外线 C 照射后，DNA 损伤积累导致的凋亡细胞在 KD 和 KO 细胞中明显增加。使用 RNA-seq 的转录组分析表明， 参与了包括细胞周期转换和染色质沉默在内的基因集表达。总之，这些结果表明 SMUG1 是细胞周期和转录调控的关键因素。
