SMUG1 promotes telomere maintenance through telomerase RNA end-processing. SMUG1 promotes telomere maintenance through telomerase RNA end-processing

Single-strand selective uracil DNA-glycosylase (SMUG1) associates with the DKC1-H/ACA ribonucleoprotein complex, which is essential for telomerase biogenesis. We show herein, that SMUG1 interacts with the telomerase RNA component, hTERC, and is required for co-transcriptional processing of the nascent transcript towards mature hTERC. We demonstrate that SMUG1 regulates the presence of base modifications between the CR4/CR5 region and the H-box situated towards the 3´-end of hTERC. Increased levels of hTERC base modifications are accompanied by reduced DKC1 binding. Loss of SMUG1 leads to an imbalance between mature hTERC and its processing intermediates, leading to the accumulation of 3´-polyadenylated and 3´-extended intermediates that are degraded in an EXOSC10-independent RNA degradation pathway. Consequently, SMUG1-deprived cells, present telomerase deficiency leading to impaired bone marrow proliferation in SMUG1-knockout mice. Overall design: Analysis of differential expressed genes in HAP1 SMUG1 WT and SMUG1 KO cells generated by deep sequencing (in triplicate).

单链选择性尿嘧啶DNA糖苷酶（Single-strand selective uracil DNA-glycosylase，SMUG1）可与DKC1-H/ACA核糖核蛋白复合物结合，该复合物对端粒酶的生物发生至关重要。我们在此证实，SMUG1可与端粒酶RNA组分hTERC结合，并参与新生转录本向成熟hTERC的共转录加工过程。我们证实，SMUG1可调控hTERC 3'端CR4/CR5区域与H盒之间的碱基修饰水平。hTERC碱基修饰水平升高时，DKC1的结合能力会相应降低。SMUG1缺失会打破成熟hTERC与其加工中间体之间的平衡，导致3'端多聚腺苷酸化及3'端延伸的中间体大量积累，此类中间体可通过不依赖EXOSC10的RNA降解途径被降解。因此，SMUG1缺失细胞会出现端粒酶功能缺陷，进而导致SMUG1敲除小鼠的骨髓增殖能力受损。实验整体设计：对通过深度测序（三次生物学重复）获得的HAP1细胞中SMUG1野生型（Wild Type, WT）与SMUG1敲除型（Knockout, KO）细胞的差异表达基因进行分析。