Department of Genetics, Harvard University, Boston, MA, USA; Division of Hematology/Oncology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA; Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA; Broad Institute of MIT and Harvard, Cambridge, MA, USA.
Department of Genetics, Harvard University, Boston, MA, USA.
Dev Cell. 2023 Oct 23;58(20):2112-2127.e4. doi: 10.1016/j.devcel.2023.07.018. Epub 2023 Aug 15.
Controlled release of promoter-proximal paused RNA polymerase II (RNA Pol II) is crucial for gene regulation. However, studying RNA Pol II pausing is challenging, as pause-release factors are almost all essential. In this study, we identified heterozygous loss-of-function mutations in SUPT5H, which encodes SPT5, in individuals with β-thalassemia. During erythropoiesis in healthy human cells, cell cycle genes were highly paused as cells transition from progenitors to precursors. When the pathogenic mutations were recapitulated by SUPT5H editing, RNA Pol II pause release was globally disrupted, and as cells began transitioning from progenitors to precursors, differentiation was delayed, accompanied by a transient lag in erythroid-specific gene expression and cell cycle kinetics. Despite this delay, cells terminally differentiate, and cell cycle phase distributions normalize. Therefore, hindering pause release perturbs proliferation and differentiation dynamics at a key transition during erythropoiesis, identifying a role for RNA Pol II pausing in temporally coordinating the cell cycle and erythroid differentiation.
调控 RNA 聚合酶 II（RNA Pol II）转录起始后暂停的释放对于基因调控至关重要。然而，由于暂停释放因子几乎都是必需的，因此研究 RNA Pol II 暂停是具有挑战性的。在这项研究中，我们在患有β-地中海贫血症的个体中发现了编码 SPT5 的 SUPT5H 杂合功能丧失突变。在健康人类细胞的红细胞生成过程中，细胞周期基因高度暂停，因为细胞从祖细胞向前体细胞过渡。当通过 SUPT5H 编辑重现致病突变时，RNA Pol II 暂停释放会全局受到干扰，并且当细胞开始从祖细胞向前体细胞过渡时，分化会延迟，伴随着红细胞特异性基因表达和细胞周期动力学的短暂滞后。尽管存在这种延迟，但细胞仍会终末分化，细胞周期相分布会恢复正常。因此，阻碍暂停释放会扰乱红细胞生成过程中关键过渡时的增殖和分化动态，这表明 RNA Pol II 暂停在协调细胞周期和红细胞分化的时间方面发挥作用。
