Mehta Charu, Fraga de Andrade Isabela, Matson Daniel R, Dewey Colin N, Bresnick Emery H
Department of Cell and Regenerative Biology, Wisconsin Blood Cancer Research Institute, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA.
Carbone Cancer Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA.
Nucleic Acids Res. 2021 Sep 20;49(16):9007-9025. doi: 10.1093/nar/gkab367.
Cellular differentiation requires vast remodeling of transcriptomes, and therefore machinery mediating remodeling controls differentiation. Relative to transcriptional mechanisms governing differentiation, post-transcriptional processes are less well understood. As an important post-transcriptional determinant of transcriptomes, the RNA exosome complex (EC) mediates processing and/or degradation of select RNAs. During erythropoiesis, the erythroid transcription factor GATA1 represses EC subunit genes. Depleting EC structural subunits prior to GATA1-mediated repression is deleterious to erythroid progenitor cells. To assess the importance of the EC catalytic subunits Dis3 and Exosc10 in this dynamic process, we asked if these subunits function non-redundantly to control erythropoiesis. Dis3 or Exosc10 depletion in primary murine hematopoietic progenitor cells reduced erythroid progenitors and their progeny, while sparing myeloid cells. Dis3 loss severely compromised erythroid progenitor and erythroblast survival, rendered erythroblasts hypersensitive to apoptosis-inducing stimuli and induced γ-H2AX, indicative of DNA double-stranded breaks. Dis3 loss-of-function phenotypes were more severe than those caused by Exosc10 depletion. We innovated a genetic rescue system to compare human Dis3 with multiple myeloma-associated Dis3 mutants S447R and R750K, and only wild type Dis3 was competent to rescue progenitors. Thus, Dis3 establishes a disease mutation-sensitive, cell type-specific survival mechanism to enable a differentiation program.
细胞分化需要转录组进行大规模重塑，因此介导重塑的机制控制着分化过程。相对于调控分化的转录机制，转录后过程的了解较少。作为转录组的一个重要转录后决定因素，RNA外切体复合物（EC）介导特定RNA的加工和/或降解。在红细胞生成过程中，红系转录因子GATA1抑制EC亚基基因。在GATA1介导的抑制之前耗尽EC结构亚基对红系祖细胞是有害的。为了评估EC催化亚基Dis3和Exosc10在这一动态过程中的重要性，我们研究了这些亚基是否以非冗余方式发挥作用来控制红细胞生成。在原代小鼠造血祖细胞中耗尽Dis3或Exosc10会减少红系祖细胞及其后代，而对髓系细胞没有影响。Dis3的缺失严重损害了红系祖细胞和成红细胞的存活，使成红细胞对凋亡诱导刺激高度敏感并诱导γ-H2AX，这表明存在DNA双链断裂。Dis3功能丧失的表型比Exosc10耗尽所导致的表型更严重。我们创新了一种基因拯救系统，以比较人类Dis3与多发性骨髓瘤相关的Dis3突变体S447R和R750K，只有野生型Dis3能够拯救祖细胞。因此，Dis3建立了一种对疾病突变敏感的、细胞类型特异性的存活机制，以实现分化程序。
