The transcription factor DDIT3 is a Potential Driver of Dyserythropoiesis in Myelodysplastic Syndromes [Young_Elderly_MDS]. The transcription factor DDIT3 is a Potential Driver of Dyserythropoiesis in Myelodysplastic Syndromes [Young_Elderly_MDS]

Myelodysplastic syndromes (MDS) are clonal hematopoietic stem cell (HSC) malignancies characterized by ineffective hematopoiesis with increased incidence in elderly individuals. Genetic alterations do not fully explain the molecular pathogenesis of the disease, indicating that other types of lesions may play a role in its development. In this work, we analyzed the transcriptional lesions of human HSCs, demonstrating how aging and MDS are characterized by a complex transcriptional rewiring that manifests as diverse linear and non-linear transcriptional dynamisms. While aging-associated lesions seemed to predispose elderly HSCs to myeloid transformation, disease-specific alterations may be involved in triggering MDS development. Among MDS-specific lesions, we detected the overexpression of the transcription factor (TF) DDIT3. Exogenous upregulation of DDIT3 in human healthy HSCs induced an MDS-like transcriptional state, and a delay in erythropoiesis, with an accumulation of cells in early stages of erythroid differentiation, as determined by single-cell RNA-sequencing. Increased DDIT3 expression was associated with downregulation of transcription factors required for normal erythropoiesis, such as KLF1, TAL1 or SOX6, and with a failure in the activation of their erythroid transcriptional programs. Finally, DDIT3 knockdown in CD34+ cells from MDS patients was able to restore erythropoiesis, as demonstrated by immunophenotypic and transcriptional profiling. These results demonstrate that DDIT3 may be a driver of MDS transformation, and a potential therapeutic target to restore the inefficient erythropoiesis characterizing these patients. Overall design: Human HSCs (CD34+ CD38- CD90+ CD45RA-) from healthy young and elderly (>65 years old) individualas, as well as from untreated MDS patients, were analyzed by MARS-seq

骨髓增生异常综合征（Myelodysplastic syndromes, MDS）是一类以无效造血为特征的克隆性造血干细胞（hematopoietic stem cell, HSC）恶性肿瘤，在老年人群中发病率显著升高。目前遗传改变尚无法完全阐明该病的分子发病机制，提示其他类型的病变可能参与其发生发展过程。本研究对人类造血干细胞的转录异常进行了分析，揭示衰老与MDS均存在复杂的转录重编程特征，该重编程表现为多样的线性与非线性转录动态变化。尽管衰老相关的转录异常似乎会使老年造血干细胞易发生髓系转化，但疾病特异性的改变可能参与触发MDS的发生。在MDS特异性的转录异常中，我们检测到转录因子（transcription factor, TF）DDIT3的过表达。在人类健康造血干细胞中外源上调DDIT3可诱导出MDS样转录状态，并延迟红细胞生成，导致红细胞分化早期阶段的细胞蓄积，该结论经单细胞RNA测序（single-cell RNA-sequencing, scRNA-seq）验证。DDIT3表达升高与正常红细胞生成所需的转录因子（如KLF1、TAL1或SOX6）的下调相关，并使其红细胞转录程序无法正常激活。最后，对MDS患者CD34+细胞中的DDIT3进行敲低，可恢复红细胞生成，该结果经免疫表型分型与转录组谱分析证实。综上，本研究证实DDIT3可能是MDS转化的驱动因子，也是恢复此类患者特征性无效造血的潜在治疗靶点。整体实验设计：本研究采用MARS-seq对来自健康青年、老年（>65岁）个体以及未经治疗的MDS患者的人类造血干细胞（CD34+ CD38- CD90+ CD45RA-）进行了测序分析。