Takasaki Kaoru, Wafula Eric K, Kumar Sara S, Smith David, Sit Ying Ting, Gagne Alyssa L, French Deborah L, Thom Christopher S, Chou Stella T
bioRxiv. 2024 Oct 31:2024.05.24.595827. doi: 10.1101/2024.05.24.595827.
Trisomy 21 (T21), or Down syndrome (DS), is associated with baseline macrocytic erythrocytosis, thrombocytopenia, and neutrophilia, as well as transient abnormal myelopoiesis (TAM) and myeloid leukemia of DS (ML-DS). TAM and ML-DS blasts both arise from an aberrant megakaryocyte-erythroid progenitor and exclusively express GATA1s, the truncated isoform of , while germline mutations in a non-T21 context lead to congenital cytopenia(s) without a leukemic predisposition. This suggests that T21 and GATA1s both perturb hematopoiesis in multipotent progenitors, but studying their individual effects is challenging due to limited access to relevant human progenitor populations. To dissect individual developmental impacts, we used single-cell RNA-sequencing to interrogate hematopoietic progenitor cells (HPCs) from isogenic human induced pluripotent stem cells differing only by chromosome 21 and/or status. The transcriptomes of these HPCs revealed significant heterogeneity and lineage skew dictated by T21 and/or GATA1s. T21 and GATA1s each disrupted temporal regulation of lineage-specific transcriptional programs and specifically perturbed cell cycle genes. Trajectory inference revealed that GATA1s nearly eliminated erythropoiesis, slowed MK maturation, and promoted myelopoiesis in the euploid context, while in T21 cells, GATA1s competed with the enhanced erythropoiesis and impaired megakaryopoiesis driven by T21 to promote production of immature erythrocytes, MKs, and myeloid cells. The use of isogenic cells revealed distinct transcriptional programs that can be attributed specifically to T21 and GATA1s, and how they independently and synergistically result in HPC proliferation at the expense of maturation, consistent with a pro-leukemic phenotype.
21三体综合征（T21），即唐氏综合征（DS），与基线大细胞性红细胞增多、血小板减少和中性粒细胞增多有关，也与唐氏综合征的短暂异常髓系造血（TAM）和髓系白血病（ML-DS）相关。TAM和ML-DS的原始细胞均起源于异常的巨核细胞-红系祖细胞，且仅表达GATA1s（ 的截短异构体），而在非T21背景下的种系 突变会导致先天性血细胞减少且无白血病易感性。这表明T21和GATA1s均会扰乱多能祖细胞中的造血过程，但由于难以获取相关人类祖细胞群体，研究它们各自的作用具有挑战性。为了剖析个体发育影响，我们使用单细胞RNA测序来研究来自仅在21号染色体和/或 状态上不同的同基因人诱导多能干细胞的造血祖细胞（HPC）。这些HPC的转录组显示出由T21和/或GATA1s决定的显著异质性和谱系偏差。T21和GATA1s各自破坏了谱系特异性转录程序的时间调控，并特别扰乱了细胞周期基因。轨迹推断表明，在整倍体背景下，GATA1s几乎消除了红细胞生成，减缓了巨核细胞成熟，并促进了髓系造血，而在T21细胞中，GATA1s与T21驱动的增强的红细胞生成和受损的巨核细胞生成竞争，以促进未成熟红细胞、巨核细胞和髓系细胞的产生。使用同基因细胞揭示了可具体归因于T21和GATA1s的不同转录程序，以及它们如何独立和协同导致HPC增殖而以成熟为代价，这与白血病前期表型一致。
