急性骨髓性白血病（AML）患者中的血小板减少症是一种重要且致命的并发症，其起因于白血病巢穴和白血病干细胞对巨核造血过程的干扰。我们之前的研究发现，AML骨髓中升高的白细胞介素4（IL-4）对包括造血干细胞（HSCs）在内的巨核造血各个阶段产生了不良影响，但具体机制尚不清楚。在本研究中，我们进行了单细胞转录组分析，并发现IL-4Rα高表达vs IL-4Rα低表达的HSCs中激活的氧化应激途径和凋亡途径。体外的IL-4刺激导致HSCs的凋亡和巨核细胞相关转录因子的下调。功能实验显示IL-4Rα高表达的HSCs对tunicamycin和辐射诱导的凋亡更为敏感，表明其对内质网应激损伤更加脆弱。为了阐明IL-4的下游信号，我们分析了AML骨髓中HSCs的转录组，发现蛋白酶体成分Psmd13显著下调，其表达对于巨核红细胞发育是必需的，但可以被体外的IL-4抑制。我们通过shRNA对HSCs进行Psmd13沉默，发现他们的重建能力和巨核细胞分化能力严重受损，在体内增加了凋亡。总结起来，我们的研究揭示了IL-4-Psmd13信号在HSCs的抗应激能力和巨核细胞分化能力中具有以前未被认识的调控作用。© 2023. Springer Nature Limited.

Thrombocytopenia is a major and fatal complication in patients with acute myeloid leukemia (AML), which results from disrupted megakaryopoiesis by leukemic niche and blasts. Our previous research revealed that elevated interleukin-4 (IL-4) in AML bone marrow had adverse impact on multiple stages throughout megakaryopoiesis including hematopoietic stem cells (HSCs), but the specific mechanism remains unknown. In the present study, we performed single-cell transcriptome analysis and discovered activated oxidative stress pathway and apoptosis pathway in IL-4Rαhigh versus IL-4Rαlow HSCs. IL-4 stimulation in vitro led to apoptosis of HSCs and down-regulation of megakaryocyte-associated transcription factors. Functional assays displayed higher susceptibility of IL-4Rαhigh HSCs to tunicamycin and irradiation-induced apoptosis, demonstrating their vulnerability to endoplasmic reticulum (ER) stress injury. To clarify the downstream signaling of IL-4, we analyzed the transcriptomes of HSCs from AML bone marrow and found a remarkable down-regulation of the proteasome component Psmd13, whose expression was required for megakaryocytic-erythroid development but could be inhibited by IL-4 in vitro. We knocked down Psmd13 by shRNA in HSCs, and found their repopulating capacity and megakaryocytic differentiation were severely compromised, with increased apoptosis in vivo. In summary, our study uncovered a previous unrecognized regulatory role of IL-4-Psmd13 signaling in anti-stress and megakaryocytic differentiation capability of HSCs.© 2023. Springer Nature Limited.