Hartman Emily S, Brindley Elena C, Papoin Julien, Ciciotte Steven L, Zhao Yue, Peters Luanne L, Blanc Lionel
Laboratory of Developmental Erythropoiesis, Center for Autoimmune, Musculoskeletal and Hematopoietic Diseases, The Feinstein Institute for Medical Research, Manhasset, NY, United States.
Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Hempstead, NY, United States.
Front Physiol. 2018 Jun 5;9:689. doi: 10.3389/fphys.2018.00689. eCollection 2018.
RASA3 is a Ras GTPase activating protein that plays a critical role in blood formation. The autosomal recessive mouse model (severe combined anemia and thrombocytopenia) carries a missense mutation in . Homozygotes present with a phenotype characteristic of bone marrow failure that is accompanied by alternating episodes of crisis and remission. The mechanism leading to impaired erythropoiesis and peripheral cell destruction as evidenced by membrane fragmentation in is unclear, although we previously reported that the mislocalization of RASA3 to the cytosol of reticulocytes and mature red cells plays a role in the disease. In this study, we further characterized the bone marrow failure in and found that RASA3 plays a central role in cell cycle progression and maintenance of reactive oxygen species (ROS) levels during terminal erythroid differentiation, without inducing apoptosis of the precursors. In mice undergoing crises, there is a consistent pattern of an increased proportion of cells in the G/G phase at the basophilic and polychromatophilic stages of erythroid differentiation, suggesting that RASA3 is involved in the G checkpoint. However, this increase in G is transient, and either resolves or becomes indiscernible by the orthochromatic stage. In addition, while ROS levels are normal early in erythropoiesis, there is accumulation of superoxide levels at the reticulocyte stage (DHE increased 40% in = 0.02) even though mitochondria, a potential source for ROS, are eliminated normally. Surprisingly, apoptosis is significantly decreased in the bone marrow at the proerythroblastic (15.3%; = 0.004), polychromatophilic (8.5%; = 0.01), and orthochromatic (4.2%; = 0.02) stages. Together, these data indicate that ROS accumulation at the reticulocyte stage, without apoptosis, contributes to the membrane fragmentation observed in . Finally, the cell cycle defect and increased levels of ROS suggest that is a model of bone marrow failure with characteristics of aplastic anemia.
RASA3是一种Ras GTP酶激活蛋白，在血液形成过程中起关键作用。常染色体隐性小鼠模型（严重联合贫血和血小板减少症）在……携带一个错义突变。纯合子表现出骨髓衰竭的表型特征，并伴有危机和缓解的交替发作。尽管我们之前报道RASA3在网织红细胞和成熟红细胞的细胞质中定位错误在该疾病中起作用，但导致红细胞生成受损和外周细胞破坏（如……中膜碎片所示）的机制尚不清楚。在本研究中，我们进一步对……中的骨髓衰竭进行了特征描述，发现RASA3在终末红细胞分化过程中的细胞周期进程和活性氧（ROS）水平维持中起核心作用，而不会诱导前体细胞凋亡。在经历危机的……小鼠中，在红细胞分化的嗜碱性和多染性阶段，处于G/G期的细胞比例增加呈现出一致的模式，这表明RASA3参与了G期检查点。然而，G期的这种增加是短暂的，到正染性阶段要么消失要么变得难以察觉。此外，虽然在红细胞生成早期ROS水平正常，但在网织红细胞阶段超氧化物水平会积累（在……中DHE增加40%，P = 0.02），尽管作为ROS潜在来源的线粒体正常消除。令人惊讶的是，在早幼红细胞阶段（15.3%；P = 0.004）、多染性阶段（8.5%；P = 0.01）和正染性阶段（4.2%；P = 0.02），……小鼠骨髓中的凋亡显著减少。总之，这些数据表明在网织红细胞阶段ROS积累但无凋亡，导致了……中观察到的膜碎片。最后，细胞周期缺陷和ROS水平升高表明……是一种具有再生障碍性贫血特征的骨髓衰竭模型。
