Erythropoietin receptor signaling in stress erythropoiesis and erythrocytosis

项目摘要 促红细胞生成素（Epo）及其受体EpoR是红细胞生成的主要调节因子。 正常的Epo水平支持基础红细胞生成。在贫血、失血或缺氧时， 水平上升，启动信号通路，扩大红系祖细胞，增加红细胞 红细胞生成应激反应期间的细胞生成。在已发表的研究中，我们发现 在骨髓增生性疾病中发现的组成型活性JAK 2突变体JAK 2（V617 F）， 肿瘤，需要与EpoR相关联，以传递致癌信号， 红系祖细胞驱动红细胞增多。虽然EpoR信号在更分化的 红细胞前体已经被广泛研究，早期祖细胞中的EpoR信号传导， 其控制应激性红细胞生成和红细胞增多。 在初步研究中，我们发现JAK 2（V617 F）致癌信号需要 远端EpoR胞质结构域。因为EpoR的远端结构域对于压力是必不可少的， JAK 2（V617 F）可能会劫持EpoR， 依赖应激红细胞生成途径来驱动红细胞增多。使用新流程 细胞计数策略，我们确定了一个以前未被识别的早期集落群体， 形成红系祖细胞（CFU-E），我们将其命名为应激CFU-E或sCFU-E，作为一种免疫调节剂。 JAK 2（V617 F）驱动信号和应激促红细胞生成信号的特异性靶点 反应 阐明支持sCFU-E扩增的EpoR信号传导可能揭示新的治疗方法 可以靶向红细胞增多而不影响正常红细胞生成的途径。中央 该提案的目标是表征EpoR依赖性机制， 应激性红细胞生成和JAK 2（V617 F）驱动的红细胞增多中的sCFU-E扩增。 目的1确定sCFU-E扩增中的机制和EpoR信号传导。目的2 利用我们新的RNA-seq数据来检查EpoR下游的新型调节剂， 应激性红细胞生成、鼠红细胞增多症和人真性红细胞增多症。在一起， 这些结果将阐明控制应激红细胞生成的机制， 病理性红细胞增多症，并可能导致新的治疗干预。

PROJECT SUMMARY Erythropoietin (Epo) and its receptor EpoR are primary regulators of erythropoiesis. Normal Epo levels support basal erythropoiesis. In anemia, blood loss, or hypoxia, Epo levels rise, initiating signaling pathways to expand erythroid progenitors, increasing red cell production during the erythropoietic stress response. In published work, we showed that the constitutively active JAK2 mutant JAK2(V617F), found in myeloproliferative neoplasms, needs to associate with the EpoR to transmit oncogenic signaling in erythroid progenitors to drive erythrocytosis. While EpoR signaling in more differentiated erythroid precursors has been extensively studied, EpoR signaling in early progenitors, which controls stress erythropoiesis and erythrocytosis, has not been elucidated. In preliminary studies, we show that JAK2(V617F) oncogenic signaling requires the distal EpoR cytoplasmic domain. Because this distal EpoR domain is essential for stress erythropoiesis but dispensable for basal erythropoiesis, JAK2(V617F) may hijack EpoR- dependent stress erythropoiesis pathways to drive erythrocytosis. Using a new flow cytometry strategy, we identified a previously unrecognized population of early colony- forming erythroid progenitors (CFU-E), which we named stress CFU-E or sCFU-E, as a specific target of both the JAK2(V617F)-driven signals and the stress erythropoietic response. Elucidating EpoR signaling that supports sCFU-E expansion may reveal new therapeutic avenues that can target erythrocytosis while sparing normal erythropoiesis. The central goal of this proposal is to characterize the EpoR-dependent mechanisms that drive sCFU-E expansion in stress erythropoiesis and in JAK2(V617F)-driven erythrocytosis. Aim 1 determines mechanisms and EpoR signaling in sCFU-E expansion. Aim 2 leverages our new RNA-seq data to examine novel regulators downstream of EpoR in stress erythropoiesis, murine erythrocytosis and human polycythemia vera. Together, these results will elucidate mechanisms controlling stress erythropoiesis and pathological erythrocytosis, and may lead to novel therapeutic interventions.