Erythropoietin receptor signaling in stress erythropoiesis and erythrocytosis

项目总结 健康的成年人通过基础红细胞生成过程每秒产生200万个红细胞。 红细胞生成不足会导致贫血，这是一个重大的全球人类健康问题。在.期间 再生或“应激红细胞生成”为了从贫血中恢复，红细胞的生成进一步增加。压力 红细胞生成对于手术、化疗、骨髓移植和感染的康复至关重要； 然而，潜在的机制仍不清楚。基础红细胞生成和应激性红细胞生成均受 促红细胞生成素及其受体EPOR。EPO与EPOR结合激活相关酪氨酸激酶 JAK2，启动下游信号，导致红系细胞存活、增殖和分化。 虽然EPOR信号在更多分化的红系前体中已经被广泛研究，但EPOR信号 在早期的祖先中还没有被阐明。 这一建议是基于我们最近发现的一个以前没有被发现的早期殖民地形成的种群 红系祖细胞(CFU-E)，我们称之为应激性CFU-E或sCFU-E。SCFU-E是EPO的目标，仅 在红系应激中扩张，对红血球的恢复至关重要。SCFU-E也被劫持 激活JAK2突变体JAK2(V617F)以促进骨髓增生性肿瘤的红细胞生成。在预赛中 研究发现，sCFU-E的增殖和分化涉及新的EPO/EPOR信号通路。我们 发现EPO诱导调节细胞氧化的NADP(H)磷酸酶Nocturin的表达 应激促进sCFU-E增殖。EPO还能诱导抗坏血酸(维生素C)SLC23A2的表达 SCFU-E中的传送器。SCFU-E积累高水平的抗坏血酸，抗坏血酸加速sCFU-E 差异化。这项提议的目的是阐明诺克特林和抗坏血酸驱动的机制 应激性红细胞生成和红细胞增多背景下sCFU-E的增殖和分化。目标1将 确定抗坏血酸进口对sCFU-E功能的作用。目标2将阐明潜在的机制 抗坏血酸依赖的sCFU-E分化。目标3将确定夜曲蛋白和氧化应激的作用 SCFU-E增殖中的信号转导。这些结果将阐明控制应激性红细胞生成和 红细胞增多症，并可能导致针对贫血和那些可以靶向的新的治疗干预措施 红细胞增多症，同时保留基础红细胞生成。

PROJECT SUMMARY Healthy adults produce 2 million erythrocytes every second through the process of basal erythropoiesis. Insufficient erythrocyte production causes anemia, which is a significant global human health problem. During regeneration or “stress erythropoiesis” to recover from anemia, erythrocyte production further increases. Stress erythropoiesis is critical for recovery from surgery, chemotherapy, bone marrow transplantation and infection; however, the underlying mechanisms remain unclear. Both basal and stress erythropoiesis are regulated by erythropoietin (Epo) and its receptor EpoR. Epo binding to the EpoR activates the associated tyrosine kinase JAK2, which initiate downstream signaling leading to survival, proliferation and differentiation of erythroid cells. While EpoR signaling in more differentiated erythroid precursors has been extensively studied, EpoR signaling in early progenitors has not been elucidated. This proposal is based on our recent findings of a previously unrecognized population of early colony-forming erythroid progenitors (CFU-E), which we named stress CFU-E or sCFU-E. sCFU-E are targets of Epo, are only expanded in erythroid stress, and are essential for recovery of the erythron. sCFU-E are also hijacked by the activating JAK2 mutant, JAK2(V617F), to drive erythrocytosis in myeloproliferative neoplasms. In preliminary studies, we discovered that sCFU-E proliferation and differentiation involve novel Epo/EpoR signaling. We found that Epo induces expression of Nocturnin, a NADP(H) phosphatase that regulates cellular oxidative stress to promote sCFU-E proliferation. Epo also induces expression of SLC23A2, an ascorbate (Vitamin C) transporter, in sCFU-E. sCFU-E accumulates high levels of ascorbate, and ascorbate accelerates sCFU-E differentiation. The goal of this proposal is to elucidate the mechanism by which Nocturnin and ascorbate drive proliferation and differentiation of sCFU-E in the context of stress erythropoiesis and erythrocytosis. Aim 1 will determine the role of ascorbate import on sCFU-E function. Aim 2 will elucidate mechanisms underlying ascorbate-dependent sCFU-E differentiation. Aim 3 will determine the role of Nocturnin and oxidative stress signaling in sCFU-E proliferation. These results will elucidate mechanisms controlling stress erythropoiesis and erythrocytosis, and may lead to novel therapeutic interventions for anemia and those that can target erythrocytosis while preserving basal erythropoiesis.