Erythropoietin receptor-dependent erythroid colony-forming unit development: capacities of Y343 and phosphotyrosine-null receptor forms.
Erythropoietin receptor-dependent erythroid colony-forming unit development: capacities of Y343 and phosphotyrosine-null receptor forms.
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DOI：
10.1182/blood.v99.3.898
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发表时间：
2002-02
期刊：
影响因子：
20.3
通讯作者：
Chris P. Miller;Destin W. Heilman;D. Wojchowski
中科院分区：
文献类型：
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作者：
Chris P. Miller;Destin W. Heilman;D. Wojchowski
红细胞发育依赖于促红细胞生成素（EPO）与红细胞集落形成单位（CFUe）表达的受体的结合以及随后受体结合Janus激酶（Jak 2）的激活。然后Jak 2介导受体酪氨酸位点的磷酸化和25个或更多Src同源2结构域编码蛋白和相关因子的募集。先前的研究表明，含有Jak 2结合结构域加上单个磷酸酪氨酸（343）（PY（343））-STAT 5结合位点的EPO受体形式提供红系细胞发育所需的所有信号。然而，PY（343）和STAT 5的作用仍然存在争议，并且关于PY-无效受体活性和STAT 5缺陷小鼠中的红细胞生成的发现是不同的。为了研究原代细胞中PY-无效EPO受体的活性，同时避免补偿机制，在转基因小鼠中从GATA 1基因衍生的载体表达一种保留Jak 2结合和活化结构域但缺乏所有胞质酪氨酸位点的形式，作为人表皮生长因子受体-鼠EPO受体嵌合体（EE-T-Y343 F）。在来自经甲砜霉素处理的小鼠的CFUe中研究了该受体形式的生物信号传导能力。有趣的是，这种PY-无效EPO受体形式支持CFUe发育（在不存在可检测的STAT 5活化的情况下），其效率在EE-T-Y343形式或内源性EPO受体介导的那些水平的3倍内。然而，EE-T-Y343 F依赖性Ter 119（+）成红细胞成熟减弱。在与c-Kit的共信号转导测试中，EE-T-Y343 F仍然保留了与c-Kit协同促进红系祖细胞增殖的全部能力。因此，EPO受体PY依赖性事件可以辅助晚期红细胞生成，但对于EPO受体-c-Kit协同作用可能是不必要的。
Red cell development depends on the binding of erythropoietin (EPO) to receptors expressed by erythroid colony-forming units (CFUe) and the subsequent activation of receptor-bound Janus kinase (Jak2). Jak2 then mediates the phosphorylation of receptor tyrosine sites and the recruitment of 25 or more Src homology 2 domain-encoding proteins and associated factors. Previous studies have shown that an EPO receptor form containing Jak2-binding domains plus a single phosphotyrosine(343) (PY(343))-STAT5-binding site provides all signals needed for erythroid cell development. However, roles for PY(343) and STAT5 remain controversial, and findings regarding PY-null receptor activities and erythropoiesis in STAT5-deficient mice are disparate. To study activities of a PY-null EPO receptor in primary cells while avoiding compensatory mechanisms, a form retaining domains for Jak2 binding and activation, but lacking all cytoplasmic tyrosine sites, was expressed in transgenic mice from a GATA1 gene-derived vector as a human epidermal growth factor receptor- murine EPO receptor chimera (EE-T-Y343F). The bio-signaling capacities of this receptor form were investigated in CFUe from thiamphenicol-treated mice. Interestingly, this PY-null EPO receptor form supported CFUe development (in the absence of detectable STAT5 activation) at efficiencies within 3-fold of those levels mediated by either an EE-T-Y343 form or the endogenous EPO receptor. However, EE-T-Y343F-dependent Ter119(+) erythroblast maturation was attenuated. In tests of cosignaling with c-Kit, EE-T-Y343F nonetheless retained full capacity to synergize with c-Kit in promoting erythroid progenitor cell proliferation. Thus, EPO receptor PY-dependent events can assist late erythropoiesis but may be nonessential for EPO receptor-c-Kit synergy.