Production of erythrocytes, granulocytes and megakaryocytes by gp130 signalling and related molecular mechanisms.

促红细胞生成素（EPO）是红细胞生成的主要体液调节因子，以前没有其他因子支持造血干细胞中红细胞的增殖和终末成熟。我们发现，重组人可溶性IL-6受体（sIL-6R）和IL-6联合刺激gp130可以支持含干细胞因子（SCF）或flk2/flt3配体的纯化人CD34^+细胞在缺乏EPO的情况下的增殖、分化和红细胞的终末成熟。在同一培养物中加入抗gp130单克隆抗体而不加入抗epo单克隆抗体，完全消除了红细胞的产生。这些结果清楚地表明，成熟的红细胞可以在体外无EPO的造血祖细胞中产生。HML/SE是从M7白血病儿童中建立的gm - csf或scf依赖性细胞系。虽然HML/SE细胞既不能增殖，也不能单独存在EPO，但这些细胞可以通过重组人sIL-6R和IL-6的组合增殖并产生血红蛋白。SCF和gp130的激活激活了人EPO受体启动子，诱导了EPO受体基因的表达。综上所述，我们推测HML/SE细胞通过SCF和gp130信号诱导的EPO受体获得对EPO的反应性。对人EPO受体启动子中可能的转录因子结合位点的突变分析表明，Spl而不是GATA-1结合位点参与了hEPOR基因的诱导。虽然有充分的文献证明造血干细胞和原始祖细胞需要一种早期作用的细胞因子和一种特定的细胞因子来分化到某一谱系，但相关的机制尚不清楚。加上先前的报道，人类血清中含有可检测水平的il - 6r、IL-6和SCF，正常的红细胞生成可能通过两种不同的生理途径调节；epo介导的信号传导以及gp130与c-KIT联合信号传导的新机制。少

Eryhropoietin(EPO) is the primary humoral regulator of erythropoiesis and no other factor has previously been reported to support proliferation and terminal maturation of erythroid cells from hemopoietic stem cells. We found that stimulation of gp130 by a combination of recombinant human soluble IL-6 receptor (sIL-6R) and IL-6 can support proliferation, differentiation and terminal maturation of erythroid cells in the absence of EPO from purified human CD34^+ cells in suspensin culture containing stem cell factor (SCF) or flk2/flt3 ligand. The addition of anti-gp130 mAbs but not anti-EPO Ab to the same culture completely abrogated the generation of erythroid cells. These results clearly demonstrate that mature erythroid cells can be emerged from hemopoietic progenitors without EPO in vitro. HML/SE is a GM-CSF-or SCF-dependent cell line established from a children with M7 leukemia. Although HML/SE cells neither proliferate nor in the presense of EPO alone, these cells can proliferate an … More d produce hemoglobin by a combinaation of recombinant human sIL-6R and IL-6. SCF and activation of gp130 activated the human EPO receptor promoter and induced EPO receptor gene expression. Taken together, we speculate that HML/SE cells acquired responsiveness to EPO via the EPO receptor induced by SCF and gp130 signallings. Mutation analysis of putative transcription factor binding sites in the human EPO receptor promoter suggested that Spl, rather than the GATA-1 binding site, contributed to the induction of the hEPOR gene. While it is well documented that hematopoietic stem cells and primitive progenitors require both an early-actimg cytokine and a kineage specific cytokine to differntiate to a certain lineage, related mechanisms are not well understood. Together with the previous reports that human sera contain derectable levels of sIL-6R,IL-6 and SCF,normal erythropoiesis may be regulated physiologically by two different pathways ; the EPO-mediated signalling and a novel mechanism with gp130 in combination with c-KIT signalling. Less