红细胞终末分化期出现与珠蛋白基因表达增强子HS2序列特异结合的蛋白质因子

APPEARANCE OF SOME NOVEL PROTEINS BINDING ENHANCER ELEMENT OF GLOBIN GENE(HS_2)DURING ERYTHROID TERMINAL DIFFERENTIATION

利用Ｓｏｕｔｈｗｅｓｔｅｒｎ印迹和电泳迁移率改变分析法，研究了处于终末分化阶段的人胚肝中、晚幼红细胞和经ｈｅｍｉｎ诱导分化前后的Ｋ５６２细胞核抽提物中与地高辛标记的ＨＳ２探针特异结合的蛋白质。发现经ｈｅｍｉｎ诱导后的Ｋ５６２细胞样品中出现一些为诱导前缺如的，分子量为１２，１４，１８，４５和５０ｋＤ的ＨＳ２结合蛋白。这些结合蛋白在印迹图谱中的位置（分子量大小）与存在于正常终末分化期红细胞中ＨＳ２结合蛋白的相近。同样，诱导后Ｋ５６２细胞核蛋白质与ＨＳ２形成复合物的电泳迁移图谱与正常分化的人胚肝红细胞核蛋白质－ＨＳ２复合物的相似，而与未经诱导的Ｋ５６２细胞核蛋白质－ＨＳ２复合物的迁移图谱存在差异。提示诱导分化和正常分化的红细胞表达一些新的ＨＳ２结合蛋白，这些仅在终末分化期红细胞中出现的ＨＳ２结合蛋白，可能是参与红细胞分化和珠蛋白基因表达调控的重要因素。

Using digoxiginin labeled HS2 as a probe, we have performed Southwestern bolt and gel retardation analysis for determination of HS2 binding proteins in the nuclear extracts which isolated from the intermediate and late erythroblasts of human fetal liver,and from the human erythroleukemia(K562)cells before and after hemin induction. The results indicated that HS2-binding proteins with molecular weights of 12,14,18,45,and 50 kD were detectable in the induced differentiating cell nuclear extract.These proteins were also appeared in intermediate and late erythroblasts at terminal differentiation stage,but were not observed in uninduced nuclear extract.Gel retardation ana1ysis demonstrated that the pattern of bands generated by induced and uninduced nuclear extract was distinctively different from each other, but was identical to those from the intermediate and late erythroblasts of human fetal liver.These results indicated that some nuclear proteins which were only expressed during terminal differentiation of erythroid cells might interact with HS2 sequence directly of indirectly to form the HS2-protein multimeric complexes and thus play an important role in the globin gene regulation and erythroid differentiation.