A NOVEL NONHISTONE PROTEIN (MENT) PROMOTES NUCLEAR COLLAPSE AT THE TERMINAL STAGE OF AVIAN ERYTHROPOIESIS
A NOVEL NONHISTONE PROTEIN (MENT) PROMOTES NUCLEAR COLLAPSE AT THE TERMINAL STAGE OF AVIAN ERYTHROPOIESIS
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DOI：
10.1016/0014-4827(92)90379-m
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发表时间：
1992-02-01
影响因子：
3.7
通讯作者：
KRASHENINNIKOV, IA
中科院分区：
文献类型：
--
作者：
GRIGORYEV, SA;SOLOVIEVA, VO;KRASHENINNIKOV, IA
有核鸡红细胞分化的终末阶段与整体基因阻遏和被阻遏的染色质部分的浓缩有关。双向DNP电泳已被用于分离成熟鸡红细胞的转录活性和抑制染色质。抑制的染色质部分被证明是丰富的组蛋白H5，以及与42 kDa的非组蛋白染色体蛋白。42 kDa的蛋白质在这里指定为MENT（成熟红细胞核终止阶段特异性蛋白）是在鸡红细胞生成的终末阶段高表达，并在成年鸡红细胞核中积累。用离子交换层析法从红细胞核的0.4MNaCl提取物中纯化该蛋白。它似乎是一种碱性多肽（pI9.2），然而，在低pH下沉淀。当在体外与未成熟的红细胞核重组时，MENT促进完整的核染色质的凝聚，并增强核酸酶消化的多核小体的溶解，从而模仿体内红细胞成熟的最后阶段发生的过程。特异性基因序列从经MENT处理的细胞核中的核基质中解离的程度与它们的转录活性显著相关。在与MENT（蛋白质/ DNA = 0.005）相同的水平下，添加到核制备物中的其他碱性蛋白质（H5、细胞色素c、RNA酶A）对核组织没有任何影响。当MENT与成红细胞和具有很少或没有组蛋白H5的非红细胞核混合时，没有观察到改变。我们认为，MENT与组蛋白H5合作，完成成熟有核红细胞的核塌陷。
The terminal stage of differentiation of nucleated chicken erythrocytes is associated with an overall gene repression and a condensation of the repressed chromatin portion. Two-dimensional DNP electrophoresis has been used to separate transcriptionally active and repressed chromatin of mature chicken erythrocytes. The repressed chromatin fraction is shown to be enriched with histone H5 as well as with a 42-kDa nonhistone chromosomal protein. The 42-kDa protein designated here as MENT (mature erythrocyte nuclear termination stage-specific protein) is hyperexpressed at the terminal stage of chicken erythropoiesis and is accumulated in adult chicken erythrocyte nuclei. This protein was purified by ion-exchange chromatography from 0.4MNaCl extracts of the erythrocyte nuclei. It appeared to be a basic polypeptide (pI9.2) which, however, precipitated at low pH. When reconstitutedin vitrowith immature erythrocyte nuclei, MENT promoted condensation of intact nuclear chromatin and enhanced the solubilization of nuclease-digested polynucleo-somes, thus mimicking the processes occuringin vivoat the final stage of erythrocyte maturation. The extent of dissociation of specific gene sequences from the nuclear matrix in MENT-treated nuclei is in striking correlation with their transcriptional activity. No other basic proteins (H5, cytochrome c, RNase A) added to the nuclear preparation at the same level as MENT (protein/ DNA = 0.005) caused any effect on nuclear organization. No alterations were observed when MENT was mixed with erythroblasts and nonerythroid nuclei having little or no histone H5. We propose that MENT cooperates with histone H5 to complete the nuclear collapse in mature nucleated erythrocytes.