Greenwood P D, Silver J C, Brown I R
J Neurochem. 1981 Aug;37(2):498-505. doi: 10.1111/j.1471-4159.1981.tb00483.x.
Total cerebral hemisphere nuclei purified from adult rabbit brain were subfractionated into neuronal and glial populations. Previous studies have shown that chromatin in neuronal nuclei is organized in an unusual nucleosome conformation compared with glial or kidney nuclei, i.e., a short DNA repeat length is present. We now analyze whether this difference in chromatin organization is associated with an alteration in the histone component of nucleosomes. Total histone isolated by acid/urea-protamine extraction of purified neuronal, glial, and kidney nuclei was analyzed by electrophoresis on SDS-polyacrylamide slab gels. Histone H1 that was selectively extracted from nuclei was also examined. Differences were not observed on SDS gels in the electrophoretic mobilities of histones associated with either the nucleosome core particle (histones (H2A, H2B, H3, H4) or the nucleosome linker region (histone H1). Total histone and selectively extracted histone H1 were also analyzed on acid/urea slab gels that resolve histones on the basis of both molecular weight and charge differences. When analyzed in this system, differences with respect to electrophoretic mobility were not detected when comparing either selectively extracted histone H1 or total histone from neuronal and glial nuclei. Quantitative analyses were also performed and neuronal nuclei were found to contain less histone H1 per milligram DNA compared with glial or kidney nuclei. Neuronal nuceli also demonstrated a lower ratio of histone H1/core histone. These results suggest that the pronounced difference in chromatin organization in neuronal compared with glial nuclei, which is reflected by a short DNA repeat length in neurons, appears to be associated with quantitative differences in neuronal histone H1.
从成年兔脑中纯化得到的全脑半球核被进一步细分为神经元群体和神经胶质细胞群体。先前的研究表明，与神经胶质细胞核或肾细胞核相比，神经元细胞核中的染色质以一种不寻常的核小体构象存在，即存在较短的DNA重复长度。我们现在分析这种染色质组织上的差异是否与核小体组蛋白成分的改变有关。通过酸/尿素-鱼精蛋白提取法从纯化的神经元核、神经胶质细胞核和肾细胞核中分离得到的总组蛋白，在SDS-聚丙烯酰胺平板凝胶上进行电泳分析。还检测了从细胞核中选择性提取的组蛋白H1。在SDS凝胶上，与核小体核心颗粒（组蛋白（H2A、H2B、H3、H4））或核小体连接区（组蛋白H1）相关的组蛋白的电泳迁移率未观察到差异。总组蛋白和选择性提取的组蛋白H1也在酸/尿素平板凝胶上进行分析，该凝胶根据分子量和电荷差异来分辨组蛋白。当在这个系统中进行分析时，比较从神经元核和神经胶质细胞核中选择性提取的组蛋白H1或总组蛋白时，未检测到电泳迁移率方面的差异。还进行了定量分析，发现与神经胶质细胞核或肾细胞核相比，神经元细胞核每毫克DNA中含有的组蛋白H1较少。神经元核还显示出组蛋白H1/核心组蛋白的比例较低。这些结果表明，神经元细胞核与神经胶质细胞核在染色质组织上的显著差异，表现为神经元中较短的DNA重复长度，似乎与神经元组蛋白H1的定量差异有关。
