Non-random radial higher-order chromatin arrangements in nuclei of diploid human cells
Non-random radial higher-order chromatin arrangements in nuclei of diploid human cells
复制标题
DOI：
10.1023/a:1012495201697
复制
发表时间：
2001-10-01
影响因子：
2.6
通讯作者：
Cremer, T
中科院分区：
文献类型：
--
作者：
Cremer, M;von Hase, J;Cremer, T
在具有三维（3D）保存的不同形状的细胞核的人类细胞类型中进行了高阶染色质排列的定量比较。这些细胞类型包括二倍体羊水细胞和成纤维细胞的扁椭圆形核以及来自外周血的B和T淋巴细胞的球形核。用染色体涂料探针对大（#1-5）和小（#17-20）常染色体以及两条性染色体进行荧光原位杂交（FISH）。其他探针描绘了许多较大和较小的人类染色体的异染色质块。形状差异与高阶染色质排列的明显差异相关：在球形淋巴细胞核中，我们注意到3D核内部中小的基因密集的#17、19和20染色体区域（CT）的优先定位-通常与核膜没有任何明显的连接。相反，基因贫乏的小染色体#18和Y的CT明显附着在核膜上。大染色体的CT也优先位于核周边。在羊水细胞和成纤维细胞的椭圆形核中，所有检测的CT均显示附着于核膜的上部和/或下部：小染色体的CT，包括#18和Y，位于核投影（CNP）的中心，而大染色体位于2D核边缘。与这些高度可重复的放射状排列相反，同源和异源CT的异染色质块之间测量的2D距离是显著可变的。这些结果以及CT绘画让我们得出结论，所研究的细胞类型中的核功能可能不需要特定同源或非同源CT的可再现并排排列。在假设每个染色体的DNA含量与其CT体积之间存在线性相关性的情况下，对球形核中46个人类CT的统计排列进行了3D建模。在一组模拟的细胞核中，我们注意到较小的CT朝向3D外围和较大的CT朝向3D中心的优先定位。这种分布与实验观察到的淋巴细胞核中的分布形成鲜明对比。我们的结论是，目前未知的因素（拓扑约束以外）可能发挥决定性的作用，以执行不同的径向排列观察到的大，小CT在椭圆形和球形的人类细胞核。
A quantitative comparison of higher-order chromatin arrangements was performed in human cell types with three-dimensionally (3D) preserved, differently shaped nuclei. These cell types included flat-ellipsoid nuclei of diploid amniotic fluid cells and fibroblasts and spherical nuclei of B and T lymphocytes from peripheral human blood. Fluorescence in-situ hybridization (FISH) was performed with chromosome paint probes for large (#1-5) and small (#17-20) autosomes, and for the two sex chromosomes. Other probes delineated heterochromatin blocks of numerous larger and smaller human chromosomes. Shape differences correlated with distinct differences in higher order chromatin arrangements: in the spherically shaped lymphocyte nuclei we noted the preferential positioning of the small, gene dense #17, 19 and 20 chromosome territories (CTs) in the 3D nuclear interior - typically without any apparent connection to the nuclear envelope. In contrast, CTs of the gene-poor small chromosomes #18 and Y were apparently attached at the nuclear envelope. CTs of large chromosomes were also preferentially located towards the nuclear periphery. In the ellipsoid nuclei of amniotic fluid cells and fibroblasts, all tested CTs showed attachments to the upper and/or lower part of the nuclear envelope: CTs of small chromosomes, including #18 and Y, were located towards the centre of the nuclear projection (CNP), while the large chromosomes were positioned towards the 2D nuclear rim. In contrast to these highly reproducible radial arrangements, 2D distances measured between heterochromatin blocks of homologous and heterologous CTs were strikingly variable. These results as well as CT painting let us conclude that nuclear functions in the studied cell types may not require reproducible side-by-side arrangements of specific homologous or non-homologous CTs. 3D-modelling of statistical arrangements of 46 human CTs in spherical nuclei was performed under the assumption of a linear correlation between DNA content of each chromosome and its CT volume. In a set of modelled nuclei, we noted the preferential localization of smaller CTs towards the 3D periphery and of larger CTs towards the 3D centre. This distribution is in clear contrast to the experimentally observed distribution in lymphocyte nuclei. We conclude that presently unknown factors (other than topological constraints) may play a decisive role to enforce the different radial arrangements of large and small CTs observed in ellipsoid and spherical human cell nuclei.