Parreira L, Telhada M, Ramos C, Hernandez R, Neves H, Carmo-Fonseca M
Institute of Histology and Embryology, Faculty of Medicine, University of Lisbon, Portugal.
Hum Genet. 1997 Oct;100(5-6):588-94. doi: 10.1007/s004390050558.
The three-dimensional positioning of immunoglobulin (Ig) genes within the nucleus of human cells was investigated using in situ hybridization and confocal microscopy. The visualization of heavy and light chain genes in B-lymphoid cells showed that the three Ig genes are differentially and nonrandomly distributed in different nuclear subvolumes: the kappa genes were found to be preferentially confined to an outer nuclear volume, whereas the gamma and lambda genes consistently occupied more central positions within the nucleus, the lambda genes being more interior when compared with the gamma genes. The data further show that these overall topographical distributions are independent of gene transcriptional activity and are conserved in different cell types. Although subtle gene movements within those defined topographical regions cannot be excluded by this study, the results indicate that tissue specificity of gene expression is not accompanied by drastic changes in gene nuclear topography, rather suggesting that gene organization within the nucleus may be primarily dependent on structural constraints imposed on the respective chromosomes.
利用原位杂交和共聚焦显微镜技术，研究了免疫球蛋白（Ig）基因在人类细胞核内的三维定位。对B淋巴细胞中重链和轻链基因的可视化观察表明，三种Ig基因在不同的核亚体积中呈差异且非随机分布：κ基因优先局限于核外周区域，而γ和λ基因始终占据细胞核内更中心的位置，与γ基因相比，λ基因位置更靠内。数据进一步表明，这些总体拓扑分布与基因转录活性无关，且在不同细胞类型中保守。尽管本研究不能排除在这些定义的拓扑区域内基因存在细微移动，但结果表明基因表达的组织特异性并非伴随着基因在细胞核内拓扑结构的剧烈变化，而是提示细胞核内的基因组织可能主要依赖于各染色体所施加的结构限制。
