Clustering of multiple specific genes and gene-rich R-bands around SC-35 domains: evidence for local euchromatic neighborhoods.
Clustering of multiple specific genes and gene-rich R-bands around SC-35 domains: evidence for local euchromatic neighborhoods.
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DOI：
10.1083/jcb.200303131
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发表时间：
2003-09-15
影响因子：
7.8
通讯作者：
Lawrence, Jeanne B
中科院分区：
文献类型：
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作者：
Shopland, Lindsay S;Johnson, Carol V;Byron, Meg;McNeil, John;Lawrence, Jeanne B
通常，真核细胞核包含10 - 30个显著的区域（在此称为SC - 35区域），这些区域集中了mRNA代谢因子。在此，我们表明多个特定基因聚集在一个共同的SC - 35区域周围，该区域包含多种mRNA。非同源基因能够与一个共同区域相关联，但区域“选择”似乎是随机的，即使对于两个协同表达的基因也是如此。在不同染色体臂上广泛分离的活性基因经常与同一区域相关联，随机分布到与一个区域接触的染色体周边的3 - 4个子区域中。最重要的是，对六个单独染色体带的观察表明，大的基因组片段（约5 Mb）在与区域相关的组织上存在显著差异。某些带显示出广泛的接触，经常与SC - 35区域对齐或环绕它，而其他带则没有。所有三个富含基因的反转带都比基因贫乏的吉姆萨深带更明显地表现出这种情况，并且形态测量分析显示出统计学上的显著差异。同样，晚复制的DNA通常避开SC - 35区域。这些发现为染色体带中基因聚集提出了一个功能性的理论基础，这与基因和SC - 35区域在核内的聚集有关。我们提出SC - 35区域是众多聚集基因的功能中心，形成局部常染色质“邻域”，而不是剪接因子的随机储存库，也不是在单个高活性基因上积累的因子。
Typically, eukaryotic nuclei contain 10–30 prominent domains (referred to here as SC-35 domains) that are concentrated in mRNA metabolic factors. Here, we show that multiple specific genes cluster around a common SC-35 domain, which contains multiple mRNAs. Nonsyntenic genes are capable of associating with a common domain, but domain “choice” appears random, even for two coordinately expressed genes. Active genes widely separated on different chromosome arms associate with the same domain frequently, assorting randomly into the 3–4 subregions of the chromosome periphery that contact a domain. Most importantly, visualization of six individual chromosome bands showed that large genomic segments (∼5 Mb) have striking differences in organization relative to domains. Certain bands showed extensive contact, often aligning with or encircling an SC-35 domain, whereas others did not. All three gene-rich reverse bands showed this more than the gene-poor Giemsa dark bands, and morphometric analyses demonstrated statistically significant differences. Similarly, late-replicating DNA generally avoids SC-35 domains. These findings suggest a functional rationale for gene clustering in chromosomal bands, which relates to nuclear clustering of genes with SC-35 domains. Rather than random reservoirs of splicing factors, or factors accumulated on an individual highly active gene, we propose a model of SC-35 domains as functional centers for a multitude of clustered genes, forming local euchromatic “neighborhoods.”