Formation of novel CENP-A domains on tandem repetitive DNA and across chromosome breakpoints on human chromosome 8q21 neocentromeres
Formation of novel CENP-A domains on tandem repetitive DNA and across chromosome breakpoints on human chromosome 8q21 neocentromeres
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DOI：
10.1007/s00412-011-0337-6
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发表时间：
2011-12-01
期刊：
影响因子：
1.6
通讯作者：
Warburton, Peter E.
中科院分区：
文献类型：
--
作者：
Hasson, Dan;Alonso, Alicia;Warburton, Peter E.
内源性人类着丝粒形成于串联重复的α卫星DNA的兆碱基大小的阵列上。人类新着丝粒在缺乏α卫星DNA的异位位点表观遗传形成，并允许分析着丝粒DNA和染色质组织。在这项研究中，我们提出了分子细胞遗传学和CENP-A染色质免疫沉淀（ChIP）的两个新着丝粒，已形成在染色体带8 q21每个具有独特的DNA和CENP-A染色质配置的CHIP分析。第一个新着丝粒是在8号新双着丝粒染色体上发现的，该染色体具有失活的内源性着丝粒，其中着丝粒活性和CENP-A结构域被重新定位为在大串联重复DNA上的8 q21条带。这是第一个在重复DNA上形成新着丝粒的例子，因为所有其他映射的新着丝粒都是在单拷贝DNA上形成的。定量荧光原位杂交（FISH）分析显示，与正常8号染色体上的活性着丝粒相比，非活性着丝粒处的α卫星阵列大小减少了60%。这种新双着丝粒染色体可能提供洞察着丝粒失活和串联DNA在着丝粒结构中的作用。第二个新着丝粒被发现在含有8 q21串联重复DNA的新着丝粒环状染色体上，尽管新着丝粒被定位于不同的基因组区域。有趣的是，这个新着丝粒由8 q21和8 q24带中的两个不同的CENP-A结构域组成，它们在环状染色体上更接近。这种新着丝粒表明染色体重排和DNA断裂可能参与新着丝粒的形成。这些新的例子提供了对人类新着丝粒的形成和结构的深入了解。
Endogenous human centromeres form on megabase-sized arrays of tandemly repeated alpha satellite DNA. Human neocentromeres form epigenetically at ectopic sites devoid of alpha satellite DNA and permit analysis of centromeric DNA and chromatin organization. In this study, we present molecular cytogenetic and CENP-A chromatin immunoprecipitation (ChIP) on CHIP analyses of two neocentromeres that have formed in chromosome band 8q21 each with a unique DNA and CENP-A chromatin configuration. The first neocentromere was found on a neodicentric chromosome 8 with an inactivated endogenous centromere, where the centromeric activity and CENP-A domain were repositioned to band 8q21 on a large tandemly repeated DNA. This is the first example of a neocentromere forming on repetitive DNA, as all other mapped neocentromeres have formed on single copy DNA. Quantitative fluorescent in situ hybridization (FISH) analysis showed a 60% reduction in the alpha satellite array size at the inactive centromere compared to the active centromere on the normal chromosome 8. This neodicentric chromosome may provide insight into centromere inactivation and the role of tandem DNA in centromere structure. The second neocentromere was found on a neocentric ring chromosome that contained the 8q21 tandemly repeated DNA, although the neocentromere was localized to a different genomic region. Interestingly, this neocentromere is composed of two distinct CENP-A domains in bands 8q21 and 8q24, which are brought into closer proximity on the ring chromosome. This neocentromere suggests that chromosomal rearrangement and DNA breakage may be involved in neocentromere formation. These novel examples provide insight into the formation and structure of human neocentromeres.