A 210-kb segment of tandem repeats and Retroelements located between imprinted subdomains of mouse distal chromosome 7
A 210-kb segment of tandem repeats and Retroelements located between imprinted subdomains of mouse distal chromosome 7
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DOI：
10.1093/dnares/11.5.325
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发表时间：
2004-10-31
期刊：
影响因子：
4.1
通讯作者：
Sasaki, H
中科院分区：
文献类型：
--
作者：
Shirohzu, H;Yokomine, T;Sasaki, H
哺乳动物的基因组印记往往形成簇，并受到长距离机制的调控。小鼠7号染色体的远端印迹结构域与人类11号染色体11p15.5的Beckwith-Wiedemann综合征结构域相邻，至少包含13个印迹基因。该结构域由两个亚结构域组成，分别受印记中心的调控。我们在这里报告的0.6 Mb区域的成品质量序列，包括更多的着丝粒亚结构域。该序列包含4个印迹基因（Ascl2/Mash2、Ins2、Igf2和H19），并揭示了以前未鉴定的CpG岛和串联重复序列，这可能是印迹基因的特征。最有趣的是，一个独特的210 kb的片段组成的串联重复序列和retroelements几乎完全确定。该片段位于Th和Ins2之间，具有异染色质形成DNA的特征，并且在CpG位点高度甲基化。该片段在亲本染色体上表现出异步复制，这是印记域的一个特征。我们建议，这个重复片段可以作为两个子域之间的边界或作为表观遗传染色质修饰的目标，调节印迹。
Mammalian genes subject to genomic imprinting often form clusters and are regulated by long-range mechanisms. The distal imprinted domain of mouse chromosome 7 is orthologous to the Beckwith-Wiedemann syndrome domain in human chromosome 11p15.5 and contains at least 13 imprinted genes. This domain consists of two subdomains, which are respectively regulated by an imprinting center. We here report the finished-quality sequence of a 0.6-Mb region encompassing the more centromeric subdomain. The sequence contains four imprinted genes (Ascl2/Mash2, Ins2, Igf2 and H19) and reveals previously unidentified CpG islands and tandem repeats, which may be features of imprinted genes. Most interestingly, a unique 210-kb segment consisting almost exclusively of tandem repeats and retroelements is identified. This segment, located between Th and Ins2, has features of heterochromatin-forming DNA and is highly methylated at CpG sites. The segment exhibits asynchronous replication on the parental chromosomes, a feature of the imprinted domains. We propose that this repeat segment could serve either as a boundary between the two subdomains or as a target for epigenetic chromatin modifications that regulate imprinting.