Lineage-specific imprinting and evolution of the zinc-finger gene ZIM2
Lineage-specific imprinting and evolution of the zinc-finger gene ZIM2
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DOI：
10.1016/j.ygeno.2004.02.007
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发表时间：
2004-07-01
期刊：
影响因子：
4.4
通讯作者：
Stubbs, L
中科院分区：
文献类型：
--
作者：
Kim, J;Bergmann, A;Stubbs, L
我们使用源自人类、小鼠和牛的序列，对包含两个印记基因 PEG3 和 ZIM2 的 100 kb 基因组区间进行了深入的比较分析。在所有三种哺乳动物中，ZIM2 与 PEG3 的基因组距离相似且方向相同，表明该印迹基因座的基本结构保守性。然而，一些谱系特异性的变化已经发生，影响了 ZIM2 的外显子结构和印记状态。人类 ZIM2 和 PEG3 共享一组 5' 外显子和一个共同的启动子，并且两个基因都是父系表达。相比之下，小鼠和牛的 Zim2 基因不与 Peg3 共享 5' 外显子，并且 Zim2 在这两个物种中都采用单独的下游启动子。 Zim2 的印记状态在哺乳动物中也不保守。小鼠 Zim2 在睾丸中双等位基因表达，但主要来自大脑中的母体等位基因，而牛 Zim2 在睾丸中双等位基因表达。 Zim2 和 Peg3 的单独转录以及启动子使用和印记状态的变化似乎是由独立插入事件引起的，这些插入事件分别将不相关的基因 Zim1 和 Ast1 放置在小鼠和牛的 Zim2 和 Peg3 之间。我们的结果表明，PEG3 和 ZIM2 代表该位点的两个原始基因，并且在最近的进化时期，重排在不同的哺乳动物谱系中独立发生。我们的数据还表明，人类 PEG3 和 ZIM2 的外显子共享不是祖先的，但可能代表融合事件，连接两个相邻基因并使 ZIM2 处于父本表达控制之下。鉴于其他印记结构域的典型结构和功能保守性，这些观察结果是引人注目的，并表明 PEG3/ZIM2 印记结构域可能以不寻常的谱系特异性模式进化。由爱思唯尔公司出版
We have carried out an in-depth comparative analysis of a 100-kb genomic interval containing two imprinted genes, PEG3 and ZIM2, using sequences derived from human, mouse, and cow. In all three mammals, ZIM2 is located at a similar genomic distance and in the same orientation relative to PEG3, indicating the basic structural conservation of this imprinted locus. However, several lineage-specific changes have occurred that affect the exon structure and imprinting status of ZIM2. Human ZIM2 and PEG3 share a set of 5' exons and a common promoter, and both genes are paternally expressed. In contrast, mouse and cow Zim2 genes do not share 5' exons with Peg3, and Zim2 employs a separate downstream promoter in both species. The imprinting status of Zim2 is also not conserved among mammals; mouse Zim2 is expressed biallelically in testis but predominantly from the maternal allele in brain, while cow Zim2 is expressed biallelically in testis. The separate transcription of Zim2 and Peg3 and the change in promoter usage and imprinting status appear to have resulted from independent insertional events that have placed unrelated genes, Zim1 and Ast1, respectively, between Zim2 and Peg3 in mouse and cow. Our results suggest that PEG3 and ZIM2 represent the two original genes at this locus and that rearrangements have occurred independently in different mammalian lineages in recent evolutionary times. Our data also suggest that exon-sharing of human PEG3 and ZIM2 was not ancestral, but may represent a fusion event joining, the two neighboring genes and bringing ZIM2 under paternal expression control. These observations are striking in light of the structural and functional conservation that typifies other imprinted domains and suggest that the PEG3/ZIM2 imprinted domain may have evolved in an unusual lineage-specific pattern. Published by Elsevier Inc.