Imprinting regulation of the murine Meg1/Grb10 and human GRB10 genes;: roles of brain-specific promoters and mouse-specific CTCF-binding sites
Imprinting regulation of the murine Meg1/Grb10 and human GRB10 genes;: roles of brain-specific promoters and mouse-specific CTCF-binding sites
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DOI：
10.1093/nar/gkg232
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发表时间：
2003-03-01
影响因子：
14.9
通讯作者：
Ishino, F
中科院分区：
文献类型：
--
作者：
Hikichi, T;Kohda, T;Ishino, F
印迹小鼠基因Meg 1/Grb 10在几乎所有的组织和器官中由母系等位基因表达，除了在脑中，其以双等位基因形式表达，并且父系等位基因在成年期优先表达。相比之下，人GRB 10基因在几乎所有组织和器官中显示相等的双等位基因表达，而它几乎总是在胎儿脑中表达。为了阐明人类和小鼠不同组织和器官之间复杂印记模式的分子机制，我们详细分析了这些物种的基因组结构和组织特异性表达谱。使用5 '-RACE和RT-PCR的实验证明了在人和小鼠中存在新的脑特异性启动子，其中仅父本等位基因是活性的。启动子位于主要差异甲基化区域。有趣的是，CTCF结合位点仅在小鼠启动子区发现，CTCF显示DNA甲基化敏感的结合活性。因此，CTCF的绝缘子功能可能导致Meg 1/Grb 10基因在小鼠中从另一个上游启动子的相互母体表达，而人类上游启动子由于在该区域缺乏相应的绝缘子序列而在两个亲本等位基因中均具有活性。
The imprinted mouse gene Meg1/Grb10 is expres sed from maternal alleles in almost all tissues and organs, except in the brain, where it is expressed biallelically, and the paternal allele is expressed preferentially in adulthood. In contrast, the human GRB10 gene shows equal biallelic expression in almost all tissues and organs, while it is almost always expressed paternally in the fetal brain. To elucidate the molecular mechanisms of the complex imprinting patterns among the different tissues and organs of humans and mice, we analyzed in detail both the genomic structures and tissue-specific expression profiles of these species. Experiments using 5'-RACE and RT-PCR demonstrated the existence in both humans and mice of novel brain- specific promoters, in which only the paternal allele was active. The promoters were located in the primary differentially methylated regions. Interest ingly, CTCF-binding sites were found only in the mouse promoter region where CTCF showed DNA methylation-sensitive binding activity. Thus, the insulator function of CTCF might cause reciprocal maternal expression of the Meg1/Grb10 gene from another upstream promoter in the mouse, whereas the human upstream promoter is active in both parental alleles due to the lack of the corresponding insulator sequence in this region.