Epigenetic Variation in Mice with Defective Imprinting

描述（申请人提供）：基因组印记是一种分子过程，通过不同的表观遗传标记区分基因的母本和父本等位基因。这个过程的核心是产生差异甲基化结构域（DMD），其中一个亲本等位基因是甲基化的，而另一个等位基因是未甲基化的。DMD通过两步机制发展，其中DNA胞嘧啶甲基化模式（印记）首先置于亲本等位基因之一上（取决于基因在卵母细胞或精子中），然后维持（遗传）这种表观遗传修饰。DMD控制着发育中的胎儿和相关的胚外组织中的大多数（如果不是全部的话）印记基因的印记。我们的研究结果表明，在植入前发育过程中DMD序列上甲基化标记的维持对印迹过程至关重要，从而对发育中的胚胎至关重要。本提案的主要目的是研究DNMT1 DNA胞嘧啶甲基转移酶，DNMT1o和DNMT1s，在这个维护过程中的作用。DNMT1s在体细胞中表达，DNMT1o是一种卵母细胞衍生的DNMT1变体，在卵母细胞中表达，也在植入前发育过程中表达。这些研究分为两个目的，每个目的都针对一个特定的假设：（1）我们在这里假设，在植入前发育过程中基因组印记的遗传取决于卵母细胞和合子衍生的DNMT 1蛋白的维持甲基化活性。关于DNMT1o和DNMT1s的着床前作用的假设将在各种实验中进行测试，检查Dnmt 1基因突变对小鼠ES细胞中基因组印记维持的影响。(2)我们在这里假设，DNMT1o和DNMT1s蛋白质的特定区域参与基因组印记的遗传，并且这些区域的特定功能可以通过在体内研究适当的DNMT1突变体来推断。 公共卫生相关性：基因组印记是一种通过不同的表观遗传标记来区分基因的母本和父本等位基因的分子过程。我们的研究结果表明，在植入前发育过程中，某些DNA序列上甲基化标记的维持对印迹过程至关重要，从而对发育中的胚胎至关重要。本提案的主要目的是研究DNMT1 DNA胞嘧啶甲基转移酶，DNMT1o和DNMT1s，在这个维护过程中的作用。

DESCRIPTION (provided by applicant): Genomic imprinting is a molecular process that distinguishes, with different epigenetic marks, the maternal and paternal alleles of genes. Central to this process is the creation of differentially methylated domains (DMDs) in which one parental allele is methylated and the opposite allele is unmethylated. DMDs develop through a two- step mechanism in which a DNA cytosine methylation pattern (imprint) is first placed on one of the parental alleles (in oocyte or sperm depending on the gene) and this epigenetic modification is then maintained (inherited). DMDs govern the imprinting of most, if not all, of the imprinted genes in the developing fetus and associated extraembryonic tissues. Our results indicate that the maintenance of methylation marks on DMD sequences during preimplantation development is crucial to the imprinting process and thus to the developing embryo. The main objective of this proposal is to study the roles of the DNMT1 DNA cytosine methyltransferases, DNMT1o and DNMT1s, in this maintenance process. DNMT1s is expressed in somatic cells and DNMT1o is an oocyte-derived DNMT1 variant that is expressed in oocytes and also during preimplantation development. The studies are divided into two Aims, each addressing a specific hypothesis: (1) We hypothesize here that the inheritance of genomic imprints during preimplantation development depends on maintenance methylation activities of both oocyte- and zygote-derived DNMT1 proteins. Hypotheses regarding the preimplantation roles of DNMT1o and DNMT1s will be tested in a variety of experiments examining the effect of Dnmt1 gene mutations on the maintenance of genomic imprints in mouse ES cells. (2) We hypothesize here that specific regions of the DNMT1o and DNMT1s proteins are involved in the inheritance of genomic imprints, and that the specific functions of these regions can be deduced by studying appropriate DNMT1 mutants in vivo. PUBLIC HEALTH RELEVANCE: Genomic imprinting is a molecular process that distinguishes, with different epigenetic marks, the maternal and paternal alleles of genes. Our results indicate that the maintenance of methylation marks on certain DNA sequences during preimplantation development is crucial to the imprinting process and thus to the developing embryo. The main objective of this proposal is to study the roles of the DNMT1 DNA cytosine methyltransferases, DNMT1o and DNMT1s, in this maintenance process.