Analysis of DNA (cytosine 5) methyltransferase mRNA sequence and expression in bovine preimplantation embryos, fetal and adult tissues
Analysis of DNA (cytosine 5) methyltransferase mRNA sequence and expression in bovine preimplantation embryos, fetal and adult tissues
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DOI：
10.1016/s1567-133x(03)00121-2
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发表时间：
2003-10-01
影响因子：
1.2
通讯作者：
Westhusin, ME
中科院分区：
文献类型：
--
作者：
Golding, MC;Westhusin, ME
哺乳动物植入前发育是建立基因组甲基化模式的关键阶段，负责此的酶的适当功能似乎对于正常发育至关重要。迄今为止，绝大多数有关 DNA 胞嘧啶 5-甲基转移酶 (Dnmts) 发育表达的工作都是在小鼠中进行的。在这里，我们报告了 Dnmt 家族在牛植入前和胎儿发育过程中的序列和表达。牛 Dnmt mRNA 与人类和小鼠的 mRNA 表现出很强的序列同源性，并且与其他物种相似，以多种亚型存在。其中两个剪接变体被称为 Dnmt2gamma 和 Dnmt3a4，代表了以前未报道的序列组合。这里介绍的工作表明早期牛胚胎表达编码 Dnmt1 体细胞形式的 mRNA，并且该转录物与核糖体分离。与小鼠模型不同，编码从头甲基转移酶、Dnmt3a 和 3b 的 mRNA 存在于植入前发育过程中，也可以在核糖体亚细胞部分中找到。此外，实时PCR分析结果表明，不同组织类型之间以及胎儿阶段和成年阶段之间Dnmt mRNA表达水平存在显着差异。最近，有人推测，在克隆胚胎中观察到的异常甲基化可能部分归因于植入前发育过程中 Dnmt1o 同工型的错误表达。这里提出的工作提出了新的、重要的假设，必须考虑这些假设，既涉及在正常发育过程中指导表观遗传编程的 DNA 甲基转移酶的核心，又涉及克隆胚胎中异常 DNMT 表达的含义。 (C) 2003 Elsevier B.V. 保留所有权利。
Mammalian preimplantation development is a critical stage for establishment of the genomic methylation pattern and proper function of the enzymes responsible for this appear essential for normal development. To date, the vast majority of work concerning the developmental expression of the DNA cytosine 5-methyltansferases (Dnmts) has been conducted in mice. Here we report the sequence and expression of the Dnmt family during bovine preimplantation and fetal development. Bovine Dnmt mRNAs display strong sequence homology to those of human and mouse and similar to other species, exist as multiple isoforms. Two of these splice variants, which have been termed Dnmt2gamma and Dnmt3a4, represent previously unreported sequence combinations. Work presented here demonstrates early bovine embryos express mRNA coding for the somatic form of Dnmt1 and that this transcript fractionates with the ribosome. Unlike the murine model, mRNA encoding the de novo methyltransferases, Dnmt3a and 3b are present during preimplantation development and can also be found in the ribosomal subcellular fraction. Further, results of Real Time PCR analysis indicate significant differences in Dnmt mRNA expression levels exist among different tissue types as well as between fetal and adult stages. Recently, it has been postulated that the cause of abnormal methylation observed in cloned embryos may be due in part to misexpression of the Dnmt1o isoform during preimplantation development. Work presented here raises new and significant hypotheses that must be considered both regarding the cadre of DNA methyltranferases that direct epigenetic programming during normal development and regarding the implication of abnormal DNMT expression in cloned embryos. (C) 2003 Elsevier B.V. All rights reserved.