Epigenetic control of preimplantation embryo development

描述(申请人提供)：组蛋白修饰的动态变化是配子染色质向胚胎染色质转变的基础。这些变化被认为是启动胚胎基因转录和获得多能性所必需的。这些转变中的异常很可能导致植入前早期的胚胎停滞。早期胚胎死亡是导致奶牛和人类不孕的主要原因。在牛胚胎中，组蛋白H3赖氨酸27的甲基化是动态重塑的表观遗传标记之一。组蛋白H3赖氨酸27的三甲基化与转录沉默有关。我们推测，组蛋白H3赖氨酸27去甲基酶JMJD3是去除H3K27甲基化标记所必需的，这反过来又允许启动胚胎基因转录和正常胚胎发育。为了验证这一假设，我们将通过注射siRNA诱导牛卵母细胞和植入前胚胎中JMJD3的下调。具体目标1将确定母系遗传的JMJD3是否是正常牛胚胎发育所必需的。特定目的2将利用染色质免疫沉淀来评估JMJD3在胚胎基因组激活时组蛋白甲基化重编程中的作用。特异靶3旨在通过使用RNA-Seq分析早期胚胎的转录组来研究JMJD3在基因组激活中的作用。总之，这些实验将扩大我们对胚胎发育基本机制的理解。这些信息将有助于开发诊断工具和干预措施，以治疗动物和人类的不孕症。此外，揭示卵母细胞引发的核重新编程机制将有助于提高体细胞核移植的成功，以产生用于农业和生物医学的克隆动物和用于再生医学的自体干细胞。

DESCRIPTION (provided by applicant): Dynamic changes in histone modification underlie the transition of gametic chromatin to embryonic chromatin. These changes are thought to be required for initiation of embryonic gene transcription and acquisition of pluripotency. Abnormalities in these transitions are likely to result in embryonic arrest at early preimplantation stages. Early embryonic mortality is a major cause of infertility in dairy cattle and humans. In bovine embryos, methylation of histone H3 lysine 27 is one of the epigenetic marks that are dynamically remodeled. Trimethylation of histone H3 lysine 27 is associated with silencing of transcription. We hypothesize that JMJD3, a histone H3 lysine 27 demethylases, is required for removal of methylation marks from H3K27, which in turn allows the initiation of embryonic gene transcription and normal embryo development. To test this hypothesis we will induce downregulation of JMJD3 in bovine oocytes and preimplantation embryos by siRNA injection. Specific Aim 1 will determine whether maternally inherited JMJD3 is required for normal bovine embryonic development. Specific Aim 2 will make use of chromatin immunoprecipitation to assess the role of JMJD3 on histone methylation reprogramming at the time of embryonic genome activation. Specific aim 3 is designed to examine the role of JMJD3 on genome activation by analyzing the transcriptome of early embryos using RNA-Seq. Together; these experiments will expand our understanding of the basic mechanisms underlying embryonic development. This information will aid in developing diagnostic tools and interventions to treat infertility disorders in animals and people. Also, uncovering the nuclear reprogramming mechanisms elicited by the oocyte will help improve the success of somatic cell nuclear transfer for the generation of cloned animals for agricultural and biomedical applications and autologous stem cells for regenerative medicine applications.