Conditional knockout effects of SMCHD1 in oocytes and embryos

在哺乳动物中，在生命之初就缺乏调节转录的能力。这一基本能力是 在早期分裂阶段通过形成转录抑制的染色质状态而获得的 (TRCs)，其中转录增强子首先变得必要。不久之后，成立了TRCS 受精之所以至关重要，有两个原因：1)抑制内源转座子的激活是重要的 元素，这些元素如果被激活可能会致突变，以及2)正确执行正确的 胚胎存活率的转录程序。这包括激活和抑制数千个基因 四个连续的胚胎基因组激活波(EGA1至4)。未能建立TRCS和 调节EGA波可以正确杀死胚胎。 我们发现，含有蛋白质1的染色体柔性铰链域的结构维持 (Smchd1)是一种母性效应基因，可能协调所有这些事件。Smchd1)促销 EGA1终止，2)涉及抑制在EGA2至4期间上调的基因，以及3) 支持内细胞团(ICM)的形成和胚胎存活率揭示早期Smchd1的长期影响 行为。我们的总体模型是，卵母细胞表达的Smchd1终止EGA1，并帮助建立 TRCs允许在EGA2期间进行正确的基因调控。胚胎表达的Smchd1然后维持和 延长基因抑制，并实现对胚胎存活所需的EGA3和EGA4的最佳控制。这个 因此，对Smchd1作用机制的研究为发现基本原理提供了一个重要的新入口 调节胚胎基因组功能和活力的机制。 我们创造了一种新的花状Smchd1等位基因，可以用来实现卵母细胞特异性的去势。 Smchd1发挥作用，因此产生的胚胎缺乏Smchd1的母体来源和/或胚胎来源，AS 需要分析Smchd1 Earl函数。这项提案将提供有关 这些基因敲除动物的表型，以便进行更深入的机制研究。在目标1中，我们 将决定卵母细胞特异性基因敲除对卵子发生和早期胚胎活力的影响。在《目标2》中我们将 评估Smchd1‘S在控制基因表达前两波中被激活的基因中的作用 在2-细胞期。总体而言，这个项目寻求解决长期存在的基本谜团，即 哺乳动物的胚胎变得能够生存。

In mammals, the ability to regulate transcription is absent at the start of life. This fundamental ability is acquired during early cleavage stages through the formation of a transcriptionally repressive chromatin state (TRCS), wherein transcriptional enhancers first become necessary. Establishing the TRCS soon after fertilization is vital for two reasons: 1) it is important to suppress activation of endogenous transposable elements, which if activated can be mutagenic, and 2) it is essential to correctly execute the correct transcriptional program for embryo viability. This includes activating and repressing thousands of genes during four successive waves of embryonic genome activation (EGA1 to 4). Failure to establish the TRCS and to regulate EGA waves correctly kills embryos. We discovered that Structural maintenance of chromosomes flexible hinge domain containing protein one (SMCHD1) is a maternal effect gene that potentially orchestrates all of these events. SMCHD1 1) promotes EGA1 termination, 2) is implicated in repressing genes that are up-regulated during EGA2 to 4, and 3) supports inner cell mass (ICM) formation and embryo viability revealing long-term impacts of early SMCHD1 actions. Our overall model is that oocyte-expressed SMCHD1 terminates EGA1 and helps to establish the TRCS to allow correct gene regulation during EGA2. Embryo-expressed SMCHD1 then maintains and extends gene repression and enables optimum control of EGA3 & EGA4 necessary for embryo viability. The study of SMCHD1 mechanisms of action thus provides an important new entry for discovering fundamental mechanisms regulating embryonic genome function and viability. We created a novel floxed Smchd1 allele, which can be used to achieve oocyte-specific ablation of SMCHD1 function, and thus create embryos that lack maternal, embryonic or both sources of SMCHD1, as needed to dissect SMCHD1 earl functions. This proposal will provide essential preliminary data on the phenotype of these knockout animals to allow more in-depth mechanistic studies to be pursued. In Aim 1 we will determine the effects of oocyte-specific knockout on oogenesis and early embryo viability. In Aim 2 we will assess SMCHD1’s role in controlling genes that are activated during the first two waves of gene expression during the 2-cell stage. Overall, this project seeks to solve long-standing fundamental mysteries of how mammalian embryos become competent for life.