Basonuclin and Ribosome Biogenesis in Mouse Oocyte and Embryo

小鼠卵母细胞和胚胎中的基底核蛋白和核糖体生物发生

• 批准号: 7760658
• 负责人: RICHARD M SCHULTZ
• 金额: $ 23.39万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-02-01 至 2012-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7760658
• 关键词: Affect; Animal Model; Area; Assisted Reproductive Technology; Biogenesis; Biology; Cloning; DNA Polymerase I; Data; Dependency; Development; Embryo; Embryonic Development; Equilibrium; Excision; Failure; Foundations; Future; Genes; Genetic Transcription; Genetic Translation; Genome; Heterogeneity; Human; Immunoglobulin Variable Region; Infertility; Investigation; Knockout Mice; Lead; Mammals; Maps; Maternal Messenger RNA; Mediating; Messenger RNA; Mus; Oocytes; Oogenesis; Pattern; Population; Population Heterogeneity; Reagent; Recombinant DNA; Regulation; Research Infrastructure; Ribosomal Proteins; Ribosomal RNA; Ribosomes; Role; Sequence Alignment; Signal Transduction; Staging; Structure; Techniques; Testing; Tissues; Translating; Translations; Variant; Woman; Zinc Fingers; base; basonuclin; cell type; egg; embryo cell; improved; interest; knock-down; null mutation; oocyte maturation; preimplantation; programs; public health relevance; rRNA Genes; transcription factor

DESCRIPTION (provided by applicant): An important component of the mammalian maternal store is ribosome. Translation of maternal mRNA in early embryo depends on the maternal ribosomes. However, a large portion of the maternal ribosomes is destroyed along with many other mRNAs during oocyte maturation. This programmed destruction of maternal ribosomes has been most perplexing and appears wasteful. From the prevailing view in ribosome biology, there is only one type of ribosome and why cannot early embryos use these ribosomes that are destroyed during oocyte maturation? Our recent results suggest an unconventional explanation to this dilemma. Based on these results, we hypothesize that oocytes transcribe several types of rRNA, some of which are used for oogenesis, whereas others for translating maternal mRNA in early embryos. We showed recently that basonuclin (BNC1, Bnc1), a cell-type specific transcription factor for the ribosomal RNA genes (rDNA), is also a mammalian maternal effect gene. Furthermore, our data suggest that BNC1 regulates a subset of rDNA. This observation led us to isolate seven subtypes of variant rDNA (v-rDNA). Subsequent characterization of these v-rDNAs showed that each variant is regulated independently and tissue-specifically. Taken together, these results suggest that perturbation of expression of a subset of rRNA in oocytes may lead to embryonic developmental failure. Our hypothesis challenges the prevailing notion that rDNA transcription units are homogeneous and regulated uniformly in all tissues. Therefore, our hypothesis, if correct, will revise current understanding of ribosomal biogenesis, especially its implication in oogenesis and early embryogenesis. To test this hypothesis, we propose two Specific Aims. Specific Aim 1 will determine if rRNA population is heterogeneous by cloning and examining the rRNA region (i.e., cytoplasmically expressed region) of each v-rDNA. Using multiple sequence alignment, this investigation will determine if variable regions (markers) exist among rRNAs, which indicate rRNA heterogeneity. Specific Aim 2 will investigate if mouse oocytes contain several different types of rRNA and whether some are selectively degraded during oocyte maturation. We will use markers identi- fied previously and in Aim 1 to examine the expression of each v-rDNA/rRNA subtypes in oo- cytes and early embryos. Using our BNC1-deficiency oocytes, we will investigate if loss of BNC1 perturbs the balance of v-rDNA expression in the maternal store. These studies will pro- vide experimental foundations for hypotheses to be tested in the ensuing R01 application. PUBLIC HEALTH RELEVANCE: Recent studies suggest that eggs of "low quality" are largely responsible for infertility in women, and yet what constitutes a "good egg"-of which the maternal store is an integral part-is unknown. The proposed studies will increase our basic understanding of what constitutes a "good egg". Specifically, we will examine if the maternal store of rRNA is heterogeneous and how this heterogeneity influences early embryonic development. Such information may ultimately translate to improving the practice of Assisted Reproductive Technology (ART).

描述（由申请人提供）：哺乳动物母体商店的重要组成部分是核糖体。早期胚胎中母体mRNA的翻译取决于母体核糖体。但是，在卵母细胞成熟期间，很大一部分母体核糖体与许多其他mRNA一起破坏。这种编程的孕产妇核糖体的破坏最令人困惑，而且看起来很浪费。从核糖体生物学的普遍观点来看，只有一种核糖体，为什么早期胚胎不能使用这些在卵母细胞成熟过程中破坏的核糖体？我们最近的结果表明对这一困境有一个非常规的解释。基于这些结果，我们假设卵母细胞转录几种类型的rRNA，其中一些用于卵子发生，而另一些则用于在早期胚胎中翻译母体mRNA。我们最近表明，Basonuclin（BNC1，BNC1）是核糖体RNA基因（RDNA）的细胞类型特异性转录因子（RDNA）也是哺乳动物母体效应基因。此外，我们的数据表明BNC1调节了RDNA的子集。该观察结果使我们分离了七个变体rDNA（V-RDNA）的亚型。这些V-RDNA的随后表征表明，每个变体都受到独立和组织的调节。综上所述，这些结果表明，卵母细胞中RRNA子集表达的扰动可能导致胚胎发育衰竭。我们的假设挑战了普遍的观念，即rDNA转录单元在所有组织中都是均匀的，并且在所有组织中都均匀调节。因此，如果正确的话，我们的假设将修改当前对核糖体生物发生的理解，尤其是其在卵子发生和早期胚胎发生中的意义。为了检验这一假设，我们提出了两个具体目标。特定的目标1将通过克隆和检查每个V-RDNA的rRNA区域（即细胞质表达的区域）来确定rRNA群体是否是异质的。使用多个序列比对，该研究将确定RRNA之间是否存在可变区域（标记），这表明RRNA异质性。特定的目标2将研究小鼠卵母细胞是否包含几种不同类型的rRNA，以及在卵母细胞成熟过程中是否有选择性降解。我们将使用以前识别的标记，并在AIM 1中检查卵子细胞和早期胚胎中每个V-RDNA/rRNA亚型的表达。使用我们的BNC1缺乏卵母细胞，我们将研究BNC1的损失是否会使母体存储中V-RDNA表达的平衡。这些研究将为在随后的R01应用中测试的假设提供实验基础。公共卫生相关性：最近的研究表明，“低品质”的卵在很大程度上是女性不孕症的原因，但是构成母体商店的“好鸡蛋”是一个不可或缺的部分。拟议的研究将增加我们对构成“好鸡蛋”的基本理解。具体而言，我们将检查rRNA的母体存储是否是异质的，以及这种异质性如何影响早期胚胎发育。这些信息最终可能转化为改善辅助生殖技术（ART）的实践。