Functions of a newly identified meiotic protein, SCML1, and a meiosis-specific nuclear structure, the dense-body, in mice

新发现的减数分裂蛋白 SCML1 和减数分裂特异性核结构（致密体）在小鼠中的功能

• 批准号: 240457056
• 负责人: Professor Dr. Attila Tóth
• 金额: --
• 依托单位: Institut für Physiologische Chemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2013
• 资助国家: 德国
• 起止时间: 2012-12-31 至 2016-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/240457056?language=en
• 关键词: Functions; newly; identified; meiotic; protein

Meiosis produces haploid gametes from diploid germ cells, thereby providing the basis for sexual reproduction in mammals. Generation of haploid gametes depends on meiosis-specific features of chromosome behaviour and regulation of protein expression. To gain novel insights into the molecular basis of haploid gamete generation, we screened for meiotic proteins with a potential role in essential meiosis-specific processes. Among others, our screen discovered a novel meiotic protein, which we identified as the previously unrecognized mouse orthologue of human SCML1, a protein of unknown function. Mouse SCML1 is a component of a meiosis-specific RNA-rich nuclear structure, the dense-body (DB). DBs form during the first meiotic prophase in mammals, including humans. Although the composition and the functions of the DB remain enigmatic, recent discoveries indicate possible functions for DBs in crucial aspects of meiosis, such as small non-coding RNA (smRNA) biology and meiotic sex chromosome silencing in spermatocytes.Our results show that ectopically expressed SCML1 builds DB-like structures in somatic cells, indicating that SCML1 might be a structural component of DBs. Therefore, we propose to address the functions of the meiotic DB through the analysis of SCML1. We will investigate the functions of SCML1 by analysing meiosis and gametogenesis in Scml1 knockout mice, which will be generated from our recently produced mouse-strain that carries a conditional knockout Scml1 allele. In particular, we will address putative roles of SCML1 in meiotic smRNA metabolism and/or in transposon silencing and sex chromosome silencing. The latter two are essential meiotic processes that have been linked to meiotic smRNA biology. Furthermore, we plan to purify DBs/SCML1 containing RNA-protein complexes, to identify and characterize proteins and RNA species that accumulate in DBs. This will be relevant for understanding the role of DBs in meiotic RNA biology. As part of these experiments, we will compare the RNA composition of SCML1 containing RNA-protein complexes in wildtype and in meiotic mutants that display abnormalities in smRNA metabolism (e.g.: Mili and Miwi mutants). In addition, we will use yeast-two hybrid and biochemical approaches to identify and characterize SCML1 protein interactions and to examine the molecular basis of SCML1-mediated formation of DB-like structures.I expect that these experiments will reveal SCML1 and DB functions in meiosis, and will allow us to better understand the mechanistic role of DBs in meiotic smRNA biology and related processes. These experiments will also likely impact on our understanding of human reproductive health, since smRNAs are believed to safeguard the germline from transposons and play essential roles during gametogenesis.

减数分裂从二倍体生殖细胞产生单倍体配子，从而为哺乳动物的有性繁殖提供基础。单倍体配子的产生取决于减数分裂特有的染色体行为特征和蛋白质表达的调节。为了获得对单倍体配子产生的分子基础的新见解，我们筛选了在基本减数分裂特定过程中具有潜在作用的减数分裂蛋白。其中，我们的筛查发现了一种新的减数分裂蛋白，我们确定它是以前未被识别的人类SCML1的小鼠同源蛋白，一种功能未知的蛋白。小鼠SCML1是减数分裂特有的富含RNA的核结构致密体(DB)的组成部分。DBS在哺乳动物包括人类的第一次减数分裂前期形成。尽管DB的组成和功能仍然是个谜，但最近的发现表明DBs可能在减数分裂的关键方面发挥功能，如小分子非编码RNA(SmRNA)生物学和精子细胞中减数分裂的性染色体沉默。我们的结果表明，异位表达的SCML1在体细胞中建立了类似DB的结构，表明SCML1可能是DBs的结构成分。因此，我们建议通过对SCML1的分析来研究减数分裂DB的功能。我们将通过分析Scml1基因敲除小鼠的减数分裂和配子发生来研究SCML1的功能，这将来自我们最近培育的携带条件基因敲除Scml1等位基因的小鼠品系。特别是，我们将讨论SCML1在减数分裂smRNA代谢和/或转座子沉默和性染色体沉默中的可能作用。后两个过程是与减数分裂smRNA生物学相关的基本减数分裂过程。此外，我们计划提纯含有DBs/SCML1的RNA-蛋白质复合体，以鉴定和表征DBs中积累的蛋白质和RNA物种。这对于理解dbs在减数分裂RNA生物学中的作用是相关的。作为这些实验的一部分，我们将比较野生型和显示smRNA代谢异常的减数分裂突变体(例如：mili和miwi突变体)中包含RNA-蛋白质复合体的SCML1的RNA组成。此外，我们将使用酵母-两种杂交和生化方法来鉴定和表征SCML1蛋白的相互作用，并研究SCML1介导的类DB结构形成的分子基础。我希望这些实验将揭示SCML1和DB在减数分裂中的功能，并将使我们更好地理解DBs在减数分裂smRNA生物学和相关过程中的机制作用。这些实验也可能影响我们对人类生殖健康的理解，因为smRNAs被认为可以保护生殖系免受转座子的影响，并在配子发生过程中发挥重要作用。