Molecular and genetic analysis of meiotic silencing in C. elegans

本项目的总体目标是了解维持生殖系完整性和确保功能配子产生的分子机制。 这项研究特别关注线虫中未配对（未突触）DNA的减数分裂沉默。 在动物和真菌的减数分裂过程中，未配对染色体上的基因表达受到抑制。 这种广泛保守的现象对于基因组防御、基因组完整性的维持和/或未配对染色体的分离以及种系发育可能是重要的。 In C.在线虫中（如在更复杂的动物中），未配对的DNA在染色质水平被抑制。 这种抑制的一个标志是与转录沉默相关的组蛋白修饰的积累，组蛋白H3在赖氨酸9上的二甲基化（H3 K9 me 2）。 缅因州博士的实验室探索了C.并发现它需要EGO-1，一种假定的RNA指导的RNA聚合酶（RdRP）。 他们使用基因表达谱和其他方法来鉴定在ego-1突变生殖系中升高的转录本，并预测EGO-1染色质调节的靶点在这些基因中。 缅因州实验室还表明，EGO-1是生殖细胞发育的许多方面所必需的，并最终影响生育能力。 总之，这些结果表明，减数分裂沉默可能具有发育功能。 基于这些数据，缅因州博士和她的同事们提出了两种替代模型，用于解释H3 K9 me 2在未配对DNA上的积累机制。 在这个项目中，将测试这些模型的具体预测。 在目标1中，将使用候选基因方法来鉴定减数分裂沉默机制的其他组分。 在目标2中，将使用遗传筛选来恢复减数分裂沉默组分中的突变。 这种无偏见的方法补充了目标1，并将允许恢复可能预计不会在减数分裂沉默中发挥作用的基因突变。 在目标3中，将鉴定EGO-1介导的沉默的靶点。该项目将提供对理解生物学的几个领域至关重要的信息，包括生殖生物学（以及最终的生育力）。 在过去的8-10年里，生物学家发现RNA分子参与调节细胞中蛋白质产生的过程。 在这个项目中，研究人员将研究一种新发现的转录调控机制，这种机制在配子（精子和卵子）形成过程中使用。 此外，调查员将充分整合她的研究到她的教学和指导研究生和本科生。

The overall goal of this project is to understand the molecular mechanisms that maintain germline integrity and ensure the production of functional gametes. The research specifically focuses on meiotic silencing of unpaired (unsynapsed) DNA in the nematode, Caenorhabditis elegans. During meiosis in animals and fungi, the expression of genes on unpaired chromosomes is repressed. This broadly conserved phenomenon may be important for genome defense, maintenance of genome integrity, and/or segregation of unpaired chromosomes, as well as germline development. In C. elegans (as in more complex animals), unpaired DNA is repressed at the chromatin level. One hallmark of this repression is the accumulation of a histone modification associated with transcriptional silencing, dimethylation of histone H3 on lysine 9 (H3K9me2). Dr. Maine's laboratory has explored the mechanism of H3K9me2 accumulation during meiosis in C. elegans and found that it requires EGO-1, a putative RNA-directed RNA polymerase (RdRP). They have used gene expression profiling and other approaches to identify transcripts that are elevated in the ego-1 mutant germ line, and predict that targets of EGO-1 chromatin regulation are among these genes. The Maine laboratory has also shown that EGO-1 is required for many aspects of germline development and, ultimately, for fertility. Taken together, these results suggest that meiotic silencing may have a developmental function. Based on the data, Dr. Maine and her colleagues proposed two alternative models for the mechanism of H3K9me2 accumulation on unpaired DNA. In this project, specific predictions of these models will be tested. In Objective 1, a candidate gene approach will be used to identify additional components of the meiotic silencing machinery. In Objective 2, genetic screens will be used to recover mutations in meiotic silencing components. This unbiased approach complements Objective 1 and will allow the recovery of mutations in genes that might not be predicted to function in meiotic silencing. In Objective 3, targets of EGO-1-mediated silencing will be identified. This project will provide information that is critical for understanding several areas of biology, including reproductive biology (and ultimately, fertility). In the last 8-10 years, biologists have discovered that RNA molecules participate in processes that regulate protein production in cells. In this project the investigator will study a newly identified mechanism of transcriptional regulation that is used during the formation of gametes (sperm and eggs). Furthermore, the investigator will fully integrate her research into her teaching and mentoring of both graduate and undergraduate students.