Sexual Identity Maintenance in Drosophila Female Germ Cells

果蝇雌性生殖细胞的性别认同维持

基本信息

批准号：
10241355
负责人：
HELEN Karen SALZ
金额：
$ 32.2万
依托单位：
CASE WESTERN RESERVE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2018
资助国家：
美国
起止时间：
2018-09-01 至 2023-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10241355
关键词：
Binding Cells Cellular biology Chromatin Cytology Data Defect Deposition Development Drosophila genus Epigenetic Process Failure Female Gametogenesis Gene Activation Gene Expression Regulation Gene Silencing Gene Targeting Genes Genetic Genetic Transcription Genetic study Genomic approach Germ Cells Germ cell tumor Health Heterochromatin Human Infertility Knowledge Lead Ligands Maintenance Mediating Modeling Organism Ovarian PHD Finger Pathway interactions Pattern Process Production Protein Binding Domain Proteins RNA Reader Regulatory Pathway Reproduction Reproductive Health SETDB1 gene Spermatogenesis Study models Testing Testis Translating Untranslated RNA Zinc Fingers base egg fly histone modification insight member mutant novel preservation programs promoter protein expression recruit sex sexual identity sperm cell tool transcription factor transcriptional reprogramming

项目摘要

The preservation of germ cell sexual identity is essential for reproduction. Defects in sex-specific programs leads to infertility and germ cell tumors. Despite its importance to human health, how germ cell sexual identity is maintained is unknown. The Drosophila female germline is an ideal model for studying how this important cell fate decision is maintained. The connection between failures to maintain sexual identity, aberrant expression of spermatogenesis genes and germ cell tumor development enabled the assignment of genes to a sex fate maintenance pathway. These new studies demonstrate that an epigenetic regulatory pathway in which SXL is the upstream female-specific regulator, SETDB1 is the required chromatin writer and phf7 is one of the key downstream SETDB1 target genes, maintains sexual identity. SETDB1 trimethylates H3K9 (H3K9me3), an histone modification associated with gene silencing. The evidence suggests a hypothesis in which Sxl dependent transcription factors direct SETDB1 to its spermatogenesis target genes, where it deposits a local H3K9me3 mark, leading to HP1a-dependent silencing. Disruption of this pathway leads to ectopic PHF7 expression. This testis-specific protein is sufficient to reprogram transcription of its target genes (including itself), leading to spermatogenesis gene activation and a germ cell tumor. The studies in this proposal will test this model and advance our understanding of this newly identified pathway, in two Aims. In Aim 1, the focus is on SETDB1. The hypothesis that SETDB1 silences spermatogenesis genes by installing gene specific silencing chromatin on its target genes will be tested at a global level by comparing the distribution of H3K9me3 and its ligand HP1a in wild-type and SETDB1 depleted germ cells. A key question raised by this hypothesis is how SETDB1 is recruited to its spermatogenesis target genes. Genetic studies have identified two Sxl dependent transcription factors that are likely to be the critical targeting factors. Combined genetic, cytological and genomic approaches will be used to determine how these newly identified pathway members contribute to female fate maintenance. In Aim 2, the focus is on PHF7. PHF7 is a chromatin reader that binds to H3K4me2, a mark associated with active or poised genes. Thus ectopic PHF7 may reprogram sexual fate by activating silent, but poised, spermatogenesis genes, and/or by repressing active genes required for spermatogenesis gene silencing. Testing this model requires identification of PHF7 target genes. We will first build on evidence that PHF7 reprograms its own transcription, and then take a more global approach. These studies will lead to an understanding of how forced expression is able to disrupt female fate, and will serve as a discovery tool for assigning new genes to this novel pathway. The striking similarities in germ cell biology between humans and flies suggest that the knowledge gained from the studies in this proposal will provide insight into how human germ cells maintain their sexual identity, and how errors in this process interferes with reproduction.

生殖细胞性别特征的保存对于繁殖至关重要。针对特定性别的计划存在缺陷导致不孕和生殖细胞肿瘤。尽管生殖细胞的性别认同对人类健康很重要，但它如何是否维持未知。果蝇雌性种系是研究这一重要性的理想模型。细胞命运决定得以维持。未能维持性别认同、异常之间的联系精子发生基因的表达和生殖细胞肿瘤的发展使得基因能够分配给性命运维持途径。这些新研究表明，表观遗传调控途径 SXL 是上游女性特异性调节因子，SETDB1 是所需的染色质编写器，phf7 是其中之一关键下游 SETDB1 目标基因，维持性别认同。 SETDB1 三甲基化 H3K9 (H3K9me3)，与基因沉默相关的组蛋白修饰。证据提出了一个假设，其中 Sxl 依赖性转录因子将 SETDB1 引导至其精子发生靶基因，并在那里沉积局部 H3K9me3 标记，导致 HP1a 依赖性沉默。该通路的破坏会导致异位 PHF7 表达。这种睾丸特异性蛋白质足以重新编程其靶基因的转录（包括本身），导致精子发生基因激活和生殖细胞肿瘤。本提案中的研究将测试这个模型并促进我们对这个新发现的途径的理解，有两个目标。在目标 1 中，重点是在 SETDB1 上。 SETDB1 通过安装基因特异性沉默精子发生基因的假设沉默其靶基因上的染色质将通过比较染色质的分布在全球范围内进行测试野生型和 SETDB1 耗尽的生殖细胞中的 H3K9me3 及其配体 HP1a。由此提出的一个关键问题假设是 SETDB1 如何被招募到其精子发生靶基因中。遗传学研究已确定两个 Sxl 依赖性转录因子可能是关键的靶向因子。结合遗传基因，细胞学和基因组方法将用于确定这些新鉴定的途径成员如何有助于女性命运的维持。在目标 2 中，重点是 PHF7。 PHF7 是一种染色质读取器，可结合 H3K4me2，与活跃或平衡基因相关的标记。因此异位PHF7可能会重新编程性命运通过激活沉默但蓄势待发的精子发生基因，和/或通过抑制精子发生所需的活性基因精子发生基因沉默。测试该模型需要鉴定 PHF7 靶基因。我们首先会基于 PHF7 重新编程其自身转录的证据，然后采取更全局的方法。这些研究将有助于了解强迫表达如何扰乱女性命运，并将作为用于将新基因分配给这一新途径的发现工具。生殖细胞生物学的惊人相似之处人类和苍蝇之间的关系表明，从本提案中的研究中获得的知识将提供深入了解人类生殖细胞如何保持其性别身份，以及此过程中的错误如何干扰生殖。