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.

生殖细胞性认同的保存对于繁殖至关重要。性别特定程序的缺陷导致不育症和生殖细胞肿瘤。尽管它对人类健康的重要性，但生殖细胞的性认同如何维护是未知的。果蝇雌性种系是研究这种重要的理想模型保持细胞命运的决定。保持性身份的失败之间的联系，异常精子发生基因和生殖细胞肿瘤发育的表达使基因可以分配给A 性命运维护途径。这些新研究表明，一种表观遗传调节途径 SXL是上游女性特异性调节剂，SetDB1是所需的染色质作者，PHF7是其中之一关键下游SETDB1目标基因保持性认同。 setDB1三甲基盐H3K9（H3K9me3），一个与基因沉默相关的组蛋白修饰。证据表明SXL的假设依赖的转录因子将SETDB1直接置于其精子发生靶基因，并沉积局部 H3K9me3标记，导致HP1A依赖性沉默。该途径的破坏导致异位PHF7 表达。该睾丸特异性蛋白足以重新编程其靶基因（包括本身），导致精子发生基因激活和生殖细胞肿瘤。该提案中的研究将测试这种模型并提高了我们对这一新确定的途径的理解，这是两个目标。在AIM 1中，重点是在setDB1上。 SETDB1通过安装基因特异性的假设沉默了精子发生基因将染色质沉默的靶基因将通过比较全球级别测试野生型和setDB1中的H3K9me3及其配体HP1A耗尽生殖细胞。这是一个关键问题假设是将SETDB1募集到其精子发生靶基因的方式。遗传研究已经确定两个可能是关键靶向因素的依赖性转录因子。结合遗传，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维护。在AIM 2中，重点是PHF7。 PHF7是一种结合的染色质读取器对于H3K4ME2，这是与活性或固定基因相关的标记。因此，异位PHF7可以重新编程性命运通过激活静音但固执的精子发生基因和/或通过抑制所需的活性基因精子发生基因沉默。测试此模型需要鉴定PHF7靶基因。我们将首先基于证据表明PHF7重新编程了自己的转录，然后采取更全球的方法。这些研究将导致对强迫表达如何破坏女性命运的理解，并将作为一个为这一新颖途径分配新基因的发现工具。生殖细胞生物学的惊人相似之处在人类和苍蝇之间表明，本提案中的研究所获得的知识将提供深入了解人类生殖细胞如何维持其性别身份，以及此过程中的错误如何干扰生殖。