果蝇组蛋白H3K56调控卵巢发育的作用机制研究

Histones are not only the major structural proteins of eukaryotic chromatin, but also the regulatory factors of its function. Post-translational modifications on histones are involved in a variety of physiological processes including transcription, chromatin condensation and DNA damage repair. Perturbations in histone modification can lead to developmental disorders and sometimes development of cancers. Directly investigation of histone PTMs by mutagenesis has been extremely difficult because histone genes are normally present as multiple copies. To overcome this problem, we developed an efficient histone-mutagenesis platform and generated a library of H3 and H4 alanine-substitution mutants recently. We found that male fertility was slightly decreased for H3K56A, but the female flies was completely sterile with ovarian dysplasia, which suggested an important role of H3K56 in oogenesis in Drosophila. In this proposal, we will focus on the role of H3K56, the main functional PTM-type of H3K56, and the key factor regulated by H3K56 during oogenesis to investigate the mechanism of H3K56 during oogenesis in Drosophila. The completion of this project will provide direct evidence of histone proteins (and its post-translational modifications) in regulating reproductive organ development and aid understanding of related human diseases.

真核生物组蛋白是染色体的主要结构蛋白，也是染色体功能的重要调控因子。组蛋白翻译后修饰参与基因转录调控、染色质浓缩、DNA损伤修复等多种生理过程，组蛋白修饰缺陷可导致发育异常和多种癌症。组蛋白基因的多拷贝特点使得组蛋白点突变体的模型构建极其困难，已有研究主要局限于低等单细胞生物。课题组前期在模式生物果蝇中建立了高效的组蛋白突变体构建和分析平台，发现H3K56A突变导致雄蝇生育能力下降，雌蝇完全不育且卵巢发育不良，表明该位点对生殖发育有重要调控作用。本课题将通过免疫荧光染色、RNA-seq以及遗传分析等技术研究H3K56位点对果蝇卵巢发育过程的影响、解析对果蝇卵巢发育具有调控作用的翻译后修饰以及揭示H3K56位点调控的卵巢发育的关键因子，从而阐明H3K56位点调控果蝇卵巢发育的分子机制。本项目的完成将获得组蛋白及其翻译后修饰与生殖器官发育调控的直接证据，为人类相关遗传疾病的机制解析提供参考。

DNA缠绕在组蛋白上形成了真核生物的染色体，同时组蛋白也参与染色体的功能调控。为了研究位于DNA与组蛋白交界处的H3K56位点的生理功能，我们构建了H3K56A/Q/R突变体果蝇，并解析了H3K56通过调控卵巢生殖干细胞的微环境来调控生殖干细胞的维持和分化的机制。通过RNA-seq和ATAC-seq分析，我们发现在果蝇卵巢中H3K56参与调控染色体的“松-紧”状态从而影响基因的转录。本项目在多细胞生物果蝇中研究了组蛋白H3K56调控卵巢干细胞的维持和分化的机制，为组蛋白参与生殖调控提供了直接证据，为相关疾病的机制解析提供了参考。