飞蝗卵子发生期保幼激素调控细胞多倍化的分子机制

The migratory locust, Locusta migratoria is a evolutionarily primitive insect species with panoistic ovarioles. During oogenesis, the nutritional materials and signal molecules were mostly transferred from fat body to developing oocytes through hemolymphal circulation. Juvenile hormone (JH) promotes the polyploidization of fat body and follicle cells for vitellogenesis and oocyte maturation at this stage. However, the underlying molecular mechanism remains unclear. Successful cell polyploidy lies in two key aspects: DNA replication and cell division inhibition. In this project, 22 candidate genes were filterd by bioinformatic analysis of RNA-seq data and RNAi. These genes were JH-upregulated and involved in DNA replication and cell division. Here, we will use methods, such as luciferase assay, EMSA, metabolomics and proteinomics to gain three goals: (1) How JH regulates fat body cell polyploidy through binding with Met (2); How JH promotes fat body cell polyploidy through binding other transcriptional factors (3) Elucidating the molecular mechanism of follicle cell polyploidy by signal transfer among tissues. In all, we try to construct a regulatory network and elucidate the molecular mechanism of cell polyploidization governed by JH during oogenesis.

飞蝗是无滋式卵小管，其卵子发生所需营养物质基本都来源于脂肪体。脂肪体与卵巢之间通过血淋巴完成信号传递及营养输送。卵子发生期，保幼激素（JH）刺激脂肪体和卵泡细胞多倍化，进而促进卵黄发生和卵子成熟，但其分子机制未完全清楚。细胞多倍化在于两个关键方面：DNA大量复制和细胞分裂抑制。本项目一方面以基因表达谱和RNA干扰筛选到的22个受JH调高表达，并调控多倍化的基因做为研究对象，利用荧光素酶检测、电泳迁移率试验、亲和柱纯化和蛋白质谱等方法，探究（1）JH通过其受体Met如何调控脂肪体细胞多倍化（2）JH如何与其它转录因子作用，调控脂肪体细胞多倍化。另一方面，通过测定代谢组和蛋白质组，探究组织间分子信号如何通过血淋巴传递，决定卵泡细胞多倍化。最终初步构建出决定细胞多倍化的调控网络，阐明JH调控卵子发生期细胞多倍化的分子机制。

飞蝗是无滋式卵小管，其卵子发生所需营养物质基本都来源于脂肪体。脂肪体与卵巢之间通过血淋巴完成信号传递及营养输送。卵子发生期，保幼激素（JH）刺激脂肪体和卵泡细胞多倍化，进而促进卵黄发生和卵子成熟，但其分子机制未完全清楚。细胞多倍化在于两个关键方面：DNA大量复制和细胞分裂抑制。本项目以前期转录组发现的可能调控多倍化的基因为研究对象，阐明了保幼激素可以通过其受体直接调控Cdc6基因表达，促进细胞多倍化的过程；阐明了保幼激素可以直接调控Cdk6和E2f1的表达，抑制细胞分裂，促进细胞多倍化过程；揭示了两种脂肪体在蝗虫中的组织分化，及其分化对于生殖功能的作用；并对于前面的研究进行了综述性回顾，结合其它昆虫中细胞多倍化的研究，提出了未来细胞多倍化的重要研究方向。这些研究共同阐明了昆虫多倍化的内分泌调控机制及其他调控模式。细胞多倍化对于生殖过程意义重大，通过对脂肪体和卵泡细胞多倍化机制的研究，一方面可以理解生殖调控的机制，另一方面为通过生殖调控控制害虫提供了靶标基因。