piRNA通路新成员CG4936在异染色质形成过程中的作用

转座子是基因组中可复制和转座的DNA序列，转座子的不恰当转座会威胁基因组的稳定，甚至会产生致死表型。piRNA通路是一个由小RNA介导的“天然免疫”系统，可以保护基因组抵御转座子的不恰当转座。Panx可以与Piwi/piRNA复合物结合，诱导转座子沉默并介导异染色质形成，但其中还需哪些因子的参与还需进行更深入的研究。本课题利用果蝇中Panx的拴住模型，通过正向RNAi筛选出了piRNA通路中的锌指蛋白CG4936。我们推测CG4936可能通过与绝缘子蛋白Ibf1结合而抑制转座子的表达进而调控异染色质的形成。我们拟利用RNA拴住模型系统研究：1)CG4936和转座子的动态表达模式；2)CG4936在异染色质形成过程中的作用；3)CG4936与绝缘子蛋白的相互作用模式；4)CG4936对三维基因组的影响。本项研究将阐明CG4936调控异染色质形成的分子机制，为不孕不育症的诱发机制提理论基础。

Transposons are DNA sequences that can move from one location to another in the genome. Improper translocation of transposons threatens the stability of the genome, or even cause lethal phenotype. Piwi-interacting RNA (piRNA) pathway is a small RNA based “innate immune” system that defends animal germline genomes against transposons. Panoramix (Panx), associated with Piwi/piRNA complex, is sufficient to induce transcriptional silencing and heterochromatin formation when tethered to nascent RNAs. But it is still a mystery whether other factors are involved in this pathway. Using Panx-tethering as a reporter system, we performed a RNAi screen and found a novel gene CG4936,which encodes a zinc figure protein, is required for transcriptional silencing. In this respect, CG4936 is likely to regulate the expression of transposons and subsequently mediates the formation of heterochromatin. Using RNA-tethering as a reporter system, we propose here to investigate：1) The spatiotemporal expression pattern of CG4936 and transposons;2) The role of CG4936 in heterochromatin formation; 3) The interaction between CG4936 and insulator protein Ibf; 4) The effect of CG4936 on 3D genome. This study will elucidate the role of CG4936 in formation of heterochromatin and provide theoretical basis for human infertility.