小分子RNA介导的基因沉默协同调控泛素化蛋白降解的机制研究

During development, the cell identity is determined by its specific patterns of gene expression, which are controlled by multiple lawyers of regulatory mechanisms in a spatio-temporal manner. Among them, the microRNA-mediated post-transcriptional silencing and ubiquitin-mediated protein degradation are two distinct processes but both key for maintaining the proper gene expression. However, little is known about whether and how these two processes are coordinated to respond to the developmental and environmental cues. The Drosophila provides an excellent model that allows us to address this fundamental question in the fields of molecular and developmental biology. We have previously shown that both Ago1-mediated microRNA pathway and ubiquitin-mediated protein pathway are involved in germline stem cell maintenance. We recently find that Ago1 physically interacts with Ter94, a key regulator in the protein ubiquitination pathway, and our preliminary findings suggest that loss of ter94 enhances the activity of Ago1-associated RISC, highlighting a functional link between two pathways. In this proposal, we will use Drosophila as a model system, and employ the powerful genetic tool of flies integrated with molecular biology and biochemical methods to identify and characterize the novel genes and network involved in controlling coordination between microRNA-mediated gene silencing and ubiquitin-mediated protein degradation pathways. We believe that these knowledge and concepts obtained from fly will not only greatly promote our understanding how cells employ these processes to respond to the developmental and environmental cues, but also bring new insights into developing novel strategies in future medicine, as well as other therapeutic approaches to treat human diseases.

从受精卵到个体发育过程，基因表达受到严格的调控，基因表达调控涉及诸多环节。microRNA介导的转录后沉默和泛素介导的蛋白降解途径是基因表达过程两个重要的环节，但二者是否存在协同调控机制一直是分子生物学和发育生物学等领域关注的基本科学问题之一。我们实验室以果蝇为模型，对这一问题进行了探索。我们初步研究结果发现Ago1和Ter94功能上存在相互作用，表明microRNA途径和泛素介导的蛋白降解途径的确存在协同调控。本项目应对重大研究计划“非编码RNA与其他重要生物分子的相互作用、网络及其结构基础。”研究方向，以果蝇为模型，通过分子生物学、生物化学和遗传学相结合的手段，研究microRNA途径和泛素介导的蛋白降解途径如何在细胞中有序、高效地进行协同作用，并解析这种协同关系的分子机制。鉴于小分子RNA和Ter94在发育中的作用及与人类疾病的相关性，本项目的开展将为临床研究提供线索。

从受精卵到个体的发育过程中，基因表达受到严格的调控，基因表达调控涉及诸多环节。其中microRNA介导的转录后沉默和泛素介导的蛋白降解途径是基因表达过程中两个重要的调控方式，但二者是否存在协同调控机制一直是分子生物学和发育生物学等领域关注的基本科学问题之一。我们实验室以果蝇为模型，对这一问题进行探索，我们发现：1）miRNA介导的基因沉默与Ter94参与的翻译后调控之间的偶联关系；2）去泛素化酶Otu通过控制肠道免疫水平来调节果蝇寿命；3）膜定位的 inhibitory Smads通过棕榈酰化修饰调节TGF-β/BMP信号通路；4）Bam／Otu去泛素化功能复合物通过调控Cyclin A决定果蝇生殖干细胞命运；5）在果蝇早期胚胎中FMR1蛋白优先结合含有m6A修饰的RNA。这些发现有助于我们对microRNA介导的转录后沉默和泛素介导的蛋白降解途径两者协同调控机制的理解。