Mechanism of transcriptional gene silencing induced by convergent transcription in human cells and its application in breast cancer.

所有生物体都是由通过细胞分裂繁殖的细胞组成的。定义每种细胞类型的遗传密码储存在DNA分子中。DNA包含被称为基因的编码区域。基因被转录成信使RNA （mRNA）分子，而信使RNA分子又被翻译成蛋白质，这个过程被称为基因表达。重要的是，每个细胞制造适当水平的蛋白质，这是通过控制基因表达来实现的。不受控制的基因表达会导致癌症或细胞死亡。基因沉默是调控基因表达最重要的机制之一。人类细胞中的基因沉默需要小RNA分子（siRNA）的存在，它可以激活RNAi途径。这导致细胞质中靶mRNA的识别和破坏。另一种类型的基因沉默是在DNA上建立特异性修饰，从而导致基因转录抑制，也称为转录基因沉默（transcriptional gene silencing， TGS）。人们对TGS在人类中的作用机制知之甚少。本奖学金申请中提出的工作将利用来自其他生物的关于TGS的现有知识来调查和探索人类如何诱导TGS以及通过何种机制诱导TGS的细节。这项工作具有重要意义，因为它可以导致开发具有巨大治疗应用潜力的新研究工具。

All organisms consist of cells that multiply through cell division. The genetic code, which defines each cell type, is stored within DNA molecules. DNA contains coding regions called genes. Genes are transcribed into messenger RNA (mRNA) molecules, which are in turn translated into proteins, a process called gene expression. It is important that each cell makes the right levels of proteins, which is achieved by controlled gene expression. Uncontrolled gene expression can lead to cancer or cell death. One of the most important mechanisms for the regulation of gene expression is gene silencing. Gene silencing in human cells requires the presence of small RNA molecules (siRNA), which activate the RNAi pathway. This leads to recognition and distruction of target mRNA in the cytoplasm. Another type of gene silencing is the establishment of specific modifications on DNA, which leads to inhibition of gene transcription, also called transcriptional gene silencing (TGS). Little is understood about the mechanism of TGS in humans. The work proposed in this fellowship application will use available knowledge about TGS from other organisms to investigate and explore the details of how TGS can be induced in humans and by what mechanism. This work has important implications given that it can lead to development of new research tools with a great potential for therapeutic application.