G-Quadruplex-Based Chemical Genetics

通过小分子靶向DNA和RNA是干扰和研究癌症相关生物学最成功的策略之一。核酸可以采用非规范结构来调控对细胞稳定至关重要的生物过程，如基因调控和蛋白质表达。因此，许多研究都集中在开发对DNA和RNA二级结构具有选择性识别性能的分子。被称为G-四联体的核酸二级结构已经成为基因和蛋白质调节的候选结构。靶向和稳定存在于一些小分子基因中的G-四链会导致基因表达的变化。在整个基因组中发现了大量的G-四联体，这表明这些结构可能参与了无数的生物过程。尽管有大量已公开的配体选择性地识别典型的双链DNA上的G-四链，但它们都不能选择性地识别基因组中存在的一个特定的G-四链。因此，具有对特定结构的选择性的配体将提供仅干扰与靶结构相关的生物功能的手段。我们最近开发了一种新的方法来在靶向G-四链存在的情况下原位产生分子，产生靶向结构的特异性配体。当在靶核酸(即特定的DNA或RNAG-四链)存在的情况下进行化学连接时，只有那些与目标特定相互作用的官能团才会引起连接并产生加合物。通过这种方法产生的分子将对目标具有极高的选择性，因为它们将拥有与其相互作用的完美几何结构。通过发展这种方法，我们已经证明了有可能产生对DNA G-四链上的RNA具有选择性的分子。我们现在希望进一步开发和推广这种方法，增加可能加合物的复杂性和可变性，以使高度特异的配体的形成成为可能。这种方法产生的化学工具将进一步深入了解G-四联体在不同基因组位置形成的机制。我们的最终目标是通过使用小分子来实现选择性的基因调控，这些小分子只针对存在于给定基因组区域的G-四链。

Targeting DNA and RNA by means of small molecules is one the most successful strategies to interfere with and study cancer related biology. Nucleic acids can adopt non-canonical structures that have been suggested to regulate biological processes crucial for cellular stability, such as gene regulation and protein expression. Therefore many studies have focussed on the development of molecules with selective recognition properties towards DNA and RNA secondary structures. Nucleic acid secondary structures named G-quadruplexes have emerged as candidates for gene and protein regulation. Targeting and stabilising the G-quadruplexes present in some genes with small molecules leads to an alteration in the gene expression. A large number of G-quadruplexes have been found in the whole genome, suggesting that these structures can be involved in a myriad of biological processes. Despite the large number of disclosed ligands that selectively recognize G-quadruplexes over the canonical double stranded DNA, none of them is able to selectively recognize one particular G-quadruplex over the others present in the genome. Therefore, having a ligand selective for one particular structure will provide the means to interfere only with the biological functions associated with the targeted structure. We recently developed a new method to generate molecules "in situ" in the presence of the targeted G-quadruplex, generating ligands specific for the targeted structure. When running a chemical ligation in the presence of a targeted nucleic acid (i.e a specific DNA or RNA G-quadruplex) only those functionalities that specifically interact with the target will give rise to the ligation and generate an adduct. The molecules generated by this method will be extremely selective for the target, as they will posses the perfect geometry to interact with it. By developing this method we have already demonstrated that is possible to generate molecules that are selective towards RNA over DNA G-quadruplexes. We now want to further develop and extend this method increasing the complexity and the variability of the possible adducts to enable the formation of highly specific ligands. The chemical tools generated by this method will provide further insights into the mechanism behind G-quadruplex formation in different genomic locations. Our final goal is to achieve selective gene regulation by using small molecules that target only the G-quadruplexes present in a given genomic region.