G-Quadruplexes as Targets for Drug Design

某些DNA序列具有形成DNA二级结构的能力，所述二级结构具有与双链体DNA完全不同的分子识别特征。 特别是，我们对一组称为G-四链体或DNA四链体的四链结构感兴趣。 用于形成G-四链体的基序在真核基因组中似乎是罕见的，但在具有生物学意义的区域中发现（例如，端粒和启动子区）。 我们已经鉴定了靶向这些序列并影响G-四链体的形成和解旋速率的小分子。 在这个建议中，我描述的实验，将确定这些小分子的作用，G-四链体在开关机制中发挥的作用，在调节区的癌基因和稳定的端粒区的T-环。 G-四链体在重组中的其他可能作用及其在体内的存在也将被评估。 生物物理方法，包括NMR和PAGE，将主要用于本研究。该建议的具体目的是（1）确定导致G-四链体和i-基序相互作用化合物下调c-myc的分子机制;（2）确定t-环侵入复合物的分子结构并将其用作开发新的端粒相互作用化合物的指导;（3）确定G-四链体相互作用化合物对其他蛋白质-G-四链体复合物的影响，包括拓扑异构酶I-G-四链体DNA;（4）利用LM-PCR技术检测体内G-四链体结构的存在。

Certain DNA sequences have the capability to form DNA secondary structures that have molecular recognition features quite distinct to duplex DNA. In particular, we are interested in a group of four-stranded structures called G-quadruplexes or DNA tetraplexes. Motifs for the formation of G-quadruplexes appear to be rare in the eukaryotic genome but are found in regions of biological significance (e.g., telomeres and promoter regions). We have identified small molecules that target these sequences and affect the rate of formation and unwinding of G- quadruplexes. In this proposal, I describe experiments that will determine the effect of these small molecules on the role that G- quadruplexes play in switch mechanisms in regulatory regions of oncogenes and in stabilizing t-loops in telomeric regions. Other possible roles of G-quadruplexes in recombination and their in vivo existence will also be evaluated. Biophysical methods, including NMR and PAGE, will be used primarily in this study. The specific aims of this proposal are to (1) determine the molecular mechanism that results in the down- regulation of c-myc by G-quadruplex and i-motif-interactive compounds; (2) determine the molecular structure of the t-loop invasion complex and use this as a guide to develop new telomere- interactive compounds; (3) determine the effect of G-quadruplex-interactive compounds on other protein-G-quadruplex complexes, including the topoisomerase I-G-quadruplex DNA; (4) use LM-PCR to probe for the occurrence of G-quadruplex structures in vivo.