（CGG:GCC）短重复序列结合蛋白的大规模筛选和功能研究

近年研究发现，基因组非编码序列中的短重复序列（微卫星序列）不仅是染色体某些特殊结构的组成部分（如端粒），有些对基因转录调控也具有重要作用。（CGG:GCC）三联短重复序列显著性出现在基因翻译起始位点附近，且与所在区域的甲基化水平呈正相关；在已知的遗传疾病中，脆性X综合症的发生与（CGG:GCC）三联短重复序列的拷贝数扩张具有密切关系。由于生命活动过程一般通过复杂的核酸和蛋白网络相互调控实现，本研究拟利用自主构建的CRIBID生物素标记系统在guide RNA指引下对特定短重复序列的结合蛋白进行标记，并采用IP-MS大规模鉴定筛选特定短重复序列的结合蛋白，并深入研究其参与转录调控的生物学机制。在此基础上本研究还将从鉴定获得重要的结合蛋白出发，利用蛋白-蛋白相互作用筛选建立可以与这些短重复序列相互结合的蛋白调控网络，更全面地研究和阐述这些蛋白复合体如何与短重复序列共同作用发挥其生物学功能。

Recent research found that genomic simple sequence repeat(SSR, also called microsatellite) is not only the structural component (such as telomere) but also functions as regulator of gene transcription. (CGG:GCC) trimer locates typically abound gene transcription start sites(TSS) and has positive corelation with nearby DNA methylation. Among known hereditary diseases, the occurrance of fragile X syndrome is highly related to the copy number invasion of (CGG:GCC) trimer. Because biological process is basically achieved by sophisticated network of nucleic acids and proteins, this study aims to independently construct CRIBID screening system to label target SSR binding protein by biotin under the guidance of gRNA, and identify the binding proteins by IP-MS. Then the followed study will target on the mechanism study how these candidate proteins take part in transcription regulation. Further more this study will also use these functinonal candidates as baits to screening interacting protein complexes based on protein-protein interaction methods, aiming to demostrate the way that the nucleic acid-protein complex act together as biological regulator.