癌基因诱导的细胞衰老是当今衰老和癌症研究领域的一大热点。衰老相关的异染色质位点（SAHF）在癌基因诱导细胞衰老的发生和维持中极为重要。SAHF形成的分子机理及其对靶基因的选择性是当前癌基因诱导细胞衰老研究领域的两个重要问题。基于前期研究和最新的结果，我们提出：衰老细胞中存在BRG1-HP1-H3K9me复合物，它们是SAHF形成的核心元件。在本项目中，我们将验证BRG1-HP1-H3K9me复合物在衰老细胞中的存在，研究复合物的变化对SAHF形成的影响，搜寻其他可能与复合物结合的蛋白，并检验其他癌基因激活的衰老细胞中是否有相同复合物；同时以该复合物为导向，筛选和验证SAHF在全基因组范围内的抑制靶点。通过以上研究，有望对SAHF的形成机理进行深刻阐述，加深对癌基因诱导细胞衰老这一复杂有趣的生物学现象的理解；同时，为发现新的肿瘤治疗靶蛋白，开发新型癌症诊断和治疗试剂提供理论指导。

Oncogene-induced senescence (OIS) is one of the most important topics in today's aging and cancer research areas. Senescence-associated heterochromatic foci (SAHF) play an essential role in the initiation and maintenance of OIS. The mechanism of SAHF formation and the specific gene targets suppressed by SAHF are the two most appealing aspects of OIS study. A major difference between SAHF and common heterochromatin is that the folding of the tightly packed structures of SAHF is irreversible. In addition, increasing evidence supports that SAHF are specific for their gene targets, and this selective suppression of gene transcription is crucial to the regulation of OIS process. Basing on our previous studies and latest results, we hypothesize that BRG1-HP1-H3K9me protein complexes do exist in senescent cells, and these complexes are the core structures for SAHF formation. In this project, we propose to overexpress H-RasG12V to induce cellular senescence and use a variety of methods to prove the existence of BRG1-HP1-H3K9me complexes in senescent cells. Then we plan to use a series of methods to regulate the formation of BRG1-HP1-H3K9me complexes and study their effects on SAHF formation. Additionally, we will search for other proteins which might also interact with BRG1-HP1-H3K9me complexes. We also will investigate whether the activation of other oncogenes will induce BRG1-HP1-H3K9me complexes, and whether these complexes exist in other cell lines after Ras activation. After we have a comprehensive understanding of BRG1-HP1-H3K9me complexes, we will search for the bound DNA of these complexes genome-wide, and verify these gene candidates. This study is expected to have great contribution to the mechanism of SAHF formation, and help researchers to profoundly understand complex oncogene-induced senescence. By searching for preferential targets of SAHF, we may nominate novel targets for cancer treatment and provide better theoretical foundation for the development of diagnostic and therapeutic reagents to treat cancers.