Mechanism of beta-Catenin and APC-Regulated Transcription at Wnt Target Genes

描述（由申请人提供）：该项目的目标是了解Wnt/¿-catenin的反式激活机制及其受腺瘤性大肠息肉病（APC）的调控，APC是一种在大多数人类结肠癌中发生突变的肿瘤抑制因子。初步数据显示，转移性肿瘤抑制因子-catenin通过募集APC肿瘤抑制因子，以及抑制偶联的辅激活因子和辅抑制因子复合物的交换，直接抑制Wnt/ -catenin依赖性基因，导致dna结合的LEF-1释放-catenin。APC和¿-catenin核复合物的新成分将通过强大和敏感的蛋白质组学分析鉴定，并通过基因组ChIP-Seq分析评估Wnt调控位点的募集（Aim 1）， APC介导的抑制和共调节剂交换的详细机制将在HT29-APC结肠癌细胞中定义（Aim 2），¿-catenin在这一过程中的作用将在前列腺和结肠癌细胞中研究。以及一种新型的无细胞检测系统，用于了解从LEF-1中释放的连环蛋白。总之，这些数据将确定控制wnt依赖性癌细胞生长的新蛋白，并揭示APC和α -catenin肿瘤抑制因子在细胞核中的未知作用。

DESCRIPTION (provided by applicant): The goal of this project is to understand the mechanism of Wnt/¿-catenin transactivation and its regulation by the adenomatous polyposis coli (APC), a tumor suppressor that is mutated in the majority of human colon cancers. Preliminary data show that the metastatic tumor suppressor ¿-catenin, plays a direct role in the repression of Wnt/¿-catenin-dependent genes through recruitment of the APC tumor suppressor, and repression-coupled exchange of coactivator and corepressor complexes, resulting in release of ¿-catenin from DNA-bound LEF-1. Novel components of APC and ¿-catenin nuclear complexes will be identified by robust and sensitive proteomics analyses and assessed for recruitment to Wnt regulatory loci by genomic ChIP-Seq analysis (Aim 1), the detailed mechanism of APC-mediated repression and coregulator exchange will be defined in HT29-APC colon cancer cells (Aim 2), and the role of ¿-catenin in this process will be studied in prostate and colon cancer cells, as well as in a novel cell-free assay system developed to understand ¿- catenin release from LEF-1. Together, these data will identify new proteins that control Wnt-dependent cancer cell growth and reveal previously unknown roles for the APC and alpha-catenin tumor suppressors in the nucleus.