Chromatin Landscaping of TGF-P/SMAD Signaling Targets

TGF-P/SMAD 信号靶标的染色质景观

• 批准号: 6993685
• 负责人: Joel H. Saltz
• 金额: $ 16.76万
• 依托单位: OHIO STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-09-30 至 2009-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6993685
• 关键词: biological signal transduction; chromatin; chromatin immunoprecipitation; gene expression profiling; genetic regulation; growth inhibitors; human tissue; microarray technology; neoplasm /cancer genetics; neoplastic growth; ovary neoplasms; transcription factor; transforming growth factors

The TGF-beta/SMAD signaling network plays an important role in growth inhibition of normal epithelia. In neoplastic processes, genetic and epigenetic losses of TGF-beta/SMAD signaling can result in outgrowth and invasion of transformed cells. In ovarian cancer, it has recently been reported that TGF-beta/SMAD signaling can become non-responsive to activators of TGF-beta, despite the fact that upstream regulators, such as TbetaRII, remain genetically intact and functional. Thus, it appears that other aberrant events, perhaps affecting co-activators or co-repressors of this growth inhibitory pathway, trigger epigenetic perturbations in TGF-beta/SMAD downstream targets. These as of yet un-explored perturbations have the potential to gradually alter chromatin structure in and around promoters of target genes and may be somatically heritable. We hypothesize that epigenetic deregulation TGF-beta/SMAD signaling may alter transcriptional profiles of TGF-beta/SMAD target genes, resulting in the initiation and promotion of neoplastic outgrowth of the ovarian surface epithelium. To test our hypothesis, we will comprehensively survey and compare regional chromatin profiles (active or repressed state) of TGF-beta/SMAD target promoters in ovarian cancer versus normal epithelia. Relative to this epigenetic phenomenon, SMAD-mediated transcription regulation also depends on other mechanisms, such as tissue-specific factors, promoter sequences, and cooperative interaction with other DMA-binding transcription factors. We will use computational tools to identify putative TGF-beta/SMAD target sequences and determine their functional relationship with local chromatin structure in ovarian epithelia. A novel microarray-based ChlP-on-chip assay will be developed to experimentally determine whether chromatin remodeling (i.e., histone modifications) of these predicted promoters occurs in ovarian cancer. Statistical approaches will be proposed to model the interaction between SMAD complexes and altered chromatin structure and to define unique epigenetic signatures in ovarian cancer cells. Specifically, we will 1) develop KbTSMAD (Knowledge base of TGF-beta/SMAD signaling pathway), an information resource of the TGF-beta/SMAD signaling pathway and its direct target gene promoters; 2) determine profiles of chromatin remodeling in these downstream loci in ovarian cancer cells; and 3) develop statistical approaches for modeling the synergistic interaction between TGF-beta/SMAD complex and altered chromatin structure and for defining unique epigenetic signatures in ovarian cancer cells.

TGF-β/SMAD信号网络在正常上皮抑制中起重要作用。在肿瘤过程中，TGF-β/SMAD信号的遗传和表观遗传损失会导致转化细胞的产物和侵袭。在卵巢癌中，最近有报道称，尽管上游调节剂（例如TBETARII）在遗传上保持完整且功能性，但TGF-beta/smad信号传导对TGF-β激活剂无反应。因此，看来其他异常事件，也许会影响共同激活因子 或这种生长抑制途径的共抑制剂，触发TGF-beta/smad下游目标中的表观遗传扰动。这些尚未探索的扰动有可能逐渐改变靶基因启动子及其周围的染色质结构，并且可能是可以遗传的。我们假设表观遗传失调TGF-β/SMAD信号传导可能会改变TGF-beta/smad靶基因的转录特征，从而导致卵巢表面上皮的肿瘤生长的起始和促进。为了检验我们的假设，我们将全面调查和比较卵巢癌中TGF-β/SMAD靶启动子与正常上皮的TGF-β/SMAD靶启动子的区域染色质曲线（主动或抑制状态）。相对于这种表观遗传现象，SMAD介导的转录调控也取决于其他机制，例如组织特异性因素，启动子序列以及与其他DMA结合转录因子的合作相互作用。我们将使用计算工具来识别推定的TGF-β/SMAD目标序列，并确定其与卵巢上皮中局部染色质结构的功能关系。将开发一种基于微阵列的新型CHLP芯片测定法，以实验确定这些预测的启动子是否发生在卵巢癌中。统计方法将是 提议建模SMAD复合物与染色质结构改变的相互作用，并在卵巢癌细胞中定义独特的表观遗传特征。具体而言，我们将1）开发KBTSMAD（TGF-BETA/SMAD信号通路的知识库），TGF-BETA/SMAD信号通路及其直接靶基因启动子的信息资源； 2）确定卵巢癌细胞中这些下游基因座中染色质重塑的谱； 3）开发统计方法，用于建模TGF-beta/smad复合物与染色质结构改变并定义独特的表观遗传学之间的协同相互作用 卵巢癌细胞的特征。