Transcriptional silencing by the Bcl-6 oncoprotein

Bcl-6 癌蛋白的转录沉默

• 批准号: 7176939
• 负责人: ARI M. MELNICK
• 金额: $ 25.97万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-04-06 至 2009-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7176939
• 关键词: Affinity; Animal Disease Models; Animal Model; B-Cell Lymphomas; B-Lymphocytes; BTB/POZ Domain; Binding; Biological; Biological Assay; Cattle; Cell Cycle; Cell Survival; Cells; Chromatin Structure; Class; Data; Depth; Development; Disease; Epigenetic Process; Gene Silencing; Gene Targeting; Genes; Genetic Transcription; Genome; Genomics; Human; Immunoglobulin Somatic Hypermutation; In Vitro; Knock-out; Lateral; Literature; Lymphoma; Maintenance; Malignant Neoplasms; Mediating; Medical; Methylation; Modality; Molecular; Molecular Mechanisms of Action; Mus; Mutate; Mutation; N-terminal; Nucleic Acid Regulatory Sequences; Oncogene Proteins; Oncogenic; Pathway interactions; Patients; Peptides; Phenotype; Play; Point Mutation; Protein Family; Proteins; Publishing; Reagent; Relative (related person); Repression; Role; SMRT protein; Specificity; Standards of Weights and Measures; Structure; Structure of germinal center of lymph node; Surface; Testing; Therapeutic; Tissues; Transcription Repressor/Corepressor; Transcriptional Regulation; Validation; X-Ray Crystallography; Xenograft procedure; base; chromatin immunoprecipitation; design; epigenomics; gene repression; human NCOR1 protein; in vivo; inhibitor/antagonist; insight; malignant phenotype; novel; pre-clinical; prevent; protein protein interaction; research study; tumor growth

DESCRIPTION (provided by applicant): The Bcl-6 transcriptional repressor is the most commonly mutated oncoprotein in B-cell lymphomas. Mutations of its regulatory regions occur in approximately 50% of patients, leading to deregulated expression of Bcl-6 with consequent differentiation block and aberrant cell survival. The N-terminal BTB/POZ domain of Bcl-6 is required for its transcriptional functions. By X-ray crystallography we found that the Bcl-6 BTB domain binds directly to its co-repressor partner proteins through a non-conserved "lateral groove" motif. The reciprocal surface is provided by a short sequence present in the SMRT, N-CoR and BCoR corepressors. Point mutations in this "COW' motif cause loss of physical and functional interactions between corepressors and Bcl-6 in vitro and in vivo. This could be of major functional relevance for Bcl-6, since corepressor interaction is required for this protein to mediate transcriptional repression. We hypothesize that the lateral groove plays a critical role in Bcl-6 dependent repression. Therefore, we designed peptide inhibitors that prevent co-repressor interaction with Bcl-6. These reagents will be used to "conditionally knock out" the contribution of the SMRT/N-CoRJBCoR co-repressors to silencing by Bcl-6. This will allow us to determine the relative contribution of these corepressors to the genomic and epigenomic transcriptional mechanisms of Bcl-6. Such results can be obtained by combining high-throughput chromatin structure analysis by ChIP on chip and differential methylation hybridization with standard expression arrays. Validation through specific studies on independent loci is also required. Finally, we predict that lateral groove blockade of Bcl-6 will counteract the oncogenic activity of Bcl-6 and constitutes a novel and specific transcription therapy approach for B-cell lymphomas. We will assess the ability of lateral groove blockade to reverse the malignant phenotype of B-cell lymphoma cells as well as its capacity to alter the course of disease in pre-clinical animal models of this disease. Collectively, these results will reveal novel and important insights into the mechanism of action of Bcl-6 transcriptional repression, as well as provide the basis for a novel and specific molecular therapeutic modality for patients with B-cell lymphomas.

描述（申请人提供）：Bcl-6转录抑制因子是B细胞淋巴瘤中最常见的突变癌蛋白。其调控区的突变发生在大约50%的患者中，导致Bcl-6表达失调，从而导致分化阻滞和异常细胞存活。Bcl-6的N端BTB/POZ结构域是其转录功能所必需的。通过X射线晶体学分析，我们发现Bcl-6 BTB结构域通过一个非保守的“侧沟”基序直接与其辅阻遏物伴侣蛋白结合。相互表面由SMRT、N-CoR和BCoR辅阻遏物中存在的短序列提供。在这个“COW”基序的点突变造成的损失的物理和功能之间的相互作用的辅阻遏物和Bcl-6在体外和体内。这可能是Bcl-6的主要功能相关性，因为辅阻遏物相互作用是该蛋白介导转录抑制所必需的。我们推测侧沟在Bcl-6依赖性抑制中起关键作用。因此，我们设计了防止与Bcl-6的共阻遏物相互作用的肽抑制剂。这些试剂将用于“条件性敲除”SMRT/N-CoR/BCoR共阻遏物对Bcl-6沉默的贡献。这将使我们能够确定这些辅阻遏物对Bcl-6的基因组和表观基因组转录机制的相对贡献。这样的结果可以通过将ChIP芯片上的高通量染色质结构分析和差异甲基化杂交与标准表达阵列相结合来获得。还需要通过对独立位点的具体研究进行验证。最后，我们预测Bcl-6的侧沟阻断将抵消Bcl-6的致癌活性，并构成一种新的和特定的B细胞淋巴瘤的转录治疗方法。我们将评估侧沟阻断逆转B细胞淋巴瘤细胞恶性表型的能力，以及其在该疾病的临床前动物模型中改变病程的能力。总的来说，这些结果将揭示新的和重要的见解Bcl-6转录抑制的作用机制，以及提供一个新的和特定的分子治疗模式的B细胞淋巴瘤患者的基础。