Structure and function of CSL, the transcriptional regulator in the Notch pathway

描述（由申请人提供）：Notch通路的异常激活是T细胞急性淋巴细胞白血病（T-ALL）白血病发生的一个致病因素，T-ALL是儿童中最常见的白血病。在其他血液传播的癌症、实体瘤恶性肿瘤和病毒诱导的肿瘤中也观察到致癌性Notch信号传导。异常Notch信号传导与人类肿瘤形成相关的程度相当大，这强调了开发新的治疗方法的必要性，这些治疗方法可以直接操纵该途径。我们的长期目标是从分子水平上了解Notch通路是如何实现转录调控的。保守的转录因子CSL是Notch途径中的主要转录调节因子，其中心性使其成为治疗干预的有吸引力的靶标。虽然在确定CSL的结合伙伴方面取得了进展，但对这些复合物如何调节转录的结构细节知之甚少。该提案的目的集中在表征CSL介导的转录复合物与辅阻遏物和病毒蛋白。我们推测，变构的变化CSL和/或重叠的辅助调节剂结合位点的CSL的基础转换CSL从一个阻遏转录激活。为了检验我们的假设并实现我们的目标，我们将追求以下三个目标。(1)我们将通过创建基于CSL-Notch-Mastermind活性转录复合物的CSL界面突变体库来分析转录辅调节因子所利用的CSL结合表面。(2)我们将确定辅阻遏物CIR、SMRT和SHARP与CSL相互作用所需的最小结构域，并对这些复合物进行X射线结构分析。(3)我们将描绘的疱疹病毒蛋白EBNA 2，RTA，和拉娜结合CSL所必需的域，并确定这些复合物的X-射线结构。该提案的完成将阐明CSL转录复合物与辅阻遏物和疱疹病毒蛋白的分子细节，从而从根本上推进该领域，并为合理开发靶向CSL介导的转录复合物的药物提供结构基础。 “通俗语言”-细胞Notch通路的异常作用导致人类癌症。我们正在确定Notch通路组分的结构模型，以更好地了解通路功能，生物学和肿瘤发生，这将对疾病诊断，预防和治疗产生影响。

DESCRIPTION (provided by applicant): Aberrant activation from the Notch pathway is a causative factor in the leukemogenesis of T-cell acute lymphoblastic leukemia (T-ALL), the most common leukemia found in children. Oncogenic Notch signaling is also observed in other blood-borne cancers, solid tumor malignancies, and virally induced tumors. The considerable extent to which aberrant Notch signaling is associated with human neoplasias emphasizes the need for developing novel therapeutics that pharmacologically manipulate the pathway. Our long-term goal is to gain a molecular understanding of how transcriptional regulation is achieved in the Notch pathway. The conserved transcription factor CSL is the primary regulator of transcription in the Notch pathway, and its centrality makes it an attractive target for therapeutic intervention. While progress has been made in identifying binding partners of CSL, the structural details as to how these complexes regulate transcription are poorly understood. The objective of this proposal focuses on characterizing CSL-mediated transcription complexes with corepressors and viral proteins. We hypothesize that allosteric changes in CSL and/or overlapping coregulator binding sites on CSL underlie the conversion of CSL from a repressor to an activator of transcription. To test our hypothesis and accomplish our objective the following three aims will be pursued. (1) We will analyze the CSL binding surfaces utilized by transcriptional coregulators by creating a library of CSL interfacial mutants based on the CSL-Notch-Mastermind active transcription complex. (2) We will determine the minimal domains necessary for the corepressors CIR, SMRT, and SHARP to interact with CSL and pursue X-ray structures for these complexes. (3) We will delineate the domains of the herpesvirus proteins EBNA2, RTA, and LANA necessary for binding CSL and determine X-ray structures for these complexes. Completion of this proposal will illuminate the molecular details that comprise CSL transcription complexes with corepressors and herpesvirus proteins, thereby fundamentally advancing the field, and provide a structural basis for rationally developing drugs that target CSL-mediated transcription complexes. "Lay language" - The abnormal action of the cellular Notch pathway results in human cancers. We are determining structural models for Notch pathway components in order to better understand pathway function, biology and tumorigenesis, which will have an impact on disease diagnosis, prevention, and treatment.