Mutation Analysis of Thyroid Hormone Function

甲状腺激素功能突变分析

• 批准号: 6918119
• 负责人: JOHN D BAXTER
• 金额: $ 33.33万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-05-01 至 2010-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6918119
• 关键词: X ray crystallography; binding sites; gene induction /repression; gene mutation; hormone receptor; hormone regulation /control mechanism; nuclear receptors; protein isoforms; protein protein interaction; protein structure function; receptor binding; retinoid binding proteins; site directed mutagenesis; thyroid hormones; tissue /cell culture; transcription factor

Thyroid hormone (TH) signals are transduced by two related thyroid receptors (TRs) that regulate gene expression and are members of the nuclear receptor (NR) superfamily, which also includes receptors for steroids, vitamins and fatty acids and a variety of cholesterol and fatty acids and their metabolites. About 20% of current Pharmaceuticals are ligands that bind to NRs, underlining the importance of the NR family. TH regulates fat mass, cholesterol, heart and other functions; thus developing means to selectively regulate TR actions could lead to useful Pharmaceuticals with selective actions. We have utilized X-ray crystallographic information about the TR ligand-binding (LBD) and DMA-binding (DBD) domains to guide placements of mutations on the TR to analyze the mechanism of TR action. This mutagenesis approach has already allowed us to define LBD surfaces for binding downstream coregulators that mediate changes in gene expression, arid for forming TR-TR dimers and heterodimers with the retinoid X-receptor (RXR). The results also identified sites that might be targets for novel Pharmaceuticals. In the proposed studies we use our large bank of mutations and additional proposed mutations to determine: how receptors discriminate between various corepressors; the molecular basis of a novel mode of binding of TR to a coactivator (PGC-1); how the TR and RXR adapt to recognize diverse orientations of their DMA binding sites; mechanisms whereby TH regulates receptor binding to DMA; the role of salt bridges that influence several different TR functions in the unliganded vs. the liganded modes; and how a novel ligand exhibits selectivity for binding a particular TR isoform by inserting a side group between structures outside the ligand-binding cavity. These studies should provide substantial insight into TR function that is relevant for understanding TR action, mechanism of action of other NRs, regulation of gene expression and pharmaceutical design.

甲状腺激素 (TH) 信号由调节基因表达的两个相关甲状腺受体 (TR) 转导，并且是核受体 (NR) 超家族的成员，该家族还包括类固醇、维生素和脂肪酸以及各种胆固醇和脂肪酸及其代谢物的受体。目前约 20% 的药物是与 NR 结合的配体，这凸显了 NR 家族的重要性。 TH 调节脂肪量、胆固醇、心脏和其他功能；因此，开发选择性调节 TR 作用的方法可能会产生具有选择性作用的有用药物。我们利用有关 TR 配体结合 (LBD) 和 DMA 结合 (DBD) 结构域的 X 射线晶体学信息来指导 TR 上突变的放置，以分析 TR 作用机制。这种诱变方法已经使我们能够定义LBD表面，用于结合介导基因表达变化的下游共调节子，并与类维生素A X受体（RXR）形成TR-TR二聚体和异二聚体。结果还确定了可能成为新型药物目标的位点。在拟议的研究中，我们使用大量的突变库和其他拟议的突变来确定：受体如何区分各种辅阻遏物； TR 与共激活剂 (PGC-1) 结合的新模式的分子基础； TR 和 RXR 如何适应识别其 DMA 结合位点的不同方向； TH 调节受体与 DMA 结合的机制；盐桥的作用影响未配体与配体模式中几种不同的 TR 功能；以及新型配体如何通过在配体结合腔外的结构之间插入侧基来表现出结合特定 TR 同工型的选择性。这些研究应该提供对 TR 功能的深入了解，这与理解 TR 作用、其他 NR 的作用机制、基因表达调控和药物设计相关。