Conformational regulation in integrin bidirectional transmembrane signaling

整合素双向跨膜信号传导的构象调控

• 批准号: 9130426
• 负责人: Jieqing Zhu
• 金额: $ 41.75万
• 依托单位: VERSITI WISCONSIN, INC.
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2016-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9130426
• 关键词: Adaptor Signaling Protein; Address; Adhesions; Adhesives; Adverse effects; Affect; Affinity; Agonist; Binding; Biological Process; Biology; Blood Platelets; Cell Surface Receptors; Cell Survival; Cell membrane; Cells; Clinical; Clinical Trials; Clot retraction; Cysteine; Cytoplasmic Tail; Development; Distal; Disulfides; Drosophila genus; Drug usage; Electrons; Epitopes; Extracellular Domain; Face; Family; Fibrinogen; Fluorescence; Goals; Health; Hemostatic function; Human; Immune; Immune response; Integrin Binding; Integrin Inhibition; Integrins; Label; Laboratories; Length; Leukocytes; Ligand Binding; Ligands; Malignant Neoplasms; Mediating; Membrane; Modeling; Molecular; Molecular Conformation; Mutagenesis; Pharmaceutical Preparations; Play; Process; Protein Binding; Protein Isoforms; Proteins; RGD (sequence); Regulation; Rest; Role; Scanning; Signal Transduction; Structure; Supporting Cell; Surface; Tail; Talin; Thrombocytopenia; Thrombosis; Transmembrane Domain; Treatment Efficacy; Tumor Angiogenesis; Work; base; cell motility; cell type; crosslink; design; extracellular; flexibility; improved; inhibitor/antagonist; man; mimetics; novel; novel strategies; novel therapeutics; organ growth; response; transmission process; tumor growth

 DESCRIPTION (provided by applicant): Integrins are α/ß heterodimeric cell surface receptors that, via their ability to exist in multiple conformations, regulate a diverse array of biological processes ranging from organ development to immune regulation to hemostasis. Proteins binding to either the extracellular or cytoplasmic face of an integrin can effect long-range conformational changes that are transmitted across the plasma membrane. Bi-directional signal transmission from outside to inside initiates cell signaling cascades supporting cell migration and survival, while binding of specific proteins to the cytoplasmic tails of the integrin (inside-ot signaling) induces long-range conformational rearrangements within the ectodomains that convert it from a resting to an activated (ligand-binding) competent state. Despite many studies over the past 25 years, exactly how inside-out and outside-in signaling is controlled through the transmembrane and cytoplasmic domains are still not understood at the structural level. Development of novel therapeutics free of confounding side effects requires an atomic level molecular understanding of these processes. We recently found that deleting the C-terminus of the α-subunits in integrins, including the platelet αIIbß3 and leukocyte aLß2, has a dramatic ad unexpected effect on the ability of integrins to undergo conformational change in response to inside-out signals. Aim 1 of this proposal will focus on defining this novel role of integrin a-subunit cytoplasmic domains, especially their less-conserved membrane distal region, in regulating integrin inside-out activation. Multiple independent approaches, including comprehensive mutagenesis, cysteine scanning accessibility, disulfide crosslinking, and cysteine fluorescence labeling of full-length integrins, will be employed to examine restructuring of integrin transmembrane and cytoplasmic domains in response to inside-out and outside-in signaling in coordination with the multiple active conformations of the ectodomain. Aim 2 will focus on a second important issue: namely, the observation that most RGD (Arg-Gly-Asp)-mimetic integrin antagonists in clinical trials or in clinical use for treating thrombosis or cance have the undesirable side effect of inducing thrombocytopenia and in some cases, thrombosis or enhanced tumor growth and angiogenesis. These effects appear to be due to drug-induced conformational changes leading to integrin activation and creation of neo-epitopes capable of inducing an immune response. Building on our recent structural studies, we will define at the atomic level the critical structural changes that take place when an integrin binds either small or large ligands. Findings made will be used to guide the development of novel integrin antagonists that block function without altering integrin conformation. Together, these complementary Specific Aims will reveal the molecular basis for ligand-induced integrin conformational change and provide the structure-based understanding of bidirectional integrin signaling necessary to facilitate development of novel integrin antagonists with potentially improved therapeutic efficacy.

 描述（应用程序提供）：整联蛋白是α/ß异二聚体细胞表面受体，通过它们具有多种构象的能力，可以调节从器官发育到免疫调节到止血的一系列生物学过程。结合整合素的细胞外或细胞质面结合的蛋白质可以影响跨质膜跨质构象变化。双向信号从外部到内部的传递启动了支撑细胞迁移和存活的细胞信号级联，同时将特定蛋白的结合与整合素的细胞质尾巴结合（内部信号传导）会影响远距离会议重排内的远程会议重排，从而将其从静止的（静息）转化为激活的（Ligigand-liganding）能力的能力。尽管在过去的25年中进行了许多研究，但在结构水平上仍然尚不清楚通过跨膜和细胞质结构域通过跨膜和细胞质结构域控制的内而外和外部信号传导。没有混杂副作用的新型治疗的发展需要原子水平的分子理解这些过程。我们最近发现，删除整合素中α-亚基的C末端，包括血小板αIIBß3和白细胞Alß2，对整合素的能力产生了巨大的AD AD意外影响，该效应响应于内而外信号。该提案的目标1将重点定义整联蛋白A-亚基细胞质结构域的新作用，尤其是其保守的膜远端区域，在控制整合素内外激活中。多种独立的方法，包括全面整合素的全面诱变，半胱氨酸扫描可及性，二硫键交联和半胱氨酸荧光标记，将使用与内部和外部信号相结合的整合蛋白跨膜和细胞质域的重组，以与内部和外部信号相结合。 AIM 2将重点放在第二个重要问题上：即，在临床试验中或用于治疗血栓形成或癌症的临床用途中，大多数RGD（Arg-Gly-Asp） - 模拟整合蛋白拮抗剂的观察结果具有诱导血栓形成的不可避免的副作用，在某些情况下，血栓形成或增强的肿瘤生长和血管生成。这些作用似乎是由于药物引起的会议变化，导致整联蛋白激活并创建能够诱导免疫反应的新症状。在我们最近的结构研究的基础上，我们将在原子级定义当整合素结合小或 大配体。提出的结果将用于指导新型整联蛋白拮抗剂的发展，这些拮抗剂在不改变整联蛋白构象的情况下阻断功能。总之，这些完整的特定目标将揭示配体诱导的整联蛋白会议变化的分子基础，并提供基于结构的双向整合素信号传导的理解，以促进具有潜在提高治疗效率的新型整合蛋白拮抗剂的发展。