Identification of Novel integrin antagonists

新型整合素拮抗剂的鉴定

• 批准号: 8355238
• 负责人: M. AMIN ARNAOUT
• 金额: $ 28.09万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-22 至 2014-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8355238
• 关键词: Accounting; Adhesions; Adult; Affect; Affinity; Agonist; Amino Acids; Arteries; Aspartate; Autoimmune Diseases; Autoimmune Process; Binding; Binding Sites; Blood Platelets; Blood Vessels; C-terminal; Cell Adhesion; Cell membrane; Cell physiology; Cells; Chronic Disease; Clinical Trials; Coupled; Crohn' s disease; Cytoskeleton; Development; Disease; Divalent Cations; Drug Delivery Systems; Epithelial; Evaluation; Event; Extracellular Matrix; Face; Foundations; Freezing; Glutamates; Growth; Hemorrhage; Hemostatic Agents; Homing; ITGAM gene; ITGB2 gene; Immune; Immunity; Inflammation; Inflammatory; Injury; Integrin Binding; Integrin-mediated Cell Adhesion Pathway; Integrins; Invaded; Ions; Kidney; Lead; Leukocytes; Ligand Binding; Ligands; Ligation; Mediating; Metals; Monoclonal Antibodies; Multiple Sclerosis; Myocardial Infarction; Natural regeneration; Nature; Neoplasm Metastasis; Outcome; Outcome Study; Oxygen; Parents; Peptides; Pharmaceutical Chemistry; Pharmaceutical Preparations; Physiological; Plasma; Play; Property; Reaction; Regulation; Role; Signal Transduction; Site; Solutions; Structure; Structure-Activity Relationship; Subgroup; Surface; Thrombosis; Tissues; Translating; adhesion receptor; base; carboxylate; design; falls; interdisciplinary approach; mimetics; mortality; novel; novel strategies; novel therapeutics; pathogen; prevent; receptor; receptor coupling; response; small molecule; structural biology; therapeutic target; von Willebrand Factor

DESCRIPTION (provided by applicant): Integrins are ¿/¿ heterodimeric adhesion receptors that play essential roles in kidney formation during development and in regeneration of the adult kidney following inflammatory or vascular injury. Abnormal integrin function can lead, however, to inflammatory, autoimmune and thrombotic disorders affecting the kidney and the vasculature, thus making integrins important therapeutic targets. Existing ligand-mimetic monoclonal antibodies (mAbs) and small molecules (fashioned based on structures of natural ligands) exert agonist-like properties, by engaging the integrin ligand binding site, like the parent physiologic ligand, thus inducing cell adhesion responses these drugs were designed to prevent, and underscoring the need for novel approaches targeting integrins in disease. Integrins comprise two subgroups, depending on the presence or absence of a von Willebrand's Factor Type A-domain (vWFA) (¿A- or I domain) found in one-half of the integrin ¿-subunits. ¿A mediates Mg2+- dependent binding of an aspartate (Asp) or glutamate (Glu) residue from integrin ligands (or ligand-mimetic drugs) at a metal-ion-dependent-adhesion site (MIDAS) in ¿A. ¿A-lacking integrins bind ligands through an ¿A-like domain (¿A or I-like) present in their ¿-subunits. The ligand Asp/Gu binds the Mg2+ at MIDAS monodentately, completing an octahedral coordination sphere around the metal ion. Formation of the Mg2+- Asp (or Glu) bond triggers activating conformational changes in the integrin leading to cell adhesion, accounting for the agonist-like properties of existing integrin antagonists. In solving the crystal structure of a ligand-mimetic mAb, which binds at MIDAS in the ¿A domain but prevents conformational switching in the integrin (i.e. acting as a pure antagonist), we found that a Ca2+ is heptacoordinated at MIDAS, the result of the unusual symmetric bidentate ligation by the mAb-derived Asp. Stable heptacoordination of Ca2+ blocked the conformational switching normally induced by ligand occupancy of MIDAS. We hypothesize that it should therefore be feasible to design structure-based cyclized peptide antagonists to the ¿A domain based on our crystal structure, and that switching ligand Asp coordination from the monodentate to the bidentate binding mode in the ¿A MIDAS, thus stabilizing a Ca2+ there, will also achieve a similar outcome in the ¿A-lacking integrins. The present proposal represents a multidisciplinary approach with participation by cell-, structural biology and medicinal chemistry groups. An outcome from these studies will be the development of new probes for assessing structure-activity relationships of these dynamic receptors and could provide new therapeutic strategies to treat a wide-spectrum of disease states affecting the kidney and the vasculature. PUBLIC HEALTH RELEVANCE: Improper activation of integrins plays critical roles in a diverse range of diseases including inflammatory, autoimmune diseases of the kidney and the vasculature as well as cancer metastasis. Current drugs targeting these receptors have contributed to adverse autoimmune reactions and to increased mortality, the result of inadvertent activation of integrins. Identifying drugs that maintain the integrin in the inactive state is highly desirable and is the subject of this proposal.

描述（由申请人提供）：整合素是异二聚体粘附受体，在肾脏发育过程中以及炎症或血管损伤后成人肾脏的再生中发挥重要作用。然而，整合素功能异常可导致影响肾脏和脉管系统的炎症、自身免疫和血栓性疾病，因此整合素成为重要的治疗靶点。现有的拟配体单克隆抗体（mab）和小分子（基于天然配体的结构）通过结合整合素配体结合位点（如亲本生理配体）发挥激动剂样特性，从而诱导细胞粘附反应，这些药物被设计用于预防，并强调需要针对疾病中的整合素的新方法。整合素包括两个亚群，这取决于在一半的整合素亚基中发现的血管性血友病因子类型a结构域（vWFA）（¿a -或I结构域）的存在与否。¿A介导整合素配体（或配体模拟药物）的天冬氨酸（Asp）或谷氨酸（Glu）残基在¿A的金属离子依赖粘附位点（MIDAS）的Mg2+依赖性结合。缺乏A的整合素通过其亚基中存在的A样结构域（A或i样）与配体结合。配体Asp/Gu在MIDAS单齿结合Mg2+，在金属离子周围形成八面体配位球。Mg2+- Asp（或Glu）键的形成触发激活整合素的构象变化，导致细胞粘附，这解释了现有整合素拮抗剂的激动剂样特性。在解拟配体单抗的晶体结构时，我们发现Ca2+在MIDAS是七配位的，这是单抗衍生的Asp不寻常的对称双齿连接的结果。Ca2+的稳定七配位阻断了MIDAS通常由配体占用引起的构象转换。因此，我们假设，基于我们的晶体结构设计基于结构的环化肽拮抗剂应该是可行的，并且在A MIDAS中将配体Asp从单齿结合模式切换到双齿结合模式，从而稳定Ca2+，也将在缺乏A的整合素中实现类似的结果。目前的建议代表了一个多学科的方法与参与细胞，结构生物学和药物化学组。这些研究的结果将是开发新的探针来评估这些动态受体的结构-活性关系，并可能为治疗影响肾脏和脉管系统的各种疾病状态提供新的治疗策略。