Novel strategies to prevent FcgRIIA-dependent platelet activation and thrombosis

预防 FcgRIIA 依赖性血小板活化和血栓形成的新策略

• 批准号: 8501660
• 负责人: Wolfgang Bergmeier
• 金额: $ 35.94万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-08-20 至 2015-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8501660
• 关键词: 1,2-diacylglycerol; 1-Phosphatidylinositol 3-Kinase; ADP Receptors; Agonist; Animal Model; Antibodies; Blood Platelet Disorders; Blood Platelets; Calcium; Clinical; Collagen; Cytoplasmic Granules; Data; Development; Diglycerides; Disease; Fc Receptor; Feedback; G-Protein-Coupled Receptors; Generations; Goals; Guanosine Triphosphate Phosphohydrolases; Hematological Disease; Hemorrhage; Hemostatic function; Heparin; Human; ITAM; Immune; Integrins; Knockout Mice; Link; Mediating; Minor; Modeling; Molecular; Morbidity - disease rate; Mus; Pathogenesis; Pathologic; Pathway interactions; Patients; Phospholipase C; Phosphorylation; Phosphotransferases; Physiological; Platelet Activation; Platelet aggregation; Play; Prevention; Protein Isoforms; Protein Tyrosine Kinase; Regulation; Research; Risk; Role; Safety; Second Messenger Systems; Signal Pathway; Signal Transduction; Signaling Molecule; Surface; Syndrome; Testing; Therapeutic; Thrombin; Thrombocytopenia; Thrombosis; Thromboxane A2; Thromboxanes; Transgenic Mice; Work; design; improved; inhibitor/antagonist; mortality; mouse model; novel; novel strategies; novel therapeutics; pre-clinical; prevent; receptor; receptor coupling; release of sequestered calcium ion into cytoplasm; second messenger; sensor; therapeutic target

DESCRIPTION (provided by applicant): Activation of the platelet Fc receptor, Fc?RIIA, is central to the pathogenesis of several immune- mediated thrombocytopenia and thrombosis (ITT) syndromes, including heparin-induced thrombocytopenia/thrombosis. One of the barriers to successful treatment of these thrombotic syndromes is that therapeutic targeting of platelet activation pathways to prevent thrombosis is either not effective or comes with an inherent risk of bleeding complications. The purpose of this proposal is a) to identify critical signaling molecules, which preferentially contribute to Fc?RIIA- mediated platelet activation and b) to develop therapeutic anti-platelet strategies to prevent pathologic thrombosis in ITT while minimizing bleeding complications. Our preliminary studies identify the tyrosine kinase Syk, the Ser/Thr kinase Akt, and the Ca2+ sensor CalDAG-GEFI as promising new targets for antiplatelet therapy in the setting of ITT. Downstream of ITAM-coupled receptors like Fc?RIIA, Syk is important for the activation of phospholipase C?2 and thus the generation of the second messengers Ca2+ and diacylglycerol. CalDAG-GEFI links an increase in intracellular Ca2+ to the signaling pathways regulating integrin activation, thromboxane generation, and granule release. Preliminary studies on Akt demonstrate that it is important for Fc?RIIA-induced calcium flux and integrin activation, thus linking it to Syk and CalDAG-GEFI. Preliminary results as well as work by us and others further demonstrate that Syk, CalDAG- GEFI, and Akt are particularly important for Fc?RIIA/ITAM-mediated platelet activation. With the proposed studies, we will improve our understanding of the molecular mechanisms by which CalDAG-GEFI (aim 1) and Akt (aim 2) contribute to Fc?RIIA-mediated platelet activation. In aim 3, we will validate Syk and Akt and explore CalDAG-GEFI as therapeutic targets in ITT. The safety and efficacy of pharmacologic inhibition of Syk and Akt for the treatment and prevention of ITT will be tested in our established mouse models. The utility of CalDAG-GEFI or Akt2 as therapeutic targets for the treatment of ITT will be evaluated in crosses between mice transgenic for the human Fc?RIIA and mice knockout for CalDAG-GEFI or Akt2. The successful completion of this proposal will accelerate the rational design of novel therapeutics for immune-mediated platelet disorders.

性状（由申请方提供）：血小板Fc受体Fc？RIIA是几种免疫介导的血小板减少症和血栓形成（ITT）综合征（包括肝素诱导的血小板减少症/血栓形成）发病机制的核心。成功治疗这些血栓性综合征的障碍之一是，靶向血小板活化途径以预防血栓形成的治疗要么无效，要么伴有出血并发症的固有风险。本建议的目的是a）确定关键的信号分子，优先有助于Fc？RIIA介导的血小板活化和B）开发治疗性抗血小板策略，以预防ITT中的病理性血栓形成，同时最大限度地减少出血并发症。我们的初步研究确定了酪氨酸激酶Syk，丝氨酸/苏氨酸激酶Akt，和钙离子传感器CalDAG-GEFI作为有前途的新的目标，抗血小板治疗的ITT设置。下游ITAM偶联受体如Fc？RIIA，Syk是重要的激活磷脂酶C？2，从而产生第二信使Ca 2+和甘油二酯。CalDAG-GEFI将细胞内Ca 2+的增加与调节整合素活化、血栓烷生成和颗粒释放的信号传导途径联系起来。Akt的初步研究表明，它是重要的Fc？RIIA诱导的钙流和整合素活化，从而将其与Syk和CalDAG-GEFI联系起来。初步结果以及我们和其他人的工作进一步表明，Syk，CalDAG- GEFI，和Akt是特别重要的Fc？RIIA/ITAM介导的血小板活化。与拟议的研究，我们将提高我们的理解的分子机制，CalDAG-GEFI（目的1）和Akt（目的2）有助于Fc？RIIA介导的血小板活化。在目标3中，我们将验证Syk和Akt，并探索CalDAG-GEFI作为ITT中的治疗靶点。将在我们建立的小鼠模型中测试Syk和Akt的药理学抑制用于治疗和预防ITT的安全性和功效。CalDAG-GEFI或Akt 2作为治疗ITT的治疗靶点的效用将在人Fc？RIIA和敲除CalDAG-GEFI或Akt 2的小鼠。该提案的成功完成将加速免疫介导的血小板疾病的新疗法的合理设计。