Glutamate Mediates Platelet Activation through an Ionotropic Glutamate Receptor

描述(申请人提供)：心血管疾病和中风是发病率和死亡率的主要原因。虽然许多病理生理过程在血管疾病的发展中起作用，但血栓形成通常是导致中风和急性冠状动脉综合征的事件。许多血小板受体和激活途径在其他类型的细胞中是保守的，包括神经元。血小板在激活过程中释放神经递质谷氨酸，但谷氨酸信号在血管系统中的作用尚不清楚。我们发现，血小板表达离子型谷氨酸受体，包括AMPA型受体(AMPAR)和红藻氨酸(KA)型受体(KAR)。此外，我们还证明了AMPA和KA受体信号增加了血小板的活化。我们假设，血小板表达功能性谷氨酸敏感复合体，可增加激动剂诱导的血小板活化和血栓形成。为了探索这一假说，我们提出了以下具体目标：具体目标1：明确谷氨酸介导的激动剂诱导的血小板活化增加的机制。我们将扩展我们广泛的初步数据，以进一步探索离子型谷氨酸受体对血小板激活的调节。利用流式细胞术、血小板聚集和全细胞膜片钳技术，我们将进一步剖析血小板谷氨酸信号转导。具体目的2：明确血小板谷氨酸受体辅助分子相互作用。AIM 2将侧重于促进AMPAR和KAR膜在血小板中定位和稳定性的分子机制。具体目的3：证明谷氨酸信号通路促进血栓形成和缺血再灌注损伤。为了进一步探索谷氨酸对血小板功能的调节，我们将使用体内测量血小板功能，包括出血时间和血栓形成。我们还将通过一个缺血再灌注损伤的模型来证明AMPAR和KAR促进血小板活化的重要性。公共卫生相关性：2001年，一份世界卫生报告指出，动脉粥样硬化血栓形成(缺血性心脏病和中风)是全球主要的死亡原因。血小板在心血管疾病中起着重要的作用，而血小板抑制剂是主要的治疗干预手段。这项拟议的研究将有助于阐明心血管疾病预防和治疗新疗法开发的新目标。

DESCRIPTION (provided by applicant): Cardiovascular disease and stroke are major causes of morbidity and mortality. Although many pathophysiological processes play a role in the development of vascular disease, thrombosis often is the event that precipitates stroke and acute coronary syndromes. Many platelet receptors and activation pathways are conserved in other cell types, including neurons. Platelets release the neurotransmitter glutamate during activation, but the role of glutamate signaling in the vasculature is unknown. We have discovered that platelets express ionotropic glutamate receptors, including the AMPA type receptor (AMPAR) and the Kainic Acid (KA) type receptor (KAR). Furthermore, we demonstrate that AMPA and KA receptor signaling increase platelet activation. We hypothesize that platelets express functional glutamate sensitive complexes that increase agonist induced platelet activation and thrombosis. To explore this hypothesis, we propose the following Specific Aims: Specific Aim 1: To define the mechanisms of glutamate mediated increase in agonist induced platelet activation. We will extend our extensive Preliminary Data to further explore the regulation of platelet activation by ionotropic glutamate receptors. Using flow cytometry, platelet aggregation, and whole cell patch clamp techniques we will further dissect platelet glutamate signaling. Specific Aim 2: To define platelet glutamate receptor accessory molecule interactions. Aim 2 will focus on the molecular machinery that facilitates AMPAR and KAR membrane localization and stability in platelets. Specific Aim 3: To demonstrate that glutamate signaling promotes thrombosis and ischemia-reperfusion injury. To further explore glutamate regulation of platelet function we will use in vivo measurements of platelet function, including bleeding time and thrombosis. We will also demonstrate the importance of the promotion of platelet activation by AMPAR and KAR using a model of ischemia- reperfusion injury. PUBLIC HEALTH RELEVANCE: In 2001, a World Health Report noted atherothrombosis (ischemic heart disease and stroke) to be the leading cause of death worldwide. Platelets have a prominent role in cardiovascular disease and platelet inhibitors are a main therapeutic intervention. The proposed study will help elucidate novel targets for the development of new therapies in the prevention and treatment of cardiovascular disease.