The Role of Fyn in Cell Death Signaling Pathways in Neonatal Hypoxia-Ischemia

描述（由申请人提供）： 新生儿中风是发病率和死亡率的重要原因;然而，目前没有针对新生儿的治疗方法。导致脑损伤的机制之一是NMDA受体（NMDAR）的过度激活。这导致钙离子的流入和几类分子向NMDAR的募集。其中一类是Src家族激酶（SFK）。它们被募集到NMDAR中以响应成年和发育中的大脑中的缺血。SFK已通过NMDAR依赖性和独立性细胞死亡途径成为脑损伤的关键介质。然而，关于Src激酶增强未成熟脑中脑损伤的机制知之甚少。本实验室最近报道，新生儿缺氧缺血（HI）后，SFK Src和Fyn被募集到NMDAR，SFK抑制具有保护作用。初步数据表明，具有神经元特异性Fyn过表达的小鼠具有增加的脑损伤、死亡率和MAPK途径的激活。我们推测Fyn通过修饰NMDAR和激活MAPK途径增强新生儿HI后的细胞死亡。目的1将确定Fyn是否作用于p38通路的上游以促进缺氧-缺血的体内模型中的细胞死亡。在目的2中，我们将纯化HI或假手术后野生型和Fyn转基因小鼠中的NR 2B复合物。除了识别新的蛋白质招募到NMDAR，这种方法将使我们能够确定Fyn是否在重塑NMDAR复合物响应HI的作用。 公共卫生相关性： 本研究旨在探讨Fyn在新生儿局灶性脑缺血实验模型中促进脑损伤的分子机制。对Fyn激活损伤途径的特定途径的理解将为新疗法的开发提供信息。

DESCRIPTION (provided by applicant): Neonatal stroke is an important cause of morbidity and mortality; however there are currently no treatments available for the newborn. One of the mechanisms which contributes to brain injury is overactivation of the NMDA receptor (NMDAR). This leads to an influx of calcium ions and recruitment of several classes of molecules to the NMDAR. One such class is the Src family kinases (SFK). They are recruited to the NMDAR in response to ischemia in both the adult and developing brain. SFKs have emerged as critical mediators of brain injury via NMDAR dependent and independent cell death pathways. However, very little is known about the mechanisms by which Src kinases enhance brain injury in the immature brain. Our lab recently reported that SFKs Src and Fyn are recruited to the NMDAR after neonatal hypoxia-ischemia (HI) and SFK inhibition is protective. Preliminary data demonstrate that mice with neuron-specific Fyn overexpression have increased brain injury, mortality, and activation of the MAPK pathway. We hypothesize that Fyn enhances cell death after neonatal HI through modification of the NMDAR and activation of the MAPK pathway. Aim 1 will determine whether Fyn acts upstream of the p38 pathway to promote cell death in an in vivo model of hypoxia- ischemia. In Aim 2 we will purify the NR2B complex in wild type and Fyn-transgenic mice after HI or sham operation. In addition to identifying novel proteins recruited to the NMDAR, this approach will allow us to determine whether Fyn plays a role in remodeling the NMDAR complex in response to HI. PUBLIC HEALTH RELEVANCE: This proposal investigates the molecular mechanisms by which Fyn contributes to brain injury in an experimental model of focal ischemia in the neonate. An understanding of the specific pathways by which Fyn activates injury pathways will inform the development of novel therapeutics.