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

描述(申请人提供)：新生儿中风是发病率和死亡率的一个重要原因；然而，目前还没有针对新生儿的治疗方法。NMDA受体(NMDAR)过度激活是导致脑损伤的机制之一。这导致了钙离子的涌入和几类分子对NMDAR的招募。一个这样的类别是Src家族激酶(SFK)。他们被招募到NMDAR，以应对成人和发育中的大脑的缺血。通过NMDAR依赖和独立的细胞死亡途径，SFK已成为脑损伤的关键介质。然而，关于Src激酶在未成熟大脑中增强脑损伤的机制知之甚少。我们实验室最近报道，在新生儿缺氧缺血(HI)后，SFK、Src和Fyn被招募到NMDAR，抑制SFK具有保护作用。初步数据显示，具有神经元特异性Fyn过度表达的小鼠增加了脑损伤、死亡率和MAPK途径的激活。我们假设Fyn通过修饰NMDAR和激活MAPK通路来促进新生儿缺氧缺血性脑损伤后的细胞死亡。目的1在体内缺氧缺血模型中，确定Fyn是否作用于p38通路的上游以促进细胞死亡。在目标2中，我们将在野生型和Fyn转基因小鼠中纯化HI或Sham手术后的NR2B复合体。除了识别招募到NMDAR的新蛋白外，这一方法还将使我们能够确定Fyn是否在重塑NMDAR复合体以响应HI方面发挥作用。 公共卫生相关性：这项建议调查了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激活损伤通路的具体途径的了解将有助于开发新的治疗方法。

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.