RAX, PKR and ethanol neurotoxicity

描述(由申请人提供)：胎儿酒精谱系障碍(FASD)是一系列因怀孕期间母亲饮酒而导致的永久性出生缺陷。FASD在美国学龄儿童人群中的患病率最近估计高达2%-5%，比唐氏综合症和自闭症更常见。与FASD相关的成本每年超过60亿美元。确定酒精毒性在大脑中的机制和确定有效的治疗靶点(S)被列为2009年至2014年国家酒精中毒战略计划的重要目标。中枢神经系统(CNS)损害是FASD患者的主要特征。小脑是中枢神经系统中对乙醇毒性最敏感的区域之一。神经元丢失是酒精最有害的影响之一，也是FASD观察到的许多行为缺陷的原因。在动物模型中，让幼年啮齿动物在大脑生长突发期的一段时间--出生后--暴露于乙醇中 第4天到第9天，相当于人的晚期妊娠--导致小脑浦肯野和颗粒神经元的显著损失。然而，乙醇导致发育中的小脑神经元丢失的潜在机制仍然很大程度上不清楚。本研究的目的是确定乙醇神经毒性的机制和预防和治疗FASD的新靶点(S)。双链RNA(DsRNA)激活的蛋白激酶(PKR)通过调节多种下游靶蛋白和信号通路来组织细胞自我防御系统，以应对不同的生理应激或病毒感染。在理化应激条件下，PKR被其细胞内激活剂RAX激活，导致蛋白质合成抑制和细胞凋亡，并参与了许多神经退行性疾病的发病机制。这项研究的中心假设是RAX介导的PKR激活调节乙醇诱导的发育中小脑的神经元丢失。具体目的1：研究通过RAX/PKR相互作用激活的PKR是否调节乙醇诱导的小鼠小脑发育过程中神经元的凋亡。具体目的2：确定通过靶向Rax或PKR表达抑制PKR或用PKR抑制剂抑制PKR是否能减轻乙醇诱导的小鼠小脑发育中的神经元丢失。具体目的3：确定Rax+/-小鼠、N-PKR-/-小鼠和PKR抑制剂注射小鼠对乙醇诱导的小脑行为障碍的抵抗力更强。

DESCRIPTION (provided by applicant): Fetal Alcohol Spectrum Disorders (FASD) are a range of permanent birth defects caused by maternal alcohol consumption during pregnancy. The prevalence of FASD in populations of younger school children is recently estimated as high as 2-5% in the United State and is more common than Down syndrome and autism. FASD-related costs are more than $6 billion annually. Identification of the mechanism of ethanol toxicity in the brain and determination of the effective therapeutic target(s) are cited as importat goals in the NIAAA Strategic Plan for 2009-2014. Central nervous system (CNS) damage is a major feature observed in FASD patients. The cerebellum is one of the most sensitive areas in the CNS to ethanol toxicity. Neuronal loss is one of the most deleterious effects of ethanol and is responsible for many of the behavioral deficits observed in FASD. In the animal model, exposure of infant rodents to ethanol during a portion of the brain growth spurt period - postnatal day (PD) 4 to 9, equivalent to the human third trimester - causes a significant loss of cerebellum Purkinje and granule neurons. However, the underlying mechanism for ethanol-induced neuronal loss in the developing cerebellum is still largely unclear. The goal of this proposed study is to identify the mechanism underlying ethanol neurotoxicity and the novel target(s) for the prevention and treatment of FASD. The double-stranded RNA (dsRNA)-activated protein kinase (PKR) organizes the cellular self-defense system in response to diverse physiochemical stresses or viral infection by regulating a variety of downstream target proteins and signal pathways. Activation of PKR by its intracellular activator RAX under physiochemical stress conditions leads to protein synthesis inhibition as well as apoptosis and has been implicated in the pathogenesis of a number of neurodegenerative diseases. The central hypothesis of the proposed study is that RAX-mediated PKR activation regulates ethanol- induced neuronal loss in the developing cerebellum. Specific Aim 1: To investigate whether PKR activation through RAX/PKR interaction regulates ethanol- induced neuronal apoptosis in the developing cerebellum of the mouse. Specific Aim 2: To determine whether inhibition of PKR by targeting RAX or PKR expression or by PKR inhibitors alleviates ethanol-induced neuronal loss in the developing cerebellum of the mouse. Specific Aim 3: To determine whether RAX+/- mice, N-PKR-/- mice or PKR-inhibitor-injected mice are more resistant to ethanol-induced cerebellar behavioral dysfunction.