Genetic Analysis of Neuronal Hypoxic Stress Resistance

创伤性脑损伤（TBI）和缺血性脑卒中是发病和致残的主要原因，它们通过缺氧和氧化应激、谷氨酸受体过度激活和钙稳态失调引起的兴奋性毒性杀死神经元。特别是，创伤或中风引起的缺氧导致膜去极化，从而从受影响的神经元释放神经递质谷氨酸。高水平的急性谷氨酸过度激活邻近神经元上的受体，从而导致钙内流和兴奋性毒性。直接干扰受体激活的药物由于其对受体生理功能的巨大影响，其临床适用性有限。因此，确定新的治疗靶点以减轻脑外伤或脑卒中后的兴奋性毒性是很重要的。谷氨酸受体的调节运输可以改变突触的功效，这一发现改变了人们对神经元创伤后受体参与兴奋性毒性机制的思考。特别是，在一些培养的神经元系统中，创伤后缺氧后受体进出突触膜的运动可以调节兴奋性毒性。谷氨酸受体运输的变化是否有助于完整动物的神经元死亡，或者它们是缺氧神经保护反应的一部分？什么因素在缺氧时调节谷氨酸受体的运输？该建议采用秀丽隐杆线虫的遗传方法来了解缺氧如何影响神经元细胞生物学。在Aim 1中，它研究了缺氧和已知的缺氧反应途径如何改变受体的膜运输。在Aim 2中，它描述了EGL-9（一种感知氧水平的PHD蛋白）如何调节LIN-10（一种已知调节谷氨酸受体运输的PTB/ pdz结构域蛋白）以应对缺氧。提出的实验在几个方面推动了这一领域的发展。首先，他们确定了一种新的缺氧反应途径。其次，他们展示了一种新的反应途径，神经元通过这种途径保护自己免受缺氧的影响。第三，它们表明受调节的受体贩运是潜在的机制。最后，它们为减少脑损伤和缺血性脑卒中后的脑损伤提供了潜在的新治疗靶点。

Traumatic brain injury (TBI) and ischemic stroke are leading causes of morbidity and disability, excitotoxically killing neurons via a combination of hypoxia and oxidative stress, glutamate receptor overactivation, and deregulated calcium homeostasis. In particular, the hypoxia resulting from trauma or stroke results in membrane depolarization and hence release of the neurotransmitter glutamate from affected neurons. High levels of acute glutamate overactivate receptors on neighboring neurons, thereby resulting in calcium influx and excitotoxicity. Agents that directly interfere with receptor activation have had limited clinical applicability because of their dramatic effect on receptor physiological function. Thus, it is important to identify new therapeutic targets in order to mitigate excitotoxicity after TBI or stroke. The discovery that regulated trafficking of glutamate receptors can modify synaptic efficacy has changed the thinking about mechanisms by which receptors contribute to excitotoxicity after neuronal trauma. In particular, the movement of receptors into and out of synaptic membranes after post-trauma hypoxia in some cultured neuronal systems can modulate excitotoxicity. Do changes in glutamate receptor trafficking contribute to neuronal death in the intact animal, or are they part of a neuroprotective response to hypoxia? What factors regulate glutamate receptor trafficking in response to hypoxia? This proposal takes a genetic approach in C. elegans to understand how hypoxia impacts neuron cell biology. In Aim 1, it examines how hypoxia and the known hypoxia response pathway alters the membrane trafficking of receptors. In Aim 2, it characterizes how EGL-9, a PHD protein that senses oxygen levels, regulates LIN-10, a PTB/PDZ-domain protein known to regulate glutamate receptor trafficking, in response to hypoxia. The proposed experiments advance the field in several ways. First, they identify a novel hypoxia response pathway. Second, they demonstrate a new response pathway by which neurons protect themselves from hypoxia. Third, they show that regulated receptor trafficking is the underlying mechanism. Finally, they provide potential new therapeutic targets for minimizing brain damage following TBI and ischemic stroke.