Genetic Analysis of Neuronal Hypoxic Stress Resistance

描述(申请人提供)：创伤性脑损伤(TBI)和缺血性中风是致残率和致残率的主要原因，通过缺氧和氧化应激、谷氨酸受体过度激活和钙稳态失调的组合而兴奋毒性地杀死神经元。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因其对受体生理功能的显著影响而限制了其临床应用。因此，确定新的治疗靶点以减轻脑外伤或卒中后的兴奋性毒性是很重要的。谷氨酸受体的受控运输可以改变突触效能的发现，改变了人们对受体参与神经元创伤后兴奋性毒性机制的看法。尤其是，在某些培养的神经系统中，创伤后缺氧后受体进入和离开突触膜可以调节兴奋性毒性。谷氨酸受体转运的变化是否导致完整动物的神经元死亡，或者它们是对缺氧的神经保护反应的一部分？哪些因素调节谷氨酸受体在低氧时的转运？这一建议采用了线虫的遗传学方法，以了解低氧如何影响神经细胞生物学。在目标1中，它研究了低氧和已知的低氧反应途径如何改变受体的膜运输。在目标2中，它描述了EGL-9，一种感知氧气水平的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，对低氧做出反应。拟议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低氧反应途径。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，他们表明，受监管的受体交易是潜在的机制。最后，它们为减少脑外伤和缺血性中风后的脑损伤提供了潜在的新的治疗靶点。 与公共卫生相关：创伤性脑损伤和中风在大脑中造成缺氧(低氧)条件，触发神经递质谷氨酸的过度释放。高水平的谷氨酸反过来通过过度激活神经元的谷氨酸受体来杀死神经元。为了开发新的应用于治疗和预防创伤性损伤或中风后造成的脑损伤，了解谷氨酸受体是如何在低氧条件下调节的是至关重要的。

DESCRIPTION (provided by applicant): 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. PUBLIC HEALTH RELEVANCE: Traumatic brain injury and stroke create conditions of hypoxia (low oxygen) in the brain, triggering the excessive release of the neurotransmitter glutamate. High levels of glutamate in turn kill neurons by over- activating their glutamate receptors. It is critical to understand how glutamate receptors are regulated in response to hypoxia in order to develop novel applications for the treatment and prevention of brain damage resulting after traumatic injury or stroke.