Targeting PSD Proteins in the Treatment of CNS Injury

描述(申请人提供)：我的目标是找到一种治疗中风和中枢神经系统损伤的方法。这种损伤部分是由突触谷氨酸受体介导的，谷氨酸受体对中枢神经系统的功能也是必不可少的。用谷氨酸拮抗剂抑制突触功能是有害的，是治疗人类中风的失败方法。我们已经证明有毒的谷氨酸能信号被限制在不同的通路上，这表明它们可能被选择性地阻断，而不影响基本的突触活动。这项资助致力于我们发现神经毒性信号的分子机制，这种机制依赖于NMDAR与膜下支架蛋白的相互作用。一个关键的相互作用是NMDARs与支架蛋白PSD-95的相互作用。我们已经抑制了神经元PSD-95，它将NMDAR从一氧化氮合酶中分离出来，一氧化氮合酶是一种被PSD-95捆绑在NMDAR上的酶。这在不阻断突触活性的情况下阻断了NMDAR的毒性。最近，我们使用破坏NMDAR/PSD-95偶联的细胞预示性多肽，治疗动物中风。该疗法减少了大鼠局灶性脑缺血损伤，并在不阻断突触功能的情况下改善了它们的神经预后。我们的方法避免了阻断NMDAR的负面后果，并可能构成一种实用的中风治疗方法。我们建议进一步推行这一前景看好的方法。在目标1中，我们将确定我们发现的治疗分子的作用机制。在目标2中，我们将重点介绍通过分离NMDAR/PSD-95相互作用来治疗中风和中枢神经系统创伤的治疗限度(治疗窗口、作用时间、神经行为后果)和毒性。在目标3中，我们将根据PSD-95的下游相互作用来确定神经疾病的新治疗靶点。这一结果将提供有关疾病机制和突触功能的知识，并验证中风治疗的有效性，以期未来进入人体试验。

DESCRIPTION (provided by applicant): My goal is to find a treatment for stroke and CNS injury. Such injuries are partly mediated by synaptic glutamate receptors, which are also essential for CNS function. Curtailing synaptic function with glutamate antagonists is harmful and is a failed approach to treating stroke in humans. We have shown that toxic glutamatergic signals are restricted to distinct pathways, indicating that they might be blocked selectively, without affecting essential synaptic activity. This grant pursues our discovery of the molecular mechanism for neurotoxic signaling, which depends on NMDA receptor (NMDAR) interactions with submembrane scaffolding proteins. A key interaction is that of NMDARs with the scaffolding protein PSD-95. We have suppressed neuronal PSD-95, which uncoupled NMDARs from nitric oxide synthase, an enzyme tethered to NMDARs by PSD-95. This blocked NMDAR toxicity without blocking synaptic activity. More recently, using cell-permeant peptides that disrupt NMDAR/PSD-95 coupling, we treated stroke in animals. The treatment reduced focal ischemic brain damage in rats and improved their neurological outcome without blocking synaptic function. Our approach avoids the negative consequences of blocking NMDARs and may constitute a practical stroke therapy. We propose to pursue this promising approach further. In AIM 1 we will determine the mechanism of action of the therapeutic molecules that we discovered. In AIM 2 we will focus on the therapeutic limits (therapeutic window, duration of effect, neurobehavioral consequences) and toxicity of treating stroke and CNS trauma by dissociating NMDAR/ PSD-95 interactions. In AIM 3 we will identify novel therapeutic targets for neurological disease based on downstream interactions of PSD-95. The results will provide knowledge on mechanisms of disease and synaptic function, and validate a stroke treatment with the future intention of proceeding to human trials.