Neuronal-targeted caveolin-1 as a therapy for traumatic brain injury

描述（由申请人提供）：在西方世界，创伤性脑损伤（TBI）是导致年轻人死亡和发病的主要原因。尽管进行了大量的调查工作，但旨在降低与TBI相关的发病率和死亡率的干预措施（例如，n -甲基- d -天冬氨酸受体（NMDAR）拮抗剂）都失败了。因此，迫切需要新的方法来治疗TBI。脑外伤后立即有大量谷氨酸释放，导致NMDAR过度激活和兴奋性毒性神经元损伤。NMDAR拮抗剂的试验基于抑制兴奋性毒性可以减轻损伤的概念。然而，最近的数据表明，谷氨酸受体的过度激活是短暂的（< 1小时），NMDAR的表达和信号在损伤后48小时内显著减少。同样，通常与神经元存活相关的信号通路和分子（如BDNF、TrkR、Src、ERK、cAMP和CREB）在脑外伤后数天至数周内减少。这些数据表明，保护性促生存信号的丧失可能对神经元损伤至关重要，TBI后保护性信号的恢复可能会减轻损伤的扩散，改善运动和认知功能。神经元信号可以通过膜/脂筏（MLR），富含鞘脂，胆固醇和支架蛋白的区域进行调节。MLR对突触的发育和稳定至关重要，也集中在神经元生长锥内。MLR的一个关键成分是小窝蛋白-1 (Cav-1)，这是一种胆固醇结合蛋白，可组织和支撑多种受体，包括NMDAR、AMPAR、gpcr和TrkR。因此，MLR中含有对神经元存活和生长至关重要的受体和信号分子。我们实验室的初步数据表明：1)TBI显著降低MLR及其相关蛋白（Cav-1、NMDAR、AMPAR、TrkR和PSD-95）；2)神经元靶向的Cav-1过表达增加MLR、NMDAR、AMPAR和TrkR；3) Cav-1增强bdnf介导的TrkR、Akt和ERK1/2的磷酸化；4)增强nmdar介导的P-Src、P-CaMKII和P-ERK1/2的激活；5)增加NMDAR、多巴胺1受体（D1R）、5- ht6和福斯克林介导的cAMP形成；6) Cav-1过表达增加树突轴和脊柱蛋白（23-tubulin， neurexin1a和drebrin），增加树突发芽和分支。Cav-1作为神经元信号传导的纽带，因此可能提供一个控制点，可以治疗靶向恢复脑损伤后的神经元功能。因此，本研究的核心假设是，Cav-1启动MLR形成，增强促存活信号通路，从而促进神经元存活、轴突萌发和树突生长，从而显著减少脑外伤后神经元损伤，显著改善运动和认知功能。

DESCRIPTION (provided by applicant): Traumatic brain injury (TBI) is the leading cause of mortality and morbidity among young people in the Western world. Despite intensive investigative efforts, interventions designed to reduce morbidity and mortality associated with TBI [(e.g., N-methyl-D-aspartate receptor (NMDAR) antagonists)] have failed. Therefore, there is a pressing need for novel approaches for the treatment of TBI. Immediately following TBI, there is a substantial release of glutamate, leading to hyperactivation of NMDAR and excitotoxic neuronal injury. Trials of NMDAR antagonist were predicated on the notion that suppression of excitotoxicity would mitigate injury. However, recent data indicate that hyperactivation of glutamate receptors is short lived (< 1 hr) and that there is a substantial reduction in NMDAR expression and signaling within 48 hr of injury. Similarly, signaling pathways and molecules that are normally associated with neuronal survival (such as BDNF, TrkR, Src, ERK, cAMP and CREB) are reduced days to weeks following TBI. These data suggest that loss of protective pro-survival signaling may be critical to neuronal injury, and restoration of protective signaling post TBI might attenuate the spread of injury and improve motor and cognitive function. Neuronal signaling can be regulated by membrane/lipid rafts (MLR), regions enriched in sphingolipids, cholesterol, and scaffolding proteins. MLR are essential for the development and stabilization of synapses and are also concentrated within neuronal growth cones. A key component of MLR is caveolin-1 (Cav-1), a cholesterol binding protein that organizes and scaffolds a multiple receptors including NMDAR, AMPAR, GPCRs, and TrkR. Hence, MLR contain the receptors and signaling molecules that are critical to neuronal survival and growth. Preliminary data from our laboratory demonstrate that 1) TBI significantly decreases MLR and their associated proteins (Cav-1, NMDAR, AMPAR, TrkR, and PSD-95); 2) neuronal-targeted Cav-1 overexpression increases MLR, NMDAR, AMPAR, and TrkR; 3) Cav-1 enhances BDNF-mediated phosphorylation of TrkR, Akt, and ERK1/2; 4) enhances NMDAR-mediated activation of P-Src, P-CaMKII, and P-ERK1/2; 5) increases NMDAR, Dopamine 1 receptor (D1R), 5-HT6, and forskolin-mediated cAMP formation; 6) Cav-1 overexpression increases dendritic shaft and spine proteins (23-tubulin, neurexin1a, and drebrin) and increases dendritic sprouting and branching. Cav-1 serves as a nexus for neuronal signaling, and thus may provide a control point that can be therapeutically targeted to restore neuronal function following TBI. Accordingly, the central hypothesis of this proposal is that Cav-1 initiates MLR formation and enhances pro-survival signaling pathways, thereby promoting neuronal survival, axonal sprouting and dendritic growth that results in a substantial reduction in neuronal injury and significantly improves motor and cognitive function post TBI.