Liberation of Intracellular Zinc and Neuronal Cell Death

描述（由申请人提供）：本申请中描述的实验的主要目的是开发和评价脑缺血中高度创新的、机械上合理的神经保护策略。 在过去的十年中，在该基金的支持下，我们已经确定了一个Zn 2+介导的促凋亡信号通路，该通路以神经元质膜中的p38/Src双磷酸化Kv2.1编码的K+通道的SNARE依赖性插入达到高潮。 这一过程导致延迟整流K+电流的显著增强，介导了在受损神经元中建立半胱天冬酶和核酸酶活化的容许的最佳环境所需的细胞内K+的损失。虽然干扰负责细胞凋亡K+电流浪涌的过程可以有效地阻断神经元细胞死亡，但导致K+电流增强的上游信号传导事件都不是该途径所特有的。 在这里提出的初步研究中，我们表明，缺乏SNARE结合域的通道不支持凋亡电流浪涌。 此外，我们表明，过度表达的SNARE结合细胞内通道结构域单独是在体外神经保护。我们假设，干扰触发Kv2.1介导的凋亡K+电流浪涌的细胞过程可能为中风和相关损伤的神经保护提供高度特异性和有效的治疗策略。 为了充分评估这一假设，我们将提出以下实验具体目标：首先，我们将详细描述导致Kv2.1介导的凋亡K+电流浪涌的磷酸化和SNARE依赖性机制，其次，我们将研究使用细胞穿透肽干扰SNARE/Kv2.1相互作用是否是啮齿动物中风模型中可行的神经保护策略。 我们研究计划的长期目标是设计新的神经保护方法来治疗中风和相关的神经退行性疾病。通过Kv2.1介导的K+电流的浪涌的细胞内K+的损失可能构成皮层和海马神经元的凋亡性细胞死亡的普遍要求。 由于治疗人类神经系统疾病的有效神经保护策略仍然非常难以捉摸，因此概念上的创新研究，例如靶向神经元凋亡K+电流，不仅具有潜在的高度意义，而且迫切需要。

DESCRIPTION (provided by applicant): The main objective of the experiments described in this application is to develop and evaluate a highly innovative, mechanistically rational neuroprotective strategy in cerebral ischemia. During the last ten years with support from this grant, we have characterized a Zn2+-mediated apoptotic-enabling signaling pathway that culminates with the SNARE-dependent insertion of p38/Src dual phosphorylated Kv2.1-encoded K+ channels in the neuronal plasma membrane. This process results in a dramatic enhancement of delayed-rectifier K+ currents, mediating the loss of intracellular K+ required for the establishment of a permissive, optimal environment for caspase and nuclease activation in injured neurons. Although interfering with the processes responsible for the apoptotic K+ current surge can effectively block neuronal cell death, none of the upstream signaling events leading to the K+ current enhancement are specific for this pathway. In preliminary studies presented here, we show that channels lacking a SNARE binding domain do not support an apoptotic current surge. Moreover, we show that overexpression of the SNARE-binding intracellular channel domain alone is neuroprotective in vitro. We hypothesize that interfering with a cellular process that trigger the Kv2.1-mediated apoptotic K+ current surge may provides a highly specific and effective therapeutic strategy for neuroprotection in stroke and related injury. In order to adequately evaluate this hypothesis we will address the following experimental Specific Aims: First, we will characterize in detail the phosphorylation and SNARE-dependent mechanisms leading to Kv2.1-mediated apoptotic K+ current surges~ and second, we will investigate whether interfering with the SNARE/Kv2.1 interaction using cell-penetrating peptides is a viable neuroprotective strategy in a rodent stroke model. The long-term goal of our research program is to devise novel neuroprotective approaches for the treatment of stroke and related neurodegenerative conditions. The loss of intracellular K+ via a surge of Kv2.1-mediated K+ currents may constitute a ubiquitous requirement for apoptotic cell death of cortical and hippocampal neurons. As effective neuroprotective strategies to treat human neurological conditions continue to be highly elusive, conceptually innovative studies, such as targeting neuronal apoptotic K+ currents, are not only of potentially high significance, but also urgently needed.