Guanidinium Toxins as Tools for Sodium Ion Channel Study

描述(由申请人提供)：该计划的主要目标是开发小分子工具，用于了解与神经元细胞电传输的高度复杂的离子机制相关的离子通道蛋白功能。天然的胍类毒物--河豚毒素、岩藻毒素、刚鱼毒素2/3和哲氏杆菌毒素AB--构成了这些研究的基础。尽管分子大小和拓扑结构明显不同，但这四个分子都是电压门控钠离子通道(NAV)的非常有效的阻断剂，NAV通过闭塞离子导孔的胞外口(位置I)来操作。随着河豚毒素、岩藻毒素和少量结构相关形式的天然来源的出现，对NAV结构和功能的研究取得了进展，其中哺乳动物有10种亚型。在缺乏结晶学数据的情况下，如刚鸟毒素2/3、泽曲霉毒素AB等分子，以及设计的岩藻毒素模拟物与蛋白质诱变实验相结合，将使现有的通道孔同源模型受到挑战和改进。从这些类型的研究中积累的知识可能导致新的化学试剂模仿显示NAV亚型特定活性的鸟粪毒素。这类工具是绘制发育中或受损神经元中特定通道亚型的空间和时间分布的理想工具。由于NAV通道被认为是炎症和神经病理性疼痛反应机制的主要参与者，针对特定通道亚型的药物可能代表着治疗此类疾病的下一代疗法。与公共健康相关：我们感兴趣的是在分子水平上了解神经细胞如何传导电流，以及当神经损伤时，电信号传递过程是如何受到影响的。化学合成是推动我们计划的引擎，并将使制备可用于研究这些复杂生物现象的选择性试剂成为可能。这些研究的结果可能有助于指导治疗急性和/或慢性疼痛的新疗法的开发。

DESCRIPTION (provided by applicant): The overarching aim of this program is to develop small molecule tools for understanding ion channel protein function associated with the highly complex ionic mechanisms of electrical transmission in neuronal cells. Naturally occurring guanidinium poisons - tetrodotoxin, saxitoxin, gonyautoxin 2/3, and zetekitoxin AB - form the bedrock of these investigations. Despite evident differences in molecular size and topology, all four molecules are exquisitely potent blockers of voltage-gated sodium ion channels (NaV) that operate by occluding the extracellular mouth of the ion conductance pore (Site I). Studies of NaV structure, of which there exist ten mammalian isoforms, and function have been advanced with the availability from natural sources of tetrodotoxin, saxitoxin, and small number of structurally related forms. In the absence of crystallographic data, molecules such as gonyautoxin 2/3, zetekitoxin AB, and designed saxitoxin mimics in combination with protein mutagenesis experiments would enable current homology models of the channel pore to be challenged and refined. Knowledge accrued from these types of studies could lead to new chemical agents patterned after the guanidinium toxins that demonstrate NaV subtype specific activity. Such tools are desirable for mapping the spatial and temporal distribution of specific channel isoforms in developing or injured neurons. As NaV channels are considered lead actors in mechanisms for inflammation and neuropathic pain response, drugs that act on specific channel subtypes could represent next-generation therapies for the treatment of such ailments. PUBLIC HEALTH RELEVANCE: We are interested in understanding at a molecular level how nerve cells conduct electricity and how the process of electrical signaling is affected when a nerve is injured. Chemical synthesis is the engine that drives our program and will make possible the preparation of selective reagents that can be used to investigate these complex biological phenomena. Results from these studies could help guide the development of new therapies for the treatment of acute and/or chronic pain.