Guanidinium Toxins as Tools for Sodium Ion Channel Study

描述（由申请人提供）：该计划的首要目标是开发小分子工具，用于了解与神经元细胞中电传输的高度复杂离子机制相关的离子通道蛋白功能。天然存在的胍类毒素--河豚毒素、石房蛤毒素、gonyautoxin 2/3和zetekitoxin AB --构成了这些研究的基础。尽管分子大小和拓扑结构存在明显差异，但所有四种分子都是电压门控钠离子通道（NaV）的强效阻断剂，其通过阻塞离子传导孔（位点I）的细胞外口来发挥作用。NaV的结构，其中存在10种哺乳动物亚型，和功能的研究已经从天然来源的河豚毒素，石房蛤毒素，和少量的结构相关的形式的可用性。在晶体学数据的情况下，分子，如gonyautoxin 2/3，zetekitoxin AB，和设计的石房蛤毒素模拟物结合蛋白质诱变实验将使目前的同源模型的通道孔受到挑战和完善。从这些类型的研究中获得的知识可能会导致在胍毒素之后形成新的化学制剂，这些化学制剂表现出NaV亚型的特异性活性。这些工具对于绘制发育或受损神经元中特定通道亚型的空间和时间分布是期望的。由于NaV通道被认为是炎症和神经性疼痛反应机制的主要参与者，因此作用于特定通道亚型的药物可能代表治疗此类疾病的下一代疗法。公共卫生相关性：我们有兴趣在分子水平上了解神经细胞如何导电，以及当神经受伤时电信号的过程如何受到影响。化学合成是驱动我们计划的引擎，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。这些研究的结果可以帮助指导开发治疗急性和/或慢性疼痛的新疗法。

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.