PERMEABILITY MEDIATED BY CONNEXIN CHANNELS

通过缝隙连接的细胞间信号传导的生理学是 仍然是个谜 尽管在理解方面取得了相当大的进展， 连接通道的生物化学、遗传学和生物合成， 它们最突出的功能特性的特征- 对信号分子的渗透性-仍然未知。 这 化学信号通过连接蛋白通道，以及 影响深远的根本问题。 间隙连接通道（由连接蛋白组成）形式受调节 介导离子和小分子直接细胞间转移的途径 分子。 对这条通道的研究受到其位置的限制， 原位;孔的两端都是细胞内的，大多数人无法进入。 探索信道选择性的操作。 研究 连接蛋白渗透倾向于集中于小原子离子或大原子离子 荧光示踪剂。 然而，这是特定的选择性 具有重要生物学意义的信号分子。 还有， 由于进入是通过细胞质，因此难以鉴定调节性 直接作用于通道以改变渗透性的因素， than via通过cellular细胞components组件. 长期目标是了解分子运作 这条细胞间通讯的途径。 该方法是 研究重组系统中的连接蛋白通道， 可以充分探索选择性渗透性能。 本研究 使用由连接蛋白32和连接蛋白26形成的通道 来自天然组织和表达载体的免疫组化， 一个特征良好的系统，产生不可用的信息 从细胞研究。 拟议的实验解决这些问题 问题：连接蛋白通道是否在信号分子中进行选择 (e.g.,第二信使）通过特定的分子亲和力？ 什么 是不同物种的独特分子选择性 连接蛋白？ 分子大小和电荷如何影响 渗透到渠道？ 什么是直接调制器 连接蛋白通道及其作用机制？ 通过研究连接蛋白通道， 系统，人们希望了解的基本属性 连接通信 缝隙连接是如此广泛， 连接蛋白通道选择性的阐明将具有深刻的意义。 影响了整个细胞和发育生物学。 目前已知有12种连接蛋白。 中的遗传缺陷 连接蛋白32导致周围神经病变，而连接蛋白43 心脏发育缺陷。 毫无疑问，许多其他综合症 全部或部分由连接蛋白通道功能缺陷引起。 连接蛋白通道的功能缺陷将反映在一个 异常的细胞间渗透性（高或低）到细胞质 分子。 拟议的研究解决了这一问题的基础 可能会出现

The physiology of intercellular signaling through gap junctions is still a mystery. In spite of considerable progress in understanding the biochemistry, genetics and biosynthesis of junctional channels, the character of their most salient functional property - permeability to signaling molecules - remains unknown. Which chemical signals go through connexin channels, and how well, are fundamental issues with far-reaching impact. Gap junction channels (composed of connexin) form regulated pathways mediating direct intercellular transfer of ions and small molecules. Study of the pathway is constrained by its location in situ; both ends of the pore are intracellular, inaccessible to most manipulations that explore channel selectivity. Studies of connexin permeation tend to focus on small atomic ions or large fluorescent tracers. Yet, it is the selectivity among specific signaling molecules that is of key biological importance. Also, since access is via cytoplasm, it is difficult to identify modulatory factors acting directly on the channel to alter permeability, rather than via cellular components. The long-term objective is to understand the molecular operation of this pathway of intercellular communication. The approach is to study connexin channels in a reconstituted system where their selective permeation properties can be fully explored. This study uses channels formed by connexin32 and connexin26 immunopurifield from native tissues and expression vectors in a well-characterized system that yields information not available from cellular studies. The proposed experiments address these questions: Do connexin channels select among signaling molecules (e.g., second messengers) by specific molecular affinities? What are the distinctive molecular selectivities of the different connexins? How do molecular size and charge affect what can permeate the channels? What are the direct modulators of connexin channels, and their mechanisms of action? By study of connexin channels in an experimentally accessible system, one hopes to understand the fundamental properties of junctional communication. Gap junctions are so widespread that elucidation of connexin channel selectivity will have profound consequences throughout cellular and developmental biology. There are currently 12 known connexins. Genetic defects in connexin32 cause a peripheral neuropathy, and in connexin43 defects of cardiac development. No doubt many other syndromes arise in toto or in part from defects in connexin channel function. A functional ~defect~ of connexin channels will be reflected in an abnormal intercellular permeability (high or low) to a cytoplasmic molecule. The proposed studies address the basis for how this may occur.