Wang Qiqian, Liu Shenquan
School of Mathematics, South China University of Technology, Guangzhou, China.
Front Cell Neurosci. 2021 Apr 7;15:596953. doi: 10.3389/fncel.2021.596953. eCollection 2021.
Electrical synaptic transmission is an essential form of interneuronal communication which is mediated by gap junctions that permit ion flow. Three gene families (connexins, innexins, and pannexins) have evolved to form gap junctional channels. Each gap junctional channel is formed by the docking of the hemichannel of one cell with the corresponding hemichannel of an adjacent cell. To date, there has been a lack of study models to describe this structure in detail. In this study, we demonstrate that numerical simulations suggest that the passive transmembrane ion transport model, based on the generality of ion channels, also applies to hemichannels in non-junctional plasma membranes. On this basis, we established a gap junctional channel model, which describes hemichannels' docking. We simulated homotypic and heterotypic gap junctions formed by connexins, innexins, and pannexins. Based on the numerical results and our theoretical model, we discussed the physiology of hemichannels and gap junctions, including ion blockage of hemichannels, voltage gating of gap junctions, and asymmetry and delay of electrical synaptic transmission, for which the numerical simulations are first comprehensively realized.
电突触传递是神经元间通讯的一种重要形式，由允许离子流动的缝隙连接介导。三个基因家族（连接蛋白、内连接蛋白和泛连接蛋白）已经进化形成缝隙连接通道。每个缝隙连接通道由一个细胞的半通道与相邻细胞的相应半通道对接形成。迄今为止，缺乏详细描述这种结构的研究模型。在本研究中，我们证明数值模拟表明，基于离子通道普遍性的被动跨膜离子转运模型也适用于非连接质膜中的半通道。在此基础上，我们建立了一个缝隙连接通道模型，该模型描述了半通道的对接。我们模拟了由连接蛋白、内连接蛋白和泛连接蛋白形成的同型和异型缝隙连接。基于数值结果和我们的理论模型，我们讨论了半通道和缝隙连接的生理学，包括半通道的离子阻断、缝隙连接的电压门控以及电突触传递的不对称性和延迟，首次通过数值模拟全面实现了这些内容。
