Lipid Reguation of Voltage-gated Sodium Channels

电压门控钠（Nav）通道，像所有离子通道一样，是跨越脂质双分子层的蛋白质，允许离子从细胞膜的一边传导到另一边。因此，离子通道与它们所嵌入的脂质密切相互作用。近年来，我们开始认识到细胞内脂质结构的复杂性和动态性，以及细胞膜的理化性质（头群、酰基尾不饱和程度、疏水厚度、曲率）可能通过直接和间接的脂质-蛋白质相互作用来调节蛋白质的功能。然而，尽管离子通道与膜的密切相互作用可能是其功能的主要决定因素，但离子通道的脂质调节在很大程度上仍未被表征。这是因为直到最近，由于无法获得纯化通道，并且这些研究只能在脂质组成复杂，知之甚少且难以控制的细胞中进行，因此解决离子通道脂质调节的努力在很大程度上仍然是定性的。鉴于我之前对其他离子通道的研究，我假设Nav通道是由它们所嵌入的膜脂的物理化学性质调节的。最近在纯化Nav通道的功能性细菌同源物方面取得了重大突破，使我们能够通过将纯化的细菌Nav蛋白重组成确定成分的脂质体来检测它们的脂依赖性。将这种方法与其他生物物理和结构技术（脂质结合测定、通量测定、电生理记录、LRET、SAXS和质谱）相结合，将使我们能够将对脂质调节的理解扩展到一类新的通道，揭示Nav通道中调节的新机制，并了解其脂质调节的潜在分子基础。这些数据将使我们能够揭示细胞系统中无法获得的Nav通道调节的新机制，并为电压门控离子通道中脂质调节的趋同或发散进化提供见解

Voltage-gated sodium (Nav) channels, like all ion channels, are proteins that span across the lipid bilayer to allow for the conduction of ions from one side of a cellular membrane to the other. Thus, ion channels intimately interact with the lipids in which they are embedded. In recent years, we are now gaining appreciation for the complexity and dynamic nature of the lipid landscape, which vary both spatially and temporally within a cell, and that the physiochemical properties of the cell membrane (headgroup, degree of acyl tail unsaturation, hydrophobic thickness, curvature) may regulate the function of proteins through direct and indirect lipid-protein interactions. However, although the intimate interaction of ion channels with the membrane can be a major determinant of their function, lipid regulation of ion channels remains largely uncharacterized. This is because until recently, efforts to address lipid regulation of ion channels remained largely qualitative because of the inability to obtain purified channels and because these studies could be only performed in cells where lipid composition is complex, poorly understood and difficult to control. In view of my previous work with other ion channels, I hypothesize that Nav channels are regulated by the physiochemical properties of the membrane lipids in which they are embedded. Critical breakthroughs in purifying functional bacterial homologues of Nav channels have been recently made, enabling us to examine their lipid dependence by reconstituting purified bacterial Nav proteins into liposomes of defined composition. Combining this approach with other biophysical and structural techniques (lipid binding assays, flux assays, electrophysiological recordings, LRET, SAXS, and mass spectrometry) will enable us to expand our understanding of lipid regulation to a new class of channels, to uncover novel mechanisms of regulation in Nav channels and understand the underlying molecular basis for their lipid regulation. These data will allow us to uncover novel mechanisms of regulation in Nav channels that are otherwise unobtainable in cellular systems and provide insights into the convergent or divergent evolution of lipid regulation in voltage-gated ion channels.**