Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458, USA; Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA.
Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA; Center on Aging, The Scripps Research Institute, Jupiter, FL 33458, USA; Program in Integrative Biology and Neuroscience, Florida Atlantic University, Jupiter, FL 33458, USA.
J Mol Biol. 2019 Jan 18;431(2):196-209. doi: 10.1016/j.jmb.2018.11.028. Epub 2018 Dec 5.
Despite the widespread consumption of ethanol, mechanisms underlying its anesthetic effects remain uncertain. n-Alcohols induce anesthesia up to a specific chain length and then lose potency-an observation known as the "chain-length cutoff effect." This cutoff effect is thought to be mediated by alcohol binding sites on proteins such as ion channels, but where these sites are for long-chain alcohols and how they mediate a cutoff remain poorly defined. In animals, the enzyme phospholipase D (PLD) has been shown to generate alcohol metabolites (e.g., phosphatidylethanol) with a cutoff, but no phenotype has been shown connecting PLD to an anesthetic effect. Here we show loss of PLD blocks ethanol-mediated hyperactivity in Drosophila melanogaster (fruit fly), demonstrating that PLD mediates behavioral responses to alcohol in vivo. Furthermore, the metabolite phosphatidylethanol directly competes for the endogenous PLD product phosphatidic acid at lipid-binding sites within potassium channels [e.g., TWIK-related K channel type 1 (K2P2.1, TREK-1)]. This gives rise to a PLD-dependent cutoff in TREK-1. We propose an alcohol pathway where PLD produces lipid-alcohol metabolites that bind to and regulate downstream effector molecules including lipid-regulated potassium channels.
尽管乙醇被广泛消费，但它的麻醉作用机制仍不清楚。正链醇可诱导麻醉，直到达到特定的链长，然后失去效力——这一观察结果被称为“链长截断效应”。据认为，这种截断效应是由离子通道等蛋白质上的醇结合位点介导的，但长链醇的这些位点在哪里，以及它们如何介导截断，仍然定义不清。在动物中，已经表明酶磷脂酶 D (PLD) 会产生具有截断效应的醇代谢物（例如磷脂酰乙醇），但没有表现型表明 PLD 与麻醉效应有关。在这里，我们显示 PLD 的缺失阻止了果蝇（黑腹果蝇）中乙醇介导的过度活跃，表明 PLD 介导了体内对酒精的行为反应。此外，代谢物磷脂酰乙醇直接在钾通道内的脂质结合位点与内源性 PLD 产物磷脂酸竞争 [例如，TWIK 相关钾通道型 1 (K2P2.1，TREK-1)]。这导致 TREK-1 中出现 PLD 依赖性截断。我们提出了一种酒精途径，其中 PLD 产生结合并调节下游效应分子（包括脂质调节钾通道）的脂质-醇代谢物。
