Adaptive tissue permeability to alcohol in C. elegans

描述（由申请人提供）：过度饮酒会对肝脏、肾脏和大脑造成永久性损害。发育过程中对神经组织的损害可导致胎儿酒精综合征，这是智力迟钝的主要可预防形式。尽管人们普遍认为乙醇可以通过细胞膜脂质双分子层渗透到这些器官和胎盘中，但目前尚不清楚乙醇是如何比其他组织更容易渗透到某些组织中的。目前还不清楚是什么使这些组织对乙醇的渗透性增加，以及这是否可以动态改变以防止损伤。我们正在利用模型线虫秀丽隐杆线虫的强大遗传学来深入了解体内酒精渗透性的分子基础。这种模式生物已被用于发现参与基本生理过程的基因，包括酒精如何通过保守的分子靶点引起中毒。之前，我们和其他人发现秀丽隐杆线虫需要异常高浓度的外源乙醇（500-1000 mM）来产生中毒，并将内部组织浓度提高到与人类消耗相关的水平（20-50 mM）。我们现在发现，尽管秀丽隐杆线虫在低渗透压条件下（150 mOsm）对外源乙醇表现出这种非凡的抗性，但在较高（生理）渗透压条件下（320 mOsm）测试时，动物对乙醇恢复到与人类相似的敏感性。此外，我们发现秀丽隐杆线虫在生理渗透压下的短期孵育使其在低渗透压条件下对酒精具有类似人类的敏感性。我们假设特定的保守分子允许乙醇快速渗透到动物组织中，并且这些分子可以动态改变以改变渗透性。为了确定这种对乙醇的动态渗透性的分子基础，我们提出了三个具体目标：1)测试不同渗透途径的基因突变是否会降低线虫对乙醇的行为反应和组织对乙醇的渗透性。2)发现这些分子是否随着长期暴露于乙醇和/或渗透压而动态重组。3)确定这些分子是否在异源体系中改变对乙醇的渗透。对线虫中介导酒精渗透性的分子的鉴定将首先表明秀丽隐杆线虫对人类具有相当的敏感性，因此加强了它作为人类酒精滥用模型的理论依据，其次，提供了有吸引力的药物靶点，以防止人类酗酒后的组织损伤。

DESCRIPTION (provided by applicant): Over consumption of alcohol can permanently damage the liver, kidney and brain. Damage to the nervous tissue incurred during development can lead to fetal alcohol syndrome which is the main preventable form of mental retardation. Although ethanol is widely understood to penetrate these organs and the placenta by diffusing through the lipid bilayer of cell membranes, it is unclear how ethanol penetrates certain tissues more easily than others. It is also unknown what confers these tissues increased permeability to ethanol and whether this can be dynamically altered to prevent damage. We are taking advantage of the powerful genetics of the model nematode C. elegans to provide insight into the molecular basis of alcohol permeability in vivo. This model organism has been used to discover genes involved in fundamental physiological processes including how alcohol elicits intoxication through conserved molecular targets. Previously, we and others have found that C. elegans requires an unusually high concentration of exogenous ethanol (500-1000 mM) to produce intoxication and to raise the internal tissue concentration to a level relevant to human consumption (20-50 mM). We have now discovered that although C. elegans shows this extraordinary resistance to exogenous ethanol when tested in low osmolarity conditions (150 mOsm), the animal reverts to human-like sensitivity to ethanol when tested in higher (physiological) osmolarity conditions (320 mOsm). Moreover, we find that short-term incubation of C. elegans at physiological osmolarity confers human-like sensitivity to alcohol in low osmolarity conditions. We hypothesize that specific conserved molecules allow rapid permeation of ethanol into the tissue of the animal, and these molecules can be dynamically altered to change permeability. To determine the molecular basis for this dynamic permeability to ethanol we propose three specific aims: 1) Test whether mutation of genes in different permeation pathways reduce behavioral responses to ethanol and tissue permeability to ethanol in C. elegans. 2) Discover whether these molecules are dynamically reorganized with chronic exposure to ethanol and/or osmolarity. 3) Determine whether these molecules alter permeation to ethanol in a heterologous system. Identification of the molecules that mediate alcohol permeability in the worm would first show that C. elegans has comparable sensitivity to humans and therefore strengthen its rationale as a model for human alcohol abuse, and second, provide attractive drug targets to prevent tissue damage following binge drinking in humans. PUBLIC HEALTH RELEVANCE: Identification of the molecules that mediate dynamic alcohol permeability in C. elegans is important to human health for two main reasons. First, it would first show that this powerful model invertebrate has equivalent sensitivity to humans, and therefore strengthen rationale for using C. elegans as a model for studying the effects of human alcohol abuse. Second, this would provide attractive drug targets to prevent tissue damage by alcohol after binge drinking in humans.