Trouet D, Hermans D, Droogmans G, Nilius B, Eggermont J
Laboratory of Physiology, Catholic University of Leuven, Campus Gasthuisberg, Leuven, B-3000, Belgium.
Biochem Biophys Res Commun. 2001 Jun 8;284(2):461-5. doi: 10.1006/bbrc.2001.4995.
Caveolae are flask-shaped invaginations of the plasma membrane formed by the association of caveolin proteins with lipid rafts. In endothelial cells, caveolae function as signal transduction centers controlling NO synthesis and mechanotransduction. We now provide evidence that the endothelial volume-regulated anion channel (VRAC) is also under the control of the caveolar system. When calf pulmonary artery endothelial (CPAE) cells were transfected with caveolin-1 Delta1-81 (deletion of amino acids 1 to 81), activation of VRAC by hypotonic cell swelling was strongly impaired. Concomitantly, caveolin-1 Delta1-81 disturbed the formation of caveolin-1 containing lipid rafts as evidenced by sucrose density gradient centrifugation. In nontransfected cells, endogenous caveolin-1 typically associated with low-density, detergent-resistant lipid rafts. However, transient expression of caveolin-1 Delta1-81 caused a redistribution of endogenous caveolin-1 to high-density, detergent-soluble membrane fractions. We therefore conclude that the interaction between caveolin-1 and detergent-resistant lipid rafts is an important prerequisite for endothelial VRAC activity.
小窝是由小窝蛋白与脂筏结合形成的质膜烧瓶状内陷结构。在内皮细胞中，小窝作为控制一氧化氮合成和机械转导的信号转导中心发挥作用。我们现在提供证据表明，内皮细胞容积调节性阴离子通道（VRAC）也受小窝系统的控制。当用小窝蛋白-1 Delta1-81（氨基酸1至81缺失）转染小牛肺动脉内皮（CPAE）细胞时，低渗性细胞肿胀对VRAC的激活受到严重损害。同时，如蔗糖密度梯度离心所示，小窝蛋白-1 Delta1-81干扰了含小窝蛋白-!的脂筏的形成。在未转染的细胞中，内源性小窝蛋白-1通常与低密度、抗去污剂的脂筏相关联。然而，小窝蛋白-1 Delta1-81的瞬时表达导致内源性小窝蛋白-1重新分布至高密度、可溶于去污剂的膜组分中。因此，我们得出结论，小窝蛋白-1与抗去污剂脂筏之间的相互作用是内皮细胞VRAC活性的重要前提条件。
