Cholesterol-dependent regulation of adenosine A2A receptor-mediated anion secretion in colon epithelial cells
Cholesterol-dependent regulation of adenosine A2A receptor-mediated anion secretion in colon epithelial cells
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DOI：
10.1016/j.yexcr.2009.06.005
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发表时间：
2009-10-15
影响因子：
3.7
通讯作者：
Duszyk, Marek
中科院分区：
文献类型：
--
作者：
Lam, Rebecca S.;Nahirney, Drew;Duszyk, Marek
胆固醇影响多种生物过程，在许多情况下通过调节整体膜蛋白的功能。在这项研究中，我们研究了胆固醇在结肠上皮细胞中腺苷依赖的离子转运调节中的作用。我们观察到甲基- β -环糊精（M β - CD），一种胆固醇隔离分子，增强腺苷a （2A）受体激活的经上皮短路电流（I-sc），但仅从基底外侧。胆固醇是膜微域的主要组成部分，称为脂筏，也含有鞘脂。然而，鞘磷脂降解酶鞘磷脂酶和胆固醇结合剂filipin的研究表明，仅胆固醇水平的变化就足以控制腺苷调节的I-sc。胆固醇消耗对a （2A）受体的功能选择性有重要影响。在对照条件下，腺苷比特定的A（2A）激动剂CGS-21680更有效地激活I-sc，并且电流被XE991 （camp依赖性K+通道抑制剂）抑制。在胆固醇消耗后，CGS-21680比腺苷更有效地激活I-sc，并且电流被氯霉唑（一种Ca2+激活的K+ (IK1)通道抑制剂）抑制。共亚胺沉淀实验显示，胆固醇消耗后，A（2A）受体与IK1通道相关。这些结果表明，结肠上皮中的胆固醇含量通过控制激动剂选择性信号传导影响腺苷介导的阴离子分泌。(C) 2009爱思唯尔公司版权所有。
Cholesterol affects diverse biological processes, in many cases by modulating the function of integral membrane proteins. In this study we have investigated the role of cholesterol in the adenosine-dependent regulation of ion transport in colonic epithelial cells. We observed that methyl-beta-cyclodextrin (M beta CD), a cholesterol-sequestering molecule, enhanced adenosine A(2A) receptor-activated transepithelial short circuit Current (I-sc), but only from the basolateral side. Cholesterol is a major constituent of membrane microdomains, called lipid rafts that also contain sphingolipids. However, studies with the sphingomyelin-degrading enzyme, sphingomyelinase, and the cholesterol-binding agent, filipin, indicated that the change in the level of cholesterol alone was sufficient to control the adenosine-modulated I-sc. Cholesterol depletion had a major effect on the functional selectivity of A(2A) receptors. Under control conditions, adenosine activated I-sc more potently than the specific A(2A) agonist, CGS-21680, and the current was inhibited by XE991, an inhibitor of cAMP-dependent K+ channels. Following cholesterol depletion, CGS-21680 activated I-sc more potently than adenosine, and the current was inhibited by clotrimazole, an inhibitor of Ca2+-activated K+ (IK1) channels. Co-iminunoprecipitation experiments revealed that A(2A) receptors associate with IK1 channels following cholesterol depletion. These results suggest that cholesterol content in colonic epithelia affects adenosine-mediated anion secretion by controlling agonist-selective signaling. (C) 2009 Elsevier Inc. All rights reserved.