Internalization and recycling of the CB1 cannabinoid receptor
Internalization and recycling of the CB1 cannabinoid receptor
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DOI：
10.1046/j.1471-4159.1999.0730493.x
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发表时间：
1999-08-01
影响因子：
4.7
通讯作者：
Mackie, K
中科院分区：
文献类型：
--
作者：
Hsieh, C;Brown, S;Mackie, K
对大麻、大麻素和作用于CBI大麻素受体的相关药物的耐受性迅速发展。然而，人们对耐受性发展过程中受体发生的变化知之甚少。在这项研究中，我们发现CB 1受体在激动剂结合和受体活化后迅速内化。有效的大麻素激动剂（WIN 55，212 -2、CP 55，940和HU 210）引起快速内化。Methanandamide（内源性大麻素anandamide的类似物）的效果较差，仅在高浓度时引起内化，而Delta（9）-四氢大麻酚即使在3 μ M时也几乎不引起内化。CB 1通过网格蛋白包被的凹陷内化为螯合被高渗蔗糖抑制。内化不需要激活G蛋白α（i）、α（o）或α（s）亚基。受体的极端羧基末端的区域对于内化是必需的，因为缺少最后14个残基的突变体CBI受体不内化，而缺少最后10个残基的突变体不内化。还研究了螯合受体再循环中涉及的步骤。恢复CB 1的细胞表面后短（20分钟），但不长（90分钟）激动剂治疗是独立的新的蛋白质合成。再循环还需要内体酸化和去磷酸化。这些结果表明，CB 1受体的运输是动态调节的拟大麻药物。
Tolerance develops rapidly to cannabis, cannabinoids, and related drugs acting at the CBI cannabinoid receptor. However, little is known about what happens to the receptor as tolerance is developing. In this study, we have found that CB1 receptors are rapidly internalized following agonist binding and receptor activation. Efficacious cannabinoid agonists (WIN 55,212-2, CP 55,940, and HU 210) caused rapid internalization. Methanandamide (an analogue of an endogenous cannabinoid, anandamide) was less effective, causing internalization only at high concentration, whereas Delta(9)-tetrahydrocannabinol caused little internalization, even at 3 mu M. CB1 internalized via clathrin-coated pits as sequestration was inhibited by hypertonic sucrose. Internalization did not require activated G protein alpha(i), alpha(o), or alpha(s) subunits. A region of the extreme carboxy terminus of the receptor was necessary for internalization, as a mutant CBI receptor lacking the last 14 residues did not internalize, whereas a mutant lacking the last 10 residues did. Steps involved in the recycling of sequestered receptor were also investigated. Recovery of CB1 to the cell surface after short (20 min) but not long (90 min) agonist treatment was independent of new protein synthesis. Recycling also required endosomal acidification and dephosphorylation. These results show that CB1 receptor trafficking is dynamically regulated by cannabimimetic drugs.