Fast Modulation of μ-Opioid Receptor (MOR) Recycling Is Mediated by Receptor Agonists
Fast Modulation of μ-Opioid Receptor (MOR) Recycling Is Mediated by Receptor Agonists
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DOI：
10.1074/jbc.m111.319616
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发表时间：
2012-04-27
影响因子：
4.8
通讯作者：
Yudowski, Guillermo Ariel
中科院分区：
文献类型：
--
作者：
Roman-Vendrell, Cristina;Yu, Y. Joy;Yudowski, Guillermo Ariel
mu-阿片受体（MOR）是G蛋白偶联受体家族的成员，是内源性阿片神经肽和吗啡的主要靶标。被配体激活后，MOR 通过异源细胞和分离的纹状体神经元中网格蛋白包被的凹坑快速内化。初始内吞作用后，重新敏化的受体通过囊泡递送再循环回细胞表面，以进行后续的激活周期。 MOR 贩运与急性暴露于激动剂后的阿片类药物耐受性有关，但它也参与了重新敏化过程。一些研究描述了 MOR 内吞作用的调节和机制，但对细胞表面重新敏化受体的再循环知之甚少。为了研究这一过程，我们用 [D-Ala(2)、N-Me-Phe(4)、Gly(5)-ol]-脑啡肽 (DAMGO) 和吗啡诱导 MOR 内化，并对将受体回收到细胞表面的单囊泡进行实时成像。我们确定了单个囊泡的回收动力学和其中包含的受体的数量。然后我们证明了回收 MOR 到细胞表面的快速囊泡递送是由肌动蛋白-微管细胞骨架介导的。回收还依赖于 Rab4、Rab11 和 Ca2+ 敏感运动蛋白肌球蛋白 Vb。最后，我们表明，激动剂的存在和 cAMP 水平会强烈调节再循环。我们的工作确定了一种新的运输机制，该机制可以在急性激动剂暴露期间增加细胞表面 MOR 的数量，从而有效减少阿片类药物耐受性的发展。
The mu-opioid receptor (MOR) is a member of the G protein-coupled receptor family and the main target of endogenous opioid neuropeptides and morphine. Upon activation by ligands, MORs are rapidly internalized via clathrin-coated pits in heterologous cells and dissociated striatal neurons. After initial endocytosis, resensitized receptors recycle back to the cell surface by vesicular delivery for subsequent cycles of activation. MOR trafficking has been linked to opioid tolerance after acute exposure to agonist, but it is also involved in the resensitization process. Several studies describe the regulation and mechanism of MOR endocytosis, but little is known about the recycling of resensitized receptors to the cell surface. To study this process, we induced internalization of MOR with [D-Ala(2), N-Me-Phe(4), Gly(5)-ol]-enkephalin (DAMGO) and morphine and imaged in real time single vesicles recycling receptors to the cell surface. We determined single vesicle recycling kinetics and the number of receptors contained in them. Then we demonstrated that rapid vesicular delivery of recycling MORs to the cell surface was mediated by the actin-microtubule cytoskeleton. Recycling was also dependent on Rab4, Rab11, and the Ca2+-sensitive motor protein myosin Vb. Finally, we showed that recycling is acutely modulated by the presence of agonists and the levels of cAMP. Our work identifies a novel trafficking mechanism that increases the number of cell surface MORs during acute agonist exposure, effectively reducing the development of opioid tolerance.