The metabotropic glutamate receptor mGluR5 is endocytosed by a clathrin-independent pathway
The metabotropic glutamate receptor mGluR5 is endocytosed by a clathrin-independent pathway
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DOI：
10.1074/jbc.m205663200
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发表时间：
2003-04-04
影响因子：
4.8
通讯作者：
Hémar, A
中科院分区：
文献类型：
--
作者：
Fourgeaud, L;Bessis, AS;Hémar, A
代谢性谷氨酸受体5 （mGluR5）是生长组C G蛋白偶联受体家族的成员。它们在哺乳动物大脑中广泛表达，参与谷氨酸传递的调节。通过将mGluR5受体转染到培养的cox -7细胞和海马原代神经元中，然后进行免疫细胞化学和定量图像分析以及生化分析，我们研究了mGluR5剪接变异体的内化。mGluR5a和-5b在COS-7细胞以及培养神经元的轴突和树突中被内吞。即使在没有受体活性的情况下，也会发生内吞作用，因为在谷氨酸结合位点突变的受体以及内源性活性被逆激动剂抑制的受体仍然被内化。我们测量了mGluR5a的内吞作用构成率为11.7%/min。我们首次报道了mGluR5的内吞途径。mGluR5的内化不是由网格蛋白包覆的凹坑介导的。事实上，Eps15显性阴性突变体对这一途径的抑制并不会干扰它们的内吞作用。然而，大的GTPase动力蛋白2与COS-7中mGluR5的内吞作用有关。mGluR5是C组g蛋白偶联受体家族中第一个通过非常规途径内化的成员。
Metabotropic glutamate receptors 5 (mGluR5) are members of the growing group C G protein-coupled receptor family. Widely expressed in mammalian brain, they are involved in modulation of the glutamate transmission. By means of transfection of mGluR5 receptors in COS-7 cells and primary hippocampal neurons in culture followed by immunocytochemistry and quantitative image analysis and by a biochemical assay, we have studied the internalization of mGluR5 splice variants. mGluR5a and -5b were endocytosed in COS-7 cells as well as in axons and dendrites of cultured neurons. Endocytosis occurred even in the absence of receptor activity, because receptors mutated in the glutamate binding site were still internalized as well as receptors in which endogenous activity had been inhibited by an inverse agonist. We have measured a constitutive rate of endocytosis of 11.7%/min for mGluR5a. We report for the first time the endocytosis pathway of mGluR5. Internalization of mGluR5 is not mediated by clathrin-coated pits. Indeed, inhibition of this pathway by Eps15 dominant negative mutants did not disturb their endocytosis. However, the large GTPase dynamin 2 is implicated in the endocytosis of mGluR5 in COS-7. mGluR5 is the first shown member of the group C G-protein coupled receptor family internalized by a nonconventional pathway.