Agonist-mediated endocytosis of rat somatostatin receptor subtype 3 involves β-arrestin and clathrin coated vesicles
Agonist-mediated endocytosis of rat somatostatin receptor subtype 3 involves β-arrestin and clathrin coated vesicles
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DOI：
10.1046/j.1365-2826.2001.00630.x
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发表时间：
2001-03-01
影响因子：
3.2
通讯作者：
Meyerhof, W
中科院分区：
文献类型：
--
作者：
Kreuzer, OJ;Krisch, B;Meyerhof, W
促生长素抑制素受体激动剂诱导的内吞作用决定了随后细胞对肽激动剂的反应性，并影响促生长素抑制素受体显像，这是一种对各种肿瘤进行成像的技术。我们研究了在转染的大鼠神经内分泌胰岛素瘤细胞中，表位标记的3型生长抑素受体sst 3 HSV的内化。用生长抑素刺激这些细胞诱导共表达的增强型绿色荧光蛋白/β-抑制蛋白1融合蛋白和sst 3 HSV的运输，以共定位在相同的内吞囊泡中。抑制蛋白融合蛋白的显性负突变体与受体的共表达阻断了Sst 3 HSV的内化。用生长抑素刺激还诱导α-适应素（衔接蛋白复合物2的组分）瞬时易位至质膜，α-适应素和网格蛋白与受体共定位。通过电子显微镜，我们观察到内化的SST 3在网格蛋白包被的小坑，内体和多泡体的限制膜，一个典型的受体被回收的位置。一致地，我们观察到sst 3 HSV与Rab 11共定位在核周区室中，这可能对应于核周再循环内体。因此，激动剂诱导的sst 3的内吞作用取决于其与B-抑制蛋白的相互作用，涉及衔接蛋白复合物2，并通过网格蛋白包被的囊泡进行再循环室。
Agonist-induced endocytosis of somatostatin receptors determines subsequent cellular responsiveness to peptide agonist and influences somatostatin receptor scintigraphy, a technique to image various tumours. We examined the internalization of sst3HSV, an epitope-tagged type 3 somatostatin receptor, in transfected rat neuroendocrine insulinoma cells. Stimulation of these cells with somatostatin induced trafficking of coexpressed enhanced green fluorescence protein/beta -arrestin 1 fusion protein and sst3HSV to colocalize in the same endocytic vesicles. Coexpression of a dominant negative mutant of the arrestin fusion protein with the receptor blocked the internalization of sst3HSV. Stimulation with somatostatin also induced the transient translocation of alpha -adaptin, a component of the adaptor protein complex 2, to the plasma membrane, alpha -adaptin and clathrin colocalized with the receptor. By electron microscopy, we observed internalized sst3 in clathrin coated pits, endosomes and at the limiting membrane of multivesicular bodies, a location typical for receptors being recycled. Concordantly, we observed sst3HSV colocalized with Rab11 in a perinuclear compartment which is likely to correspond to the pericentriolar recycling endosome. Thus, agonist-induced endocytosis of sst3 depends on its interaction with B-arrestin, involves the adaptor protein complex 2 and proceeds via clathrin coated vesicles to the recycling compartment.