β-Adrenergic receptor trafficking by exercise in rat adipocytes: roles of G-protein-coupled receptor kinase-2, β-arrestin-2, and the ubiquitin-proteasome pathway
β-Adrenergic receptor trafficking by exercise in rat adipocytes: roles of G-protein-coupled receptor kinase-2, β-arrestin-2, and the ubiquitin-proteasome pathway
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DOI：
10.1096/fj.05-4688fje
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发表时间：
2006-02-01
期刊：
影响因子：
4.8
通讯作者：
Izawa, Tetsuya
中科院分区：
文献类型：
--
作者：
Ogasawara, Junetsu;Sanpei, Minori;Izawa, Tetsuya
在大鼠脂肪细胞中研究了运动对β-肾上腺素能受体（β-AR）运输的影响。亲水性配体[3 H] CGP 12177的结合位点在运动后即刻（0 h）和3 h（3 h）增加，但在运动后24 h（24 h）减少。免疫印迹结果显示，结合位点的改变主要影响膜组分中β2-AR蛋白的改变。G蛋白偶联受体激酶（GRK）-2和β-arrestin-2的蛋白表达均降低，0 h和3 h时β2-AR泛素化水平下降。在24 h时，β2-AR、GRK-2、β-arrestin-2、β2-AR/β-arrestin-2复合物和β2-AR泛素化的蛋白表达恢复至各自的对照水平，而β2-AR mRNA水平降低。给予lactacystin或普萘洛尔并没有改变运动后GRK-2和β2-AR蛋白的表达。因此，β2-AR密度增加至少3 h的潜在机制可能涉及多步骤事件的改变，该事件涉及介导β2-AR运输的蛋白质之间的协调相互作用，其中受体-激动剂相互作用和泛素-蛋白酶体途径都具有关键作用。然而，24 h时β2-AR蛋白表达的降低可能是由于翻译水平发生了一些变化。
The effect of exercise on β‐adrenergic receptor (β‐AR) trafficking was investigated in rat adipocytes. The binding sites of a hydrophilic ligand, [3H]CGP12177, increased immediately (0 h) and at 3 h after exercise (3 h) but decreased at 24 h after exercise (24 h). The data of immunoblotting revealed that the alterations in the binding sites mainly paralleled the alterations in the β2‐AR proteins in membrane fractions. The protein expressions of both G‐protein‐coupled receptor kinase (GRK)‐2 and β‐arrestin‐2 were reduced, with a decline in β2‐AR ubiquitination at 0 h and 3 h. The protein expressions of β2‐AR, GRK‐2, β‐arrestin‐2, the β2‐AR/β‐arrestin‐2 complex, and β2‐AR ubiquitination returned to their respective control levels at 24 h, whereas the β2‐AR mRNA level was reduced. Administration of either lactacystin or propranolol did not alter GRK‐2 and β2‐AR protein expressions after exercise. Thus, the mechanism underlying the increased density of β2‐AR up to at least 3 h may involve alterations in a multistep event involving the coordinate interaction among proteins mediating β2‐AR trafficking, in which both the receptor‐agonist interactions and ubiquitin‐proteasome pathway have a key role. However, the decreased protein expression of β2‐AR at 24 h might be due to some change occurring at the translational levels.