Chiu Yi-Ting, Chen Chongguang, Yu Daohai, Schulz Stefan, Liu-Chen Lee-Yuan
Center for Substance Abuse Research and Department of Pharmacology (Y.-T.C., C.C., L.-Y.L.-C.) and Department of Clinical Sciences (D.Y.), Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania; and Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, Jena, Germany (S.S.).
Center for Substance Abuse Research and Department of Pharmacology (Y.-T.C., C.C., L.-Y.L.-C.) and Department of Clinical Sciences (D.Y.), Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania; and Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, Jena, Germany (S.S.)
Mol Pharmacol. 2017 Nov;92(5):588-600. doi: 10.1124/mol.117.108555. Epub 2017 Sep 11.
We reported previously that the selective agonist U50,488H promoted phosphorylation of the mouse κ opioid receptor (KOPR) at residues S356, T357, T363, and S369. Here, we found that agonist (U50,488H)-dependent KOPR phosphorylation at all the residues was mediated by Gi/o proteins and multiple protein kinases [GRK2, GRK3, GRK5, GRK6 and protein kinase C (PKC)]. In addition, PKC activation by phorbol ester induced agonist-independent KOPR phosphorylation. Compared with U50,488H, PKC activation promoted much higher S356/T357 phosphorylation, much lower T363 phosphorylation, and similar levels of S369 phosphorylation. After U50,488H treatment, GRKs, but not PKC, were involved in agonist-induced KOPR internalization. In contrast, PKC activation caused a lower level of agonist-independent KOPR internalization, compared with U50,488H. U50,488H-induced activation of extracellular signal-regulated kinase 1/2 (ERK1/2) was G protein-, but not -arrestin-, dependent. After U50,488H treatment, GRK-mediated, but not PKC-mediated, KOPR phosphorylation followed by -arrestin recruitment desensitized U50,488H-induced ERK1/2 response. Therefore, agonist-dependent (GRK- and PKC-mediated) and agonist-independent (PKC-promoted) KOPR phosphorylations show distinct phosphorylation patterns, leading to diverse cellular outcomes.
我们之前报道过，选择性激动剂U50,488H可促进小鼠κ阿片受体（KOPR）在S356、T357、T363和S369位点的磷酸化。在此，我们发现所有位点上激动剂（U50,488H）依赖性的KOPR磷酸化是由Gi/o蛋白和多种蛋白激酶[GRK2、GRK3、GRK5、GRK6和蛋白激酶C（PKC）]介导的。此外，佛波酯激活PKC可诱导非激动剂依赖性的KOPR磷酸化。与U50,488H相比，PKC激活促进的S356/T357磷酸化水平更高，T363磷酸化水平更低，而S369磷酸化水平相似。U50,488H处理后，GRK而非PKC参与激动剂诱导的KOPR内化。相反，与U50,488H相比，PKC激活导致的非激动剂依赖性KOPR内化水平较低。U50,488H诱导的细胞外信号调节激酶1/2（ERK1/2）激活依赖于G蛋白，而非β-抑制蛋白。U50,488H处理后，GRK介导而非PKC介导的KOPR磷酸化随后募集β-抑制蛋白使U50,488H诱导的ERK1/2反应脱敏。因此，激动剂依赖性（GRK和PKC介导）和激动剂非依赖性（PKC促进）的KOPR磷酸化表现出不同的磷酸化模式，导致不同的细胞结果。
