Koch Thomas, Wu Dai-Fei, Yang Li-Quan, Brandenburg Lars-Ove, Höllt Volker
Department of Pharmacology and Toxicology, Otto-von-Guericke University, Magdeburg, Germany.
J Neurochem. 2006 Apr;97(2):365-72. doi: 10.1111/j.1471-4159.2006.03736.x. Epub 2006 Mar 15.
We have recently shown that the mu-opioid receptor [MOR1, also termed mu-opioid peptide (MOP) receptor] is associated with the phospholipase D2 (PLD2), a phospholipid-specific phosphodiesterase located in the plasma membrane. We further demonstrated that, in human embryonic kidney (HEK) 293 cells co-expressing MOR1 and PLD2, treatment with (D-Ala2, Me Phe4, Glyol5)enkephalin (DAMGO) led to an increase in PLD2 activity and an induction of receptor endocytosis, whereas morphine, which does not induce opioid receptor endocytosis, failed to activate PLD2. In contrast, a C-terminal splice variant of the mu-opioid receptor (MOR1D, also termed MOP(1D)) exhibited robust endocytosis in response to both DAMGO and morphine treatment. We report here that MOR1D also mediates an agonist-independent (constitutive) PLD2-activation facilitating agonist-induced and constitutive receptor endocytosis. Inhibition of PLD2 activity by over-expression of a dominant negative PLD2 (nPLD2) blocked the constitutive PLD2 activation and impaired the endocytosis of MOR1D receptors. Moreover, we provide evidence that the endocytotic trafficking of the delta-opioid receptor [DOR, also termed delta-opioid peptide (DOP) receptor] and cannabinoid receptor isoform 1 (CB1) is also mediated by a PLD2-dependent pathway. These data indicate the generally important role for PLD2 in the regulation of agonist-dependent and agonist-independent G protein-coupled receptor (GPCR) endocytosis.
我们最近发现，μ-阿片受体[MOR1，也称为μ-阿片肽（MOP）受体]与磷脂酶D2（PLD2）相关，PLD2是一种位于质膜的磷脂特异性磷酸二酯酶。我们进一步证明，在共表达MOR1和PLD2的人胚肾（HEK）293细胞中，用（D-丙氨酸2，甲基苯丙氨酸4，甘醇5）脑啡肽（DAMGO）处理会导致PLD2活性增加并诱导受体内吞作用，而吗啡不会诱导阿片受体的内吞作用，无法激活PLD2。相比之下，μ-阿片受体的C末端剪接变体（MOR1D，也称为MOP(1D)）在DAMGO和吗啡处理后均表现出强烈的内吞作用。我们在此报告，MOR1D还介导了一种不依赖激动剂的（组成性）PLD2激活，促进激动剂诱导的组成性受体内吞作用。通过过表达显性负性PLD2（nPLD2）抑制PLD2活性可阻断组成性PLD2激活并损害MOR1D受体的内吞作用。此外，我们提供证据表明，δ-阿片受体[DOR，也称为δ-阿片肽（DOP）受体]和大麻素受体亚型1（CB1）的内吞运输也由PLD2依赖性途径介导。这些数据表明PLD2在调节激动剂依赖性和激动剂非依赖性G蛋白偶联受体（GPCR）内吞作用中具有普遍重要的作用。
