Internalization and Src activity regulate the time course of ERK activation by delta opioid receptor ligands
Internalization and Src activity regulate the time course of ERK activation by delta opioid receptor ligands
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DOI：
10.1074/jbc.m411695200
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发表时间：
2005-03-04
影响因子：
4.8
通讯作者：
Piñeyro, G
中科院分区：
文献类型：
--
作者：
Audet, N;Paquin-Gobeil, M;Piñeyro, G
本研究表明，δ阿片受体 (deltaOR) 配体 Tyr-Ticpsi [CH2-NH] Cha-Phe-OH (TICP) 和 ICI174864 在环化酶途径中充当反向激动剂，但在 ERK 级联中诱导激动剂反应。与在两条途径中充当激动剂且对 ERK 的刺激是显着但短暂的（10 分钟）的配体不同，ICI174864 和 TICP 的 ERK 激活是中等且持续的，在 TICP 的情况下持续超过 1 小时。生化实验表明，激动剂和“双效配体”激活ERK的持续时间与其触发受体磷酸化和降解的能力呈负相关。因此，虽然 TICP 将 deltaOR 稳定在不掺入 P-32 的构象中，不是酪氨酸激酶 Src 的底物，并且在长时间暴露于药物后不会下调，但由掺入 P-32 的 D-Pen-2,5-脑啡肽 (DPDPE) 稳定的构象被 Src 磷酸化，并在治疗的前 2 小时内发生降解。蔗糖对内吞作用的抑制延长了 DPDPE 的 ERK 激活，增加了响应的衰减半衰期，达到类似于双效配体的值（从 2 分钟衰减 t(1/2) 增加到 12 分钟）。 Src 抑制剂 PP2 还延长了 DPDPE 的 ERK 刺激时间。它是通过在最初的反应迅速降低后将激酶的持续激活维持在最大激活值的 20% 左右来实现的。这些结果表明，激动剂和双重功效配体激活 ERK 的特定动力学至少部分是由两类药物触发调节 deltaOR 反应性机制的差异能力决定的。
The present study showed that delta opioid receptor (deltaOR) ligands Tyr-Ticpsi [CH2-NH] Cha-Phe-OH (TICP) and ICI174864 behaved as inverse agonists in the cyclase pathway but induced agonist responses in the ERK cascade. Unlike ligands that behaved as agonists in both pathways, and whose stimulation of ERK was marked but transient (10 min), ERK activation by ICI174864 and TICP was moderate and sustained, lasting for more than 1 h in the case of TICP. Biochemical experiments showed that duration of ERK activation by agonists and "dual efficacy ligands" was inversely correlated with their ability to trigger receptor phosphorylation and degradation. Thus, although TICP stabilized deltaORs in a conformation that did not incorporate P-32, was not a substrate for tyrosine kinase Src, and was not downregulated following prolonged exposure to the drug, the conformation stabilized by D-Pen-2,5-enkephalin (DPDPE) incorporated P-32, was phosphorylated by Src, and suffered degradation within the first 2 h of treatment. Inhibition of endocytosis by sucrose prolonged ERK activation by DPDPE increasing the decay half-life of the response to values that resembled those of dual efficacy ligands (from a 2-min decay t(1/2) increased to 12 min). Src inhibitor PP2 also prolonged ERK stimulation by DPDPE. It did so by maintaining a sustained activation of the kinase at similar to20% of maximum following an initial rapid reduction in the response. These results show that specific kinetics of ERK activation by agonists and dual efficacy ligands are determined, at least in part, by the differential ability of the two types of drugs to trigger mechanisms regulating deltaOR responsiveness.