μ and κ opioid receptors activate ERK/MAPK via different protein kinase C isoforms and secondary messengers in astrocytes
μ and κ opioid receptors activate ERK/MAPK via different protein kinase C isoforms and secondary messengers in astrocytes
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DOI：
10.1074/jbc.m502593200
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发表时间：
2005-07-29
影响因子：
4.8
通讯作者：
Coscia, CJ
中科院分区：
文献类型：
--
作者：
Belcheva, MM;Clark, AL;Coscia, CJ
急性mu和kappa类阿片激活ERK/ MAPK磷酸化级联，这是星形胶质细胞中生长因子信号通路的一个组成部分。通过这种串扰，阿片类药物可能影响体内其他基本神经生物学过程中的神经发育和可塑性。mu激动剂[D-ala(2), mephe(4), glyol(5)]脑啡肽（DAMGO）诱导ERK磷酸化的短暂刺激，而kappa激动剂U69,593则产生持续的ERK激活。在这里，我们证明急性U69,593和DAMGO通过利用生长因子途径上游不同的次级信使和PKC异构体刺激ERK磷酸化。永生化星形胶质细胞转染反sense calmodulin (CaM)，一种与CaM结合不良的突变型mu阿片受体或PKC epsilon的显性阴性突变体作为模型系统来研究mu信号传导。有证据表明CaM和PKC epsilon与DAMGO刺激ERK有关。DAMGO激活PKC epsilon和/或ERK对Ca2+动员的选择性抑制剂不敏感，但在磷脂酶C抑制时被阻断。这些结果提示了一种新的机制，在DAMGO结合后，CaM从mu受体释放并激活磷脂酶C。随后，磷脂酶C产生激活PKC epsilon的二酰基甘油酯。相比之下，U69,593似乎通过磷酸肌肽3-激酶，PKC zeta和Ca2+动员起作用。这些信号成分与特异性抑制剂和PKC zeta显性负突变体的研究有关。总的来说，我们关于急性阿片效应的研究结果表明，它们的信号传导机制的差异可能导致慢性mu和kappa阿片样物质诱导的ERK调节的不同结果。
Acute mu and kappa opioids activate the ERK/ MAPK phosphorylation cascade that represents an integral part of the signaling pathway of growth factors in astrocytes. By this cross-talk, opioids may impact neural development and plasticity among other basic neurobiological processes in vivo. The mu agonist, [D-ala(2), mephe(4), glyol(5)] enkephalin ( DAMGO), induces a transient stimulation of ERK phosphorylation, whereas kappa agonist, U69,593, engenders sustained ERK activation. Here we demonstrate that acute U69,593 and DAMGO stimulate ERK phosphorylation by utilization of different secondary messengers and protein kinase C (PKC) isoforms upstream of the growth factor pathway. Immortalized astrocytes transfected with either antisense calmodulin (CaM), a mutant mu opioid receptor that binds CaM poorly or a dominant negative mutant of PKC epsilon were used as a model system to study mu signaling. Evidence was gained to implicate CaM and PKC epsilon in DAMGO stimulation of ERK. DAMGO activation of PKC epsilon and/or ERK was insensitive to selective inhibitors of Ca2+ mobilization, but it was blocked upon phospholipase C inhibition. These results suggest a novel mechanism wherein, upon DAMGO binding, CaM is released from the mu receptor and activates phospholipase C. Subsequently, phospholipase C generates diacylglycerides that activate PKC epsilon. In contrast, U69,593 appears to act via phosphoinositide 3-kinase, PKC zeta, and Ca2+ mobilization. These signaling components were implicated based on studies with specific inhibitors and a dominant negative mutant of PKC zeta. Collectively, our findings on acute opioid effects suggest that differences in their mechanism of signaling may contribute to the distinct outcomes on ERK modulation induced by chronic mu and kappa opioids.