Mangoura D
Department of Pediatrics, University of Chicago, IL 60637, USA.
J Neurosci Res. 1997 Nov 1;50(3):391-401. doi: 10.1002/(SICI)1097-4547(19971101)50:3<391::AID-JNR5>3.0.CO;2-D.
We have investigated the signal transduction pathway of the G-protein mu-opioid receptor upstream of phospholipase D (PLD) and protein kinase C-epsilon (PKC-epsilon) activation in postmitotic E6CH chick embryo cortical neurons. The mu-opioid receptor and PLD-PKC-epsilon functional coupling depends on upstream tyrosine kinase activation. We now report that the mu-opioid agonists specifically stimulated tyrosine phosphorylation and activation of the focal adhesion kinase (FAK) in a time-dependent manner. We also demonstrate that met-enkephalin, a mu-opioid agonist in E6CH cultures, significantly increases tyrosine phosphorylation of another Src kinase substrate, the cytoskeletal protein cortactin. Tyrosine phosphorylation of cortactin led to drastic changes in subcellular localization, an estimated 2-fold enrichment in the cytosol. Similarly, opioids stimulated a sustained tyrosine phosphorylation of vinculin, a protein enriched in focal adhesion sites. These data provide novel evidence that opioid receptor intracellular signaling engages the specific activation of tyrosine kinase FAK and regulates the neuronal cytoskeleton during central nervous system morphogenesis.
我们研究了有丝分裂后E6CH鸡胚皮质神经元中，磷脂酶D（PLD）和蛋白激酶C-ε（PKC-ε）激活上游的G蛋白μ-阿片受体的信号转导途径。μ-阿片受体与PLD-PKC-ε的功能偶联依赖于上游酪氨酸激酶的激活。我们现在报告，μ-阿片激动剂以时间依赖性方式特异性刺激粘着斑激酶（FAK）的酪氨酸磷酸化和激活。我们还证明，E6CH培养物中的μ-阿片激动剂甲硫氨酸脑啡肽，显著增加另一种Src激酶底物——细胞骨架蛋白皮层肌动蛋白的酪氨酸磷酸化。皮层肌动蛋白的酪氨酸磷酸化导致亚细胞定位发生剧烈变化，胞质溶胶中估计富集了2倍。同样，阿片类药物刺激了粘着斑蛋白（一种富集于粘着斑部位的蛋白质）的持续酪氨酸磷酸化。这些数据提供了新的证据，表明阿片受体细胞内信号传导参与酪氨酸激酶FAK的特异性激活，并在中枢神经系统形态发生过程中调节神经元细胞骨架。
