Protein kinase Cα is required for vanilloid receptor 1 activation -: Evidence for multiple signaling pathways
Protein kinase Cα is required for vanilloid receptor 1 activation -: Evidence for multiple signaling pathways
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DOI：
10.1074/jbc.m201551200
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发表时间：
2002-09-20
影响因子：
4.8
通讯作者：
Iadarola, MJ
中科院分区：
文献类型：
--
作者：
Olah, Z;Karai, L;Iadarola, MJ
在异位表达香草酸受体(VR1)的细胞和原代培养的背根神经节神经元上，观察了蛋白激酶C(PKC)对VR1的激活作用。刺激PKC的亚微摩尔佛波醇12，13-二丁酸酯(PDBu)在pH为5.5时能显著激活VR1表达细胞对钙的摄取，但在中等酸性或中性时不能。PDBu可被双吲哚马来酰亚胺(PKC)抑制剂和Ru红(VR1离子载体阻断剂)所拮抗，但不能被香草素拮抗剂卡萨西平所拮抗，表明PKC的催化活性是PDBu激活VR1离子电导所必需的，且与香草素位置无关。慢性PDBu显著下调背根神经节神经元或VR1细胞系中PKCalpha的表达，而仅部分影响PKCbeta、-β、-epsilon和Zeta。PKCalpha的丢失与对PDBu急性再攻击的反应丧失相关。阿南达胺是一种VR1激动剂，在酸性条件下与PDBu相加作用，在长期下调PKC后仍然有效。因此，可以区分出两条独立的VR1激活途径：M直接与配体结合(花青胺、香草素)或(Ii)细胞外配体通过细胞内信号与PKC偶联。在共表达VR1和不同PKC同工酶的细胞系中的实验表明，PDBu诱导的急性激活需要PKCalpha，而不需要PKCepsilon。这些研究表明，在炎症或缺血期间，感觉神经元中的PKCalpha可能会引起或增强疼痛。
Activation of vanilloid receptor (VR1) by protein kinase C (PKC) was investigated in cells ectopically expressing VR1 and primary cultures of dorsal root ganglion neurons. Submicromolar phorbol 12,13-dibutyrate (PDBu), which stimulates PKC, acutely activated Ca2+ uptake in VR1-expressing cells at pH 5.5, but not at mildly acidic or neutral pH. PDBu was antagonized by bisindolylmaleimide, a PKC inhibitor, and ruthenium red, a VR1 ionophore blocker, but not capsazepine, a vanilloid antagonist indicating that catalytic activity of PKC is required for PDBu activation of VR1 ion conductance, and is independent of the vanilloid site. Chronic PDBu dramatically down-regulated PKCalpha in dorsal root ganglion neurons or the VR1 cell lines, whereas only partially influencing PKCbeta, -delta, -epsilon, and zeta. Loss of PKCalpha correlated with loss of response to acute re-challenge with PDBu. Anandamide, a VR1 agonist in acidic conditions, acts additively with PDBu and remains effective after chronic PKC down-regulation. Thus, two independent VR1 activation pathways can be discriminated: M direct ligand binding (anandamide, vanilloids) or (ii) extracellular ligands coupled to PKC by intracellular signaling. Experiments in cell lines co-expressing VR1 with different sets of PKC isozymes showed that acute PDBu-induced activation requires PKCalpha, but not PKCepsilon. These studies suggest that PKCalpha in sensory neurons may elicit or enhance pain during inflammation or ischemia.