Enhancement of potency and efficacy of NADA by PKC-mediated phosphorylation of vanilloid receptor.
Enhancement of potency and efficacy of NADA by PKC-mediated phosphorylation of vanilloid receptor.
复制标题
通过 PKC 介导的香草酸受体磷酸化增强 NADA 的效力和功效。
DOI：
10.1152/jn.00745.2003
复制
发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Raisinghani,Manish
中科院分区：
文献类型：
--
作者：
Premkumar,LouisS;Qi,Zhan-Heng;VanBuren,Jeremy;Raisinghani,Manish
The search for an endogenous ligand for the vanilloid receptor (VR or TRPV1) has led to the identification ofN-arachidonyl dopamine (NADA). This study investigates the role of protein kinase C (PKC)-mediated phosphorylation on NADA-induced membrane currents inXenopusoocytes heterologously expressing TRPV1 and in dorsal root ganglion (DRG) neurons. In basal state, current induced by 10 μM NADA is 5-10% of the current induced by 1 μM capsaicin or protons at pH 5. However, PKC activator, phorbol 12,13-dibutyrate (PDBu) strongly potentiated (∼15-fold) the NADA-induced current. Repeated application of NADA at short intervals potentiated its own response approximately fivefold in a PKC-dependent manner. PKC inhibitor, bisindolylmaleimide (BIM, 500 nM), a mutant TRPV1 (S800A/S502A), and maximal activation of PKC abolished the potentiation induced by repeated application of NADA. As a further confirmation that NADA could stimulate PKC, pretreatment with NADA potentiated the response of protons at pH 5 (∼20 fold), which was dramatically reduced in the mutant TRPV1. In DRG neurons, capsaicin (100 nM) induced a ∼15 mV depolarization and initiated a train of action potentials compared with 1 μM NADA that produced a ∼5 mV response. Pretreatment with PDBu induced significantly larger depolarization and potentiated NADA-induced current. Furthermore, exposure of NADA to the intracellular surface of the membrane-induced larger currents suggesting inaccessibility to the intracellular binding site might contribute to its weaker action. These results indicate that NADA is a potent agonist of VR when the receptor is in the PKC-mediated phosphorylation state.
