Rajasekhar Pradeep, Poole Daniel P, Liedtke Wolfgang, Bunnett Nigel W, Veldhuis Nicholas A
From the Monash Institute of Pharmaceutical Sciences, Australian Research Council Centre of Excellence in Convergent Bio-Nano Science and Technology, and.
From the Monash Institute of Pharmaceutical Sciences, Australian Research Council Centre of Excellence in Convergent Bio-Nano Science and Technology, and the Departments of Anatomy and Neuroscience.
J Biol Chem. 2015 Nov 27;290(48):29051-62. doi: 10.1074/jbc.M115.689729. Epub 2015 Oct 16.
Transient receptor potential (TRP) ion channels of peripheral sensory pathways are important mediators of pain, itch, and neurogenic inflammation. They are expressed by primary sensory neurons and by glial cells in the central nervous system, but their expression and function in satellite glial cells (SGCs) of sensory ganglia have not been explored. SGCs tightly ensheath neurons of sensory ganglia and can regulate neuronal excitability in pain and inflammatory states. Using a modified dissociation protocol, we isolated neurons with attached SGCs from dorsal root ganglia of mice. SGCs, which were identified by expression of immunoreactive Kir4.1 and glutamine synthetase, were closely associated with neurons, identified using the pan-neuronal marker NeuN. A subpopulation of SGCs expressed immunoreactive TRP vanilloid 4 (TRPV4) and responded to the TRPV4-selective agonist GSK1016790A by an influx of Ca(2+) ions. SGCs did not express functional TRPV1, TRPV3, or TRP ankyrin 1 channels. Responses to GSK1016790A were abolished by the TRPV4 antagonist HC067047 and were absent in SGCs from Trpv4(-/-) mice. The P2Y1-selective agonist 2-methylthio-ADP increased [Ca(2+)]i in SGCs, and responses were prevented by the P2Y1-selective antagonist MRS2500. P2Y1 receptor-mediated responses were enhanced in TRPV4-expressing SGCs and HEK293 cells, suggesting that P2Y1 couples to and activates TRPV4. PKC inhibitors prevented P2Y1 receptor activation of TRPV4. Our results provide the first evidence for expression of TRPV4 in SGCs and demonstrate that TRPV4 is a purinergic receptor-operated channel in SGCs of sensory ganglia.
外周感觉通路的瞬时受体电位（TRP）离子通道是疼痛、瘙痒和神经源性炎症的重要介质。它们由初级感觉神经元和中枢神经系统中的胶质细胞表达，但尚未研究其在感觉神经节卫星胶质细胞（SGC）中的表达和功能。SGC紧密包裹感觉神经节的神经元，并可在疼痛和炎症状态下调节神经元兴奋性。使用改良的解离方案，我们从小鼠背根神经节中分离出带有附着SGC的神经元。通过免疫反应性Kir4.1和谷氨酰胺合成酶的表达鉴定的SGC与使用泛神经元标记物NeuN鉴定的神经元密切相关。SGC的一个亚群表达免疫反应性TRP香草酸受体4（TRPV4），并通过Ca(2+)离子内流对TRPV4选择性激动剂GSK1016790A作出反应。SGC不表达功能性TRPV1、TRPV3或TRP锚蛋白1通道。对GSK1016790A的反应被TRPV4拮抗剂HC067047消除，并且在Trpv4(-/-)小鼠的SGC中不存在。P2Y1选择性激动剂2-甲基硫代-ADP增加SGC中的[Ca(2+)]i，并且反应被P2Y1选择性拮抗剂MRS2500阻止。P2Y1受体介导的反应在表达TRPV4的SGC和HEK293细胞中增强，表明P2Y1与TRPV4偶联并激活TRPV4。PKC抑制剂阻止P2Y1受体对TRPV4的激活。我们的结果为TRPV4在SGC中的表达提供了首个证据，并证明TRPV4是感觉神经节SGC中的嘌呤能受体操纵通道。
