Inhibition of P2X4 Function by P2Y6 UDP Receptors in Microglia
Inhibition of P2X4 Function by P2Y6 UDP Receptors in Microglia
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DOI：
10.1002/glia.22574
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发表时间：
2013-12-01
期刊：
影响因子：
6.2
通讯作者：
Seguela, Philippe
中科院分区：
文献类型：
--
作者：
Bernier, Louis-Philippe;Ase, Ariel R.;Seguela, Philippe
脊髓小胶质细胞表达的ATP门控的P2X4受体通道积极参与中枢敏化，使其功能调节成为慢性疼痛病理过程中的一个关键过程。P2Y6代谢G(Q)偶联受体也表达在小胶质细胞中，参与神经损伤的初始反应，在被UDP激活后触发吞噬作用。最近有报道称，神经损伤后活化的小胶质细胞中P2X4和P2Y6的表达均上调。我们发现，在静息和脂多糖激活的原代小胶质细胞中，通过Yo-Pro-1摄取实验，P2Y6减少了P2X4介导的钙内流，并抑制了P2X4通道进入大电导孔的扩张。此外，P2Y6的激活调节了小胶质细胞依赖于ATP的迁移，这一过程可能参与了小胶质细胞从迁移表型向吞噬表型的转变。重组体系中P2X4-P2Y6相互作用的重构表明，P2Y6的激活降低了P2X4电流的幅度、激活和脱敏速率，降低了大阳离子NMDG(+)对P2X4通道的通透性。磷脂酶C介导的磷脂酰肌醇PI(4，5)P-2的水解是P2X4通道功能所必需的辅助因子，是抑制串扰的基础。随着神经损伤后脊髓细胞外ATP和UDP水平的升高，P2Y6对P2X4活性的调控可能在调节神经病理性疼痛诱导的小胶质细胞反应中发挥关键作用。
ATP-gated P2X4 receptor channels expressed in spinal microglia actively participate in central sensitization, making their functional regulation a key process in chronic pain pathologies. P2Y6 metabotropic G(q)-coupled receptors, also expressed in microglia, are involved in the initial response to nerve injury, triggering phagocytosis upon activation by UDP. It has been reported recently that expression of both P2X4 and P2Y6 is upregulated in activated microglia following nerve injury. We show here, in resting as well as LPS-activated primary microglia, that P2Y6 decreases P2X4-mediated calcium entry and inhibits the dilation of P2X4 channels into a large-conductance pore measured with a YO-PRO-1 uptake assay. Furthermore, P2Y6 activation modulates the ATP-dependent migration of microglia, a process likely involved in their shift from migratory to phagocytic phenotype. Reconstituting the P2X4-P2Y6 interaction in recombinant systems shows that P2Y6 activation decreases P2X4 current amplitude, activation and desensitization rates, and reduces P2X4 channel permeability to the large cation NMDG(+). Phospholipase C-mediated hydrolysis of the phosphoinositide PI(4,5)P-2, a necessary cofactor for P2X4 channel function, underlies this inhibitory crosstalk. As extracellular levels of both ATP and UDP are increased in the spinal cord following nerve injury, the control of P2X4 activity by P2Y6 might play a critical role in regulating neuropathic pain-inducing microglial responses.