The nucleotide receptor P2RX7 mediates ATP-induced CREB activation in human and murine monocytic cells
The nucleotide receptor P2RX7 mediates ATP-induced CREB activation in human and murine monocytic cells
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DOI：
10.1189/jlb.0907612
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发表时间：
2008-10-01
影响因子：
5.5
通讯作者：
Bertics, Paul J.
中科院分区：
文献类型：
--
作者：
Gavala, Monica L.;Pfeiffer, Zachary A.;Bertics, Paul J.
核苷酸受体是细胞外三磷酸腺苷的感受器，对免疫功能具有重要作用。核苷酸受体P2RX7是一种细胞表面、配体门控的阳离子通道，与许多疾病有关，包括关节炎、肉芽肿形成、脓毒症和结核病。炎症微环境中活化的巨噬细胞过度释放介质往往会加重这些疾病。虽然P2RX7的激活可以调节单核/巨噬细胞诱导的炎症事件，但相关的分子机制尚不清楚。先前的研究表明，MAPK的级联和转录调控通过CREB连接的途径调节单核细胞的炎症能力。由于P2RX7促进MAPK活化和炎症介质的产生，我们研究了MAPK诱导的CREB激活在P2RX7作用中的作用。我们的数据显示，用P2RX7激动剂刺激多个单核细胞系可诱导CREB快速磷酸化。此外，我们观察到，在表达无功能的P2RX7的RAW 264.7细胞中，缺乏核苷酸诱导的CREB磷酸化，而在异源表达人P2RX7的人胚胎肾293细胞中，核苷酸诱导的CREB磷酸化有所增加。此外，我们的结果表明，P2RX7激动剂诱导的CREB磷酸化部分是通过钙离子通量和MEK/ERK系统来调节的。机制分析表明，用P2RX7激动剂刺激巨噬细胞可诱导CREB/CREB结合蛋白复合体的形成，这是CREB转录激活所必需的。此外，我们还证明了P2RX7激活诱导了一个已知的CREB依赖基因(c-fos)，而显性负CREB结构减弱了这一反应。这些研究支持这样一种观点，即P2RX7刺激可以直接调节蛋白质的表达，而不依赖于与其他免疫调节剂如脂多糖的共刺激。
Nucleotide receptors serve as sensors of extracellular ATP and are important for immune function. The nucleotide receptor P2RX7 is a cell-surface, ligand-gated cation channel that has been implicated in many diseases, including arthritis, granuloma formation, sepsis, and tuberculosis. These disorders are often exacerbated by excessive mediator release from activated macrophages in the inflammatory microenvironment. Although P2RX7 activation can modulate monocyte/macrophage-induced inflammatory events, the relevant molecular mechanisms are poorly understood. Previous studies suggest that MAPK cascades and transcriptional control via CREB-linked pathways regulate the inflammatory capacity of monocytic cells. As P2RX7 promotes MAPK activation and inflammatory mediator production, we examined the involvement MAPK-induced CREB activation in P2RX7 action. Our data reveal that stimulation of multiple monocytic cell lines with P2RX7 agonists induces rapid CREB phosphorylation. In addition, we observed a lack of nucleotide-induced CREB phosphorylation in RAW 264.7 cells expressing nonfunctional P2RX7 and a gain of nucleotide-induced CREB phosphorylation in human embryonic kidney-293 cells that heterologously express human P2RX7. Furthermore, our results indicate that P2RX7 agonist-induced CREB phosphorylation is partly mediated via Ca2+ fluxes and the MEK/ERK system. Mechanistic analyses revealed that macrophage stimulation with a P2RX7 agonist induces CREB/CREB-binding protein complex formation, which is necessary for CREB transcriptional activation. Also, we demonstrate that P2RX7 activation induces a known CREB-dependent gene (c-fos) and that dominant-negative CREB constructs attenuate this response. These studies support the idea that P2RX7 stimulation can directly regulate protein expression that is not dependent on costimulation with other immune modulators such as LPS.