Evidence for nucleotide receptor modulation of cross talk between MAP kinase and NF-κB signaling pathways in murine RAW 264.7 macrophages
Evidence for nucleotide receptor modulation of cross talk between MAP kinase and NF-κB signaling pathways in murine RAW 264.7 macrophages
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DOI：
10.1152/ajpcell.00417.2003
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发表时间：
2004-04-01
影响因子：
5.5
通讯作者：
Bertics, PJ
中科院分区：
文献类型：
--
作者：
Aga, M;Watters, JJ;Bertics, PJ
细胞外核苷酸如ATP在炎症和组织损伤部位大量存在，这些物质通过核苷酸受体P2X对巨噬细胞/单核细胞功能发挥强大的调节作用(7)。在这方面，暴露于细菌LPS后，P2X(7)激活增加了巨噬细胞中诱导型一氧化氮（NO）合成酶的表达和NO的产生。由于P2X(7)已被报道能刺激MAP激酶家族的某些成员（ERK1/2），并能增强NF-kappaB的dna结合活性，我们验证了LPS和核苷酸通过与mapk相关通路的串扰调节NF-kappaB依赖性炎症事件的假设。在这方面，目前的研究表明，LPS和P2X(7)选择性配体2'-3'- o -（4-苯甲酰苯甲酰）腺苷5'-三磷酸（BzATP）共同处理巨噬细胞导致NF-kappaB dna结合活性的协同激活和NF-kappaB抑制蛋白IkappaBalpha水平的持续衰减。有趣的是，当MEK1/2抑制剂U0126与LPS共给药时，也观察到IkappaBalpha水平的持续降低，这表明MEK/ERK途径的成分参与调节IkappaBalpha蛋白的表达和/或周转。U0126和BzATP在LPS诱导的IkappaBalpha水平变化中表现出重叠的作用，这一发现得到了支持。研究发现，与单独处理BzATP相比，巨噬细胞与BzATP和LPS共处理后，MEK/ERK激活上游的Ras激活减少。这些数据与Ras/MEK/ERK通路参与调节NF-kappaB/ ikappab依赖性炎症介质产生的概念一致，并提示了一种以前未被发现的机制，即核苷酸可以通过NF-kappaB和Ras/MEK/ mapk相关通路之间的串扰来调节lps诱导的作用。
Extracellular nucleotides such as ATP are present in abundance at sites of inflammation and tissue damage, and these agents exert a potent modulatory effect on macrophage/monocyte function via the nucleotide receptor P2X(7). In this regard, after exposure to bacterial LPS, P2X(7) activation augments expression of the inducible nitric oxide ( NO) synthase and production of NO in macrophages. Because P2X(7) has been reported to stimulate certain members of the MAP kinase family (ERK1/2) and can enhance the DNA-binding activity of NF-kappaB, we tested the hypothesis that LPS and nucleotides regulate NF-kappaB-dependent inflammatory events via cross talk with MAPK-associated pathways. In this regard, the present studies revealed that cotreatment of macrophages with LPS and the P2X(7)-selective ligand 2'-3'-O-(4-benzoylbenzoyl)adenosine 5'-triphosphate (BzATP) results in the cooperative activation of NF-kappaB DNA-binding activity and a sustained attenuation of levels of the NF-kappaB inhibitory protein IkappaBalpha. Interestingly, a persistent reduction in IkappaBalpha levels is also observed when the MEK1/2 inhibitor U0126 is coadministered with LPS, suggesting that components of the MEK/ERK pathway are involved in regulating IkappaBalpha protein expression and/or turnover. The observation that U0126 and BzATP exhibit overlapping actions with respect to LPS-induced changes in IkappaBalpha levels is supported by the finding that Ras activation, which is upstream of MEK/ERK activation, is reduced upon macrophage cotreatment with BzATP and LPS compared with the effects of BzATP treatment alone. These data are consistent with the concept that the Ras/MEK/ERK pathways are involved in regulating NF-kappaB/IkappaB-dependent inflammatory mediator production and suggest a previously unidentified mechanism by which nucleotides can modulate LPS-induced action via cross talk between NF-kappaB and Ras/MEK/MAPK-associated pathways.