Ligation of CD40 stimulates the induction of nitric-oxide synthase in microglial cells
Ligation of CD40 stimulates the induction of nitric-oxide synthase in microglial cells
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DOI：
10.1074/jbc.m106771200
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发表时间：
2001-11-30
影响因子：
4.8
通讯作者：
Pahan, K
中科院分区：
文献类型：
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作者：
Jana, M;Liu, XJ;Pahan, K
本研究旨在探讨 CD40 连接在小鼠 BV-2 小胶质细胞和原代小胶质细胞中诱导型一氧化氮合酶 (iNOS) 表达中的作用。通过针对 CD40 的交联抗体或重组 CD40 配体 (CD154) 单独连接 CD40 无法诱导 BV-2 小胶质细胞中 NO 的产生。即使在CD40过表达的BV-2小胶质细胞中，仅通过CD40连接也无法诱导NO产生，这表明仅通过CD40连接转导的信号不足以诱导NO产生。然而，CD40 连接显着刺激了干扰素-γ (IFN-γ) 介导的 NO 产生。 CD40过表达细胞中CD40的连接进一步刺激IFN-γ诱导的NO产生。这种NO产生的刺激伴随着iNOS蛋白和mRNA的刺激。除了BV-2神经胶质细胞之外，CD40连接还刺激小鼠原代小胶质细胞和腹膜巨噬细胞中IFN-γ介导的NO产生。为了了解诱导/刺激 iNOS 的机制，我们研究了负责诱导 iNOS 的转录因子核因子 kappaB (NF-kappaB) 和 CCAAT/增强子结合蛋白 β (C/EBP β) 的作用。单独的 IFN-gamma 能够诱导 NF-kappaB 以及 C/EBP beta 的激活。然而，单独的CD40连接仅诱导NF-kappaB的激活，而不诱导C/EBPβ的激活，这表明仅通过CD40连接激活NF-kappaB不足以诱导iNOS的表达，并且C/EBPβ的激活对于iNOS的表达也是必需的。一致地，p65 (Delta p65) 和 C/EBP beta (DeltaC/EBP beta) 的显性失活突变体抑制了用 IFN-γ 和 CD40 配体组合刺激的 BV-2 小胶质细胞中 iNOS 的表达。 CD40 连接刺激 IFN-γ 介导的 NF-κB 激活，但不刺激 C/EBP β 激活，表明 CD40 连接通过刺激 NF-κB 激活，刺激 IFN-γ 处理的 BV-2 小胶质细胞中 iNOS 的表达。这项研究说明了 CD40 连接在刺激小胶质细胞中 iNOS 表达方面的新作用，这可能参与神经炎症疾病的发病机制。
The present study was undertaken to investigate the role of CD40 ligation in the expression of inducible nitric-oxide synthase (iNOS) in mouse BV-2 microglial cells and primary microglia. Ligation of CD40 alone by either cross-linking antibodies against CD40 or a recombinant CD40 ligand (CD154) was unable to induce the production of NO in BV-2 microglial cells. The absence of induction of NO production by CD40 ligation alone even in CD40-overexpressed BV-2 microglial cells suggests that a signal transduced by the ligation of CD40 alone is not sufficient to induce NO production. However, CD40 ligation markedly stimulated interferon-gamma (IFN-gamma)-mediated NO production. Ligation of CD40 in CD40-overexpressed cells further stimulated IFN-gamma -induced production of NO. This stimulation of NO production was accompanied by stimulation of the iNOS protein and mRNA In addition to BV-2 glial cells, CD40 ligation also stimulated IFN-gamma -mediated NO production in mouse primary microglia and peritoneal macrophages. To understand the mechanism of induction/stimulation of iNOS, we investigated the roles of nuclear factor kappaB (NF-kappaB) and CCAAT/enhancer-binding protein beta (C/EBP beta), transcription factors responsible for the induction of iNOS. IFN-gamma alone was able to induce the activation of NF-kappaB as well as C/EBP beta. However, CD40 ligation alone induced the activation of only NF-kappaB but not of C/EBP beta, suggesting that the activation of NF-kappaB alone by CD40 ligation is not sufficient to induce the expression of iNOS and that the activation of C/EBP beta is also necessary for the expression of iNOS. Consistently, dominant-negative mutants of p65 (Delta p65) and C/EBP beta (DeltaC/EBP beta) inhibited the expression of iNOS in BV-2 microglial cells that were stimulated with the combination of IFN-gamma and CD40 ligand. Stimulation of IFN-gamma -mediated activation of NF-kappaB but not of C/EBP beta by CD40 ligation suggests that CD40 ligation stimulates the expression of iNOS in IFN-gamma -treated BV-2 microglial cells through the stimulation of NF-kappaB activation. This study illustrates a novel role for CD40 ligation in stimulating the expression of iNOS in microglial cells, which may participate in the pathogenesis of neuroinflammatory diseases.