Shin Hyun-Hee, Lee Hyeon Woo, Choi Hye-Seon
Department of Biological Sciences, Immunomodulation Research Center, University of Ulsan, Ulsan 680-749, Korea.
Exp Mol Med. 2003 Jun 30;35(3):175-80. doi: 10.1038/emm.2003.24.
Earlier study showed that glucocorticoid induced tumor necrosis factor receptor (GITR), a new TNFR family, activated murine macrophages to express inducible nitric oxide synthase (iNOS) and to generate nitric oxide (NO). A possible involvement of pro-inflammatory cytokines on NO production by GITR was investigated in vitro systems and signaling molecules contributing to sGITR-induced iNOS production are determined in Raw 264.7 cells, a murine macrophage cell line. The result showed that the synergy was afforded by the combination of GITR with IFN-g in a dose-dependent manner but IFN-gamma alone was not able to induce NOS. No effects were observed with TNF-alpha, IL-1beta, or IL-6 co-treated with GITR. To determine signaling molecules contributing to sGITR-induced iNOS production, a specific inhibitor for signal pathway proteins tested showed that PDTC (NF-kappaB) and genistein (tyrosine kinase) inhibited NOS induction significantly, while sodium orthovanadate (tyrosine phosphatase) potentiated NOS expression. These results suggest that activations of NF-kappaB were involved in induction of iNOS by GITR and IFN-gamma priming caused earlier and stronger NF-kappaB activation.
早期研究表明，糖皮质激素诱导的肿瘤坏死因子受体（GITR）是肿瘤坏死因子受体（TNFR）家族的新成员，它可激活小鼠巨噬细胞，使其表达诱导型一氧化氮合酶（iNOS）并产生一氧化氮（NO）。在体外系统中研究了促炎细胞因子对GITR介导的NO产生的可能影响，并在小鼠巨噬细胞系Raw 264.7细胞中确定了有助于可溶性GITR（sGITR）诱导iNOS产生的信号分子。结果表明，GITR与干扰素-γ（IFN-γ）联合可产生剂量依赖性协同作用，但单独的IFN-γ不能诱导一氧化氮合酶（NOS）。GITR与肿瘤坏死因子-α（TNF-α）、白细胞介素-1β（IL-1β）或白细胞介素-6（IL-6）共同处理未观察到效果。为了确定有助于sGITR诱导iNOS产生的信号分子，对信号通路蛋白的特异性抑制剂进行测试，结果显示，吡咯烷二硫代氨基甲酸盐（PDTC，NF-κB抑制剂）和染料木黄酮（酪氨酸激酶抑制剂）可显著抑制NOS诱导，而原钒酸钠（酪氨酸磷酸酶抑制剂）可增强NOS表达。这些结果表明，NF-κB的激活参与了GITR诱导的iNOS生成，且IFN-γ预处理可导致更早、更强的NF-κB激活。
