Sato Takeshi, Saito Rumina, Jinushi Takafumi, Tsuji Takemasa, Matsuzaki Junko, Koda Toshiaki, Nishimura Shin ichiro, Takeshima Hidetsugu, Nishimura Takashi
Division of Immunoregulation, Section of Disease Control, Institute for Genetic Medicine, Hokkaido University, Japan.
Biochem Biophys Res Commun. 2004 Feb 6;314(2):468-75. doi: 10.1016/j.bbrc.2003.12.124.
The production of eotaxin, which is a critical mediator for airway inflammation, is inhibited by IFN-gamma. Here, we investigated the precise mechanisms underlying IFN-gamma-dependent inhibition of eotaxin production using mouse embryonic fibroblasts (MEF). MEF produced high levels of eotaxin in STAT6-dependent manner when they were cultured with both IL-4 and TNF-alpha. However, the eotaxin production by MEF was strongly inhibited by addition of IFN-gamma. Western-blotting analysis demonstrated that IFN-gamma downmodulated STAT6 phosphorylation induced by IL-4 and TNF-alpha. Moreover, IFN-gamma did not exhibit its inhibitory effect on both STAT6-phosphorylation and eotaxin production in MEF obtained from deficient mice in STAT1, a key molecule of IFN-gamma signaling. We also demonstrated that SOCS-1, a potent inhibitory molecule of IL-4 signaling, was induced by IFN-gamma in STAT1-dependent manner. This indicated that SOCS-1 might be involved in IFN-gamma-mediated STAT1-dependent inhibition of eotaxin production. In SOCS-1(-/-) MEF, IFN-gamma inhibited neither STAT6 phosphorylation nor eotaxin production induced by IL-4 and TNF-alpha. Conversely, retroviral transduction of SOCS-1 into MEF inhibited STAT6 phosphorylation and eotaxin production induced by IL-4 and TNF-alpha, in the absence of IFN-gamma. Thus, we demonstrated that IFN-gamma-induced inhibition of STAT6 phosphorylation and eotaxin production were mediated by SOCS-1 induced in STAT1-dependent manner.
嗜酸性粒细胞趋化因子是气道炎症的关键介质，其产生受到γ干扰素的抑制。在此，我们利用小鼠胚胎成纤维细胞（MEF）研究了γ干扰素依赖性抑制嗜酸性粒细胞趋化因子产生的精确机制。当MEF与白细胞介素-4（IL-4）和肿瘤坏死因子-α（TNF-α）共同培养时，它们以依赖信号转导及转录激活因子6（STAT6）的方式产生高水平的嗜酸性粒细胞趋化因子。然而，添加γ干扰素可强烈抑制MEF产生嗜酸性粒细胞趋化因子。蛋白质免疫印迹分析表明，γ干扰素可下调由IL-4和TNF-α诱导的STAT6磷酸化。此外，γ干扰素对来自STAT1基因缺陷小鼠的MEF中的STAT6磷酸化和嗜酸性粒细胞趋化因子产生均未表现出抑制作用，STAT1是γ干扰素信号传导的关键分子。我们还证明，IL-4信号的强效抑制分子细胞因子信号转导抑制因子1（SOCS-1）可由γ干扰素以依赖STAT1的方式诱导产生。这表明SOCS-1可能参与了γ干扰素介导的STAT1依赖性抑制嗜酸性粒细胞趋化因子产生的过程。在SOCS-1基因敲除的MEF中，γ干扰素既不抑制由IL-4和TNF-α诱导的STAT6磷酸化，也不抑制嗜酸性粒细胞趋化因子的产生。相反，在没有γ干扰素的情况下，将SOCS-1逆转录病毒转导至MEF可抑制由IL-4和TNF-α诱导的STAT6磷酸化和嗜酸性粒细胞趋化因子产生。因此，我们证明γ干扰素诱导的STAT6磷酸化和嗜酸性粒细胞趋化因子产生的抑制作用是由以依赖STAT1的方式诱导产生的SOCS-1介导的。
