IFN-γ-Induced TNF-α Expression Is Regulated by Interferon Regulatory Factors 1 and 8 in Mouse Macrophages1
IFN-γ-Induced TNF-α Expression Is Regulated by Interferon Regulatory Factors 1 and 8 in Mouse Macrophages1
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小鼠巨噬细胞中 IFN-γ 诱导的 TNF-α 表达受干扰素调节因子 1 和 8 调节1
作者：
Virginia Vila‐del Sol;C. Punzón;M. Fresno
我们先前已经描述了IFN-γ通过内源性产生TNF-α的机制诱导环氧合酶2和诱导型NO合酶的表达。在这项研究中，我们报告了IFN-γ处理诱导小鼠巨噬细胞系RAW 264.7产生TNF-α。在用IFN-γ处理的细胞中，TNF-α mRNA水平以时间依赖性方式增加，并且IFN-γ还增加人TNF-α启动子依赖性转录。TNF-α启动子中的两个区域似乎负责IFN-γ应答：位于人TNF-α启动子的-1311和-615 bp之间的远端区域，以及位于转录起始点上游-95和-36 bp之间的近端区域。相反，IFN-γ刺激诱导转录因子IRF-1和IRF-8的表达。这些转录因子的过表达导致人TNF-α启动子的转录活性增加。负责IRF-1和IRF-8引发的转录激活的TNF-α启动子区域与IFN-γ应答所需的区域之间存在相关性。此外，如染色质免疫沉淀试验所示，在IFN-γ处理的RAW 264.7细胞中，IRF-1和IRF-8被募集至TNF-α启动子。此外，IRF-1和IRF-8过表达诱导未刺激RAW 264.7巨噬细胞产生TNF-α，与IFN-γ刺激引起的TNF-α产生相当，使用特异性小干扰RNA沉默IRF-1和/或IRF-8可降低IFN-γ引起的TNF-α产生。总之，IFN-γ处理在转录水平诱导TNF-α表达，需要IRF-1和IRF-8的协调作用。
We have previously described that IFN-γ induces cyclooxygenase 2 and inducible NO synthase expression by a mechanism that involved endogenously produced TNF-α. In this study, we report that TNF-α production is induced by IFN-γ treatment in the murine macrophage cell line RAW 264.7. TNF-α mRNA levels are increased in cells treated with IFN-γ in a time-dependent manner and IFN-γ also increased human TNF-α promoter-dependent transcription. Two regions in the TNF-α promoter seem to be responsible for the IFN-γ response: a distal region between −1311 and −615 bp of the human TNF-α promoter, and a proximal region located between −95 and −36 bp upstream of the transcriptional start. In contrast, IFN-γ stimulation induces the expression of the transcription factors IRF-1 and IRF-8. Overexpression of these transcription factors produces an increase in the transcriptional activity of the human TNF-α promoter. There is a correlation between the regions of the TNF-α promoter responsible of the transcriptional activation elicited by IRF-1 and IRF-8 and those required for IFN-γ response. In addition, IRF-1 and IRF-8 are recruited to the TNF-α promoter in IFN-γ-treated RAW 264.7 cells, as demonstrated by chromatin immunoprecipitation assays. Moreover, overexpression of IRF-1 and IRF-8 induces TNF-α production in unstimulated RAW 264.7 macrophages, comparable to the production of TNF-α elicited by IFN-γ stimulation, and silencing of IRF-1 and/or IRF-8 with specific small interfering RNAs, decreases IFN-γ-elicited TNF-α production. In summary, IFN-γ treatment induces TNF-α expression at transcriptional level requiring the coordinate action of IRF-1 and IRF-8.
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影响因子：
20.3
作者：
Tamura, T;Thotakura, P;Ozato, K
通讯作者：
Ozato, K
影响因子：
4.4
作者：
E. Chan;B. Winston;S. Uh;M. Wynes;D. M. Rose;D. Riches
通讯作者：
E. Chan;B. Winston;S. Uh;M. Wynes;D. M. Rose;D. Riches
影响因子：
5.6
作者：
Saura, M;Zaragoza, C;Lowenstein, CJ
通讯作者：
Lowenstein, CJ
影响因子：
4.4
作者：
C. Salkowski;K. Kopydlowski;J. Blanco;M. J. Cody;R. McNally;S. Vogel
通讯作者：
C. Salkowski;K. Kopydlowski;J. Blanco;M. J. Cody;R. McNally;S. Vogel
影响因子：
2.7
作者：
S. Nordeen
通讯作者：
S. Nordeen