Inhibition of tumor necrosis factor-α transcription in macrophages exposed to febrile range temperature -: A possible role for heat shock factor-1 as a negative transcriptional regulator
Inhibition of tumor necrosis factor-α transcription in macrophages exposed to febrile range temperature -: A possible role for heat shock factor-1 as a negative transcriptional regulator
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DOI：
10.1074/jbc.275.13.9841
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发表时间：
2000-03-31
影响因子：
4.8
通讯作者：
Hasday, JD
中科院分区：
文献类型：
--
作者：
Singh, IS;Viscardi, RM;Hasday, JD
我们以前曾报道，暴露在高温范围内的巨噬细胞中肿瘤坏死因子-α(TNF-α)的表达减弱。在这项研究中，我们分析了温度对RAW 264.7巨噬细胞系在37℃和39.5℃孵育过程中肿瘤坏死因子α转录的影响。在37℃和39.5℃培养的细胞中，内毒素刺激后肿瘤坏死因子α转录的初始激活程度相似，在内毒素刺激10min内达到峰值。然而，与37℃细胞(2-4h)相比，39.5℃细胞的转录激活持续时间(30-60min)显著缩短。对肿瘤坏死因子α基因的缺失图谱显示，其近端85个核苷酸的启动子序列和5‘-非翻译区足以满足温度敏感性。该序列含有热休克反应元件(HRE)的6个半位点，但没有完整的HREs，凝胶迁移率漂移和免疫印迹分析表明，在没有热休克蛋白-70基因激活的情况下，39.5℃的C细胞发生了热休克因子(HSF)的核易位并激活为DNA结合形式。近端的肿瘤坏死因子α启动子/5‘-非翻译区序列竞争HSF与经典的HRE结合。HSF-1的过表达降低了肿瘤坏死因子α启动子的活性。这些数据表明，在高温、亚热休克温度下，HSF-I的部分激活可能通过与其近端启动子或5‘-非翻译区结合来阻止肿瘤坏死因子α的转录。
We previously reported that expression of tumor necrosis factor-alpha (TNF alpha) was attenuated in macrophages exposed to febrile range temperatures. In this study, we analyzed the influence of temperature on TNF alpha transcription in the Raw 264.7 macrophage cell line during incubation at 37 and 39.5 degrees C, The initial activation of TNF alpha transcription in response to endotoxin (LPS) was comparable in the 37 and 39.5 degrees C cell cultures, peaking within 10 min of LPS stimulation. However, the duration of transcriptional activation was markedly reduced in the 39.5 degrees C cells (30-60 min) compared with the 37 degrees C cells (2-4 h), Deletion mapping of the TNF alpha gene revealed that the proximal 85-nucleotide promoter sequence and the 5'-untranslated region were sufficient for temperature sensitivity. This sequence contains six heat shock response element (HRE) half-sites but no complete HREs, Electrophoretic mobility shift and immunoblot assays demonstrated that nuclear transclocation of heat shock factor (HSF) and its activation to a DNA-binding form occurred in the 39.5 degrees C cells in the absence of heat shock protein-70 gene activation. The proximal TNF alpha promoter/5'-untranslated region sequence competed for HSF binding to a classic HRE. Overexpression of HSF-1 reduced activity of the TNF alpha promoter. These data suggest that partial activation of HSF-I during exposure to febrile, sub-heat shock temperatures may block TNF alpha transcription by binding to its proximal promoter or 5'-untranslated region.