Vomitoxin-induced cyclooxygenase-2 gene expression in macrophages mediated by activation of ERK and p38 but not JNK mitogen-activated protein kinases
Vomitoxin-induced cyclooxygenase-2 gene expression in macrophages mediated by activation of ERK and p38 but not JNK mitogen-activated protein kinases
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DOI：
10.1093/toxsci/69.2.373
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发表时间：
2002-10-01
影响因子：
3.8
通讯作者：
Pestka, JJ
中科院分区：
文献类型：
--
作者：
Moon, Y;Pestka, JJ
呕吐毒素（VT）和其他倍半萜类真菌毒素通过诱导白细胞中的炎症相关基因介导广泛的免疫毒性作用。本研究的目的是检验VT诱导巨噬细胞中环氧合酶-2（考克斯-2）基因表达的假设，以及这是在丝裂原活化蛋白激酶（MAPK）水平上调节的假设。将小鼠巨噬细胞系RAW 264.7暴露于50-250 ng/ml VT 24 h，显著增强前列腺素E-2（PGE（2））的产生，PGE（2）是考克斯-2的主要代谢物。在VT处理的细胞中，PGE（2）升高之前，考克斯-2 mRNA（2 h）和考克斯-2蛋白（15 h）增加。VT诱导细胞外信号调节蛋白激酶1和2（ERK 1/2）和p38 MAPK的快速（15 min）和持续（长达240 min）磷酸化，以及c-Jun N-末端激酶1和2（JNK 1/2）的快速（15 min）但短暂（长达60 min）磷酸化。ERK抑制剂PD 98059和p38抑制剂SB 203580抑制VT诱导的PGE（2）和考克斯-2蛋白表达，而通过瞬时转染显性负性（dn）JNK载体来损害JNK功能对考克斯-2蛋白表达没有影响。相关地，在用考克斯-2启动子-荧光素酶构建体转染的细胞中，PD 98059-和SB 203580-处理，而不是dnJNK-处理，抑制VT诱导的荧光素酶转录。VT也增加了考克斯-2 mRNA的稳定性，这是由PD 98059抑制，但不被SB 203580。综上所述，这些结果表明，VT诱导PGE（2）的生产和考克斯-2的表达，通过提高转录活性和mRNA的稳定性。增强的转录活性通过ERK和p38信号通路调节，而mRNA稳定性仅通过VT激活的p38磷酸化促进。这些数据提供了深入了解VT和其他trichlothecenes上调促炎基因和赋予免疫毒性的可能的一般机制。
Vomitoxin (VT) and other trichothecene mycotoxins mediate a broad range of immunotoxic effects via the induction of inflammation-associated genes in leukocytes. The purpose of this study was to test the hypothesis that VT induces cyclooxygenase-2 (COX-2) gene expression in macrophages and that this is regulated at the level of mitogen-activated protein kinases (MAPKs). Exposure of the murine macrophage cell line RAW 264.7 to 50-250 ng/ml VT for 24 h markedly enhanced the production of prostaglandin E-2 (PGE(2)), a major COX-2 metabolite. PGE(2) elevation was preceded by increases in COX-2 mRNA (2 h) and COX-2 protein (15 h) in VT-treated cells. VT induced rapid (15 min) and persistent (up to 240 min) phosphorylation of extracellular, signal regulated protein kinases 1 and 2 (ERK1/2) and p38 MAPK as well as a rapid (15 min) but transient (up to 60 min) phosphorylation of c-Jun N-terminal kinases 1 and 2 (JNK1/2). The ERK inhibitor PD98059 and p38 inhibitor SB203580 suppressed VT-induced PGE(2) and COX-2 protein expression, whereas impairment of JNK function by transient transfection with a dominant negative (dn) JNK vector had no effect on COX-2 protein expression. Relatedly, in cells transfected with a COX-2 promoter-luciferase construct, PD98059- and SB203580-, but not dnJNK-treatment, suppressed VT-induced luciferase transcription. VT also increased COX-2 mRNA stability, and this was inhibited by PD98059 but not by SB203580. Taken together, these results indicate that VT-induced PGE(2) production and COX-2 expression by elevating transcriptional activity and mRNA stability. Enhanced transcriptional activity was modulated by ERK and p38 signaling pathways, whereas mRNA stability was promoted exclusively by VT-activated p38 phosphorylation. These data provide insight into possible general mechanisms by which VT and other trichlothecenes upregulate proinflammatory genes and impart immunotoxicity.