Involvement of MAPK activation in bacterial endotoxin-inducible tissue factor upregulation in human monocytic THP-1 cells
Involvement of MAPK activation in bacterial endotoxin-inducible tissue factor upregulation in human monocytic THP-1 cells
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DOI：
10.1006/jsre.2001.6271
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发表时间：
2001-11-01
影响因子：
2.2
通讯作者：
Seto, A
中科院分区：
文献类型：
--
作者：
Chu, AJ;Wang, ZG;Seto, A
背景资料。单核细胞组织因子(MTF)高凝导致败血症后血栓并发症是常见的并发症。在此，我们研究了细菌内毒素(脂多糖；大肠杆菌O111：B04)上调人单核细胞THP-1细胞MTF的细胞内机制，确定丝裂原活化蛋白激酶(MAPK)是否参与了这一信号转导。我们分别通过细胞表面表达、蛋白质合成和基于流式细胞术、Western blotting分析和单期凝血试验的功能活性来评估MTF的上调。内毒素(100 ng/ml)作用3h后，细胞表面MTF表达和合成增加，MTF功能活性增强。金雀异黄素(G)抑制脂多糖诱导的MTF上调，提示蛋白酪氨酸激酶参与了MTF的上调。脂多糖激活MAPK，G、SB 203580(SB)和PD 98058(PD)对其有明显的抑制作用。有趣的是，Sb和Pd的加入也显著减少了内毒素诱导的MTF上调。MAPK和MTF活性之间的平行关系表明MAPK的激活参与了MTF的上调。根据SB和PD分别阻断脂多糖诱导的p38MAPK和ERK1/2酪氨酸磷酸化的能力，很明显MAPKs的酪氨酸磷酸化是介导脂多糖诱导的MTF合成和上调所必需的。与这些抑制剂已建立的阻止MTF上调的方法相比，未能抵消已经被内毒素诱导的MTF活性，似乎与内毒素容易激活负责MTF合成的MAPK的观点是一致的。我们的数据表明，MAPKs(p38和ERK1/2)的酪氨酸磷酸化导致它们的激活可能是内毒素诱导MTF合成的先决条件，有助于上调MTF启动的外源性凝血。(C)2001年学术出版社。
Background. Monocytic tissue factor (mTF) hypercoagulation leading to thrombotic complications is commonly observed following sepsis.Objective. We herein study the intracellular mechanism of mTF upregulation in human model monocytic THP-1 cells in response to bacterial endotoxin (lipopolysaccharide, LPS; Escherichia coli O111:B04), determining if mitogen-activated protein kinase (MAPK) activation is involved in the signaling.Methods. We assessed mTF upregulation by its cell surface expression, protein synthesis, and functional activity based on flow cytometry, Western blotting analysis, and a single-stage clotting assay, respectively.Results. A 3-h challenge with LPS (100 ng/ml) drastically induced mTF functional activity, accompanied by elevated surface mTF expression and synthesis. The suppression by genistein (G) of LPS-inducible mTF upregulation implied the involvement of protein tyrosine kinase activation in mTF upregulation. LPS activated MAPK, which was significantly depressed by G, SB 203580 (SB), and PD 98058 (PD). Interestingly, inclusion of SB and PD also markedly diminished LPS-inducible mTF upregulation. The parallelism between MAPK and mTF activities revealed the involvement of MAPK activation in such mTF upregulation. Based on the ability of SB and PD to respectively block LPS-inducible tyrosine phosphorylation of p38 MAPK and Erk1/2, it was evident that tyrosine phosphorylation of MAPKs is required for mediating LPS-inducible mTF synthesis and upregulation. Contrasting with the established prevention of mTF upregulation by these inhibitors, failure to offset the already LPS-induced mTF activity seemed to be consistent with the view that LPS readily activated MAPK responsible for mTF synthesis.Conclusion. Our data suggest that the tyrosine phosphorylation of MAPKs (p38 and Erk1/2) leading to their activation could be a prerequisite for LPS induction of mTF synthesis contributing to the upregulation of mTF-initiated extrinsic coagulation. (C) 2001 Academic Press.