Inhibition of carboxylesterase activity of THP1 monocytes/macrophages and recombinant human carboxylesterase 1 by oxysterols and fatty acids.
Inhibition of carboxylesterase activity of THP1 monocytes/macrophages and recombinant human carboxylesterase 1 by oxysterols and fatty acids.
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DOI：
10.1016/j.bbalip.2009.09.002
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发表时间：
2010-01
期刊：
影响因子：
--
通讯作者：
Ross MK
中科院分区：
文献类型：
--
作者：
Crow JA;Herring KL;Xie S;Borazjani A;Potter PM;Ross MK
人类羧酸酯酶(CES)的两种主要亚型在代谢活跃的组织中被发现，即CES1和CES2。这些水解酶参与了异生和内生代谢。CES1在人肝脏和单核/巨噬细胞，包括THP1细胞中大量表达；CES2在肝脏中表达，但在单核/巨噬细胞中不表达。人巨噬细胞中胆固醇酯的水解活性归因于CES1。在这里，我们报道了几种内源性氧化甾醇和脂肪酸对THP1单核/巨噬细胞以及重组人CES1和CES2的CE活性的直接抑制作用。结果表明：(1)27-羟基胆固醇(27-HC)对羧酸酯酶活性有较强的抑制作用(IC_(50)=33μ)；(2)24(S)，25-环氧胆碱具有中等抑制活性(IC_(50)=8.1nM)；(3)胆固醇、7-酮胆固醇、22(R)-羟基胆固醇、24(S)-羟基胆固醇和25-羟基胆固醇均无抑制活性。27-HC是重组CES1(KiAPP=10 nM)的部分非竞争性抑制剂，在处理完整的THP1细胞后，细胞内CES1的活性受到损害。相反，27-HC不抑制重组CES2的活性，提示27-HC对重组CES2有选择性抑制作用。此外，不饱和脂肪酸对CES1活性的抑制作用强于饱和脂肪酸，而CES2活性不受任何脂肪酸的影响。花生四烯酸(AA)是重组CES1最有效的脂肪酸抑制物，其作用机制为非竞争性(KiAPP=1.7μM)，当不与白蛋白络合时，外源性AA可穿透完整的THP1细胞并抑制CES1。根据CES1最近的结构模型讨论了抑制结果，这些模型描述了与活性部位分开的配体结合部位。此外，外源27-HC对人肝匀浆或完整的THP1细胞的CES1活性有明显的抑制作用，从而显著减少了拟除虫菊酯杀虫剂生物氯氰菊酯(CES1特异性异源底物)的降解。总之，这些发现表明，重组CES1、细胞裂解物和完整细胞的CE活性可以受到自然产生的脂类的损害，这可能会损害CES1对环境污染物的解毒和体内内源化合物的代谢能力。
Two major isoforms of human carboxylesterases (CEs) are found in metabolically active tissues, CES1 and CES2. These hydrolytic enzymes are involved in xenobiotic and endobiotic metabolism. CES1 is abundantly expressed in human liver and monocytes/macrophages, including the THP1 cell line; CES2 is expressed in liver but not in monocytes/macrophages. The cholesteryl ester hydrolysis activity in human macrophages has been attributed to CES1. Here, we report the direct inhibitory effects of several endogenous oxysterols and fatty acids on the CE activity of THP1 monocytes/macrophages and recombinant human CES1 and CES2. Using THP1 whole-cell lysates we found: (1) 27-hydroxycholesterol (27-HC) is a potent inhibitor of carboxylesterase activity (IC50=33 nM); (2) 24(S),25-epoxycholesterol had moderate inhibitory activity (IC50=8.1 μM); and (3) cholesterol, 7-ketocholesterol, 22(R)-hydroxycholesterol, 24(S)-hydroxycholesterol, and 25-hydroxycholesterol each had little inhibitory activity. 27-HC was a partially noncompetitive inhibitor of recombinant CES1 (Kiapp=10 nM) and impaired intracellular CES1 activity following treatment of intact THP1 cells. In contrast, recombinant CES2 activity was not inhibited by 27-HC, suggesting isoform-selective inhibition by 27-HC. Furthermore, unsaturated fatty acids were better inhibitors of CES1 activity than saturated fatty acids, while CES2 activity was unaffected by any fatty acid. Arachidonic acid (AA) was the most potent fatty acid inhibitor of recombinant CES1 and acted by a noncompetitive mechanism (Kiapp=1.7 μM); when not complexed to albumin, exogenous AA penetrated intact THP1 cells and inhibited CES1. Inhibition results are discussed in light of recent structural models for CES1 that describe ligand binding sites separate from the active site. In addition, oxysterol-mediated inhibition of CES1 activity was demonstrated by pretreatment of human liver homogenates or intact THP1 cells with exogenous 27-HC, which resulted in significantly reduced hydrolysis of the pyrethroid insecticide bioresmethrin, a CES1-specific xenobiotic substrate. Collectively, these findings suggest that CE activity of recombinant CES1, cell lysates, and intact cells can be impaired by naturally occurring lipids, which may compromise the ability of CES1 to both detoxify environmental pollutants and metabolize endogenous compounds in vivo.
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影响因子：
7.7
作者：
Okazaki, Hiroaki;Igarashi, Masaki;Ishibashi, Shun
通讯作者：
Ishibashi, Shun
影响因子：
5.6
作者：
Bencharit, Sompop;Edwards, Carol C.;Redinbo, Matthew R.
通讯作者：
Redinbo, Matthew R.
DOI：
10.1006/bbrc.2001.5078
发表时间：
2001-06-22
影响因子：
3.1
作者：
Ghosh, S;Natarajan, R
通讯作者：
Natarajan, R
影响因子：
6.5
作者：
Honda, Akira;Yamashita, Kouwa;Matsuzaki, Yasushi
通讯作者：
Matsuzaki, Yasushi
DOI：
10.1161/atvbaha.107.157115
发表时间：
2008-06-01
影响因子：
8.7
作者：
Ouimet, Mireille;Wang, Ming-Dong;Marcel, Yves L.
通讯作者：
Marcel, Yves L.