Silencing carboxylesterase 1 in human THP-1 macrophages perturbs genes regulated by PPARγ/RXR and RAR/RXR: down-regulation of CYP27A1-LXRα signaling.
Silencing carboxylesterase 1 in human THP-1 macrophages perturbs genes regulated by PPARγ/RXR and RAR/RXR: down-regulation of CYP27A1-LXRα signaling.
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DOI：
10.1042/bcj20180008
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发表时间：
2018-02-09
期刊：
影响因子：
--
通讯作者：
Crow JA
中科院分区：
文献类型：
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作者：
Mangum LC;Hou X;Borazjani A;Lee JH;Ross MK;Crow JA
巨噬细胞泡沫细胞将过量的胆固醇储存为胆固醇酯，胆固醇酯需要水解以使胆固醇流出。我们最近报道，在人类THP-1巨噬细胞（CES 1 KD巨噬细胞）中沉默羧酸酯酶1（CES 1）的表达降低了胆固醇摄取，并降低了载有乙酰化低密度脂蛋白（acLDL）的细胞中CD 36和清道夫受体-A的表达。在这里，我们报告，CES 1 KD巨噬细胞表现出细胞色素P450 27 A1（CYP 27 A1）在非负载和acLDL负载细胞的转录减少。此外，CYP 27 A1蛋白及其酶产物27-羟基胆固醇的水平在CES 1 KD巨噬细胞中显著降低。在acLDL负载的CES 1 KD巨噬细胞中，LXRα和ABCA 1的转录也降低，表明通过PPARγ-CYP 27 A1-LXRα的信号传导减少。与此一致，用PPARγ、RAR和/或RAR/RXR激动剂处理CES 1 KD巨噬细胞部分恢复了CYP 27 A1和LXRα的转录，并修复了胆固醇内流。相反，用PPARγ和/或RXR拮抗剂处理对照巨噬细胞可降低CYP 27 A1和LXRα的转录。在野生型THP-1细胞和原代人巨噬细胞中对CES 1的药理学抑制也降低了CYP 27 A1转录。CES 1沉默不影响acLDL负载的巨噬细胞中的PPARγ和RXR的转录水平，而它确实降低了内源性大麻素2-花生四烯酸甘油的催化活性。最后，在acLDL暴露后，CES 1 KD巨噬细胞的基因表达谱与PPARγ敲低细胞的基因表达谱相似，进一步表明CES 1和PPARγ之间存在机制联系。这些结果与模型一致，其中CES 1功能的消除通过消耗调节胆固醇稳态的核受体PPARγ、RAR和/或RXR的内源性配体来减弱CYP 27 A1-LXRα-ABCA 1信号传导轴。
Macrophage foam cells store excess cholesterol as cholesteryl esters, which need to be hydrolyzed for cholesterol efflux. We recently reported that silencing expression of carboxylesterase 1 (CES1) in human THP-1 macrophages (CES1KD macrophages) reduced cholesterol uptake and decreased expression of CD36 and scavenger receptor-A in cells loaded with acetylated low-density lipoprotein (acLDL). Here, we report that CES1KD macrophages exhibit reduced transcription of cytochrome P450 27A1 (CYP27A1) in non-loaded and acLDL-loaded cells. Moreover, levels of CYP27A1 protein and its enzymatic product, 27-hydroxycholesterol, were markedly reduced in CES1KD macrophages. Transcription of LXRα and ABCA1 was also decreased in acLDL-loaded CES1KD macrophages, suggesting reduced signaling through PPARγ-CYP27A1-LXRα. Consistent with this, treatment of CES1KD macrophages with agonists for PPARγ, RAR, and/or RAR/RXR partially restored transcription of CYP27A1 and LXRα, and repaired cholesterol influx. Conversely, treatment of control macrophages with antagonists for PPARγ and/or RXR decreased transcription of CYP27A1 and LXRα. Pharmacologic inhibition of CES1 in both wildtype THP-1 cells and primary human macrophages also decreased CYP27A1 transcription. CES1 silencing did not affect transcript levels of PPARγ and RXR in acLDL-loaded macrophages, whereas it did reduce the catabolism of the endocannabinoid 2-arachidonoylglycerol. Finally, the gene expression profile of CES1KD macrophages was similar to that of PPARγ knockdown cells following acLDL exposures, further suggesting a mechanistic link between CES1 and PPARγ. These results are consistent with a model in which abrogation of CES1 function attenuates the CYP27A1-LXRα-ABCA1 signaling axis by depleting endogenous ligands for the nuclear receptors PPARγ, RAR, and/or RXR that regulate cholesterol homeostasis.