Downregulation of GATA6 in mTOR-inhibited human aortic endothelial cells: effects on TNF-α-induced VCAM-1 expression and monocytic cell adhesion
Downregulation of GATA6 in mTOR-inhibited human aortic endothelial cells: effects on TNF-α-induced VCAM-1 expression and monocytic cell adhesion
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mTOR 抑制的人主动脉内皮细胞中 GATA6 的下调：对 TNF-α 诱导的 VCAM-1 表达和单核细胞粘附的影响
DOI：
10.1152/ajpheart.00411.2018
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发表时间：
2019-02-01
影响因子：
4.8
通讯作者：
Sun, ChongXiu
中科院分区：
文献类型：
--
作者：
Fan, Xing;Chen, Xiaolin;Sun, ChongXiu
血管细胞粘附分子1（VCAM-1）在主动脉内皮上的表达增加是动脉粥样硬化形成的早期标志物，部分由炎症细胞因子（如TNF-α）水平升高促进。哺乳动物雷帕霉素靶蛋白（mTOR）是一种普遍存在的信号分子，通过mTOR复合物1（mTORC 1）或mTORC 2（mTORC 2）参与多种细胞过程。本研究旨在阐明mTOR信号在TNF-α诱导的动脉内皮VCAM-1表达中的作用。原代人主动脉内皮细胞（HAEC）用低剂量（0.1 ng/ml）TNF-α处理，并通过实时定量PCR、Western印迹分析和流式细胞术测量VCAM-1表达。通过siRNA介导的消耗或用化学抑制剂雷帕霉素或torin 1处理来抑制mTOR抑制VCAM 1转录，这转化为HAEC抑制VCAM-1表面表达并伴随单核细胞粘附减少。启动子荧光素酶测定和染色质免疫沉淀表明，mTOR通过涉及转录因子GATA 6的机制调节VCAM 1转录。由mTOR抑制而不是mTORC 1或mTORC 2单独或一起破坏引起的PKC-α激活和milt-200 a-3 p表达增加，降低了TNF诱导的GATA 6表达及其在VCAM 1启动子处的富集。总之，mTOR抑制独立于mTORC 1和/或mTORC 2的破坏而激活PKC-α，这挑战了关于mTOR信号传导的传统智慧。此外，mTOR信号通过转录和转录后机制，以引发最大的精氨酸诱导的内皮炎症，先于atherosclerosis.NEW & NOTEWORTHY雷帕霉素（mTOR）复合物1（mTORC 1）和mTORC 2哺乳动物靶蛋白都有助于人类主动脉内皮细胞中PKC-α的激活。在影响人主动脉内皮细胞信号传导方面，mTOR的抑制不等同于mTORC 1和/或mTORC 2的破坏。具体而言，mTOR的抑制导致PKC-α激活和miR-200 a-3 p上调，其独立地抑制TNF-α诱导的转录因子GATA 6表达，并随后抑制VCAM-1表达和单核细胞粘附到主动脉内皮上。
Increased expression of vascular cell adhesion molecule 1 (VCAM-1) on the aortic endothelium is an early marker of atherogenesis, promoted in part by elevated levels of inflammatory cytokines such as TNF-alpha. Mammalian target of rapamycin (mTOR) is a ubiquitous signaling molecule that has been considered to contribute to diverse cellular processes through mTOR complex 1 (mTORC1) or complex 2 (mTORC2). This study aimed to elucidate the role of mTOR signaling in TNF-alpha-induced VCAM-1 expression by the arterial endothelium. Primary human aortic endothelial cells (HAECs) were treated with low-dose (0.1 ng/ml) TNF-alpha, and VCAM-1 expression was measured by real-time quantitative PCR, Western blot analysis, and flow cytometry. Inhibition of mTOR through siRNA-mediated depletion or treatment with chemical inhibitors rapamycin or torin 1 suppressed VCAM1 transcription, which translated to inhibition of VCAM-1 surface expression by HAECs and concomitant decreased adhesion of monocytes. A promoter luciferase assay and chromatin immunoprecipitation indicated that mTOR regulated VCAM1 transcription through a mechanism involving transcription factor GATA6. Activation of PKC-alpha and an increase in milt-200a-3p expression, caused by mTOR inhibition but not disruption of mTORC1 or mTORC2 singly or together, decreased TNF-ainduced GATA6 expression and its enrichment at the VCAM1 promoter. In conclusion, mTOR inhibition activates PKC-alpha independently of disruption of mTORC1 and/or mTORC2, which challenges the conventional wisdom regarding mTOR signaling. Moreover, mTOR signals through transcriptional and posttranscriptional mechanisms to elicit maximal cytokine-induced endothelial inflammation that precedes atherosclerosis.NEW & NOTEWORTHY Both mammalian target of rapamycin (mTOR) complex 1 (mTORC1) and mTORC2 contribute to PKC-alpha activation in the human aortic endothelium. Inhibition of mTOR is not equivalent to disruption of mTORC1 and/or mTORC2 in affecting human aortic endothelial cell signaling. Specifically, inhibition of mTOR causes PKC-alpha activation and miR-200a-3p upregulation, which independently suppresses TNF-alpha-induced transcription factor GATA6 expression and subsequently inhibits VCAM-1 expression and monocytic cell adhesion onto the aortic endothelium.