Xu Jing, Jiang Congshan, Cai Yongsong, Guo Yuanxu, Wang Xipeng, Zhang Jiaxiang, Xu Jiawen, Xu Ke, Zhu Wenhua, Wang Si, Zhang Fujun, Geng Manman, Han Yan, Ning Qilan, Xu Peng, Meng Liesu, Lu Shemin
Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, 710061, Shaanxi, People's Republic of China.
Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an, 710061, Shaanxi, People's Republic of China.
Arthritis Res Ther. 2020 Aug 31;22(1):200. doi: 10.1186/s13075-020-02296-8.
The disruption of metabolic events and changes to nutrient and oxygen availability due to sustained inflammation in RA increases the demand of bioenergetic and biosynthetic processes within the damaged tissue. The current study aimed to understand the molecular mechanisms of SLC7A5 (amino acid transporter) in synoviocytes of RA patients.
Synovial tissues were obtained from OA and RA patients. Fibroblast-like synoviocytes (FLS) were isolated, and SLC7A5 expression was examined by using RT-qPCR, immunofluorescence, and Western blotting. RNAi and antibody blocking treatments were used to knockdown SLC7A5 expression or to block its transporter activities. mTOR activity assay and MMP expression levels were monitored in RA FLS under amino acid deprivation or nutrient-rich conditions.
RA FLS displayed significantly upregulated expression of SLC7A5 compared to OA FLS. Cytokine IL-1β was found to play a crucial role in upregulating SLC7A5 expression via the NF-κB pathway. Intervening SLC7A5 expression with RNAi or blocking its function by monoclonal antibody ameliorated MMP3 and MMP13 protein expression. Conversely, upregulation of SLC7A5 or tryptophan supplementation enhanced mTOR-P70S6K signals which promoted the protein translation of MMP3 and MMP13 in RA FLS.
Activated NF-κB pathway upregulates SLC7A5, which enhances the mTOR-P70S6K activity and MMP3 and MMP13 expression in RA FLS.
类风湿关节炎（RA）中持续炎症导致的代谢事件紊乱以及营养物质和氧气供应的改变，增加了受损组织内生物能量和生物合成过程的需求。本研究旨在了解RA患者滑膜细胞中溶质载体家族7成员5（SLC7A5，氨基酸转运体）的分子机制。
从骨关节炎（OA）和RA患者获取滑膜组织。分离出成纤维样滑膜细胞（FLS），采用逆转录定量聚合酶链反应（RT-qPCR）、免疫荧光和蛋白质免疫印迹法检测SLC7A5的表达。使用RNA干扰（RNAi）和抗体阻断处理来敲低SLC7A5的表达或阻断其转运活性。在氨基酸缺乏或营养丰富条件下，监测RA-FLS中的雷帕霉素靶蛋白（mTOR）活性测定和基质金属蛋白酶（MMP）表达水平。
与OA-FLS相比，RA-FLS中SLC7A5的表达显著上调。发现细胞因子白细胞介素-1β（IL-1β）通过核因子κB（NF-κB）途径在上调SLC7A5表达中起关键作用。用RNAi干预SLC7A5表达或用单克隆抗体阻断其功能可改善MMP3和MMP13蛋白表达。相反，SLC7A5的上调或色氨酸补充增强了mTOR-P70核糖体蛋白S6激酶（P70S6K）信号，促进了RA-FLS中MMP3和MMP13的蛋白质翻译。
活化的NF-κB途径上调SLC7A5，增强RA-FLS中的mTOR-P70S6K活性以及MMP3和MMP13表达。
