Department of Cardiology, Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Zhengzhou, China.
Department of Cardiology, Central China Fuwai Hospital, Zhengzhou, China.
FASEB J. 2023 Aug;37(8):e23085. doi: 10.1096/fj.202300665R.
Endoplasmic reticulum (ER) stress is closely associated with atherosclerosis (AS). Nevertheless, the regulatory mechanism of ER stress in endothelial cells during AS progression is unclear. Here, the role and regulatory mechanism of DNA (cytosine-5-)- methyltransferase 3 beta (DNMT3B) in ER stress during AS progression were investigated. ApoE mice were fed with high fat diet to construct AS model in vivo. HE and Masson staining were performed to analyze histopathological changes and collagen deposition. HUVECs stimulated by ox-LDL were used as AS cellular model. Cell apoptosis was examined using flow cytometry. DCFH-DA staining was performed to examine ROS level. The levels of pro-inflammatory cytokines were assessed using ELISA. In addition, MSP was employed to detect PTPN2 promoter methylation level. Our results revealed that DNMT3B and FGFR3 were significantly upregulated in AS patient tissues, whereas PTPN2 was downregulated. PTPN2 overexpression attenuate ox-LDL-induced ER stress, inflammation and apoptosis in HUVECs and ameliorated AS symptoms in vivo. PTPN2 could suppress FGFR3 expression in ox-LDL-treated HUVECs, and FGFR3 knockdown inhibited ER stress to attenuate ox-LDL-induced endothelial cell apoptosis. DNMT3B could negatively regulate PTPN2 expression and positively FGFR2 expression in ox-LDL-treated HUVECs; DNMT3B activated FGFR2 expression by increasing PTPN2 promoter methylation level. DNMT3B downregulation repressed ox-LDL-induced ER stress, inflammation and cell apoptosis in endothelial cells, which was reversed by PTPN2 silencing. DNMT3B activated FGFR3-mediated ER stress by increasing PTPN2 promoter methylation level and suppressed its expression, thereby boosting ER stress to facilitate AS progression.
内质网（ER）应激与动脉粥样硬化（AS）密切相关。然而，AS 进展过程中内皮细胞 ER 应激的调节机制尚不清楚。本研究旨在探讨 DNA（胞嘧啶-5）-甲基转移酶 3β（DNMT3B）在 AS 进展过程中 ER 应激中的作用及其调控机制。通过给予载脂蛋白 E（ApoE）基因敲除小鼠高脂饮食构建体内 AS 模型，采用 HE 和 Masson 染色观察组织病理学变化和胶原沉积，采用氧化型低密度脂蛋白（ox-LDL）刺激人脐静脉内皮细胞（HUVEC）构建 AS 细胞模型，采用流式细胞术检测细胞凋亡，采用 DCFH-DA 染色检测活性氧（ROS）水平，采用 ELISA 检测促炎细胞因子水平，此外，采用 MSP 检测 PTPN2 启动子甲基化水平。结果显示，DNMT3B 和 FGFR3 在 AS 患者组织中显著上调，而 PTPN2 下调。过表达 PTPN2 可减轻 ox-LDL 诱导的 HUVECs 中 ER 应激、炎症和凋亡，并改善体内 AS 症状。PTPN2 可抑制 ox-LDL 处理的 HUVECs 中 FGFR3 的表达，而 FGFR3 敲低可抑制 ER 应激从而减轻 ox-LDL 诱导的内皮细胞凋亡。DNMT3B 可负向调控 ox-LDL 处理的 HUVECs 中 PTPN2 的表达和正向调控 FGFR2 的表达；DNMT3B 通过增加 PTPN2 启动子甲基化水平激活 FGFR2 表达。DNMT3B 下调可抑制内皮细胞中 ox-LDL 诱导的 ER 应激、炎症和细胞凋亡，而 PTPN2 沉默可逆转这一作用。DNMT3B 通过增加 PTPN2 启动子甲基化水平抑制其表达，从而激活 FGFR3 介导的 ER 应激，促进 AS 进展。
