Department of Cardiology, Guangzhou Red Cross Hospital, Jinan University, Guangzhou, 510220, China.
Department of Cardiology, Laboratory of Heart Center, Zhujiang Hospital, Southern Medical University, Guangdong Provincial Key Laboratory of Cardiac Function and Microcirculation, Guangdong Provincial Biomedical Engineering Technology Research Center for Cardiovascular Disease, Guangzhou, 510280, China.
Exp Cell Res. 2024 Jun 1;439(1):114071. doi: 10.1016/j.yexcr.2024.114071. Epub 2024 May 8.
Atherosclerosis preferentially occurs in areas with low shear stress (LSS) and oscillatory flow. LSS has been demonstrated to correlate with the development of atherosclerosis. The sphingosine 1-phosphate receptor 1 (S1PR1), involving intravascular blood flow sensing, regulates vascular development and vascular barrier function. However, whether LSS affects atherosclerosis via regulating S1PR1 remains incompletely clear. In this study, immunostaining results of F-actin, β-catenin, and VE-cadherin indicated that LSS impaired endothelial barrier function in human umbilical vein endothelial cells (HUVECs). Western blot analysis showed that LSS resulted in blockage of autophagic flux in HUVECs. In addition, autophagy agonist Rapamycin (Rapa) antagonized LSS-induced endothelial barrier dysfunction, whereas autophagic flux inhibitor Bafilomycin A1 (BafA1) exacerbated it, indicating that LSS promoted endothelial barrier dysfunction by triggering autophagic flux blockage. Notably, gene expression analysis revealed that LSS downregulated S1PR1 expression, which was antagonized by Rapa. Selective S1PR1 antagonist W146 impaired endothelial barrier function of HUVECs under high shear stress (HSS) conditions. Moreover, our data showed that expression of GAPARAPL2, a member of autophagy-related gene 8 (Atg8) proteins, was decreased in HUVECs under LSS conditions. Autophagic flux blockage induced by GAPARAPL2 knockdown inhibited S1PR1, aggravated endothelial barrier dysfunction of HUVECs in vitro, and promoted aortic atherosclerosis in ApoE mice in vivo. Our study demonstrates that autophagic flux blockage induced by LSS downregulates S1PR1 expression and impairs endothelial barrier function. GABARAPL2 inhibition is involved in LSS-induced autophagic flux blockage, which impairs endothelial barrier function via downregulation of S1PR1.
动脉粥样硬化易发生于低切应力（LSS）和振荡流的区域。已证实低切应力与动脉粥样硬化的发展相关。鞘氨醇 1-磷酸受体 1（S1PR1）参与血管内血流感应，调节血管发育和血管屏障功能。然而，低切应力是否通过调节 S1PR1 影响动脉粥样硬化尚不完全清楚。在这项研究中，F-肌动蛋白、β-连环蛋白和 VE-钙黏蛋白的免疫染色结果表明，低切应力会损害人脐静脉内皮细胞（HUVECs）的内皮屏障功能。Western blot 分析显示，低切应力导致 HUVECs 中的自噬流受阻。此外，自噬激动剂雷帕霉素（Rapa）拮抗了低切应力诱导的内皮屏障功能障碍，而自噬流抑制剂巴弗洛霉素 A1（BafA1）则加剧了这种障碍，表明低切应力通过触发自噬流受阻促进了内皮屏障功能障碍。值得注意的是，基因表达分析显示，低切应力下调了 S1PR1 的表达，而 Rapa 拮抗了这种下调。选择性 S1PR1 拮抗剂 W146 在高切应力（HSS）条件下损害了 HUVECs 的内皮屏障功能。此外，我们的数据显示，在低切应力条件下，自噬相关基因 8（Atg8）蛋白家族成员 GAPARAPL2 的表达在 HUVECs 中减少。GAPARAPL2 敲低诱导的自噬流受阻抑制了 S1PR1，加剧了体外 HUVECs 的内皮屏障功能障碍，并促进了体内 ApoE 小鼠的主动脉粥样硬化。我们的研究表明，低切应力诱导的自噬流受阻下调了 S1PR1 的表达，损害了内皮屏障功能。GABARAPL2 抑制参与了低切应力诱导的自噬流受阻，通过下调 S1PR1 损害内皮屏障功能。
