Thoracic Surgery Laboratory, Xuzhou Medical University, Xuzhou 221006, China.
Department of Thoracic Surgery, Affiliated Hospital of Xuzhou Medical University, Xuzhou 221006, China.
Int J Mol Sci. 2023 Feb 1;24(3):2787. doi: 10.3390/ijms24032787.
Maintaining the integrity and protecting the stability of tight junctions in endothelial cells is a potential therapeutic strategy against myocardial ischaemia. Laminin receptors (67LR) are highly expressed on endothelial cell membranes and are associated with endothelial barrier function. Herein, we sought to demonstrate the direct effects of pigment epithelial-derived factor (PEDF) on tight junctions between endothelial cells via 67LR during acute myocardial infarction (AMI) and elucidate its underlying mechanisms. We detected that PEDF directly increased the level of the tight junction protein zonula occludens protein 1 (ZO-1) after overexpression in vitro and in vivo using Western blotting. Evans Blue/TTC staining showed that PEDF significantly reduced the size of the infarcted myocardium. Immunofluorescence and the transwell cellular experiments suggested that PEDF significantly upregulated PI3K-AKT permeability and the distribution of ZO-1 between endothelial cells under OGD conditions. Interestingly, PEDF significantly upregulated the phosphorylation levels of PI3K-AKT-mTOR under oxygen and glucose deprivation conditions but had no significant effects on the total protein expression. The protective effect of PEDF on ZO-1 was significantly inhibited following the inhibition of PI3K-AKT-mTOR. The activation of phosphorylation of PI3K-AKT-mTOR by PEDF was blocked after silencing 67LR, as were the protective effects of PEDF on ZO-1. Therefore, we have reason to believe that PEDF increased ZO-1 expression through the 67LR-dependent PI3K-AKT-mTOR signaling pathway, thus maintaining tight junction stability and protecting cardiac function.
维持内皮细胞紧密连接的完整性和稳定性是防治心肌缺血的潜在治疗策略。层粘连蛋白受体（67LR）在血管内皮细胞的细胞膜上高度表达，并与内皮屏障功能有关。在此，我们旨在通过 67LR 证明在急性心肌梗死（AMI）期间 PEDF 对内皮细胞之间紧密连接的直接作用，并阐明其潜在机制。我们通过 Western blot 检测到 PEDF 在体外和体内过表达后直接增加了紧密连接蛋白闭合蛋白 1（ZO-1）的水平。伊文思蓝/TTC 染色表明 PEDF 显著减少了梗死心肌的大小。免疫荧光和 Transwell 细胞实验表明，在 OGD 条件下，PEDF 显著上调了 PI3K-AKT 通透性和 ZO-1 在血管内皮细胞之间的分布。有趣的是，在氧葡萄糖剥夺条件下，PEDF 显著上调了 PI3K-AKT-mTOR 的磷酸化水平，但对总蛋白表达没有显著影响。PI3K-AKT-mTOR 的抑制显著抑制了 PEDF 对 ZO-1 的保护作用。沉默 67LR 后，PEDF 对 PI3K-AKT-mTOR 磷酸化的激活作用被阻断，PEDF 对 ZO-1 的保护作用也被阻断。因此，我们有理由相信，PEDF 通过 67LR 依赖性 PI3K-AKT-mTOR 信号通路增加 ZO-1 的表达，从而维持紧密连接的稳定性并保护心脏功能。
