Laboratory of Experimental Medicine (ULB 222 Unit), CHU de Charleroi, A. Vésale Hospital, Université Libre de Bruxelles, Montigny-le-Tilleul, Belgium; Laboratory of Cancer Biology and Molecular Immunology, Lebanese University, Faculty of Sciences, Hadath-Beirut, Lebanon.
Laboratory of Molecular Biology of Inflammation, IBMM, Faculty of Sciences, Université Libre de Bruxelles, Gosselies, Belgium.
Atherosclerosis. 2018 Dec;279:73-87. doi: 10.1016/j.atherosclerosis.2018.10.023. Epub 2018 Oct 19.
Endothelial cells are main actors in vascular homeostasis as they regulate vascular pressure and permeability as well as hemostasis and inflammation. Disturbed stimuli delivered to and by endothelial cells correlate with the so-called endothelial dysfunction and disrupt this homeostasis. As constituents of the inner layer of blood vessels, endothelial cells are also involved in angiogenesis. Apolipoprotein Ls (APOL) comprise a family of newly discovered apolipoproteins with yet poorly understood function, and are suggested to be involved in inflammatory processes and cell death mechanisms. Here we investigate the role of APOLs in endothelial cells stimulated with factors known to be involved in atherogenesis and their possible contribution to endothelial dysfunction with an emphasis on inflammation driven-angiogenesis in vitro.
Using the CRISPR/Cas9 technique, we analyzed the effect of APOL3 gene knock out in HMEC-1 endothelial cells on cell migration, tubulogenesis, endothelial permeability, intracellular signal transduction as assessed by kinase phosphorylation, and angiogenesis gene expression (measured by qRT-PCR).
Our results indicate that among the family, APOL3 was the only member induced by myeloperoxidase, oxidized LDL, VEGF and FGF treatments. APOL3 invalidation increased endothelial permeability, reduced wound repair and tubule formation in vitro, the latter only in MPO and VEGF-induced conditions. Accordingly, some pro-angiogenic signaling pathways (ERK1/2 and FAK but not Akt) and some pro-angiogenic genes were partially inhibited in APOL3 knock out cells.
These findings suggest the involvement of APOL3 in angiogenesis in vitro and as a modulator of MAPK and FAK signaling in endothelial cells.
内皮细胞是血管稳态的主要参与者，因为它们调节血管压力和通透性以及止血和炎症。内皮细胞受到的和向其传递的受干扰的刺激与所谓的内皮功能障碍相关，并破坏这种稳态。作为血管内层的组成部分，内皮细胞也参与血管生成。载脂蛋白 Ls（APOL）是一组新发现的载脂蛋白，其功能尚未完全了解，据推测它们参与炎症过程和细胞死亡机制。在这里，我们研究了 APOL 在受已知参与动脉粥样硬化形成的因子刺激的内皮细胞中的作用，以及它们在体外炎症驱动的血管生成中的内皮功能障碍中的可能作用。
使用 CRISPR/Cas9 技术，我们分析了 APOL3 基因敲除对 HMEC-1 内皮细胞细胞迁移、小管形成、内皮通透性、细胞内信号转导（通过激酶磷酸化评估）和血管生成基因表达（通过 qRT-PCR 测量）的影响。
我们的结果表明，在该家族中，APOL3 是唯一被髓过氧化物酶、氧化 LDL、VEGF 和 FGF 处理诱导的成员。APOL3 无效增加了内皮通透性，减少了体外的伤口修复和小管形成，后者仅在 MPO 和 VEGF 诱导的条件下发生。因此，一些促血管生成信号通路（ERK1/2 和 FAK，但不是 Akt）和一些促血管生成基因在 APOL3 敲除细胞中部分受到抑制。
这些发现表明 APOL3 参与了体外血管生成，并且是内皮细胞中 MAPK 和 FAK 信号通路的调节剂。
