Department of Obstetrics and Gynecology, University of Wisconsin, Madison, Wisconsin.
Biol Reprod. 2013 May 9;88(5):114. doi: 10.1095/biolreprod.113.108225. Print 2013 May.
Endothelial cells chronically reside in low-O2 environments in vivo (2%-13% O2), which are believed to be critical for cell homeostasis. To elucidate the roles of this physiological chronic normoxia in human endothelial cells, we examined transcriptomes of human umbilical vein endothelial cells (HUVECs), proliferation and migration of HUVECs in response to fibroblast growth factor 2 (FGF2) and vascular endothelial growth factor A (VEGFA), and underlying signaling mechanisms under physiological chronic normoxia. Immediately after isolation, HUVECs were cultured steadily under standard cell culture normoxia (SCN; 21% O2) or physiological chronic normoxia (PCN; 3% O2) up to 25 days. We found that PCN up-regulated 41 genes and down-regulated 21 genes, 90% of which differed from those previously reported from HUVECs cultured under SCN and exposed to acute low O2. Gene ontology analysis indicated that PCN-regulated genes were highly related to cell proliferation and migration, consistent with the results from benchtop assays that showed that PCN significantly enhanced FGF2- and VEGFA-stimulated cell proliferation and migration. Interestingly, preexposing the PCN cells to 21% O2 up to 5 days did not completely diminish PCN-enhanced cell proliferation and migration. These PCN-enhanced cell proliferations and migrations were mediated via augmented activation of MEK1/MEK2/ERK1/ERK2 and/or PI3K/AKT1. Importantly, these PCN-enhanced cellular responses were associated with an increase in activation of VEGFR2 but not FGFR1, without altering their expression. Thus, PCN programs endothelial cells to undergo dramatic changes in transcriptomes and sensitizes cellular proliferative and migratory responses to FGF2 and VEGFA. These PCN cells may offer a unique endothelial model, more closely mimicking the in vivo states.
内皮细胞在体内（2%-13% O2）的低氧环境中慢性驻留，这种环境被认为对细胞稳态至关重要。为了阐明这种生理慢性常氧在人内皮细胞中的作用，我们检测了人脐静脉内皮细胞（HUVEC）的转录组、HUVEC 对成纤维细胞生长因子 2（FGF2）和血管内皮生长因子 A（VEGFA）的增殖和迁移反应，以及在生理慢性常氧下的潜在信号机制。HUVEC 分离后，立即在标准细胞培养常氧（SCN；21% O2）或生理慢性常氧（PCN；3% O2）下培养至 25 天。我们发现，PCN 上调了 41 个基因，下调了 21 个基因，其中 90%的基因与之前在 SCN 培养和急性低氧暴露的 HUVEC 中报道的基因不同。基因本体分析表明，PCN 调控的基因与细胞增殖和迁移高度相关，这与台式实验的结果一致，表明 PCN 显著增强了 FGF2 和 VEGFA 刺激的细胞增殖和迁移。有趣的是，将 PCN 细胞预先暴露于 21% O2 长达 5 天并不能完全消除 PCN 增强的细胞增殖和迁移。这些 PCN 增强的细胞增殖和迁移是通过增强 MEK1/MEK2/ERK1/ERK2 和/或 PI3K/AKT1 的激活来介导的。重要的是，这些 PCN 增强的细胞反应与 VEGFR2 的激活增加有关，但与 FGFR1 无关，而不改变其表达。因此，PCN 使内皮细胞的转录组发生剧烈变化，并使细胞增殖和迁移对 FGF2 和 VEGFA 的反应变得敏感。这些 PCN 细胞可能提供了一个独特的内皮细胞模型，更接近体内状态。
