Center for Vascular Biology Research, Division of Molecular and Vascular Biology, and Department of Gastroenterology, Provincial Hospital Affiliated to Shandong University, Ji-nan, China;
Center for Vascular Biology Research, Division of Molecular and Vascular Biology, and Department of Hepatobiliary Surgery and Department of General Surgery, the First Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an, China; and.
FASEB J. 2014 Oct;28(10):4524-33. doi: 10.1096/fj.13-248401. Epub 2014 Jul 11.
Angiogenesis is a hallmark of many diseases, including cancer, ischemic heart disease, inflammation, and others. It is well known that vascular endothelial growth factor (VEGF) is the most important angiogenic factor. Recently, we demonstrated that orphan nuclear receptor TR3 (mouse Nur77 and rat NGFI-B) plays critical roles in tumor growth and angiogenesis induced by VEGF-A in vitro and in vivo. However, the signaling pathways that mediate the expression of TR3 induced by VEGF are still not completely understood. Here we reported that 3 TR3 transcript variants (TR3-TVs) are expressed at differential levels, and regulated differentially in endothelial cells. While the expression of TR3-TV1 is relatively low, the expression of TR3-TV2 is up-regulated markedly, and the expression of TR3-TV3 is up-regulated moderately in endothelial cells induced by VEGF-A. The kinetics of the induction of these TR3-TVs is different. We also found that several signaling pathways, including calcium-PLC-PKC-PKD1 pathway, NF-κB pathway, and MAP kinase (ERK, p38, and JNK) pathways are important for VEGF-A-induced TR3-TV2 and TR3-TV3 mRNA induction. More important, we found that VEGF-A or VEGF-E, but not VEGF-B, nor placenta growth factor (PlGF), induces the phosphorylation of insulin-like growth factor-1 receptor (IGF-1R) and the interaction of VEGF receptor 2/kinase insert domain receptor (VEGFR2/KDR) with IGF-1R, which mediates the expression of TR3-TV2, but not TR3-TV3. Taking together, we demonstrate that TR3-TVs are differentially regulated by VEGF-A and identify a novel signaling pathway by which VEGF-A and VEGF-E, but neither VEGF-B, nor PlGF, induce the interaction of VEGFR2/KDR with IGF-1R, resulting in IGF-1R transactivation to induce the high level expression of TR3-TV2. Our data not only elucidate the signaling pathways by which TR3-TVs are regulated, but extend the molecular mechanism, by which VEGF-A-induced angiogenesis. These studies should permit the development of screening assays for compounds that inhibit VEGF signaling.
血管生成是许多疾病的标志，包括癌症、缺血性心脏病、炎症等。众所周知，血管内皮生长因子（VEGF）是最重要的血管生成因子。最近，我们证明了孤儿核受体 TR3（小鼠 Nur77 和大鼠 NGFI-B）在体外和体内的 VEGF-A 诱导的肿瘤生长和血管生成中发挥关键作用。然而，介导 VEGF 诱导的 TR3 表达的信号通路仍不完全清楚。在这里，我们报道了 3 种 TR3 转录变体（TR3-TVs）以不同水平表达，并在血管内皮细胞中差异调节。虽然 TR3-TV1 的表达相对较低，但 TR3-TV2 的表达显著上调，TR3-TV3 的表达中度上调在 VEGF-A 诱导的血管内皮细胞中。这些 TR3-TVs 的诱导动力学不同。我们还发现，几种信号通路，包括钙-PLC-PKC-PKD1 通路、NF-κB 通路和 MAP 激酶（ERK、p38 和 JNK）通路，对 VEGF-A 诱导的 TR3-TV2 和 TR3-TV3 mRNA 诱导很重要。更重要的是，我们发现 VEGF-A 或 VEGF-E，但不是 VEGF-B，也不是胎盘生长因子（PlGF），诱导胰岛素样生长因子-1 受体（IGF-1R）的磷酸化和 VEGF 受体 2/激酶插入结构域受体（VEGFR2/KDR）与 IGF-1R 的相互作用，介导 TR3-TV2 的表达，但不是 TR3-TV3。总之，我们证明了 TR3-TVs 被 VEGF-A 差异调节，并确定了一种新的信号通路，通过该通路，VEGF-A 和 VEGF-E，但不是 VEGF-B，也不是 PlGF，诱导 VEGFR2/KDR 与 IGF-1R 的相互作用，导致 IGF-1R 的转激活，从而诱导 TR3-TV2 的高水平表达。我们的数据不仅阐明了调节 TR3-TVs 的信号通路，而且扩展了 VEGF-A 诱导血管生成的分子机制。这些研究应该允许开发抑制 VEGF 信号的化合物的筛选测定。
