Department of Pediatrics, Yale University School of Medicine, New Haven, CT, 06520, USA.
Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, CT, 06520, USA.
Angiogenesis. 2021 Aug;24(3):631-645. doi: 10.1007/s10456-021-09773-x. Epub 2021 Mar 2.
The glucocorticoid receptor (GR) is a member of the nuclear receptor family that controls key biological processes in the cardiovascular system and has recently been shown to modulate Wnt signaling in endothelial cells. Wnt/β-catenin signaling has been demonstrated to be crucial in the process of angiogenesis. In the current study, we studied whether GR could regulate angiogenesis via the Wnt/β-catenin pathway.
Key components of the Wnt/β-catenin pathway were evaluated using quantitative PCR and Western blot in the presence or absence of GR. Enhanced angiogenesis was found in GR deficiency in vitro and confirmed with cell viability assays, proliferation assays and tube formation assays. Consistent with these in vitro findings, endothelial cell-specific GR loss GR in vivo promoted angiogenesis in both a hind limb ischemia model and sponge implantation assay. Results were further verified in a novel mouse model lacking endothelial LRP5/6, a key receptor in canonical Wnt signaling, and showed substantially suppressed angiogenesis using these same in vitro and in vivo assays. To further investigate the mechanism of GR regulation of Wnt signaling, autophagy flux was investigated in endothelial cells by visualizing auto phagolysosomes as well as by assessing P62 degradation and LC3B conversion. Results indicated that potentiated autophagy flux participated in GR-Wnt regulation.
Lack of endothelial GR triggers autophagy flux, leads to activation of Wnt/β-catenin signaling and promotes angiogenesis. There may also be a synergistic interaction between autophagy and Wnt/β-catenin signaling.
糖皮质激素受体（GR）是核受体家族的一员，它控制着心血管系统中的关键生物过程，最近被证明可以调节内皮细胞中的 Wnt 信号。Wnt/β-连环蛋白信号已被证明在血管生成过程中至关重要。在本研究中，我们研究了 GR 是否可以通过 Wnt/β-连环蛋白途径来调节血管生成。
在存在或不存在 GR 的情况下，使用定量 PCR 和 Western blot 评估了 Wnt/β-连环蛋白途径的关键组成部分。在体外 GR 缺乏时发现血管生成增强，并通过细胞活力测定、增殖测定和管形成测定得到证实。与这些体外发现一致的是，内皮细胞特异性 GR 缺失（GR 在体内）促进了后肢缺血模型和海绵植入试验中的血管生成。在缺乏内皮 LRP5/6 的新型小鼠模型（经典 Wnt 信号的关键受体）中进一步验证了结果，使用相同的体外和体内测定方法，发现血管生成受到显著抑制。为了进一步研究 GR 调节 Wnt 信号的机制，通过可视化自噬溶酶体以及评估 P62 降解和 LC3B 转化，研究了内皮细胞中自噬通量。结果表明，增强的自噬通量参与了 GR-Wnt 调节。
内皮细胞缺乏 GR 会触发自噬通量，导致 Wnt/β-连环蛋白信号激活并促进血管生成。自噬和 Wnt/β-连环蛋白信号之间可能存在协同相互作用。
