Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia and Charlie Norwood VA Medical Center, Augusta, GA 30912, United States.
Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia and Charlie Norwood VA Medical Center, Augusta, GA 30912, United States; Department of Medicine, Vascular Biology Center and Cancer Center, Augusta University, Augusta, GA 30912, United States.
Biochem Pharmacol. 2019 Jun;164:205-215. doi: 10.1016/j.bcp.2019.04.016. Epub 2019 Apr 13.
Endothelial to mesenchymal transition (EndMT), where endothelial cells acquire mesenchymal characteristics has been implicated in several cardiopulmonary, vascular and fibrotic diseases. The most commonly studied molecular mechanisms involved in EndMT include TGFβ, Notch, interleukin, and interferon-γ signaling. As of today, the contributions of Akt1, an important mediator of TGFβ signaling and a key regulator of endothelial barrier function to EndMT remains unclear. By using the ShRNA based gene silencing approach and endothelial-specific inducible Akt1 knockdown (ECKO) mice, we studied the role of Akt1 in EndMT in vitro and pathological vascular remodeling in vivo. Stable, Akt1 silenced (ShAkt1) human microvascular endothelial cells (HMECs) indicated increased expression of mesenchymal markers such as N-cadherin and α-SMA, phosphorylation of Smad2/3, cellular stress via activation of p38 MAP Kinase and the loss of endothelial nitric oxide synthase (eNOS) accompanied by a change in the morphology of HMECs in vitro and co-localization of endothelial and mesenchymal markers promoting EndMT in vivo. EndMT as a result of Akt1 loss was associated with increased expression of TGFβ2, a potent inducer of EndMT and mesenchymal transcription factors Snail1, and FoxC2. We observed that hypoxia-induced lung vascular remodeling is exacerbated in ECKO mice, which was reversed by pharmacological inhibition of β-catenin. Thus, we provide novel insights into the role of Akt1-mediated β-catenin signaling in EndMT and pathological vascular remodeling, and present β-catenin as a potential target for therapy for various cardiopulmonary diseases involving vascular remodeling.
内皮到间充质转化（EndMT），即内皮细胞获得间充质特征，与几种心肺、血管和纤维化疾病有关。目前研究最多的涉及 EndMT 的分子机制包括 TGFβ、Notch、白细胞介素和干扰素-γ信号通路。截至目前，TGFβ 信号的重要介质 Akt1 和内皮屏障功能的关键调节因子 Akt1 对 EndMT 的贡献尚不清楚。通过使用基于 shRNA 的基因沉默方法和内皮特异性诱导 Akt1 敲低（ECKO）小鼠，我们研究了 Akt1 在体外 EndMT 和体内病理性血管重塑中的作用。稳定的、Akt1 沉默的（ShAkt1）人微血管内皮细胞（HMEC）表明，间充质标志物如 N-钙粘蛋白和α-SMA 的表达增加，Smad2/3 的磷酸化，通过激活 p38 MAP 激酶引起的细胞应激，以及内皮型一氧化氮合酶（eNOS）的丢失，伴有 HMEC 体外形态的变化和内皮和间充质标志物的共定位，促进体内 EndMT。Akt1 缺失导致的 EndMT 与 TGFβ2 的表达增加有关，TGFβ2 是 EndMT 和间充质转录因子 Snail1 和 FoxC2 的有效诱导物。我们观察到，ECKO 小鼠中的缺氧诱导的肺血管重塑加剧，这可以通过β-连环蛋白的药理学抑制来逆转。因此，我们提供了 Akt1 介导的β-连环蛋白信号在 EndMT 和病理性血管重塑中的作用的新见解，并提出β-连环蛋白作为涉及血管重塑的各种心肺疾病治疗的潜在靶点。
