Goetze Stephan, Bungenstock Anne, Czupalla Cornelia, Eilers Friedrich, Stawowy Philipp, Kintscher Ulrich, Spencer-Hänsch Chantel, Graf Kristof, Nürnberg Bernd, Law Ronald E, Fleck Eckart, Gräfe Michael
Department of Medicine/Cardiology, German Heart Institute Berlin, Germany.
Hypertension. 2002 Nov;40(5):748-54. doi: 10.1161/01.hyp.0000035522.63647.d3.
Migration of endothelial cells (EC) is a key event in angiogenesis that contributes to neovascularization in diabetic vasculopathy. Leptin induces angiogenesis and is elevated in obesity and hyperinsulinemia. The antidiabetic thiazolidinediones (TZD) inhibit leptin gene expression and vascular smooth muscle cell migration through activation of the peroxisome proliferator-activated receptor-gamma (PPARgamma). This study investigates the role of leptin in EC migration, the chemotactic signaling pathways involved, and the effects of the TZD-PPARgamma ligands troglitazone (TRO) and ciglitazone (CIG) on EC migration. We demonstrate that leptin induces EC migration. Because activation of two signaling pathways, the phosphatidylinositol-3 kinase (PI3K)-->Akt-->eNOS and the ERK1/2 MAPK pathway, is known to be involved in cell migration, we used the pharmacological inhibitors wortmannin and PD98059 to determine if chemotactic signaling by leptin involves Akt or ERK1/2, respectively. Both wortmannin and PD98059 significantly inhibited leptin-induced migration. Treatment with the TZD-PPARgamma-ligands TRO and CIG significantly inhibited the chemotactic response toward leptin. Both PPARgamma-ligands inhibited leptin-stimulated Akt and eNOS phosphorylation, but neither attenuated ERK 1/2 activation in response to leptin. The inhibition of Akt-phosphorylation was accompanied by a PPARgamma-ligand-mediated upregulation of PTEN, a phosphatase that functions as a negative regulator of PI3K-->Akt signaling. These experiments provide the first evidence that activation of Akt and ERK 1/2 are crucial events in leptin-mediated signal transduction leading to EC migration. Moreover, inhibition of leptin-directed migration by the PPARgamma-ligands TRO and CIG through inhibition of Akt underscores their potential in the prevention of diabetes-associated complications.
内皮细胞（EC）迁移是血管生成中的关键事件，在糖尿病血管病变中促进新血管形成。瘦素可诱导血管生成，且在肥胖症和高胰岛素血症中水平升高。抗糖尿病药物噻唑烷二酮类（TZD）通过激活过氧化物酶体增殖物激活受体γ（PPARγ）来抑制瘦素基因表达及血管平滑肌细胞迁移。本研究调查了瘦素在EC迁移中的作用、相关趋化信号通路，以及TZD-PPARγ配体曲格列酮（TRO）和环格列酮（CIG）对EC迁移的影响。我们证明瘦素可诱导EC迁移。由于已知磷脂酰肌醇-3激酶（PI3K）→Akt→内皮型一氧化氮合酶（eNOS）和细胞外信号调节激酶1/2（ERK1/2）丝裂原活化蛋白激酶（MAPK）这两条信号通路的激活与细胞迁移有关，我们使用了药理抑制剂渥曼青霉素和PD98059来分别确定瘦素的趋化信号是否涉及Akt或ERK1/2。渥曼青霉素和PD98059均显著抑制了瘦素诱导的迁移。用TZD-PPARγ配体TRO和CIG处理可显著抑制对瘦素的趋化反应。两种PPARγ配体均抑制瘦素刺激的Akt和eNOS磷酸化，但均未减弱对瘦素的ERK1/2激活。Akt磷酸化的抑制伴随着PPARγ配体介导的磷酸酶张力蛋白同源物（PTEN）上调，PTEN作为PI3K→Akt信号的负调节因子发挥作用。这些实验首次证明Akt和ERK1/2的激活是瘦素介导的导致EC迁移的信号转导中的关键事件。此外，PPARγ配体TRO和CIG通过抑制Akt来抑制瘦素导向的迁移，突出了它们在预防糖尿病相关并发症方面的潜力。
