Department of Pathology, School of Medicine, Boston University Medical Campus, Boston, Massachusetts 02118.
Departments of Biomedical Engineering, Chemistry, and Medicine, Boston University, Boston, Massachusetts 02215.
J Biol Chem. 2019 Sep 13;294(37):13671-13680. doi: 10.1074/jbc.RA119.008548. Epub 2019 Jul 24.
Vascular endothelial cells respond to blood flow-induced shear stress. However, the mechanisms through which endothelial cells transduce mechanical signals to cellular responses remain poorly understood. In this report, using tensile-force assays, immunofluorescence and atomic force microscopy, we demonstrate that immunoglobulin and proline-rich receptor-1 (IGPR-1) responds to mechanical stimulation and increases the stiffness of endothelial cells. We observed that IGPR-1 is activated by shear stress and tensile force and that flow shear stress-mediated IGPR-1 activation modulates remodeling of endothelial cells. We found that under static conditions, IGPR-1 is present at the cell-cell contacts; however, under shear stress, it redistributes along the cell borders into the flow direction. IGPR-1 activation stimulated actin stress fiber assembly and cross-linking with vinculin. Moreover, we noted that IGPR-1 stabilizes cell-cell junctions of endothelial cells as determined by staining of cells with ZO1. Mechanistically, shear stress stimulated activation of AKT Ser/Thr kinase 1 (AKT1), leading to phosphorylation of IGPR-1 at Ser-220. Inhibition of this phosphorylation prevented shear stress-induced actin fiber assembly and endothelial cell remodeling. Our findings indicate that IGPR-1 is an important player in endothelial cell mechanosensing, insights that have important implications for the pathogenesis of common maladies, including ischemic heart diseases and inflammation.
血管内皮细胞对血流诱导的切应力做出反应。然而,内皮细胞将机械信号转导为细胞反应的机制仍知之甚少。在本报告中,我们使用拉伸力测定、免疫荧光和原子力显微镜,证明免疫球蛋白和富含脯氨酸受体-1(IGPR-1)对机械刺激做出响应,并增加内皮细胞的硬度。我们观察到,IGPR-1 被切应力和拉伸力激活,并且流动切应力介导的 IGPR-1 激活调节内皮细胞的重塑。我们发现,在静态条件下,IGPR-1 存在于细胞-细胞连接处;然而,在切应力下,它沿着细胞边界重新分布到流动方向。IGPR-1 激活刺激肌动蛋白应力纤维组装,并与 vinculin 交联。此外,我们注意到 IGPR-1 稳定内皮细胞的细胞-细胞连接,这可以通过用 ZO1 对细胞进行染色来确定。从机制上讲,切应力刺激 AKT Ser/Thr 激酶 1(AKT1)的激活,导致 IGPR-1 在 Ser-220 位点磷酸化。抑制这种磷酸化可防止切应力诱导的肌动蛋白纤维组装和内皮细胞重塑。我们的研究结果表明,IGPR-1 是内皮细胞机械感受器中的一个重要参与者,这些发现对包括缺血性心脏病和炎症在内的常见疾病的发病机制具有重要意义。