Werner Ann-Cathrin, Weckbach Ludwig T, Salvermoser Melanie, Pitter Bettina, Cao Jiahui, Maier-Begandt Daniela, Forné Ignasi, Schnittler Hans-Joachim, Walzog Barbara, Montanez Eloi
Institute of Cardiovascular Physiology and Pathophysiology, Biomedical Center, LMU Munich, Munich, Germany.
Walter Brendel Center of Experimental Medicine, University Hospital, LMU Munich, Munich, Germany.
Front Cell Dev Biol. 2020 Jul 31;8:708. doi: 10.3389/fcell.2020.00708. eCollection 2020.
Development and homeostasis of blood vessels critically depend on the regulation of endothelial cell-cell junctions. VE-cadherin (VEcad)-based cell-cell junctions are connected to the actin cytoskeleton and regulated by actin-binding proteins. Coronin 1B (Coro1B) is an actin binding protein that controls actin networks at classical lamellipodia. The role of Coro1B in endothelial cells (ECs) is not fully understood and investigated in this study. Here, we demonstrate that Coro1B is a novel component and regulator of cell-cell junctions in ECs. Immunofluorescence studies show that Coro1B colocalizes with VEcad at cell-cell junctions in monolayers of ECs. Live-cell imaging reveals that Coro1B is recruited to, and operated at actin-driven membrane protrusions at cell-cell junctions. Coro1B is recruited to cell-cell junctions via a mechanism that requires the relaxation of the actomyosin cytoskeleton. By analyzing the Coro1B interactome, we identify integrin-linked kinase (ILK) as new Coro1B-associated protein. Coro1B colocalizes with α-parvin, an interactor of ILK, at the leading edge of lamellipodia protrusions. Functional experiments reveal that depletion of Coro1B causes defects in the actin cytoskeleton and cell-cell junctions. Finally, in matrigel tube network assays, depletion of Coro1B results in reduced network complexity, tube number and tube length. Together, our findings point toward a critical role for Coro1B in the dynamic remodeling of endothelial cell-cell junctions and the assembly of endothelial networks.
血管的发育和稳态严重依赖于内皮细胞间连接的调控。基于血管内皮钙黏蛋白（VE-cadherin，VEcad）的细胞间连接与肌动蛋白细胞骨架相连，并受肌动蛋白结合蛋白的调控。冠蛋白1B（Coronin 1B，Coro1B）是一种肌动蛋白结合蛋白，可控制经典板状伪足处的肌动蛋白网络。Coro1B在内皮细胞（ECs）中的作用尚未完全明确，本研究对此进行了探究。在此，我们证明Coro1B是ECs中细胞间连接的一种新型组成成分和调控因子。免疫荧光研究表明，在ECs单层细胞的细胞间连接处，Coro1B与VEcad共定位。活细胞成像显示，Coro1B被招募至细胞间连接处由肌动蛋白驱动的膜突起部位并在该处发挥作用。Coro1B通过一种需要肌动球蛋白细胞骨架松弛的机制被招募至细胞间连接处。通过分析Coro1B相互作用组，我们鉴定出整合素连接激酶（ILK）是一种新的与Coro1B相关的蛋白。Coro1B与ILK的相互作用分子α-帕文（α-parvin）在板状伪足突起的前沿共定位。功能实验表明，Coro1B的缺失会导致肌动蛋白细胞骨架和细胞间连接出现缺陷。最后，在基质胶管网络测定中，Coro1B的缺失导致网络复杂性、管数量和管长度降低。总之，我们的研究结果表明Coro1B在内皮细胞间连接的动态重塑和内皮网络组装中起关键作用。
