Francis Caitlin R, Bell Makenzie L, Skripnichuk Marina M, Kushner Erich J
Department of Biological Sciences, University of Denver, Denver, CO.
bioRxiv. 2023 Feb 22:2023.02.22.529543. doi: 10.1101/2023.02.22.529543.
Clathrin-mediated endocytosis (CME) is a process vital to angiogenesis as well as general vascular homeostasis. In pathologies where supraphysiological growth factor signaling underlies disease etiology, such as in diabetic retinopathy and solid tumors, strategies to limit chronic growth factor signaling by way of CME have been shown to have tremendous clinical value. ADP ribosylation factor 6 (Arf6) is a small GTPase that promotes the assembly of actin necessary for CME. In its absence, growth factor signaling is greatly diminished, which has been shown to ameliorate pathological signaling input in diseased vasculature. However, it is less clear if there are bystander effects related to loss of Arf6 on angiogenic behaviors. Our goal was to provide a analysis of Arf6’s function in angiogenic endothelium, focusing on its role in lumenogenesis as well as its relation to actin and CME. We found that Arf6 localized to both filamentous actin and sites of CME in 2-dimensional culture. Loss of Arf6 distorted both apicobasal polarity and reduced the total cellular filamentous actin content, and this may be the primary driver underlying gross dysmorphogenesis during angiogenic sprouting in its absence. Our findings highlight that endothelial Arf6 is a potent mediator of both actin regulation and CME.
网格蛋白介导的内吞作用（CME）是血管生成以及一般血管稳态的重要过程。在超生理生长因子信号传导是疾病病因基础的病理学中，例如在糖尿病视网膜病变和实体瘤中，通过CME限制慢性生长因子信号传导的策略已显示出巨大的临床价值。ADP核糖基化因子6（Arf6）是一种小GTP酶，可促进CME所需的肌动蛋白组装。在其缺失的情况下，生长因子信号传导大大减弱，这已被证明可改善患病脉管系统中的病理信号输入。然而，尚不清楚与Arf6缺失相关的对血管生成行为的旁观者效应是否存在。我们的目标是分析Arf6在血管生成内皮细胞中的功能，重点关注其在管腔形成中的作用以及与肌动蛋白和CME的关系。我们发现在二维培养中，Arf6定位于丝状肌动蛋白和CME位点。Arf6的缺失扭曲了顶基极性并降低了细胞总丝状肌动蛋白含量，这可能是其缺失时血管生成芽生过程中严重畸形发生的主要驱动因素。我们的研究结果表明，内皮Arf6是肌动蛋白调节和CME的有效介质。
