School of Life Science, Beijing Institute of Technology, No. 5 Zhongguancun South Street, Haidian District, Beijing 100081, China.
Int J Mol Sci. 2021 May 13;22(10):5165. doi: 10.3390/ijms22105165.
The blood-brain barrier (BBB) is critical to maintaining central nervous system (CNS) homeostasis. However, the effects of microgravity (MG) on the BBB remain unclear. This study aimed to investigate the influence of simulated MG (SMG) on the BBB and explore its potential mechanism using a proteomic approach. Rats were tail-suspended to simulate MG for 21 days. SMG could disrupt the BBB, including increased oxidative stress levels, proinflammatory cytokine levels, and permeability, damaged BBB ultrastructure, and downregulated tight junctions (TJs) and adherens junctions (AJs) protein expression in the rat brain. A total of 554 differentially expressed proteins (DEPs) induced by SMG were determined based on the label-free quantitative proteomic strategy. The bioinformatics analysis suggested that DEPs were mainly enriched in regulating the cell-cell junction and cell-extracellular matrix biological pathways. The inhibited Ras-related C3 botulinum toxin substrate 1 (Rac1)/Wiskott-Aldrich syndrome protein family verprolin-homologous protein 2 (Wave2)/actin-related protein 3 (Arp3) pathway and the decreased ratio of filamentous actin (F-actin) to globular actin contributed to BBB dysfunction induced by SMG. In the human brain microvascular endothelial cell (HBMECs), SMG increased the oxidative stress levels and proinflammatory cytokine levels, promoted apoptosis, and arrested the cell cycle phase. Expression of TJs and AJs proteins were downregulated and the distribution of F-actin was altered in SMG-treated HBMECs. The key role of the Rac1/Wave2/Arp3 pathway in BBB dysfunction was confirmed in HBMECs with a specific Rac1 agonist. This study demonstrated that SMG induced BBB dysfunction and revealed that Rac1/Wave2/Arp3 could be a potential signaling pathway responsible for BBB disruption under SMG. These results might shed a novel light on maintaining astronaut CNS homeostasis during space travel.
血脑屏障（BBB）对于维持中枢神经系统（CNS）内环境稳定至关重要。然而，微重力（MG）对 BBB 的影响尚不清楚。本研究旨在使用蛋白质组学方法研究模拟 MG（SMG）对 BBB 的影响及其潜在机制。通过尾部悬吊法使大鼠模拟 MG 21 天。SMG 可破坏 BBB，包括增加氧化应激水平、促炎细胞因子水平和通透性，损伤 BBB 超微结构，并下调大鼠脑内紧密连接（TJ）和黏附连接（AJ）蛋白表达。基于无标记定量蛋白质组学策略，确定了 554 种由 SMG 诱导的差异表达蛋白（DEPs）。生物信息学分析表明，DEPs 主要富集在调节细胞-细胞连接和细胞-细胞外基质生物途径。抑制 Ras 相关 C3 肉毒梭菌毒素底物 1（Rac1）/Wiskott-Aldrich 综合征蛋白家族 verprolin 同源蛋白 2（Wave2）/肌动蛋白相关蛋白 3（Arp3）通路和丝状肌动蛋白（F-actin）与球状肌动蛋白的比值降低，导致 SMG 诱导的 BBB 功能障碍。在人脑微血管内皮细胞（HBMECs）中，SMG 增加了氧化应激水平和促炎细胞因子水平，促进了细胞凋亡，并使细胞周期停滞在 G1 期。TJ 和 AJ 蛋白的表达下调，SMG 处理后的 HBMECs 中 F-actin 的分布发生改变。在 HBMECs 中，特异性 Rac1 激动剂证实了 Rac1/Wave2/Arp3 通路在 BBB 功能障碍中的关键作用。本研究表明，SMG 诱导 BBB 功能障碍，并揭示 Rac1/Wave2/Arp3 可能是 SMG 下 BBB 破坏的潜在信号通路。这些结果可能为宇航员在太空旅行期间维持中枢神经系统内环境稳定提供新的思路。
