Department of Pharmacology, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA, 70112, USA.
Tulane Brain Institute, Tulane University, 200 Flower Hall, 6823 St. Charles Avenue, New Orleans, LA, 70118, USA.
Geroscience. 2024 Feb;46(1):395-415. doi: 10.1007/s11357-023-00988-y. Epub 2023 Oct 28.
We previously reported evidence that oxidative stress during aging leads to adverse protein profile changes of brain cortical microvessels (MVs: end arterioles, capillaries, and venules) that affect mRNA/protein stability, basement membrane integrity, and ATP synthesis capacity in mice. As an extension of our previous study, we also found that proteins which comprise the blood-brain barrier (BBB) and regulate mitochondrial quality control were also significantly decreased in the mice's cortical MVs with aging. Interestingly, the neuroinflammatory protein fibrinogen (Fgn) was increased in mice brain MVs, which corresponds with clinical reports indicating that the plasma Fgn concentration increased progressively with aging. In this study, protein-protein interaction network analysis indicated that high expression of Fgn is linked with downregulated expression of both BBB- and mitochondrial fission/fusion-related proteins in mice cortical MVs with aging. To investigate the mechanism of Fgn action, we observed that 2 mg/mL or higher concentration of human plasma Fgn changed cell morphology, induced cytotoxicity, and increased BBB permeability in primary human brain microvascular endothelial cells (HBMECs). The BBB tight junction proteins were significantly decreased with increasing concentration of human plasma Fgn in primary HBMECs. Similarly, the expression of phosphorylated dynamin-related protein 1 (pDRP1) and other mitochondrial fission/fusion-related proteins were also significantly reduced in Fgn-treated HBMECs. Interestingly, DRP1 knockdown by shRNA(h) resulted in the reduction of both BBB- and mitochondrial fission/fusion-related proteins in HBMECs. Our results suggest that elevated Fgn downregulates DRP1, leading to mitochondrial-dependent endothelial and BBB dysfunction in the brain microvasculature.
我们之前的研究报告表明，衰老过程中的氧化应激会导致大脑皮质微血管（MV：终末小动脉、毛细血管和小静脉）的不良蛋白谱变化，从而影响 mRNA/蛋白质稳定性、基底膜完整性和 ATP 合成能力。作为我们之前研究的延伸，我们还发现，随着年龄的增长，构成血脑屏障（BBB）并调节线粒体质量控制的蛋白质在小鼠大脑皮质 MV 中也显著减少。有趣的是，神经炎症蛋白纤维蛋白原（Fgn）在小鼠脑 MV 中增加，这与临床报告相吻合，表明血浆 Fgn 浓度随着衰老而逐渐增加。在这项研究中，蛋白质-蛋白质相互作用网络分析表明，Fgn 的高表达与衰老小鼠大脑皮质 MV 中 BBB 和线粒体分裂/融合相关蛋白的下调表达有关。为了研究 Fgn 的作用机制，我们观察到 2mg/ml 或更高浓度的人血浆 Fgn 改变了原代人脑微血管内皮细胞（HBMEC）的细胞形态，诱导细胞毒性，并增加了 BBB 的通透性。随着人血浆 Fgn 浓度的增加，BBB 紧密连接蛋白在原代 HBMEC 中显著减少。同样，在 Fgn 处理的 HBMEC 中，磷酸化动力相关蛋白 1（pDRP1）和其他线粒体分裂/融合相关蛋白的表达也显著降低。有趣的是，DRP1 的 shRNA(h) 敲低导致 HBMEC 中 BBB 和线粒体分裂/融合相关蛋白的减少。我们的结果表明，升高的 Fgn 下调 DRP1，导致大脑微血管内皮细胞和 BBB 功能障碍。
