Department of Biomedical Engineering, The City College of New York, New York;
Am J Physiol Heart Circ Physiol. 2013 Sep 15;305(6):H811-20. doi: 10.1152/ajpheart.00764.2012. Epub 2013 Jul 12.
The endothelial glycocalyx plays important roles in mechanotransduction. We recently investigated the distribution and interaction of glycocalyx components on statically cultured endothelial cells. In the present study, we further explored the unknown organization of the glycocalyx during early exposure (first 30 min) to shear stress and tested the hypothesis that proteoglycans with glycosaminoglycans, which are localized in different lipid microdomains, respond distinctly to shear stress. During the initial 30 min of exposure to shear stress, the very early responses of the glycocalyx and membrane rafts were detected using confocal microscopy. We observed that heparan sulfate (HS) and glypican-1 clustered in the cell junctions. In contrast, chondroitin sulfate (CS), bound albumin, and syndecan-1 did not move. The caveolae marker caveolin-1 did not move, indicating that caveolae are anchored sufficiently to resist shear stress during the 30 min of exposure. Shear stress induced significant changes in the distribution of ganglioside GM1 (a marker for membrane rafts labeled with cholera toxin B subunit). These data suggest that fluid shear stress induced the cell junctional clustering of lipid rafts with their anchored glypican-1 and associated HS. In contrast, the mobility of CS, transmembrane bound syndecan-1, and caveolae were constrained during exposure to shear stress. This study illuminates the role of changes in glycocalyx organization that underlie mechanisms of mechanotransduction.
内皮糖萼在力学转导中发挥重要作用。我们最近研究了糖萼成分在静态培养的内皮细胞上的分布和相互作用。在本研究中，我们进一步探索了在早期暴露（最初 30 分钟）于切应力下糖萼的未知组织，并且测试了这样一个假设，即具有糖胺聚糖的蛋白聚糖，其定位于不同的脂质微区中，对切应力有明显不同的反应。在暴露于切应力的最初 30 分钟内，使用共焦显微镜检测糖萼和质膜筏的早期反应。我们观察到肝素硫酸盐（HS）和糖蛋白聚糖-1在细胞连接处聚集。相比之下，软骨素硫酸盐（CS）、结合白蛋白和 syndecan-1 没有移动。质膜筏的标记物 caveolin-1 没有移动，表明 caveolae 在暴露于切应力的 30 分钟内被充分固定以抵抗切应力。切应力诱导神经节苷脂 GM1（用霍乱毒素 B 亚基标记的质膜筏的标记物）分布发生显著变化。这些数据表明，流体切应力诱导质膜筏与锚定的 glypican-1 和相关的 HS 在细胞连接处聚集。相比之下，CS、跨膜结合的 syndecan-1 和 caveolae 的流动性在暴露于切应力时受到限制。这项研究阐明了糖萼组织变化在力学转导机制中的作用。
