Introduction

The endothelial glycocalyx is susceptible to high concentration of glucose and sodium in the blood. These challenges often involve an increase in osmotic pressure which may independently alters the glycocalyx components. The glycocalyx anchors on the cell membrane via core proteins that link with the actin cytoskeleton. This study aims to investigate the role of actomyosin in the osmoregulation of syndecan-1, a core protein that bears abundant sugar chains of the glycocalyx.

Methods

Human umbilical vein endothelial cells were incubated with mannitol-based hyperosmotic medium up to 2 h. The surface expression of syndecan-1 and the actin cytoskeleton were analysed by confocal microscopy, either without or with cytoskeletal manipulation.

Results

Syndecan-1 expression was compromised when hyperosmotic challenge was prolonged for 2 h, with the normalised intensity substantially dropped to 65.78 ± 2.07% at +200 mOsm. The reduction is associated with a sustained actin hyper-polymerisation, including significant increases in cortex coverage and cytoskeletal tension. Disassembling the cortex by cytochalasin D restores syndecan-1 in hyperosmosis. Inhibition of ROCK, rather than MLCK and myosin II ATPase activity, prevents the reduction of syndecan-1.

Conclusion

We have demonstrated that prolonged hyperosmotic stress disrupts the integrity of syndecan-1 through an aberrant cortex polymerisation. Our results provide new evidence in the interplay between the glycocalyx and the actin. It helps us better interpret the regulation of the glycocalyx, moving towards a goal of protecting and restoring the glycocalyx under healthy and diseased conditions.

中文翻译：

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肌动球蛋白在高渗中syndecan-1调控中的作用

介绍

内皮糖萼易受血液中高浓度葡萄糖和钠的影响。这些挑战通常涉及渗透压的增加，这可能会独立地改变糖萼成分。糖萼通过与肌动蛋白细胞骨架相连的核心蛋白锚定在细胞膜上。本研究旨在研究肌动球蛋白在 syndecan-1 渗透调节中的作用，syndecan-1 是一种核心蛋白，具有丰富的糖萼糖链。

方法

人脐静脉内皮细胞与基于甘露醇的高渗培养基一起培养长达 2 小时。在没有或有细胞骨架操作的情况下，通过共聚焦显微镜分析 syndecan-1 和肌动蛋白细胞骨架的表面表达。

结果

当高渗挑战延长 2 小时时，Syndecan-1 表达受到影响，标准化强度在 +200 mOsm 时大幅下降至 65.78 ± 2.07%。这种减少与持续的肌动蛋白高聚合有关，包括皮层覆盖率和细胞骨架张力的显着增加。通过细胞松弛素 D 分解皮质可恢复高渗中的 Syndecan-1。ROCK 的抑制，而不是 MLCK 和肌球蛋白 II ATPase 的活性，可以防止 syndecan-1 的减少。

结论

我们已经证明，长时间的高渗压力会通过异常的皮质聚合破坏 syndecan-1 的完整性。我们的结果为糖萼和肌动蛋白之间的相互作用提供了新的证据。它帮助我们更好地解释糖萼的调节，朝着在健康和患病条件下保护和恢复糖萼的目标迈进。