Regulation mechanism of tissue remodeling by gloycosylation change-Functional modulation of extracellular matrix molecule, vitronectin, by its glycosylation change

Vitronectin(VN)是一种存在于细胞外基质和血浆中的多功能糖蛋白，在细胞黏附、细胞运动和基质重塑中发挥作用。其中一些结合活性受到VN糖基化变化的影响，而胶原结合活性在肝部分切除后肝再生过程中VN糖基化减少而增强。本研究探讨了Vitronectin的糖基化活化机制及其生物学意义，并通过分析不离心法研究了糖基化对VN多聚化的影响，以阐明多糖对VN生物活性的调控机制。结合胶原的最适pH为4.5时的沉降速度分析表明，VN的多聚化比在pH 7.5时更显著。神经氨酸酶处理的VN形成的多聚体大于未处理的VN。经N-聚糖酶处理后，VN多聚体的大小逐渐增大。…通过沉淀平衡分析，考察了VN多聚体在不同浓度的盐酸胍溶液中对变性剂的稳定性。神经氨酸酶处理的VN或N-葡聚糖酶处理的VN在盐酸胍浓度下仍以多聚体形式存在，在该浓度下对照VN解离。转化为单体，从而增强了脱糖基化VNS的多聚体稳定性。这些结果表明，去糖基化的VN增加了多聚体的大小和稳定性，最终通过多价效应增强了胶原结合活性。另一方面，肝硬化血浆(LC-VN)中VN的变化表明唾液酸化增加。LCVN与I型胶原结合减少。尿素治疗前后血浆的胶原结合研究表明，肝硬变患者血浆中VN的活性形式增加。提示LC-VN的糖基化改变和肝硬变血浆中活性VN的增加可能参与了VN的基质掺入和随后的修复或重塑过程。较少

Vitronectin (VN), a multifunctional glycoprotein present in the extracellular matrix and plasma, plays a role in cell adhesion, cellular motility and matrix remodeling. Some of these binding activities are affected by changes in glycosylation of VN and collagen-binding activity is enhanced by decreased glycosylation of VN during liver regeneration after a partial hepatectomy. In this study, the activating mechanism of vitronectin by its glycosylation and biological significance of it was studied.The effect of glycosylation on multimerization of VN was studied by analytical untracentrifugation to elucidate the modulation mechanism of the biological activity by glycans. Sedimentation velocity analysis at pH 4.5, an optimum pH for collagen binding, indicated that multimerization of VN was more remarkable than that at pH 7.5. Neuraminidase-treated VN formed a multimer larger than that of VN incubated without the enzyme. N-glycanase treatment gradually increased the size of the VN multimer. … More The stability of VN multimer against the denaturing agent was measured by sedimentation equilibrium analyzes at various concentrations of guanidine-HCl. The neuraminidase-treated or N-glycanase-treated VN remained in a multimer form at a guanidine-HCl concentration in which control VN dissociate*! Into monomers, enhancing thus the multimer stability of deglycosylated VNs. These results suggest that deglycosylated VN increased the size and stability of the multimer to eventually enhance the collagen binding activity by multivalent effect.On the other hand, changes of VN in cirrhotic plasma (LC-VN) indicated that sialylation was elevated. LCVN to exhibit decreased binding to type I collagen. Collagen-binding studies of plasma before and after urea-treatment indicated that the active form of VN increased in cirrhotic plasma. These changes indicate the glycosylation changes of LC-VN and the increase of active VN in cirrhotic plasma may contribute to the matrix incorporation of VN and subsequent repair or remodeling processes. Less