PROTEOGLYCANS, GLYCOSAMINOGLYCANS AND ATHEROSCLEROSIS

摘要：以往的研究表明，在动脉粥样硬化和再狭窄的早期病变中，主要的血管间质硫酸软骨素蛋白多糖(CSPG)和与其相互作用的糖胺聚糖透明质酸(HA)在细胞外基质(ECM)中积聚。我们还发现，这两个分子的合成受到特定生长因子和细胞因子的高度调控，并在动脉平滑肌细胞(ASMC)被刺激迁移和增殖时受到调节。通过抑制泛西肯和透明质酸与细胞表面受体的相互作用，可以阻止血管内皮细胞的增殖和迁移。多种细菌在ECM中堆积的一个后果是捕获和保留脂蛋白。我们已经证明了Verscan与含有apoB和apoE的脂蛋白相互作用，并且这种相互作用被影响硫酸软骨素链生物合成的因素所增强。这些观察结果使我们继续探索细胞外基质中的Verscan/HA复合体在调节ASMC表型和脂蛋白在血管壁上滞留方面的重要性。我们假设VERSICAN/HA合成过程中的修饰对于ASMC的增殖和迁移是必需的，并且这些修饰影响ASMC的其他特性，例如在动脉粥样硬化形成的不同阶段重塑ECM的能力。我们进一步推测，维西康在ECM内的积聚是脂蛋白在细胞外积聚的部分原因。我们建议从四个方面来检验这些假说。第一个目标将解决关于Verscan和Verscan异构体表达在ASMC表型和基质重塑调节中的作用的问题。在这项工作中，我们将表达包含多种结构域的通西卡异构体和微型基因，并检测其对细胞增殖、迁移和基质蛋白沉积的影响。第二个目标包括实验，旨在检测ASMC中HA合成酶的表达，以及HA作为基质的细胞外成分和新发现的细胞内分子在ASMC增殖、迁移和ECM重塑中的作用。第三个目的是扩展我们关于脂蛋白与多种多样的硫酸软骨素侧链相互作用的研究。我们建议确定负责ApoB和ApoE-含脂蛋白与泛西康结合的特定寡糖序列，并确定引起硫酸软骨素链结构变化的因素，这些改变导致万西康与脂蛋白具有不同的亲和力。在第四个目标中，我们将使用新的试剂来检测在自然发生的动脉粥样硬化病变中Verscan变体和蛋白水解性裂解产物的存在，通过细胞介导的基因转移方法在损伤的大鼠颈动脉内膜模型中研究Verscan变体和HA合成酶的表达变化对病变进展的影响，并在脂肪喂养的转基因小鼠模型中使用定向过表达的Verscan变体来检测Verscan表达在体内血管病变中脂蛋白积累的作用。VERSICAN和HA代谢的操作应该影响动脉粥样硬化病变的进展和/或消退。

Abstract: Previous work indicates the versican, the major vascular interstitial chondroitin sulfate proteoglycan (CSPG), and the glycosaminoglycan, hyaluronan (HA), which interacts with versican, accumulate in the extracellular matrix (ECM) in early atherosclerotic and restenotic lesions. We have also shown that the synthesis of these two molecules is highly regulated by specific growth factors and cytokines and is modulated when arterial smooth muscle cells (ASMC) are stimulated to migrate and proliferate. Inhibition of the interaction of versican and HA with receptors at the cell surface blocks ASMC proliferation and migration. One consequence of versican accumulation in the ECM is the trapping and retention of lipoproteins. We have shown that versican interacts with apoB and apoE-containing lipoproteins and this interaction is enhanced by factors that influence chondroitin sulfate chain biosynthesis. These observations have led us to continue to explore the importance of versican/HA complexes in the ECM in the regulation of ASMC phenotype, and in the retention of lipoproteins in the vascular wall. We hypothesize that modifications in versican/HA synthesis are required for ASMC proliferation and migration, and that these modifications influence other properties of ASMC, such as the ability to remodel the ECM during different phases of atherogenesis. We further postulate that the accumulation of versican within the ECM is partly responsible for the extracellular accumulation of lipoproteins. We propose to examine these hypotheses in four aims. The first aim will address questions concerning the role of versican and versican isoform expression in the regulation of ASMC phenotype and matrix remodeling. In this work we will express versican isoforms and mini-genes that contain various domains of versican, and examine the effect on cell proliferation, migration and matrix protein deposition. The second aim includes experiments designed to examine the expression of HA synthases by ASMC, and the role of HA, both as an extracellular component of the matrix and as a newly discovered intracellular molecule, in ASMC proliferation, migration and ECM remodeling. The third aim is designed to extend our studies concerning the interaction of lipoproteins with versican chondroitin sulfate side chains. We propose to determine the specific oligosaccharide sequences that are responsible for the binding of ApoB and ApoE-contain lipoproteins to versican, and determine factors that induce changes in chondroitin sulfate chain structure that give rise to versican forms with differing affinities for lipoproteins. In the fourth aim, we will use new reagents to examine the presence of versican variants and proteolytic cleavage products in naturally-occurring atherosclerotic lesions, investigate the effect of altered expression of versican variants and HA synthases on lesion progression by a cell-mediated gene transfer approach in the injured rat carotid neointimal model, and use targeted over-expression of versican variants in a fat-fed transgenic mouse model to examine the role of versican expression on the accumulation of lipoproteins in vascular lesions in vivo. Manipulation of versican and HA metabolism should influence the progression and/or regression of atherosclerotic lesion development.