Syndecan Shedding in Vascular Lesion Formation

描述(由申请人提供)： 我们推测，氧化脂质以及局部机械应力调节Syndecan-1和-4的表达和脱落，作为一种初始的适应性反应，最终有助于产生持续的促炎和生长刺激环境，从而导致血管病变的形成。特别是，我们推测，响应这些促炎刺激而释放的突触蛋白将优先结合并有效地隔离与血管病变形成相关的趋化因子和蛋白。具体地说，我们计划(1)确定动脉壁力学和氧化脂质作为独立和交互因素调节Syndecan表达和脱落的能力。用免疫组织化学和原位杂交技术研究高血压ApoE缺陷小鼠Syndecan-1和Syndecan-4的表达。此外，还将进行相关的体外研究，以确定循环机械应力和氧化脂质作为单独和相互作用的因素在血管平滑肌细胞和外膜成纤维细胞中促进Syndecan表达和脱落的能力。(2)表征机械应激和氧化脂质激活的信号转导通路在调节Syndecan表达和脱落方面的趋同。氧化还原敏感和不敏感的MAPK信号通路对机械应力和氧化脂质的反应在多大程度上共同调节Syndecan的脱落和表达将被确定。此外，还将研究独特的途径不同地调节Syndecan表达和脱落的可能性，并确定在血管间充质细胞中，金属蛋白酶作为加速Syndecan脱落的主要介质的作用。(3)确定脱胶与部分促动脉粥样硬化趋化因子和蛋白水解酶之间的分子结合作用。我们将研究特定趋化因子(RANTES，MCP-1)和蛋白水解酶(MMP2，MMP9)与Syndecan相关的硫酸乙酰肝素链在氧化脂质和/或机械应力作用下脱落的相对结合亲和力，并确定复杂蛋白质对降解的敏感性。这些数据将有助于后续的研究，旨在评估肝素和硫酸软骨素的药理抑制剂的能力，以及在体外和体内限制促炎或蛋白分解活性固相梯度的形成的综合方案。

DESCRIPTION (provided by applicant): We postulate that oxidized lipids, as well as local mechanical stress regulate the expression and shedding of syndecan-1 and -4 as an initial adaptive response that ultimately contributes to the generation of a sustained proinflammatory, growth-stimulating environment that leads to vascular lesion formation. In particular, we speculate that syndecans shed in response to these pro-inflammatory stimuli will preferentially bind and effectively sequester chemokines and proteases relevant to vascular lesion formation. Specifically, we plan to (1) Determine the capacity of arterial wall mechanics and oxidized lipids, both as isolated and interactive factors, to modulate syndecan expression and shedding. The expression of syndecan- 1 and -4 will be characterized in hypertensive ApoE deficient mice using immunohistochemical and in situ hybridization techniques. Moreover, correlative in vitro studies will be performed to determine the capacity of cyclic mechanical stress and oxidized lipids, both as isolated and interactive factors, to potentiate syndecan expression and shedding in vascular smooth muscle cells and periadventitial fibroblasts. (2) Characterize the signal transduction pathways activated by mechanical stress and oxidized lipids that converge in regulating syndecan expression and shedding. The extents to which redox-sensitive and insensitive MAP kinase signaling pathways initiated in response to mechanical stress and oxidized lipids converge in regulating syndecan shedding and expression will be determined. Furthermore, the potential that unique pathways differentially regulate syndecan expression and shedding will be investigated and the role of metalloproteinases as primary mediators of accelerated syndecan shedding in vascular mesenchymal cells will be defined. (3) Define the molecular binding interactions between shed syndecans and selected proatherogenic chemokines and proteases. The relative binding affinities of selected chemokines (RANTES, MCP-1) and proteases (MMP-2, MMP-9) to syndecan associated heparan sulfate chains shed in response to oxidized lipids and/or mechanical stress will be characterized and the susceptibility of the complexed protein to degradation will be defined. This data will facilitate subsequent studies directed at assessing the capacity of pharmacological inhibitors of heparan and chondroitin sulfate, as well as syndecan shedding to limit the formation of pro-inflammatory or proteolytically active solid phase gradients in vitro and in vivo.