Syndecan-1 and the Arterial Response to Injury

说明书(申请人提供)：Syndecans(Syndecans-1、-2、-3和-4)是跨膜肝素和硫酸软骨素蛋白多糖(HSPGs)，由动脉平滑肌细胞(SMCs)表达，在受损的动脉中调节，结合各种生长因子和细胞外基质(ECM)的组成部分，是细胞-生长因子、细胞-细胞和细胞-ECM相互作用的重要调节因子。虽然已知硫酸肝素糖胺聚糖和肝素通过抑制SMC的迁移和增殖以及改变SMC ECM的产生来抑制损伤诱导的内膜增厚，但Syndecans在SMC生长和对动脉损伤的反应中的作用尚未确定。我们最近发现Syndecan-1基因缺失的小鼠损伤的颈动脉内膜增厚和中膜增殖明显增加。此外，这些小鼠培养的动脉SMCs在PDGF-BB、血清、EGF、FGF2和凝血酶的作用下，表达更高水平的PDGF-B mRNA，并比野生型小鼠的SMC迁移和增殖更多。PDGF-B链和PDGFR-β的siRNAs分别抑制凝血酶、PDGF-BB和血清诱导的SMC增殖。这些发现向我们证明Syndecan-1是动脉SMC生长的负调节因子。这项建议的主要目标是确定Syndecan-1转录是如何调控的，以及Syndecan-1如何控制PDGF-B的诱导以响应生长因子。其具体目的是：1.明确Syndecan-1在体外和体内的调控机制；2.明确Syndecan-1抑制凝血酶介导的PDGF-B链诱导的机制；3.在结构-功能研究中确定Syndecan-1的胞外结构域、胞浆结构域或两者都是Syndecan-1抑制PDGF-B诱导和细胞生长所必需的。拟议的研究将提供有关syndecan-1的新见解，这将形成防止再狭窄的药理学发展的基础，再狭窄是一个影响大量接受冠状动脉支架血管成形术的患者的问题。 与公共健康相关：拟议的研究应提供有关syndecan-1的新见解，syndecan-1是一种由平滑肌细胞表达的分子，可抑制动脉损伤后内膜增厚的形成。这些观察结果将为开发预防再狭窄的药理学奠定基础，再狭窄是一个影响大量接受冠状动脉支架血管成形术的患者的问题。

DESCRIPTION (provided by applicant): Syndecans (syndecans-1, -2, -3, and -4) are transmembrane heparan and chondroitin sulfate proteoglycans (HSPGs), which are expressed by arterial smooth muscle cells (SMCs), are regulated in injured arteries, bind various growth factors and components of the extracellular matrix (ECM), and are important regulators of cell-growth factor, cell-cell, and cell-ECM interactions. While it is known that heparan sulfate glycosaminoglycans and heparin suppress injury-induced intimal thickening by inhibiting SMC migration and proliferation and by altering SMC ECM production, the role of syndecans in SMC growth and the response to arterial injury has not been defined. We have recently found that intimal thickening and medial proliferation are markedly increased in the injured carotid arteries of syndecan-1 null mice. In addition, cultured arterial SMCs from these mice express higher levels of PDGF-B mRNA and migrate and proliferate more than SMCs from wild-type mice in response to PDGF-BB, serum, EGF, FGF2, and thrombin. siRNAs for PDGF-B chain and PDGFR-beta knock down their respective targets and suppress thrombin-, PDGF-BB-, and serum-induced SMC proliferation. These findings demonstrate to us that syndecan-1 is a negative regulator of arterial SMC growth. The major goal of this proposal is to determine how syndecan-1 transcription is regulated and how syndecan-1 then controls PDGF-B induction in response to growth factors. The specific aims are: 1. To define the mechanism of syndecan-1 regulation in vitro and in vivo; 2. To define the mechanisms by which syndecan-1 inhibits thrombin-mediated induction of PDGF-B chain; and 3. To determine in structure-function studies whether the syndecan-1 ectodomain, the cytoplasmic domain, or both are required for syndecan-1 inhibition of PDGF-B induction and cell growth. The proposed studies should provide novel insights regarding syndecan-1, which will then form the basis for the development of pharmacology to prevent restenosis, a problem that affects large numbers of patients undergoing coronary stent angioplasty. PUBLIC HEALTH RELEVANCE: The proposed studies should provide novel insights regarding syndecan-1, a molecule expressed by smooth muscle cells that suppresses the formation of intimal thickening after arterial injury. These observations will then form the basis for the development of pharmacology to prevent restenosis, a problem that affects large numbers of patients undergoing coronary stent angioplasty.