Syndecan-1 and the Arterial Response to Injury

描述（由申请人提供）：Syndecans （Syndecans -1、-2、-3和-4）是由动脉平滑肌细胞（SMCs）表达的跨膜肝素和硫酸软骨素蛋白聚糖（HSPGs），在受损动脉中受到调节，结合多种生长因子和细胞外基质（ECM）成分，是细胞生长因子、细胞间和细胞外基质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明确。我们最近发现，在syndecan-1缺失小鼠的颈动脉损伤中，内膜增厚和内侧增生明显增加。此外，在PDGF-BB、血清、EGF、FGF2和凝血酶的作用下，来自这些小鼠的培养动脉SMCs表达更高水平的PDGF-B mRNA，并且比来自野生型小鼠的SMCs迁移和增殖更多。PDGF-B链和pdgfr - β的sirna敲低各自的靶标，抑制凝血酶-、PDGF-BB-和血清诱导的SMC增殖。这些发现表明syndecan-1是动脉SMC生长的负调节因子。本提案的主要目标是确定syndecan-1转录是如何被调节的，以及syndecan-1如何在响应生长因子时控制PDGF-B的诱导。具体目标是：1。明确syndecan-1的体内外调控机制；2. 明确syndecan-1抑制凝血酶介导的PDGF-B链诱导的机制；和3。在结构-功能研究中确定syndecan-1抑制PDGF-B诱导和细胞生长是否需要syndecan-1外结构域、细胞质结构域或两者都需要。拟议的研究应提供关于syndecan-1的新见解，这将为预防再狭窄的药理学发展奠定基础，再狭窄是影响大量接受冠状动脉支架成形术患者的问题。

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.