VASCULAR RECEPTORS FOR PLATELET-DERIVED GROWTH FACTOR

动脉粥样硬化是一个复杂的过程， 血管平滑肌细胞和随之而来的血管狭窄 腔。 动脉狭窄也发生在临床血管成形术后 手术，可能是对血管损伤的反应。 血小板衍生 生长因子（PDGF）可能参与刺激平滑肌 在这两种临床环境中的细胞增殖。 动物模型 饮食引起的动脉粥样硬化或血管球囊导管损伤 可以复制人类疾病中的血管病变。 但它 很难证明PDGF是增殖所必需的， 体内平滑肌细胞。 该提案的主要目标是发展 阻断体内PDGF作用的新方法， 因子可以在动脉粥样硬化形成的动物模型中测试。 这些方法 将基于对PDGF分子生物学的理解， 受体的 三种类型的蛋白质-蛋白质相互作用最近被 显示为PDGF受体信号转导所需：配体- 受体结合、受体-受体二聚化和受体相互作用 将产生三种类型的受体拮抗剂：1）可溶性 由胞外配体结合部分组成的拮抗剂 受体的区域将用于防止PDGF与 其细胞受体; 2）形成失活的突变PDGF受体 具有野生型受体的异二聚体将在分离的细胞中表达 并在体内的血管中，从而阻断 内源性受体; 3）将使用受体的胞质部分 破坏受体与关键信号分子的相互作用。 拮抗剂将使用一系列方法进行测试， 转基因动物的体外试验。 该提案代表了 专注于血管疾病，并建立在该赠款资助的工作基础上， 过去的七年 血小板源生长因子受体的纯化， 受体cDNA，抗受体抗体的产生，受体的研究 二聚化，信号转导机制的发现和产生 受体突变体的研究使得设计实验成为可能， 提议 该结果应为研究提供新的方法 PDGF在血管疾病中的作用，应该有助于设计新的治疗方法， 阻断生长因子在体内作用的策略。

Atherosclerosis is a complex process that involves the proliferation of vascular smooth muscle cells and the consequent narrowing of the vascular lumen. Stenosis of arteries also occurs after clinical angioplasty procedures, probably as a response to vascular injury. Platelet-derived growth factor (PDGF) is likely to be involved in stimulating smooth muscle cell proliferation in both of these clinical settings. Animal models of diet-induced atherosclerosis or balloon catheter injury of blood vessels can reproduce the vascular lesions seen in human disease. However it has been difficult to prove that PDGF is required for the proliferation of smooth muscle cells in vivo. The main goal of this proposal is to develop novel approaches to block PDGF action in vivo so that the role of this factor can be tested in animal models of atherogenesis. These approaches will be based on an understanding of the molecular biology of the PDGF receptor. Three types of protein-protein interactions have recently been shown to be required for signal transduction by PDGF receptors: ligand- receptor binding, receptor-receptor dimerization and receptor interactions three types of receptor antagonists will be generated: 1) Soluble antagonists consisting of portions of the extracellular ligand-binding region of the receptor will be used to prevent the interaction of PDGF with its cellular receptor; 2) Mutant PDGF receptors that form inactive heterodimers with wild type receptors will be expressed in isolated cells and in blood vessels in vivo and will thereby block the function of endogenous receptors; 3) Cytoplasmic portions of the receptor will be used to disrupt the interactions of receptors with key signalling molecules. The antagonists will be tested using a spectrum of methods from well- defined in vitro assays to transgenic animals. This proposal represents a focus on vascular disease and builds on work funded by this grant during the last seven years. The purification of PDGF receptors, cloning of receptor cDNA's, generation of antireceptor antibodies, studies of receptor dimerization, discoveries of signal transducing mechanisms and generation of receptor mutants have made it possible to design the experiments in this proposal. The results should provide new approaches for the study of the role of PDGF in vascular disease and should help devise new therapeutic strategies for blocking the actions of growth factors in vivo.