IGFBP5 AND INTEGRINS AND CONTROLLING IGF1 ACTIONS

IGFBP5 和整合素以及控制 IGF1 的作用

• 批准号: 2624015
• 负责人: DAVID Robert CLEMMONS
• 金额: $ 32.23万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 1980
• 资助国家: 美国
• 起止时间: 1980-08-01 至 2003-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2624015
• 关键词: atherosclerotic plaque; binding proteins; biological signal transduction; cell migration; extracellular matrix; growth factor receptors; insulinlike growth factor; integrins; laboratory rabbit; muscle cells; mutant; osteopontin; protease inhibitor; protein binding; protein kinase; proteolysis; receptor binding; smooth muscle; swine; thrombin; thrombospondins; tissue /cell culture; urokinase; vitronectin

The purpose of these studies is to analyze the molecular mechanisms by which ligand occupancy of intergrin receptors and high affinity binding proteins alter the capacity of insulin-like growth factor-I (IGF-I) to stimulate smooth muscle cell (SMC) replication and migration. SMC constitutively synthesize IGF-I and IGFBPs which have been shown to modulate IGF actions. They also contain the alphaVbeta3 integrin receptor and ligand occupancy of alphaVbeta3 alters the SMC response to IGF-I. These studies to determine the role of proteolysis of IGFBP-5 in altering the amount if IGF-I is exposed to receptors. A cDNA probe containing the protease sequence and a high affinity antiprotease antiserum will be used to determine the variable that increase its synthesis and/or activation from and inactive form. They will also be used to screen for the presence of protease or inhibitors and to determine if any of the SMC growth factors that function together with IGF-1 alter protease inhibitors synthesis. The functional consequences of altering protease activity on IGF-1 actions will be determined. The role of thrombin which cleaves IGFBP-5 at physiologic concentrations or in releasing it from extracellular matrix and in modifying IGF actions will be analyzed. Additional studies will focus on the role of IGFBP-5 binding to three specific ECM proteins, thrombospondin, vitronectin and osteopontin and how this alters their ability to interact with the alphaVbeta3 receptor. Fragments of IGFBP-5 that do not bind to IGF-I will be tested for their capacity to bind to these proteins and to alter alphaVbeta3 modulation of IGF-I actions. Mutants that have been prepared that have deficient ECM binding will be analyzed to determine if binding to any of these three proteins is reduced and if selective loss of binding altered pSMC responsiveness to IGF-I. Studies will determine the mechanism by which of ligand occupancy of alphaVbeta3 modifies IGF-I receptor kinase activity will be undertaken. Studies will initiated to determine if these two receptors co-localize in the focal adhesion complex (FAC) with other FAC proteins. Since alpha2beta1 ligand occupancy is a negative regulator of IGF action, we will determine if Type IV collagen binding to this receptor modifies activation of the IGF-1 receptor by alphaVbeta3. Blocking the UPAR receptor specifically inhibits IGF-1 stimulated migration. Studies will be undertaken to determine if PI-3 kinase is an important signaling element in this pathway. The results of these studies should help to define the molecular mechanisms by which IGF-I functions coordinately with ECM proteins and integrins to stimulate SMC migration and replication and may suggest novel strategies for interfering with these processes to alter the progression of atherosclerosis.

这些研究的目的是分析分子机制， 其中整合素受体的配体占有率和高亲和力结合 蛋白质改变胰岛素样生长因子-I（IGF-I）的能力， 刺激平滑肌细胞（SMC）复制和迁移。 SMC 组成型合成IGF-I和IGFBPs， 调节IGF的作用。 它们还含有α V β 3整联蛋白 α V β 3的受体和配体占据改变了SMC对 IGF-I。 这些研究旨在确定IGFBP-5的蛋白水解作用 如果IGF-I暴露于受体，则会改变IGF-I的量。 cDNA探针 含有蛋白酶序列和高亲和性抗蛋白酶 将使用抗血清来确定增加其 合成和/或活化。 他们还将 用于筛选蛋白酶或抑制剂的存在， 确定是否有任何SMC生长因子与 IGF-1改变蛋白酶抑制剂的合成。 功能性后果 将确定改变蛋白酶活性对IGF-1作用的影响。 的 凝血酶在生理浓度下切割IGFBP-5的作用，或 从细胞外基质中释放出来， 将被分析。 更多的研究将集中在IGFBP-5的作用 结合三种特异性ECM蛋白，血小板反应蛋白，玻连蛋白和 骨桥蛋白以及这如何改变它们与骨桥蛋白相互作用的能力。 α V β 3受体。不与IGF-I结合的IGFBP-5片段 将测试它们与这些蛋白质结合的能力， IGF-I作用的α V β 3调节。 已经被 将分析具有缺陷ECM结合的制备物以确定 如果与这三种蛋白质中的任何一种的结合减少， 结合的丧失改变了pSMC对IGF-I的反应性。研究将 确定α V β 3的配体占据的机制 改变IGF-I受体激酶活性。 研究 将启动以确定这两种受体是否共定位在 粘着斑复合物（FAC）与其他FAC蛋白。由于α 2 β 1 配体占有率是IGF作用的负调节因子，我们将 确定IV型胶原与该受体的结合是否会改变 通过α V β 3激活IGF-1受体。 阻止UPAR 受体特异性抑制IGF-1刺激的迁移。 研究 将进行，以确定PI-3激酶是否是一个重要的信号转导 这条路上的元素。 这些研究的结果应该有助于 确定IGF-I协同作用的分子机制 与ECM蛋白和整合素一起刺激SMC迁移， 复制，并可能提出新的策略，干扰这些 改变动脉粥样硬化进展的过程。