CONTROL OF IGF-1 ACTIVITY BY INTERACTION WITH CELL ASSOCIATED BINDING PROTEINS

胰岛素样生长因子（IGF-I和IGF-II）对 局部生长过程以及细胞和组织分化的研究， 很好的。 严格控制表达的机制， IGF-I的活性必须存在，因为许多细胞类型产生和 对IGF-I的反应。 两种IGFs的许多作用都是由IGF-I介导的 受体，异四聚体酪氨酸特异性蛋白激酶 在结构上与胰岛素受体相关。 我的长期目标是 实验室一直在了解功能之间的相互作用 IGF-I及其细胞表面受体和结合蛋白。 我们以前的 研究已经阐明了IGF-I受体亚单位之间的相互作用， 这是高亲和力IGF-I结合和IGF-I- 刺激自磷酸化。 在本申请中， 可能控制IGF-I活性，特别是IGF-I与 细胞相关的IGF结合蛋白和IGF-I的生产作为两个 前蛋白可能需要通过其有限的蛋白水解来活化， E域，将进行调查。 提出了三个具体目标。 首先，IGF结合蛋白与细胞表面的相互作用 和/或细胞外基质。 我们 以前曾描述过一个身材矮小的孩子的成纤维细胞 (CSC)产生丰富的细胞相关IGF结合蛋白。 的 CSC成纤维细胞中相互作用的细胞分子将被定位， 纯化，并将其识别位点进行表征。 二是 IGFBP-3的寡糖单元的结构，主要的IGF结合 将分析血清和成纤维细胞中的蛋白质。 功能 糖基化对于IGFBP-3通过 细胞，用于其细胞缔合，和/或用于其稳定性， 将检测蛋白水解降解。 第三，生物 将测定人IGF-IA和IGF-IB的性质和活化。 与Peter Rotwein博士（项目#1）合作，我们表达了 杆状病毒系统中的IGF-IA。 IGF-IA和IGF-IB均将表达 并进行了大量的纯化，使我们能够比较它们的生物活性 与成熟的70个残基IGF-I，并阐明其翻译后 处理. 预计这些研究将导致更好的 了解控制正常人IGF-I活性的机制 增长

The importance of the insulin-like growth factors (IGF-I and IGF-II) on local growth processes and in cell and tissue differentiation is now well-establish. Mechanisms that tightly control the expression and activity of IGF-I must exist because numerous cell types produce and respond to IGF-I. Many actions of both IGFs are mediated by the IGF-I receptor, a heterotetrameric tyrosine-specific protein kinase structurally related to the insulin receptor. The long-term goal of my laboratory has been to understand the functional interactions between IGF-I and its cell surface receptor and binding proteins. Our previous studies have elucidated the interactions between IGF-I receptor subunits that are necessary for high-affinity IGF-I binding and for IGF-I- stimulated autophosphorylation. In this application, two mechanisms that may control IGF-I activity, specifically, the interaction of IGF-I with cell-associated IGF binding proteins and the production of IGF-I as two proproteins which may require activation by limited proteolysis of their E domains, will be investigated. Three specific aims are proposed. First, the interaction of IGF binding proteins with the cell surface and/or extracellular matrix in human fibroblasts will be defined. We have previously characterized fibroblasts from a child with short stature (CSC) that produce abundant cell-associated IGF binding proteins. The interacting cellular molecules in CSC fibroblasts will be localized and purified, and their recognition sites will be characterized. Second, the structures of the oligosaccharide units of IGFBP-3, the major IGF binding protein in serum and in fibroblasts, will be analyzed. The functional importance of glycosylation for the translocation of IGFBP-3 through the cell, for its cellular association, and/or for its stability to proteolytic degradation will be examined. Third, the biological properties and activation of human IGF-IA and IGF-IB will be determined. In collaboration with Dr. Peter Rotwein (Project #1), we have expressed IGF-IA in a baculovirus system. Both IGF-IA and IGF-IB will be expressed and purified in amounts that will allow us to compare their bioactivity with mature 70 residue IGF-I and to elucidate their post-translational processing. It is anticipated that these studies will lead to a better understanding of the mechanisms that control IGF-I activity in normal growth.