Molecular Dissection of IGF2R Growth Suppressor Activity

说明书(由申请人提供)：通过其许多配体结合功能， 胰岛素样生长因子Il/甘露糖6-磷酸受体(IGF2R)是 负责转运含甘露糖-6-磷酸(Man-6-P)的溶酶体 酶到其适当的细胞内目的地，用于中介摄取 以及随后有丝分裂原胰岛素样生长因子11的降解 (IGF-II)，并促进生长抑制因子的激活，转化 生长因子-b(TGF-b)。这些活动中的每一个都与 IGF2R作为肿瘤抑制因子的建议作用，但问题是 IGF2R的配体结合功能对细胞生长起作用 抑制者的活动尚未得到直接解决。该项目将测试 假设IGF2R的生长抑制活性依赖于 其IGF-II和Man-6-F结合功能的有效运行，通过 具体目标如下：1)衡量以下因素对增长的抑制作用 野生型IGF2R与受体在Man-6-P与IGF-II结合中的突变 功能。野生型IGF2R基因导入的IGF2R缺陷细胞系 IGF-II或Man-6-P结合缺陷的表达载体或IGF2R突变体 将分析与载体转染相关的配体的增殖情况。 控制。我们的预期是，野生型IGF2R表达增加将 抑制细胞生长，而突变体将表现出这种损伤 抑制生长的活动。2)确定癌症相关疾病的影响 M6P/IGF2R错义或截短突变对生长抑制活性的影响 IGF2R。我们预计错义突变将在 IGF2R功能和截断突变体可能具有新的显性-负性 效果。3)评估受体对生长抑制的作用 依赖IGF2R的受体前和受体后结合事件的活性 二聚化，即发展高亲和力的配体结合和增强 内部化。这些研究将有助于了解受体的 肿瘤抑制功能，并允许合理设计利用 IGF2R在肿瘤防治中的应用

DESCRIPTION (provided by applicant): Through its many ligand-binding functions, the insulin-like growth factor Il/mannose 6-phosphate receptor (IGF2R) is responsible for transporting mannose-6-phosphate (Man-6-P)-bearing lysosomal enzymes to their appropriate intracellular destination, for mediating uptake and subsequent degradation of the mitogen, insulin-like growth factor 11 (IGF-II), and for facilitating activation of the growth inhibitor, transforming growth factor-b (TGF-b). Each of these activities is consistent with the proposed role of the IGF2R as a tumor suppressor, yet the question of which ligand-binding functions of the IGF2R are responsible for the cell-growth suppressor activity have not been directly addressed. This project will test the hypothesis that the IGF2R's growth suppressor activity depends on the efficient operation of both its IGF-II and Man-6-F binding functions, by the following specific aims: 1) To measure the growth-suppressive effects of wild-type IGF2R vs. receptors mutated in the Man-6-P vs. IGF-II binding functions. IGF2R-deficient cell lines transfected with wild-type IGF2R cDNA expression constructs or IGF2R mutants defective in binding IGF-II or Man-6-P ligands will be analyzed for proliferation relative to vector-transfected controls. Our expectation is that increased wild-type IGF2R expression will inhibit cell growth, and that the mutants will show impairment of this growth-suppressive activity. 2) To determine the effects of cancer-associated M6P/IGF2R missense or truncation mutations on the growth-suppressive activity of the IGF2R. We expect that missense mutations will exhibit reductions in IGF2R function and that truncation mutants may have novel dominant-negative effects. 3) To assess the contribution to the receptor's growth-suppressive activity of pre- and post-receptor binding events that depend on IGF2R dimerization, i.e. development of high-affinity ligand binding and enhanced internalization. These studies will contribute to understanding the receptor's tumor suppressor function and permit rational design of strategies that exploit the IGF2R in cancer prevention and therapy.