Ligand-dependent and -independent actions of insulin-like growth factor binding proteins in fish

鱼中胰岛素样生长因子结合蛋白的配体依赖性和非依赖性作用

• 批准号: 0543018
• 负责人: Cunming Duan
• 金额: $ 56万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-02-01 至 2011-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0543018&HistoricalAwards=false
• 关键词: Ligand; dependent; independent; actions; insulin

Insulin-like growth factors (IGFs) are a family of peptide growth factors/hormones that are essential for normal animal growth and development. Recent studies suggest that the availability and bioactivity of IGFs are regulated by several specific, high-affinity IGF-binding proteins (IGFBPs). IGFBPs belong to a conserved gene family of proteins that bind to IGFs in extracellular environments. Since the binding affinities of IGFBPs for IGFs are equal to or even greater than those of the IGF receptors, they can control the amount of IGFs presented to their cell surface receptors and may play key roles in determining the biological activities of the IGF signaling pathway. There is also in vitro evidence that some IGFBPs have intrinsic biological activities that are IGF-independent. This project is designed to test the hypothesis that different members of the IGFBP family are expressed in spatially and temporally restricted fashions and they each play distinct roles in regulating tissue growth and differentiation through IGF-dependent and -independent mechanisms. The current project has 3 aims. In the first aim, the mechanistic basis of IGFBP-3 action in regulating head skeleton and inner ear growth and differentiation will be investigated with special focus on the role of ligand binding and nuclear targeting. For this, native and mutant IGFBP-3 will be expressed in IGFBP-3 knocked down embryos for in vivo mechanistic studies. Aim 2 seeks to determine the structure of zebrafish IGFBP-4, map its spatial and temporal expression pattern, and investigate its physiological functions in vivo. In Aim 3, the mode of IGFBP-4 action and the possible role of proteolysis in controlling local IGFBP-4 action will be studied in vitro and in vivo. Aim 4 seeks to determine zebrafish IGFBP-6 structure, developmental expression, physiological functions in vivo, and elucidate the molecular mechanisms underlying its actions. The completion of the proposed studies will provide novel and important insights into the functions of IGFBPs and the mechanistic basis underlying their biological actions. For the first time, the functional significance of ligand-independent actions, nuclear localization, and proteolysis of an IGFBP will be examined in vivo. An understanding of the underlying mechanisms of growth regulation in fish will undoubtedly contribute to vertebrate growth physiology in general. A better understanding of the underlying mechanisms of growth regulation in zebrafish should help to understand human growth physiology and may have applications in aquaculture for efficient production of animal protein as well. This research project is also of importance for understanding the structural and functional evolution of the IGFBP gene family and will expand research infrastructure in Michigan and increase research and training opportunities for undergraduate and graduate students.

胰岛素样生长因子 (IGF) 是肽生长因子/激素家族，对于正常动物生长和发育至关重要。最近的研究表明，IGF 的可用性和生物活性受几种特异性、高亲和力 IGF 结合蛋白 (IGFBP) 的调节。 IGFBP 属于保守的蛋白质基因家族，可在细胞外环境中与 IGF 结合。由于IGFBP与IGF的结合亲和力等于甚至大于IGF受体，因此它们可以控制呈递给其细胞表面受体的IGF的量，并且可能在确定IGF信号通路的生物活性中发挥关键作用。还有体外证据表明，一些 IGFBP 具有不依赖于 IGF 的内在生物活性。该项目旨在检验以下假设：IGFBP 家族的不同成员以空间和时间受限的方式表达，并且它们各自通过 IGF 依赖和独立机制在调节组织生长和分化中发挥不同的作用。当前项目有 3 个目标。第一个目标是研究 IGFBP-3 在调节头部骨骼和内耳生长和分化中作用的机制基础，特别关注配体结合和核靶向的作用。为此，天然和突变的 IGFBP-3 将在 IGFBP-3 敲低的胚胎中表达，以进行体内机制研究。目标 2 旨在确定斑马鱼 IGFBP-4 的结构，绘制其时空表达模式，并研究其体内生理功能。在目标 3 中，将在体外和体内研究 IGFBP-4 的作用模式以及蛋白水解在控制局部 IGFBP-4 作用中的可能作用。目标 4 旨在确定斑马鱼 IGFBP-6 的结构、发育表达、体内生理功能，并阐明其作用的分子机制。拟议研究的完成将为 IGFBP 的功能及其生物作用的机制基础提供新颖且重要的见解。首次在体内检查 IGFBP 的配体独立作用、核定位和蛋白水解的功能意义。了解鱼类生长调节的基本机制无疑将有助于脊椎动物的整体生长生理学。更好地了解斑马鱼生长调节的基本机制应有助于了解人类生长生理学，并可能在水产养殖中有效生产动物蛋白方面有所应用。该研究项目对于理解 IGFBP 基因家族的结构和功能进化也具有重要意义，并将扩大密歇根州的研究基础设施，并增加本科生和研究生的研究和培训机会。