INTESTINAL ADAPTATION--ROLE OF HORMONES & GROWTH FACTORS

肠道适应——激素的作用

• 批准号: 6074823
• 负责人: PAULINE K LUND
• 金额: $ 3.61万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-01-01 至 1999-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6074823
• 关键词: binding proteins; cell differentiation; cell growth regulation; cell line; cell proliferation; gastrointestinal epithelium; genetically modified animals; growth factor; histogenesis; hormone regulation /control mechanism; insulinlike growth factor; intestinal mucosa; laboratory mouse; mixed tissue /cell culture; protein localization; small intestines; somatotropin

DESCRIPTION: This revised application focuses on the roles and mechanisms of Insulin-like growth factor (IGF-I) and IGF binding proteins (IGFBPs) in intestinal adaptation. Systemic growth hormone (GH) and IGF-I promote intestinal adaptation in an endocrine manner. IGF-I mediates many of the actions of GH in bowel. Clinical trials of GH and IGF-I as therapy for short bowel syndrome and other bowel diseases are in progress. Yet, there is virtually no direct information about the intracellular mechanisms of IGF-I action in bowel. Adaptive changes in growth of small bowel mucosa correlate with levels of locally expressed IGF-I indicating paracrine or autocrine effects of IGF-I in bowel. GH increases local expression of IGF-I within small bowel. The role of locally expressed IGF-I in adaptive growth of the small bowel mucosa is not defined. This information is critical for understanding the relative benefits of therapy with systemic IGF-I compared with GH in patients with bowel disease. As well as IGF-I, mucosal mesenchymal cells express three IGFBPs, IGFBP3, IGFBP4 and IGFBP5. Local expression of IGFBPs is altered during adaptive growth of bowel mucosa. The actions of locally expressed IGF-I on mucosal growth likely depend on whether IGF-I is secreted into the extracellular fluid, whether secreted IGF-I associates with secreted IGFBPs and whether IGF-I is sequestered onto the cell surface or extracellular matrix via interactions with IGFBPs. Specific aim 1 will use SMP- IGF-I transgenic mice to test the hypothesis that mesenchymal cell derived IGF-I alters growth and function of bowel in vivo. Small bowel of SMP- IGF-I and WT mice will be compared for mucosal mass, crypt cell proliferation, apoptosis and brush border enzyme activities to define the role of locally expressed, mesenchymal cell derived IGF-I in regulating mucosal growth and function. Specific aim 2 will use IRS-1 null mice and IRS-1 null/SMP- IGF-I crossbreeds tot test the hypothesis that IRS-1 mediates cell specific, trophic actions of IGF-I on bowel. Specific aim 3 will test the hypothesis that differences in expression of IGFs/IGFBPs mediate phenotypic differences in two intestinal fibroblast subtypes and/or their distinct effects on growth and differentiation of intestinal epithelium. For these studies the co-culture system with two phenotypically distinct intestinal fibroblast subtypes that preferentially mediate proliferation (A1:F1 cells) or differentiation (F1:G9 cells) of intestinal endoderm. Specific aim 4 will derive transgenic mice with alpha-SM-actin promoter (SMP) mediated over-expression of des-IGF-I, an analog of IGF-I with low affinity for IGFBPs, to test the hypothesis that IGFBPs modulate the cell specific autocrine/paracrine actions of IGF-I in bowel in vivo.

描述：此修订后的应用程序重点关注角色和机制 胰岛素样生长因子 (IGF-I) 和 IGF 结合蛋白 (IGFBP) 肠道适应。 全身生长激素 (GH) 和 IGF-I 促进 肠道以内分泌方式适应。 IGF-I 介导许多 GH 在肠道中的作用。 GH 和 IGF-I 治疗的临床试验 短肠综合症和其他肠道疾病正在发生。 然而，有 实际上没有关于细胞内机制的直接信息 IGF-I 在肠道中的作用。 小肠粘膜生长的适应性变化 与局部表达的 IGF-I 水平相关，表明旁分泌或 IGF-I 在肠道中的自分泌作用。 GH 增加 IGF-I 的局部表达 小肠内。 局部表达的 IGF-I 在适应性生长中的作用 小肠粘膜的范围尚未明确。 此信息对于 了解全身性 IGF-I 治疗的相对益处 肠道疾病患者服用 GH。 除了 IGF-I 外，粘膜 间充质细胞表达三种 IGFBP：IGFBP3、IGFBP4 和 IGFBP5。 当地的 IGFBP 的表达在肠粘膜适应性生长过程中发生改变。 这 局部表达的 IGF-I 对粘膜生长的作用可能取决于 IGF-I是否分泌到细胞外液中，是否分泌 IGF-I 与分泌的 IGFBP 相关以及 IGF-I 是否被隔离在 通过与 IGFBP 相互作用而进入细胞表面或细胞外基质。 具体目标1将使用SMP-IGF-I转基因小鼠来检验假设 间充质细胞衍生的 IGF-I 改变肠道的生长和功能 体内。 将比较 SMP-IGF-I 和 WT 小鼠小肠的粘膜 质量、隐窝细胞增殖、凋亡和刷状缘酶活性 定义局部表达的间充质细胞来源的 IGF-I 在 调节粘膜生长和功能。 具体目标 2 将使用 IRS-1 null 小鼠和 IRS-1 null/SMP- IGF-I 杂交来测试以下假设： IRS-1 介导 IGF-I 对肠道的细胞特异性、营养作用。 具体的 目标 3 将检验 IGF/IGFBP 表达差异的假设 介导两种肠道成纤维细胞亚型的表型差异和/或 它们对肠道生长和分化的独特影响 上皮。 对于这些研究，共培养系统具有两种表型 优先介导的不同肠道成纤维细胞亚型 肠道的增殖（A1：F1细胞）或分化（F1：G9细胞） 内胚层。 具体目标4将衍生出具有α-SM-肌动蛋白的转基因小鼠 启动子 (SMP) 介导 des-IGF-I（IGF-I 的类似物）的过表达 对 IGFBP 的亲和力较低，以检验 IGFBP 调节的假设 IGF-I 在体内肠道中的细胞特异性自分泌/旁分泌作用。