INTESTINAL ADAPTATION--ROLE OF HORMONES & GROWTH FACTORS

描述：此修订后的应用程序侧重于角色和机制 胰岛素样生长因子（IGF-I）和胰岛素样生长因子结合蛋白（IGFBPs）在 肠道适应 全身生长激素（GH）和IGF-I促进 肠道内分泌的适应。 IGF-I介导了许多 GH在肠道中的作用。 生长激素和胰岛素样生长因子-I治疗糖尿病的临床试验 短肠综合征和其他肠道疾病正在进展中。 然而， 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在肠中的自分泌作用。 GH增加IGF-I的局部表达 在小肠内。 局部表达的IGF-I在适应性生长中的作用 小肠粘膜的厚度没有定义。 这些信息对于 了解全身性IGF-I治疗的相对获益， 与肠道疾病患者的生长激素有关。 以及IGF-I，粘膜 间充质细胞表达三种IGFBPs，IGFBP 3、IGFBP 4和IGFBP 5。 当地 IGFBPs的表达在肠粘膜的适应性生长期间改变。 的 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IGFBPs相关，以及IGF-I是否被隔离在 细胞表面或细胞外基质通过与IGFBPs的相互作用。 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改变了肠道的生长和功能， vivo. 将比较SMP-IGF-I和WT小鼠的小肠的粘膜损伤。 质量、隐窝细胞增殖、凋亡和刷状缘酶活性 为了确定局部表达的间充质细胞衍生的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无效/SMP-IGF-I杂交以检验假设， IRS-1介导IGF-I对肠的细胞特异性营养作用。 具体 目的3将检验IGFs/IGFBPs表达差异的假设， 介导两种肠成纤维细胞亚型的表型差异，和/或 它们对肠上皮细胞生长和分化的影响 上皮 对于这些研究，具有两种表型的共培养系统 不同的肠成纤维细胞亚型， 肠上皮细胞增殖（A1：F1细胞）或分化（F1：G9细胞） 内胚层 具体目标4将获得具有α-SM-肌动蛋白的转基因小鼠 启动子（SMP）介导的IGF-1类似物des-IGF-I的过表达 与IGFBPs的亲和力低，以检验IGFBPs调节 IGF-I在体内肠道中的细胞特异性自分泌/旁分泌作用。

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.