INTERCELLULAR SIGNALS AND INTESTINAL AGANGLIONOSIS

说明(改编自调查员摘要)： 研究旨在了解肠道无神经节细胞增多症的发病机制 (先天性巨结肠)，该疾病影响5000名活产人类中的1名。这个 神经功能障碍的特征是先天缺乏神经细胞体。 肠道末端继发梗阻 通常需要手术的症状。几个小鼠突变株已经 已经发展成为这种情况的典范。在小鼠和人类中，肠道 无神经节细胞增多症与RET和ET-B基因突变有关 编码由肠道神经前体表达的受体。RET和 ET-B受体是细胞间信号转导通路的组成部分 在胚胎发育过程中运作。内源性内皮素-3缺乏的小鼠 ET-B的配体(ET3)也是无神经节细胞的，但可以通过 肠神经靶向表达ET3的转基因技术 先驱物。拟议研究的目的是确定(1)何时和 成功的肠道定植需要ET-3的表达，(2) 肠神经是否靶向表达ET1(ET3的同源物) 前体将预防ET3缺陷胚胎中的无神经节细胞增多症，(3)是否 ET3的异常表达在其他遗传疾病的发病机制中起作用 与肠道无神经节细胞增多症相关的疾病(Dom/+，ret-/-)和(4) 激活的ras和激活的ret表达对肠道的影响 Dom/+、ret-/-和ET-B-/-突变体中的无神经节细胞增多症。要实现每一项 这些目的，转基因技术将被用来调节时空 上述基因产物在野生型和突变型中的表达 希望改变突变表型的胚胎。出席或缺席 将对无神经节细胞增多症进行组织学和免疫组织化学分析。 生成的数据将定义ET3上的空间和时间约束 胚胎的生产是为了通过以下方式完全定植肠道 肠道神经前体。此外，体内相互作用的证据 在RET、ET-B和它们的细胞内效应器RAS之间寻找 为了弄清楚影响这两个信号的突变是如何 转导途径会导致类似的出生缺陷。这些信息 从这些研究中获得的将成为发展的基础 更有效的诊断、预防和治疗先天性巨结肠的方法 疾病。

DESCRIPTION (adapted from investigator's abstract): The overall goal of the research is to understand the pathogenesis of intestinal aganglionosis (Hirschsprung disease), which affects 1 in 5000 liveborn humans. The disorder is characterized by congenital absence of nerve cell bodies in the terminal portion of the intestinal tract with consequent obstructive symptoms that usually require surgery. Several murine mutant strains have been developed as models for this condition. In mice and humans, intestinal aganglionosis has been associated with mutations in the RET an ET-B genes which encode receptors expressed by enteric neural precursors. The RET and ET-B receptors are components of intercellular signal transduction pathways that operate during embryogenesis. Mice which lack endogenous endothelin 3 (et3), a ligand for ET-B, are also aganglionic, but can be rescued by transgenic techniques which target expression of et3 to enteric neural precursors. The aims of the proposed research are to determine (1) when and where et-3 expression is required for successful enteric colonization, (2) whether targeted expression of et1 (a homolog of et3) by enteric neural precursors will prevent aganglionosis in et3-deficient embryos, (3) whether abnormal et3 expression plays a role in the pathogenesis of other genetic disorders associated with intestinal aganglionosis (Dom/+, ret-/-) and (4) the effects of activated ras or activated ret expression on intestinal aganglionosis in Dom/+, ret-/- and ET-B-/- mutants. To achieve each of these aims, transgenic techniques will be used to regulate spatiotemporal expression of the aforementioned gene products in wild-type and mutant embryos with the hope of altering the mutant phenotype. Presence or absence of aganglionosis will be analyzed histologically and immunohistochemically. The data generated will define spatial and temporal constraints on et3 production in embryos that exist for complete colonization of the gut by enteric neural precursors. In addition, in vivo evidence for interactions between RET, ET-B an on of their intracellular effectors, ras, wil be sought in an effort to clarify how mutations which affect these two signal transduction pathways lead to a similar birth defect. The information gained from these studies wil serve as a foundation for the development of more efficient methods to diagnose, prevent, and perhaps treat Hirschsprung disease.