INTERCELLULAR SIGNALS AND INTESTINAL AGANGLIONOSIS

描述（改编自研究者摘要）： 研究是为了了解肠道无神经节细胞症的发病机制， 先天性巨结肠（Hirschsprung disease），每5000个活产婴儿中就有1个受影响。 的 疾病的特征是先天性缺乏神经细胞体在 肠道的末端部分，随后阻塞 这些症状通常需要手术治疗。 几种鼠突变株具有 被开发为这种情况的模型。 在小鼠和人类中， 无神经节细胞症与RET和ET-B基因突变有关 其编码由肠神经前体表达的受体。 可再生能源和 ET-B受体是细胞间信号传导途径的组成部分 在胚胎发育过程中起作用。 缺乏内源性内皮素3的小鼠 (et3)，ET-B的配体，也是无神经节的，但可以通过 将ET 3的表达靶向肠神经细胞的转基因技术 前体 本研究的目的是确定（1）何时以及 其中ET-3表达是成功的肠定植所必需的，（2） 是否通过肠神经细胞靶向表达ET 1（ET 3的同源物）， 前体将防止et 3缺陷胚胎中的无神经节细胞症，（3）是否 et 3异常表达在其他遗传性疾病的发病机制中起作用。 与肠无神经节细胞症相关的疾病（Dom/+，ret-/-）和（4） ras或ret表达激活对肠上皮细胞增殖的影响 Dom/+、ret-/-和ET-B-/-突变体中的无神经节细胞症。 为了实现 这些目标，转基因技术将用于调节时空 上述基因产物在野生型和突变体中的表达 希望改变突变表型的胚胎。 存在或不存在 将进行组织学和免疫化学分析。 生成的数据将定义对et 3的空间和时间约束。 在胚胎中产生，这些胚胎存在用于完全定殖肠道， 肠神经前体 此外，体内证据表明， 将寻找RET、ET-B和它们的细胞内效应物ras之间的关系， 为了阐明影响这两种信号突变 转导途径导致类似的出生缺陷。 的信息 从这些研究中获得的信息将作为发展的基础， 更有效的方法来诊断、预防和治疗先天性巨结肠 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.