跳跃型巨结肠中节段性肠神经的胚胎学来源及其形成的分子机制研究

先天性巨结肠为儿童常见先天性疾病，致病原因为神经嵴细胞沿肠道迁移缺陷导致肠道远端的神经节细胞缺失。跳跃型巨结肠是指无神经节肠段内存在一段有节细胞，为一种罕见先天性巨结肠类型。由于肠神经发育理论无法解释该段有节细胞的胚胎学来源，跳跃型巨结肠发病原因和临床诊断一直存在争议。我们前期筛选到两例跳跃型巨结肠病例，并在Ednrb基因敲除小鼠模拟出跳跃型巨结肠表型。我们发现部分神经嵴细胞经肠系膜迁移进入肠道，提示该部分神经嵴细胞为跳跃型巨结肠中节段性肠神经的胚胎学来源。在本项目中，我们将继续利用临床标本和转基因小鼠，结合遗传谱系追踪、组织培养和共聚焦实时成像等技术，系统阐明：1）跳跃型巨结肠中节段性肠神经起源于跨肠系膜神经嵴细胞; 2）ET3/EDNRB信号通路调控跨肠系膜神经嵴细胞迁移的分子机制。研究成果将对肠神经发育和先天性巨结肠发病机制提供新的洞见，并为跳跃型巨结肠的临床诊断和治疗提供理论指导。

Defective colonization of the gastrointestinal tract by neural crest cells (NCCs) results in Hirschsprung’s disease (HSCR), which is a congenital intestinal disorder and characterized by the absence of enteric neurons in variable lengths of the distal bowel. Skip segment Hirschsprung’s disease (SSHD), a rare variant of HSCR involving single ganglionated segment within an otherwise aganglionic intestine, contradicts the current consensus of the pathogenesis of HSCR. We previously identified two SSHD cases from 56 HSCR patients，and revealed that Ednrb-/- mice, a mouse model for HSCR, recapitulated the phenotype of SSHD, thus providing supportive evidence for the presence of SSHD. Additionally, we preliminarily found that a subset of NCCs migrated into the gut via the gut mesentery to make complementary contribution to the enteric neurons. Therefore, we hypothesize that mesenteric NCCs (mNCCs), which invade the gut from the gut mesentery, are the embryologic basis of SSHD. In this project, we will employ genetic cell lineage tracing and in vitro live imaging with confocal microscope in mouse, together with human intestinal samples from HSCR patients, to address the following two questions: 1) whether mNCCs are the embryological basis underlying SSHD? 2) what are the roles of EDNRB/ET3 signaling pathway in regulating the migration of mNCCs? Our findings will provide novel insights into the development of the enteric nervous system and the etiology of digestive disorders.