Molecular changes leading to the abnormal migration of sacral neural crest cells in the Dominant megacolon mutant, a mouse model of Hirschsprung's disease

Abstract

Although the majority of neurons and glia of the enteric nervous system (ENS) are derived from neural crest cells (NCCs) at the vagal (cervico‐thoracic) level, NCCs at the sacral level are also able to migrate to the hindgut of the developing embryo and contribute significantly to the ENS of the colon. Abnormal migration of NCCs may lead to a loss of enteric neurons and glial cells in humans, which is called Hirschsprung's disease (HSCR), and also in the Dominant megacolon mouse (Dom), which is an animal model of HSCR carrying a spontaneous mutation of Sox10. In this study, we aimed to follow the migration of sacral NCCs in the mutant embryos and determine the molecular events that lead to the abnormal migration of sacral NCCs. It was found with in situ cell labeling and whole embryo culture that migrating sacral NCCs tended to aggregate, resulting in their delayed migration toward the hindgut. Genome‐wide profiling of RNA expression with microarrays showed that the expression of the adhesion molecule cadherin 19 (Cdh19) was drastically down‐regulated in mutant sacral NCCs as compared to that in the wild‐type. Results of in situ hybridization with wild‐type embryos at E9.5 to E11.5 indicated that Cdh19 was localized to migrating sacral NCCs and their derivatives which also expressed Sox10. With luciferase assay and chromatin immunoprecipitation, the expression of Cdh19 was found to be directly regulated by Sox10, and the binding site of Sox10 on the promoter of Cdh19 was also identified. When the expression of Cdh19 was knockdown in the primary culture of wild‐type sacral NCCs, their migration ability was reduced, and conversely, upon re‐expression of Cdh19 in the mutant sacral NCCs, their migration ability was restored to a level close to that of wild‐type sacral NCCs. Further experiments with immunoprecipitation showed that the Cdh19 expression modulated NCCs migration via interacting with catenins which are important regulators of the dynamic cytoskeleton of migrating NCC. In summary, the present study showed that the Sox10 mutation in the Dom mutant resulted in the delayed migration of sacral NCCs and significant down‐regulation of the expression of Cdh19 which was a direct downstream target of Sox10. Alterations of Cdh19 expression changed the migration ability of sacral NCCs through interactions with catenins which in turn regulated the dynamic cytoskeleton of migrating NCCs.Support or Funding InformationThis work was supported by a RGC General ResearchFund (CUHK14102214) and a Direct Research Grant from the Faculty of Medicine, TheChinese University of Hong Kong (2014.1.074).