Increased expression of Semaphorin 3A in the endothelin receptor-B null mouse model of Hirschsprung disease.

PURPOSE: Semaphorins are guidance cues for developing neurons, implicated in the determination of the migratory pathway of neural crest-derived neural precursors during enteric nervous system development. Recently, it has been reported that Semaphorin 3A (SEMA3A) expression is up-regulated in the aganglionic colon in Hirschsprung disease (HD) patients, suggesting that increased SEMA3A expression may be a risk factor for HD. Thus, the aim of our study was to determine the expression of SEMA3A using Sox10-Venus mice gut.

METHODS: We harvested the gut on postnatal day 2 (P2). SOX10-Venus+/EDNRB-/- mice were compared with SOX10-Venus+/EDNRB+/+ mice as controls. QRT-PCR was performed to determine gene expression of SEMA3A (n=8). Fluorescent immunohistochemistry was performed to assess protein distribution.

RESULTS: On P2, gene expression levels of SEMA3A were significantly increased in the HD group compared to controls in the proximal and distal colon (p<0.05). Laser scanning microscopy revealed SEMA3A expression was localized within the submucosa and muscle layer of the gut in both HD and controls. In HD, SEMA3A was highly expressed in the proximal and distal colon.

CONCLUSIONS: In the present study, we demonstrated that SEMA3A expression is increased in the EDNRB-/- HD model on P2, suggesting that SEMA3A may interfere with ENCC migration, resulting in an absence of enteric neurons.