Decreased expression of NEDL2 in Hirschsprung's disease

NEDD4-like ubiquitin protein ligase 2 (NEDL2) plays an important role in many physiological and pathological processes. NEDL2 is a positive regulator of GDNF/Ret signaling during enteric neurogenesis. Mice lacking NEDL2 exhibit decreased numbers of enteric neurons, progressive bowel dysmotility and intestinal hypoganglionosis. We designed this study to investigate the expression of NEDL2 in the normal human colon and in HSCR.

HSCR tissue specimens (n=10) were collected at the time of pull-through surgery and divided into aganglionic and ganglionic segments. Colonic control samples (n=10) were obtained from patients with imperforate anus at the time of colostomy closure. Immunolabeling of NEDL2 was visualized using confocal microscopy to assess protein distribution, while Western blot analysis was undertaken to quantify NEDL2 protein expression.

Confocal microscopy revealed that NEDL2-immunoreactivity colocalized with ICCs and neurons within the submucosa, myenteric plexus and smooth muscle in controls and ganglionic specimens, with markedly reduced NEDL2-immunoreactivity in aganglionic specimens. Western blotting revealed high levels of the NEDL2 protein in normal controls and the ganglionic region of HSCR, while there was a marked decrease in NEDL2 protein expression in the aganglionic region of HSCR.

We report, for the first time, the expression of NEDL2 in the human colon. The decreased expression of NEDL2 in the aganglionic colon suggests that NEDL2 may play a role in the pathophysiology of HSCR.