Background: Notch signaling is required for the maintenance of intestinal epithelial proliferation. Dysfunction of this signaling pathway is associated with the loss of proliferated crypt epithelial cells.
Aim: The aim of this study was to investigate the role of Notch signaling in small bowel resection (SBR)-associated crypt epithelial cell proliferation.
Methods: Male Sprague-Dawley rats were subjected to sham operation (bowel transection and reanastomosis) or 70% mid-SBR. Intestinal tissue samples were collected at 0.5, 1, 6, 12, 24, 72, and 168 h after operation. The expression of Notch pathway mRNAs and proteins was analyzed using RT-PCR and Western blot. The expression of the Notch pathway proteins Jagged-1, NICD and Hes-1 was also determined through immunohistochemical staining using day 3 postoperative intestinal tissues. The degree of crypt epithelial cell proliferation was evaluated using the immunohistochemical staining of proliferating cell nuclear antigen (PCNA). Furthermore, IEC-6 cells were used to examine the function of the Jagged-1 signaling system.
Results: SBR led to increased crypt epithelial cell proliferation and increased expression of Jagged-1 and Hes-1 mRNA and protein along with cleaved Notch-1. Immunohistochemical staining showed that Jagged-1, cleaved Notch-1 and Hes-1 colocalized in the same proliferated crypt epithelial cell population. Recombinant Jagged-1 significantly stimulated the proliferation of IEC-6 cells. Transient upregulation of Jagged-2 expression was found 1 h after SBR, and it was accompanied by cleaved Notch-1 and Hes-1 upregulation.
Conclusion: The Jagged-1/Notch-1/Hes-1 signaling pathway is involved in intestinal adaptation through increasing crypt epithelial cell proliferation.