Effects of Alanyl-Glutamine Dipeptide on Localization and Expression of Tight Junction Protein Occludin in Small Intestinal Epithelial Cells from Piglets

This experiment was conducted to evaluate the effects of alanyl-glutamine dipeptide (Ala-Gln) on localization and expression of tight junction protein occludin in small intestinal epithelial cells from piglets using IPEC-1 cells isolated from jejunal epithelium as the model.The IPEC-1 cells of the same generation were planted into 6-six-well cell culture plates and were incubated with DM EM high-glucose medium containing 0 (control group),0.25,0.50,1.00,2.00,4.00 mmol/L Ala-Gln,respectively.When the cell fusion had reached more than 70%,the immunofluorescence localization and Western Blot of occludin were detected.The results showed as follows: 1) the positive fluorescence staining clouds in cytoplasm of cells were observed in the control group,but that was not obvious among the junction of cells.The fluorescence signals among the junction of cells appeared to be strengthen gradually and the cell outline appeared clearer with the increase of Ala-Gln concentration.Contrarily,the fluorescence signals in cytoplasm of cells were weakened gradually.2) Compared with the control group,the relative expression level of occludin in IPEC-1 cells in supplemental groups was significantly increased (P0.01) and a trend from increase to decrease was observed with the increase of Ala-Gln concentration.The relative expression level of occludin in 2.00 mmol/L group was significantly higher than that in other supplemental groups (P0.01).Therefore,Ala-Gln can up-regulate the expression of tight junction protein occludin in small intestinal epithelial cells from piglets,and promote the formation of intercellular tight junction structure,and then strengthen the barrier function of intestinal mucosa in piglets.