Glutamine Promotes Porcine Intestinal Epithelial Cell Proliferation through the Wnt/β-Catenin Pathway

Glutamine
(Gln) is a critical nutrient required by neonatal mammals
for intestinal growth, especially for newborn piglets. However, the
mechanisms underlying the role of Gln in porcine intestinal epithelium
development are not fully understood. The objective of the current
study was to explore the possible signaling pathway involved in the
promotion of porcine intestinal epithelial cell (IPEC-J2) proliferation
by Gln. The results showed that 1 mM Gln promoted IPEC-J2 cell proliferation,
and tandem mass tag proteomics revealed 973 differentially expressed
proteins in Gln-treated IPEC-J2 cells, 824 of which were upregulated
and 149 of which were downregulated. Moreover, gene set enrichment
analysis indicated that the Wnt signaling pathway is activated by
Gln treatment. Western blotting analysis further confirmed that Gln
activated the Wnt/β-catenin signaling pathway. In addition,
Gln increased not only cytosolic β-catenin but also nuclear
β-catenin protein expression. LF3 (a β-catenin/TCF4 interaction
inhibitor) assay and β-catenin knockdown demonstrated that Gln-mediated
promotion of Wnt/β-catenin signaling and cell proliferation
were blocked. Furthermore, the inhibition of TCF4 expression suppressed
Gln-induced cell proliferation. These findings further confirmed that
Wnt/β-catenin signaling is involved in the promotion of IPEC-J2
cell proliferation by Gln. Collectively, these findings demonstrated
that Gln positively regulated IPEC-J2 cell proliferation through the
Wnt/β-catenin pathway. These data greatly enhance the current
understanding of the mechanism by which Gln regulates intestinal development.