Glutamine Regulates Gene Expression Profiles to Increase the Proliferation of Porcine Intestinal Epithelial Cells and the Expansion of Intestinal Stem Cells

SIMPLE SUMMARY: The intestinal epithelium is one of the tissues that renews the fastest in the body. This process is driven by intestinal stem cells and is greatly influenced by adenosine triphosphate supply. Glutamine is the preferred energy substrate for the intestinal epithelium, unlike most tissues in the body that prefer glucose. However, there needs to be more understanding of how glutamine affects gene expression in the intestinal epithelium. To address this gap, this study aimed to identify the essential genes and signals involved in glutamine-induced growth of intestinal epithelial cells by exploring gene expression profiles. The results showed that glutamine might upregulate deoxyribonucleic acid replication licensing factors, increasing proliferation-related signaling and suppressing inflammation-related pathways. Consequently, this mechanism leads to the proliferation of intestinal epithelial cells and the expansion of intestinal stem cells. Understanding these crucial targets provides new insight into regulating the homeostasis of the intestinal epithelium, particularly in porcine production. ABSTRACT: The intestinal epithelium is known for its rapid self-renewal, and glutamine is crucial in providing carbon and nitrogen for biosynthesis. However, understanding how glutamine affects gene expression in the intestinal epithelium is limited, and identifying the essential genes and signals involved in regulating intestinal epithelial cell growth is particularly challenging. In this study, glutamine supplementation exhibited a robust acceleration of intestinal epithelial cell proliferation and stem cell expansion. RNA sequencing indicated diverse transcriptome changes between the control and glutamine supplementation groups, identifying 925 up-regulated and 1152 down-regulated genes. The up-regulated DEGs were enriched in the KEGG pathway of cell cycle and GO terms of DNA replication initiation, regulation of phosphatidylinositol 3-kinase activity, DNA replication, minichromosome maintenance protein (MCM) complex, and ATP binding, whereas the down-regulated DEGs were enriched in the KEGG pathway of p53 signaling pathway, TNF signaling pathway, and JAK-STAT signaling pathway and GO terms of inflammatory response and intrinsic apoptotic signaling pathway in response to endoplasmic reticulum stress. Furthermore, GSEA analysis revealed a significant up-regulation of the cell cycle, DNA replication initiation, ATP-dependent RNA helicase activity, and down-regulation of the TNF signaling pathway. The protein–protein association network of the intersecting genes highlighted the significance of DNA replication licensing factors (MCM3, MCM6, and MCM10) in promoting intestinal epithelial growth in response to glutamine. Based on these findings, we propose that glutamine may upregulate DNA replication licensing factors, leading to increased PI3K/Akt signaling and the suppression of TNF, JAK-STAT, and p53 pathways. Consequently, this mechanism results in the proliferation of porcine intestinal epithelial cells and the expansion of intestinal stem cells.