Effects of overexpression of the human intestinal alkaline phosphatase gene on the expression of related genes in intestinal epithelium-like cells.

Alkaline phosphatase is an enzyme that hydrolyzes phosphate monoesters. Intestinal-type ALP (IAP), which localizes to the small intestine, is closely associated with dietary factors; however, its physiological functions remain largely unclear. Therefore, we herein hypothesized that the transient overexpression of the human Intestinal Alkaline Phosphatase (ALPI) gene, which encodes IAP, may suggest its effects on the expression of other related genes. Human intestinal epithelium-like Caco-2 cells were transfected with an IAP expression vector or a Mock control to induce transient overexpression. Three days later, Caco-2 cells were harvested and RNA was extracted. Using purified RNA, a comprehensive gene expression analysis was performed by RNA sequencing with next-generation sequencing technology. In comparisons with the Mock control, 1036 differentially expressed genes (DEGs) were identified in Caco-2 cells transfected with the human IAP expression vector. The expression of 79 of these genes was more than two-fold higher, while that of 74 of these genes was more than two-fold lower. The GO analysis of the 79 up-regulated genes demonstrated that seven genes were enriched in "nervous system development" and three genes in "negative chemotaxis". In contrast, the GO analysis of the 74 down-regulated genes demonstrated that two genes were enriched in "membrane repolarization during atrial cardiac muscle cell action potential", four genes in "cell surface receptor signaling pathway", five genes were enriched in "neuron projection", and three genes in "perikaryon". Further studies are warranted to investigate the relationships between DEGs and the regulation of ALPI gene expression in more detail.