Enhancement of Intestinal Alkaline Phosphatase Expression by 1,25(OH)2D3 in the Human Intestinal Epithelial-like Cell Line Caco-2

Abstract

Summary : Alkaline phosphatase （ ALP ） hydrolyzes monophosphate esters. Intestinal ALP is localized in the small intestine, and has been suggested to be associated with dietary factors, but the physiological function of intestinal ALP has remained elusive. In this study, we investigated the influence of vitamin D on ALP expression in Caco- 2 cells, which differentiate into human intestinal epithelial-like cells. The cells were incubated for 14 days after reaching confluency, and specific concentrations of 1 , 25（ OH ） 2 D 3 （0 , 10 , and 100 nM ） were added. It was found that the ALP activities and intensities of human intestinal ALP gene expression in the 1 , 25（ OH ） 2 D 3 treated groups （100 nM ） were significantly higher than in the control group （0 nM ） on days 3 , 5 , and 7 . The intensities of sucrase-isomaltase gene expression in Caco- 2 cells were not enhanced by 1 , 25（ OH ） 2 D 3 . The present study has thus demonstrated that expression of intestinal ALP is enhanced by 1 , 25（ OH ） 2 D 3 , and these results will provide useful data for clarifying the novel physiological functions of vitamin D through regulation of human intestinal ALP activity.