Bile acid increases expression of the histamine-producing enzyme, histidine decarboxylase, in gastric cells

Figure 4 Bile acid induces histidine decarboxylase expression by caudal-related homeobox 1, which is mediated by small heterodimer partner. A: Human gastric adenocarcinoma (AGS) cells were cotransfected with the 2.3 kb histidine decarboxylase (HDC)-luc promoter construct and caudal-related homeobox (CDX)1 expression plasmid in the presence of deoxycholic acid (DCA) or chenodeoxycholic acid (CDCA). Cells were analyzed for luciferase activity; B: AGS cells were transfected with CDX1 or CDX2 expression plasmid for 48 h. Total RNA was prepared from the cells, after which HDC mRNA levels were determined by reverse transcription-polymerase chain reaction (RT-PCR); C: AGS cells were cotransfected with the 2.3 kb HDC-luc promoter construct and siCDX1/2 constructs and then maintained either under control conditions or in the presence of DCA or CDCA. Cells were analyzed for luciferase activity; D: AGS cells were transfected with siCDX1 construct in the presence of DCA or CDCA. Total RNA was prepared from the cells, after which HDC mRNA levels were determined by RT-PCR; E: AGS cells were cotransfected with the 2.3 kb HDC-luc promoter construct and CDX1/2 expression plasmid or siSHP. Cells were harvested and analyzed for luciferase activity. The experiment was repeated three times in triplicate. ^bP < 0.01 vs mock transfectants.