Functional characterization of the chicken peptide transporter 1 (pept1, slc15a1) gene

Dietary amino acids can be transported into intestinal epithelial cells as di- and tripeptides by the action of the peptide transporter, PepT1 (SLC15A1). Expression of the chicken PepT1 (cPepT1) gene changes in response to dietary crude protein level; however, the molecular mechanism governing this regulation is unknown. This study analyzed the promoter region of the cPepT1 gene. Using deletion analysis, positive-acting (-314 to -261, -169 to -155, and -120 to -60) and negative-acting (-419 to -386 and -214 to -169) regions were mapped in transfected chick embryo fibroblasts (CEF). The addition of neither amino acids Phe, Arg, or Val, nor the dipeptides Gly-Sar (glycyl-sarcosine), Gly-Pro, Gly-Phe, Met-Pro, Met-Lys or Lys-Lys, had an effect on cPepT1 promoter activity in transfected CEF. The cPepT1 promoter was more active in CEF and primary chicken intestinal cells than in chicken liver cells. This study represents a functional characterization of the molecular regulation of the chicken PepT1 gene.