Functional characterization of genetic polymorphisms identified in the promoter region of the bovine PEPS gene.

Peptidase S (PEPS) is a metallopeptidase that cleaves N-terminal residues from proteins and peptides. PEPS is used as a cell maintenance enzyme with critical roles in peptide turnover. The promoter region located upstream of the initiation site plays an important role in regulating gene expression. Polymorphism in the promoter region can alter gene expression and lead to biological changes. In the current study, polymorphisms in the promoter region of the PEPS gene were investigated. Polymerase chain reaction (PCR)-restriction fragment length polymorphism and DNA sequencing methods were used to screen sequence variations in the promoter region of DNA samples from 743 Chinese Holstein cattle. Two polymorphisms (g. -534 T>C and g. -2545 G>A) were identified and eight haplotypes were classified by haplotype analysis. The two genetic polymorphisms and haplotypes were associated with fat percentage and somatic cell score in Chinese Holstein cattle. The results of real-time PCR showed that cow kidneys exhibit the highest PEPS expression level. Moreover, bioinformatics analysis predicted that the single-nucleotide polymorphism g. -534 T>C is located in the core promoter region and in the transcription factor binding sites. The promoter activities of the polymorphism of -543 T>C were measured by luciferase assay in the human kidney epithelial cell line 293T. Transcriptional activity is significantly lower in cell lines transfected with the reporter construct containing 2.5 kb upstream fragments with -543 C than in those with wild-type -543 T. The results indicated that genetic variation at locus -543 influences PEPS promoter activity. The genetic variation in the promoter region of PEPS gene may regulate PEPS gene transcription and might have consequences at a regulatory level.