Compare analysis of the PRNP gene indels polymorphism and expression among Yellow cattle, Zhongdian Yak and their hybrid

Abstract

Background Bovine spongiform encephalopathy (BSE) is a fatal disease in cattle caused by misfolded prion protein and linked to indel polymorphisms in promoter and intron1 of PRNP gene. The aim of this study was to determine the allele, genotype and haplotype frequencies of PRNP indel polymorphisms and to investigate the effect of PRNP gene expression of 23bp and 12bp Indels by Polymerase Chain Reaction (PCR) in Zhongdian Yak (Bos-grunniens) (YK), Zhongdian Yellow cattle (Bos-taurus) (YC) and Zhongdian Yakow (Bos-primigenius taurus×Bos-grunniens) (PK). Resultant, high allelic frequencies were found in 23- and 12+, while haplotype frequencies were very low in 23+/12 in YK, YC and PK. PRNP expression was higher +-/-- diplotype of PK and (mean ± SE) were 3.6578 ± 1.85964. Furthermore, two variable sites were investigated, 23bp indels polymorphism holding AP1-binding site and 12bp indels polymorphism holding SP1-binding site. Additionally, Reporter gene assays revealed a link between two proposed transcription factors and lower expression levels of +/+ allele as compared to -/- allele. The expression level of PRNP was shown to be dependent on two indels polymorphisms in bovine PRNP promoter, which includes binding sites for RP58 and SP1 transcription factors, and results suggested that PRNP genotype may contributing to high variation of PRNP expression.