Porcine DJ-1: cloning of PARK7 cDNA, sequence comparison, expression analysis and chromosomal localization

The PARK7 gene encodes a protein, DJ-1, with several functions such as protection of cells from oxidative stress, sperm maturation and fertilization and chaperone activity. Mutations in the PARK7 gene are associated with autosomal recessive early-onset Parkinson's disease (Parkinsonism). This work reports the cloning and analysis of the porcine (Sus scrofa) homologue of DJ-1. The porcine PARK7 cDNA was amplified by reverse transcriptase polymerase chain reaction (RT-PCR) using oligonucleotide primers derived from in silico sequences. The porcine PARK7 cDNA (SsPARK7) encodes a protein of 189 amino acids which shows a very high similarity to bovine (97%), to human (96%) and to canine (95%) DJ-1. Protein structure comparison of human and porcine DJ-1 sequences revealed that amino acid changes were few between the two species and not likely to alter DJ-1 structure and function. Quantitative real-time RT-PCR detection exhibited SsPARK7 mRNA expression in all analyzed porcine tissues, although at different levels. Furthermore, expression analysis showed that SsPARK7 transcripts could be detected early in embryo development in different brain regions. The PARK7 gene was demonstrated to be located on porcine chromosome 6. Single-nucleotide polymorphism (SNP) analysis revealed one SNP in the porcine PARK7 gene, giving rise to a silent mutation in exon 6.