Bovine spongiform encephalopathy (BSE) is one of the fatal neurodegenerative diseases known as transmissible spongiform encephalopathies (TSEs) caused by infectious prion proteins. Genetic variations correlated with susceptibility or resistance to TSE in humans and sheep have not been reported for bovine strains including those from Holstein, Jersey, and Japanese Black cattle. Here, we investigated bovine prion protein gene (PRNP) variations in Hanwoo cattle [Bos (B.) taurus coreanae], a native breed in Korea. We identified mutations and polymorphisms in the coding region of PRNP, determined their frequency, and evaluated their significance. We identified four synonymous polymorphisms and two non-synonymous mutations in PRNP, but found no novel polymorphisms. The sequence and number of octapeptide repeats were completely conserved, and the haplotype frequency of the coding region was similar to that of other B. taurus strains. When we examined the 23-bp and 12-bp insertion/deletion (indel) polymorphisms in the non-coding region of PRNP, Hanwoo cattle had a lower deletion allele and 23-bp del/12-bp del haplotype frequency than healthy and BSE-affected animals of other strains. Thus, Hanwoo are seemingly less susceptible to BSE than other strains due to the 23-bp and 12-bp indel polymorphisms.
Animals ; Base Sequence ; Cattle ; DNA/genetics ; Encephalopathy, Bovine Spongiform/*genetics ; *Genetic Variation ; Haplotypes ; Prions/*genetics ; Republic of Korea

It is one of the frequently utilized strategies for positive-negative selection to elevate the gene targeting efficiency in somatic cells by enriching targeted colonies. Knocking out prnp in animals by gene targeting can prevent it from expressing Prion protein (Pathogenic protein of transmissible spongiform encephalopathy), which enables it to resist infection of Prion. We constructed a bovine prnp biallelic targeting vector via the positive-negative selection strategy, and transfected the linearized vector into the bovine fetal fibroblasts through electroporation. Then, we selected cells in cell culture medium with G418 under a concentration of 600 microg/mL followed by Ganciclovir (GCV) under a concentration of 200 nmol/mL. In the end, we successfully obtained 176 cell clones. All these clones were identified by means of sequencing, immunofluorescence and western blotting, respectively, confirming that there existed 9 positive cell clones. The results showed that the bovine prnp gene was successfully knocked out. Conclusively, we provide an effective way to knockout bovine prnp gene, which could serve as the basis for producing prion protein gene knockout transgenic cloned cattle.
Animals ; Cattle ; Electroporation ; Encephalopathy, Bovine Spongiform ; genetics ; Fetus ; cytology ; Fibroblasts ; cytology ; metabolism ; Gene Knockout Techniques ; methods ; Gene Targeting ; Genetic Vectors ; genetics ; Prions ; genetics ; Transfection

A normal prion protein (PrPc) is converted to a proteaseresistant isoform by an apparent self-propagating activity in transmissible spongiform encephalopathy, a neurodegenerative disease. The cDNA encoding open reading frame (ORF) of the bovine prion protein gene (Prnp) was cloned from Korean cattle by PCR, and was transfected into Chinese hamster ovary (CHO-K1) cells using lipofectamine. The gene expression of the cloned cDNA was confirmed by RT-PCR and Western blotting with the monoclonal antibody, 6H4. Cellular changes in the transfected CHO-K1 cells were investigated using parameters such as MTT, lactate dehydrogenase (LDH), and superoxide dismutase (SOD) activities, as well as nitric oxide (NO) production, and an apoptosis assay. In the MTT and LDH assays, the bovine PrnP-transfectant showed a lower proliferation rate than the wild-type (p < 0.05). Production of NO, after LPS or ConA stimulation, was not detected in either transfectants or CHO-K1 cells. In SOD assay under ConA stimulation, the SOD activity of transfectants was 10 times higher than that of CHO-K1 cells at 6 h after treatment (p < 0.05). The genomic DNA of both the transfectants and control cells began to be fragmented at 6 h after treatment with cyclohexamide. Caspase-3 activity was reduced by transfection with the bovine Prnp (p < 0.05). Conclusively, the viability of transfectants expressing exogenous bovine Prnp was decreased while the capacities for cellular protection against antioxidative stress and apoptosis were increased.
Animals ; Apoptosis/physiology ; CHO Cells/cytology/enzymology/*physiology ; Caspase 3/metabolism ; Cattle ; Cell Growth Processes/physiology ; Cloning, Molecular ; Cricetinae ; Cricetulus ; Encephalopathy, Bovine Spongiform/genetics/*pathology ; Formazans ; Hydro-Lyases/metabolism ; Nitric Oxide/metabolism ; Prions/biosynthesis/genetics/*physiology ; Superoxide Dismutase/metabolism ; Tetrazolium Salts ; Transfection