[Objective] To investigate the possibilities of expressing bovine PrP27-30 gene in CHO-K1 cells. [Method] The purified PCR products of PrP27-30 were digested and ligated to the pCI-neo vector to yield pCI-neo-PrP27-30 that was used as an expression vector. Then CHO-K1 cells were transfected by pCI-neo-PrP27-30, and stable expression clone cells were screened by methotrexate (MTX) at a concentration of 0.1 and 1.0 umol/L. The transient expression was detected by indirect immunofluorescence assay and western blot. [ Result] After drug selection with MTX, the expression of PrP27-30 gene was detected in CHO-K1 cells. [Conclusion] Recombinant protein PrP27-30 expressed in CHO-K1 cells has better immunoreactivity and can be used to study secondary structure and regulation mechanism of pathological isoform of prion protein (prpC).
Bovine spongiform encephalopathy （BSE） is thought to be caused by prions initially derived from sheep scrapie, and epidemiological studies suggest that new viriant form of CJD manifest in Great Britain may be caused by BSE prions. PrP^Sc is thought to pathogenic factor of transmissible spongiform encephalopathy （TSE）, which invariably involve a post-translational modification process of PrPc encoded by the host euchromosome PrP gene during the period it converted into the pathogenic form （PrP^Sc）, PrP is nomal cellular protein which has been found in both neuronal and nonneuronal tissues. Since the crucial infectious event in protein-transmitted diseases is an induced misfolding of prion proteins （PrP^c） catalyzed by already misfolded PrP^Sc, it is of high importance that such collisions are enhanced by two-dimensional diffusion in cell membranes is of high importance compared to three-dimensional diffusion in solution. The level of PrP mRNA in brain is higher than other tissue, but purification of PrPc from rodent has been difficult. To understand the formation of PrP^Sc, it seemed useful to develop a system for produced a large quantities of PrPc since there is no nature source of PrP^c. The pCI-neo mammalian expression vector contains the neomycin phosphtransferase gene which serves as a marker for the selection of stable transfected cells with G418. COS-7 cells constitutively express simian viruse 40 （SV40） T-antigen and support replication of expression plasmids containing the SV40 origin of replication, amplifying the introduced expression cassettes, now become important routine of expression a large number of heterologous gene products. In this paper, the authors used pCI-neo vector to construct a recombnant pCIp264 （cotains mPrP, N-signalpeptide and C-GPI anchor） plasmid to express it in the COS-7 cells and meanwhile detect the expression fusion using IN-ELISA, IN-IFA and western blot, and obtain some approximative nature PrPc.
Yaozhong Ding Yongsbeng Liu Wenqian Liu Yanping Ma Meng Wang Shenghai Yang Jie Zhang
