Background. The yeast Pichia pastoris is used for synthesis of recombinant secretory proteins. Overexpression of assistant genes, coding proteins involved in secretion, is one of approaches to improve the production of target protein. PpPDI gene encodes P. pastoris yeast protein disulfide isomerase (Pdi). The aim of our study was to evaluate the effect of Pdi overproduction on recombinant interferons (human interferon-alfa16 and chicken interferon-gamma) production. Materials and Methods. PpPDI gene was cloned under the control of the AOX1 gene promoter in plasmid pPICZαA. Primers for AJ302014.1 nucleotide sequence of NCBI data base were used for PpPDI gene cloning. The chromosomal DNA of the GS115 strain was used as a template. To generate strains with PpPDI gene overexpression we used a previously obtained strains producing human interferon-alfa16 and chicken interferon-gamma. Yeast transformation was performed by electroporation. Cultivation was performed using single and two-stage strategies in standard media containing methanol as the sole carbon source to induce the AOX1 gene promoter. Results. We obtained interferon-producing strains with PpPDI gene overexpression. Over-expression of the PpPDI gene in yeast P. pastoris increases the production of interferon-alfa16, a protein containing disulfide bonds, regardless of the mode of cultivation. Effect of PpPDI gene over-expression on the production of interferon-gamma - the protein without disulfide bonds, depends on cultivation mode. Conclusion. PpPDI gene overexpression can be used to enhance the production of interferons and other proteins that contain disulfide bonds. Effect of PpPDI gene overexpression on recombinant proteins without disulfide bonds may depend on cultivation procedure.
The objective of the study was to assess articular cartilage (AC) and subchondral bone (SCB) remodeling, expression of matrix metalloproteinase 9 (MMP-9) in tissues, vascular endothelial growth factor (VEGF) in experimental osteoarthritis (OA). Material and methods Experimental comparative study was conducted on 12 outbred guinea pigs of both sexes aged 28-30 weeks that were divided into 2 groups of 6 animals each. An injury to the knee joints of hind limbs of control and experimental animals was mechanically simulated by closed scarification using a sterile needle. No treatment was provided for controls. Experimental animals were given an intraarticular injection of betamethasone (BMZ) of 0.1 mg/kg every two weeks after two weeks of injury. Two subjects of each group were euthanized at 30, 45, 60 days and knee samples collected. Immunohistochemical expression of VEGF and MMP-9 was determined in tissues. Results A statistically significant decrease in VEGF positive chondrocytes and precipitate density, an increase in positive chondrocytes and intensity of tissue response to MMP-9 as compared to those in controls was observed in BMZ animals at 30 days of experiment. A statistically significant decrease in VEGF positive cells and precipitate density, an increase in VEGF positive chondrocytes as compared to those in controls were observed in BMZ animals at 45 days of experiment. Significant reduction in VEGF positive cells and deposit density, significantly higher density of MMP-9 positive precipitates as compared to those in controls were noted at 60 days of BMZ injections. Conclusion Intraarticular injections of BMZ demonstrated a negative effect on AC and SCB with articular tissue remodeling initiated through activation mechanisms of extracellular matrix degradation, as evidenced by high expression of MMP-9. BMZ was shown to block pathological angiogenesis via VEGF inhibition.
Genes encoding truncated versions of bovine and chicken gamma interferon genes lacking pre dicted protease cleavage sites at the C terminus were constructed and expressed in the yeast Pichia pastoris. The recombinant proteins possessed increased stability in comparison with the corresponding wild type gamma interferons while retaining biological activity. The recombinant strains provide a useful tool for the purification of bovine and chicken gamma interferons for their use in veterinary applications.
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