Advances in the application of yeast surface display technology / 生物工程学报

Yeast surface display (YSD) is a technology that fuses the exogenous target protein gene sequence with a specific vector gene sequence, followed by introduction into yeast cells. Subsequently, the target protein is expressed and localized on the yeast cell surface by using the intracellular protein transport mechanism of yeast cells, whereas the most widely used YSD system is the α-agglutinin expression system. Yeast cells possess the eukaryotic post-translational modification mechanism, which helps the target protein fold correctly. This mechanism could be used to display various eukaryotic proteins, including antibodies, receptors, enzymes, and antigenic peptides. YSD has become a powerful protein engineering tool in biotechnology and biomedicine, and has been used to improve a broad range of protein properties including affinity, specificity, enzymatic function, and stability. This review summarized recent advances in the application of YSD technology from the aspects of library construction and screening, antibody engineering, protein engineering, enzyme engineering and vaccine development.

Design,preparation and screening of siRNA of proliferating cell nuclear antigen / 中国病理生理杂志

AIM: To design,prepare and screen out functional small interfering RNA(siRNA) for specifically silencing proliferating cell nuclear antigen(PCNA) gene expression and effectively inhibiting cell proliferation on human hepatoma cell line SMMC-7721,human gastric carcinoma cell line SGC-7901 and human colorectal carcinoma cell line Caco2.METHODS: PCNA siRNA was designed based on previous studies about design guidelines and synthesized in vitro by T7 Mega short script reaction kit according to the manufacturer's instructions.After purification,the integrities of siRNA were identified through 19% denaturing polyacrylamide gel electrophoresis,and the concentrations of the generated siRNA were measured by testing the absorbance at 260 nm using a spectrophotometer.Four synthesized double-strand siRNA were transfected into three types of carcinoma cell lines by LipofectamineTM2000 reagent,respectively.WST-8 assay was employed to examine the proliferative inhibitions of these three cell lines.The subsequent alterations on PCNA mRNA and protein levels were determined by semi-quantitative reverse transcription-polymerase chain reaction(RT-PCR) and immunocytochemistry,respectively.RESULTS: 3 sequences,No.2,No.3 and No.4 PCNA siRNA showed effective inhibitions on tumor cells among the 4 candidate siRNA,and a single dose of 50 nmol/L of No.2,No.4 PCNA siRNA showed the most effective inhibitory rates as more than 62% at 48 h after transfection.50 nmol/L of No.2 and No.4 PCNA siRNA transfection caused 72% decrease of PCNA mRNA level and almost completely loss of the protein in human Caco2 cells.CONCLUSION: No.2 and No.4 PCNA siRNA have been screened out in this study,which show the capability to effectively down-regulated PCNA expression and significantly inhibit the proliferation of carcinoma cells.The optimal concentration is 50 nmol/L and satisfactory effects are achieved 48 h after transfection in vitro.