Mutation of HPV 18 E6 inhibits the growth of Hela cells and induces apoptosis / 中国生化药物杂志

Objective To construct pcDNA 3.1(+)/HPV 18 E 6 fusion gene and a single-codon mutation pcDNA 3.1(+)/E6 F49R or pcDNA 3.1(+)/E6 F127R fusion gene in eukaryotic expression vector and study the effects on proliferation and apoptosis of cervical carcinoma cell line Hela. Method HPV 18 E6 gene sequence and the single-point mutation HPV 18 E6 F49R or HPV 18 E6 F127R were amplified from total RNA of Hela cell line by reverse transcription- polymerase chain reaction ( RT- PCR), then the gene sequences were respectively inserted into pcDNA 3.1(+) vector to reconstruct recombinant plasmids which were transfected transiently into Hela cells. MTT and RT-PCR were used to test the expression levels of HPV 18 E6 and the growth of HeLa cells after transfected about 48 h. The proliferation and apoptosis of Hela cells were detected respectively by cell counting and AO/EB fluorescent vital staining. Results The pcDNA 3.1(+)/HPV 18 E6, pcDNA 3.1(+)/E6 F49R and pcDNA 3.1(+)/E6 F127R eukaryotic expression vectors were successfully constructed. The gene of HPV 18 E6 was discriminably detected in the HeLa cells which were transfected with the recombinant plasmids. After several days, the proliferation of Hela cells transfected with pcDNA 3.1(+)/E6 F49R or pcDNA 3.1(+)/E6 F127R plasmid were obviously inhibited and the apoptotic rates were significantly increased, then the proliferation of cells transfected with pcDNA(+)/HPV 18 E6 was rather increased slightly, and we could observe the phenomena of early apoptosis and the formation of thekaryopyknosis by fluorescent microscope in the cells transfected with pcDNA 3.1(+)/E6 F49R or pcDNA 3.1(+)/E6 F127R. Conclusion The eukaryotic expressing vectors encoding HPV 18 E6 F49R and HPV 18 E6 F127R provide fundamental basis for the further study on HPV 18 E6 mechanism as well as prevention and treatment of uterine cancer.

Purification and properties of recombinant GST-heparinase III and optimization of cultivation conditions / 生物工程学报

Heparinase III is an enzyme that specifically cleaves certain sequences of heparan sulfate. Previous reports showed that this enzyme expressed in Escherichia coli was highly prone to aggregation in inclusion bodies and lacks detectable biological activity. In this paper, we fused a glutathione-S-transferase (GST) tag to the N-terminus of heparinase III gene and expressed the fusion protein in Escherichia coli to develop an expression system of soluble heparinase III. As a result, approximately 80% of the fusion protein was soluble. The protein was then purified to near homogeneity via one-step affinity chromatography. A 199.4-fold purification was achieved and the purified enzyme had a specific activity of 101.7 IU/mg protein. This represented 32.3% recovery of the total activity of recombinant GST-heparinase III. The maximum enzyme production was achieved when bacteria were induced with 0.5 mmol/L isopropyl-beta-D-thiogalactoside at 15 degrees C for 12 h. The enzyme showed maximum activity at 30 degrees C and pH 7.5. And the enzyme activity was stimulated by 1 mmol/L Ca2+ and 150 mmol/L NaCl.