OBJECTIVETo express, purify and refold recombinant luteinizing hormone releasing hormone-angiogenin (LHRH-Ang) toxin using E. coli. expression system.

METHODSRecombinant LHRH-Ang expression vector was constructed by replacing of EGF fragment in plasmid pET28a/EGF-Ang with LHRH-PII fragment amplified from plasmid pET28/MSH-PE40. DNA sequencing would be used to verify the correction of fused LHRH-PII-Ang gene. Then, E. coli strain BL21 (DE3) was transformed by pET28a/LHRH-Ang vector. Expression of recombinant LHRH-Ang toxin was induced by Isopropyl-β-D-Thiogalactoside (IPTG). Refolding effects of gradient dialysis was evaluated by SDS-PAGE.

RESULTSProkaryotic expression vector pET28a/LHRH-Ang, containing LHRH-PII-Ang fusion gene, was constructed by PCR amplification, restriction enzyme digestion and ligation method. Sequence correction of fusion gene was confirmed by DNA sequencing. After IPGT induction, recombinant LHRH-Ang protein was expressed in BL21 (DE3) as inclusion body, it took 18.43% of total protein. Inclusion body was resolved in 8 mol/L urea and purified by DEAE-Sepharose FF column, the purity was 85%. Recombinant LHRH-Ang toxin was refolded and concentrated by gradient dialysis and PEG 20000, respectively.

CONCLUSIONSRecombinant LHRH-Ang protein was expressed in E. coli and refolded successfully.

Escherichia coli ; metabolism ; Gene Expression ; Genetic Vectors ; Gonadotropin-Releasing Hormone ; biosynthesis ; genetics ; Plasmids ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; Ribonuclease, Pancreatic ; biosynthesis ; genetics

This study was purposed to investigate the angiogenin (ANG) expression in COS-7 cells and its biological activity. The gene of angiogenin was obtained from mononuclear cells of peripheral blood by using RT-PCR and inserted into eukaryotic expression vector of pcDNA3.1. After being transfected into COS-7 cells, the recombinant ANG was identified by Western blot assay. The function of promoting proliferation of ANG to ECV304 cells was detected by MTT method, and its activity of vascularization was analyzed by chick embryo chorioallantois treated by the culture supernatant after transfection with pcDNA3.1-ang. The result showed that recombinant ANG was expressed in COS-7 cells after transfection for 24 to 36 hours. It could specifically react with monoclonal antibody against ANG. The recombinant ANG could obviously promote the proliferation of ECV304 cells. In contrast with the control group, the culture supernatant of pcDNA3.1-ang transfected group could stimulate the angiogenesis in embryo chorioallantois. It is concluded that the ang transiently expresses in COS-7 cells, and its expression product obviously stimulates the cell proliferation and angiogenesis.
Angiogenesis Inducing Agents ; pharmacology ; Animals ; COS Cells ; metabolism ; Cell Line ; Cell Proliferation ; drug effects ; Cercopithecus aethiops ; Endothelial Cells ; cytology ; Genetic Vectors ; genetics ; Humans ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; pharmacology ; Ribonuclease, Pancreatic ; biosynthesis ; genetics ; pharmacology ; Transfection

To develop a novel therapeutic angiogenesis for the treatment of cardiovascular diseases, angiogenin (ANG1) was examined as a potential therapeutic gene. An adeno-associated virus (AAV)-mediated gene delivery system was used to measure the therapeutic efficacy of ANG1. Using a triple co-transfection technique, rAAV-ANG1-GFP, rAAV- VEGF-GFP and rAAV-GFP vectors were produced, which were then used to infect human umbilical vein endothelial cells (HUVECs) in order to evaluate in vitro angiogenic activities. Their protein expressions, tagged with green fluorescent protein (GFP), were monitored by confocal microscopy. The functional activities were measured using wound-healing HUVEC migration assays. The number of migrated cells stimulated by both the expressed ANG1 and the VEGF in rAAV-infected HUVECs increased almost twice the number observed in the expressed GFP control. In vivo angiogenic activities of the expressed ANG1 or VEGF were determined using mouse angiogenesis assays. The angiogenic activities of ANG1 or VEGF expressed in the injected mice were increased by 1.36 and 2.16 times, respectively, compared to those of the expressed GFP control. These results demonstrate that the expressed ANG1 derived from rAAV infection has in vitro and in vivo angiogenic activities and suggest that the rAAV-ANG1 vector is a potential strategy for therapeutic angiogenesis.
Animals ; Cell Movement ; Cells, Cultured ; Dependovirus/*genetics ; Endothelial Cells/metabolism/*physiology ; *Gene Transfer Techniques ; Genetic Vectors ; Humans ; Male ; Mice ; Mice, Inbred C57BL ; *Neovascularization, Physiologic ; Ribonuclease, Pancreatic/biosynthesis/*genetics ; Umbilical Veins/cytology ; Vascular Endothelial Growth Factor A/biosynthesis