Propofol protects against oxidative-stress-induced COS-7 cell apoptosis by inducing autophagy

BACKGROUND: In oxidative stress, reactive oxygen species (ROS) production contributes to cellular dysfunction and initiates the apoptotic cascade. Autophagy is considered the mechanism that decreases ROS concentration and oxidative damage. Propofol shows antioxidant properties, but the mechanisms underlying the effect of propofol preconditioning (PPC) on oxidative injury remain unclear. Therefore, we investigated whether PPC protects against cell damage from hydrogen peroxide (H₂O₂)-induced oxidative stress and influences cellular autophagy. METHOD: COS-7 cells were randomly divided into the following groups: control, cells were incubated in normoxia (5% CO₂, 21% O₂, and 74% N₂) for 24 h without propofol; H₂O₂, cells were exposed to H₂O₂ (400 µM) for 2 h; PPC + H₂O₂, cells pretreated with propofol were exposed to H₂O₂; and 3-methyladenine (3-MA) + PPC + H₂O₂, cells pretreated with 3-MA (1 mM) for 1 h and propofol were exposed to H₂O₂. Cell viability was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide thiazolyl blue (MTT) reduction. Apoptosis was determined using Hoechst 33342 staining and fluorescence microscopy. The relationship between PPC and autophagy was detected using western blot analysis. RESULTS: Cell viability decreased more significantly in the H₂O₂ group than in the control group, but it was improved by PPC (100 µM). Pretreatment with propofol effectively decreased H₂O₂-induced COS-7 cell apoptosis. However, pretreatment with 3-MA inhibited the protective effect of propofol during apoptosis. Western blot analysis showed that the level of autophagy-related proteins was higher in the PPC + H₂O₂ group than that in the H2O2 group. CONCLUSION: PPC has a protective effect on H₂O₂-induced COS-7 cell apoptosis, which is mediated by autophagy activation.

Remifentanil induces autophagy and prevents hydrogen peroxide-induced apoptosis in Cos-7 cells

BACKGROUND: This study investigated the effect of remifentanil pretreatment on Cos-7 cells exposed to oxidative stress, and the influence of remifentanil on intracellular autophagy and apoptotic cell death. METHODS: Cells were divided into 4 groups: (1) Control: non-pretreated cells were incubated in normoxia (5% CO₂, 21% O₂, and 74% N₂). (2) H₂O₂: non-pretreated cells were exposed to H₂O₂ for 24 h. (3) RPC+H₂O₂: cells pretreated with remifentanil were exposed to H₂O₂ for 24 h. (4) 3-MA+RPC+H₂O₂: cells pretreated with 3-Methyladenine (3-MA) and remifentanil were exposed to H₂O₂ for 24 h. We determined the cell viability of each group using an MTT assay. Hoechst staining and FACS analysis of Cos-7 cells were performed to observe the effect of remifentanil on apoptosis. Autophagy activation was determined by fluorescence microscopy, MDC staining, and AO staining. The expression of autophagy-related proteins was observed using western blotting. RESULTS: Remifentanil pretreatment increased the viability of Cos-7 cells exposed to oxidative stress. Hoechst staining and FACS analysis revealed that oxidative stress-dependent apoptosis was suppressed by the pretreatment. Additionally, fluorescence microscopy showed that remifentanil pretreatment led to autophagy-induction in Cos-7 cells, and the expression of autophagy-related proteins was increased in the RPC+H₂O₂ group. CONCLUSIONS: The study showed that remifentanil pretreatment stimulated autophagy and increased viability in an oxidative stress model of Cos-7 cells. Therefore, we suggest that apoptosis was activated upon oxidative stress, and remifentanil preconditioning increased the survival rate of the cells by activating autophagy.

Cloning,weukaryotic expremion of the gene encoding glyceraidehydes-3-phosphate dehydrogenase fromperiodic Brugia malayi / 中国地方病学杂志

Objective To clone and express the encoding sequence of glyceraldehydes-3-phosphate dehydrogenase(GAPDH)from periodic Brugia molayi(Bm).Methods Total RNA was extraeted from periodic Brugic malayi.The BmGAPDH gene was amplified by RT-PCR.The PCR product was cloned and then subeloned into pcDNA3.1(+)vector.The recombinant plasmids were screened and identified by digestion with restriction enzyme and PCR amplification,and were transformed into COS-7 cell subsequently.The expressed protein was identified by SDS-PAGE.Results BmGAPDH mRNA was highiy expressed in transfected COS-7 cell.The deduced amino acid sequence was identical with that of BmGAPDH.The recombinant pnotein wag about Nr 43 000.Conclusion The recombinant plasmid peDNA3.1(+)-BmGAPDH has been constructed and the protein has been expressed correctly.

Construction of Porcine CCK pDNA and Its Expression in COS-7 Cells / 华中科技大学学报（医学）（英德文版）

CCK correlates with the generation and progression of pancreatic cancer. The research aims to construct eukaryotic expression plasmid pIRES2-EGFP/CCK (CCK pDNA) and transiently express it in COS-7 cells. Total RNA was extracted from porcine intestinal mucosa. RT-PCR was used to amplify the aimed segments CCKcDNA which was then digested with EcoR1 and BamH1 and inserted into a eukaryotic expression plasmid pIRES2-EGFP to construct CCK pDNA. The constructed plasmid was transfected into COS-7 cells by lepofectamine TM2000-mediated transfer method.The expression of CCK in transfected COS-7 cells was detected 24, 48 and 72 h post-transfection with fluorescence microscopy and the expression level of CCK mRNA in transfected COS-7 cells was assayed by using RT-PCR. The results showed CCK pDNA was successfully constructed and expressed transiently in COS-7 cells. Green fluorescent protein could be detected in the COS-7 cells transfected with porcine CCK pDNA 24 h post-transfection. At 48th h post-transfection, the number of positive cells was increased significantly and much brighter green fluorescence could be detected.And 72 h post-transfection, the green fluorescence of positive cells became even stronger, while no green fluorescence was detected in the control group. The expression of CCK mRNA in the cells was detectable by using RT-PCR. In COS-7 cells transfected with CCK pDNA a high level of porcine CCK mRNA was detected while no expression of porcine CCKmRNA was found in the cells transfected with null plasmid. It was concluded CCK pDNA was expressed successfully in COS-7 cells,which lays a foundation for further research on the relationship between CCK and tumor.

Construction of recombinant plasmid pIRES2-EGFP/CCK and its expression in vivo and in vitro / 中南大学学报(医学版)

Objective To construct eukaryotic expression plasmid of porcine CCK gene pIRES2-EGFP/CCK and express it in COS-7 cells and hamsters. Methods The aimed segments were obtained from intermediate vector pMD18-T/CCK and were inserted into an eukaryotic expression plasmid pIRES2-EGFP to construct a recombinant expression plasmid pIRES2-EGFP/CCK. The recombinant expression plasmid was transfected into COS-7 cells by liposome-mediated gene transfer method and was observed through fluorescence microscope. The plasmid was injected into the skeletal muscle of hamsters directly to detect the expression of the recombinant plasmid in vivo. Results A recombinant eukaryotic expression plasmid pIRES2-EGFP/CCK was successfully constructed. Green fluorescent protein could be detected in the transfected COS-7 cells 24, 48, and 72 hours after the transfection. On the 4th day postinjection into the skeletal muscle of hamsters, the protein could be detected at the injection site and the fluorescence intensity became much stronger on the 14th day than that on the 4th day. On the 42nd day the protein level increased. The green fluorescence protein was never expressed in the untransfected cells. Conclusion The porcine CCK gene eukaryotic expression plasmid pIRES2-EGFP/CCK is constructed successfully, and is expressed in mammal COS-7 cells and hamsters in vivo. The research paves the way for the cross immunity therapy of hamster pancreatic carcinoma.

Cloning and expression of human DcR3 molecule in COS-7 cells / 第三军医大学学报

Objective To clone ORF of DcR3 gene and insert it into eukaryotic expression vector and express it in COS-7 cells. Methods Encoding sequence of human DcR3 gene was cloned by PCR and sequenced. The sequenced ORF was cloned into eukaryotic expression vector pAAV-IRES-hrGFP to construct recombinant plasmid. COS-7 cells were transfected with recombinant plasmid by lipofectamine2000. Expression of recombinant DcR3 gene was verified by Western blotting and confocal microscopy. Results A 1 000-bp gene segment was obtained by PCR and inserted into pAAV-IRES-hrGFP to construct recombinant plasmid. The gene segment was proved to be encoding sequence of human DcR3 gene by sequencing. DcR3 expression in COS-7 cells was verified by Western blotting and confocal microscopy. Conclusion DcR3 gene was successfully cloned and expressed in COS-7 cells.

Construction of a human Flt3-ligand gene containing eukaryotic expressing vector and its expression in COS-7 cells / 中国免疫学杂志

Objective:To construct an eukaryotic expressing vector pIRES1neo/hFL and express hFL in COS 7 cell.Methods:The cDNA encoding soluble human Flt3 ligand(FL) was obtained by RT PCR from the TF 1 cell lines and was inserted into eukaryotic expressing vector pIRES1neo between EcoR I and BamH I sites after sequencing,and then COS 7 cells were transfected with the recombinant by liposome.The transcription and expression of hFL in the transfected COS 7 cells were assayed by RT PCR,ELISA and the experiment of the human umbilical blood CD34 + cell multiplication,respectively,at 72 hours after transfection.Results:It showed that hFL cDNA cloned in our laboratory was 546 bp in length encoding soluble human FL which was in accordance with the report previously.FL gene was transcripted in transfectants,and FL protein with obvious biological activity was highly expressed with 251 ng/(10 6 cell?d) in the supernatant of the transfectants.Conclusion:Human FL in the recombinant vector is proved to be expressed in COS 7 cells and obvious biological activity of hFL in the supernatant of the transfectants was detected.