Research progress on stable gene transfection methods of Plasmodium falciparum / 中国热带医学

@#Abstract: Transfection of Plasmodium falciparum is helpful to study the function of its genes, such as drug resistance. However, transgenic manipulation has been very challenging, mainly due to the high A/T base sequence structure (A+T content of about 82%) and low transfection efficiency of the Plasmodium genome. Electroporation-based transfection of Plasmodium falciparum has been successfully applied in the study of certain genes, and electroporation by preloading is currently the preferred method for introducing foreign DNA into Plasmodium falciparum. The site-directed editing of Plasmodium genes mostly adopts the method of two-plasmid transfection. It is generally believed that successful transfection of Plasmodium requires a large amount of high-purity plasmid DNA and an accurate transfection system. In addition to the evaluation of the current commonly used electrotransfection methods, this paper also introduces a new transfection method, namely lyse-reseal erythrocytes for transfection (LyRET). This paper also review the role of factors such as plasmid DNA concentration, the use of transfection reagents, the setting of transfection parameters, the addition of fresh red blood cells, and the markers of successful transfection in improving the success rate and efficiency of Plasmodium transfection, in the hope of providing a reference for study in this field.

Stable co-expression of human kappa opioid receptor and PKAcat-EGFP in CHO cells and functional identification / 中国药理学通报

Aim To establish a cell model which stably co-ex-press human kappa opioid receptor (hKOR) and enhanced green fluorescent protein ( EGFP) labeled catalytic domain of cAMP-dependent protein kinase A(PKAcat) fusion protein (PKAcat-EGFP) in Chinese hamster ovary(CHO) cells, laying the foun-dation for the high-throughput screening of hKOR drugs and drug molecular mechanisms in vitro. Methods Hygromycin B resist-ant hKOR recombinant plasmid [ pcDNA3.1/Hygro ( + ) -hKOR] was transfected into CHO cells stably expressing PKA-cat-EGFP by a lipofectin based method. Transfected cells were selected in culture medium containing hygromycin B. The posi-tive clones were selected by PKA redistribution assay. Z’ factor was used for evaluation and validation the reliability of the cell model. PKA redistribution assay and LANCE cAMP 384 Kit were used to test the function of the receptors in selected clone. Results CHO-PKAcat-EGFP/hKOR-13 cell model exhibited stable response in PKA redistribution assay and LANCE cAMP 384 Kit. Treated with 100 nmol·L-1U-50488 for 30 min, the average value of Z’ factor was 0.596, proving the reliability of the cell model. The hKOR expression in cell model remained stable after a few generations. Conclusion The CHO-PKAcat-EGFP/hKOR-13 cell model with stable co-expression of hKOR and PKAcat-EGFP has been successfully established.

Construction of lentiviral vector-mediated Cx32 stably over-expressed Huh7 cell line and its effect on cell proliferation / 中国药理学通报

Aim To construct a lentiviral vector for stable delivery of the connexin32 (Cx32) gene in human hepatocellular carcinoma cell line Huh7,and also to detect its effect on cell proliferation.Methods Human Cx32 gene sequence was obtained by whole gene synthesis and amplified by PCR,and was then inserted into LV5-GFP lentiviral vector to construct the recombinant plasmid LV5-GFP-hCx32.Following identified by restriction endonuclease digestion and DNA sequencing,this plasmid together with lentiviral package plasmid was transfected into 293T cells to produce the lentiviral particles,and the viral titer was assessed under fluorescent microscope.Targeted Huh7 cells were infected with the lentivirus (LV5-hCx32 and LV5-NC),and the infected cells after selection with puromycin were amplified and cultured.The expression and localization of Cx32 were detected by real-time RT-PCR,Western blot and immunofluorescence assay,respectively.The gap junction (GJ) function between adjacent cells was measured by dye transfer assay.The Huh7 cell proliferation capacity was determined by MTT and colony formation assays.Results The results of double enzyme digestion and DNA sequencing proved that the recombinant lentiviral vector LV5-GFP-hCx32 was successfully constructed.After packing in 293T cells,the recombinant lentivirus LV5-GFP-hCx32 with virus drops to 3 × 1011 TU · L-1 was obtained.Huh7 cells transiently infected with the lentivirus LV5-GFP-hCx32 remarkably over-expressed Cx32 at both mRNA and protein levels.Moreover,Cx32 expression was also significantly up-regulated in stably transfected Huh7 cells,and the presence of enhanced functional GJ in intact cells could be detected due to an increased amount of Cx32 protein along the plasma membrane at cell-cell contacts.Compared to LV5-NC group,the proliferation ability in Huh7 cells with recombinant Cx32 declined (P ＜ 0.05).Conclusions The lentiviral vector over-expressing Cx32 gene is successfully constructed,and can stably transfect Huh7 cells to yield sustained over-expression of exogenous Cx32 gene,thus eventually inhibits cell proliferation.

Comparison of hPepT1 transfected MDCK cells to hPepT1 transfected HeLa cells / 中国药理学通报

Aim To screen a more suitable transfection recep-tor,and improve the efficiency of constructing cell lines highly expressing human peptide transporters 1 (hPepT1 ).Methods The recombinant plasmid pcDNA3.1 (+)-hPepT1 was transfect-ed into MDCK cells and HeLa cells by LipofectamineTM 2000 transfection reagent,respectively.The monoclonal cells were se-lected and cultured.Expression of hPepT1 mRNA and protein were determined by qRT-PCR and Western blot,respectively. The uptake capacity of Glysar in transfected cells was examined. Results Compared with wild type cells,the expression of hPepT1 and the uptake of Glysar in transfected MDCK cells and HeLa cells significantly increased (P <0.05).Although the up-take of Glysar in HeLa cells was higher than that of MDCK cells,on the contrary,the expression of hPepT1 and the uptake of Glysar in MDCK-hPepT1 cells was higher than that of HeLa-hPepT1 cells.Conclusion MDCK cells may serve as a more suitable transfected receptor for the construction of a cellular model with high expression of hPepT1 ,which would make the construction of a cell model highly expressing hPepT1 more effi-cient.

Establishment and identification of HEK293 cell lines with stable and high expression of NTCP / 中国药理学通报

Abstrate:Aim To construct HEK293 cell line with stable and high expression of sodium taurocholate cotransporting polypeptide (NTCP ) efficiently and rapidly.Method Vector expressing EGFP-NTCP fusion protein was constructed and verified by DNA sequencing.The pEGFP-NTCP expression vector was transfected into HEK293 cells by FuGENE 6 transfection reagent. The transfected cells with high expression of green fluorescent protein were selected using fluorescence microscope for screening of G418 for 14 days to obtain cell lines stably and highly expressing NTCP.NTCP expression was detected by RT-PCR,qRT-PCR, Western-blot and the uptake experiment of taurocholic acid.Re-sult RT-PCR,qRT-PCR,Western-blot and the uptake experi-ment revealed that compared to the control cells,the expression of NTCP was significantly positive (P<0.01)in stable trans-fected cells showing green fluorescence (P<0.05 ).Conclusion The HEK293 cell line with stable and high expression of NTCP has been established efficiently and rapidly,which provides a cellular model for the study of the mechanism of the uptake of bile acid derivatives.

High-Throughput Assessment of Mitochondrial Fluorescence Labeling at Single-Particle Level / 分析化学

Mitochondria play a central role in the regulation of energy metabolism and signal transduction in eukaryotic cells. Although many fluorescent labeling strategies have been developed for mitochondrial studies, the methods that enable labeling efficiency assessment at the single-mitochondrion level are still lacking. By employing the unique advantages of high sensitivity flow cytometry ( HSFCM ) in the sensitive, rapid, and quantitative multiparameter analysis of individual mitochondria, here we examined the performance of several different mitochondrial labeling strategies from the perspectives of brightness, labeling ratio, and stability. Mitochondria isolated from HeLa cells transfected with pAcGFP1-Mito plasmid upon transient or stable transfections, and mitochondria directly labeled with MitoTracker Green or SYTO 62 were analyzed by a laboratory-built three-channel HSFCM. Upon the quantitative measurement of fluorescence brightness, it was found that the fluorescence intensity of green fluorescent protein ( GFP ) in mitochondria isolated from cells with stable transfection was about 17. 7-fold higher than the transient transfection ones, and was approximately two orders of magnitude brighter than mitochondria labeled with MitoTracker Green. On the other hand, the fluorescence signal of SYTO 62 labeling decreased upon washing, indicating its rapid dissociation rate. The strong fluorescence intensity and good labeling stability make stable transfection an efficient method to label mitochondria. The experimental results demonstrates that HSFCM provides a powerful analytical tool to assess the performance of mitochondrial fluorescence labeling via high throughput single mitochondria analysis.

Construction and functional study of three plasmids including Smad3 WT, Smad3 EPSM and Smad3 3S-A stably transfected HepG2 cell lines / 中国药理学通报

Aim Toconstructthreeplasmidsincluding Smad3 WT,Smad3 EPSM and Smad3 3S-A stable transfection in HepG2 cell lines to investigate phospho-domains of Snad3(pSmad3C or pSmad3L),their pro-tein expression and roles in HepG2 cell proliferation, apoptosisandcellcycle.Methods Threeplasmidsin-cluding Smad3 WT (Carry the wild Smad3 gene ), Smad3 EPSM(Carry the mutated phosphorylation site in linker region of Smad3 gene)and Smad3 3S-A(Car-ry the mutated phosphorylation site in C-terminal of Smad3 gene)were respectively transfected into HepG2 cells by using a liposome transfection reagent.Verifi-cation of positive cells was done by screening with G418 via co-culture.Transfection efficiency was deter-mined by Western blot.Cell proliferation was induced by exogenous TGF-β1 in the respective stably transfect-ed HepG2 cell lines.Cell proliferation was monitored by MTT.Cell cycle and apoptosis were determined by flowcytometry(FCM).Results Therewaselevated protein expression of the respective phospho-domain sites in the stably transfected HepG2 cells for Smad3 WT(C-terminus and Linker),Smad3 EPSM(C-termi-nus)and Smad3 3S-A(Linker),which indicated suc-cessful stable transfection of HepG2 cell lines.The re-sults from MTT experiment showed that TGF-β1 could induce proliferation of HepG2 cells with or without the transfection of Smad3 WT,Smad3 EPSM and Smad3 3S-A plasmids,meanwhile transfected Smad3 EPSM plasmids could significantly inhibit proliferation of HepG2 cells induced by TGF-β1 , and transfected Smad3 3S-A plasmids accelerate proliferation of HepG2 cells induced by TGF-β1 .Cell cycle analysis showed that the G0/G1 phase of HepG2 cells with stable trans-fection of Smad3 EPSM plasmid increased compared with HepG2 cells with or without stable transfection of Smad3 WT plasmid,meanwhile the G2/M phase of HepG2 cells with stable transfection of Smad3 3 S-A plasmid increased.Compared with Smad3 WT trans-fected cells, apoptosis in Smad3 EPSM transfected cells was markedly increased,while that of Smad3 3S-Atransfectedcellsdecreased.Conclusions Thethree plasmids of Smad3 WT,Smad3 EPSM and Smad3 3S-A stably transfected HepG2 cell lines have been suc-cessively constructed.The construction of three plas-mids transfected HepG2 cell lines provides the research foundation for studying medical as well as possible reg-ulatory mechanism of pSmad3 C/pSmad3 L.

Construction of human Ewing sarcoma cell line with knockdown of inhibitor of differentiation 2 gene / 肿瘤研究与临床

Objective To construct short hairpin RNA (shRNA) expression plasmids against the inhibitor of differentiation 2 (Id2) gene and establish a suitable cell model for the role of Id2 in proliferation and differentiation of human Ewing sarcoma cell.Methods Three shRNA sequences targeting Id2 gene were designed and inserted into the pGPU6/GFP/Neo (-shRNA-Id2) expression vectors.The recombinant pGPU6/GFP/Neo-shRNA-Id2 plasmids were introduced into Ewing sarcoma RD-ES cells by liposome-mediated transfection.The knock-down efficiency of Id2 in infected RD-ES cells was verified by Western blot assay.The cell growth and cell cycle changes were evaluated by cell counting and flow cytometry between transfected cells and control cells.Results The Id2 expression decreased 54 ％ and 57 ％,respectively,in RD-ES cell line which were transfected with the shRNA-Id2-543 and shRNA-Id2-593 plasmids compared with the control group cells by Western blot analysis.The cell growth assay demonstrated that the cell number in transfected cells was significantly decreased during 6-7 d compared with the control group (P ＜ 0.05).The cells at the S-phase of cell cycle were increased [(36.60±1.53) ％ and (44.89E2.46) ％ vs (29.73±2.03) ％,P ＜ 0.05],and no significant changes at the G2 phase or even reduction in the transfected cells.Conclusions Id2 stable knock-down cell lines are successfully established.The reduced expression of Id2 is related with decreased cell growth and cell cycle arrest in the S-phase.Id2 maybe plays an important role in proliferation of Ewing sarcoma cell.

The Ku80 inhibition cell model in telomerase-negative tumor cell lines U2OS and its relation to telomere and radiosensitivity / 中华放射医学与防护杂志

Objective To construct the KU80 inhibition cell model by RNAi in U2OS cell and to explore the relationship between the Ku80,telomeres and radiosensitivity in telomerase-negative tumor cells.Methods U2OS cells were transfected with the recombinant plasmids of pshRNA-K80 by the lipofectamine,and the stable transfected cell clones were selected by G418.After the selection,the cells were collected and analyzed by the flow cytometry.RT-PCR and Western blot were used to measure the expression of Ku80 and Real-time PCR was used to detect the length of telomeres.The radiosensitivity of U2OS was determined by clone formation array.Results The transfection efficiency of the positive cell clones detected by the flow cytometry was (83.23 ± 7.63) ％.The inhibition rate of the Ku80 gene transcription in the cell group with recombinant plasmid was(68.09 ± 1.16)％ and the inhibition rate of the Ku80 protein expression in the same group was (11.03 ± 2.45) ％.The results of Real-time PCR showed that the telomere length of the cell group with recombinant plasmid (1.07 ± 0.07) was significantly shorter than that of the control group (4.42 ± 1.30,F =38.58,P ＜ 0.05) and that of the empty plasmid group (4.11 ±0.84,F =38.58,P ＜ 0.05).Compared to the control group,the telomere length of the empty plasmid group did not changed(4.42 ±0.84 vs.4.11 ±0.84).U2OS cells with Ku80 expression suppressed had lower SF2 than that of the control cells (F =1089.61,P ＜0.05),and resulted in the SER of 1.47.Conclusions The Ku80 inhibition cell model in telomerase-negative U2OS cell line is successfully established which has the shorter telomere length,and is more sensitive to radiation.Telomere shortening caused by pshRNA-of Ku80 is likely to be one of the mechanisms of radiosensitization in this kind of cell model.

Establishment of hsa-mir-122 stably transfected-HepG2 cell line and its lipid metabolism characteristics / 第二军医大学学报

Objective: To establish a HepG2 cell line stably overexpressing hsa-mir-122 by transfecting the HepG2 cells with pEZX-hsa-mir-122 vectors,so as to observe the influence of miR-122 on the lipid metabolism in the liver cells. Methods: The constructed pEZX-hsa-mir-122 and pEZX-mir-control plasmids were identified by restriction enzyme digestion and the right clones by sequencing were subjected to sequencing. And the right clones by sequencing were transfected by Lipofectamine™. The transfection efficiency was assessed by green fluorescent protein expression. The stably transfected cell lines were screened by Puromycin. The expression of miR-122 was examined by real-time PCR. The inhibitory function of miR-122 was testified by Western blotting assay. Nile red was used to observe the content of lipid in HepG2 cells stably overexpressing hsa-mir-122. Results: HepG2 cells were successfully transfected with pEZX-hsa-mir-122 and pEZX-mir-control plasmids. The precursor miRNA sequences were integrated into the genome of HepG2 cells stably overexpressing miR-122. Compared with the control HepG2 cells, the HepG2 cells overexpressing miR-122 contained more lipid in the cytoplasm. Conclusion: The miR-122 precursor sequence can intergrate into the genome of HepG2 cells. The increase of miR-122 level in HepG2 cells can result in abnormal metabolism of lipid.

Establishment of Stable High Expression Cell Line with Green Fluorescent Protein and Resistance Genes / 华中科技大学学报（医学）（英德文版）

In order to establish stable high expression cell lines, the eukaryotic expression vector pIRES2EGFP and recombinant plasmid pIRES2EGFP-TIM-3 were transfected into mammalian cells CHO by Lipofectamine. The transfected cells were cultivated under selective growth medium including G418 and green fluorescent protein (GFP) positive cells were sorted by FACS. Simultaneously, growing transfectants were selected only by G418 in the medium. The GFP expression in stably transfected cells was detected by FACS. Under selective growth conditions with G418, the percentage of GFP positive cells was reduced rapidly and GFP induction was low. In contrast, the percentages of GFP positive cells were increased gradually after FACS. By 3 rounds of GFP selection, the stable high expression cell lines were established. Furthermore, using FACS analysis GFP and the target protein TIM-3 co-expression in the stable transfectants cultured in nonselective medium was detected. Theses results demonstrated that the stably transfected cell lines that express high titer of recombinant protein can be simply and fleetly obtained by using GFP and selective growth medium.

Construction of the eukaryotic expression vector of mouse 24p3 gene and its expression in NIH3T3 cell lines / 第三军医大学学报

Objective To construct the eukaryotic expression vector of mouse 24p3 gene and express it in NIH3T3 fibroblast cell line and verify its biological function of delivering iron into cells. Methods 24p3cDNA was cloned by RT-PCR and the eukaryotic expression vector of mouse 24p3 gene was constructed by gene recombination technique and the recombinant plasmid was verified by restriction enzyme digestion analysis and sequenceing, then transfected into NIH3T3 cells using DOTAP transfection reagent. Then the positive clones were selected and amplified. The expression of 24p3 gene in the culture supernatant of positive clones was analyzed by ELISA and Western blotting and its biological activity of delivering iron into cells was tested by atomic absorption spectrometer. Results The eukaryotic expression vector was constructed successfully. The NIH3T3 cells that stably expressed 24p3 were screened out. 24p3/SIP24 protein could express in the culture supernatant of positive clones and deliver iron into NIH3T3 cells. Conclusion The 24p3 gene was expressed successfully in the transfected NIH3T3 cells with good biological activity, which laid the foundation for further studying its biological function and mechanism involved in the iron metabolism.

Establishment of a eukaryotic expressing system for human decay accelerating factor / 中国免疫学杂志

Objective:To construct recombinant expressing vector pcDNA3-DAF and to develop the NIH3T3 cell model expess human complement regulatory protein decay accelerating factor(DAF,CD55)stably after transfected.Methods:Human membrane complement regulatory protein(hCRP) DAF cDNA containing the full-length of encoding region was cloned into expressing vector pcDNA3.After identification by restriction enzyme digestion,PCR and sequencing,the recombinant plasmid was transfected into NIH3T3 cells with calcium phosphate-DNA precipitate method.A stably-transfected cell line was established by G418 selection.Extraneous gene integration was identified by PCR.Expression of DAF at both mRNA and protein levels was analyzed by RT-PCR,Western blot and indirect immunofluorescence microscopy.Results:The eukaryotic expression vector pcDNA3-DAF was successfully constructed and the DAF gene was transfected stably into NIH3T3 cells,a stably-transfected cell line was established and DAF was efficiently expressed on the surface of transfected NIH3T3 cells.Human DAF cDNA was integrated into NIH3T3 pcDNA3-DAF genomic DNA after continuous 30 times passages,indicating that NIH3T3 pcDNA3-DAF was stable cell line.Conclusion:The establishment of the stably-transfected cell line and the expression of the target gene provide a base for further studies on the function of the DAF and the cooperative fashion among different human complement regulatory proteins in alleviating the complement-mediated cytolysis.

Establishment of HEK293 cell line expressing sense and antisense Alu-Sx stably and efficiently / 第三军医大学学报

Objective To establish a HEK293 cell line stably and highly expressing sense and antisense Alu-Sx.Methods According to Alu subfamily Sx sequence,a pair of primers containing the sites for given restrictive endonuclease at both ends were designed and synthesized.PCR of the total DNA extracted from HEK293 cell line was performed,the products of which were cloned into a highly efficient eukaryotic expression vector pcDNA3.1/myc-His A.The recombinants were sequenced and identified by restrictive endonuclease digestion and then transfected into the HEK293 cell line by lipofectamine2000.The stable transfectants were screened by G418.Cell subclones were isolated by gradient dilution.The highly expressing clones were identified by Northern blotting.Results Eukaryotic expressing vectors stably and efficiently expressing sense and antisense Alu-Sx were constructed and cell subclones stably and efficiently expressing sense and antisense Alu-Sx were established.Conclusion Cell subclones stably and efficiently expressing sense and antisense Alu-Sx can used for our further study.

Stable expression of MCHR2 in CHO cell line and analysis of its signal transduction pathways / 中国药理学通报

Aim To construct a eukaryotic expression vector of human MCHR2 and to analyze the stable expression and signal transduction pathways of MCHR2 in CHO cells. Methods The full-length MCHR2 cDNA fragment was amplified by PCR from the human fetal brain cDNA library and inserted into eukaryotic expres-sion vector pcDNA3.1(+), resulted in the recombinant expression vector pcDNA3.1-MCHR2. The recombinant plasmid was confirmed by the restriction enzymatic digestion and DNA sequencing analysis, and then transfected into CHO cells by lipofectamine. A stably-transfected cell line was obtained by the dominant G418 selection, and the expression of the MCHR2 gene on transcription and translation levels were identified by RT-PCR and Western blot. Signal transduction pathways mediated by MCHR2 were analyzed by measurement of intracellular cAMP and calcium. Results The eukaryotic expression vector pcDNA3.1-MCHR2 was successfully constructed and the MCHR2 gene was stably transfected into CHO cells. A stably-transfected cell line was established and the MCHR2 gene was efficiently transcribed and translated. MCH stimulation had no effect on the production of cAMP, however, it could induce a clear and transient increase of intracellular calcium, suggesting that MCHR2 was only coupled to Gq protein. Conclusion The stable expression of MCHR2 and analysis of its signal transduction pathways in CHO cell line provided a solid experimental foundation for further studies on the function of the MCHR2 gene in vitro.

Expression of human IL-24 gene in CHO cells and its anti-tumor effect in vitro / 中国药理学通报

Aim To construct the eukaryotic expression vector of hIL-24 cDNA,and express it in CHO cells and detect its anti-tumor effect of recombinant hIL-24 protein.Methods Constructed pcDNA3-hIL-24 was identified by endonucleases digestion & PCR.The recombinant expression plasmids were transfected into CHO cells,human hIL-24 expressed in CHO cells was detected with RT-PCR.The apoptosis-inducing activities of recombinant protein hIL-24 was tested by MTT assay,Hoechst& FCM assay,and the expression of IL-6 and IFN-? from PBMC induced by rhIL-24 was tested by ELISA.Results The eukaryotic expression vector pcDNA3-hIL-24 was constructed correctly.Stable expression of human IL-24 in CHO cells was identified with RT-PCR.The apoptosis of A549 cells induced by hIL-24 was proved by Hoechst & FCM assay,and the expression of IL-6 and IFN-? from PBMC induced by rhIL-24 was identified with ELISA.Conclusion The successful stable expression & experimental study of apoptosis effect of human IL-24 gene lay the foundation for the further study of molecular mechanism of hIL-24 on anti-tumors and potential application.