In vitro expression of a mouse tissue specific glutathione-peroxidase-like protein lacking the selenocysteine can protect stably transfected mammalian cells against oxidative damage

1996 ◽  
Vol 74 (1) ◽  
pp. 125-131 ◽  
Author(s):  
Patrick Vernet ◽  
Nicole Rigaudiére ◽  
Norbert Ghyselinck ◽  
Jean Pierre Dufaure ◽  
Joël R. Drevet
Keyword(s):  
Glutathione Peroxidase ◽  
Mammalian Cells ◽  
Expression System ◽  
Complete Sequence ◽  
Protein Domain ◽  
Mouse Tissue ◽  
Reading Frame ◽  
Mammalian Expression ◽  
Mouse Epididymis

The complete sequence of the mouse epididymal protein (MEP24) was cloned. It contains a 663 bp open-reading frame that, after conceptual translation, shows extensive identity with proteins belonging to the glutathione peroxidase (GPX) family. However, a major difference between GPX5 (MEP24) and other known GPXs concerns a protein domain known to be critical for GPX function. To find out what could be the physiological function of such a protein in the mouse epididymis, we have used a mammalian expression system to overexpress the GPX5 protein. Cells constitutively expressing the GPX5 protein were generated and assayed for their ability to metabolize regular substrates of GPX enzymes. Data presented here show that the GPX5-expressing cells can metabolize hydrogen peroxide in a manner that is consistent with a peroxidase activity. However, the substrate preference of the GPX5-expressing cells and their apparent insensitivity to a regular inhibitor of GPX enzymes suggest that the GPX5 protein belongs to a particular class of GPX proteins. Involvement of this protein in the physiology of the mouse epididymis is discussed.Key words: glutathione peroxidase (GPX), mouse epididymis, MEP24, GPX5 cDNA, selenocysteine, GPX5 polyclonal antibody, spermatozoa, CHO-KI cells.

scholarly journals Differences in the expression of the hepatitis C virus core+1 open reading frame between a nuclear and a cytoplasmic expression system

2008 ◽  
Vol 89 (1) ◽  
pp. 222-231 ◽  
Author(s):  
Niki Vassilaki ◽  
Katerina I. Kalliampakou ◽  
Penelope Mavromara
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Mammalian Cells ◽  
Expression System ◽  
Open Reading Frame ◽  
Reading Frame ◽  
Transcription System ◽  
The Core ◽  
Internal Core

The hepatitis C virus (HCV) genome possesses an open reading frame (ORF) overlapping the core gene at +1 nucleotide (core+1 ORF). Initial in vitro studies suggested that the core+1 ORF is translated by a ribosomal −2/+1 frameshift mechanism during elongation of the viral polyprotein. Recent studies, however, based on transfection of mammalian cells with reporter constructs have shown that translation of the core+1 ORF is mediated from internal core+1 codons. To resolve the apparent discrepancies associated with the mechanism of core+1 translation, we examined the expression of the HCV-1 and HCV-1a (H) core+1 ORF in a cytoplasmic transcription system based on Huh-7/T7 cells that constitutively synthesize the T7 RNA polymerase in comparison to that in Huh-7 cells. We showed that the efficiency of both the −2/+1 and −1/+2 frameshift events operating at the HCV-1 core codons 8–11 is significantly enhanced in the Huh-7/T7 cytoplasmic transcription system and is dependent on the presence of the consecutive adenine (A) residues within core codons 8–11. In contrast, internal translation initiation at core+1 codons 85/87 occurs in both the nuclear and cytoplasmic transcription systems and is not repressed by the ribosomal frameshifting event. Finally, although core+1 codons 85/87 is the most efficient site for internal initiation of core+1 translation, it may not be unique, as additional internal core+1 codon(s) appear to drive translation at low levels.

scholarly journals Development and Application of TK6-derived Cells Expressing Human Cytochrome P450s for Genotoxicity Testing

2020 ◽  
Vol 175 (2) ◽  
pp. 251-265 ◽  
Author(s):  
Xilin Li ◽  
Si Chen ◽  
Xiaoqing Guo ◽  
Qiangen Wu ◽  
Ji-Eun Seo ◽  
...  
Keyword(s):  
Cell Lines ◽  
Mammalian Cells ◽  
Expression System ◽  
Cytochrome P450s ◽  
Mass Spectrometry Analysis ◽  
Established Cell Line ◽  
Micronucleus Formation ◽  
Tk6 Cells ◽  
Genotoxicity Testing

Abstract Metabolism plays a key role in chemical genotoxicity; however, most mammalian cells used for in vitro genotoxicity testing lack effective metabolizing enzymes. We recently developed a battery of TK6-derived cell lines that individually overexpress 1 of 8 cytochrome P450s (CYP1A1, 1A2, 1B1, 2A6, 2B6, 2C9, 2C19, and 3A4) using a lentiviral expression system. The increased expression and metabolic function of each individual CYP in each established cell line were confirmed using real-time PCR, Western blotting, and mass spectrometry analysis; the parental TK6 cells and empty vector (EV) transduced cells had negligible CYP levels. Subsequently, we evaluated these cell lines using 2 prototypical polyaromatic hydrocarbon mutagens, 7,12-dimethylbenz[a]anthracene (DMBA) and benzo[a]pyrene (B[a]P), that require metabolic activation to exert their genotoxicity. DMBA-induced cytotoxicity, phosphorylation of histone H2A.X, and micronucleus formation were significantly increased in TK6 cells with CYP1A1, 1B1, 2B6, and 2C19 expression as compared with EV controls. B[a]P significantly increased cytotoxicity, DNA damage, and chromosomal damage in TK6 cells overexpressing CYP1A1 and 1B1 when compared with EV controls. B[a]P also induced micronucleus formation in TK6 cells expressing CYP1A2. These results suggest that our CYP-expressing TK6 cell system can be used to detect the genotoxicity of compounds requiring metabolic transformation.

Expression and processing of the canine calicivirus capsid precursor

Microbiology ◽  
2000 ◽  
Vol 81 (1) ◽  
pp. 195-199 ◽  
Author(s):  
Yuichi Matsuura ◽  
Yukinobu Tohya ◽  
Mihoko Onuma ◽  
Frank Roerink ◽  
Masami Mochizuki ◽  
...  
Keyword(s):  
Capsid Protein ◽  
Mammalian Cells ◽  
Expression System ◽  
Immunoblot Analysis ◽  
Site Directed Mutagenesis ◽  
Feline Calicivirus ◽  
Putative Cleavage Site ◽  
Mammalian Expression ◽  
Capsid Precursor ◽  
Infected Cells

The ORF2 product of canine calicivirus (CaCV) was identified and its processing in mammalian cells was analysed. Immunoblot analysis revealed the presence of the 75 kDa capsid precursor in addition to a 57 kDa capsid protein and a 22 kDa N-terminal polypeptide in CaCV-infected cells treated at an elevated temperature. When the CaCV ORF2 was expressed in a transient mammalian expression system, only the 75 kDa precursor was detected in immunoblot analysis, suggesting that no post-translational processing occurred in this system. However, the precursor was processed to a 57 kDa protein and a 22 kDa polypeptide by the proteinase of feline calicivirus (FCV) when this was co-expressed with ORF2. Processing was blocked by site-directed mutagenesis of the putative cleavage site in the capsid precursor. The results indicate that the proteinase of FCV can cleave the capsid precursor of CaCV to produce the mature capsid protein and that CaCV may have a similar proteinase.

Rhogtpase RAC2 Is Required for In Vivo Transformation Activity by P210 Bcr-Abl Fusion Oncogene.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 717-717
Author(s):  
Nithya Krishnan ◽  
Jeff R. Bailey ◽  
Victoria Summey-Harner ◽  
Claudio Brunstein ◽  
Catherine M. Verfaillie ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Philadelphia Chromosome ◽  
Protein Domain ◽  
Myelogenous Leukemia ◽  
Wild Type ◽  
Hematopoietic Stem ◽  
Cell Functions ◽  
Empty Vector

Abstract Bcr-Abl, the translocation product of the Philadelphia chromosome implicated in human chronic myelogenous leukemia (CML), is a kinase affecting hematopoietic stem cell (HSC) behavior with respect to proliferation, apoptosis, adhesion and migration. Rho GTPases, particularly the Rac subfamily, have been shown to regulate these same cell functions in normal HSC and also regulate gene expression in many mammalian cells. BCR contains a “GTPase-activating protein” domain and a guanine nucleotide exchange domain, the latter or which is preserved in p210 Bcr-Abl. Since HSC functions regulated by Bcr-Abl and Rac are similar, we studied the potential involvement of Rac activation in Bcr-Abl signaling cascade. Human CML samples demonstrate baseline activation of Rac proteins that is reversed by in vitro treatment with STI571. To study the specific involvement of Rac2, we used a gene targeted mouse model with Rac2 null bone marrow. Using retovirus-mediated gene transfer, we introduced p210 Bcr-Abl in the MSCV vector into wild-type or Rac2−/− HSC/P and studied the behavior of these cells in vitro and in vivo. Irradiated recipient mice injected with LDBM cells transduced with p210 developed a uniformly fatal myeloproliferative syndrome (Median survival: 45 days, N=12), while mice injected with p210 transduced Rac2−/− LDBM cells (N=12, 2 independent exp.) had 100% survival and no development of leukocytosis, splenomegaly or organ infiltration of hematopoietic cells. These data suggest that Rac GTPases are critical for the transformation of HSC by Bcr-Abl and provide an additional therapeutic target for intervention in CML. WILD TYPE Rac 2 −/− Empty Vector MSCV-p210 Empty vector MSCV-p210 *p < 0.01 vs WT-MIEG3, **p< 0.01 vs WT-p210 bcr-abl. Proliferation (CPM) Medium 562 ± 278 16,207± 1605* 819.7 ± 363 3,135.5 ± 498** SCF (100ng/ml) 856 ± 187 23,226 ± 2203* 853.7 ± 524 3,756.8 ± 207** Cytokines (SCF, GCSF, MGDF) 8011± 1412 42,711± 13393* 4833 ±1019 3,614.5 ± 1982** Migration (%) Fibronectin 7 ± 0.4 38 ± 1.9* 0.4 ± 0.0 0.8 ± 0.1** SDF-1α 30 ±2.8 13 ±1.1* 0.5 ± 0.0 0.6 ± 0.0** Adhesion (% ) Fibronectin 76± 2.9 40 ±3* 4 ±0.4 10 ±0.1 **

scholarly journals Firefly luciferase gene: structure and expression in mammalian cells.

1987 ◽  
Vol 7 (2) ◽  
pp. 725-737 ◽  
Author(s):  
J R de Wet ◽  
K V Wood ◽  
M DeLuca ◽  
D R Helinski ◽  
S Subramani
Keyword(s):  
Mammalian Cells ◽  
Firefly Luciferase ◽  
Full Length ◽  
Expression Vectors ◽  
Luciferase Expression ◽  
Luciferase Gene ◽  
S1 Nuclease ◽  
Reading Frame ◽  
Mammalian Expression ◽  
Firefly Luciferase Gene

The nucleotide sequence of the luciferase gene from the firefly Photinus pyralis was determined from the analysis of cDNA and genomic clones. The gene contains six introns, all less than 60 bases in length. The 5' end of the luciferase mRNA was determined by both S1 nuclease analysis and primer extension. Although the luciferase cDNA clone lacked the six N-terminal codons of the open reading frame, we were able to reconstruct the equivalent of a full-length cDNA using the genomic clone as a source of the missing 5' sequence. The full-length, intronless luciferase gene was inserted into mammalian expression vectors and introduced into monkey (CV-1) cells in which enzymatically active firefly luciferase was transiently expressed. In addition, cell lines stably expressing firefly luciferase were isolated. Deleting a portion of the 5'-untranslated region of the luciferase gene removed an upstream initiation (AUG) codon and resulted in a twofold increase in the level of luciferase expression. The ability of the full-length luciferase gene to activate cryptic or enhancerless promoters was also greatly reduced or eliminated by this 5' deletion. Assaying the expression of luciferase provides a rapid and inexpensive method for monitoring promoter activity. Depending on the instrumentation employed to detect luciferase activity, we estimate this assay to be from 30- to 1,000-fold more sensitive than assaying chloramphenicol acetyltransferase expression.

scholarly journals EKPRESI ANTIGEN Ag85B DARI Mycobacterium tuberculosis PADA GALUR SEL MAMALIA

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Sabar Pambudi ◽  
Tika Widayanti ◽  
Nadya Stephanie
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Recombinant Protein ◽  
Western Blot ◽  
Mammalian Cell ◽  
Mammalian Cells ◽  
Culture Media ◽  
Mammalian Cell Culture ◽  
Expression System ◽  
Major Health Problem ◽  
Mammalian Expression

Expression of Mycobacterium tuberculosis Ag85B Antigen in Mammalian Cell CultureTuberculosis (TB) continues to be a major health problem worldwide, affecting millions of people each year. The only vaccine approved for the prevention of TB is Bacillus Calmette-Guérin (BCG). However, one of the limitations of BCG is that its preventive effect against pulmonary TB varies from person to person. Therefore, there arises a need for a new TB vaccine to replace BCG. This study aims to obtain the Ag85B recombinant protein which has characteristics similar to the native Ag85B antigen from Mycobacterium tuberculosis. In this study, we cloned and expressed recombinant Ag85B in mammalian cell culture. In the initial step, we cloned synthetic Ag85B into mammalian expression vector pFLAG-CMV4 and expressed the gene in CHO-K1 cells. Interestingly, a specific band around 30 kDa was observed in the culture media of transfected cells by Western blot analysis. The results from our research showed the potency of mammalian expression system to produce recombinant protein Ag85B for new TB vaccine candidate.Keywords: Ag85B, mammalian cells, tuberculosis, vaccine, expression ABSTRAKTuberkulosis (TB) terus menjadi salah satu masalah kesehatan dunia yang mempengaruhi jutaan manusia setiap tahun. Satu-satunya vaksin untuk TB yang ada adalah Bacillus Calmette-Guérin (BCG). Namun demikian, vaksin BCG ini memiliki kelemahan berupa terjadi efek preventif yang bervariasi dari satu individu terhadap individu lainnya.  Oleh sebab itu diperlukan pengembangan vaksin TB yang dapat menggantikan vaksin BCG yang sudah ada. Penelitian ini bertujuan memperoleh protein rekombinan Ag85B yang memiliki karakteristik mirip dengan antigen Ag85B native dari Mycobacterium tuberculosis. Pada penelitian ini, telah dilakukan kegiatan pengklonaan dan ekspresi gen Ag85B pada galur sel mamalia.  Pada tahap awal dilakukan pengklonaan gen sintesis Ag85B ke dalam plasmid pada sel mamalia pFLAG-CMV4 dan diekspresikan gennya pada sel CHO-K1. Hasil analisis Western blot menunjukan tersekresinya gen target berukuran 30 kDa pada media kultur dari sel mamalia yang ditransfeksi. Hasil dari penelitian ini menunjukkan potensi dari sistem ekpresi untuk protein rekombinan Ag85B pada galur sel mamalia sebagai kandidat vaksin TB yang baru.

scholarly journals Using Plasmodium knowlesi as a model for screening Plasmodium vivax blood-stage malaria vaccine targets reveals new candidates

2021 ◽  
Vol 17 (7) ◽  
pp. e1008864
Author(s):  
Duncan N. Ndegwa ◽  
Prasun Kundu ◽  
Jessica B. Hostetler ◽  
Alejandro Marin-Menendez ◽  
Theo Sanderson ◽  
...  
Keyword(s):  
Plasmodium Vivax ◽  
Culture System ◽  
Vaccine Development ◽  
Expression System ◽  
Critical Role ◽  
Blood Stage ◽  
Effective Vaccine ◽  
Mammalian Expression ◽  
Close Phylogenetic Relationship

Plasmodium vivax is responsible for the majority of malaria cases outside Africa. Unlike P. falciparum, the P. vivax life-cycle includes a dormant liver stage, the hypnozoite, which can cause infection in the absence of mosquito transmission. An effective vaccine against P. vivax blood stages would limit symptoms and pathology from such recurrent infections, and therefore could play a critical role in the control of this species. Vaccine development in P. vivax, however, lags considerably behind P. falciparum, which has many identified targets with several having transitioned to Phase II testing. By contrast only one P. vivax blood-stage vaccine candidate based on the Duffy Binding Protein (PvDBP), has reached Phase Ia, in large part because the lack of a continuous in vitro culture system for P. vivax limits systematic screening of new candidates. We used the close phylogenetic relationship between P. vivax and P. knowlesi, for which an in vitro culture system in human erythrocytes exists, to test the scalability of systematic reverse vaccinology to identify and prioritise P. vivax blood-stage targets. A panel of P. vivax proteins predicted to function in erythrocyte invasion were expressed as full-length recombinant ectodomains in a mammalian expression system. Eight of these antigens were used to generate polyclonal antibodies, which were screened for their ability to recognize orthologous proteins in P. knowlesi. These antibodies were then tested for inhibition of growth and invasion of both wild type P. knowlesi and chimeric P. knowlesi lines modified using CRISPR/Cas9 to exchange P. knowlesi genes with their P. vivax orthologues. Candidates that induced antibodies that inhibited invasion to a similar level as PvDBP were identified, confirming the utility of P. knowlesi as a model for P. vivax vaccine development and prioritizing antigens for further follow up.

SUSTAINED EXPRESSION OF FULL LENGTH AND VARIANT RECOMBINANT FACTOR VIII IN GENETICALLY ENGINEERED CELLS

1987 ◽  
Author(s):  
Nava Sarver ◽  
George A Ricca
Keyword(s):  
Factor Viii ◽  
Recombinant Dna ◽  
Expression System ◽  
Genetically Engineered ◽  
Full Length ◽  
Cdna Insert ◽  
Mammalian Expression ◽  
Coagulant Activity ◽  
Recombinant Fviii

A major effort is presently underway to provide factor VIII (FVIII) in a form free of viral pathogens via a recombinant DNA approach. We have constructed two chimeric FVIII cDNA vectors based on the bovine papillomavirus mammalian expression system. The first vector (FVIII) contained a full length FVIII cDNA; the second vector (AFVIII) contained a cDNA insert with an extensive deletion, corresponding to amino acid residues 747 to 1560 in the region encoding the "B" domain. This internal region is removed during activation of the parental FVIII molecule and is believed not to be required for coagulant activity. We have found that recombinant FVIII produced by stable cell lines harboring either the full length or the variant FVIII was capable of restoring coagulant activity to FVIII deficient plasma in. vitro. This expressed activity was neutralized by anti-FVIII antibodies. Similar to observations with FVIII derived from human plasma, the two recombinant FVIII forms were (i) inactivated by the chelating agent EDTA, (ii) demonstrated a biphasic response of an initial activation followed by a decay in activity when treated with thrombin, and (iii) presented the expected peptide banding pattern by western blot analyses. A higher percentage of ΔFVIII transformants were isolated expressing coagulant activity compared to transformants harboring the complete FVIII cDNA. Among the positive transformants isolated, those harboring ΔFVIII produced higher levels of coagulant activity than their full length counterparts. Comparable steady state levels of FVIII specific transcripts were detected in FVIII and ΔFVIII transformants indicating that the difference in expression levels is due to a post transcriptional event(s). Our study demonstrates the efficacy of a full length and an abridged recombinant FVIII produced by stably transformed cells in correcting coagulation deficiency in. vitro. It further suggests the potential usefulness of other molecular variants for efficient expression in genetically engineered cells.

scholarly journals Heterologous expression and cell membrane localization of dinoflagellate rhodopsins in mammalian cells

2020 ◽  
Author(s):  
Minglei Ma ◽  
Xinguo Shi ◽  
Senjie Lin
Keyword(s):  
Cell Membrane ◽  
Proton Pump ◽  
Mammalian Cells ◽  
Expression System ◽  
Type I ◽  
Type Ii ◽  
Mammalian Expression ◽  
Domains Of Life ◽  
Targeting Signal ◽  
Large Groups

AbstractRhodopsins are now found in all domains of life, and are classified into two large groups: type II, found in animals and type I found in microbes including Bacteria, Archaea, and Eukarya. While type II rhodopsin functions in many photodependent signaling processes including vision, type I among others contains rhodopsins that function as a light-driven proton pump to convert light into ATP as in proteobacteria (named proteorhodopsin). Proteorhodopsin homologs have been documented in dinoflagellates, but their subcellular localizations and functions are still poorly understood. Even though sequence analyses suggest that it is a membrane protein, experimental evidence that dinoflagellate rhodopsins are localized on the plasma membrane or endomembranes is still lacking. As no robust dinoflagellate gene transformation tool is available, we used HEK 293T cells to construct a mammalian expression system for two dinoflagellate rhodopsin genes. The success of expressing these genes in the system shows that this mammalian cell type is suitable for expressing dinoflagellate genes. Immunofluorescence of the expressed protein locates these dinoflagellate rhodopsins on the cell membrane. This result indicates that the protein codons and membrane targeting signal of the dinoflagellate genes are compatible with the mammalian cells, and the proteins’ subcellular localization is consistent with proton pump rhodopsins.

Firefly luciferase gene: structure and expression in mammalian cells

1987 ◽  
Vol 7 (2) ◽  
pp. 725-737 ◽  
Author(s):  
J R de Wet ◽  
K V Wood ◽  
M DeLuca ◽  
D R Helinski ◽  
S Subramani
Keyword(s):  
Mammalian Cells ◽  
Firefly Luciferase ◽  
Full Length ◽  
Expression Vectors ◽  
Luciferase Expression ◽  
Luciferase Gene ◽  
S1 Nuclease ◽  
Reading Frame ◽  
Mammalian Expression ◽  
Firefly Luciferase Gene

The nucleotide sequence of the luciferase gene from the firefly Photinus pyralis was determined from the analysis of cDNA and genomic clones. The gene contains six introns, all less than 60 bases in length. The 5' end of the luciferase mRNA was determined by both S1 nuclease analysis and primer extension. Although the luciferase cDNA clone lacked the six N-terminal codons of the open reading frame, we were able to reconstruct the equivalent of a full-length cDNA using the genomic clone as a source of the missing 5' sequence. The full-length, intronless luciferase gene was inserted into mammalian expression vectors and introduced into monkey (CV-1) cells in which enzymatically active firefly luciferase was transiently expressed. In addition, cell lines stably expressing firefly luciferase were isolated. Deleting a portion of the 5'-untranslated region of the luciferase gene removed an upstream initiation (AUG) codon and resulted in a twofold increase in the level of luciferase expression. The ability of the full-length luciferase gene to activate cryptic or enhancerless promoters was also greatly reduced or eliminated by this 5' deletion. Assaying the expression of luciferase provides a rapid and inexpensive method for monitoring promoter activity. Depending on the instrumentation employed to detect luciferase activity, we estimate this assay to be from 30- to 1,000-fold more sensitive than assaying chloramphenicol acetyltransferase expression.

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