A Novel Cre/lox71-Based System for Inducible Expression of Recombinant Proteins and Genome Editing
Ontology highlight
ABSTRACT:
SUBMITTER: Karagyaur M
PROVIDER: S-EPMC9324666 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:Conditional manipulation of gene expression is a key approach to investigating the primary function of a gene in a biological process. While conditional and cell-type-specific overexpression systems exist for plants, there are currently no systems available to disable a gene completely and conditionally. Here, we present a new tool with which target genes can efficiently and conditionally be knocked out by genome editing at any developmental stage. Target genes can also be knocked out in a cell-type-specific manner. Our tool is easy to construct and will be particularly useful for studying genes having null alleles that are non-viable or show pleiotropic developmental defects.
| S-EPMC7611339 | biostudies-literature
Project description:BACKGROUND: Scientific interest in Enterococcus faecalis has increased greatly over recent decades. Some strains are involved in food fermentation and offer health benefits, whereas others are vancomycin-resistant and cause infections that are difficult to treat. The limited availability of vectors able to express cloned genes efficiently in E. faecalis has hindered biotechnological studies on the bacterium's regulatory and pathogenicity-related genes. The agmatine deiminase (AGDI) pathway of E. faecalis, involved in the conversion of agmatine into putrescine, is driven by a response inducer gene aguR. RESULTS: This study describes that the exposure to the induction factor (agmatine) results in the transcription of genes under the control of the aguB promoter, including the aguBDAC operon. A novel E. faecalis expression vector, named pAGEnt, combining the aguR inducer gene and the aguB promoter followed by a cloning site and a stop codon was constructed. pAGEnt was designed for the overexpression and purification of a protein fused to a 10-amino-acid His-tag at the C-terminus. The use of GFP as a reporter of gene expression in E. faecalis revealed that under induction with 60 mM agmatine, fluorescence reached 40 arbitrary units compared to 0 in uninduced cells. CONCLUSION: pAGEnt vector can be used for the overexpression of recombinant proteins under the induction of agmatine in E. faecalis, with a close correlation between agmatine concentration and fluorescence when GFP was used as reporter.
| S-EPMC4265343 | biostudies-literature
Project description:Maladaptive signaling by pro-inflammatory cytokines (PICs), such as TNFα, IL1β and IFNɣ, can activate downstream signaling cascades that are implicated in the development and progression of multiple inflammatory diseases. Despite playing critical roles in pathogenesis, the availability of in vivo models in which to model tissue-specific induction of PICs is limited. To bridge this gap, we have developed a novel multi-gene expression system dubbed Cre-enabled and tetracycline-inducible transgenic system for conditional, tissue-specific expression of pro-inflammatory cytokines (CETI-PIC3). This binary transgenic system permits the stoichiometric co-expression of proteins Tumor necrosis factor a (Tnfa), Interleukin-1 beta (Il1b) and Interferon gamma (Ifng1), and H2B-GFP fluorescent reporter in a dose-dependent manner. Furthermore, cytokine misexpression is enabled only in tissue domains that can be defined by Cre recombinase expression. We have validated this system in zebrafish using an insulin:cre line. In doubly transgenic fish, quantitative real-time polymerase chain reaction demonstrated increased expression levels of tnfa, il1b and ifng1 mRNA. Moreover, specific expression in pancreatic β cells was demonstrated by both Tnfa immunofluorescence and GFP fluorescence. Cytokine-overexpressing islets elicited specific responses: β cells exhibited increased expression of genes associated with reactive oxidative species-mediated stress and endoplasmic reticulum stress, surveilling and infiltrating macrophages were increased, and β cell death was promoted. This powerful and versatile model system can be used for modeling, analysis and therapy development of diseases with an underlying inflammatory etiology.This article has an associated First Person interview with the first author of the paper.
| S-EPMC7328138 | biostudies-literature
Project description:Metal reduction by members of the Geobacteraceae is encoded by multiple gene clusters, and the study of extracellular electron transfer often requires biofilm development on surfaces. Genetic tools that utilize polar antibiotic cassette insertions limit mutant construction and complementation. In addition, unstable plasmids create metabolic burdens that slow growth, and the presence of antibiotics such as kanamycin can interfere with the rate and extent of Geobacter biofilm growth. We report here genetic system improvements for the model anaerobic metal-reducing bacterium Geobacter sulfurreducens. A motile strain of G. sulfurreducens was constructed by precise removal of a transposon interrupting the fgrM flagellar regulator gene using SacB/sucrose counterselection, and Fe(III) citrate reduction was eliminated by deletion of the gene encoding the inner membrane cytochrome imcH. We also show that RK2-based plasmids were maintained in G. sulfurreducens for over 15 generations in the absence of antibiotic selection in contrast to unstable pBBR1 plasmids. Therefore, we engineered a series of new RK2 vectors containing native constitutive Geobacter promoters, and modified one of these promoters for VanR-dependent induction by the small aromatic carboxylic acid vanillate. Inducible plasmids fully complemented ?imcH mutants for Fe(III) reduction, Mn(IV) oxide reduction, and growth on poised electrodes. A real-time, high-throughput Fe(III) citrate reduction assay is described that can screen numerous G. sulfurreducens strain constructs simultaneously and shows the sensitivity of imcH expression by the vanillate system. These tools will enable more sophisticated genetic studies in G. sulfurreducens without polar insertion effects or need for multiple antibiotics.
| S-EPMC4579418 | biostudies-literature
Project description:Acute manipulation of gene and protein function in the brain is essential for understanding the mechanisms of nervous system development, plasticity and information processing. Here we describe a technique based on a destabilized Cre recombinase (DD-Cre) whose activity is controlled by the antibiotic trimethoprim (TMP). We show that DD-Cre triggers rapid TMP-dependent recombination of loxP-flanked ('floxed') alleles in mouse neurons in vivo and validate the use of this system for neurobehavioral research.
| S-EPMC3947879 | biostudies-literature
Project description:We describe the development and application of a novel series of vectors that facilitate CRISPR-Cas9-mediated genome editing in mammalian cells, which we call CRISPR-Bac. CRISPR-Bac leverages the piggyBac transposon to randomly insert CRISPR-Cas9 components into mammalian genomes. In CRISPR-Bac, a single piggyBac cargo vector containing a doxycycline-inducible Cas9 or catalytically dead Cas9 (dCas9) variant and a gene conferring resistance to Hygromycin B is cotransfected with a plasmid expressing the piggyBac transposase. A second cargo vector, expressing a single-guide RNA (sgRNA) of interest, the reverse-tetracycline TransActivator (rtTA), and a gene conferring resistance to G418, is also cotransfected. Subsequent selection on Hygromycin B and G418 generates polyclonal cell populations that stably express Cas9, rtTA, and the sgRNA(s) of interest. We show that CRISPR-Bac can be used to knock down proteins of interest, to create targeted genetic deletions with high efficiency, and to activate or repress transcription of protein-coding genes and an imprinted long noncoding RNA. The ratio of sgRNA-to-Cas9-to-transposase can be adjusted in transfections to alter the average number of cargo insertions into the genome. sgRNAs targeting multiple genes can be inserted in a single transfection. CRISPR-Bac is a versatile platform for genome editing that simplifies the generation of mammalian cells that stably express the CRISPR-Cas9 machinery.
| S-EPMC6633203 | biostudies-literature
Project description:BACKGROUND: After many years of intensive research, it is generally assumed that no universal expression system can exist for high-level production of a given recombinant protein. Among the different expression systems, the inducible systems are the most popular for their tight regulation. However, induction is in many cases less favorable due to the high cost and/or toxicity of inducers, incompatibilities with industrial scale-up or detrimental growth conditions. Expression systems using autoinduction (or self-induction) prove to be extremely versatile allowing growth and induction of recombinant proteins without the need to monitor cell density or add inducer. Unfortunately, almost all the actual auto inducible expression systems need endogenous or induced metabolic changes during the growth to trigger induction, both frequently linked to detrimental condition to cell growth. In this context, we use a simple modular approach for a cell density-based genetic regulation in order to assemble an autoinducible recombinant protein expression system in E. coli. RESULT: The newly designed pLAI expression system places the expression of recombinant proteins in Escherichia coli under control of the regulatory genes of the lux regulon of Vibrio fischeri's Quorum Sensing (QS) system.The pLAI system allows a tight regulation of the recombinant gene allowing a negligible basal expression and expression only at high cell density. Sequence optimization of regulative genes of QS of V. fischeri for expression in E. coli upgraded the system to high level expression. Moreover, partition of regulative genes between the plasmid and the host genome and introduction of a molecular safety lock permitted tighter control of gene expression. CONCLUSION: Coupling gene expression to cell density using cell-to-cell communication provides a promising approach for recombinant protein production. The system allows the control of expression of the target recombinant gene independently from external inducers or drastic changes in metabolic conditions and enabling tight regulation of expression.
| S-EPMC3274441 | biostudies-literature
Project description:We have developed a fast and accurate method to engineer the Bacillus subtilis genome that involves fusing by PCR two flanking homology regions with an antibiotic resistance gene cassette bordered by two mutant lox sites (lox71 and lox66). The resulting PCR products were used directly to transform B. subtilis, and then transient Cre recombinase expression in the transformants was used to recombine lox71 and lox66 into a double-mutant lox72 site, thereby excising the marker gene. The mutation process could also be accomplished in 2 days by using a strain containing a cre isopropyl-beta-d-thiogalactopyranoside (IPTG)-inducible expression cassette in the chromosome as the recipient or using the lox site-flanked cassette containing both the cre IPTG-inducible expression cassette and resistance marker. The in vivo recombination efficiencies of different lox pairs were compared; the lox72 site that remains in the chromosome after Cre recombination had a low affinity for Cre and did not interfere with subsequent rounds of Cre/lox mutagenesis. We used this method to inactivate a specific gene, to delete a long fragment, to realize the in-frame deletion of a target gene, to introduce a gene of interest, and to carry out multiple manipulations in the same background. Furthermore, it should also be applicable to large genome rearrangement.
| S-EPMC2546623 | biostudies-literature
Project description:The current standard for Bacillus anthracis vaccination is the Anthrax Vaccine Adsorbed (AVA, BioThrax). While effective, the licensed vaccine schedule requires five intramuscular injections in the priming series and yearly boosters to sustain protection. One potential approach to maintain or improve the protection afforded by an anthrax vaccine, but requiring fewer doses, is through the use of purified proteins to enhance an antibody response, which could be used on their own or in combination with the current vaccine. This study describes a novel, high-throughput system to amplify and clone every gene in the B. anthracis pXO1 and pXO2 virulence plasmids. We attempted to express each cloned gene in Escherichia coli, and obtained full-length expression of 57% of the proteins. Expressed proteins were then used to identify immunogens using serum from three different mammalian infection models: Dutch-belted rabbits, BALB/c mice, and rhesus macaque monkeys. Ten proteins were detected by antibodies in all of these models, eight of which have not been identified as immunoreactive in other studies to date. Serum was also collected from humans who had received the AVA vaccine, and similar screens showed that antigens that were detected in the infection models were not present in the serum of vaccinated humans, suggesting that antibodies elicited by the current AVA vaccine do not react with the immunoreactive proteins identified in this study. These results will contribute to the future selection of targets in antigenicity and protection studies as one or more of these proteins may prove to be worthy of inclusion in future vaccine preparations.
| S-EPMC3779308 | biostudies-literature
Project description:BackgroundThe growing need for functional studies of genes has set the stage for the development of versatile tools for genetic manipulations.ResultsAiming to provide tools for high throughput analysis of gene functions, we have developed a modified short hairpin RNA (shRNA) and gene expression system based on Gateway Technology. The system contains a series of entry and destination vectors that enables easy transfer of shRNA or cDNA into lentiviral expression systems with a variety of selection or marker genes (i.e. puromycin, hygromycin, green fluorescent protein-EGFP, yellow fluorescent protein-YFP and red fluorescent protein-dsRed2). Our shRNA entry vector pENTR.hU6.hH1 containing two tandem human shRNA expression promoters, H1 and U6, was capable of co-expressing two shRNA sequences simultaneously. The entry vector for gene overexpression, pENTR.CMV.ON was constructed to contain CMV promoter with a multiple cloning site flanked by loxP sites allowing for subsequent Cre/lox recombination. Both shRNA and cDNA expression vectors also contained attL sites necessary for recombination with attR sites in our destination expression vectors. As proof of principle we demonstrate the functionality and efficiency of this system by testing expression of several cDNA and shRNA sequences in a number of cell lines.ConclusionOur system is a valuable addition to already existing library of Gateway based vectors and can be an essential tool for many aspects of gene functional studies.
| S-EPMC3070635 | biostudies-literature