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1
BRATSLAVETS, Bogdan. "RESTORATION OF PARTS OF AGRICULTURAL MACHINES WITH ZINC-BASED GALVANIC COATINGS." Herald of Khmelnytskyi National University. Technical sciences 309, no. 3 (2022): 82–84. http://dx.doi.org/10.31891/2307-5732-2022-309-3-82-84.
Texte intégralRésumé :
Galvanizing is most often used to protect against corrosion. In repair production zinc coverings are used for protection against corrosion of fastening details and restoration of landing surfaces of lightly loaded details. Electroplating is the process of applying metal to the surface of parts by crystallizing it from an aqueous solution of the corresponding salts (electrolyte) when a direct current passes through them. An electrical circuit is closed by an electrolyte between two conductors called electrodes. The electrode to which the conductor of the external circuit with a plus is attached is called the anode, and with a minus – the cathode. The repaired part, on which the metal is built up, serves as the cathode, and the anode – plates, copper, lead, zinc, cadmium and other metals. In electrolysis, soluble and insoluble anodes are used. In practice, soluble lead is most often used, and insoluble lead is used only for chromium plating. The preparation of the surface of the part before coating (machining, degreasing, digestion) is important for the quality of the coating. The paper identifies the advantages and disadvantages of the method of updating parts of agricultural machinery with galvinic coatings based on zinc. This makes it possible to analyze the results of experiments and evaluate the effectiveness of using this method of restoring parts. The article presents the technological process of restoration of parts by galvinic galvanizing using an activator and the results of experiments using graphs of the dependence of the rate of coating on the current density and the speed of the activator. Determine whether the use of an experimental activator will increase the speed and quality of coating on parts.
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Mostoni, Milana, Credico, D’Arienzo, and Scotti. "Zinc-Based Curing Activators: New Trends for Reducing Zinc Content in Rubber Vulcanization Process." Catalysts 9, no. 8 (2019): 664. http://dx.doi.org/10.3390/catal9080664.
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The efficiency of sulfur vulcanization reaction in rubber industry is generally improved thanks to the combined use of accelerators (as sulphenamides), activators (inorganic oxides), and co-activators (fatty acids). The interaction among these species is responsible for the formation of intermediate metal complexes, which are able to increase the reactivity of sulfur towards the polymer and to promote the chemical cross-links between the rubber chains. The high number of species and reactions that are involved contemporarily in the process hinders the complete understanding of its mechanism despite the long history of vulcanization. In this process, ZnO is considered to be the most efficient and major employed activator and zinc-based complexes that formed during the first steps of the reaction are recognized to play a main role in determining both the kinetic and the nature of the cross-linked products. However, the low affinity of ZnO towards the rubber entails its high consumption (3–5 parts per hundred, phr) to achieve a good distribution in the matrix, leading to a possible zinc leaching in the environment during the life cycle of rubber products (i.e., tires). Thanks to the recent recognition of ZnO ecotoxicity, especially towards the aquatic environment, these aspects gain a critical importance in view of the urgent need to reduce or possibly substitute the ZnO employed in rubber vulcanization. In this review, the reactivity of ZnO as curing activator and its role in the vulcanization mechanism are highlighted and deeply discussed. A complete overview of the recent strategies that have been proposed in the literature to improve the vulcanization efficiency by reducing the amount of zinc that is used in the process is also reported.
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Heideman, Geert, Jacques W. M. Noordermeer, Rabin N. Datta, and Ben van Baarle. "Zinc Loaded Clay as Activator in Sulfur Vulcanization: A New Route for Zinc Oxide Reduction in Rubber Compounds." Rubber Chemistry and Technology 77, no. 2 (2004): 336–55. http://dx.doi.org/10.5254/1.3547827.
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Abstract Concern about the release of eco-toxic zinc species from rubbers into the environment leads to an increasing interest in potential substitutes. Although alternative metal oxides and zinc compounds as activators for sulfur vulcanization have been studied thoroughly, at present no viable alternative has been found to eliminate ZnO completely from rubber compounds, without significantly jeopardizing processing as well as performance characteristics. In this paper, the application of a new activator for sulfur vulcanization will be discussed. This activator is developed based on the assumption that an increase in the availability of Zn2+-ions could lead to a considerable reduction of ZnO in rubber compounds. Montmorillonite clay was used as carrier material and loaded with Zn2+-ions via an ion-exchange process. Application in a wide range of natural and synthetic rubbers has been explored. Results clearly demonstrate that this Zn-Clay can substitute conventional ZnO, retaining the curing and physical properties of the rubber products but reducing the zinc concentration with a factor 10 to 20. Model Compound Vulcanization studies have been used to gain an insight into the mechanism of this activator. It can be concluded that systems with Zn2+-ions on a support represent a new and novel route to reduce the zinc level, and therefore to minimize its environmental impact significantly.
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Javadi, Seyyed Mohammad. "Applications of ZnO and MgO Nanoparticles in Reducing Zinc Pollution Level in Rubber Manufacturing Processes: A Review." Current Biochemical Engineering 6, no. 2 (2020): 103–7. http://dx.doi.org/10.2174/2212711906666200224105931.
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Background: Rubber vulcanization is a consolidated chemical process to enhance the mechanical properties of the polymeric material by sulfur crosslinking of the polymer chains, such as rubber. Vulcanization Activators are important rubber processing additives that activate sulfur cure and improve the efficiency of sulfur-based cure systems. The most common activator is zinc fatty acid ester that is often formed in-situ by the reaction of fatty acid with zinc oxide. Although zinc is one of the less harmful heavy metals, according to European Council Directive 2004/73/EC, the reduction of zinc level in the environment has become an important task because of its toxic effect on aquatic organisms. : The current study reviews the research achievements in the field of reducing the consumption of micronutrients of ZnO particles based on the use of nanoparticles instead of them in the polymer industry. Among the proposed methods, due to the less environmental effects of magnesium oxide, the use of MgO nanoparticles instead of zinc oxide has also achieved good results. Objective: The aim of this paper is considering suggested different methods on the reduction of using ZnO particles in related industries, the use of ZnO nanoparticles has had better results than its particles. In addition, due to the less environmental effects of magnesium oxide, magnesium oxide nanoparticles can be used instead of micronutrients of zinc oxide. Overall, the results of various investigations show that reducing the diameter of the zinc oxide particles reduces the amount required for curing the rubber and thus reduces its toxic effects. Also, the use of magnesium oxide nanoparticles instead of zinc oxide in different concentrations is investigated.
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Figueroa, Eric E., and Jerod S. Denton. "Zinc pyrithione activates the volume-regulated anion channel through an antioxidant-sensitive mechanism." American Journal of Physiology-Cell Physiology 320, no. 6 (2021): C1088—C1098. http://dx.doi.org/10.1152/ajpcell.00070.2021.
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Leucine-rich repeat-containing 8 (LRRC8) volume-regulated anion channels (VRACs) play important physiological roles in diverse cell types and may represent therapeutic targets for various diseases. To date, however, the pharmacological tools for evaluating the druggability of VRACs have been limited to inhibitors, as no activators of the channel have been reported. We therefore performed a fluorescence-based high-throughput screening (HTS) of 1,184 Food and Drug Administration-approved drugs for compounds that increase VRAC activity. The most potent VRAC potentiator identified was zinc pyrithione (ZPT), which is used commercially as an antifouling agent and for treating dandruff and other skin disorders. In intracellular Yellow Fluorescent Protein YFP(F46L/H148Q/I152L)-quenching assays, ZPT potentiates the rate and extent of swelling-induced iodide influx dose dependently with a half-maximal effective concentration (EC50) of 5.7 µM. Whole cell voltage-clamp experiments revealed that coapplication of hypotonic solution and 30 µM ZPT to human embryonic kidney 293 or human colorectal carcinoma 116 cells increases the rate of swelling-induced VRAC activation by approximately 10-fold. ZPT potentiates swelling-induced VRAC currents after currents have reached a steady state and activates currents in the absence of cell swelling. Neither ZnCl2 nor free pyrithione activated VRAC; however, treating cells with a mixture of ZnCl2 and pyrithione led to robust channel activation. Finally, the effects of ZPT on VRAC were inhibited by reactive oxygen species (ROS) scavenger N-acetylcysteine (NAC) and NAD(P)H oxidase inhibitor diphenyleneiodonium chloride, suggesting the mechanism of action involves ROS generation. The discovery of ZPT as a potentiator/activator of VRAC demonstrates the utility of HTS for identifying small-molecule modulators of VRAC and adds to a growing repertoire of pharmacological tool compounds for probing the molecular physiology and regulation of this important channel.
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Sunkara, Jhansi R., and Sathish M. Botsa. "Facile Synthesis of 1,8-dioxooctahydro Xanthenes by Reusable Zinc Sulfide based Ternary Nanocomposite via Hydrothermal Route." Current Catalysis 9, no. 1 (2020): 72–79. http://dx.doi.org/10.2174/2211544708666191112120505.
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Background: Metal oxide or metal oxide composite nanoparticles are attaining tremendous importance due to their catalytic activities for various organic transformations. Objective: To report the one-pot synthesis of xanthene derivatives prepared by ZnS-Fe2O3-Ag composite under solvent-free conditions. Method: To prepare nanocomposite by a facile and simple hydrothermal approach. Results: The prepared composite is smaller (17.56 nm) in size and can be easily separable, recycled and reused six times without any significant loss of catalytic activity with excellent yields. In short reaction time, great catalytic activity was perceived with no co-catalyst and any other activator. Conclusion: In conclusion, ZnS-Fe2O3-Ag composite provides a simple, economical, efficient and greener method for the synthesis of one-pot multicomponent reaction of aldehyde with 1,3-diketones under solvent free conditions for the synthesis of 1,8-dioxooctahydro xanthenes. In short reaction time, great catalytic activity was perceived with no co-catalyst and any other activator.
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Xie, Zhigang, Wei Guan, Fangying Ji, Zhongrong Song, and Yanling Zhao. "Production of Biologically Activated Carbon from Orange Peel and Landfill Leachate Subsequent Treatment Technology." Journal of Chemistry 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/491912.
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In order to improve adsorption of macromolecular contaminants and promote the growth of microorganisms, active carbon for biological wastewater treatment or follow-up processing requires abundant mesopore and good biophile ability. In this experiment, biophile mesopore active carbon is produced in one-step activation with orange peel as raw material, and zinc chloride as activator, and the adsorption characteristics of orange peel active carbon is studied by static adsorption method. BET specific surface area and pore volume reached 1477 m2/g and 2.090 m3/g, respectively. The surface functional groups were examined by Fourier transform infrared spectroscopy (FT-IR). The surface of the as-prepared activated carbon contained hydroxyl group, carbonyl group, and methoxy group. The analysis based on X-ray diffraction spectrogram (XRD) and three-dimensional fluorescence spectrum indicated that the as-prepared activated carbon, with smaller microcrystalline diameter and microcrystalline thickness and enhanced reactivity, exhibited enhanced adsorption performance. This research has a deep influence in effectively controlling water pollution, improving area water quality, easing orange peel waste pollution, and promoting coordinated development among society, economy, and environment.
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Alam, Md Najib, Vineet Kumar, and Sang-Shin Park. "Advances in Rubber Compounds Using ZnO and MgO as Co-Cure Activators." Polymers 14, no. 23 (2022): 5289. http://dx.doi.org/10.3390/polym14235289.
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Zinc oxide performs as the best cure activator in sulfur-based vulcanization of rubber, but it is regarded as a highly toxic material for aquatic organisms. Hence, the toxic cure activator should be replaced by a non-toxic one. Still, there is no suitable alternative industrially. However, binary activators combining ZnO and another metal oxide such as MgO can largely reduce the level of ZnO with some improved benefits in the vulcanization of rubber as investigated in this research. Curing, mechanical, and thermal characteristics were investigated to find out the suitability of MgO in the vulcanization of rubber. Curing studies reveal that significant reductions in the optimum curing times are found by using MgO as a co-cure activator. Especially, the rate of vulcanization with conventional 5 phr (per hundred grams) ZnO can be enhanced by more than double, going from 0.3 Nm/min to 0.85 Nm/min by the use of a 3:2 ratio of MgO to ZnO cure activator system that should have high industrial importance. Mechanical and thermal properties investigations suggest that MgO as a co-cure activator used at 60% can provide 7.5% higher M100 (modulus at 100% strain) (0.58 MPa from 0.54 MPa), 20% higher tensile strength (23.7 MPa from 19.5 MPa), 15% higher elongation at break (1455% from 1270%), 68% higher fracture toughness (126 MJ/m3 from 75 MJ/m3), and comparable thermal stability than conventionally using 100 % ZnO. Especially, MgO as a co-cure activator could be very useful for improving the fracture toughness in rubber compounds compared to ZnO as a single-site curing activator. The significant improvements in the curing and mechanical properties suggest that MgO and ZnO undergo chemical interactions during vulcanization. Such rubber compounds can be useful in advanced tough and stretchable applications.
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Darmayanti, Lita, Suprihanto Notodarmojo, Enri Damanhuri, Grandprix T. M. Kadja, and Rino R Mukti. "Preparation of alkali-activated fly ash-based geopolymer and their application in the adsorption of copper (II) and zinc (II) ions." MATEC Web of Conferences 276 (2019): 06012. http://dx.doi.org/10.1051/matecconf/201927606012.
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Alkali activation of fly ash can a promising alternative of the system to improve adsorption capability of fly ash. In finding the best chemical composition of the activator solution, geopolymer has been synthesized using molar ratios of Na2O/SiO2 0.16, 0.3, and 0.5 (Gr1, Gr3, Gr5). The results indicated that the geopolymer synthesized with a ratio molar of Na2O/SiO2 0.3 (Gr3) improved the adsorption properties of fly ash substantially. Gr3 was characterized by BET, XRD, and FTIR. The batch experiment was conducted at the different duration and initial concentrations. The equilibrium sorption data were fitted for the Langmuir and Freundlich equations. The maximum sorption capacities calculated from Langmuir isotherm was 54 mg g-1 and 47 mg g-1 for Cu (II) and Zn (II) respectively. The kinetic data reveal that the pseudo-second order model was appropriate for a description of the kinetic performance.
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Troconis de Rincón, Oladis, Andrés Torres-Acosta, Alberto Sagüés, and Miguel Martinez-Madrid. "Galvanic Anodes for Reinforced Concrete Structures: A Review." Corrosion 74, no. 6 (2018): 715–23. http://dx.doi.org/10.5006/2613.
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In recent years, the use of sacrificial anodes for cathodic protection in reinforced concrete structures has increased, reflecting ease of installation, low-maintenance requirements, as well as desirability in prestressed concrete structures where the naturally controlled protection potential decreases the risk of hydrogen embrittlement. Zinc-based alloys have been among the most evaluated galvanic materials for concrete structures, especially in the United States, in many applications: thermal spray, superficial metal/mesh with and without hydrogel adhesive, embedded in concrete (point anodes) with or without salt activator, etc. However, the protection capacity lifetime of zinc alloys as used has been questioned based both on laboratory and on field application studies. Aluminum alloys have also been evaluated, sometimes showing better results as anode materials than zinc alloys. However, both zinc and aluminum alloy anodes may experience limited applicability in concrete structures exposed only to atmospheric conditions, as opposed to those in immersed, tidal, and splash zone service. This paper presents a review of the research work in the literature to date for both laboratory and field evaluations, toward identifying technically relevant situations where the use of sacrificial anodes may or may not be a practical option for reinforcement protection in concrete structures.
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Petrova A. V., Sidorova A. V., Sergeeva I. A., and Petrova G. P. "Evaluation of the influence of chromium and zinc ions on the collagenolysis process in solutions by the method of dynamic light scattering." Optics and Spectroscopy 130, no. 6 (2022): 663. http://dx.doi.org/10.21883/eos.2022.06.54701.23-22.
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Using the method of dynamic light scattering, it was found that the rate of collagen cleavage under the influence of bacterial collagenase decreases by almost 4 times when protein molecules are doped with Cr3+ ions, and when the enzyme activator of Zn2+ ions is added, it increases by 1.3 times. Based on the experimental data, the reaction rate constants k1 were calculated. It was found that when collagen molecules are tanned with a chromium salt, it becomes more resistant to degradation in solutions containing zinc ions than in solutions with the addition of calcium ions, as we described in earlier works. Keywords: collagen type 1, bacterial collagenase, chromium chloride, zinc chloride, dynamic light scattering method, translational diffusion coefficient, hydrodynamic radius, reaction rate constant, collagenolysis, Clostridium histolyticum.
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Pu, Mengjie, Daqi Ye, Jinquan Wan, Bentuo Xu, Wei Sun, and Wei Li. "Zinc-based metal–organic framework nanofibers membrane ZIF-65/PAN as efficient peroxymonosulfate activator to degrade aqueous ciprofloxacin." Separation and Purification Technology 299 (October 2022): 121716. http://dx.doi.org/10.1016/j.seppur.2022.121716.
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Xu, Tao, Yongchao Li, Joy D. Van Nostrand, Zhili He, and Jizhong Zhou. "Cas9-Based Tools for Targeted Genome Editing and Transcriptional Control." Applied and Environmental Microbiology 80, no. 5 (2014): 1544–52. http://dx.doi.org/10.1128/aem.03786-13.
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ABSTRACTDevelopment of tools for targeted genome editing and regulation of gene expression has significantly expanded our ability to elucidate the mechanisms of interesting biological phenomena and to engineer desirable biological systems. Recent rapid progress in the study of a clustered, regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated (Cas) protein system in bacteria has facilitated the development of newly facile and programmable platforms for genome editing and transcriptional control in a sequence-specific manner. The core RNA-guided Cas9 endonuclease in the type II CRISPR system has been harnessed to realize gene mutation and DNA deletion and insertion, as well as transcriptional activation and repression, with multiplex targeting ability, just by customizing 20-nucleotide RNA components. Here we describe the molecular basis of the type II CRISPR/Cas system and summarize applications and factors affecting its utilization in model organisms. We also discuss the advantages and disadvantages of Cas9-based tools in comparison with widely used customizable tools, such as Zinc finger nucleases and transcription activator-like effector nucleases.
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Wallis, Christopher P., Louis H. Scott, Aleksandra Filipovska, and Oliver Rackham. "Manipulating and elucidating mitochondrial gene expression with engineered proteins." Philosophical Transactions of the Royal Society B: Biological Sciences 375, no. 1790 (2019): 20190185. http://dx.doi.org/10.1098/rstb.2019.0185.
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Many conventional, modern genome engineering tools cannot be used to study mitochondrial genetics due to the unusual structure and physiology of the mitochondrial genome. Here, we review a number of newly developed, synthetic biology-based approaches for altering levels of mutant mammalian mitochondrial DNA and mitochondrial RNAs, including transcription activator-like effector nucleases, zinc finger nucleases and engineered RNA-binding proteins. These approaches allow researchers to manipulate and visualize mitochondrial processes and may provide future therapeutics. This article is part of the theme issue ‘Linking the mitochondrial genotype to phenotype: a complex endeavour’.
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Sandalov, S. I., N. F. Ushmarin, N. A. Chernova, and N. I. Kol'tsov. "Investigating Zinc Methacrylate as An activator of the Peroxide vulcanisation of A Rubber Mix Based on Nitrile Butadiene Rubber." International Polymer Science and Technology 40, no. 11 (2013): T25—T27. http://dx.doi.org/10.1177/0307174x1304001110.
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Männistö, Riina H., A. Marika Grahn, Dennis H. Bamford, and Jaana K. H. Bamford. "Transcription of Bacteriophage PM2 Involves Phage-Encoded Regulators of Heterologous Origin." Journal of Bacteriology 185, no. 11 (2003): 3278–87. http://dx.doi.org/10.1128/jb.185.11.3278-3287.2003.
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ABSTRACT Bacteriophage PM2 is the only described member of the Corticoviridae family. It is an icosahedral dsDNA virus with a membrane residing underneath the protein coat. PM2 infects some gram-negative Pseudoalteromonas spp. In the present study, we mapped the viral promoters and showed that the PM2 genome consists of three operons. Four new virus genes were assigned based on their function in transcription. Proteins P15 and P16 are shown to repress early transcription, and proteins P13 and P14 are shown to activate late transcription events. The early regulatory region, containing genes for proteins P15 and P16, as well as the newly identified early promoter region in PM2, has significant sequence similarity with the Pseudoalteromonas pAS28 plasmid. P14, the transcription activator for the structural genes, has a zinc finger motif homologous to archaeal and eukaryotic TFIIS-type regulatory factors.
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Петрова, А. В., А. В. Сидорова, И. А. Сергеева та Г. П. Петрова. "Оценка влияния ионов хрома и цинка на процесс коллагенолиза в растворах методом динамического рассеяния света". Оптика и спектроскопия 130, № 6 (2022): 838. http://dx.doi.org/10.21883/os.2022.06.52624.23-22.
Texte intégralRésumé :
Using the method of dynamic light scattering, it was found that the rate of collagen cleavage under the influence of bacterial collagenase decreases by almost 4 times when protein molecules are doped with Cr3+ ions, and when the enzyme activator of Zn2+ ions is added, it increases by 1.3 times. Based on the experimental data, the reaction rate constants k1 were calculated. It was found that when collagen molecules are tanned with a chromium salt, it becomes more resistant to degradation in solutions containing zinc ions than in solutions with the addition of calcium ions, as we described in earlier works.
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Taghvaei-Ganjali, Saeed, Mercedeh Malekzadeh, Mona Farahani, Ali Abbasian, and Morteza khosravi. "Effect of surface-modified zinc oxide as cure activator on the properties of a rubber compound based on NR/SBR." Journal of Applied Polymer Science 122, no. 1 (2011): 249–56. http://dx.doi.org/10.1002/app.33919.
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Riggs, K. J., S. Saleque, K. K. Wong, et al. "Yin-yang 1 activates the c-myc promoter." Molecular and Cellular Biology 13, no. 12 (1993): 7487–95. http://dx.doi.org/10.1128/mcb.13.12.7487-7495.1993.
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Previous studies on the murine c-myc promoter demonstrated that a ubiquitously present protein, common factor 1 (CF1), bound at two sites located -260 and -390 bp from the P1 transcription start site. CF1 has been purified to near homogeneity and shown to be identical to the zinc finger protein Yin-yang 1 (YY1) as judged by similarity of molecular weight and other biochemical properties, immunological cross-reactivity, and the ability of recombinant YY1 to bind to CF1 sites. In cotransfection experiments, YY1 is a strong activator of transcription from c-myc promoter-based reporters. Furthermore, in murine erythroleukemia cells, overexpressed YY1 causes increased levels of c-myc mRNA initiated from both major transcription initiation sites of the endogenous c-myc gene.
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Riggs, K. J., S. Saleque, K. K. Wong, et al. "Yin-yang 1 activates the c-myc promoter." Molecular and Cellular Biology 13, no. 12 (1993): 7487–95. http://dx.doi.org/10.1128/mcb.13.12.7487.
Texte intégralRésumé :
Previous studies on the murine c-myc promoter demonstrated that a ubiquitously present protein, common factor 1 (CF1), bound at two sites located -260 and -390 bp from the P1 transcription start site. CF1 has been purified to near homogeneity and shown to be identical to the zinc finger protein Yin-yang 1 (YY1) as judged by similarity of molecular weight and other biochemical properties, immunological cross-reactivity, and the ability of recombinant YY1 to bind to CF1 sites. In cotransfection experiments, YY1 is a strong activator of transcription from c-myc promoter-based reporters. Furthermore, in murine erythroleukemia cells, overexpressed YY1 causes increased levels of c-myc mRNA initiated from both major transcription initiation sites of the endogenous c-myc gene.
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Pang, Xie Guan, Tien Yew Eeu, Pau Ming Leong, Wan Nurulhuda Wan Shamsuri, and Rosli Hussin. "Structural and Luminescence Study of Rare Earth and Transition Metal Ions Doped Lead Zinc Borophosphate Glasses." Advanced Materials Research 895 (February 2014): 280–83. http://dx.doi.org/10.4028/www.scientific.net/amr.895.280.
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A series of glasses with composition of xPbO-(50-x)ZnO-yB2O3-(50-y)P2O5 with 0 x 50 mol% and 10 y 20 mol% were prepared by melt quenching technique, with 30 minutes pre-heating and 10 minutes for melting. The structural properties of prepared samples were studied using Fourier Transform-Infrared spectroscopy. The glasses were mainly based on PO2, BOP and BO3 unit. In order to obtain luminescence properties, another series of sample at composition 20PbO-30ZnO-10B2O3-40P2O5 doped with Fe2+, Ti2+, Y2+ and Nd2+ were prepared. These samples were investigated using Photoluminescence Spectroscopy with different excitation wavelength to compare results. Results showed that with the presence of rare earth and transition metal ions as activator in lead zinc borophosphate glass system give rise to luminescence of visible light.
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Xu, Xiao Yan, Guo Tong Qian, Jian Zhou, Yao Yao, and Xu Chen. "Wettability of Sn-Zn Lead-Free Solder on Aluminum Substrate." Advanced Materials Research 815 (October 2013): 48–54. http://dx.doi.org/10.4028/www.scientific.net/amr.815.48.
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The effects of flux components and compositions of solder alloys on the wettability of the Sn-Zn alloys on aluminum surface was investigated. The results show that the wettability of the Sn-9Zn solder on aluminum substrate improved with flux of double solvents composed of diethanolamine and triethanolamine, which is better than single solvent. When flux is composed of 3% zinc fluoborate as activator and 30% triethanolamine plus 67% diethanolamine as double solvents, the spreading area of the Sn-9Zn solder reaches to 75%. Trace addition (0.002%-0.005%) of Al results in significant improvement of the wettability of the Sn-9Zn based solder. However, additions of Bi or Sb are not beneficial to the wettability of the solder on aluminum substrate.
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Konjevic, Gordana, and Sandra Stankovic. "Matrix metalloproteinases in the process of invasion and metastasis of breast cancer." Archive of Oncology 14, no. 3-4 (2006): 136–40. http://dx.doi.org/10.2298/aoo0604136k.
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Metastatic cascade in malignant tumors, including breast cancer, starts with localized invasion of the host tissue. This process, requiring that tumor cells separate from each other, includes loss of homotypic and heterotypic cell adhesion and cell-cell contact inhibition, acquisition of motility, exacerbated by "epithelial-to-mesenchymal transition", and production of proteolytic enzymes which degrade basal membrane and extracellular matrix. In this sense, aside from urokinase type plasminogen activator, increased expression and activity of matrix metalloproteinases (MMPs) is one of the earliest and most sustained events in tumor progression, playing a role in angiogenesis, invasion and metastasis. MMPs are a family of 23 zinc metalloproteinases, secreted as latent pro-enzymes, activated by proteolytic cleavage, and inhibited by the tissue inhibitors of metalloproteinases. The most commonly connected MMPs with the processes of metastasis are MMP-2 (gelatinase A) and MMP-9 (gelatinase B), due to their ability to degrade collagen type IV, major component of vascular basement membrane. MMP-2 and MMP-9 are also required for the switch to the "angiogenic phenotype" during tumor progression and activation of dormant tumor cells. The association of the increase in serum MMP-2 and MMP-9 activity and clinical stage suggests the usefulness of these parameters as markers in the follow-up and prognosis of breast cancer patients. The concept of "stromal-directed therapy" of cancer, with MMP-inhibitors directed against MMPs as targets, is based on the observed MMP up-regulation in tumors.
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Canver, Matthew C., та Stuart H. Orkin. "Customizing the genome as therapy for the β-hemoglobinopathies". Blood 127, № 21 (2016): 2536–45. http://dx.doi.org/10.1182/blood-2016-01-678128.
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Abstract Despite nearly complete understanding of the genetics of the β-hemoglobinopathies for several decades, definitive treatment options have lagged behind. Recent developments in technologies for facile manipulation of the genome (zinc finger nucleases, transcription activator-like effector nucleases, or clustered regularly interspaced short palindromic repeats–based nucleases) raise prospects for their clinical application. The use of genome-editing technologies in autologous CD34+ hematopoietic stem and progenitor cells represents a promising therapeutic avenue for the β-globin disorders. Genetic correction strategies relying on the homology-directed repair pathway may repair genetic defects, whereas genetic disruption strategies relying on the nonhomologous end joining pathway may induce compensatory fetal hemoglobin expression. Harnessing the power of genome editing may usher in a second-generation form of gene therapy for the β-globin disorders.
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Phan, Hong Thi Lam, Kyoungmi Kim, Ho Lee, and Je Kyung Seong. "Progress in and Prospects of Genome Editing Tools for Human Disease Model Development and Therapeutic Applications." Genes 14, no. 2 (2023): 483. http://dx.doi.org/10.3390/genes14020483.
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Programmable nucleases, such as zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and clustered regularly interspaced short palindromic repeats (CRISPR)/Cas, are widely accepted because of their diversity and enormous potential for targeted genomic modifications in eukaryotes and other animals. Moreover, rapid advances in genome editing tools have accelerated the ability to produce various genetically modified animal models for studying human diseases. Given the advances in gene editing tools, these animal models are gradually evolving toward mimicking human diseases through the introduction of human pathogenic mutations in their genome rather than the conventional gene knockout. In the present review, we summarize the current progress in and discuss the prospects for developing mouse models of human diseases and their therapeutic applications based on advances in the study of programmable nucleases.
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Radkowski, Adam, Iwona Radkowska, Tadeusz Lemek, and Tomasz Jakubowski. "Effect of Zinc Ammonium Acetate on Characteristics of Timothy Canopy and Seed Yield." Ecological Chemistry and Engineering S 26, no. 4 (2019): 797–806. http://dx.doi.org/10.1515/eces-2019-0056.
Texte intégralRésumé :
Abstract The purpose of the experiment was to assess the effect of application of zinc ammonium acetate (ZAA) on yielding, morphological features and on selected vegetation indices of timothy cv. ‘Owacja’ cultivated for seeds. Zinc ammonium acetate that has a biostimulatory effect was used foliar in the carried out experiment. The experiment was conducted in the years 2015-2017 at the experimental station in Prusy near Krakow, a part of the Experimental Station of the Institute of Crop Production of the University of Agriculture in Krakow. The field experiment was set up in a randomized block design, in four replications, and the area of experimental plots was 10 m2. Degraded Chernozem formed from loess (classified to the first class quality soil) was present on the experimental area. The experiment consisted in applying ZAA as spray at three doses: 0.214, 0.267 and 0.400 kg(ZnNH4(CH3CO2)3)/ha. Based on the obtained preliminary results, it was found that application of foliar activator in a higher dose (0.400 kg/ha) caused a significant (p ≤ 0.05) increase in seed yield, 1000-seed weight and in germination capacity in relation to the control. Improvement in morphological properties was also observed. Leaf greenness index (SPAD) was also determined. Its highest value was found in plants from the treatment where the highest dose of the zinc ammonium acetate was applied. Seeds obtained from plants treated with ZAA were riper (ripeness was measured with 1000-seed weight) and had higher germination capacity in relation to control treatments.
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Schreurs, Juliët, Claudia Sacchetto, Robin M. W. Colpaert, Libero Vitiello, Alessandra Rampazzo, and Martina Calore. "Recent Advances in CRISPR/Cas9-Based Genome Editing Tools for Cardiac Diseases." International Journal of Molecular Sciences 22, no. 20 (2021): 10985. http://dx.doi.org/10.3390/ijms222010985.
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In the past two decades, genome editing has proven its value as a powerful tool for modeling or even treating numerous diseases. After the development of protein-guided systems such as zinc finger nucleases (ZFNs) and transcription activator-like effector nucleases (TALENs), which for the first time made DNA editing an actual possibility, the advent of RNA-guided techniques has brought about an epochal change. Based on a bacterial anti-phage system, the CRISPR/Cas9 approach has provided a flexible and adaptable DNA-editing system that has been able to overcome several limitations associated with earlier methods, rapidly becoming the most common tool for both disease modeling and therapeutic studies. More recently, two novel CRISPR/Cas9-derived tools, namely base editing and prime editing, have further widened the range and accuracy of achievable genomic modifications. This review aims to provide an overview of the most recent developments in the genome-editing field and their applications in biomedical research, with a particular focus on models for the study and treatment of cardiac diseases.
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Urbano, Smith, Weeks, and Chatterjee. "Gene-Specific Targeting of DNA Methylation in the Mammalian Genome." Cancers 11, no. 10 (2019): 1515. http://dx.doi.org/10.3390/cancers11101515.
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DNA methylation is the most widely-studied epigenetic modification, playing a critical role in the regulation of gene expression. Dysregulation of DNA methylation is implicated in the pathogenesis of numerous diseases. For example, aberrant DNA methylation in promoter regions of tumor-suppressor genes has been strongly associated with the development and progression of many different tumors. Accordingly, technologies designed to manipulate DNA methylation at specific genomic loci are very important, especially in the context of cancer therapy. Traditionally, epigenomic editing technologies have centered around zinc finger proteins (ZFP)- and transcription activator-like effector protein (TALE)-based targeting. More recently, however, the emergence of clustered regulatory interspaced short palindromic repeats (CRISPR)-deactivated Cas9 (dCas9)-based editing systems have shown to be a more specific and efficient method for the targeted manipulation of DNA methylation. Here, we describe the regulation of the DNA methylome, its significance in cancer and the current state of locus-specific editing technologies for altering DNA methylation.
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Beil, J., L. Fairbairn, P. Pelczar, and T. Buch. "Is BAC Transgenesis Obsolete? State of the Art in the Era of Designer Nucleases." Journal of Biomedicine and Biotechnology 2012 (2012): 1–5. http://dx.doi.org/10.1155/2012/308414.
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DNA constructs based on bacterial artificial chromosomes (BACs) are frequently used to generate transgenic animals as they reduce the influence of position effects and allow predictable expression patterns for genes whose regulatory sequences are not fully identified. Despite these advantages BAC transgenics suffer from drawbacks such as complicated vector construction, low efficiency of transgenesis, and some remaining expression variegation. The recent development of transcription activator-like effector nucleases (TALENs) and zinc finger nucleases (ZFNs) has resulted in new transgenic techniques which do not have the drawbacks associated with BAC transgenesis. Initial reports indicate that such designer nucleases (DNs) allow the targeted insertion of transgenes into endogenous loci by direct injection of the targeting vector and mRNA/DNA encoding the predesigned nucleases into oocytes. This results in the transgene being inserted at a specific locus in the mouse genome, thus circumventing the drawbacks associated with BAC transgenesis.
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Ortiz-Vitali, Jose L., and Radbod Darabi. "iPSCs as a Platform for Disease Modeling, Drug Screening, and Personalized Therapy in Muscular Dystrophies." Cells 8, no. 1 (2019): 20. http://dx.doi.org/10.3390/cells8010020.
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Induced pluripotent stem cells (iPSCs) are the foundation of modern stem cell-based regenerative medicine, especially in the case of degenerative disorders, such as muscular dystrophies (MDs). Since their introduction in 2006, many studies have used iPSCs for disease modeling and identification of involved mechanisms, drug screening, as well as gene correction studies. In the case of muscular dystrophies, these studies commenced in 2008 and continue to address important issues, such as defining the main pathologic mechanisms in different types of MDs, drug screening to improve skeletal/cardiac muscle cell survival and to slow down disease progression, and evaluation of the efficiency of different gene correction approaches, such as exon skipping, Transcription activator-like effector nucleases (TALENs), Zinc finger nucleases (ZFNs) and RNA-guided endonuclease Cas9 (CRISPR/Cas9). In the current short review, we have summarized chronological progress of these studies and their key findings along with a perspective on the future road to successful iPSC-based cell therapy for MDs and the potential hurdles in this field.
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Thanh, Nguyen Duc. "Application of genome editing tools in plants." Vietnam Journal of Biotechnology 19, no. 1 (2021): 15–40. http://dx.doi.org/10.15625/1811-4989/15464.
Texte intégralRésumé :
Genome editing technology is the genome modification techniques, such as targeted mutagenesis or insert/delete/replacement at specific locations in the genome of living organisms. Genome editing is based on the creation of double sequence break (DSB) in a specific location and DNA repair via nonhomologous end joining (NHEJ) or homology direct repair (HDR). The development of sequence-specific nuclease (SSN) allows precise editing of the target gene. These SSNs include: meganuclease (MN), zinc finger nuclease (ZFN), transcription activator-like effector nuclease (TALEN) and CRISPR-associated nuclease (Cas) including CRISPR/Cas9 (from Streptococcus pyogenes) and CRISPR/Cpf1 (from Prevoltella and Francisella1). These are the genome editing tools used to create DSBs at specific locations of the genome. Recently, the base editing (BE) and prime editing (PE) tools have been reported. This review will cover the basics of these tools and their application in genome editing in plants, especially providing the most up-to-date information on their application in crop improvement.
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Kim, Daesik, Kevin Luk, Scot A. Wolfe, and Jin-Soo Kim. "Evaluating and Enhancing Target Specificity of Gene-Editing Nucleases and Deaminases." Annual Review of Biochemistry 88, no. 1 (2019): 191–220. http://dx.doi.org/10.1146/annurev-biochem-013118-111730.
Texte intégralRésumé :
Programmable nucleases and deaminases, which include zinc-finger nucleases, transcription activator-like effector nucleases, CRISPR RNA-guided nucleases, and RNA-guided base editors, are now widely employed for the targeted modification of genomes in cells and organisms. These gene-editing tools hold tremendous promise for therapeutic applications. Importantly, these nucleases and deaminases may display off-target activity through the recognition of near-cognate DNA sequences to their target sites, resulting in collateral damage to the genome in the form of local mutagenesis or genomic rearrangements. For therapeutic genome-editing applications with these classes of programmable enzymes, it is essential to measure and limit genome-wide off-target activity. Herein, we discuss the key determinants of off-target activity for these systems. We describe various cell-based and cell-free methods for identifying genome-wide off-target sites and diverse strategies that have been developed for reducing the off-target activity of programmable gene-editing enzymes.
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V., Raja, Selvan G., Anbarasu R., and Baskar S. "Green synthesis of zinc oxide nanoparticles using Hyptis leaf extract and Activated carbon based Zinc oxide composite of Supercapacitor Applications." Indian Journal of Science and Technology 12, no. 40 (2019): 107–8. http://dx.doi.org/10.17485/ijst/2019/v12i40/148040.
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Geel, T. M., M. H. J. Ruiters, R. H. Cool, et al. "The past and presence of gene targeting: from chemicals and DNA via proteins to RNA." Philosophical Transactions of the Royal Society B: Biological Sciences 373, no. 1748 (2018): 20170077. http://dx.doi.org/10.1098/rstb.2017.0077.
Texte intégralRésumé :
The ability to target DNA specifically at any given position within the genome allows many intriguing possibilities and has inspired scientists for decades. Early gene-targeting efforts exploited chemicals or DNA oligonucleotides to interfere with the DNA at a given location in order to inactivate a gene or to correct mutations. We here describe an example towards correcting a genetic mutation underlying Pompe's disease using a nucleotide-fused nuclease (TFO-MunI). In addition to the promise of gene correction, scientists soon realized that genes could be inactivated or even re-activated without inducing potentially harmful DNA damage by targeting transcriptional modulators to a particular gene. However, it proved difficult to fuse protein effector domains to the first generation of programmable DNA-binding agents. The engineering of gene-targeting proteins (zinc finger proteins (ZFPs), transcription activator-like effectors (TALEs)) circumvented this problem. The disadvantage of protein-based gene targeting is that a fusion protein needs to be engineered for every locus. The recent introduction of CRISPR/Cas offers a flexible approach to target a (fusion) protein to the locus of interest using cheap designer RNA molecules. Many research groups now exploit this platform and the first human clinical trials have been initiated: CRISPR/Cas has kicked off a new era of gene targeting and is revolutionizing biomedical sciences. This article is part of a discussion meeting issue ‘Frontiers in epigenetic chemical biology’.
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Psatha, Nikoletta, Kiriaki Paschoudi, Anastasia Papadopoulou, and Evangelia Yannaki. "In Vivo Hematopoietic Stem Cell Genome Editing: Perspectives and Limitations." Genes 13, no. 12 (2022): 2222. http://dx.doi.org/10.3390/genes13122222.
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The tremendous evolution of genome-editing tools in the last two decades has provided innovative and effective approaches for gene therapy of congenital and acquired diseases. Zinc-finger nucleases (ZFNs), transcription activator- like effector nucleases (TALENs) and CRISPR-Cas9 have been already applied by ex vivo hematopoietic stem cell (HSC) gene therapy in genetic diseases (i.e., Hemoglobinopathies, Fanconi anemia and hereditary Immunodeficiencies) as well as infectious diseases (i.e., HIV), and the recent development of CRISPR-Cas9-based systems using base and prime editors as well as epigenome editors has provided safer tools for gene therapy. The ex vivo approach for gene addition or editing of HSCs, however, is complex, invasive, technically challenging, costly and not free of toxicity. In vivo gene addition or editing promise to transform gene therapy from a highly sophisticated strategy to a “user-friendly’ approach to eventually become a broadly available, highly accessible and potentially affordable treatment modality. In the present review article, based on the lessons gained by more than 3 decades of ex vivo HSC gene therapy, we discuss the concept, the tools, the progress made and the challenges to clinical translation of in vivo HSC gene editing.
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Baya, Georgina, Stephen Muhindi, Valentine Ngendahimana, and Jonathan Caguiat. "Potential Whole-Cell Biosensors for Detection of Metal Using MerR Family Proteins from Enterobacter sp. YSU and Stenotrophomonas maltophilia OR02." Micromachines 12, no. 2 (2021): 142. http://dx.doi.org/10.3390/mi12020142.
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Cell-based biosensors harness a cell’s ability to respond to the environment by repurposing its sensing mechanisms. MerR family proteins are activator/repressor switches that regulate the expression of bacterial metal resistance genes and have been used in metal biosensors. Upon metal binding, a conformational change switches gene expression from off to on. The genomes of the multimetal resistant bacterial strains, Stenotrophomonas maltophilia Oak Ridge strain 02 (S. maltophilia 02) and Enterobacter sp. YSU, were recently sequenced. Sequence analysis and gene cloning identified three mercury resistance operons and three MerR switches in these strains. Transposon mutagenesis and sequence analysis identified Enterobacter sp. YSU zinc and copper resistance operons, which appear to be regulated by the protein switches, ZntR and CueR, respectively. Sequence analysis and reverse transcriptase polymerase chain reaction (RT-PCR) showed that a CueR switch appears to activate a S. maltophilia 02 copper transport gene in the presence of CuSO4 and HAuCl4·3H2O. In previous studies, genetic engineering replaced metal resistance genes with the reporter genes for β-galactosidase, luciferase or the green fluorescence protein (GFP). These produce a color change of a reagent, produce light, or fluoresce in the presence of ultraviolet (UV) light, respectively. Coupling these discovered operons with reporter genes has the potential to create whole-cell biosensors for HgCl2, ZnCl2, CuSO4 and HAuCl4·3H2O.
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Liu, Pei-Qi, Siyuan Tan, Matthew C. Mendel, et al. "Isogenic Human Cell Lines for Drug Discovery: Regulation of Target Gene Expression by Engineered Zinc-Finger Protein Transcription Factors." Journal of Biomolecular Screening 10, no. 4 (2005): 304–13. http://dx.doi.org/10.1177/1087057104272663.
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Isogenic cell lines differing only in the expression of the protein of interest provide the ideal platform for cell-based screening. However, related natural lines differentially expressing the therapeutic target of choice are rare. Here the authors report a strategy for drug screening employing isogenic human cell lines in which the expression of the target protein is regulated by a gene-specific engineered zinc-finger protein (ZFP) transcription factor (TF). To demonstrate this approach, a ZFP TF activator of the human parathyroid hormone receptor 1 (PTHR1) gene was identified and introduced into HEK293 cells (negative for PTHR1). Following induction of ZFP TF expression, this cell line produced functional PTHR1 protein, resulting in a robust and ligand-specific cyclic adenosine monophosphate (cAMP) response. Reciprocally, the natural expression of PTHR1 observed in SAOS2 cells was dramatically reduced by the introduction of the appropriate PTHR1-specific ZFP TF repressor. Moreover, this ZFP-driven PTHR1 repression selectively eliminated the functional cAMP response invoked by known ligands of PTHR1. These data establish ZFP TF–generated isogenic lines as a general approach for the identification of therapeutic agents specific for the target gene of interest.
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Bondareva, Olga, Roman Tsaryk, Vesna Bojovic, Maria Odenthal-Schnittler, Arndt F. Siekmann, and Hans-J. Schnittler. "Identification of atheroprone shear stress responsive regulatory elements in endothelial cells." Cardiovascular Research 115, no. 10 (2019): 1487–99. http://dx.doi.org/10.1093/cvr/cvz027.
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Abstract Aims Oscillatory shear stress (OSS) is an atheroprone haemodynamic force that occurs in areas of vessel irregularities and is implicated in the pathogenesis of atherosclerosis. Changes in signalling and transcriptional programme in response to OSS have been vigorously studied; however, the underlying changes in the chromatin landscape controlling transcription remain to be elucidated. Here, we investigated the changes in the regulatory element (RE) landscape of endothelial cells under atheroprone OSS conditions in an in vitro model. Methods and results Analyses of H3K27ac chromatin immunoprecipitation-Seq enrichment and RNA-Seq in primary human umbilical vein endothelial cells 6 h after onset of OSS identified 2806 differential responsive REs and 33 differentially expressed genes compared with control cells kept under static conditions. Furthermore, gene ontology analyses of putative RE-associated genes uncovered enrichment of WNT/HIPPO pathway and cytoskeleton reorganization signatures. Transcription factor (TF) binding motif analysis within RE sequences identified over-representation of ETS, Zinc finger, and activator protein 1 TF families that regulate cell cycle, proliferation, and apoptosis, implicating them in the development of atherosclerosis. Importantly, we confirmed the activation of EGR1 as well as the YAP/TAZ complex early (6 h) after onset of OSS in both cultured human vein and artery endothelial cells and, by undertaking luciferase assays, functionally verified their role in RE activation in response to OSS. Conclusions Based on the identification and verification of specific responsive REs early upon OSS exposure, we propose an expanded mechanism of how OSS might contribute to the development of atherosclerosis.
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Yu, N., J. Yang, Y. Mishina, and W. V. Giannobile. "Genome Editing: A New Horizon for Oral and Craniofacial Research." Journal of Dental Research 98, no. 1 (2018): 36–45. http://dx.doi.org/10.1177/0022034518805978.
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Precise and efficient genetic manipulations have enabled researchers to understand gene functions in disease and development, providing a platform to search for molecular cures. Over the past decade, the unprecedented advancement of genome editing techniques has revolutionized the biological research fields. Early genome editing strategies involved many naturally occurring nucleases, including meganucleases, zinc finger nucleases, and transcription activator-like effector-based nucleases. More recently, the clustered regularly interspaced short palindromic repeats (CRISPR) / CRISPR-associated nucleases (CRISPR/Cas) system has greatly enriched genetic manipulation methods in conducting research. Those nucleases generate double-strand breaks in the target gene sequences and then utilize DNA repair mechanisms to permit precise yet versatile genetic manipulations. The oral and craniofacial field harbors a plethora of diseases and developmental defects that require genetic models that can exploit these genome editing techniques. This review provides an overview of the genome editing techniques, particularly the CRISPR/Cas9 technique, for the oral and craniofacial research community. We also discuss the details about the emerging applications of genome editing in oral and craniofacial biology.
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Karpe, Yashashree, Zhenyu Chen, and Xue-Jun Li. "Stem Cell Models and Gene Targeting for Human Motor Neuron Diseases." Pharmaceuticals 14, no. 6 (2021): 565. http://dx.doi.org/10.3390/ph14060565.
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Motor neurons are large projection neurons classified into upper and lower motor neurons responsible for controlling the movement of muscles. Degeneration of motor neurons results in progressive muscle weakness, which underlies several debilitating neurological disorders including amyotrophic lateral sclerosis (ALS), hereditary spastic paraplegias (HSP), and spinal muscular atrophy (SMA). With the development of induced pluripotent stem cell (iPSC) technology, human iPSCs can be derived from patients and further differentiated into motor neurons. Motor neuron disease models can also be generated by genetically modifying human pluripotent stem cells. The efficiency of gene targeting in human cells had been very low, but is greatly improved with recent gene editing technologies such as zinc-finger nucleases (ZFN), transcription activator-like effector nucleases (TALEN), and CRISPR-Cas9. The combination of human stem cell-based models and gene editing tools provides unique paradigms to dissect pathogenic mechanisms and to explore therapeutics for these devastating diseases. Owing to the critical role of several genes in the etiology of motor neuron diseases, targeted gene therapies have been developed, including antisense oligonucleotides, viral-based gene delivery, and in situ gene editing. This review summarizes recent advancements in these areas and discusses future challenges toward the development of transformative medicines for motor neuron diseases.
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Omelina, E. S., and A. V. Pindyurin. "Optogenetic regulation of endogenous gene transcription in mammals." Vavilov Journal of Genetics and Breeding 23, no. 2 (2019): 219–25. http://dx.doi.org/10.18699/vj19.485.
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Despite the rapid development of approaches aimed to precisely control transcription of exogenous genes in time and space, design of systems providing similar tight regulation of endogenous gene expression is much more challenging. However, finding ways to control the activity of endogenous genes is absolutely necessary for further progress in safe and effective gene therapies and regenerative medicine. In addition, such systems are of particular interest for genetics, molecular and cell biology. An ideal system should ensure tunable and reversible spatio-temporal control over transcriptional activity of a gene of interest. Although there are drug-inducible systems for transcriptional regulation of endogenous genes, optogenetic approaches seem to be the most promising for the gene therapy applications, as they are noninvasive and do not exhibit toxicity in comparison with druginducible systems. Moreover, they are not dependent on chemical inducer diffusion rate or pharmacokinetics and exhibit fast activation-deactivation switching. Among optogenetic tools, long-wavelength light-controlled systems are more preferable for use in mammalian tissues in comparison with tools utilizing shorter wavelengths, since far-red/near-infrared light has the maximum penetration depth due to lower light scattering caused by lipids and reduced tissue autofluorescence at wavelengths above 700 nm. Here, we review such light-inducible systems, which are based on synthetic factors that can be targeted to any desired DNA sequence and provide activation or repression of a gene of interest. The factors include zinc finger proteins, transcription activator-like effectors (TALEs), and the CRISPR/Cas9 technology. We also discuss the advantages and disadvantages of these DNA targeting tools in the context of the light-inducible gene regulation systems.
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Carrington, Blake, Kevin Bishop, and Raman Sood. "A Comprehensive Review of Indel Detection Methods for Identification of Zebrafish Knockout Mutants Generated by Genome-Editing Nucleases." Genes 13, no. 5 (2022): 857. http://dx.doi.org/10.3390/genes13050857.
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The use of zebrafish in functional genomics and disease modeling has become popular due to the ease of targeted mutagenesis with genome editing nucleases, i.e., zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and clustered regularly interspaced short palindromic repeats/Cas9 (CRISPR/Cas9). These nucleases, specifically CRISPR/Cas9, are routinely used to generate gene knockout mutants by causing a double stranded break at the desired site in the target gene and selecting for frameshift insertions or deletions (indels) caused by the errors during the repair process. Thus, a variety of methods have been developed to identify fish with indels during the process of mutant generation and phenotypic analysis. These methods range from PCR and gel-based low-throughput methods to high-throughput methods requiring specific reagents and/or equipment. Here, we provide a comprehensive review of currently used indel detection methods in zebrafish. By discussing the molecular basis for each method as well as their pros and cons, we hope that this review will serve as a comprehensive resource for zebrafish researchers, allowing them to choose the most appropriate method depending upon their budget, access to required equipment and the throughput needs of the projects.
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Negishi, Masahiko, Kaoru Kobayashi, Tsutomu Sakuma, and Tatsuya Sueyoshi. "Nuclear receptor phosphorylation in xenobiotic signal transduction." Journal of Biological Chemistry 295, no. 45 (2020): 15210–25. http://dx.doi.org/10.1074/jbc.rev120.007933.
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Nuclear pregnane X receptor (PXR, NR1I2) and constitutive active/androstane receptor (CAR, NR1I3) are nuclear receptors characterized in 1998 by their capability to respond to xenobiotics and activate cytochrome P450 (CYP) genes. An anti-epileptic drug, phenobarbital (PB), activates CAR and its target CYP2B genes, whereas PXR is activated by drugs such as rifampicin and statins for the CYP3A genes. Inevitably, both nuclear receptors have been investigated as ligand-activated nuclear receptors by identifying and characterizing xenobiotics and therapeutics that directly bind CAR and/or PXR to activate them. However, PB, which does not bind CAR directly, presented an alternative research avenue for an indirect ligand-mediated nuclear receptor activation mechanism: phosphorylation-mediated signal regulation. This review summarizes phosphorylation-based mechanisms utilized by xenobiotics to elicit cell signaling. First, the review presents how PB activates CAR (and other nuclear receptors) through a conserved phosphorylation motif located between two zinc fingers within its DNA-binding domain. PB-regulated phosphorylation at this motif enables nuclear receptors to form communication networks, integrating their functions. Next, the review discusses xenobiotic-induced PXR activation in the absence of the conserved DNA-binding domain phosphorylation motif. In this case, phosphorylation occurs at a motif located within the ligand-binding domain to transduce cell signaling that regulates hepatic energy metabolism. Finally, the review delves into the implications of xenobiotic-induced signaling through phosphorylation in disease development and progression.
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Hillary, V. Edwin, and S. Antony Ceasar. "Application of CRISPR/Cas9 Genome Editing System in Cereal Crops." Open Biotechnology Journal 13, no. 1 (2019): 173–79. http://dx.doi.org/10.2174/1874070701913010173.
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Recent developments in targeted genome editing accelerated genetic research and opened new potentials to improve the crops for better yields and quality. Genome editing techniques like Zinc Finger Nucleases (ZFN) and Transcription Activator-Like Effector Nucleases (TALENs) have been accustomed to target any gene of interest. However, these systems have some drawbacks as they are very expensive and time consuming with labor-intensive protein construction protocol. A new era of genome editing technology has a user-friendly tool which is termed as Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-CRISPR associated protein9 (Cas9), is an RNA based genome editing system involving a simple and cost-effective design of constructs. CRISPR/Cas9 system has been successfully applied in diverse crops for various genome editing approaches. In this review, we highlight the application of the CRISPR/Cas9 system in cereal crops including rice, wheat, maize, and sorghum to improve these crops for better yield and quality. Since cereal crops supply a major source of food to world populations, their improvement using recent genome editing tools like CRISPR/Cas9 is timely and crucial. The genome editing of cereal crops using the CRISPR/Cas9 system would help to overcome the adverse effects of agriculture and may aid in conserving food security in developing countries.
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Park, Ki-Eun, and Bhanu Prakash V. L. Telugu. "Role of stem cells in large animal genetic engineering in the TALENs–CRISPR era." Reproduction, Fertility and Development 26, no. 1 (2014): 65. http://dx.doi.org/10.1071/rd13258.
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The establishment of embryonic stem cells (ESCs) and gene targeting technologies in mice has revolutionised the field of genetics. The relative ease with which genes can be knocked out, and exogenous sequences introduced, has allowed the mouse to become the prime model for deciphering the genetic code. Not surprisingly, the lack of authentic ESCs has hampered the livestock genetics field and has forced animal scientists into adapting alternative technologies for genetic engineering. The recent discovery of the creation of induced pluripotent stem cells (iPSCs) by upregulation of a handful of reprogramming genes has offered renewed enthusiasm to animal geneticists. However, much like ESCs, establishing authentic iPSCs from the domestic animals is still beset with problems, including (but not limited to) the persistent expression of reprogramming genes and the lack of proven potential for differentiation into target cell types both in vitro and in vivo. Site-specific nucleases comprised of zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs) and clustered regulated interspaced short palindromic repeats (CRISPRs) emerged as powerful genetic tools for precisely editing the genome, usurping the need for ESC-based genetic modifications even in the mouse. In this article, in the aftermath of these powerful genome editing technologies, the role of pluripotent stem cells in livestock genetics is discussed.
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Negrescu, Andreea-Mariana, Madalina-Georgiana Necula, Adi Gebaur та ін. "In Vitro Macrophage Immunomodulation by Poly(ε-caprolactone) Based-Coated AZ31 Mg Alloy". International Journal of Molecular Sciences 22, № 2 (2021): 909. http://dx.doi.org/10.3390/ijms22020909.
Texte intégralRésumé :
Due to its excellent bone-like mechanical properties and non-toxicity, magnesium (Mg) and its alloys have attracted great interest as biomaterials for orthopaedic applications. However, their fast degradation rate in physiological environments leads to an acute inflammatory response, restricting their use as biodegradable metallic implants. Endowing Mg-based biomaterials with immunomodulatory properties can help trigger a desired immune response capable of supporting a favorable healing process. In this study, electrospun poly(ε-caprolactone) (PCL) fibers loaded with coumarin (CM) and/or zinc oxide nanoparticles (ZnO) were used to coat the commercial AZ31 Mg alloy as single and combined formulas, and their effects on the macrophage inflammatory response and osteoclastogenic process were investigated by indirect contact studies. Likewise, the capacity of the analyzed samples to generate reactive oxygen species (ROS) has been investigated. The data obtained by attenuated total reflection Fourier-transform infrared (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS) analyses indicate that AZ31 alloy was perfectly coated with the PCL fibers loaded with CM and ZnO, which had an important influence on tuning the release of the active ingredient. Furthermore, in terms of degradation in phosphate-buffered saline (PBS) solution, the PCL-ZnO- and secondary PCL-CM-ZnO-coated samples exhibited the best corrosion behaviour. The in vitro results showed the PCL-CM-ZnO and, to a lower extent, PCL-ZnO coated sample exhibited the best behaviour in terms of inflammatory response and receptor activator of nuclear factor kappa-B ligand (RANKL)-mediated differentiation of RAW 264.7 macrophages into osteoclasts. Altogether, the results obtained suggest that the coating of Mg alloys with fibrous PCL containing CM and/or ZnO can constitute a feasible strategy for biomedical applications.
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Ohadi, Sara, Amar Godar, John Madsen, and Kassim Al-Khatib. "Response of Rice Algal Assemblage to Fertilizer and Chemical Application: Implications for Early Algal Bloom Management." Agronomy 11, no. 3 (2021): 542. http://dx.doi.org/10.3390/agronomy11030542.
Texte intégralRésumé :
California water-seeded rice is challenged with the rapid growth of nuisance algae at the beginning of the season. Rice seedlings entangled in the algal mat may not be established, causing empty rice patches in the field. Two separate studies were conducted to (1) evaluate the effect of nutrients (nitrogen and phosphorous) on algae growth, and (2) test various chemical options to control algae. Both studies utilized 19 L buckets inoculated with algae collected from a rice field. In the nutrient evaluation study, 36 nutrient treatments obtained from a combination of nitrogen (0, 60, 120, 180, 240 and 300 kg ha−1) and phosphorous (0, 20, 40, 60, 80 and 100 kg ha−1) rates were applied into the buckets, while eight chemicals with potential for algae control (two Protox inhibitor herbicides, four copper-based compounds, hydrogen peroxide, Zinc sulfate) were tested in the second experiment. In addition, a yeast extract-based surfactant (AMP activator) was tested in combination with a chelated copper formulation (Algimycin) and hydrogen peroxide. The studies had a completely randomized design with three replicates and each study was repeated two times. The result from the nutrient evaluation study showed that nitrogen and phosphorus can independently cause change in algae growth as reflected in the fresh and dry biomass. Moreover, low rates of either nitrogen or phosphorus resulted in a rapid increase in algae biomass and water chlorophyll a content, whereas the growth of algae declined at higher rates of applied fertilizer. Among tested chemicals in the second experiment, the chelated formulation of copper (Algimycin PWF) controlled algae (85%) better than the ethanolamine formulations [Cutrine-Ultra (70%) and Cutrine-Plus (52%)] and elemental copper (crystalline copper sulfate) (75%). Protox herbicides (oxyfluorfen and oxadiazon) were able to control algae by up to 70%. Hydrogen peroxide controlled algae by 50% and its efficacy dropped dramatically five days after treatment (DAT). Zinc sulfate was only effective at 1 DAT and algae recovered rapidly after that. Combining fertilizer management practices with chemical options will enable us toward an integrative approach for early algal bloom in the rice cropping system.
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Inukai, T., T. Inaba, T. Yoshihara, and A. T. Look. "Cell transformation mediated by homodimeric E2A-HLF transcription factors." Molecular and Cellular Biology 17, no. 3 (1997): 1417–24. http://dx.doi.org/10.1128/mcb.17.3.1417.
Texte intégralRésumé :
The E2A-HLF fusion gene, created by the t(17;19)(q22;p13) chromosomal translocation in pro-B lymphocytes, encodes an oncogenic protein in which the E2A trans-activation domain is linked to the DNA-binding and protein dimerization domain of hepatic leukemia factor (HLF), a member of the proline- and acidic amino acid-rich (PAR) subfamily of bZIP transcription factors. This fusion product binds to its DNA recognition site not only as a homodimer but also as a heterodimer with HLF and two other members of the PAR bZIP subfamily, thyrotroph embryonic factor (TEF) and albumin promoter D-box binding protein (DBP). Thus, E2A-HLF could transform cells by direct regulation of downstream target genes, acting through homodimeric or heterodimeric complexes, or by sequestering normal PAR proteins into nonfunctional heterocomplexes (dominant-negative interference). To distinguish among these models, we constructed mutant E2A-HLF proteins in which the leucine zipper domain of HLF was extended by one helical turn or altered in critical charged amino acids, enabling the chimera to bind to DNA as a homodimer but not as a heterodimer with HLF or other PAR proteins. When introduced into NIH 3T3 cells in a zinc-inducible vector, each of these mutants induced anchorage-independent growth as efficiently as unaltered E2A-HLF, indicating that the chimeric oncoprotein can transform cells in its homodimeric form. Transformation also depended on an intact E2A activator region, providing further support for a gain-of-function contribution to oncogenesis rather than one based on a dominant-interfering or dominant-negative mechanism. Thus, the tumorigenic effects of E2A-HLF and its mutant forms in NIH 3T3 cells favor a straightforward model in which E2A-HLF homodimers bind directly to promoter/enhancer elements of downstream target genes and alter their patterns of expression in early B-cell progenitors.
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Jamaludin, Liyana, Rafiza Abd Razak, Mohd Mustafa Al Bakri Abdullah, et al. "Solid-to-Liquid Ratio Influenced on Adhesion Strength of Metakaolin Geopolymer Coating Paste Added Photocatalyst Materials." Coatings 13, no. 2 (2023): 236. http://dx.doi.org/10.3390/coatings13020236.
Texte intégralRésumé :
Coating materials are used on surfaces such as steel and ceramic to offer protection, corrosion resistance, wear and erosion resistance, a thermal barrier, or aesthetics. Although organic coating materials such as epoxy resins, silane, and acrylic are widely used, there are restrictions and drawbacks associated with their use, including the ease with which cracking, hazardous and harmful human health and environment, peeling, and deterioration occur. Organic matrices also have the capacity to release vapor pressure, which can lead to the delamination of coatings. Geopolymer coating materials offer an environmentally friendly solution to this concern to encourage sustainable growth. The simplicity with which geopolymers can be synthesized and their low emission of greenhouse gases such as CO2, SO2, and NOx are advantages of geopolymers. The advent of geopolymer coatings with photocatalytic properties is advantageous for the decomposition of pollution and self-cleaning properties. The aim of this paper is to study the optimum solid-to-liquid ratio of metakaolin geopolymer paste added TiO2 and ZnO by adhesion strength. Through iterative mixture optimization, we investigated the effects of different design parameters on the performance of a metakaolin-based geopolymer as a coating material. The assessed material was a metakaolin which was activated by an alkali activator (a mixture of sodium hydroxide and sodium silicate), with the addition of titanium dioxide and zinc oxide as photocatalyst substances. Varying proportions of solid-to-liquid ratio were tested to optimize the best mix proportion related to the coating application. Adhesion analyses of geopolymer coating paste were evaluated after 7 days. According to the findings, the optimal parameters for metakaolin geopolymer coating material are 0.6 solid-to-liquid ratios with the highest adhesion strength (19 MPa) that is suitable as coating material and enhanced the properties of geopolymer.
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Yang, Zhenyun, Takako Kondo, Cara s. Voorhorst, et al. "Increased C-Jun and Reduced GATA2 Expression Promotes Aberrant Monocytic Differentiation and Expansion Induced by Activating PTPN11 Mutants." Blood 112, no. 11 (2008): 3720. http://dx.doi.org/10.1182/blood.v112.11.3720.3720.
Texte intégralRésumé :
Abstract Juvenile myelomonocytic leukemia (JMML) is a myeloproliferative disorder characterized by overproduction of myelomonocytic cells. Activating mutations of PTPN11, which encodes the protein tyrosine phosphatase, Shp2, are found in 35% of JMML patients. Murine bone marrow low density mononuclear cells (LDMNCs) expressing activating Shp2 mutants preferentially undergo myelomonocytic differentiation and expansion despite being subjected to conditions that normally support only mast cell development. Evaluation of hematopoietic cell-specific transcription factor expression using quantitative RT-PCR indicates equal expression of PU.1 in mutant Shp2- and WT Shp2-expressing hematopoietic progenitors; however, GATA2 expression is substantially reduced and c-Jun expression is increased in mutant Shp2-expressing progenitors. Based on these findings, we hypothesized that mutant Shp2-induced Ras hyperactivation produces constitutive c-Jun expression permitting, as a co-activator of PU.1, excessive monocytic differentiation and reduced GATA2 expression. As a corollary, we hypothesized that ectopic expression of GATA2, but not of GATA2 lacking the C-terminal zinc finger (amino acids 330 – 407, DGATA2), which is needed to compete with c-Jun for binding to PU.1, would normalize mutant Shp2-induced monocytic differentiation and expansion. To examine this hypothesis, we utilized retroviral co-transduction of bone marrow Lin-enriched cells to generate six experimental groups: pMIEG3-Shp-2WT plus pCD4 (empty vector); pMIEG3-Shp2WT plus pCD4-GATA2; pMIEG3-Shp2WT plus pCD4-ΔGATA2; pMIEG3-Shp-2E76K plus pCD4; pMIEG3-Shp-2E76K plus pCD4-GATA2; pMIEG3-Shp-2E76K plus pCD4-ΔGATA2. Cells were stained with anti-human CD4 conjugated to allophycocyanin (APC), sorted for EGFP+APC+ cells, and plated into progenitor assays. Colonies were scored for colony forming unit (CFU)-granulocyte-macrophage (GM), monocyte (M), granulocyte (G), and granulocyte-erythroid-monocyte-megakaryocyte (GEMM). As predicted, cells co-transduced with activating Shp2 mutant E76K and a secondary empty vector produced significantly more CFU-M than cells expressing WT Shp2. Upon co-transduction with GATA2, the number of CFU-M generated from E76K-expressing cells was significantly reduced. In contrast, cotransduction of ΔGATA2 lacking the C-terminal zinc finger failed to normalize the number of CFU-M produced by E76K-expressing cells. Mechanistically, we reasoned that if the c-Jun-PU.1 interaction contributes to the mutant Shp2-induced aberrant monocytic differentiation, we would observe increased expression directed by the macrophage colony-stimulating factor receptor (MCSFR) promoter, originally characterized to be activated by PU.1 and co-activator c-Jun. Consistently, MCSFR promoter-directed luciferase expression exhibited higher levels in NIH3T3 cells expressing Shp2E76K compared to those expressing WT Shp2. Furthermore, co-immunoprecipitation assays using nuclear extracts demonstrate increased c-Jun-PU.1 complexes in mutant Shp2-expressing hematopoietic progenitors, while chromatin immunoprecipitation assays demonstrate an increased association of the c-Jun-PU.1 complex at the MCSFR promoter. Moreover, CD34+ JMML progenitors express significantly higher levels of c-JUN than CD34+ cord blood progenitors from healthy newborns, substantiating the disease relevance of these mechanistic findings. These data suggest that one fundamental sequela of Ras hyperactivation in mutant Shp2-expressing cells is elevated c-Jun expression and an increased c-Jun-PU.1 interaction promoting monocytic differentiation and, thus, overproduction of myelomonocytic cells, the hallmark of JMML. These findings imply that pharmaceutical interventions that inhibit c-Jun expression or function could theoretically inhibit mutant Shp2-induced monocytic differentiation and, thus, serve as a novel approach for treatment of JMML.