A Step-by-Step Guide for the Production of Recombinant Fluorescent TAT-HA-Tagged Proteins and their Transduction into Mammalian Cells.

Investigating the function of target proteins for functional prospection or therapeutic applications typically requires the production and purification of recombinant proteins. The fusion of these proteins with tag peptides and fluorescently derived proteins allows the monitoring of candidate proteins using SDS-PAGE coupled with western blotting and fluorescent microscopy, respectively. However, protein engineering poses a significant challenge for many researchers. In this protocol, we describe step-by-step the engineering of a recombinant protein with various tags: TAT-HA (trans-activator of transduction-hemagglutinin), 6×His and EGFP (enhanced green fluorescent protein) or mCherry. Fusion proteins are produced in E. coli BL21(DE3) cells and purified by immobilized metal affinity chromatography (IMAC) using a Ni-nitrilotriacetic acid (NTA) column. Then, tagged recombinant proteins are introduced into cultured animal cells by using the penetrating peptide TAT-HA. Here, we present a thorough protocol providing a detailed guide encompassing every critical step from plasmid DNA molecular assembly to protein expression and subsequent purification and outlines the conditions necessary for protein transduction technology into animal cells in a comprehensive manner. We believe that this protocol will be a valuable resource for researchers seeking an exhaustive, step-by-step guide for the successful production and purification of recombinant proteins and their entry by transduction within living cells. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: DNA cloning, molecular assembly strategies, and protein production Basic Protocol 2: Protein purification Basic Protocol 3: Protein transduction in mammalian cells.

Posicionamiento conceptual para la identificación de fenotipos de obesidad al inicio de la gestación / Conceptual positioning for the obesity phenotypes identification at the beginning of pregnancy

Los fenotipos de obesidad se presentan en individuos con igual índice de masa corporal que tienen diferentes perfiles metabólicos y pronósticos de salud. Su presencia desde etapas tempranas de la vida hace que incremente la probabilidad de que una mujer arribe al embarazo con estas características, por lo que es necesario promover un posicionamiento conceptual para su identificación. En gestantes normopeso, se sugiere identificar el fenotipo normopeso obeso cuando presenta valor igual o superior al 30 por ciento de la grasa corporal o al 90 percentil de la suma de pliegues cutáneos tricipital y subescapular. De ellas, las que tengan valores iguales o superiores al 75 percentil del índice de adiposidad visceral y del producto de acumulación de los lípidos, se consideran normopeso metabólicamente obesas. En las obesas se propone el uso de los criterios que definen al síndrome metabólico en mujeres, con valores ajustados para gestantes, para identificar la salud metabólica. Los argumentos expuestos demuestran lo idóneo de estratificar el riesgo metabólico al inicio de la gestación al clasificarlas en fenotipos de obesidad, mediante indicadores antropométricos, bioquímicos y clínicos que identifican al síndrome metabólico(AU)

The obesity phenotypes settle down in individuals with equal body mass index that present different metabolic profiles and health prognosis. Its presence from early stages of life increases the probability that women get pregnant with this characteristic, so it is considered necessary to promote a conceptual position for its identification at the beginning of pregnancy. In normal-weight pregnant woman, we propose to use the value of 30 percent or the 90th percentile of the sum of the triceps and subescapularis skinfold to define obese normal-weight phenotype. Of these, those with values equal to or greater than the 75th percentile of visceral adiposity index and the lipids accumulation product would be considered obese metabolically normal-weight. In obese pregnant woman the use of the criteria that define metabolic syndrome in women, is proposed to identify the metabolic health. The exposed theoretical foundations demonstrate the suitability of stratifying metabolic risk at the beginning of pregnancy by classifying it into obesity phenotypes, through anthropometric, biochemical, and clinical indicators(AU)

Development of tobacco rattle virus-based platform for dual heterologous gene expression and CRISPR/Cas reagent delivery.

A large number of viral delivery systems have been developed for characterizing functional genes and producing heterologous recombinant proteins in plants, and but most of them are unable to co-express two fusion-free foreign proteins in the whole plant for extended periods of time. In this study, we modified tobacco rattle virus (TRV) as a TRVe dual delivery vector, using the strategy of gene substitution. The reconstructed TRVe had the capability to simultaneously produce two fusion-free foreign proteins at the whole level of Nicotiana benthamiana, and maintained the genetic stability for the insert of double foreign genes. Moreover, TRVe allowed systemic expression of two foreign proteins with the total lengths up to ∼900 aa residues. In addition, Cas12a protein and crRNA were delivered by the TRVe expression system for site-directed editing of genomic DNA in N. benthamiana 16c line constitutively expressing green fluorescent protein (GFP). Taker together, the TRV-based delivery system will be a simple and powerful means to rapidly co-express two non-fused foreign proteins at the whole level and facilitate functional genomics studies in plants.

Cytoplasmic Production of Nanobodies and Nanobody-Based Reagents by Co-Expression of Sulfhydryl Oxidase and DsbC Isomerase.

Nanobodies are stable molecules that can often fold correctly even in the absence of the disulfide bond(s) that stabilize their three-dimensional conformation. Nevertheless, some nanobodies require the formation of disulfide bonds, and therefore they are commonly expressed from vectors that promote their secretion into the oxidizing environment of the Escherichia coli periplasm. As an alternative, the bacterial cytoplasm can be an effective compartment for producing correctly folded nanobodies when sulfhydryl oxidase and disulfide-bond isomerase activities are co-expressed from a recombinant vector. The larger volume and wider chaperone/foldase availability of the cytoplasm enable the achievement of high yields of both nanobodies and nanobody-tag fusions, independently of their redox requirements. Among other examples, the protocol described here was used to successfully produce nanobody fusions with fluorescent proteins that do not fold correctly in the periplasm, nanobodies with Fc domains, and nanobodies containing free cysteine tags.

Validation of a Fast and Simple HPLC-UV Method for the Quantification of Adenosine Phosphates in Human Bronchial Epithelial Cells.

A new HPLC method for the simultaneous quantitative analysis of adenosine triphosphate (ATP), adenosine diphosphate (ADP), and adenosine monophosphate (AMP) was developed and validated. ATP, ADP, and AMP were extracted from human bronchial epithelial cells with a rapid extraction procedure and separated with a C18 column (3 × 150 mm, 2.7 µm) using isocratic elution with a mobile phase consisting of 50 mM of potassium hydrogen phosphate (pH 6.80). The absorbance was monitored at 254 nm. The calibration curves were linear in 0.2 to 10 µM, selective, precise, and accurate. This method allowed us to quantify the nucleotides from two cell models: differentiated NHBE primary cells grown at the air-liquid interface (ALI) and BEAS-2B cell line. Our study highlighted the development of a sensitive, simple, and green analytical method that is faster and less expensive than other existing methods to measure ATP, ADP, and AMP and can be carried out on 2D and 3D cell models.

Development of fluorescent-labeled trapping reagents based on cysteine to detect soft and hard electrophilic reactive metabolites.

Trapping assays are conducted at lead optimization stages to detect reactive metabolites (RMs) that can contribute to drug toxicity. The commonly used dansyl glutathione (dGSH) provides a sensitive analysis owing to the fluorescent label, however, it captures only soft electrophilic RMs. TRs for hard electrophilic RMs, few of which are labeled fluorescently, can detect hard electrophilic aldehydes only by forming unstable imine derivatives. In this study, we aimed to develop novel fluorescently labeled TRs that detect both soft and hard electrophilic RMs and form stable ring structures with aldehydes. We designed four dansylated TRs based on cysteine, which has both soft and hard nucleophilic groups. To evaluate the reactivity of the TRs, we incubated them with several substrates and found that one of the TRs (CysGlu-Dan) detected all the soft and hard electrophilic RMs. We also examined the inhibition potential of each TR for seven major CYPs involved in drug metabolism and found that CysGlu-Dan showed an inhibitory profile similar to that of dGSH. In conclusion, CysGlu-Dan can be used to evaluate the risk of RMs in drug discovery.

[Age-related features of the relationship between the content of vascular endothelial growth factor and indicators of lipid metabolism and extracellular matrix metabolism in men in the European part of the Russian Arctic.]

The content of vascular endothelial growth factor-A (VEGF-A) in blood plasma and its relationship with lipid and extracellular matrix metabolism in working-aged men (19-69 years), living and working in the European part of the Arctic zone of the Russian Federation (Russian Arctic), were studied. No age dependence of the plasma VEGF-A content was found. The correlation analysis, performed in different age groups, revealed significant associations of VEGF-A level with lipid parameters (CS, LDL-C, Apo B, atherogenicity coefficient, Apo B /Apo A1 ratio) and extracellular matrix metabolism (blood TIMP-4, MMP-2, MMP-3, MMP-9, hyaluronan, total and peptide-bound hydroxyproline, glycosaminoglycans). The established correlations indicate the formation of relationships between angiogenesis, atherogenesis and fibrosis at a specific period of life of northerners in the Russian Arctic.

Bioinspired Thiophosphorodichloridate Reagents for Chemoselective Histidine Bioconjugation.

Site-selective bioconjugation to native protein residues is a powerful tool for protein functionalization, with cysteine and lysine side chains being the most common points for attachment owing to their high nucleophilicity. We now report a strategy for histidine modification using thiophosphorodichloridate reagents that mimic post-translational histidine phosphorylation, enabling fast and selective labeling of protein histidines under mild conditions where various payloads can be introduced via copper-assisted alkyne-azide cycloaddition (CuAAC) chemistry. We establish that these reagents are particularly effective at covalent modification of His-tags, which are common motifs to facilitate protein purification, as illustrated by selective attachment of polyarginine cargoes to enhance the uptake of proteins into living cells. This work provides a starting point for probing and enhancing protein function using histidine-directed chemistry.

Iridium-based probe for luminescent nitric oxide monitoring in live cells.

Nitric oxide (NO) is an intra- and extracellular messenger with important functions during human physiology process. A long-lived luminescent iridium(III) complex probe 1 has been designed and synthesized for the monitoring of NO controllably released from sodium nitroprusside (SNP). Probe 1 displayed a 15-fold switch-on luminescence in the presence of SNP at 580 nm. The probe exhibited a linear response towards SNP between 5 to 25 µM with detection limit at 0.18 µM. Importantly, the luminescent switch-on detection of NO in HeLa cells was demonstrated. Overall, complex 1 has the potential to be applied for NO tracing in complicated cellular environment.

Starch-enriched diet modulates the glucidic profile in the rat colonic mucosa.

PURPOSE: The protective function of the intestinal mucosa largely depends on carbohydrate moieties that as a part of glycoproteins and glycolipids form the epithelial glycocalyx or are secreted as mucins. Modifications of their expression can be induced by an altered intestinal microenvironment and have been associated with inflammatory disorders and colorectal cancer. Given the influence of dietary factors on the gut ecosystem, here we have investigated whether a long term feeding on a starch-rich diet can modulate the glucidic profile in the colonic mucosa of rats. METHODS: Animals were divided into two groups and maintained for 9 months at different diets: one group was fed a standard diet, the second was fed a starch-enriched diet. Samples of colonic mucosa, divided in proximal and distal portions, were processed for microscopic analysis. Conventional stainings and lectin histochemistry were applied to identify acidic glycoconjugates and specific sugar residues in oligosaccharide chains, respectively. Some lectins were applied on adjacent sections after sialidase/fucosidase digestion, deacetylation, and oxidation to characterize either terminal dimers or sialic acid acetylation. RESULTS: An increase in sulfomucins was found to be associated with the starch-enriched diet that affected also the expression of several sugar residues as well as fucosylated and sialylated sequences in both proximal and distal colon. CONCLUSIONS: Although the mechanisms leading to such a modulation are at present unknown, either an altered intestinal microbiota or a dysregulation of glycosylation patterns might be responsible for the types and distribution of changes in the glucidic profile here observed.

Acanthamoeba (T4) trophozoites cross the MDCK epithelium without cell damage but increase paracellular permeability and transepithelial resistance by modifying tight junction composition.

Free-living amoebae of the genus Acanthamoeba are protozoa ubiquitously found in nature. Some species of the genus are potentially pathogenic for humans provoking keratitis in healthy individuals, often in contact lens wearers and opportunistic infections such as pneumonitis, fatal granulomatous encephalitis and skin infections, particularly in immunocompromised individuals. The pathogenic mechanisms of these amoebae are poorly understood, however it had been suggested that contact dependent mechanisms are important during invasion, regardless of the epithelia type, since amoebae penetrate epithelia separating tight junction (TJ). This study was undertaken to determine whether Acanthamoeba sp. (T4) damages the barrier function of the TJ in MDCK epithelial monolayers. Actin cytoskeleton staining and electron microscopy analyses were performed; paracellular permeability and TJ sealing were evaluated by apicobasolateral diffusion of ruthenium red and transepithelial resistance (TER) measurements; immunofluorescence and Western blot assays were performed to locate and estimate expression of TJ protein claudins 2 (Cldn2) and 4 (Cldn4). The results show that Acanthamoeba sp. crosses the MDCK monolayer without altering the actin cytoskeleton or the morphology of the cells. When trophozoites or conditioned medium interact with the monolayer, paracellular diffusion of ruthenium red increases. After 6 h, the amoebae, but not their conditioned medium, increase the TER, and Cldn2 is removed from the TJ, and its overall content in the cells diminishes, while Cldn4 is targeted to the TJ without changing its expression level. In conclusion Acanthamoeba (T4) crosses MDCK monolayer without damaging the cells, increasing permeability and TER through Cldn2 degradation, and redirecting Cldn4 to TJ. These results strongly suggest that contact-dependent mechanisms are relevant during amoebae invasion.

Assessment of in vitro killing assays for detecting praziquantel-induced death in Posthodiplostomum minimum metacercariae.

Control of parasitic infections may be achieved by eliminating developmental stages present within intermediate hosts, thereby disrupting the parasite life cycle. For several trematodes relevant to human and veterinary medicine, this involves targeting the metacercarial stage found in fish intermediate hosts. Treatment of fish with praziquantel is one potential approach for targeting the metacercaria stage. To date, studies investigating praziquantel-induced metacercarial death in fish rely on counting parasites and visually assessing morphology or movement. In this study, we investigate quantitative methods for detecting praziquantel-induced death using a Posthodiplostomum minimum model. Our results revealed that propidium iodide staining accurately identified praziquantel-induced death and the level of staining was proportional to the concentration of praziquantel. In contrast, detection of ATP, resazurin metabolism, and trypan blue staining were poor indicators of metacercarial death. The propidium iodide method offers an advantage over simple visualization of parasite movement and could be used to determine EC50 values relevant for comparison of praziquantel sensitivity or resistance.

High-Throughput Spheroid Screens Using Volume, Resazurin Reduction, and Acid Phosphatase Activity.

Mainstream adoption of physiologically relevant three-dimensional models has been slow in the last 50 years due to long, manual protocols with poor reproducibility, high price, and closed commercial platforms. This chapter describes high-throughput, low-cost, open methods for spheroid viability assessment which use readily available reagents and open-source software to analyze spheroid volume, metabolism, and enzymatic activity. We provide two ImageJ macros for automated spheroid size determination-for both single images and images in stacks. We also share an Excel template spreadsheet allowing users to rapidly process spheroid size data, analyze plate uniformity (such as edge effects and systematic seeding errors), detect outliers, and calculate dose-response. The methods would be useful to researchers in preclinical and translational research planning to move away from simplistic monolayer studies and explore 3D spheroid screens for drug safety and efficacy without substantial investment in money or time.

Imaging Probes and Modalities for the Study of Solute Carrier O (SLCO)-Transport Function In Vivo.

Transporters of the solute carrier O (SLCO) family, former organic anion-transporting polypeptides, are now recognized as key players in pharmacokinetics. Imaging is increasingly regarded as a relevant method to elucidate and decipher the intrinsic role of SLCO in controlling drug disposition in plasma and tissues. Current research in this representative field of translational research is based on different imaging modalities including nuclear imaging, such as single-photon emission computed tomography or positron emission tomography, and magnetic resonance imaging. Imaging modalities can be compared in terms of sensitivity, quantitative properties, spatial resolution, variety of ligands, and radiation exposure. All these approaches rely on the use of SLCO substrates that are detected using corresponding modalities. The present review aims at reporting and comparing the imaging probes that have been proposed to study SLCO-transport function, in terms of in vitro specificity, in vivo behavior, and clinical validation.

In-situ protein determination to monitor contamination in a centrifugal partition chromatograph.

Centrifugal partition chromatography (CPC) works with biphasic liquid systems including aqueous two-phase systems. Metallic rotors are able to retain an aqueous stationary phase able to purify proteins. But the adhesion of proteins to solid surface may pose a cross-contamination risk during downstream processes. So it is of utmost importance to ensure the cleanliness of the equipment and detect possible protein contamination in a timely manner. Thereby, a direct method that allows the determination of the effective presence of proteins and the extent of contamination in the metallic CPC rotors was developed. This in-situ method is derived from the Amino Density Estimation by Colorimetric Assay (ADECA) which is based on the affinity of a dye, Coomassie Brillant Blue (CBB), with protonated N+ groups of the proteins. In this paper, the ADECA method was developed dynamically, on a 25 mL stainless-steel rotor with various extents of protein contaminations using bovine serum albumin (BSA) as a fouling model. The eluted CBB dye was quantified and found to respond linearly to BSA contamination up to 70 mg injected. Limits of detection and quantification were recorded as 0.9 mg and 3.1 mg, respectively. While the non-specific interactions between the dye and the rotor cannot currently be neglected, this method allows for in situ determination of proteins contamination and should contribute to the development of CPC as a separation tool in protein purification processes.

High background in Luminex® assay for HLA antibody screening: Interest of Adsorb Out™.

INTRODUCTION: The Luminex® technology has become an integral component of clinical decision-making and diagnosis of transplanted organ rejection. Despite the superior sensibility of this technology, it is not completely problem free. We have observed in these bead-based assays that sera of some patients give a high negative control bead (NC) value which makes assessing HLA antibodies difficult. Treatment of sera by the Adsorb Out™ reagent may reduce the high background. In this study, we want to evaluate the effect of the Adsorb Out™ on the NC's MFI value by comparing treated and untreated patients' sera. METHODS: HLA antibody screening was performed on 3011 sera. These sera came from patients awaiting and undergoing renal transplant from different Moroccan hospitals. The sera were analyzed using the standard protocol for Luminex® antibody screening. Sera with high NC's value has been pre-incubated by the Adsorb Out™, and analyzed on Luminex®. RESULTS: 3% of studied samples have high NC's value. The Adsorb Out™ decreases the NC's value and brings it back to a normal range in 62.2% treated sera. It has no effect in 12.3%. The Adsorb Out™ effect depends only of NC's value, independently to age, storage date, sex and immunization. CONCLUSION: The Adsorb Out™ reagent has an important effect in decreasing NC value of sera. However, it has no effect in some patient's sera. In these cases we could try another treatment, as EDTA, DTT. The non-specific binding may be caused by multiple patient-specific factors, it would be important to search correlation between them and NC's values.

Ischemia triggered ATP release through Pannexin-1 channel by myocardial cells activates sympathetic fibers.

The cardiovascular system is extensively innervated by the autonomic nervous system, and the autonomic modulation including sympathetic innervation is crucial to the function of heart during normal and ischemic conditions. Severe myocardial ischemia could cause acute myocardial infarction, which is one of the leading diseases in the world. Thus studying the sympathetic modulation during ischemia could reduce the probability of myocardial infarction and further heart failure. The neurotransmitter ATP is released by myocardial cells during ischemia; however, the effect of ATP release remains elusive. We examined whether ATP released during ischemia functions as a neurotransmitter that activates sympathetic nerve in the heart. A novel technique of recording the sympathetic fiber calcium imaging in mouse cardiac tissue slices was used. We have applied the Cre/loxP system to specifically express GCaMP3, a genetically encoded calcium indicator, in the sympathetic nerve. Using this technique, we found that ATP released by myocardial cells through Pannexin-1 channel during ischemia could evoke calcium responses in cardiac sympathetic nerve fibers. Our study provides a new approach to study the cell and nerve interaction in the cardiac system, as well as a new understanding of ATP function during ischemia.

Analysis of the intra- and intertumoral heterogeneity of hypoxia in pancreatic cancer patients receiving the nitroimidazole tracer pimonidazole.

BACKGROUND: Hypoxia is thought to be an adverse feature of pancreatic cancer, but direct measurement in patients is technically challenging. To address this, we characterised the intra/interpatient heterogeneity of hypoxia in surgical specimens from patients who received the 2-nitroimidazole tracer pimonidazole pre-operatively. METHODS: Pimondazole was given intravenously 16-20 h before pancreatectomy, and the extent and intratumoral heterogeneity of hypoxia determined by image analysis applied to multiple tissue blocks stained by immunohistochemistry. Intra/interpatient heterogeneity was estimated by variance component analysis. RESULTS: Pimonidazole staining was analysed in 10 tumours. The extent of labelling varied amongst patients (0-26%), with a broader range of hypoxia in the epithelial (1-39%) compared with the stromal (1-13%) compartments. Variance component analysis demonstrated greater inter- than intrapatient variability of hypoxia, and that multiple (4-5) tumour sections are required to provide a consistent evaluation of its extent in individual tumours. CONCLUSIONS: There is significant intra- and intertumoral heterogeneity of hypoxia in pancreatic cancers, and these do not appear to be generally more hypoxic than other cancer types. This study establishes the feasibility to assess hypoxia in pancreatic cancer patients using pimonidazole, but questions the reliability of measurements made using a single tissue section.

A novel method for measuring TBAb activity in TSAb- and TBAb-positive serum.

We reported a conversion assay in which thyroid blocking antibody (TBAb) function as thyroid stimulating antibody (TSAb). TBAb-bound porcine thyroid cells (PTC) were made by incubating TBAb(+) serum and PTC for 1 hour. When these TBAb-bound PTC were incubated 4 h with rabbit anti-human (h) IgG antibody (Ab), cAMP production was high, but when incubated with normal rabbit serum (NRS) cAMP production was low. TBAb-Mnoclonal Ab (MoAb) (KI-70) showed similar conversion. However, when TSAb-MoAb(M22) was assayed, anti-hIgG Ab-produced cAMP was lower than NRS-produced cAMP. When a mixture of M22 and KI-70 was assayed, anti-hIgG Ab-produced cAMP was higher than NRS. Thus, it is possible to determine existence of TBAb in TSAb(+)serum when anti-IgG Ab-produced cAMP is higher than NRS-produced cAMP. In this assay TBAb activity in TSAb(+)serum was scored as positive, gray zone and negative when the difference [anti-hIgG Ab-produced cAMP(%)-NRS-produced cAMP(%)] was >100%, 50-100% and <±50%, respectively. In TSAb(+)sera of Graves' patients with no treatment or anti-thyroid therapy, positive TBAb was 9% (3/33 )and 6.9% (5/72), and gray zone was 18 % (6/33) and 25% (18/72), respectively. A low prevelance of TBAb and low TBAb activity (<200% as cAMP) was found in these Graves' patients. A radioisotope treated Graves' patient showed existence of both TSAb and TBAb at 5 months (NRS, 800% cAMP and anti-IgGAb,1,350% cAMP), and highly positive TBAb (NRS, 180% cAMP and anti-hIgG Ab, 3,200% cAMP) at 30 months. This conversion assay is useful principally for TBAb determination but is also useful for TBAb determination in TSAb(+)serum.

Characterization and utility of phages bearing peptides with affinity to porcine reproductive and respiratory syndrome virus nsp7 protein.

High-affinity peptides to porcine reproductive and respiratory syndrome virus (PRRSV) nonstructural protein (nsp) 7 were identified using phage-display technology. Five 12-amino-acid peptide sequences were identified after six rounds of biopanning. A putative CD##WC motif was found in two different consensus peptides borne by phages 4 and 5. The peptides borne by phages 4, 5, and 6 were synthesized for subsequent experiments, according to the results of the binding assays. Immunofluorescence assay revealed that all these peptides recognized nsp7 in PRRSV-infected cells. Furthermore, the peptides demonstrated antiviral activities, with peptides 5 and 6 showing effective inhibition. Early peptide stimulation was associated with strong antiviral activity, and the inhibitory effects of the peptides were dose-dependent at 36 and 48 h post-infection. Peptide 5 was selected to detect the intracellular localization of nsp7 by confocal microscopy. This peptide had a similar effect to anti-nsp7 monoclonal antibody on nsp7. These results suggest that high-affinity peptides to PRRSV nsp7 could mimic the potential of nsp7 antibody as a diagnostic reagent for virus detection. Moreover, the peptides selected in this study represented a potentially effective antiviral candidate to inhibit PRRSV.