[Impedance Spectroscopy and Transcriptome Analysis of Choriocarcinoma BeWo b30 as a Model of Human Placenta].

Placenta is a highly specialized organ that is necessary for successful gestation. Several models of the placental barrier are used to study how it functions, including the transplacental transport of xenobiotics. One of these models, human choriocarcinoma cell line BeWo is widely used in vitro. Notably, cancerous BeWo cells form multilayer structures that normally are not found in the human placenta. Here, we aim to develop techniques suitable for monitoring BeWo b30 cells in culture. To assess the state of BeWo b30 cells growing on a membrane, we use impedance spectroscopy, which allows us to estimate the number of cell layers by the change in the electrical parameters of the biological system. In mature BeWo b30 cell cultures, we also note a significant increase in the expression of genes encoding metallothioneins (particularly, MT1B, MT1F, and MT2A) and syncytins (ERVW-1 and ERVFRD-1), which can be used as biomarkers reflecting the development of mature phenotypic characteristics, namely, trophoblastic invasion and formation of the syncytium.

Changes in the Metastatic Properties of MDA-MB-231 Cells after IGFBP6 Gene Knockdown Is Associated with Increased Expression of miRNA Genes Controlling INSR, IGF1R, and CCND1 Genes.

Metastatic cascade is associated with the process of epithelial-mesenchymal transition accompanied by changes in cell proliferation, migration, adhesion, and invasiveness mediated by the insulin-like growth factor (IGF) signal pathway. IGFBP6 protein binds IGF and prevents its interaction with receptors. IGFBP6 gene knockdown through RNA-interference inhibits cell migration and increased the rate of proliferation of breast cancer MDA-MB-231 cells. IGFBP6 knockdown cells are characterized by increased expression of MIR100 and MIRLET7A2 genes encoding hsa-miR-100-3p, hsa-miR-100-5p, hsa-let-7a-5p, and hsa-let-7a-2-3p miRNA. The target genes of these microRNAs are IGF2, IGF1R, INSR, and CCND1 associated with IGF signaling pathway and proliferative and migratory activity during the metastatic cascade. A significant decrease in the expression of INSR and CCND1 genes was demonstrated by PCR and microarray analysis.

Application of Impedance Spectroscopy for the Control of the Integrity of In Vitro Models of Barrier Tissues.

We compared available methods for monitoring the integrity of in vitro models of barrier tissues and studied the possibility of using impedance spectroscopy to solve this problem. It was demonstrated (theoretically and experimentally) that TEER measurements are not sufficiently sensitive to detect small defects in the cell barrier that significantly affect its permeability. For obtaining reliable results, it is necessary to set a sufficiently high threshold TEER, which leads to the loss of many intact samples. At the same time, impedance spectroscopy has all advantages of the classical method of measuring TEER (it is rapid and non-invasive method), while its application in combination with the methods of machine learning allows reliable detection of defects in the cell barrier.

Metabolic Reprogramming of Trophoblast Cells in Response to Hypoxia.

Hypoxia of trophoblast cells is an important regulator of normal development of the placenta. However, some pathological states associated with hypoxia, e.g. preeclampsia, impair the functions of placental cells. Oxyquinoline derivative inhibits HIF-prolyl hydroxylase by stabilizing HIF-1 transcription complex, thus modeling cell response to hypoxia. In human choriocarcinoma cells BeWo b30 (trophoblast model), oxyquinoline increased the expression of a core hypoxia response genes along with up-regulation of NOS3, PDK1, and BNIP3 genes and down-regulation of the PPARGC1B gene. These changes in the expression profile attest to activation of the metabolic cell reprogramming mechanisms aimed at reducing oxygen consumption by enabling the switch from aerobic to anaerobic glucose metabolism and the respective decrease in number of mitochondria. The possibility of practical use of the therapeutic properties of oxyquinoline derivatives is discussed.

Non-Invasive Evaluation of Extracellular Matrix Formation in the Intestinal Epithelium.

Differentiation of colorectal cancer Caco-2 cells was assessed using Affymetrix Human Gene 1.0 ST arrays and by the main electrical parameters measured by bioimpedance spectroscopy. Transepithelial electrical resistance (TEER) was maximum on day 7, then decreased by day 11, and remained stable. The baseline resistance was maximum on day 4, minimum on day 7, but then gradually increased over 2 weeks, which can be explained by the formation of the basement membrane components or the apical mucous layer. Caco-2 cells express components of laminin-111 and laminin-511. A synchronous increase in the expression of mucin 3 mRNA (MUC3A/MUC3B) and mucin 17 mRNA (MUC17) and reduced expression of miR-21 and miR-622 microRNA genes were observed. Possible use of the described approach for studying the formation of extracellular matrix is discussed.

[Expression of SLC30A10 and SLC23A3 Transporter mRNAs in Caco-2 Cells Correlates with an Increase in the Area of the Apical Membrane].

Drug bioavailability studies commonly employ in vitro barrier tissue models consisting of epithelial and endothelial cells. These experiments require that the cell barrier quality be assessed regularly, which is usually performed using various labeled substrates and/or evaluation of transepithelial (transendothelial) electrical resistance (TEER). This technique provides information on the integrity of the monolayer, but not on differentiation-induced changes in the cell morphology. The present work shows that impedance spectroscopy can be applied to monitor both the integrity of the monolayer and the morphological changes of Caco-2 cells. The growth kinetics of the apical membrane was determined by calculating the electrical capacitance of the cell monolayer. In the course of differentiation, the most pronounced changes in the expression levels were observed for the mRNAs that encode SLC30A10 and SLC23A3 transporters. Their increase correlated with an increase in the apical membrane area, indicating that SLC30A10 and SLC23A3 mRNA levels assessed by qRT-PCR may be employed as cell differentiation biomarkers in Caco-2 models.

New Fluorescent Reporter Systems for Evaluation of the Expression of E- and N-Cadherins.

During metastatic growth, cells of solid tumors undergo phenotypical changes related to epithelial-mesenchymal transition. Epithelial-mesenchymal transition is regarded as a potential target for prospective antitumor drugs. Fluorescent reporter systems for evaluation of the expression of markers of epithelial and mesenchymal status (E- and N-cadherins) were created. The described approaches can be used for creation of analogous reporter systems.

Expression of microRNA Genes MIR221, MIR222, and MIR181B1 Increases during Induction of Inflammation in the Endothelial Barrier Model.

We studied expression profile of microRNA and their target genes in human umbilical vein endothelial cells (HUVEC) during proinflammatory activation with TNFα. TNFα-induced activation of HUVEC was accompanied by a decrease in the expression of CDKN1B, HIST1H3D, and OIP5 genes that are the common target genes for mature microRNA encoded by MIR221, MIR222, and MIR181B1 genes, whose expression increases in activated cells. Proteins encoded by HIST1H3D and OIP5 genes are associated with chromatin compaction and cell cycle. Our results suggest that fetal endothelial microRNA can appear in the maternal blood during various pathological states, e.g., under conditions of preeclampsia.

TNFα-Induced Expression of Transport Protein Genes in HUVEC Cells Is Associated with Enhanced Expression of Transcription Factor Genes RELB and NFKB2 of the Non-Canonical NF-κB Pathway.

Endothelial HUVEC cells used as an in vitro model of the endothelial monolayer in placental barrier were activated by TNFα in a dose of 2 ng/ml for 24 h. Significant changes in the expression of genes of the SLC family transport protein were observed: an increase in the expression of SLC7A2, SLC12A2, SLC9B2, SLC25A37, SLC16A9, and SLC41A2 and a decrease in the expression of SLC40A1. These transporters participate in the transport of iron, magnesium, sodium, potassium, and chloride ions, protons, and amino acids. It was also found that SLC7A2, SLC12A2, SLC9B2, SLC25A37, and SLC41A2 genes have binding sites for transcriptional factor RelB that together with NFKB2 is the main effector of the non-canonical NF-κB pathway. The expression of RELB and NFKB2 genes was also significantly enhanced in TNFα-activated HUVEC cells, which can attest to the important role of the non-canonical NF-κB pathway in the regulation of gene expression of transport proteins in response to TNFα stimulation.

In Vitro Model for Studying of the Role of IGFBP6 Gene in Breast Cancer Metastasizing.

IGFBP6 gene plays an important role in the pathogenesis of breast cancer. In this work, we performed knockdown of IGFBP6 gene in MDA-MB-231 cells and obtained a stable cell line. Knockdown of IGFBP6 gene was confirmed by the real-time PCR. The influence of IGFBP6 gene on migration and proliferation of breast cancer cells was studied. Knockdown of IGFBP6 gene reduced migration activity of MDA-MB-231 cells and increased their proliferation rate. This in vitro cell model can be used for the further analysis of the role of IGFBP6 gene in the pathogenesis of breast cancer.

Role of IGFBP6 Protein in the Regulation of Epithelial-Mesenchymal Transition Genes.

Protein IGFBP6 plays an important role in the pathogenesis of many malignant tumors, including breast cancer. The relationship between IGFBP6 protein and the expression of genes associated with the epithelial-mesenchymal transition is studied. Gene IGFBP6 knockdown does not trigger the epithelial-mesenchymal transition in MDA-MB-231 cells, but modifies significantly the expression of many genes involved in this process. A decrease of IGFBP6 expression can involve a decrease in the expression of N-cadherin and transcription factor Slug.

Human Interleukin-2 and Hen Egg White Lysozyme: Screening for Bacteriolytic Activity against Various Bacterial Cells.

The bacteriolytic activity of interleukin-2 and hen egg white lysozyme against 34 different species of microorganisms has been studied. It was found that 6 species of microorganisms are lysed in the presence of interleukin-2. All interleukin-2-sensitive microorganisms belong either to the Enterobacteriaceae, Bacillaceae, or the Lactobacillaceae family. It was also found that 12 species of microorganisms are lysed in the presence of lysozyme, and 16 species of microorganisms are lysed in the presence of sodium dodecyl sulfate (SDS). The bacteriolytic activity of interleukin-2 and lysozyme was studied at various pH values.

High-yield reactivation of anionic tobacco peroxidase overexpressed in Escherichia coli.

Anionic tobacco peroxidase (TOP) is extremely active in chemiluminescence reaction of luminol oxidation without addition of enhancers and more stable than horseradish peroxidase under antibody conjugation conditions. In addition, recombinant TOP (rTOP) produced in Escherichia coli is known to be a perfect direct electron transfer catalyst on electrodes of various origin. These features make the task of development of a high-yield reactivation protocol for rTOP practically important. Previous attempts to reactivate the enzyme from E. coli inclusion bodies were successful, but the reported reactivation yield was only 14%. In this work, we thoroughly screened the refolding conditions for dilution protocol and compared it with gel-filtration chromatography. The impressive reactivation yield in the dilution protocol (85%) was achieved for 8 µg/mL solubilized rTOP protein and the refolding medium containing 0.3 mM oxidized glutathione, 0.05 mM dithiothreitol, 5 mM CaCl2, 5% glycerol in 50 mM Tris-HCl buffer, pH 9.6, with 1 µM hemin added at the 24th hour of incubation. A practically important discovery was a 30-40% increase in the reactivation yield upon delayed addition of hemin. The reactivation yield achieved is one of the highest reported in the literature on protein refolding by dilution. The final yield of purified active non-glycosylated rTOP was ca. 60 mg per L of E. coli culture, close to the yield reported before for tomato and tobacco plants overexpressing glycosylated TOP (60 mg/kg biomass) and much higher than for the previously reported refolding protocol (2.6 mg per L of E. coli culture).

Site-directed mutagenesis of tobacco anionic peroxidase: Effect of additional aromatic amino acids on stability and activity.

Tobacco anionic peroxidase (TOP) is known to effectively catalyze luminol oxidation without enhancers, in contrast to horseradish peroxidase (HRP). To pursue structure-activity relationship studies for TOP, two amino acids have been chosen for mutation, namely Thr151, close to the heme plane, and Phe140 at the entrance to the active site pocket. Three mutant forms TOP F140Y, T151W and F140Y/T151W have been expressed in Escherichia coli, and reactivated to yield active enzymes. Single-point mutations introducing additional aromatic amino acid residues at the surface of TOP exhibit a significant effect on the enzyme catalytic activity and stability as judged by the results of steady-state and transient kinetics studies. TOP T151W is up to 4-fold more active towards a number of aromatic substrates including luminol, whereas TOP F140Y is 2-fold more stable against thermal inactivation and 8-fold more stable in the reaction course. These steady-state observations have been rationalized with the help of transient kinetic studies on the enzyme reaction with hydrogen peroxide in a single turnover regime. The stopped-flow data reveal (a) an increased stability of F140Y Compound I towards hydrogen peroxide, and thus, a higher operational stability as compared to the wild-type enzyme, and (b) a lesser leakage of oxidative equivalents from TOP T151W Compound I resulting in the increased catalytic activity. The results obtained show that TOP unique properties can be further improved for practical applications by site-directed mutagenesis.

Morphology controlled NH4V3O8 microcrystals by hydrothermal synthesis.

Single crystalline ammonium trivanadate NH4V3O8 with variable morphologies, including shuttles, flowers, belts, and plates, was synthesized by the hydrothermal treatment of NH4VO3 with acetic acid. The crystals optimally grow under gentle conditions of 140 °C for 48 h. The resulting NH4V3O8 microcrystals were characterized by means of X-ray diffraction, scanning electron microscopy, infrared and Raman spectroscopy, static magnetization studies, and thermal analysis. The key factors to control the size and morphology of the crystals are the pH value and the vanadium concentration. A tentative microscopic growth mechanism is proposed and it is demonstrated how shape and morphology of the resulting microcrystalline material can be tuned by appropriate synthesis parameters.

Horseradish peroxidase: modulation of properties by chemical modification of protein and heme.

Horseradish peroxidase (HRP) is one of the most studied enzymes of the plant peroxidase superfamily. HRP is also widely used in different bioanalytical applications and diagnostic kits. The methods of genetic engineering and protein design are now widely used to study the catalytic mechanism and to improve properties of the enzyme. Here we review the results of another approach to HRP modification-through the chemical modification of amino acids or prosthetic group of the enzyme. Computer models of HRPs with modified hemes are in good agreement with the experimental data.