Molekulyarnaya Biologiya最新文献

Low molecular-weight thiols as glutathione and cysteine are an important part of the cell's redox regulation system. Previously, we have shown that inactivation of ADP-heptose synthesis in Escherichia coli with a gmhA deletion induces the oxidative stress. It is accompanied by rearrangement of thiol homeostasis and increased sensitivity to antibiotics. In our study, we found that restriction of cysteine metabolism (ΔcysB and ΔcysE) and inhibition of glutathione synthesis (ΔgshAB) lead to a decrease in the sensitivity of the ΔgmhA mutant to antibiotics but not to its expected increase. At the same time, blocking of the export of cysteine (ΔeamA) or increasing import (Ptet-tcyP) into cells of the oxidized form of cysteine-cystine leads to an even greater increase in the sensitivity of gmhA-deleted cells to antibiotics. In addition, there is no correlation between the cytotoxic effect of antibiotics and the level of reactive oxygen species (ROS), the total pool of thiols, or the viability of the initial cell population. However, a correlation between the sensitivity to antibiotics and the level of oxidized glutathione in cells was found in our study. Apparently, a decrease in the content of low-molecular-weight thiols saves NADPH equivalents and limits the processes of protein redox modification. This leads to increasing of resistance of the ΔgmhA strain to antibiotics. An increase in low-molecular-weight thiols levels requires a greater expenditure of cell resources, leads to an increase in oxidized glutathione and induces to greater increase in sensitivity of the ΔgmhA strain to antibiotics.

The transcription factor NRF2 is a major regulator of cell antioxidant defense. NRF2 is activated by various stimuli, such as oxidants and electrophiles, to induce transcription of a number of genes whose products are involved in xenobiotic metabolism and contribute to the reduction of oxidative stress. NRF2 is one of the key transcription factors that ensure the endothelial cell function. The endothelium is a cell layer that lines the lumens of blood vessels and performs various homeostatic functions, controlling migration of leukocytes, regulating thrombosis and vascular tone, and playing a role in angiogenesis. Endothelial dysfunction is often accompanied by inflammation and oxidative stress, which may lead to cell aging and cell death by apoptosis, necrosis, or ferroptosis. Endothelial dysfunction contributes to the development of diabetes and common cardiovascular disorders, such as hypertension and atherosclerosis. Many pathophysiological processes in the endothelium, including senile changes, are associated with decreased NRF2 activity, leading to inflammatory activation and decreasing activity of the cell antioxidant defense systems. Activation of the NRF2 signaling pathway generally contributes to the resolution of inflammation and oxidative stress. The review focuses on the role that NRF2 plays in basic functions of the endothelium in normal and pathological conditions. Advantages and disadvantages of NRF2 activation as a way to prevent and treat cardiovascular diseases are discussed additionally.

This review considers the recent progress on the role of heat shock proteins (HSPs), as well as transcription factors of heat shock proteins genes (HSFs) in protecting plants from oxidative stress induced by various types of abiotic and biotic stresses. HSPs are pleiotropic proteins involved in various intracellular processes and performing many important functions. In particular, HSPs increase plant resistance to stress by protecting the structure and activity of proteins of the antioxidant system. Overexpression of Hsp genes under stressful conditions, leading to an increased content of HSPs, can be used as a marker of oxidative stress. Plant HSFs are encoded by large gene families with variable sequences, expression and function. Plant HSFs regulate transcription of a wide range of stress-induced genes, including HSPs and other chaperones, reactive oxygen species scavengers, enzymes involved in protective metabolic reactions and osmolytic biosynthesis, or other transcriptional factors. Genome-wide analysis of Arabidopsis, rice, poplar, lettuce, and wheat revealed a complex network of interaction between the Hsps and Hsfs gene families that form plant protection against oxidative stress. Plant protection systems are discussed, with special emphasis on the role of HSPs and HSFs in plant responses to stress, which will be useful for the development of technologies to increase productivity and stress resistance of plant crops.

Hsp70 and hydrogen sulfide donors reduce inflammatory processes in human and animal cells. The biological action mediated by Hsp70 and H2S donors (GYY4137 and sodium thiosulfate) depends on their protection kinetics from cell activation by lipopolysaccharides. However, the molecular mechanisms of action of Hsp70 and H2S are not well understood. We studied the effect of human recombinant Hsp70 and H2S donors on the formation of reactive oxygen species and tumor necrosis factor-alpha induced in human cells (THP-1) by lipopolysaccharides. Transcriptomic changes occurring in these cells after LPS administration in combination with GYY4137 pretreatment were investigated. The results we obtained showed that Hsp70 and hydrogen sulfide donors reduce inflammatory processes in cells activated by the action of LPS. Hsp70 and H2S donors differed in the kinetics of the protective action, while hydrogen sulfide donors turned out to be more effective. The role of endocytosis in the mechanisms of protection of cells by H2S and Hsp70 donors from the action of LPS was studied. It has been found that GYY4137 pretreatment of LPS-exposed cells reduces the LPS-induced induction of various pro-inflammatory genes and affects the expression of genes of various intracellular signaling pathways.

Changes in the activity of antioxidant systems in Escherichia coli during phosphate starvation have been studied. It is shown that starvation was accompanied by a decrease in the intensity of respiration, an increase in the rate of superoxide production, and a decrease in the level of ATP. Simultaneously, there was a decrease in H2O2 in the medium and a significant increase in the expression of the katG and katE genes which encode the HPI and HPII catalases, respectively. At the same time, there was no drop in the membrane potential, which may indicate the retention of normal membrane activity in starving cells. It has been shown for the first time that the transition of E. coli to phosphate starvation is accompanied by significant changes in the status of glutathione. The most important of these are associated with a decrease in the level of reduced glutathione in the medium (GSHout) and with a simultaneous increase in its content in the cytoplasm (GSHin), as well as a shift in the GSHin to oxidized glutathione form (GSSGin) ratio towards reductive values, and GSHout/GSSGout towards oxidative values. Among the mutants used in the work, the gor trxB double mutant, which is deficient in the synthesis of glutathione reductase and thioredoxin reductase, showed the most pronounced distinctive features. Compared to the parental strain, this mutant showed a multiple higher expression of katG::lacZ, the highest level of oxidized intra- and extracellular glutathione, and, accordingly, the lowest GSH/GSSG ratio in both compartments. In general, the data we obtained indicate that during phosphate starvation the interaction of the glutathione redox-system and regulons that control protection against reactive oxygen species creates conditions that allow maintaining the concentration of ROS below the toxic level. As a result, phosphate-starved E. coli cells can maintain high viability for a long period of time, which allows them to quickly resume growth after the addition of phosphate.

The pathology of diseases arising from infections by viruses of Flaviviridae is largely determined by the development of systemic inflammation. The cytokines interleukin-1beta and interleukin-18 play a key role in triggering inflammation. Their secretion from cells, in its turn, is induced upon activation of inflammasomes. Activation of NLRP3 (NLR pyrin domain-containing family 3) inflammasomes was detected in cells infected with Flaviviridae. Some nonstructural proteins of these viruses have been shown to be able to activate or to inhibit the NLRP3 inflammasome, in particular, through interaction with its components. In this study, a functional NLRP3 inflammasome was reconstructed in human HEK293T cells and the effect of some nonstructural proteins of individual Flaviviridae viruses on it was studied. This model did not reveal any impact of nonstructural NS1 proteins of the West Nile virus, NS3 of hepatitis C virus, or NS5 of tick-borne encephalitis virus on the inflammasome components content. At the same time, in the presence of the NS1 of the West Nile virus and NS5 of the tick-borne encephalitis virus, the level of secretion of interleukin-1beta did not change, whereas in the presence of the NS3 protein of the hepatitis C virus, it increased by 1.5 times. Thus, NS3 can be considered as one of the factors of NLRP3 inflammasome activation and inflammatory pathogenesis in chronic hepatitis C virus infection.

Digital PCR (dPCR) is a nucleic acid quantification method that is widely used in genetic analysis. One of the most significant advantages of dPCR over other methods is the possibility of absolute quantitative determination of genetic material without construction of calibration curves, which allows one to detect even single molecules of nucleic acids, and, hence, provides early diagnosis of diseases. One specific characteristic of dPCR is the detection of the analyzed biological object in each microreaction, followed by the presentation of the analysis results in a binary system, thereby giving the method its name. The key aspects of developing the dPCR method, i.e., from the first devices based on microfluidic chip technology to modern systems capable of measuring a target at a concentration of up to 1 in 100000 copies are shown in the current work. We analyzed the data on the detection of various pathogens using dPCR, as well as summarizing various study results demonstrating the innovativeness of this method. Both the possibilities of multiplex dPCR analysis and its potential in clinical practice are presented. This review also addresses the issue of the role of dPCR in the development of noninvasive methods for analysis of oncological diseases. Possible ways of developing dPCR technology were emphasized, including its use as a "point-of-care" system.

The ubiquitin-proteasome system (UPS) provides hydrolysis of most intracellular proteins in proteasomes. There are various forms of proteasomes that differ, among other things, in the set of proteolytic subunits and the presence of activators. Alzheimer's disease (AD) is characterized by disturbances in the functional state of the UPS. At the same time, an increase in the expression of certain forms of proteasomes, in particular, proteasomes containing immune subunits (nonconstitutive proteasomes), has been shown. Here, we studied dynamic changes in the expression of catalytic proteasome subunit genes and corresponding proteins in the cerebral cortex of animals using a mouse model of AD (5xFAD transgenic mice). Increases by 4 and 6 folds in transcripts of the PSMB9 and PSMB8 genes encoding immune proteasome subunits were detected, as well as a significant increase in the content of immune β-subunits (by 2.8 folds, β1i; 2.2 folds, β2i) in samples from 5xFAD mice at the age of 380 days, compared with samples from mice at 60 days of age. Moreover, the activation of both 20S and 26S proteasomes containing immune subunits were revealed in samples from 380 days old 5xFAD mice by electrophoresis in native conditions. This indicates activated synthesis of the immune subunits and assembly of nonconstitutive proteasomes at the terminal stage of pathology development. The obtained data, in combination with the available literature, indicate that the activation of nonconstitutive proteasomes is a universal phenomenon characteristic of various animal models of AD, which may reflect both the development of neuroinflammation and adaptive processes in tissues induced by the accumulation of toxic protein aggegates.

Multiple sclerosis (MS) is a chronic autoimmune inflammatory and neurodegenerative disease of the central nervous system, which is characterized by significant clinical heterogeneity. Primary progressive MS (PPMS) develops in 10-15% of patients. Unlike the most common relapsing-remitting form of MS, PPMS involves steady progress of neurodegeneration and, as a consequence, a persistent gradual increase in neurological symptoms. The peculiarities of epigenetic regulation of gene expression may be one of the reasons for the differences in the pathogenesis of the two MS forms. DNA methylation is one of the key epigenetic mechanisms, which remains almost unexplored in different cell populations of PPMS patients. The goal of this work was to identify differential methylation profiles of the CpG sites in the CD14+ monocyte DNA, which characterize PPMS. A genome-wide analysis of DNA methylation in PPMS patients and healthy individuals has identified 169 differentially methylated positions (DMPs), 90.5% of which were hypermethylated in PPMS patients. More than half of all DMPs are located in/near known genes and within CpG islands and their neighboring regions, which indicates their high functional significance. We have found six differentially methylated regions (DMRs) in the OR2L13, CAT, LCLAT1, HOXA5, RNF39, and CRTAC1 genes involved in inflammation and neurodegeneration, which indicates active epigenetic regulation of their expression.

Proteasomes are key components of the ubiquitin-proteasome system. Various forms of proteasomes are known. During aging, disturbances in the functioning of proteasomes have been revealed, as well as increased expression of their particular forms. Considering these data, we studied the expression of genes encoding the constitutive and immune subunits of proteasomes in cerebral cortex samples from C57BL/6 mice at the ages of 60, 190, 380, and 720 days. In addition, the contents of constitutive and immune proteasome subunits, chymotrypsin-like and caspase-like activities of proteasome pools, as well as the activity of the β5i immune subunit were studied in tissue homogenates. The chymotrypsin-like activity and the activity of the β5i subunit of different forms of proteasomes separated by electrophoresis in native gel were characterized. Compared with samples from young animals, in the cerebral cortex of animals at an age of 720 days the following changes in the expression patterns of proteasome genes were revealed: a decreased expression of the PSMB5 gene encoding constitutive proteasome subunit β5; increased expression of genes encoding immune proteasome subunits β5i and β1i. In tissue homogenates of aged mice, an increase in the content of immune subunits β1i and β2i was shown. In samples from old animals, chymotrypsin-like activity was decreased and a tendency to a decrease in caspase-like activity of proteasomes as well as the β5i subunit activity was revealed. Analysis of the activity of native complexes in tissues obtained from old animals revealed decreased chymotrypsin-like activity of 26S and 20S proteasomes containing the β5i subunit. Based on the obtained data, it can be assumed that changes in the pool of nonconstitutive proteasomes reflect aging-associated adaptive processes in the mouse brain.