Molekulârnaâ biologiâ

NO is a gaseous signaling redox-active molecule that functions in various eukaryotes. However, its synthesis, turnover, and effects in cells are specific in plants in several aspects. Compared with higher plants, the role of NO in Chlorophyta has not been investigated enough. Yet, some of the mechanisms for controlling levels of this signaling molecule have been characterized in model green algae. In Chlamydomonas reinhardtii, NO synthesis is carried out by a dual system comprising nitrate reductase and NO-forming nitrite reductase. Other mechanisms that might produce NO from nitrite are associated with components of mitochondrial electron-transport chain. In addition, NO formation in some green algae proceeds by oxidative mechanism similar to that in mammals. Recent discovery of L-arginine-dependent NO synthesis in colorless alga Polytomella parva suggests the existence of a protein complex with enzyme activity that are similar to animal nitric oxide synthase. This latter finding paves the way for further research into potential members of the NO synthases family in Chlorophyta. Beyond synthesis, the regulatory processes to maintain intracellular NO levels are also an integral part for its function in cells. Members of the truncated hemoglobins family with dioxygenase activity can convert NO to nitrate, as was shown for C. reinhardtii. In addition, the implication of NO reductases in NO scavenging has also been described. Even more intriguing, unlike in animals, the typical NO/cGMP signaling module appears not to be used by green algae. S-nitrosylated glutathione, which is considered the main reservoir for NO, provides NO signals to proteins. In Chlorophyta, protein S-nitrosation is one of the key mechanisms of action of the redox molecule. In this review, we discuss the current state-of-the-art and possible future directions related to the biology of NO in green algae.

Cancer cells are characterized by an increased level of metabolism and are highly dependent on the correct functioning of the processes that ensure homeostasis. Reactive sulfur species (RSS) are important molecular modulators of metabolic processes in both healthy and tumor cells. The effect of RSS and, in particular, H₂S, on key cellular systems, including the ubiquitin-proteasome system (UPS), which ensures the destruction of most intracellular proteins, has been shown. The main components of the UPS are proteasomes ‒ multisubunit protein complexes, within which protein proteolysis occurs. At the same time, data on the effect of H₂S directly on the pool of proteasomes in tumor cells are insufficient. Here, we studied the effect of incubation of SW620B8-mCherry colon adenocarcinoma cells expressing a fluorescently labeled proteasome subunit with 50, 100, and 200 µM of hydrogen sulfide donor GYY4137. The effect of the substance on the proteasome pool was assessed 6, 24, 48, and 72 h after administration. It was shown that the chymotrypsin-like and caspase-like proteasome activity decreases in cells incubated with 200 µM of the GYY4137 for 24 h. This coincided with an increase in the expression of proteasome subunit genes. In lysates of cells incubated with 200 µM GYY4137 for 48 h an increase in the content of the constitutive β5 subunit was observed. Against this background, the activity of proteasomes in cells levels off. Following prolonged incubation with GYY4137 (72h), an increase in the expression levels of some proteasome genes was also observed, though this did not have a significant effect on the activity and subunit composition of proteasomes. Thus, the data obtained indicate the modulation of proteasome activity by the hydrogen sulfide donor, as well as the effect of GYY4137 on the levels of transcription and translation of proteasome genes.

The review considers the recent progress on the role of heat shock proteins (HSPs), as well as transcription factors of heat shock proteins (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 Hsps genes under stressful conditions, leading to an increased content of HSP, 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 Arabidodpsis, rice, poplar, lettuce and wheat revealed a complex network of interaction between 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 response to stress, which will be useful for the development of technologies to increase productivity and stress resistance of plant crops.

Plant polyphenols are characterized by a wide range of biological activities, including antioxidant properties, and have a high geroprotective potential. The purpose of this work was to investigate the effect of the extract of rowan berries (Sorbus aucuparia L.) on the lifespan and stress resistance of Drosophila melanogaster with the identification of possible mechanisms of its biological activity. It has been established that the ethanol extract of S. aucuparia berries, the main components of which are rutin and cyanidin-3-rutinoside, has a pronounced antioxidant activity in vitro. At the same time, treatment with rowan berry extract increased the r-esistance of D. melanogaster males to starvation, but reduced resistance to hyperthermia. In females, the e-xtract reduced resistance to oxidative stress but increased resistance to hyperthermia. The effects of rowan berry extract on longevity depended both on its concentration and on the sex of fruit flies. In response to treatment with rowan berry extract, D. melanogaster males and females showed slight differences in the background level of expression of cellular stress response genes, including heat shock genes (hsp27, hsp68, hsp83), oxidative stress resistance genes (hif1, nrf2, sod1), circadian rhythm genes (clk, per), and the longevity gene sirt1, which may explain the differences in the observed effects.

The aim of this work was to study effects of thymosin-1 alpha (Tα1) on the anti-inflammatory response of RAW 264.7 macrophages cultured in the presence of lipopolysaccharide (LPS) from the walls of gram-negative bacteria. Also we evaluated production of pro-inflammatory cytokines and activity of the NF-κB and SAPK/JNK signaling pathways. In addition, the level of expression of a number of genes that regulate cell apoptosis, as well as the activity of receptors involved in the pro-inflammatory response, was determined. Firstly, the addition of Tα1 normalized the level of cytokine production to varying degrees, with a particularly noticeable effect on IL-1β and IL-6. Secondly, the addition of Tα1 normalized activity of the NF-κB and SAPK/JNK signaling cascades and the expression of the Tlr4 gene. Thirdly, Tα1 significantly reduced p53 and the activity of the P53 gene, which is a marker of cell apoptosis. Fourthly, it was shown that an increase in Ar-1 gene expression under the influence of LPS was significantly reduced using Tα1. Thus, it was found that the presence of Tα1 in the RAW 264.7 cell culture medium significantly reduced the level of the pro-inflammatory response of cells.

Inflammatory bowel diseases are widely spread in industrial countries with every 20^th citizen being affected. Dysregulation of epithelial barrier function is considered to play a key role in the development of inflammatory bowel diseases. Intestinal epithelium permeability depends mostly on the condition of intercellular contacts and epithelial cells' renewal ability. Mitochondria participate in the regulation of various intracellular processes besides performing the energetic function. Recent data indicate the potential role of mitochondria in intestinal epithelial barrier regulation and inflammatory bowel diseases onset. Mitochondrial dysfunction may be one of the reasons for disruption of the structure of tight junctions and the cytoskeleton of intestinal epithelial cells, as well as a decrease in the ability of the epithelial lining to self-renewal. All this leads to a decrease in the barrier function of the intestinal epithelium and the development of inflammatory bowel diseases. Nevertheless, the mechanisms of these processes are still unclear and further research is required.

Vitamin B12, or cobalamin, is essential for normal body function and used in the therapy of different diseases. A several studies have shown that vitamin B12 has anti-inflammatory and antioxidant properties that can play an important role in the prevention of some diseases. On the other hand, it has been reported that vitamin B12 in combination with such reducing agents as ascorbate (vitamin C) and thiols showed prooxidant activity. This review provides information on the roles of vitamin B12 in diseases accompanied by inflammation and oxidative stress and the effects of vitamin B12 administrated alone and in combinations with different reducing agents such as ascorbate and thiols on oxidative stress. In addition, the mechanisms of prooxidant actions of combinations of vitamin B12 with these reducing agents depending on the form of vitamin B12 (hydroxocobalamin and cyanocobalamin) are discussed. Understanding the mechanisms of prooxidant action of vitamin B12 is necessary for developing strategies for therapeutic administration of vitamin B12.

Melittin, a peptide from bee venom, was found to interact with many proteins, including calmodulin target proteins and ion-transporting P-type ATPases. It is assumed that melittin mimics a protein module involved in protein-protein interactions within cells. Previously, a Na⁺/K⁺-ATPase containing the α1 isoform of the catalytic subunit was found to co-precipitate with a protein with a molecular weight of about 70 kDa that interacts with antibodies against melittin by cross immunoprecipitation. In the presence of a specific Na⁺/K⁺-ATPase inhibitor (ouabain), the amount of protein with a molecular weight of 70 kDa was increased in the precipitate. In order to identify melittin-like protein from murine kidney homogenate, a fraction of proteins (with a molecular mass of approximately 70 kDa) was obtained using affinity chromatography with immobilized antibodies specific to melittin. By mass spectrometry analysis, the obtained protein fraction was found to contain three molecular chaperones of Hsp70 superfamily: mtHsp70 (mortalin), Hsp73 and Grp78. These data suggest that chaperones from the Hsp70 superfamily contain a melittin-like module.

Delta-aminolevulinic acid dehydratase (ALAD) is a key enzyme in the cytoplasmic pathway of heme biosynthesis. Here, a primary structure of the ALAD gene of the marine cold-water sponge Halisarca dujardinii, a multimeric structure of the ALAD/hemB protein, and the ALAD gene expression during the sponge annual reproductive cycle were analyzed. On the base of results obtained one can suppose that the sponge ALAD gene expression is regulated by the transcription factor GATA-1 and DNA methylation. Re-aggregation of the sponge cells was accompanied by a decrease in ALAD expression and a change in the cellular content of the active ALAD/hemB form. Further study of heme biosynthesis and the role of ALAD/hemB in morphogenesis of basal animals may provide new opportunities for correcting pathologies in higher animals.

Currently, much attention in oncology is devoted to the issues of tumor heterogeneity, which creates serious problems in the diagnosis and therapy of malignant neoplasms. Intertumoral and intratumoral differences relate to various characteristics and aspects of the vital activity of tumor cells, including cellular metabolism. This review provides general information about the tumor metabolic heterogeneity with a focus on energy metabolism, its causes, mechanisms and research methods. Among the methods, fluorescence lifetime imaging is described in more detail as a new promising method for observing metabolic heterogeneity at the cellular level. The review demonstrates the importance of studying the features of tumor metabolism and identifying intra- and intertumoral metabolic differences.

One of the key regulators of hematopoietic stem cell (HSC) maintenance is cellular metabolism. Resting HSCs use anaerobic glycolysis as the main source of energy. During expansion and differentiation under conditions of steady state hematopoiesis, the energy needs of activated HSC increase many fold. To meet the increased demands, cells switch to mitochondrial oxidative phosphorylation, which is accompanied by the increase in reactive oxygen species (ROS) production. Here, the molecular mechanisms maintaining glycolysis in HSCs as well as the factors determining the increase in metabolic activity and the transition to mitochondrial biogenesis during HSC activation are considered. We focus on the role of HIF (hypoxia-inducible factor) proteins as key mediators of the cellular response to hypoxia, and also consider the phenomenon of extraphysiological oxygen shock (EPHOSS), leading to the forced differentiation of HSCs as well as methods of overcoming it. Finally, the role of fatty acid oxidation (FAO) in hematopoiesis is discussed. Understanding the metabolic needs of normal HSCs and precursors is crucial for the development of new treatments for diseases related to the hematopoietic and immune systems.