Ischemia–reperfusion injury (IRI) is a common phenomenon that develops both from natural causes and during major operations. Many intracellular processes mediated by calcium ions are involved in the development of IRI. Currently, chemical calcium channel blockers are used but they have a number of limitations. In this article, we study the effect of the omega-hexatoxin-Hv1a peptide toxin, an alternative to chemical calcium channel blockers, on the mechanisms of IRI development in epithelial cell culture. The toxin was produced using solid phase peptide synthesis. IRI was caused by deprivation of glucose, serum and oxygen. The data obtained demonstrate that the omega-hexatoxin-Hv1a toxin in nanomolar concentrations is able to prevent the development of apoptosis and necrosis in epithelial cells by reducing the concentration of calcium, sodium and potassium ions, as well as by delaying rapid normalization of the pH level, affecting the mitochondrial potential and oxidative stress. This toxin can be used as an alternative to chemical calcium channel blockers for preventing tissue and organ IRI due to its low-dose requirement and high bioavailability.

The H/ACA snoRNA family is involved in pseudouridine biogenesis. It prevents genetic changes in cells and makes them more stable due to ribosomal RNA characteristics. Therefore, the study of H/ACA snoRNA expression in cell lines with chromosomal disorders after irradiation is of particular interest. The purpose of the study is to analyze the effect of chromosomal disorders on H/ACA snoRNA expression in radioresistant K562 and radiosensitive HL-60 cell lines after radiation exposure. Materials and Methods. K562 and HL-60 cell lines were exposed to radiation (4 Gy). H/ACA snoRNA expression was analyzed by NGS sequencing (1, 4, and 24 hours after irradiation). Results. The authors revealed differences in H/ACA snoRNA expression by chromosomes in the studied cell lines, as well as the impact of chromosomal abnormalities on H/ACA snoRNA expression after radiation exposure. Changes in the copy number of normal chromosomes lead to minor changes in H/ACA snoRNA expression. Marker chromosomes disrupt H/ACA snoRNA expression. Thus, is becomes impossible to use H/ACA snoRNAs located in abnormal chromosomes as radioresistance markers. Moreover, marker chromosomes decrease the number of H/ACA snoRNAs expressed in K562, despite the greater amount of genetic material.

Myocardial infarction is one of the most common cardiovascular diseases worldwide. Interruption of coronary blood flow subjects cardiomyocytes to stress, while reperfusion reintroduces substrate and oxygen, providing a sharp normalization of the intracellular milieu. All this paradoxically increases cell death, resulting in ischemia-reperfusion injury. It has long been known that sodium overload in the myocardium is one of the most important mechanisms underlying the ischemia-reperfusion injury. In our work, we used mu-agatoxin-Aa1a to reduce the influx of Na+ at the reperfusion stage and, thereby, to reduce damage. Objective. The aim of the study is to examine the effect of mu-agatoxin-Aa1a on cardiomyocyte cell death in an in vitro ischemia-reperfusion injury model. Materials and Methods. The study was performed on H9C2 cardiomyocyte culture. Fluorescence microscopy was used to assess the apoptosis and necrosis levels, and sodium ion concentration. Spectrophotometric method for determining lactate dehydrogenase concentration was used to confirm the necrosis level. The ischemia-reperfusion injury model was based on 18-hour culture incubation in the medium with partial glucose, serum, and oxygen deprivation, followed by transfer to a nutrient medium for 2 hours. The toxin was added at the beginning of the reperfusion stage Results: In case of increased cell death caused by apoptosis and necrosis in the ischemia-reperfusion injury model, the addition of toxin at a concentration of 50 nM causes an increase in cell survival due to a decrease in the sodium ion concentration. Conclusion. The peptide toxin mu-agatoxin-Aa1a, which targets sodium voltage-gated channels and can change their conductance, at a concentration of 50 nM significantly reduces cardiomyocyte death in an in vitro model of ischemia-reperfusion injury.

The study objective. This paper reviews the express of C/D box snoRNAs (small nucleolar RNAs) and possibility of their use as biomarkers of radioresistance in chromosomal abnormalities. Material and Methods. The study compared the values of log2FC express of snoRNA C/Dbox in radiosensitive (HL-60) and radioresistant (K562) cell lines with different levels of chromosomal abnormalities. The cells were irradiated with X-ray radiation once at a dose of 4 Gy. The expression of snoRNA C/D was evaluated 1, 4 and 24 hours after irradiation, using new generation sequencing (NGS) MiSeq. Results. Different log2FC values were obtained in HL-60 and K562 cell lines 1 hour, 4 and 24 hours after irradiation. Positive expression of C/D snoRNA prevails in HL-60 throughout the experiment. In K562, the predominance of positive values of C/D snoRNA expression was observed 4 hours after irradiation, and negative values of log2FC were observed 24 hours later. the more anomalies there were in the chromosome, the greater the difference in expression we observed. at the same time, the number of C/D snoRNA changed maximally 24 hours after irradiation in the studied cell lines. We noted a greater number of C/D snoRNAs in the HL-60 cell line, and only 3 expressed C/D snoRNAs in the 15th marker chromosome in K562 out of 16 in HL-60 in the same chromosome. Conclusion. Our study showed a low informative value of using C/D snoRNAs family as markers of radiosensitivity in the presence of chromosomal abnormalities in cancer cells.

Arthropod peptide toxins rich in disulfide bonds are one of the potential sources of bioactive substances. Due to their structure, toxins have increased stability and are able to bind to ion channels, blocking them or changing the gating mechanism. Some spider toxins bind to different types of calcium channels. Calcium ions, in turn, play an important role in many cellular processes, namely, apoptosis. The aim of this paper is to investigate the effect of a number of toxins – arachnid ion-channel blockers in – on intracellular processes associated with the induction of apoptosis in mammalian cells. Materials and Methods. Toxins ω-hexatoxin-Hv1a, ω-theraphotoxin-Hhn2a were used in the study, as they are inhibitors of L- and P/Q-type calcium channels, respectively. Apoptosis was induced using the AC-1001H3 peptide. The authors used fluorescence microscopy to study the effect of toxins on the apoptosis level, oxidative stress, and mitochondrial potential in CHO-K1 cells. Results. The authors observed that incubation of cells with toxins (10 nM) and AC-1001H3 peptide led to increased ROI intracellular concentration, which should have induced apoptotic mechanisms. However, the effect was the opposite. In addition, there was an increase in the mitochondrial potential level. Despite this, the used toxins blocked apoptosis caused by AC-1001H3 and reduced the natural apoptosis level in the CHO-K1 cells. Conclusion. The study demonstrated the antiapoptotic effect of some arthropod peptide toxins. The studied toxins can be used in the treatment of pathologies associated with the activation of apoptotic mechanisms. Keywords: apoptosis, spider toxin, peptide. Пептидные токсины членистоногих, богатые дисульфидными связями, являются одним из потенциальных источников биоактивных веществ. За счет своей структуры токсины обладают повышенной стабильностью и способны связываться с ионными каналами, блокируя их или изменяя механизм стробирования. Ряд токсинов пауков способен связываться с кальциевыми каналами разных типов. Ионы кальция в свою очередь играют важную роль во многих процессах в клетке, одним из которых является апоптоз. Цель работы – исследовать влияние ряда токсинов – блокаторов ионных каналов паукообразных – на внутриклеточные процессы, связанные с индукцией апоптоза в клетках млекопитающих. Материалы и методы. В исследовании использовались токсины ω-hexatoxin-Hv1a, ω-theraphotoxin-Hhn2a, которые являются ингибиторами кальциевых каналов L- и P/Q-типов соответственно. Индукция апоптоза проводилась с использованием пептида AC-1001H3. Изучалось влияние токсинов на уровень апоптоза, оксидативного стресса и митохондриального потенциала в клетках линии CHO-K1 с использованием методов флуоресцентной микроскопии. Результаты. Было установлено, что инкубация клеток с токсинами в концентрации 10 нМ и индуктором апоптоза AC-1001H3 приводила к росту внутриклеточной концентрации активных форм кислорода, что должно индуцировать апоптотические механизмы, однако эффект был противоположным. Кроме того, происходило повышение уровня митохондриального потенциала. Несмотря на это использованные токсины блокировали апоптоз, вызванный AC-1001Н3, и снижали уровень естественного апоптоза в культуре клеток CHO-K1. Выводы. Проведенное исследование продемонстрировало антиапоптотический эффект ряда пептидных токсинов членистоногих. Изученные токсины могут найти применение при лечении патологии, связанной с активацией апоптотических механизмов. Ключевые слова: апоптоз, токсин паука, пептид.

Prostate cancer is one of the most commonly diagnosed cancers worldwide. Targeted therapy is an anticancer strategy using short peptides targeting prostate-specific membrane antigen (PSMA). However, short peptides have a number of disadvantages, including low stability in vivo. This problem can be solved by using toxins with an inhibitory cystine knot with a short built in peptide. The aim of the study is to examine the stability and ability of the PSMA/C1-C2 peptide, created on the base of knottin U5-scytotoxin-Sth1a and a short peptide tropic to PSMA, to bind to receptors on the surface of prostate cancer cells and to compare the results with a market image drug PSMA I&T and a specific PSMA inhibitor. Materials and Methods. A solid-phase peptide synthesizer was used for peptide synthesis, chromatography and mass spectrometry were applied for analysis and purification. A competitive inhibition analysis was performed with radiolabeled commercial PSMA I&T in excess of PSMA/C1-C2 and FAM-labeled PSMA/C1-C2 with a specific PSMA inhibitor 2-PMPA. PSMA-positive culture 22Rv1 and PSMA-negative culture PC-3 were used as cell cultures. Chromatography was used to access peptide stability. Results. As a result, it was observed that the synthesized PSMA/C1-C2 structure, created on the basis of knottin and a short peptide, prevents binding of PSMA I&T to receptors on the surface of 22Rv1 cells. The decrease in PSMA/C1-C2 binding in the presence of 2-PMPA suggests that PSMA/C1-C2 is targeted for prostate-specific membrane antigen. In addition, PSMA/C1-C2 peptide has increased stability compared to PSMA I&T.