Igor Kireev

• Ph.D
• Head of Department at Lomonosov Moscow State University

The difficulty in localizing specific cellular proteins by immuno-electron microscopy techniques limits applications of electron microscopy to cell biology. We found that in vivo immunogold labeling improves epitope accessibility, ultrastructural preservation and three-dimensional visualization, and allows correlated light and electron microscopy....

Current models of mitotic chromosome structure are based largely on the examination of maximally condensed metaphase chromosomes. Here, we test these models by correlating the distribution of two scaffold components with the appearance of prophase chromosome folding intermediates. We confirm an axial distribution of topoisomerase IIalpha and the co...

The nuclear lamina represents a multifunctional platform involved in such diverse yet interconnected processes as spatial organization of the genome, maintenance of mechanical stability of the nucleus, regulation of transcription and replication. Most of lamina activities are exerted through tethering of lamina-associated chromatin domains (LADs) t...

In higher eukaryotic interphase nuclei, the 100- to >1,000-fold linear compaction of chromatin is difficult to reconcile with its function as a template for transcription, replication, and repair. It is challenging to imagine how DNA and RNA polymerases with their associated molecular machinery would move along the DNA template without transient de...

A detailed understanding of the principles of the structural organization of genetic material is of great importance for elucidating the mechanisms of differential regulation of genes in development. Modern ideas about the spatial organization of the genome are based on a microscopic analysis of chromatin structure and molecular data on DNA–DNA con...

Electron microscopy (EM) is one of the most efficient methods for studying the fine structure of cells with a resolution thousands of times higher than that of visible light microscopy. The most advanced implementation of electron microscopy in biology is EM tomography of samples stabilized by freezing without water crystallization (cryoET). By cir...

We investigated the role of the nucleolar protein Treacle in organizing and regulating the nucleolus in human cells. Our results support Treacle’s ability to form liquid-like phase condensates through electrostatic interactions among molecules. The formation of these biomolecular condensates is crucial for segregating nucleolar fibrillar centers fr...

Spatiotemporal heterogeneities in the polarity of intracellular LDs play essential roles in cellular function but remain largely unexplored. Here, we introduce excitation spectral phasor microscopy (ExSPM), which combines high-throughput excitation spectral imaging with phasor analysis to detect subtle spectral shifts of fluorophores in response to...

We investigated the role of the nucleolar protein Treacle in organizing and regulating the nucleolus in human cells. Our results support Treacle’s ability to form liquid-like phase condensates through electrostatic interactions among molecules. The formation of these biomolecular condensates is crucial for segregating nucleolar fibrillar centers fr...

The surface structures of archaeal cells, many of which exist at high temperatures, high salinity and non-physiological pH, are key factors for their adaptation to extreme living conditions. In the haloarchaeon Haloarcula hispanica, we have discovered a thin filamentous surface appendage called tat-fimbriae ("tafi"), which were identified to be com...

Integration of the DNA copy of the HIV-1 genome into the cellular genome results in series of damages, the repair of which is critical for successful viral replication. We have previously demonstrated that the ATM and DNA-PK kinases, normally responsible for repairing double-strand breaks in the cellular DNA, are required to initiate HIV-1 post-int...

Platelets are the second most abundant human blood cells. They have an important function to form blood clots at sites of vascular injury to prevent bleeding. Abnormalities of platelet structure can lead to various dysfunctions and life-threatening situations. In some hereditary platelet disorders, morphological examination of platelets with transm...

We investigated the role of the nucleolar protein Treacle in organizing and regulating the nucleolus in human cells. Our results support Treacle’s capacity to form liquid-phase condensates through electrostatic interactions among molecules. The formation of these biomolecular condensates is crucial for segregating nucleolar fibrillar centers from t...

We investigated the role of the nucleolar protein Treacle in organizing and regulating the nucleolus in human cells. Our results support Treacle’s capacity to form liquid-phase condensates through electrostatic interactions among molecules. The formation of these biomolecular condensates is crucial for segregating nucleolar fibrillar centers from t...

Integration of the DNA copy of HIV-1 genome into the cellular genome results in series of damages, repair of which is critical for successful replication of the virus. We have previously demonstrated that the ATM and DNA-PK kinases, normally responsible for repairing double-strand breaks in the cellular DNA, are required to initiate the HIV-1 DNA p...

Duchenne muscular dystrophy is caused by loss of the dystrophin protein. This pathology is accompanied by mitochondrial dysfunction contributing to muscle fiber instability. It is known that mitochondria-targeted in vivo therapy mitigates pathology and improves the quality of life of model animals. In the present work, we applied mitochondrial tran...

The formation of specific cellular protrusions, plasma membrane blebs, underlies the amoeboid mode of cell motility, which is characteristic for free-living amoebae and leukocytes, and can also be adopted by stem and tumor cells to bypass unfavorable migration conditions and thus facilitate their long-distance migration. Not all cells are equally p...

The recent advances achieved in microscopy technology have led to a significant breakthrough in biological research. Super-resolution fluorescent microscopy now allows us to visualize subcellular structures down to the pin-pointing of the single molecules in them, while modern electron microscopy has opened new possibilities in the study of protein...

Cysteine cathepsins play an important role in tumor development and metastasis. The expression of these enzymes is often increased in many types of tumor cells. Cysteine cathepsins contribute to carcinogenesis through a number of mechanisms, including proteolysis of extracellular matrix and signaling molecules on the cell surface, as well as degrad...

The work shows the effect of the metabolic modulator uridine on the functioning and ultrastructure of heart mitochondria in dystrophin-deficient mdx mice. Intraperitoneal administration of uridine (30 mg/kg/day for 28 days) improved K + transport and increased its content in the heart mitochondria of mdx mice to the level of wild-type animals. This...

Liquid-liquid phase separation (LLPS) and liquid-solid phase transition (LSPT) of amyloidogenic proteins are now being intensively studied as a potentially widespread mechanism of pathological amyloids formation. However, the possibility and importance of such a mechanism in living systems is still questionable. Here, we investigated the possibilit...

Cysteine cathepsins play an important role in tumor development and metastasis. The expression of these enzymes is often increased in many types of tumor cells. Cysteine cathepsins contribute to carcinogenesis through a number of mechanisms, including proteolysis of extracellular matrix and signaling molecules on the cell surface, as well as degrad...

It is known that major nuclear processes occur differently in the nucleolus when compared to the remainder of the nucleus. This variation could be associated with the nature of the nucleolus, which is considered a multicomponent liquid environment. Among the numerous nucleolar proteins, Treacle holds a special place due to a wealth of experimental...

Dystrophin-deficient muscular dystrophy (Duchenne dystrophy) is characterized by impaired ion homeostasis, in which mitochondria play an important role. In the present work, using a model of dystrophin-deficient mdx mice, we revealed decrease in the efficiency of potassium ion transport and total content of this ion in the heart mitochondria. We ev...

In present study, we describe “ ta t- fi mbriae (tafi)” – a novel type of archaeal surface appendages isolated from haloarchaeon Haloarcula hispanica . These fi lamental structures are unique because they are formed of protein subunits secreted through the t win- a rginine translocation pathway (Tat-pathway), in contrast to well-known archaeal surf...

Magnetite–gold dumbbell nanoparticles are essential for biomedical applications due to the presence of two surfaces with different chemical natures and the potential combination of magnetic and plasmonic properties. Here, the remote actuation of Fe3O4-Au hybrid particles in a rotating (1 Hz, 7 mT), static (7 mT) or pulsed low-frequency (31 Hz, 175...

Actin cytoskeleton is an essential component of living cells and plays a decisive role in many cellular processes. In mammals, β- and γ-actin are cytoplasmic actin isoforms in non-muscle cells. Despite minor differences in the amino acid sequence, β- and γ-actin localize in different cell structures and perform different functions. While cytoplasmi...

This article discusses the role of electron microscopy in the diagnosis and study of morphological changes that cause platelet structural abnormalities in a variety of congenital diseases. Morphological abnormalities can be divided into the abnormalities of the platelet cytoskeleton, of alpha and dense granules, and membrane abnormalities. Our pape...

Cellular lipid uptake (through endocytosis) is a basic physiological process. Dysregulation of this process underlies the pathogenesis of diseases such as atherosclerosis, obesity, diabetes, and cancer. However, to date, only some mechanisms of lipid endocytosis have been discovered. Here, we show a previously unknown mechanism of lipid cargo uptak...

Principles of DNA folding in the cell nucleus and its dynamic transformations that occur during the fulfillment of basic genetic functions (transcription, replication, segregation, etc.) remain poorly understood, partially due to the lack of experimental approaches to high-resolution visualization of specific chromatin loci in structurally preserve...

DNA-dependent protein kinase (DNA-PK) is a key player in the NHEJ repair pathway. DNA-PK and its subunits, Ku70, Ku80, and catalytic subunit (DNA-PKcs), also participate in other cellular processes; however, there are still no systemic data on the effect of depletion of Ku70, Ku80 and DNA-PKcs on cell functions in the same cell line. Here, we analy...

Предисловие редактора. Несмотря на то, что первые микроскопы были изобретены ещё в 17 веке, планомерное изучение клеток и входящих в их состав органелл получило бурное развитие только во второй половине 19 века. Тогда же появилась наука "Цитология", которая является предшественницей современной науки "Клеточная биология". В отличие от классической...

One of the main factors associated with worse prognosis in oncology is metastasis, which is based on the ability of tumor cells to migrate from the primary source and to form secondary tumors. The search for new strategies to control migration of metastatic cells is one of the urgent issues in biomedicine. One of the strategies to stop spread of ca...

Conventional approaches for studying and molecular typing of tumors include PCR, blotting, omics, immunocytochemistry, and immunohistochemistry. The last two methods are the most used, as they enable detecting both tumor protein markers and their localizations within the cells. In this study, we have investigated a possibility of using RNA aptamers...

Replication stress is one of the main sources of genome instability. Although the replication stress response in eukaryotic cells has been extensively studied, almost nothing is known about the replication stress response in nucleoli. Here, we demonstrate that initial replication stress–response factors, such as RPA, TOPBP1, and ATR, are recruited...

Liquid-liquid phase separation (LLPS) contributes to the spatial and functional segregation of molecular processes. However, the role played by LLPS in chromatin folding in living cells remains unclear. Here, using stochastic optical reconstruction microscopy (STORM) and Hi-C techniques, we studied the effects of 1,6-hexanediol (1,6-HD)-mediated LL...

We have shown previously that two cytoplasmic actin isoforms play different roles in neoplastic cell transformation. Namely, β-cytoplasmic actin acts as a tumor suppressor, whereas γ-cytoplasmic actin enhances malignant features of tumor cells. The distinct participation of each cytoplasmic actin in the cell cycle driving was also observed. The goa...

Mechanical properties of living cells determined by cytoskeletal elements play a crucial role in a wide range of biological functions. However, low-stress mapping of mechanical properties with nanoscale resolution but with a minimal effect on the fragile structure of cells remains difficult. Scanning Ion-Conductance Microscopy (SICM) for quantitati...

Simple Summary The formation of multinucleated cells is critical for mature osteoclast generation. For this to happen, mononuclear pre-osteoclasts migrate in proximity to other pre-osteoclasts to fuse together. This finely regulated process is dependent on the “feeling” and “recognition” between neighboring cells. In this study, we focused on pre-o...

Mitochondria are considered to be the main source of reactive oxygen species (ROS) in the cell. It was shown that in cardiac myocytes exposed to excessive oxidative stress, ROS-induced ROS release is triggered. However, cardiac myocytes have a network of densely packed organelles that do not move, which is not typical for the majority of eukaryotic...

Inhibition of KIT-signaling is a major molecular target for gastrointestinal stromal tumor (GIST) therapy, and imatinib mesylate (IM) is known as the most effective first-line treatment option for patients with advanced, unresectable, and/or metastatic GISTs. We show here for the first time that the inhibition of KIT-signaling in GISTs induces prof...

Hyperthermia has been used as an adjuvant treatment for radio- and chemotherapy for decades. In addition to its effects on perfusion and oxygenation of cancer tissues, hyperthermia can enhance the efficacy of DNA-damaging treatments such as radiotherapy and chemotherapy. Although it is believed that the adjuvant effects are based on hyperthermia-in...

Halophilic archaea from the genus Halorubrum possess two extraordinarily diverged archaellin genes, flaB1 and flaB2. To clarify roles for each archaellin, we compared two natural Halorubrum lacusprofundi strains: One of them contains both archaellin genes, and the other has the flaB2 gene only. Both strains synthesize functional archaella; however,...

Labyrinthulomycetes are mostly fungus‐like heterotrophic protists that absorb nutrients in an osmotrophic or phagotrophic manner. Members of order Labyrinthulida produce unique membrane‐bound ectoplasmic networks for movement and feeding. Among the various types of labyrinthulids’ food substrates diatoms play an important role due to their ubiquito...

Extracellular vesicles (EVs) are released from cells and are present in most bodily fluids. Small EVs, 30-150nm in diameter, known as exosomes, transport regulatory noncoding RNA, lipids, and proteins, and thus participate in cell-to-cell communications and signalling. Exosomes from bovine ovarian follicular fluid (FF) can stimulate proliferation o...

The mechanical properties of PC-3 tumor cells of human prostate cancer before and after exposure to substances acting on the actin cytoskeleton, microtubules, and cell nucleus were measured by scanning ion-conducting microscopy. Changes in local mechanical properties corresponding to the mechanisms of action of these substances were found

The archaellum is a unique motility structure that has only functional similarity to its bacterial counterpart, the flagellum. Archaellar filaments consist of thousands of copies of the protein protomer archaellin. Most euryarchaeal genomes encode multiple homologous archaellins. The role of these multiple archaellin genes remains unclear. Halophil...

Proteins can aggregate in response to stresses, including hyperosmotic shock. Formation and disassembly of aggregates is a relatively slow process. We describe a novel instant response of the cell to hyperosmosis, during which chaperones and other proteins form numerous foci with properties uncharacteristic of classical aggregates. These foci appea...

Wiskott-Aldrich syndrome (WAS) is associated with thrombocytopenia of unclear origin. We investigated real-time cytosolic calcium dynamics, mitochondrial membrane potential and phoszphatidylserine (PS) exposure in single fibrinogen-bound platelets using confocal microscopy. The WAS platelets had higher resting calcium levels, more frequent spikes,...

Induced and frequently unwanted alterations in the mitochondrial structure and functions are a key component of the pathological cascade in many kidney pathologies, including those associated with acute damage. One of the principal pathogenic elements causing mitochondrial dysfunction in Acute Kidney Injury (AKI) is oxidative stress. After ischemia...

The contribution of nucleoli to the cellular stress response has been discussed for over a decade. Stress-induced inhibition of RNA polymerase I-dependent transcription is hypothesized as a possible effector program in such a response. In this study, we report a new mechanism by which ribosomal DNA transcription can be inhibited in response to cell...

The Hutchinson–Gilford progeria syndrome (HGPS) is a premature aging disease caused by mutations of the LMNA gene leading to increased production of a partially processed form of the nuclear fibrillar protein lamin A – progerin. Progerin acts as a dominant factor that leads to multiple morphological anomalies of cell nuclei and disturbances in hete...

The contribution of nucleoli to the cellular stress response has been discussed for over a decade. Stress-induced inhibition of RNA polymerase I-dependent transcription is hypothesized as a possible effector program in such a response. In this study, we report a new mechanism by which riboso-mal DNA transcription can be inhibited in response to cel...

Hypothesis: Magnetic liposomes are shown to release the entrapped dye once modulated by low frequency AC MF. The mechanism and effectiveness of MF application should depend on lipid composition, magnetic nanoparticles (MNPs) properties, temperature and field parameters. Experiments: The study was performed using liposomes of various lipid compos...

Proteins can aggregate in response to stresses, including hyperosmotic shock. Formation and disassembly of aggregates is a relatively slow process. We describe a novel instant response of the cell to hyperosmosis, during which chaperones and other proteins form numerous foci with properties uncharacteristic of classical aggregates. These foci appea...

A novel approach to the synthesis of pH-sensitive prodrugs has been proposed: thiourea drug modification. Resulting prodrugs can release the cytotoxic agent and the biologically active 2-thiohydantoin in the acidic environment of tumor cells. The concept of acid-catalyzed cyclization of thioureas to 2-thiohydantoins has been proven using a FRET mod...

Background Theranostics application of superparamagnetic nanoparticles based on magnetite and maghemite is impeded by their toxicity. The use of additional protective shells significantly reduced the magnetic properties of the nanoparticles. Therefore, iron carbides and pure iron nanoparticles coated with multiple layers of onion-like carbon sheath...

We have proposed a novel approach to the synthe-sis of pH-sensitive prodrugs: thiourea drug modification. The resulting prodrugs capable of releasing the cytotoxic agent and the biologically active 2-thiohydantoin in the acidic environment of tumor cells. The concept of acid-catalyzed cyclization of thioureas to 2-thiohydantoins has been proven usi...

Abstract Photoconvertible fluorescent proteins (PCFPs) are widely used as markers for the visualization of intracellular processes and for sub-diffraction single-molecule localization microscopy. Although wild type of a new photoconvertible fluorescent protein SAASoti tends to aggregate, we succeeded, via rational mutagenesis, to obtain variants th...

Magnetic nanoparticles are widely used in various fields of biomedicine. They can combine both therapy and diagnostics modalities thus opening many opportunities for their application. In our work, we have evaluated their ability to work as contrast agents for magnetic resonance imagining and drug delivery systems for photosensitizers. We have show...

High-quality, 25 nm octahedral-shaped Fe3O4 magnetite nanocrystals are epitaxially grown on 9 nm Au seed nanoparticles using a modified wet-chemical synthesis. These Fe3O4-Au Janus nanoparticles exhibit bulk-like magnetic properties. Due to their high magnetization and octahedral shape, the hybrids show superior in vitro and in vivo T2 relaxivity f...

The overwhelming majority of investigations on mitochondrial morphology were performed using S. cerevisiae. In this study we showed the benefits of applying new model organisms including petite-negative D. magnusii and Y. lipolytica yeasts for visualization of mitochondrial fragmentation. Normally giant D. magnusii cells and filament-like Y. lipoly...

Current data show that the cytosol exhibits heterogeneous distribution and diffusion of its components, and the basis of this heterogeneity is mostly unknown. However, cytoplasmic architecture should critically impact most cellular processes. We observed a novel phenomenon that highlights this architecture in yeast. During hyperosmotic shock, sever...

In this paper, we investigated the delivery efficiency of doxorubicin by magnetite nanoparticles with different shape to LNCaP and PC-3 prostate cancer cell lines. Cubic and spherical nanoparticles of magnetite were synthesized in organic medium and hydrophilized by non-ionic surfactant Pluronic F127—polyethylene-polypropylene oxide polymer. Doxoru...

Asialoglycoprotein receptor (ASGP-R) is a promising biological target for drug delivery into hepatoma cells. Nevertheless, there are only few examples of small-molecule conjugates of ASGP-R selective ligand equipped by a therapeutic agent for the treatment of hepatocellular carcinoma (HCC). In the present work, we describe a convenient and versatil...

Congenital diserythropoietic anemias are a group of rare inherited diseases causing une ective erythropoiesis and multiple morphological changes in erythroblasts. Their differential diagnosis involves a study of the morphology of minor bone marrow cell populations that requires a selective cell enrichment. Here we describe two methods of the popula...

We have studied how various drugs increasing the rate of nicotinic acetylcholine receptors (nAChRs) lateral diffusion affect the depression of ACh-induced current in land snail Helix lucorum neurons responsible for defensive behavior. The acetylcholine (ACh) iontophoretic application protocol imitated the behavioral habituation protocol for the int...

During a cell's lifespan, DNA break formation is a common event, associated with many processes, from replication to apoptosis. Most of DNA breaks are readily repaired, but some are meant to persist in time, such as the chromosome ends, protected by telomeres. Besides them, eukaryotic genomes comprise shorter stretches of interstitial telomeric rep...

Erythrocytes (RBCs) loaded with alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALD) can metabolize plasma ethanol and acetaldehyde but with low efficiency. We investigated the rate-limiting factors in ethanol oxidation by these enzymes loaded into RBCs. Mathematical modeling and in vitro experiments on human RBCs loaded simultaneously with...