Periodic hypoxia is a condition characterized by alternating episodes of oxygen deprivation (hypoxia) and periods of normal or elevated oxygen levels (reoxygenation). Depending on severity and duration of exposure, periodic hypoxia can activate both protective and pathological mechanisms. The aim of this study was to evaluate dependence of the effects of acute and periodic hypoxia on sex and age of rats. Male and female Wistar rats aged 2 and 4 months were used. The animals were exposed to normobaric hypoxia (8% O2, 2 h) either once or daily for 5 consecutive days. Subsequently, changes in body weight, activity and content of antioxidant system enzymes in blood plasma, as well as expression levels of the HIF-1α, GPx4, BDNF, and caspase-3 genes in the frontal cortex, hippocampus, and striatum of the brain were assessed. It was shown that daily hypoxia exposure leads to the decrease in body weight in both male and female rats of both ages. In the males, age-dependent changes in activity of antioxidant enzymes and increased expression of hypoxia marker genes in the brain were observed after a single hypoxia exposure. After multiple exposures, the recorded parameters did not differ from the control values. In the females, exposure to hypoxia did not affect activity of antioxidant enzymes, and increase in the expression of the studied genes was observed only after five daily exposures to hypoxia. The experiments revealed significant differences in the response to acute and periodic hypoxia exposure between male and female rats. These data should be considered when developing experimental models of periodic hypoxia and studying the mechanisms of adaptive and pathological reactions of the body to repeated hypoxia/reoxygenation episodes.
Allergic contact dermatitis (ACD) is a chronic inflammatory skin disorder the development of which is driven by allergen sensitization in peripheral lymphoid organs and local cutaneous inflammation. Lymphotoxin (LT) and its receptor LTβR are critical for lymphoid organogenesis and immune regulation in barrier tissues, but their role in ACD pathogenesis remains incompletely defined. This study aimed to delineate differential contribution of the LTβR-dependent signaling in oxazolone-induced dermatitis. We examined Lta knockout (Lta KO) mice, which lack both soluble LTα3 and membrane-bound isoforms LTα1β2/LTα2β1, and the Ltbr knockout (Ltbr KO) mice, both of which lack lymph nodes. ACD was induced by repeated oxazolone application to ear skin, with assessment of clinical severity, inflammation-associated gene expression, serum IgE levels, and immune cell composition in blood and spleen. Contrary to previous reports, the Lta KO mice developed dermatitis comparable to the wild-type (WT) mice, with elevated IgE production. In contrast, the Ltbr KO mice were substantially protected from the disease, exhibiting attenuated clinical inflammation, reduced ear swelling, and decreased Tslp expression in the lesional skin at the background of a lower proportion of circulating CD4+ T cells. These findings indicate that LTβR-dependent signaling is pathogenic in allergic skin inflammation, while LTα-mediated pathways are dispensable, suggesting a potential role for the other LTβR ligand, LIGHT, in ACD pathogenesis. Notably, ACD developed even in the absence of lymph nodes, highlighting the importance of local, skin-resident LTβR-dependent mechanisms in the disease development.
In recent years, targeted proteolysis systems have emerged as powerful tools for directed degradation of pathogenic proteins, offering novel therapeutic strategies for cancer, neurodegenerative disorders, and infectious diseases. This review systematizes key mechanisms and recent advances in inducible targeted proteolysis, including targeted proteasomal degradation (PROTACs, AbTACs, molecular glues), lysosome-mediated degradation (LYTACs, AUTACs, ATTECs) via endocytosis or autophagy, and targeted proteolysis in bacteria (BacPROTACs), which extends degradation technologies to prokaryotic systems. The structural features, advantages, and limitations of each platform are discussed in detail, along with key publications demonstrating their preclinical and clinical efficacy. Special attention is given to the prospects for translating these technologies into therapeutics, including overcoming challenges such as selectivity and in vivo delivery.
This article reviews biosynthesis of the valuable fat-soluble compounds with antioxidant activity, in particular vitamin E isomers and carotenoids, in yeast cells. Main genetic engineering approaches to increase microbial production of these substances are described. The main innovative strategies for subcellular separation of synthesis, storage, and recovery of lipophilic compounds are discussed, and examples of cell morphology engineering importance of are shown.
This review has considered the mechanisms of intracellular and intercellular signaling regulation by myeloperoxidase (MPO), an enzyme in neutrophil azurophilic granules, during oxidative/halogenative stress and inflammation development. The stages of enzyme functioning and the formation of reactive halogen species are described. The functioning of MPO and production of reactive halogen species are shown to depend on the activity of NADPH oxidase; the role of NADPH oxidase and reactive oxygen species in the regulation of MPO function is discussed. Particular attention is focused on the role of biological molecules modified by reactive halogen species in modulating NADPH oxidase activity, exocytosis of granular proteins, NETosis, and other neutrophil functions, based on the principle of positive feedback. A special feature of the review is the discussion of the non-canonical function of MPO, namely its signaling role in the regulation of cellular processes, which is not associated with the catalytic activity of the enzyme.
This review examines the key pathways of bidirectional communication between the gut and brain along the microbiota-gut-brain axis, with particular emphasis on the effects of metabolites of lactic acid bacteria (metLABs) on neurons of the enteric and central nervous systems. Special attention is given to the role of metLABs in intracellular signaling. The review further explores the direct effects of metLABs on mitochondrial function in nervous tissue, neuronal plasticity, and neuritogenesis. Potential mechanisms for the release of neurotrophic factors in both cells and host organism following exposure to metLABs or probiotic products are analyzed. Although clinical evidence remains limited, existing studies suggest that regular consumption of metLAB-containing fermented foods may positively influence brain functions through modulation of the microbiota-gut-brain axis. At least two ongoing clinical trials currently investigate whether normalization of the gut microbiota through probiotic interventions can slow the progression of Alzheimer's disease. As this field continues to advance rapidly, further studies are expected to provide important insights into the therapeutic potential of microbiota-targeted strategies for neurological health.
The pathophysiology of type 2 diabetes (T2D) remains poorly understood, largely because multiple early changes are obscure as they evolve during prolonged period of prediabetes. These changes are interconnected, involve feedback loops, and gradually develop in tissue-specific manner, ultimately leading to manifestation as overt diabetes. Insulin resistance (IR) and pancreatic β-cell dysfunction are regarded as central events driven by lipotoxicity and glucotoxicity. Understanding molecular mechanisms of their causes and consequences is essential for developing effective preventive and therapeutic strategies for T2D. This review describes the evolution of current perspectives on T2D pathophysiology, examines the mechanistic roles of lipotoxicity and glucotoxicity, and integrates current concepts on the molecular basis of IR. The hypotheses on the early events in prediabetes and potential role of IR in their progression toward overt T2D are discussed. A deeper understanding of T2D as a metabolic disease of biochemical origin may provide new insights into T2D prevention and major associated mortality risks, including cardiovascular complications and cancer.
Fluorescent proteins (FP) are widely used to visualize biological processes in living cells, including their use as genetically encoded markers for molecular and cellular research. However, their expression, even at the cellular level, could lead to some difficulties in interpreting molecular events due to protein-cell interactions. At the level of immunocompetent organisms, immune mechanisms could also take place, complicating the work with the cells expressing fluorescent proteins and interpretation of the experimental results. This led to the study of immunogenicity of FPs in the models of various diseases, in particular, cancer, and development of the models exhibiting immune tolerance to FP. This review describes various approaches for selecting disease models that are more immunotolerant to the expression of fluorescent proteins, and for reducing immunogenicity of both FP-expressing tumor models and some other diseases models. It highlights the ways to use the increased immunogenicity of the fluorescent tumors in experimental oncology, as well highlights some aspects of reducing immunogenicity of the fluorescent proteins exogenously administered to laboratory animals.
Pathological aggregation of α-synuclein is a key event in the development of synucleinopathies, such as Parkinson's disease and Lewy body dementia. Currently, no effective disease-modifying therapy is available, necessitating the search for new therapeutic agents. One promising strategy involves the use of low-molecular-weight compounds capable of inhibiting the formation of toxic protein aggregates. This study evaluates the anti-aggregation properties of EC3222x, a conjugate of pharmacophoric fragments of amantadine and a fluorinated derivative of tetrahydro-γ-carboline. α-Synucleinopathy was modeled in the SH-SY5Y neuroblastoma cell line by transfection with a plasmid vector encoding the mutant human α-synuclein A53T protein. EC3222x at a concentration of 1 µM reduced the number of cells with α-synuclein A53T aggregates. Its efficacy was comparable to that of SynuClean-D and Buntanetap, known inhibitors of α-synuclein aggregation. Treatment with EC3222x reduced both the level of diffusely distributed intracellular α-synuclein and the formation of mature fibrillar aggregates and large aggresomes. Importantly, EC3222x did not affect the accumulation of another aggregation-prone protein, TDP-43, in a similar cellular model, indicating its specificity for α-synuclein. These findings suggest that EC3222x may represent a promising candidate for the development of therapeutic agents targeting synucleinopathies.
Circular RNAs (circRNAs) are a unique class of covalently closed molecules formed through non-canonical splicing and characterized by a markedly greater stability compared to linear RNAs. Although the first circRNA was discovered half a century ago in 1976 in a viroid, they had remained largely overlooked for several decades. Over the past ten years, the however, interest in circRNAs has grown substantially, even as their biological functions and overall significance continue to be debated. It is now well established that circRNAs constitute a large and diverse group of molecules with varied origins and properties. They have been identified across a wide range of organisms, from prokaryotes to plants and mammals, where they participate in the regulation of numerous cellular processes. The unique properties of circRNAs are beginning to be exploited for practical applications, including their use as disease biomarkers and platforms for the development of novel therapeutic strategies. This review summarizes the knowledge accumulated on circRNAs since their discovery and highlights recent advances in understanding their biology and potential applications.
The mechanism of selective specificity of oxidoreductases to NAD+ or NADP+ and the ability to change the coenzyme specificity of these enzymes are some of the most important fundamental and applied problems. The first work on the switch in the coenzyme specificity from NADP+ to NAD+ was performed in 1990 for glutathione reductase. In 1993, formate dehydrogenase (FDH, EC 1.2.1.2) from the methylotrophic bacterium Pseudomonas sp. 101 (PseFDH) became the first oxidoreductase whose coenzyme specificity was changed in the opposite direction - from NAD+ to NADP+. Mutant NADP+-specific FDHs are extensively used in fine organic synthesis (including production of chiral compounds). The switch in the coenzyme specificity from NAD+ to NADP+ in FDHs is achieved by substituting amino acids at positions 198, 221, 222, 260, 379, and 380 (numbering according to PseFDH); however available data do not allow the interpretation of the exact role of each individual substitution. Since 2010, five natural NADP+-dependent FDHs have been found. In 2015-2024, three 3D structures for two natural and four 3D structures for two mutant NADP+-specific FDHs have appeared in the Protein Data Bank (PDB). In this review, we briefly discussed the general principles of coenzyme specificity based on the experimental and modeled FDH structures and performed a detailed analysis of the type and arrangement of residues at positions corresponding to His379 and Ser380 in PseFDH, whose role in NADP+ binding is still debated.
The deleterious role of oxidative stress in liver damage is a growing problem, and effective therapeutic interventions are highly warranted. This study evaluated whether peroxisome proliferator-activated receptor gamma (PPARγ) activation protects against H2O2-induced oxidative stress and apoptosis in human L02 hepatocytes. Cells pretreated with rosiglitazone, a PPARγ agonist, were incubated with H2O2, and cell viability was assessed using CCK8 and LDH release assays 24 h after the treatment. The content of apoptotic cells was determined using Hoechst 33258 staining, and the levels of apoptosis-related proteins were determined by immunoblotting. In addition, several oxidative stress indicators were measured. Possible involvement of the nuclear factor erythroid 2-related factor (Nrf2) pathway was investigated using the Nrf2 inhibitor ML385. Rosiglitazone (20 μM) increased cell viability and improved nuclear morphology in H2O2-treated L02 cells, possibly by increasing the Bcl-2/Bax ratio and reducing caspase-3 activation. Rosiglitazone also decreased reactive oxygen species and malonaldehyde levels, as well as increased the activities of catalase, glutathione peroxidase, and superoxide dismutase. Rosiglitazone also promoted nuclear translocation of Nrf2 and increased the antioxidant levels in H2O2-treated L02 cells. Inhibition of the Nrf2 pathway by ML385 partially abolished the rosiglitazone-induced amelioration of oxidative stress and apoptosis. We conclude that activation of PPARγ protects liver cells against oxidative stress and apoptosis through the Nrf2 pathway.
Psychoemotional disorders such as depression and anxiety are associated with adverse life experiences, but the precise mechanisms underlying the induction of psychopathologies, particularly anxiety, remain unclear. Among the wide range of biological alterations triggered by stressors, two systems - the hypothalamic-pituitary-adrenocortical (HPA) axis and the immune system - have been most extensively studied. Activation of the HPA axis leads to a rapid increase in glucocorticoids (cortisol in humans and corticosterone in rodents), which play a central role in coordinating adaptive stress responses. However, this increase can also lead to the development of psychopathologies. Elevated levels of peripheral and central proinflammatory cytokines have been reported in both patients with anxiety symptoms and laboratory animals. Elucidating the contribution of immune and glucocorticoid responses to stress-related behavioral outcomes is complicated by complex and bidirectional interactions between these systems. While corticosterone, consistent with the well-established immunosuppressive activity of glucocorticoids, can exert anti-inflammatory effects, elevated levels of this hormone may also promote systemic inflammation by enhancing the production of proinflammatory cytokines. Conversely, cytokines can modulate HPA axis activity, further influencing stress responses. The review summarizes experimental evidence on the roles of glucocorticoid hormones and the key proinflammatory cytokine interleukin-1β (IL-1β), as well as their interactions, in the development of stress-induced anxiety. A better understanding of these mechanisms may help clarify the pathophysiology of anxiety disorders.
The TPO gene belongs to the group of genes responsible for the biosynthesis of thyroid hormones and encodes thyroid peroxidase, a key enzyme involved in this process. Mutations in these genes can result in thyroid dysfunction characterized by reduced levels of thyroid hormones. Hypothyroidism caused by TPO pathogenic variants typically presents as permanent hypothyroidism and is frequently associated with endemic goiter. This analytical review summarizes and systematizes data from the studies conducted in different regions of the world on mutations identified in the TPO gene in patients with hypothyroidism. Particular attention is given to mutations within structural and functional domains of thyroid peroxidase, which has a unique molecular architecture within its family.
Gradient hydrogels represent a unique class of biomaterials capable of mimicking the spatial heterogeneity of native tissues and providing targeted effects on cells through mechanical, chemical, and biophysical gradients. In recent years, numerous fabrication strategies have been developed to generate gradient hydrogels, including layer-by-layer formation, photopolymerization, microfluidic techniques, and 3D/4D printing. This review summarizes current methodologies for the characterization of gradient hydrogels and highlights their emerging biomedical applications, such as controlled drug delivery, tissue engineering, regenerative medicine, organ-on-chip systems, and soft bioelectronic devices. Furthermore, the review discusses critical challenges related to the protocol standardization, manufacturing scalability, integration with additive manufacturing technologies, and potential regulatory barriers.
Presynaptic nerve terminals contain a large number of vesicles filled with neurotransmitters, whose release ensures signal transmission from the presynaptic neuron to the postsynaptic cell. Despite their morphological homogeneity, synaptic vesicles (SVs) are functionally heterogeneous and are organized into distinct groups (pools) that differ in their ability for exocytosis and mobilization, recycling kinetics, and protein composition. In addition to the classic pools - the readily releasable pool (RRP), recycling pool, and reserve pool - other populations have been identified, including spontaneously recycling vesicles, vesicles of resting pool and superpool. Vesicles from different pools engage in different modes of exocytosis and endocytosis, and the extent of interpool mixing varies depending on the synapse type and physiological or pathological conditions. Changes in the organization of SV pools underlie multiple forms of synaptic plasticity. Furthermore, SV cycling is a target of several pharmacological agents, and its disruption plays a significant role in the pathogenesis of neurodegenerative diseases. This article is a systematic review of SV pools, their organizational features in central and peripheral synapses, and implications of changes in the structure of SV pools in synaptic plasticity, action of drugs, and development of neurological disorders.
The hypothalamic-pituitary-gonadal (HPG, gonadal) axis is responsible for regulating reproductive functions, and its activity is regulated by numerous hormones, including leptin and insulin. Their primary targets are hypothalamic neurons expressing gonadotropin-releasing hormone (GnRH), which regulate secretion of gonadotropins and, thus, control puberty and fertility. The key function of leptin and insulin in hypothalamus is to mediate functional relationship between the energy availability and expenditure, on the one hand, and reproduction, which is determined, in part, by the activity of GnRH neurons, on the other. The effects of leptin and insulin on the GnRH neurons are typically indirect and mediated through other hypothalamic neurons, providing more specialized, multi-level regulation of their activity. The targets of leptin and insulin are various types of kisspeptin (Kiss1)-expressing neurons, as well as neurons expressing proopiomelanocortin (POMC, a precursor of anorexigenic melanocortin peptides), and the orexigenic factors - agouti-related peptide (AgRP) and neuropeptide Y (NPY). The Kiss1- and POMC-expressing neurons positively regulate GnRH-neurons, while the AgRP/NPY neurons are primarily involved in their negative regulation. The effects of leptin and insulin on the Kiss1-, POMC-, and AgRP/NPY-neurons, and consequently on the GnRH-neurons and the HPG axis, depend on physiological state of the organism, including its metabolic status, puberty, and gender. These effects are significantly altered in obesity and type 2 diabetes mellitus, thereby contributing to etiology and pathogenesis of the associated reproductive disorders. This review focuses on the current state of knowledge on the roles of insulin- and leptin-mediated regulation of the hypothalamic HPG axis in health and disease, as well as on the unresolved issues in this area. Understanding molecular basis of this regulation opens up broad prospects for the development of new pharmacological approaches to restoring reproductive function in obesity and diabetes.
Sphingosine-1-phosphate (S1P) is one of the most extensively studied bioactive signaling molecules of sphingolipid metabolism, which plays a pivotal role in regulating numerous processes in the central nervous system and immune system. Acting as an extracellular ligand for five subtypes of G-protein-coupled receptors (S1PR1-S1PR5) as well as an intracellular metabolic mediator, S1P controls lymphocyte migration, blood-brain barrier permeability, survival and differentiation of oligodendrocytes, reactivity of astrocytes and microglia, and balance between inflammation, neurodegeneration, and neuroprotection. In pathogenesis of the demyelinative diseases, particularly multiple sclerosis, disruption of the "sphingolipid rheostat" is observed - a shift toward predominance of pro-apoptotic ceramides and relative decrease in the S1P levels, which promotes prevalence of the neuroinflammatory and neurodegenerative processes over remyelination. This review summarizes current data on the structure, metabolism, and intra- and extracellular signaling pathways of S1P, its dual role under physiological conditions and in multiple sclerosis, and analyzes approaches to pharmacological modulation of S1P signaling pathways, highlighting the prospects of selective targeted therapy aimed at immunomodulation, neuroprotection, and stimulation of remyelination.
Major histocompatibility complex class I (MHC I) plays a crucial role in immune functions. This complex typically binds short fragments of protein chains, 8-9 amino acid residues in length, referred to as epitopes. In this study, we investigated differences between the peptides that bind to this complex (dataset N1) and those that do not (dataset N0). To compare the datasets N1 and N0, Z-score analysis using the Z-score function was applied to identify statistically significant differences in physicochemical properties under study: aliphatic index (αi), charge (Zi), hydrophobicity (Hi), isoelectric point (pIi), molecular weight (Mi), and instability index (IIi). All properties except for the instability index depend solely on amino acid composition of the peptides and not on the sequence-specific features. For the evaluated physicochemical properties, the Z-score values indicated no significant differences between the datasets N1 and N0. Maximum Z-score values were 0.30 for the aliphatic index and 0.29 for hydrophobicity. The most robust and reliable separation between the datasets N1 and N0 was achieved using the r-value method, yielding classification accuracy of approximately 70% and Z-score of 0.63. This result is close to the separation accuracy of 75% obtained using the MHCflurry program. Analysis of amino acid distributions in the datasets N1 and N0 showed that the residues such as tyrosine, phenylalanine, isoleucine, leucine, and valine occur more frequently than cysteine, tryptophan, arginine, and lysine in the octa- and nonapeptide epitopes that noncovalently bind to MHC class I. Using bioinformatics analysis and artificial intelligence approaches, we demonstrated the extent to which binding and non-binding peptides can be discriminated based solely on amino acid composition.
Insulin exerts a complex effect on metabolism, cell growth, and differentiation interacting with its receptor. Adipose tissue is one of the key targets for insulin; in this tissue insulin regulates the processes of energy storage, as well as tissue renewal and emergence of new adipocytes. Insulin activates conversion of glucose into fatty acids, inhibits lipolysis, and induces adipogenic differentiation of adipose tissue stem cells. The insulin receptor is a classic tyrosine kinase receptor that activate phosphoinositide-3-kinase and mitogen-activated protein kinase signaling cascades. At the same time, insulin receptor activates several non-canonical signaling cascades that determine features of the receptor functioning. For example, insulin can affect phosphoinositide metabolism, as well as calcium and redox-dependent signaling. In addition, the insulin receptor can also interact with the trimeric G proteins-coupled receptors (GPCRs). Here, we review canonical and non-canonical signaling cascades activated by the insulin receptor and molecular mechanisms of their involvement in regulating the human adipose tissue renewal.