ADF/cofilins form a family of small, widely expressed actin-binding proteins, regulating actin dynamics in various cellular and physiological processes in all eukaryotes, from yeasts to animals. Changes in the expression of the ADF/cofilin family proteins have been demonstrated under various pathological conditions. The well-established role of cofilin in migration, invasion, epithelial-mesenchymal transition, apoptosis, resistance to radiotherapy and chemotherapy, immune escape, and transcriptional dysregulation in malignant tumors is primarily attributed to its actin-modifying activity. Moreover, drugs targeting this function of cofilin have been developed for cancer treatment. However, its multilevel regulation, highly diverse effects across various pathological conditions, and conflicting data on the functional consequences of altered cofilin expression have prompted us to explore additional roles of cofilin—beyond actin modulation—particularly its involvement in lipid metabolism and mitochondrial homeostasis. Here, we review recent data on the expression of ADF/cofilin family proteins in various pathologies, account for the mutations and post-translational modifications of these proteins and their functional consequences, dwell on the role of K63-type ubiquitination of cofilin for its involvement in lipid metabolism and mitochondrial homeostasis, more specifically, a process of mitochondrial division or mitofission, point out conflicting data in cofilin research, and describe prospects for future studies of cofilin functions.

People who use drugs (PWUD) are at a high risk of contracting and developing severe coronavirus disease 2019 (COVID-19) and other infectious diseases due to their lifestyle, comorbidities, and the detrimental effects of opioids on cellular immunity. However, there is limited research on vaccine responses in PWUD, particularly regarding the role that T cells play in the immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Here, we show that before vaccination, PWUD did not exhibit an increased frequency of preexisting cross-reactive T cells to SARS-CoV-2 and that, despite the inhibitory effects that opioids have on T-cell immunity, standard vaccination can elicit robust polyfunctional CD4+ and CD8+ T-cell responses that were similar to those found in controls. Our findings indicate that vaccination stimulates an effective immune response in PWUD and highlight targeted vaccination as an essential public health instrument for the control of COVID-19 and other infectious diseases in this group of high-risk patients.

Poor overall survival of hematopoietic stem cell transplantation (HSCT) recipients who developed COVID-19 underlies the importance of SARS-CoV-2 vaccination. Previous studies of vaccine efficacy have reported weak humoral responses but conflicting results on T cell immunity. Here, we have examined the relationship between humoral and T cell response in 48 HSCT recipients who received two doses of Moderna’s mRNA-1273 or Pfizer/BioNTech’s BNT162b2 vaccines. Nearly all HSCT patients had robust T cell immunity regardless of protective humoral responses, with 18/48 (37%, IQR 8.679-5601 BAU/mL) displaying protective IgG anti-receptor binding domain (RBD) levels (>2000 BAU/mL). Flow cytometry analysis of activation induced markers (AIMs) revealed that 90% and 74% of HSCT patients showed reactivity towards immunodominant spike peptides in CD8 + and CD4 + T cells, respectively. The response rate increased to 90% for CD4 + T cells as well when we challenged the cells with a complete set of overlapping peptides spanning the entire spike protein. T cell response was detectable as early as 3 months after transplant, but only CD4 + T cell reactivity correlated with IgG anti-RBD level and time after transplantation. Boosting increased seroconversion rate, while only one patient developed COVID-19 requiring hospitalization. Our data suggest that HSCT recipients with poor serological responses were protected from severe COVID-19 by vaccine-induced T cell responses.

During the COVID-19 pandemic we utilized an AI-driven T cell epitope prediction tool, the NEC Immune Profiler (NIP) to scrutinize and predict regions of T cell immunogenicity (hotspots) from the entire SARS-CoV-2 viral proteome. These immunogenic regions offer potential for the development of universally protective T cell vaccine candidates. Here, we validated and characterized T cell responses to a set of minimal epitopes from these AI-identified universal hotspots. Utilizing a flow cytometry-based T cell activation-induced marker (AIM) assay, we identified 59 validated screening hits, of which 56% (33 peptides) have not been previously reported. Notably, we found that most of these novel epitopes were derived from the non-spike regions of SARS-CoV-2 (Orf1ab, Orf3a, and E). In addition, ex vivo stimulation with NIP-predicted peptides from the spike protein elicited CD8+ T cell response in PBMC isolated from most vaccinated donors. Our data confirm the predictive accuracy of AI platforms modelling bona fide immunogenicity and provide a novel framework for the evaluation of vaccine-induced T cell responses.

The aim Was to study the role of post-translational modifications of cofilin in the regulation of respiration and autophagy in murine brain mitochondria.MATERIALS AND METHODS:The experiments were performed with C57BL/6 mice. To obtain cytoplasmic and mitochondrial fractions of the brain tissue, differential centrifugation was used. Expressions of cofilin, phospho-cofilin, K48- and K63-associated chains of ubiquitin, and the autophagy marker LC3B were determined using electrophoresis, immunoprecipitation and Western blot methods. To study the processes of ubiquitination, we used PR619 - the inhibitor of deubiquitinating enzymes. Respiratory activity of brain mitochondria was evaluated using high-resolution fluorespirometry.RESULTS:Modification of cofilin by non-canonical K63 multiubiquitin chains in the cytoplasm and mitochondria from murine brain was demonstrated. Different levels of phospho-cofilin, cofilin, and its ubiquitinated proteoforms were found. PR619, the inhibitor of deubiquitinating enzymes, affects the expression of phosphorylated and ubiquitinated forms of cofilin in the mitochondria and cytoplasm, at the same time it changes the activity of tissue respiration and mitophagy.CONCLUSION:The sensitivity of cofilin to the inhibitor of deubiquitinating enzymes indicates the existence of a new non-catabolic mechanism of cofilin modification, which may be involved in the regulation of mitochondrial functions, specifically, the mitochondrial respiration and autophagy. The data help understand the molecular mechanisms of mitochondrial function in normal and pathological conditions, which may be useful in developing novel methods for the treatment of diseases of the nervous system.

The ubiquitin-proteasome system is a major protein degradative pathway involved in the maintenance of cellular structure and function. Actin cytoskeleton plays a critical role in the morphology and structural changes of the nerve cells. Cofilin is a main regulator of actin filament assembly/disassembly. Many diseases of the nerve system are associated with actin-cofilin remodeling. Nevertheless, the role of ubiquitylation in the regulation of cofilin activity and actin cytoskeleton structure in the nerve cells is little investigated. Confocal fluorescence microscopy-based methods are valuable tools for the precise imaging and quantitative evaluation of actin cytoskeleton changes. The aim of this research was to analyze the effect of a proteasome inhibitor MG132 on actin cytoskeleton remodeling in the nerve cells using fluorescence imaging. Cofilin was shown to be colocalized with actin filaments and ubiquitin in hippocampal cells. Analysis of cofilin proteoforms revealed the presence of cofilin modified by K63-linked multiubiquitin chains. The treatment of hippocampal cells with MG132 led to the changes in the structure of actin cytoskeleton, expression of cofilin, and activation of autophagy. Therefore, the results suggest the relationship between cofilin ubiquitylation and actin cytoskeleton remodeling in the nerve cells. It may be important for the development of new methods of diagnosis and treatment of the nerve system disorders.

It is well-known that hyaluronic acid (HA) as a component of brain extracellular matrix (ECM) plays a pivotal role in the nervous system and is involved in synaptic plasticity changes in vascular cognitive impairment and dementia. HA breakdown is a feature of the acute stage of stroke injury and may be detrimental through enhancement of the inflammatory response. Recent studies have shown that knockout mice lacking hyaluronic acid synthetase demonstrates epileptic phenotype in vivo and removal of HA leads to delayed development of epileptiform activity in cultured hippocampal neurons in vitro. Here, we studied whether digestion of hyaluronic acid in the hippocampus in early postnatal period can trigger seizures. Hyaluronidase (Hyal) (5 U/μl) was bilaterally injected into C57BL/6j mice (P17) CA1 field of hippocampus using the stereotaxic method to remove hyaluronan-based ECM. Transcriptome analysis of hippocampal tissue 2 h after enzymatic digestion of hyaluronan-based brain ECM revealed increased gene expression of proteins involved in inflammation reactions (TLR2, CCL2,3,5), neuroinflammation, axonal guidance and ephrin receptor signaling, versus the vehicle group. Mice injected with hyaluronidase exhibited delayed audiogenic seizures and improvement in working memory 72 h after injection, while there were no changes in locomotor activity, anxious level and exploratory behavior due to the open field test. The obtained results point to a link between the activation of neuroinflammation by enzymatic digestion of hyaluronan-based brain ECM during the neonatal period and their subsequent reactivity to seizures, which may play an important role in the functional features of the developing brain, including its seizure propensity.

Actin-binding proteins and, in particular, members of the actin-depolymerization factor (ADF)/cofilin family, are involved in the regulation of the actin cytoskeleton in response to various intracellular and extracellular signals. Recent studies point to the exceptional role of this group of proteins in the development and functioning of the nervous system. This review presents the latest data on the functions of cofilin in the cell and the signaling pathways involved in its regulation. Special attention is paid to studies of the relationship between cofilin and actin dynamics in such processes as the control of synaptic plasticity, apoptosis of neurons, and neuroinflammation. We show the molecular mechanisms of cofilin activation-inactivation and the specific structure of actin in nerve cells during neurodegeneration in the in vitro and in vivo models. We review new directions in the study of cofilin and related proteins as prognostic markers and therapeutic targets in the diagnosis and treatment of diseases of the nervous system.

The aim of the study is to analyze the entire set of proteins (proteome) expressed in the endometrial tissue and to identify protein markers specific for carcinogenesis. according to trypsin standard Obtained tryptic peptides analyzed and identified by high-performance liquid chromatography coupled with tandem mass spectrometry.The Human Protein Atlas and Tissue-Specific Gene Expression and Regulation databases were used to analyze the tissue-specific protein expression. on their potential involvement in carcinogenesis. The obtained data can serve as the starting point for further in-depth studies of the endometrium using the proteomic approach, as well as other OMICS technologies. Subsequent application of bioinformatic tools will allow revealing of molecular mechanisms of relationship between inflammation and endometrium tissue malignant transformation.

Expression of cofilin is directly associated with metastatic activity in many tumors. Here, we studied the role of Latent Membrane Protein 2 A (LMP2A) of Epstein-Barr Virus (EBV) in the accumulation of cofilin observed in nasopharyngeal cancer (NPC) tumor cells. We used LMP2A transformed NPC cell lines to analyze cofilin expression. We used mutation analysis, ectopic expression and down-regulation of Cbl, AIP4 and Syk in these cell lines to determine the effect of the LMP2A viral protein on cofilin degradation and its role in the assembly of a cofilin degrading protein complex. The LMP2A of EBV was found to interfer with cofilin degradation in NPC cells by accelerating the proteasomal degradation of Cbl and Syk. In line with this, we found significantly higher cofilin expression in NPC tumor samples as compared to the surrounding epithelial tissues. Cofilin, as an actin severing protein, influences cellular plasticity, and facilitates cellular movement in response to oncogenic stimuli. Thus, under relaxed cellular control, cofilin facilitates tumor cell movement and dissemination. Interference with its degradation may enhance the metastatic potential of NPC cells.

Ubiquitylation, a widespread and important posttranslational modification of eukaryotic proteins, regulates a multitude of critical cellular processes, both in normal and pathological conditions. A classical view of how ubiquitylation regulates protein function involves recognition of ubiquitin-encoded signals by specific ubiquitin-binding domains. However, evidence suggests the existence of direct effects of ubiquitylation, which occur through its impact on protein-protein interactions that do not involve specific ubiquitin receptors. Ubiquitin attachment may cause steric limitations that influence interaction of the modified protein with other proteins. Here, we present examples of this direct effect of ubiquitylation and propose how a two-level ubiquitin-mediated regulatory mechanism may provide flexibility.

The catalytic properties of mitochondrial and cytoplasmic isoenzymes of NAD-dependent brain malate dehydrogenase (MDH) were studied under hypoxic or ischemic conditions. Hypoxia was modeled in animals in pressure chamber, while ischemia was achieved via bilateral ligation of common carotic arteries. The properties of MDH in mitochondria of rat brain were studied; they were significantly different from those of MDH purified from bovine brain. The study revealed the importance of mitochondrial membranes for the regulation of malate dehydrogenase catalytic properties in brain mitochondria. Cerebral ischemia changes mitochondrial malate dehydrogenase significantly, which demonstrates disorder in MDH-membrane interaction. Cytoplasmic enzyme displays high activity and stability of its catalytic properties. Under cerebral hypoxia or ischemia catalytic properties of cytoplasmic malate dehydrogenase change only slightly, maintaining enzyme activity at a constantly high level.

BACKGROUND:Post-translational protein modification with ubiquitin, or ubiquitylation, is one of the hottest topics in a modern biology due to a dramatic impact on diverse metabolic pathways and involvement in pathogenesis of severe human diseases. A great number of eukaryotic proteins was found to be ubiquitylated. However, data about particular ubiquitylated proteins are rather disembodied.DESCRIPTION:To fill a general need for collecting and systematizing experimental data concerning ubiquitylation we have developed a new resource, UbiProt Database, a knowledge base of ubiquitylated proteins. The database contains retrievable information about overall characteristics of a particular protein, ubiquitylation features, related ubiquitylation and de-ubiquitylation machinery and literature references reflecting experimental evidence of ubiquitylation. UbiProt is available at http://ubiprot.org.ru for free.CONCLUSION:UbiProt Database is a public resource offering comprehensive information on ubiquitylated proteins. The resource can serve as a general reference source both for researchers in ubiquitin field and those who deal with particular ubiquitylated proteins which are of their interest. Further development of the UbiProt Database is expected to be of common interest for research groups involved in studies of the ubiquitin system.

Delta sleep-inducing peptide is shown to alter properties of malate dehydrogenase in brain mitochondria. The regulatory activity of the peptide is manifested in stabilization of catalytic properties of the enzyme at a higher level, which prevents their change during hypoxic stress. Regulation of malate dehydrogenase is presumed to occur through direct action of the peptide on mitochondrial membranes.