Eukaryotic Research Articles

Thermosensory Spiking Activity of Proteinoid Microspheres Cross-Linked by Actin Filaments.

Actin, found in all eukaryotic cells as globular (G) or filamentous (F) actin, undergoes polymerization, with G-actin units changing shape to become F-actin. Thermal proteins, or proteinoids, are created by heating amino acids (160-200 °C), forming polymeric chains. These proteinoids can swell in an aqueous solution at around 50 °C, producing hollow microspheres filled with a solution, exhibiting voltage spikes. Our research explores the signaling properties of proteinoids, actin filaments, and hybrid networks combining actin and proteinoids. Proteinoids replicate brain excitation dynamics despite lacking specific membranes or ion channels. We investigate enhancing conductivity and spiking by using pure actin, yielding improved coordination in networks compared with individual filaments or proteinoids. Temperature changes (20 short-peptide supramolecular C to 80 °C) regulate conduction states, demonstrating external control over emergent excitability in protobrain systems. Adding actin to proteinoids reduces spike timing variability, providing a more uniform feature distribution. These findings support theoretical models proposing cytoskeletal matrices for functional specification in synthetic protocell brains, promoting stable interaction complexity. The study concludes that life-like signal encoding can emerge spontaneously within biological polymer scaffolds, incorporating abiotic chemistry.

Partitioning to ordered membrane domains regulates the kinetics of secretory traffic.

The organelles of eukaryotic cells maintain distinct protein and lipid compositions required for their specific functions. The mechanisms by which many of these components are sorted to their specific locations remain unknown. While some motifs mediating subcellular protein localization have been identified, many membrane proteins and most membrane lipids lack known sorting determinants. A putative mechanism for sorting of membrane components is based on membrane domains known as lipid rafts, which are laterally segregated nanoscopic assemblies of specific lipids and proteins. To assess the role of such domains in the secretory pathway, we applied a robust tool for synchronized secretory protein traffic (RUSH, Retention Using Selective Hooks) to protein constructs with defined affinity for raft phases. These constructs consist solely of single-pass transmembrane domains (TMDs) and, lacking other sorting determinants, constitute probes for membrane domain-mediated trafficking. We find that while raft affinity can be sufficient for steady-state PM localization, it is not sufficient for rapid exit from the endoplasmic reticulum (ER), which is instead mediated by a short cytosolic peptide motif. In contrast, we find that Golgi exit kinetics are highly dependent on raft affinity, with raft preferring probes exiting the Golgi ~2.5-fold faster than probes with minimal raft affinity. We rationalize these observations with a kinetic model of secretory trafficking, wherein Golgi export can be facilitated by protein association with raft domains. These observations support a role for raft-like membrane domains in the secretory pathway and establish an experimental paradigm for dissecting its underlying machinery.

Bactericidal effect of tetracycline in E. coli strain ED1a may be associated with ribosome dysfunction

Ribosomes translate the genetic code into proteins. Recent technical advances have facilitated in situ structural analyses of ribosome functional states inside eukaryotic cells and the minimal bacterium Mycoplasma. However, such analyses of Gram-negative bacteria are lacking, despite their ribosomes being major antimicrobial drug targets. Here we compare two E. coli strains, a lab E. coli K-12 and human gut isolate E. coli ED1a, for which tetracycline exhibits bacteriostatic and bactericidal action, respectively. Using our approach for close-to-native E. coli sample preparation, we assess the two strains by cryo-ET and visualize their ribosomes at high resolution in situ. Upon tetracycline treatment, these exhibit virtually identical drug binding sites, yet the conformation distribution of ribosomal complexes differs. While K-12 retains ribosomes in a translation-competent state, tRNAs are lost in the vast majority of ED1a ribosomes. These structural findings together with the proteome-wide abundance and thermal stability assessments indicate that antibiotic responses are complex in cells and can differ between different strains of a single species, thus arguing that all relevant bacterial strains should be analyzed in situ when addressing antibiotic mode of action.

Tumour suppressor protein sMEK1 links to IRE1 signalling pathway to modulate its activity during ER stress

The Endoplasmic Reticulum is a pervasive, dynamic cellular organelle that performs a wide range of functions in the eukaryotic cell, including protein folding and maturation. Upon stress, ER activates an adaptive cellular pathway, namely Unfolded Protein Response, that transduces information from ER to nucleus, restoring homeostasis in the ER milieu. UPR consists of three membrane-tethered sensors; IRE1, PERK and ATF6. Among all the UPR sensors, the IRE1 branch acts as a central pathway that orchestrates several pathways to determine cell fate. However, the detailed knowledge underlying the whole process is not understood yet. Previously, we determined the sMEK1 as one of the interacting partners of IRE1. sMEK1 is a protein phosphatase, which has been indicated in a number of critical cellular functions like apoptosis, cell proliferation, and tumour suppression. In this study, we evaluated the role of sMEK1 on the IRE1 signalling pathway. Our data indicate that sMEK1 can inhibit IRE1 phosphorylation under ER stress. This inhibitory effect of sMEK1 could be reflected in its downstream effectors, Xbp1 and RIDD, which are downregulated in the presence of sMEK1. We also found that the repressing effect of sMEK1 was specific to the IRE1 signalling pathway and could be preserved even under prolonged ER stress. Our findings also indicate that sMEK1 can inhibit IRE1 and its downstream molecules under ER stress irrespective of other UPR sensors. These results help to draw the mechanistic details giving insights into different molecular connections of UPR with other pathways.

Mitochondrial genome complexity in Stemona sessilifolia: nanopore sequencing reveals chloroplast gene transfer and DNA rearrangements.

Mitochondria are semi-autonomous organelles in eukaryotic cells with their own genome. Plant mitogenomes differ from animal mitogenomes in size, structure, and repetitive DNA sequences. Despite larger sizes, plant mitogenomes do not have significantly more genes. They exhibit diverse structures due to variations in size, repetitive DNA, recombination frequencies, low gene densities, and reduced nucleotide substitution rates. In this study, we analyzed the mitochondrial genome of Stemona sessilifolia using Nanopore and Illumina sequencing. De-novo assembly and annotation were conducted using Unicycler, Geseq, tRNAscan-SE and BLASTN, followed by codon usage, repeat sequence, RNA-editing, synteny, and phylogenetic analyses. S. sessilifolia's mitogenome consisted of one linear contig and six circular contigs totaling 724,751bp. It had 39 protein-coding genes, 27 tRNA genes, and 3 rRNA genes. Transfer of chloroplast sequences accounted for 13.14% of the mitogenome. Various analyses provided insights into genetic characteristics, evolutionary dynamics, and phylogenetic placement. Further investigations can explore transferred genes' functions and RNA-editing's role in mitochondrial gene expression in S. sessilifolia.

The Promising Role of Selenium and Yeast in the Fight Against Protein Amyloidosis.

In recent years, increasing attention has been paid to research on diseases related to the deposition of misfolded proteins (amyloids) in various organs. Moreover, modern scientists emphasise the importance of selenium as a bioelement necessary for the proper functioning of living organisms. The inorganic form of selenium-sodium selenite (redox-active)-can prevent the formation of an insoluble polymer in proteins. It is very important to undertake tasks aimed at understanding the mechanisms of action of this element in inhibiting the formation of various types of amyloid. Furthermore, yeast cells play an important role in this matter as a eukaryotic model organism, which is intensively used in molecular research on protein amyloidosis. Due to the lack of appropriate treatment in the general population, the problem of amyloidosis remains unsolved. This extracellular accumulation of amyloid is one of the main factors responsible for the occurrence of Alzheimer's disease. The review presented here contains scientific information discussing a brief description of the possibility of amyloid formation in cells and the use of selenium as a factor preventing the formation of these protein aggregates. Recent studies have shown that the yeast model can be successfully used as a eukaryotic organism in biotechnological research aimed at understanding the essence of the entire amyloidosis process. Understanding the mechanisms that regulate the reaction of yeast to selenium and the phenomenon of amyloidosis is important in the aetiology and pathogenesis of various disease states. Therefore, it is imperative to conduct further research and analysis aimed at explaining and confirming the role of selenium in the processes of protein misfolding disorders. The rest of the article discusses the characteristics of food protein amyloidosis and their use in the food industry. During such tests, their toxicity is checked because not all food proteins can produce amyloid that is toxic to cells. It should also be noted that a moderate diet is beneficial for the corresponding disease relief caused by amyloidosis.

Using origami and Shrinky Dinks to create active learning activities to tackle two microbiology concepts: cell structure differences and operon regulation.

This paper presents two low-cost hands-on activities designed to enhance student understanding and address the pedagogical challenges faced by microbiology professors in teaching concepts related to cell structure and gene regulation. In the first activity, we used Shrinky Dinks and Jeopardy-style game questions to explore the differences between prokaryotic and eukaryotic cells. Students have to collect pieces and physically build their cell models. The second activity uses origami organelles sets from Edvotek to illustrate the regulation of gene expression in the lac and trp operons, incorporating mutation scenarios for analysis. The intended audience comprises undergraduate students in microbiology, including biology, pre-medical studies, and health profession majors. The activities were deployed in three microbiology lectures, and students were surveyed. Students' feedback highlights the efficacy of the hands-on approach and increased class participation, as two of the recurring words in the students' survey were "helpful" and "fun."

The Relationship of Mitochondrial-derived Peptide (MOTS-c) and Brain Mitochondrial Carrier Protein 1 (BMCP1) Response in Sheep with Some Physiological Parameters

Background: Mitochondria are organelles called power plants of the cell, which are found in eukaryotic cells and are responsible for the production of energy needed by the cells through aerobic respiration. Mitochondrial dysfunction causes endocrinological, cardiovascular, metabolic and neurodegenerative diseases. The aim of this study was to examine the effects of body condition score (BCS), lactation, pregnancy, age and gender on Mitochondrial-Derived Peptide (MOTS-c) and Brain Mitochondrial Transporter Protein 1 (BMCP1) levels in Akkaraman sheep. Methods: Sheep are classified into 3 categories according to BCS (BCS less than 2, BCS=3-3.5, BCS≥4). In creating groups in terms of BCS, it was determined by the palpation method applied to the waist area. The sheep included in the study were divided into 4 groups: early lactation, early pregnancy, late pregnancy (dry period) and age (female and male sheep).1st group, ewes in the first period of pregnancy (on the 100th day of the first pregnancy) (n = 30), 2nd group, ewes in the early lactation period (n = 30), 3rd group, ewes in the dry period (the last two months of pregnancy) (n = 30) and in the 4th group, less than 2 (young) (n=30), 2-8 (adult) (n=30), 8 greater than (old) (n=30), male and female sheep (n=30) of different ages. =180) total of 270 animals. Blood samples were taken from the jugular vein of the sheep before the morning feeding. MOTSc and BMCP1 levels were determined in blood serum samples by ELISA method. Result: In the study, serum MOTS-c and BMCP1 levels in sheep during lactation and pregnancy were determined to be lowest in the VKS less than 2 group and highest in the VKS≥4 groups. Likewise, in age and gender groups, the highest level was detected in young lambs and yearlings in the VKS less than 2 group, while the highest level was detected in old sheep and rams in the VKS≥4 group. As a result, it was determined that different age, gender, pregnancy and lactation periods affected serum MOTS-c and BMCP1 levels depending on the change in BCS (P less than 0.05). It was concluded that MOTS-c and BMCP1 may be useful parameters in the evaluation of mitochondrial function, energy metabolism and metabolic profile.

The m6A reader HNRNPC promotes glioma progression by enhancing the stability of IRAK1 mRNA through the MAPK pathway

Glioma is the most common and aggressive type of primary malignant brain tumor. The N6-methyladenosine (m6A) modification widely exists in eukaryotic cells and plays an important role in the occurrence and development of human tumors. However, the function and mechanism of heterogeneous nuclear ribonucleoprotein C (HNRNPC), an RNA-binding protein and m6A reader in gliomas remains to be comprehensively and extensively explored. Herein, we found that HNRNPC mRNA and protein overexpression were associated with a poor prognosis for patients with gliomas, based on the data from TCGA, the CGGA, and the TMAs. Biologically, HNRNPC knockdown markedly repressed malignant phenotypes of glioma in vitro and in vivo, whereas ectopic HNRNPC expression had the opposite effect. Integrative RNA sequencing and MeRIP sequencing analyses identified interleukin-1 receptor-associated kinase 1 (IRAK1) as a downstream target of HNRNPC. The glioma public datasets and tissue microarrays (TMAs) data indicated that IRAK1 overexpression was associated with poor prognosis, and IRAK1 knockdown significantly repressed malignant biological behavior in vitro. Mechanistically, HNRNPC maintains the mRNA stability of IRAK1 in an m6A-dependent manner, resulting in activation of the mitogen-activated protein kinase (MAPK) signaling pathway, which was necessary for the malignant behavior of glioma. Our findings demonstrate the HNRNPC–IRAK1–MAPK axis as a crucial carcinogenic factor for glioma and the novel underlying mechanism of IRAK1 upregulation, which provides a rationale for therapeutically targeting epitranscriptomic modulators in glioma.

PDZD8-FKBP8 tethering complex at ER-mitochondria contact sites regulates mitochondrial complexity.

Mitochondria-ER membrane contact sites (MERCS) represent a fundamental ultrastructural feature underlying unique biochemistry and physiology in eukaryotic cells. The ER protein PDZD8 is required for the formation of MERCS in many cell types, however, its tethering partner on the outer mitochondrial membrane (OMM) is currently unknown. Here we identified the OMM protein FKBP8 as the tethering partner of PDZD8 using a combination of unbiased proximity proteomics, CRISPR-Cas9 endogenous protein tagging, Cryo-Electron Microscopy (Cryo-EM) tomography, and correlative light-EM (CLEM). Single molecule tracking revealed highly dynamic diffusion properties of PDZD8 along the ER membrane with significant pauses and capture at MERCS. Overexpression of FKBP8 was sufficient to narrow the ER-OMM distance, whereas independent versus combined deletions of these two proteins demonstrated their interdependence for MERCS formation. Furthermore, PDZD8 enhances mitochondrial complexity in a FKBP8-dependent manner. Our results identify a novel ER-mitochondria tethering complex that regulates mitochondrial morphology in mammalian cells.

Methods and computational tools to study eukaryotic cell migration in vitro.

Cellular movement is essential for many vital biological functions where it plays a pivotal role both at the single cell level, such as during division or differentiation, and at the macroscopic level within tissues, where coordinated migration is crucial for proper morphogenesis. It also has an impact on various pathological processes, one for all, cancer spreading. Cell migration is a complex phenomenon and diverse experimental methods have been developed aimed at dissecting and analysing its distinct facets independently. In parallel, corresponding analytical procedures and tools have been devised to gain deep insight and interpret experimental results. Here we review established experimental techniques designed to investigate specific aspects of cell migration and present a broad collection of historical as well as cutting-edge computational tools used in quantitative analysis of cell motion.

Bioinformatics Analysis of Actin Interactome: Characterization of the Nuclear and Cytoplasmic Actin-Binding Proteins.

Actin is present in the cytoplasm and nucleus of every eukaryotic cell. In the cytoplasm, framework and motor functions of actin are associated with its ability to polymerize to form F-actin. In the nucleus, globular actin plays a significant functional role. For a globular protein, actin has a uniquely large number of proteins with which it interacts. Bioinformatics analysis of the actin interactome showed that only a part of actin-binding proteins are both cytoplasmic and nuclear. There are proteins that interact only with cytoplasmic, or only with nuclear actin. The first pool includes proteins associated with the formation, regulation, and functioning of the actin cytoskeleton predominate, while nuclear actin-binding proteins are involved in the majority of key nuclear processes, from regulation of transcription to DNA damage response. Bioinformatics analysis of the structure of actin-binding proteins showed that these are mainly intrinsically disordered proteins, many of which are part of membrane-less organelles. Interestingly, although the number of intrinsically disordered actin-binding proteins in the nucleus is greater than in the cytoplasm, the drivers for the formation of the membrane-less organelles in the cytoplasm are significantly (four times) greater than in the nucleus.

Novel Z-DNA binding domains in giant viruses

Z-nucleic acid structures play vital roles in cellular processes and have implications in innate immunity due to their recognition by Zα domains containing proteins (Z-DNA/Z-RNA binding proteins, ZBPs). Although Zα domains have been identified in six proteins, including viral E3L, ORF112, and I73R, as well as, cellular ADAR1, ZBP1, and PKZ, their prevalence across living organisms remains largely unexplored. In this study, we introduce a computational approach to predict Zα domains, leading to the revelation of previously unidentified Zα domain-containing proteins in eukaryotic organisms, including non-metazoan species. Our findings encompass the discovery of new ZBPs in previously unexplored giant viruses, members of the Nucleocytoviricota phylum. Through experimental validation, we confirm the Zα functionality of select proteins, establishing their capability to induce the B-to-Z conversion. Additionally, we identify Zα-like domains within bacterial proteins. While these domains share certain features with Zα domains, they lack the ability to bind to Z-nucleic acids or facilitate the B-to-Z DNA conversion. Our findings significantly expand the ZBP family across a wide spectrum of organisms and raise intriguing questions about the evolutionary origins of Zα-containing proteins. Moreover, our study offers fresh perspectives on the functional significance of Zα domains in virus sensing and innate immunity and opens avenues for exploring hitherto undiscovered functions of ZBPs.

A self-complementary AAV proviral plasmid that reduces cross-packaging and ITR promoter activity in AAV vector preparations

Adeno-associated viral vectors (AAV) are a leading delivery system for gene therapy in animal models and humans. With several FDA-approved AAV gene therapies on the market, issues related to vector manufacturing have become increasingly important. In this study, we focused on potentially toxic DNA contaminants that can arise from AAV proviral plasmids, the raw materials required for manufacturing recombinant AAV in eukaryotic cells. Typical AAV proviral plasmids are circular DNAs containing a therapeutic gene cassette flanked by natural AAV inverted terminal repeat (ITR) sequences, and a plasmid backbone carrying prokaryotic sequences required for plasmid replication and selection in bacteria. While the majority of AAV particles package the intended therapeutic payload, some capsids instead package the bacterial sequences located on the proviral plasmid backbone. Since ITR sequences also have promoter activity, potentially toxic bacterial open reading frames can be produced in vivo, thereby representing a safety risk. In this study, we describe a new AAV proviral plasmid for vector manufacturing that (1) significantly decreases cross-packaged bacterial sequences; (2) increases correctly packaged AAV payloads; and (3) blunts ITR-driven transcription of cross-packaged material to avoid expressing potentially toxic bacterial sequences. This system may help improve the safety of AAV vector products.

Effects of the glyphosate-based herbicide roundup on C. elegans and S. cerevisiae mortality, reproduction, and transcription fidelity

Glyphosate-based weed killers such as Roundup have been implicated in detrimental effects on single- and multicellular eukaryotic model organism health and longevity. However, the mode(s) of action for these effects are currently unknown. In this study, we investigate the impact of exposure to Roundup on two model organisms: Saccharomyces cerevisiae and Caenorhabditis elegans and test the hypothesis that exposure to Roundup decreases transcription fidelity. Population growth assays and motility assays were performed in order to determine the phenotypic effects of Roundup exposure. We also used Rolling-Circle Amplification RNA sequencing to quantify the impact of exposure to Roundup on transcription fidelity in these two model organisms. Our results show that exposure to the glyphosate-based herbicide Roundup increases mortality, reduces reproduction, and increases transcription error rates in C. elegans and S. cerevisiae. We suggest that these effects may be due in part to the involvement of inflammation and oxidative stress, conditions which may also contribute to increases in transcription error rates.

Exploring the Interplay between Nutrients, Bacteriophages, and Bacterial Lipases in Host- and Bacteria-mediated Pathogenesis.

Pathogenic bacteria and host cells counteract or neutralize each other's effect in two fundamental ways: Direct invasion and secretion of various substances. Among these, lipases secreted by pathogenic bacteria and host cell lysozyme are key actors. Secreted lipases from pathogenic bacterial are suggested as a key player in the pathogen-host interaction. Among the gut microbial energy sources, glucose and fats have been referred to as one of the best inducers and substrates for bacterial lipases. Enrichment of bacterial growth medium with extra glucose or oil has been shown to induce lipase production in pathogenic bacteria. More recently, research has focused on the role of human gut phage alterations in the onset of dysbiosis because the bacteria-phage interactions can be dramatically affected by the nutrient milieu of the gut. However, the reciprocal role of bacterial lipases and phages in this context has not been well studied and there is no data available about how high glucose or fat availability might modulate the cellular milieu of the pathogenic bacteria-phageeukaryotic host cell interface. The purpose of this study was to evaluate the immunologic outcome of pathogenic bacteria-phage interaction under normal, high glucose, and high butter oil conditions to understand how nutrient availability affects lipase activity in pathogenic bacteria and, ultimately, the eukaryotic host cell responses to pathogenic bacteria-phage interaction. 10 groups of co-cultured T84 and HepG2 cells were treated with Pseudomonas aeruginosa strain PAO1 (P.a PAO1) in the presence and absence of its KPP22 phage and incubated in three different growth media (DMEM, DMEM + glucose and DMEM + butter oil). Structural and physiological (barrier function and cell viability), inflammatory (IL-6 and IL-8), metabolic (glucose and triglycerides), and enzymatic (lipases and lysozyme) parameters were determined. Excess glucose or butter oil enhanced additively extracellular lipase activity of P.a PAO1. Excess glucose or butter oil treatments also magnified P. a PAO1- induced secretion of inflammatory signal molecules (IL-1β, IL-6) from co-cultured cells, concomitant with the enhancement of intracellular triglycerides in co-cultured HepG2 cells, these effects being abolished by phage KPP22. The results of the present study imply that KPP22 phage influences the interplay between food substances, gut bacterial lipases, and the gut cellular milieu. This can be applied in two-way interaction: by affecting the microbial uptake of excess free simple sugars and fats from the gut milieu leading to decreased bacterial lipases and by modulating the immune system of the intestinal -liver axis cells. Further studies are needed to see if the biological consequences of these effects also occur in vivo.

Novel BRICHOS-related Defensin-like Antimicrobial Peptide from the Marine Polychaeta Arenicola marina

Objective: To date, polychaetes remain a poorly studied class of invertebrate animals in terms of the features of functioning of their immune system and, in particular, the biodiversity of antimicrobial peptides (AMPs). AMPs also known as host defense peptides play a key role in host protection from various pathogens and regulation of the species composition of symbiotic microbes. A study of the biosynthesis of AMPs in polychaetes resulted in the discovery of the so-called BRICHOS domain in the structure of the precursor proteins of a number of such peptides. The conserved structure of this domain makes possible the bioinformatic search for AMP precursors in polychaete transcriptomes. In this work, we found and studied a novel BRICHOS-related AMP from the lugworm Arenicola marina, representing a previously undiscovered in polychaetes a structural family of defensin-like peptides stabilized by four disulfide bonds. Methods: The peptide, designated as AmBRI-44a and containing 44 amino acid residues, was obtained by heterologous expression in Escherichia coli. The peptide secondary structure was investigated by CD spectroscopy in water and dodecylphosphocholine (DPC) micelles. The minimum inhibitory concentrations (MICs) against a wide range of bacterial pathogens were assessed using the two-fold serial dilutions method. Cytotoxicity of AmBRI-44a was studied in vitro on human erythrocytes or adherent cell line HEK293T using the hemoglobin release assay or the MTT test, respectively. The AMBRI-44a potential target was discovered by successive daily subculturing of the AmBRI-44a resistant strain followed by whole-genome sequencing. Results and Discussion: According to CD data, AmBRI-44a is a predominantly β-structured peptide. AmBRI-44a was shown to have a specific activity against a narrow spectrum of Gram-positive bacteria and pronounced cytotoxic effects on the eukaryotic cell line HEK293T. The proposed mechanism of the antibacterial action of this peptide is associated with the inhibition of bacterial cell wall biosynthesis, as indicated by the genetic and phenotypic analysis of selected AmBRI-44a-resistant bacteria Bacillus licheniformis B-511. Conclusions: The resulting data allow us to consider the discovered peptide AmBRI-44a as a candidate compound for the development of an antibiotic agent that could potentially be effective in the treatment of infectious diseases mediated by multidrug-resistant Gram-positive bacteria.

Advances in Polymeric Nanomaterial-mediated Autophagy for Cancer Therapy.

Autophagy is an important biological mechanism for eukaryotic cells to regulate growth, death, and energy metabolism, and plays an important role in removing damaged organelles, misfolded or aggregated proteins, and clearing pathogens. It has been found that autophagy is closely related to cell survival and death, and is of great significance in cancerigenesis and development, playing a bidirectional role in cancer inhibition and cancer promotion. Therefore, treating cancers by regulating autophagy has attracted much attention. A large amount of research evidence indicates that polymeric nanomaterials are able to regulate cellular autophagy, and their good biocompatibility, degradability, and functionalizable modification open up a broad application prospect for improving the therapeutic effect of cancers. This review provides an overview of the research progress of polymeric nanomaterials for modulating autophagy in the treatment of cancers.

Structural insights into the DNA topoisomerase II of the African swine fever virus

Type II topoisomerases are ubiquitous enzymes that play a pivotal role in modulating the topological configuration of double-stranded DNA. These topoisomerases are required for DNA metabolism and have been extensively studied in both prokaryotic and eukaryotic organisms. However, our understanding of virus-encoded type II topoisomerases remains limited. One intriguing example is the African swine fever virus, which stands as the sole mammalian-infecting virus encoding a type II topoisomerase. In this work, we use several approaches including cryo-EM, X-ray crystallography, and biochemical assays to investigate the structure and function of the African swine fever virus type II topoisomerase, pP1192R. We determine the structures of pP1192R in different conformational states and confirm its enzymatic activity in vitro. Collectively, our results illustrate the basic mechanisms of viral type II topoisomerases, increasing our understanding of these enzymes and presenting a potential avenue for intervention strategies to mitigate the impact of the African swine fever virus.

Spermine and spermidine inhibit or induce programmed cell death in Arabidopsis thaliana in vitro and in vivo in a dose-dependent manner.

Polyamines are ubiquitous biomolecules with a number of established functions in eukaryotic cells. In plant cells, polyamines have previously been linked to abiotic and biotic stress tolerance, as well as to the modulation of programmed cell death (PCD), with contrasting reports on their pro-PCD and pro-survival effects. Here, we used two well-established platforms for the study of plant PCD, Arabidopsis thaliana suspension cultures cells and the root hair assay, to examine the roles of the polyamines spermine and spermidine in the regulation of PCD. Using these systems for precise quantification of cell death rates, we demonstrate that both polyamines can trigger PCD when applied exogenously at higher doses, whereas at lower concentrations they inhibit PCD induced by both biotic and abiotic stimuli. Furthermore, we show that concentrations of polyamines resulting in inhibition of PCD generated a transient ROS burst in our experimental system, and activated the expression of oxidative stress- and pathogen response-associated genes. Finally, we examined PCD responses in existing Arabidopsis polyamine synthesis mutants, and identified a subtle PCD phenotype in Arabidopsis seedlings deficient in thermo-spermine. The presented data show that polyamines can have a role in PCD regulation; however, that role is dose-dependent and consequently they may act as either inhibitors, or inducers, of PCD in Arabidopsis.