Search Results (1,674)

Reactive oxygen species (ROS) are often seen solely as harmful byproducts of oxidative metabolism, yet evidence reveals their paradoxical roles in both promoting and inhibiting cancer progression. Despite advances, precise context-dependent mechanisms by which ROS modulate oncogenic signaling, therapeutic response, and tumor microenvironment dynamics remain unclear. Specifically, the spatial and temporal aspects of ROS regulation (i.e., the distinct effects of mitochondrial versus cytosolic ROS on the PI3K/Akt and NF-κB pathways, and the differential cellular outcomes driven by acute versus chronic ROS exposure) have been underexplored. Additionally, the specific contributions of ROS-generating enzymes, like NOX isoforms and xanthine oxidase, to tumor microenvironment remodeling and immune modulation remain poorly understood. This review synthesizes current findings with a focus on these critical gaps, offering novel mechanistic insights into the dualistic nature of ROS in cancer biology. By systematically integrating data on ROS source-specific functions and redox-sensitive signaling pathways, the complex interplay between ROS concentration, localization, and persistence is elucidated, revealing how these factors dictate the paradoxical support of tumor progression or induction of cancer cell death. Particular attention is given to antioxidant mechanisms, including NRF2-mediated responses, that may undermine the efficacy of ROS-targeted therapies. Recent breakthroughs in redox biosensors (i.e., redox-sensitive fluorescent proteins, HyPer variants, and peroxiredoxin–FRET constructs) enable precise, real-time ROS imaging across subcellular compartments. Translational advances, including redox-modulating drugs and synthetic lethality strategies targeting glutathione or NADPH dependencies, further highlight actionable vulnerabilities. This refined understanding advances the field by highlighting context-specific vulnerabilities in tumor redox biology and guiding more precise therapeutic strategies. Continued research on redox-regulated signaling and its interplay with inflammation and therapy resistance is essential to unravel ROS dynamics in tumors and develop targeted, context-specific interventions harnessing their dual roles. Full article

Alzheimer’s disease (AD) is increasingly recognized as a multifactorial disorder driven by a combination of disruptions in proteostasis and organelle communication. The 2020 Lancet commission reported that approximately 10 million people worldwide were affected by AD in the mid-20th century. AD is the most prevalent cause of dementia. By early 2030, the global cost of dementia is projected to rise by USD 2 trillion per year, with up to 85% of that cost attributed to daily patient care. Several factors have been implicated in the progression of neurodegeneration, including increased oxidative stress, the accumulation of misfolded proteins, the formation of amyloid plaques and aggregates, the unfolded protein response (UPR), and mitochondrial–endoplasmic reticulum (ER) calcium homeostasis. However, the exact triggers that initiate these pathological processes remain unclear, in part because clinical symptoms often emerge gradually and subtly, complicating early diagnosis. Among the early hallmarks of neurodegeneration, elevated levels of reactive oxygen species (ROS) and the buildup of misfolded proteins are believed to play pivotal roles in disrupting proteostasis, leading to cognitive deficits and neuronal cell death. The accumulation of amyloid-β (Aβ) plaques and tau neurofibrillary tangles is a characteristic feature of AD. These features contribute to chronic neuroinflammation, which is marked by the release of pro-inflammatory cytokines and chemokines that exacerbate oxidative stress. Given these interconnected mechanisms, targeting stress-related signaling pathways, such as oxidative stress (ROS) generated in the mitochondria and ER, ER stress, UPR, and cytosolic chaperones, represents a promising strategy for therapeutic intervention. This review focuses on the relationship between stress chaperone responses and organelle function, particularly the interaction between mitochondria and the ER, in the development of new therapies for AD and related neurodegenerative disorders. Full article

Background: Short-chain fatty acids (SCFAs), microbial metabolites also known as postbiotics, are essential for maintaining gut health. However, their antiproliferative effects on gastric cancer cells and potential interactions with conventional therapies remain underexplored. This study aimed to investigate the effects of three SCFA salts—magnesium acetate (A), sodium propionate (P), and sodium butyrate (B)—individually and in combination (APB), as well as in combination with dexamethasone (Dex), on AGS gastric adenocarcinoma cells. Methods: AGS cells were treated with PB, AP, AB, APB, Dex, and APB+Dex. Cell viability was assessed to determine antiproliferative effects, and the IC₅₀ of APB was calculated. Flow cytometry was used to evaluate apoptosis and necrosis. Reactive oxygen species (ROS) levels were measured to assess oxidative stress. Proteomic analysis via LC-MS was performed to identify differential protein expression and related pathways impacted by the treatments. Results: SCFA salts showed significant antiproliferative effects on AGS cells, with APB exhibiting a combined IC₅₀ of 568.33 μg/mL. The APB+Dex combination demonstrated strong synergy (combination index = 0.76) and significantly enhanced growth inhibition. Both APB and APB+Dex induced substantial apoptosis (p < 0.0001) with minimal necrosis. APB alone significantly increased ROS levels (p < 0.0001), while Dex moderated this effect in the combination group APB+Dex (p < 0.0001). Notably, the APB+Dex treatment synergistically targeted multiple tumour-promoting mechanisms, including the impairment of redox homeostasis through SLC7A11 suppression, and inhibition of the haemostasis, platelet activation network and NF-κB signalling pathway via downregulation of NFKB1 (−1.34), exemplified by increased expression of SERPINE1 (1.99) within the “Response to elevated platelet cytosolic Ca²⁺” pathway. Conclusions: These findings showed a multifaceted anticancer mechanism by APB+Dex that may collectively impair cell proliferation, survival signalling, immune modulation, and tumour microenvironment support in gastric cancer. Full article

Nucleocytoplasmic trafficking is a highly regulated process that allows the cell to control the partitioning of proteins and nucleic acids between the cytosolic and nuclear compartments. The Ebola virus minor matrix protein VP24 (eVP24) hijacks this process by binding to a region on the NPI-1 subfamily of karyopherin alpha (KPNA) nuclear importers. This region overlaps with the activated transcription factor STAT1 binding site on KPNAs, preventing STAT1 nuclear localization and activation of antiviral gene transcription. However, the molecular interactions of eVP24-KPNA5 binding that lead to the nuclear localization of eVP24 remain poorly characterized. Here, we show that trafficking of eVP24 into the nucleus by KPNA5 requires simultaneous binding of cargo. We also describe the conformational dynamics of KPNA5 and interactions with eVP24 and cargo nuclear localization sequences (NLS) using biophysical approaches. Our results reveal that eVP24 binding to KPNA5 does not impact cargo NLS binding to KPNA5, indicating that simultaneous binding of both cellular cargo and eVP24 to KPNA5 is likely required for nuclear trafficking. Together, these results provide a biophysical basis for how Ebola virus VP24 protein gains access to the nucleus during Ebola virus infection. Full article

Class IIa histone deacetylases (HDACs) are pleiotropic regulators of various differentiation pathways and adaptive responses. They form complexes with other co-repressors and can bind to DNA by interacting with selected transcription factors, with members of the Myocyte Enhancer Factor-2 (MEF2) family being the best characterized. A notable feature of class IIa HDACs is the substitution of tyrosine for histidine in the catalytic site, which has occurred over the course of evolution and has a profound effect on the efficiency of catalysis against acetyl-lysine. Another distinctive feature of this family of “pseudoenzymes” is the regulated nucleus–cytoplasm shuttling associated with several non-histone proteins that have been identified as potential substrates, including proteins localized in the cytosol. Within the complexity of class IIa HDACs, several aspects deserve further investigation. In the following, I will discuss some of the recent advances in our knowledge of class IIa HDACs. Full article

Potassium is the most abundant macronutrient in plants, participating in essential physiological processes such as turgor maintenance. A reduction in cell turgor is a hallmark of the ripening process associated with fruit softening. The dynamic of K⁺ fluxes in fleshy fruits is largely unknown; however, the reallocation of K⁺ into the apoplast has been proposed as a contributing factor to the decrease in fruit turgor, contributing to fruit softening. High-affinity K⁺ transporters belonging to the KUP/HT/HAK transporter family have been implicated in this process in some fruits. In this study, a comprehensive genome-wide analysis of the KUP/KT/HAK family of high-affinity K⁺ transporters in strawberry (Fragaria × ananassa Duch.) was conducted, identifying 60 putative transporter genes. The chromosomal distribution of the FaKUP gene family and phylogenetic relationship and structure of predicted proteins were thoroughly examined. Transcriptomic profiling revealed the expression of 19 FaKUP genes within the fruit receptacle, with a predominant downregulation observed during ripening, particularly in FaKUP14, 24 and 47. This pattern suggests their functional relevance in early fruit development and turgor maintenance. Mineral composition analyses confirmed that K⁺ is the most abundant macronutrient in strawberry fruits, exhibiting a slight decrease as ripening progressed. Membrane potential (E_m) and diffusion potentials (E_D) at increasing external K⁺ concentrations were measured by electrophysiology in parenchymal cells of green and white fruits. The results obtained suggest a significant diminution in cytosolic K⁺ levels in white compared to green fruits. Furthermore, the slope of change in E_D at increasing external K⁺ concentration indicated a lower K⁺ permeability of the plasma membrane in white fruits, aligning with transcriptomic data. This study provides critical insights into the regulatory mechanisms of K⁺ transport during strawberry ripening and identifies potential targets for genetic modifications aimed at enhancing fruit firmness and shelf life. Full article

Background: The mammalian mitochondrial genome has long been considered to encode only 13 proteins. However, a recent study identified a nested alternative open reading frame (nAltORF) within the primate mitochondrial cytb gene, which we designate ncytb, that is reportedly translated in the cytosol using the standard genetic code. This discovery challenges conventional understanding and raises questions about the prevalence, conservation, and translational adaptation of such ORFs. Methods: This study conducted a comprehensive bioinformatic analysis of nested ncytb genes in 289 primate and 380 rodent mitochondrial cytb sequences. Results: Nested ncytb genes meeting the criteria (>150 codons, standard genetic code) were identified in only 10.73% of primate and 20.53% of rodent species, suggesting a patchy phylogenetic distribution. While their encoded proteins showed homology to the previously reported protein encoded by the Homo sapiens nested ncytb gene, overall amino acid conservation was low, and characteristic protein domains or signal peptides were generally not predicted. Crucially, the Kozak consensus sequences surrounding the putative start codons of these ncytb genes were exclusively “weak” or “adequate”, with none classified as “strong” or “optimal”. Codon Adaptation Index (CAI) and Relative Codon Deoptimization Index (RCDI) analyses of the nested ncytb genes revealed neither significant adaptation nor deoptimization to the codon usage of nuclear and mitochondrial genes. Furthermore, cosine similarity analysis indicated that ncytb genes exhibit significantly lower codon usage similarity to both nuclear and mitochondrial gene sets compared to their host cytb genes. Conclusions: These findings collectively suggest that while ncytb genes exist in some mammals, their inconsistent presence, weak translational initiation signals, and lack of adaptation to cytosolic codon usage characterize them as dispensable genetic elements rather than core functional genes. Full article

Chikungunya virus (CHIKV), a mosquito-borne alphavirus, has re-emerged, causing widespread outbreaks and a significant clinical burden. Despite advances in virology, the molecular mechanisms governing CHIKV’s interaction with host cells remain poorly understood. In this study, we aimed to identify novel host protein interactors of the CHIKV nonstructural protein 3 (nsP3), a critical component of the viral replication complex, using mass spectrometry-based proteomic profiling in liver-derived Huh7 cells. Co-immunoprecipitation followed by LC-MS/MS identified a wide array of host proteins associated with nsP3, revealing 52 proteins classified as high-confidence (FDR of 1%, and unique peptides > 2) CHIKV-specific interactors. A bioinformatic analysis using STRING and Cytoscape uncovered interaction networks enriched in metabolic processes, RNA processing, translation regulation, cellular detoxification, stress responses, and immune signaling pathways. A subcellular localization analysis showed that many interactors reside in the cytosol, while others localize to the nucleus, nucleolus, and mitochondria. Selected novel host protein interactions were validated through co-immunoprecipitation and immunofluorescence assays. Our findings provide new insights into the host cellular pathways hijacked by CHIKV and highlight potential targets for therapeutic intervention. This is the first report mapping direct nsP3–host protein interactions in Huh7 cells during CHIKV infection. Full article

The NADPH oxidase 2 (NOX2) complex is a critical regulator of immune homeostasis. It is utilized by phagocytic leukocytes including neutrophils, monocytes, and macrophages to generate reactive oxygen species (ROS) that drive microbe clearance and modulate inflammatory responses. Within NOX2, the essential scaffold protein p47phox plays a pivotal role in orchestrating enzyme activation and facilitating the assembly and membrane translocation of cytosolic components of the complex. Tight regulation of p47phox activity is crucial, and its disruption is linked to a number of pathological conditions. Conversely, its hyperactivity contributes to oxidative stress, tissue damage, the progression of cardiovascular diseases, neurodegenerative disorders, inflammatory conditions, metabolic syndromes, and cancer. In this review, we detail the structural and functional roles of p47phox, mechanisms of its regulation, and its multifaceted contributions to disease pathogenesis. We explore the latest advances in p47phox-targeted therapeutic strategies, discuss current challenges in the field, highlight p47phox’s potential as a transformative target in redox biology and propose future directions to unlock its clinical utility. Full article

In acute myeloid leukemia (AML) it is important to elucidate the biological events that lead from remission to relapse, which have a high probability of leading to an adverse disease outcome. The cancer stem cell marker aldehyde dehydrogenase 1 (ALDH1A1) is underexpressed in AML cells when compared to healthy cells, both at the RNA level and at the protein level, and at least in the former, both in the bone marrow and in peripheral blood. Nonetheless, ALDH1A1/ALDH1A2 activity increases in AML cells during disease relapse and is higher in adverse prognosis AML in comparison with favorable prognosis AML. Furthermore, especially in relapsed AML and in unfavorable AML, AML cells rich in ALDH1A1 can contain high levels of reactive oxygen species (ROS), in parallel with high ALDH1A1/2 activity. This metabolic feature is clearly incompatible with normal stem cells. The term “stem-like” therefore is useful to coin malignant cells with a variety of genetic makeups, metabolic programming and biomarkers that converge in the function of survival of clones sufficient to sustain, spread and re-establish neoplastic disease. Therefore, AML “stem-like” cells survive cancer treatment that eradicates other malignant cell clones. This fact differentiates AML “stem-like” cells from normal stem and progenitor cells that function in tissue regeneration as part of a distinct hierarchical order of cell phenotypes. The ODYSSEY clinical trial is a Phase I/II study designed to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of ABD-3001, a novel therapeutic agent, in patients with AML who have relapsed or are refractory to standard treatments. In this context, ABD-3001 is used as an inhibitor of cytosolic ALDH1 enzymes, such as ALDH1A1 and ALDH1A2. Full article

Calprotectin, the most abundant cytosolic protein in neutrophils, is a S100A8/S100A9 heterodimer released during immune activation. It inhibits bacterial growth by binding to essential metal ions and contributes to inflammation and leukocyte migration. This review highlights calprotectin’s potential as a diagnostic marker for bacterial infections and inflammation. Clinical trials demonstrate that calprotectin is at least as effective as C-reactive protein, procalcitonin, and white blood cell counts in predicting bacterial infections. The rapid elevation of calprotectin levels in the early stages of sepsis, pneumonia, brain injury, and transplant complications underscores its diagnostic value. Predictive use of calprotectin may reduce ICU stays, mortality, and costs. However, challenges remain, including assay standardization and bacterial–viral differentiation. Advanced methods, such as the particle-enhanced turbidimetric immunoassay, enable faster and more reliable measurements. While calprotectin shows promise, further standardization and clinical validation are necessary to optimize its diagnostic utility. Full article

Utilizing a multi-biomarker approach, we assessed the potential adverse effects of pollutants on subcellular responses in the digestive gland of the freshwater mussel Unio crassus from a historically contaminated lowland section (KIZ) of the river Mrežnica compared to its less impacted upstream karstic section (REF) and their seasonality (spring vs. autumn). This approach accounted for the diverse modes of action of pollutants by including biomarkers of metal exposure (metallothioneins, MT), general stress (total cytosolic proteins, TP), antioxidative capacity (catalase, CAT; glutathione, GSH; glutathione-S-transferase, GST), oxidative damage (malondialdehyde, MDA), and neurotoxicity (acetylcholinesterase, AChE). Only in spring, MT concentrations were 15% higher at the REF site (4.38 ± 1.06 µg mg proteins⁻¹) compared to the KIZ site (3.69 ± 0.63 µg mg proteins⁻¹), likely related to elevated Cd bioaccumulation due to the karstic substrate. Regardless of the season, mussels from KIZ showed consistently lower TP and GSH, with significantly higher CAT, GST, and MDA levels, indicating elevated stress, activation of antioxidant defenses, and oxidative damage from chronic exposure to pro-oxidant pollutants, including metal(loid)s and organic contaminants (e.g., ibuprofen, nicotine). Compared to the REF site, AChE activity at the KIZ site was higher in late spring and lower in early autumn, indicating seasonal variability in AChE activity at the contamination-impacted location driven by fluctuating exposure to neurotoxicants, such as drugs and insecticides. Overall, biomarker responses indicated that mild historical pollution, reinforced by current low-capacity sources, has an observable impact on mussel health, posing long-term risks to sediment-dwelling aquatic organisms. Full article

Immunotherapy targeting the immune functions of the tumor microenvironment (TME) is beneficial for colorectal cancer; however, the response rate is poor. Ciprofloxacin is a fluoroquinolone-class antibiotic that is used to treat bacterial infections. The purpose of this study is to assess the mechanism of ciprofloxacin that enhances anti-PD1 in colorectal cancer. We found that ciprofloxacin induced cytosolic DNA, including single-stranded and double-stranded DNA, formation in mouse CT26 colorectal adenocarcinoma cells. Molecules in DNA-sensing signaling such as cGAS, STING, and IFNβ mRNA and protein expression were elicited after ciprofloxacin treatment in CT26 cells. STING siRNA abrogated the cGAS-STING pathway activation by ciprofloxacin. In vivo, ciprofloxacin exhibited a synergistic effect with anti-PD1 to suppress tumor growth in a CT26 syngeneic animal model without biological toxicity. The examination of TME revealed that ciprofloxacin, alone and in combination therapy, induced M1 and red pulp macrophage production in the spleen. In tumors, M1 and M2 macrophage levels were increased by ciprofloxacin, and CD8⁺ T cell granzyme B expression was increased after combination therapy. STING showed the highest expression in tumor specimens after combination treatment. Ciprofloxacin may enhance the anti-PD1 efficacy and modulate the TME through the cGAS-STING pathway. Full article

In addition to the male genome, the fertilizing spermatozoon delivers to the oocyte several factors whose deficiency can cause embryo dysfunction. Sperm oocyte-activating factor, identified as phoshoplipase C zeta (PLCζ), drives oocyte exit from meiotic arrest through a signaling pathway initiated by periodic rises of free cytosolic Ca²⁺ concentration (calcium oscillations). Sperm centrioles, together with oocyte proteins, form centrosomes that are responsible for aster formation, pronuclear migration, and DNA polarization before nuclear syngamy and subsequent mitotic divisions. Sperm DNA fragmentation can be at the origin of aneuploidies, while epigenetic issues, mainly abnormal methylation of DNA-associated histones, cause asynchronies of zygotic gene activation among embryonic cells. Sperm long and short non-coding RNAs are important epigenetic regulators affecting critical developmental processes. Dysfunction of sperm PLCζ, centrioles, DNA, and RNA mostly converge to aneuploidy, developmental arrest, implantation failure, miscarriage, abortion, or offspring disease. With the exception of DNA fragmentation, the other sperm issues are more difficult to diagnose. Specific tests, including heterologous human intracytoplasmic sperm injection (ICSI) into animal oocytes, genetic testing for mutations in PLCZ1 (the gene coding for PLCζ in humans) and associated genes, and next-generation sequencing of sperm transcriptome, are currently available. Oral antioxidant treatment and in vitro selection of healthy spermatozoa can be used in cases of sperm DNA fragmentation, while ICSI with assisted oocyte activation is useful to overcome oocyte-activation defects. No clinically confirmed therapy is yet available for sperm RNA issues. Full article

The family of voltage-dependent anion channels (VDACs) comprises three isoforms (VDAC-1, VDAC-2, VDAC-3). VDACs have been extensively described as localised in the outer mitochondrial membrane where they are involved in the exchange of ions, metabolites, and ATP/ADP between mitochondria and cytosol. The VDAC interacts with disease-specific proteins and thus regulates the mitochondrial function and controls the cellular energy resources, explaining its involvement in cell death and apoptosis. In addition, VDAC-1 and -2 can also be found at other cellular locations such as in the sarcoplasmic reticulum, in the endoplasmic reticulum, as well as in the plasma membrane. Through single-channel pore regulation, oligomerisation, or changed expression levels the VDAC is involved in different neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, Amyotrophic lateral sclerosis, Huntington’s disease, and others. Here, we critically summarise current discussions about the VDAC as a common key player for these diseases. We suggest that the VDAC acts as a transmembrane multifunctional regulatory protein which might serve as a pharmacological target for the development of novel drugs against neurodegenerative diseases such as the application of recombinant antibody technology. Full article