Scopolamine mitigates oophorectomy-induced osteoporosis: potential mechanisms and direct effects on bone structure.

The aim of our research is to investigate the therapeutic effects of scopolamine (SCO) on osteoporosis and to explore the underlying mechanism. To study osteoporosis, we established an ovariectomy (OVX) model. The rats were divided into four groups: sham operation, OVX, OVX+SCO, and OVX+SCO+ML385 (Nrf2 inhibitor). ELISA, Realtime PCR, Western blot, and kits were utilised to assess the expression of related proteins and substances. The OVX rats exhibited significant weight gain, reduced bone volume, destruction of trabecular and cortical bone microstructure, decreased expression of ALP, OCN, OPN, COL1A1, Runx2, Nrf2 proteins, and CAT, SOD, GST, GPX levels while increased expression of TRAP protein and ROS levels. SCO was able to restore these indices in OVX rats, while ML385 blocked the effects of SCO. In conclusion, SCO inhibits oxidative stress response to exert therapeutic effects on osteoporosis by activating the Nrf2 signalling pathway.

Identification of the organic peroxide scavenging system of Yersinia pseudotuberculosis and its regulation by OxyR.

Oxidative stress caused by reactive oxygen species (ROS) is inevitable for all aerobic microorganisms as ROS are the byproducts of aerobic respiration. For gut pathogens, ROS are an integrated part of colonization resistance which protects the host against bacteria invasion. Alkyl hydroperoxide reductase (AhpR) and organic hydroperoxide resistance (Ohr) proteins are considered as the main enzymes responsible for the degradation of organic peroxides (OPs) in most bacteria. To elucidate how enteric pathogen Yersinia pseudotuberculosis YPIII deals with oxidative stress induced by OPs, we performed transcriptomic analysis and identified the OP scavenging system, which is composed of glutathione peroxidase (Gpx), thiol peroxidase (Tpx), and AhpR. Gpx serves as the main scavenger of OPs, and Tpx assists in the degradation of OPs. Transcriptional factor OxyR regulates Gpx expression, suggesting that OxyR is the regulator mediating the cellular response to OPs. Although AhpR has little influence on OP degradation, its deletion would greatly impair the scavenging ability of OPs in the absence of gpx or tpx. In addition, we found that catalase KatG and KatE are responsive to OPs but do not participate in the removal of OPs.IMPORTANCEIn bacteria, oxidative stress caused by ROS is a continuously occurring cellular response and requires multiple genes to participate in this process. The elimination of OPs is mainly dependent on AhpR and Ohr protein. Here, we carried out transcriptomic analysis to search for enzymes responsible for the removal of organic peroxides in Yersinia pseudotuberculosis. We found that Gpx was the primary OP scavenger in bacteria, which was positively regulated by the oxidative stress regulator OxyR. The OP scavenging system in Y. pseudotuberculosis was composedof Gpx, Tpx, and AhpR. OxyR is the critical global regulator mediating gene expression involved in OPs and H2O2 stress. These findings suggest that Y. pseudotuberculosis has a unique defense system in response to oxidative stress.

Single-cell and spatial transcriptome assays reveal heterogeneity in gliomas through stress responses and pathway alterations.

Background: Glioma is a highly heterogeneous malignancy of the central nervous system. This heterogeneity is driven by various molecular processes, including neoplastic transformation, cell cycle dysregulation, and angiogenesis. Among these biomolecular events, inflammation and stress pathways in the development and driving factors of glioma heterogeneity have been reported. However, the mechanisms of glioma heterogeneity under stress response remain unclear, especially from a spatial aspect. Methods: This study employed single-cell RNA sequencing (scRNA-seq) and spatial transcriptomics (ST) to explore the impact of oxidative stress response genes in oligodendrocyte precursor cells (OPCs). Our analysis identified distinct pathways activated by oxidative stress in two different types of gliomas: high- and low- grade (HG and LG) gliomas. Results: In HG gliomas, oxidative stress induced a metabolic shift from oxidative phosphorylation to glycolysis, promoting cell survival by preventing apoptosis. This metabolic reprogramming was accompanied by epithelial-to-mesenchymal transition (EMT) and an upregulation of stress response genes. Furthermore, SCENIC (Single-Cell rEgulatory Network Inference and Clustering) analysis revealed that oxidative stress activated the AP1 transcription factor in HG gliomas, thereby enhancing tumor cell survival and proliferation. Conclusion: Our findings provide a novel perspective on the mechanisms of oxidative stress responses across various grades of gliomas. This insight enhances our comprehension of the evolutionary processes and heterogeneity within gliomas, potentially guiding future research and therapeutic strategies.

Structural and systems characterization of phosphorylation on metabolic enzymes identifies sex-specific metabolic reprogramming in obesity.

Coordination of adaptive metabolism through cellular signaling networks and metabolic response is essential for balanced flow of energy and homeostasis. Post-translational modifications such as phosphorylation offer a rapid, efficient, and dynamic mechanism to regulate metabolic networks. Although numerous phosphorylation sites have been identified on metabolic enzymes, much remains unknown about their contribution to enzyme function and systemic metabolism. In this study, we stratify phosphorylation sites on metabolic enzymes based on their location with respect to functional and dimerization domains. Our analysis reveals that the majority of published phosphosites are on oxidoreductases, with particular enrichment of phosphotyrosine (pY) sites in proximity to binding domains for substrates, cofactors, active sites, or dimer interfaces. We identify phosphosites altered in obesity using a high fat diet (HFD) induced obesity model coupled to multiomics, and interrogate the functional impact of pY on hepatic metabolism. HFD induced dysregulation of redox homeostasis and reductive metabolism at the phosphoproteome and metabolome level in a sex-specific manner, which was reversed by supplementing with the antioxidant butylated hydroxyanisole (BHA). Partial least squares regression (PLSR) analysis identified pY sites that predict HFD or BHA induced changes of redox metabolites. We characterize predictive pY sites on glutathione S-transferase pi 1 (GSTP1), isocitrate dehydrogenase 1 (IDH1), and uridine monophosphate synthase (UMPS) using CRISPRi-rescue and stable isotope tracing. Our analysis revealed that sites on GSTP1 and UMPS inhibit enzyme activity while the pY site on IDH1 induces activity to promote reductive carboxylation. Overall, our approach provides insight into the convergence points where cellular signaling fine-tunes metabolism.

The cadDX operon contributes to cadmium resistance, oxidative stress resistance, and virulence in zoonotic streptococci.

Mobile genetic elements (MGEs) enable bacteria to acquire novel genes and traits. However, the functions of cargo genes within MGEs remain poorly understood. The cadmium resistance operon cadDX is present in many gram-positive bacteria. Although cadDX has been reported to be involved in metal detoxification, its regulatory mechanisms and functions in bacterial pathogenesis are poorly understood. This study revealed that cadDX contributes to cadmium resistance, oxidative stress resistance, and virulence in Streptococcus suis, an important zoonotic pathogen in pigs and humans. CadX represses cadD expression by binding to the cadDX promoter. Notably, cadX responds to H2O2 stress through an additional promoter within the cadDX operon, mitigating the harmful effect of excessive cadD expression during oxidative stress. cadDX resides within an 11 K integrative and mobilizable element that can autonomously form circular structures. Moreover, cadDX is found in diverse MGEs, accounting for its widespread distribution across various bacteria, especially among pathogenic streptococci. Transferring cadDX into another zoonotic pathogen, Streptococcus agalactiae, results in similar phenotypes, including resistance to cadmium and oxidative stresses and increased virulence of S. agalactiae in mice. The new functions and regulatory mechanisms of cadDX shed light on the importance of the cadDX system in driving evolutionary adaptations and survival strategies across diverse gram-positive bacteria.

The myokine FGF21 associates with enhanced survival in ALS and mitigates stress-induced cytotoxicity.

Amyotrophic lateral sclerosis (ALS) is an age-related and fatal neurodegenerative disease characterized by progressive muscle weakness. There is marked heterogeneity in clinical presentation, progression, and pathophysiology with only modest treatments to slow disease progression. Molecular markers that provide insight into this heterogeneity are crucial for clinical management and identification of new therapeutic targets. In a prior muscle miRNA sequencing investigation, we identified altered FGF pathways in ALS muscle, leading us to investigate FGF21. We analyzed human ALS muscle biopsy samples and found a large increase in FGF21 expression with localization to atrophic myofibers and surrounding endomysium. A concomitant increase in FGF21 was detected in ALS spinal cords which correlated with muscle levels. FGF21 was increased in the SOD1G93A mouse beginning in presymptomatic stages. In parallel, there was dysregulation of the co-receptor, ß-Klotho. Plasma FGF21 levels were increased and high levels correlated with slower disease progression, prolonged survival, and increased body mass index. In NSC-34 motor neurons and C2C12 muscle cells expressing SOD1G93A or exposed to oxidative stress, ectopic FGF21 mitigated loss of cell viability. In summary, FGF21 is a novel biomarker in ALS that correlates with slower disease progression and exerts trophic effects under conditions of cellular stress.

Microplastics in freshwater food chains: Priority list based on identification of oxidative stress response characteristic.

Exogenous exposure to high concentrations of microplastics (MPs) cause oxidative damage to freshwater food chains (FFCs). Thus, the patterns and mechanisms of oxidative stress responses (OSRs) induced by MPs in FFC organisms were investigated using theoretical simulation methods. Results showed an increasing (reduced) OSR was found in lower trophic levels (higher trophic levels). Besides, polycarbonate (polyvinyl chloride) causes the most (least) significant OSRs in FFC organisms, respectively. The impacts of MP additives were also analyzed using the full factorial experimental design, revealing flame retardants significantly influence oxidative stress variability. A constructive solution of "restriction-control-focus" is proposed for different types of MPs by the coefficient of variation-corrected CRITIC and the nested mean classification method. The mechanism analysis revealed a positive correlation between protein secondary structure orderliness and OSRs. Proteins in organisms that contain a high proportion of hydrophobic non-polar amino acids are more likely to bind to MP and enhance OSRs. This is the first study assessing the OSR patterns and ecological risks of MPs and their additives in FFCs with a proposed priority list, providing theoretical support for risk assessments and management strategies in freshwater environments.

Phytohormone-induced changes in growth, physiology, and biochemistry of Aurantiochytrium sp. for sustainable bioproduction.

The study aimed to assess the effects of nine combinations of phytohormones, salicylic acid (SA), gibberellic acid (GA), and jasmonic acid (JA) on the growth, physiology, and biochemistry of Aurantiochytrium sp. Parameters like optical density (OD), biomass, protein content, hydrogen peroxide (H2O2), malondialdehyde (MDA), catalase activity (CAT), and gene expression (malic enzyme (ME) and acetyl-CoA carboxylase (ACCase)) were assessed at various cultivation stages (24, 48, 72, and 96 h). The research also analyzed fatty acid composition, unsaturated fatty acids (UFA), saturated fatty acids (SFA), and the UFA to SFA ratio (USS) to understand the biochemical changes induced by phytohormones. Results demonstrated that modifying phytohormone concentrations significantly affected the characteristics of the microalgae, particularly in correlation with different growth stages, emphasizing the necessity of precise control of phytohormone levels for optimizing cultivation conditions and enhancing bioactive compound production in Aurantiochytrium sp.

Genetic determinants of increased sodium hypochlorite and ciprofloxacin susceptibility in Pseudomonas aeruginosa PA14 biofilms.

Reactive chlorine species (RCS) like sodium hypochlorite (NaOCl) are potent oxidizing agents and widely used biocides in surface disinfection, water treatment, and biofilm elimination. Moreover, RCS are also produced by the human immune system to kill invading pathogens. However, bacteria have developed mechanisms to survive the damage caused by RCS. Using the comprehensive Pseudomonas aeruginosa PA14 transposon mutant library in a genetic screen, we identified a total of 28 P. aeruginosa PA14 mutants whose biofilms showed increased susceptibility to NaOCl in comparison to PA14 WT biofilms. Of these, ten PA14 mutants with a disrupted apaH, PA0793, acsA, PA1506, PA1547, PA3728, yajC, queA, PA3869, or PA14_32840 gene presented a 4-fold increase in NaOCl susceptibility compared to wild-type biofilms. While none of these mutants showed a defect in biofilm formation or attenuated susceptibility of biofilms toward the oxidant hydrogen peroxide (H2O2), all but PA14_32840 also exhibited a 2-4-fold increase in susceptibility toward the antibiotic ciprofloxacin. Further analyses revealed attenuated levels of intracellular ROS and catalase activity only for the apaH and PA1547 mutant, providing insights into the oxidative stress response in P. aeruginosa biofilms. The findings of this paper highlight the complexity of biofilm resistance and the intricate interplay between different mechanisms to survive oxidative stress. Understanding resistance strategies adopted by biofilms is crucial for developing more effective ways to fight resistant bacteria, ultimately contributing to better management of bacterial growth and resistance in clinical and environmental settings.

Quantitative proteome analysis of LAP1-deficient human fibroblasts: A pilot approach for predicting the signaling pathways deregulated in LAP1-associated diseases.

Lamina-associated polypeptide 1 (LAP1), a ubiquitously expressed nuclear envelope protein, appears to be essential for the maintenance of cell homeostasis. Although rare, mutations in the human LAP1-encoding TOR1AIP1 gene cause severe diseases and can culminate in the premature death of affected individuals. Despite there is increasing evidence of the pathogenicity of TOR1AIP1 mutations, the current knowledge on LAP1's physiological roles in humans is limited; hence, investigation is required to elucidate the critical functions of this protein, which can be achieved by uncovering the molecular consequences of LAP1 depletion, a topic that remains largely unexplored. In this work, the proteome of patient-derived LAP1-deficient fibroblasts carrying a pathological TOR1AIP1 mutation (LAP1 E482A) was quantitatively analyzed to identify global changes in protein abundance levels relatively to control fibroblasts. An in silico functional enrichment analysis of the mass spectrometry-identified differentially expressed proteins was also performed, along with additional in vitro functional assays, to unveil the biological processes that are potentially dysfunctional in LAP1 E482A fibroblasts. Collectively, our findings suggest that LAP1 deficiency may induce significant alterations in various cellular activities, including DNA repair, messenger RNA degradation/translation, proteostasis and glutathione metabolism/antioxidant response. This study sheds light on possible new functions of human LAP1 and could set the basis for subsequent in-depth mechanistic investigations. Moreover, by identifying deregulated signaling pathways in LAP1-deficient cells, our work may offer valuable molecular targets for future disease-modifying therapies for TOR1AIP1-associated nuclear envelopathies.

The long non-coding RNA mir155hg promotes NLRP3-inflammasome activation and oxidative stress response in acute lung injury by targeting miR-450b-5p to regulate HIF-1α.

BACKGROUND: Acute lung injury (ALI) can cause multiple organ dysfunction and a high mortality rate. Inflammatory responses, oxidative stress, and immune damage contribute to their pathogenic mechanisms. We studied the role of the newly discovered lncRNA, Lncmir155hg, in ALI. METHODS: The levels of Lncmir155hg and miR-450b-5p from mice with ALI were detected via polymerase chain reaction analysis (qRT-PCR) and Fluorescence in situ hybridization (FISH). Pathological changes of lung were detected by HE (hematoxylin and eosin) staining, and HIF-1α, NOD-like receptor 3 (NLRP3) and caspase-1 protein changes were detected by immunohistochemistry. MLE-12 cells proliferation was detected by Cell-Counting Kit 8 analysis, and reactive oxygen species (ROS) was detected via flow cytometry. NLRP3, apoptosis-associated speck-like protein (ASC), and caspase-1 were measured via western blotting, and enzyme-linked immunosorbent assays detected the expression of Inflammatory factors. Lncmir155hg, miR-450b-5p, miR-450b-5p, and HIF-1α targets were predicted using LncTar and miRWalk and confirmed in dual-luciferase reporter assays. RESULTS: In mice with ALI and MLE-12 cells induced by lipopolysaccharide (LPS), Lncmir155hg was high-expressed and miR-450b-5p was low-expressed. sh-Lncmir155hg reduced the damage of lung tissue, the production of inflammatory cytokines and oxidative stress reaction induced by LPS，miR-450b-5p reverses the effect of Lncmir155hg in mice. sh-Lncmir155hg decreased the protein levels of HIF-1α, NLRP3 and caspase-1 in LPS-induced lung tissues. sh-Lncmir155hg + miR-450b-5p inhibitor transfection reversed the effect of sh-Lncmir155hg on the expression of HIF-1α, NLRP3 and caspase-1. Lncmir155hg knockdown induced proliferation and inhibited NLRP3-inflammasome activation and oxidative stress in MLE-12 cells of ALI. miR-450b-5p was identified to have binding with Lncmir155hg, and inhibition of miR-450b-5p eliminated the effect of si-Lncmir155hg in MLE-12 cells of ALI. More importantly, miR-450b-5p was directly combined with HIF-1α, miR-450b-5p mimic promoted proliferation and inhibited activation of inflammasome associated proteins and reaction of oxidative stress, and HIF-1α overexpression abolished these effects. CONCLUSION: Lncmir155hg aggravated ALI via the miR-450b-5p/HIF-1α axis.

Mesenchymal stem cells-extracellular vesicles alleviate pulmonary fibrosis by regulating immunomodulators.

BACKGROUND: Pulmonary fibrosis (PF) is a chronic interstitial lung disease characterized by fibroblast proliferation and extracellular matrix formation, causing structural damage and lung failure. Stem cell therapy and mesenchymal stem cells-extracellular vesicles (MSC-EVs) offer new hope for PF treatment. AIM: To investigate the therapeutic potential of MSC-EVs in alleviating fibrosis, oxidative stress, and immune inflammation in A549 cells and bleomycin (BLM)-induced mouse model. METHODS: The effect of MSC-EVs on A549 cells was assessed by fibrosis markers [collagen I and α-smooth muscle actin (α-SMA), oxidative stress regulators [nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1), and inflammatory regulators [nuclear factor-kappaB (NF-κB) p65, interleukin (IL)-1ß, and IL-2]. Similarly, they were assessed in the lungs of mice where PF was induced by BLM after MSC-EV transfection. MSC-EVs ion PF mice were detected by pathological staining and western blot. Single-cell RNA sequencing was performed to investigate the effects of the MSC-EVs on gene expression profiles of macrophages after modeling in mice. RESULTS: Transforming growth factor (TGF)-ß1 enhanced fibrosis in A549 cells, significantly increasing collagen I and α-SMA levels. Notably, treatment with MSC-EVs demonstrated a remarkable alleviation of these effects. Similarly, the expression of oxidative stress regulators, such as Nrf2 and HO-1, along with inflammatory regulators, including NF-κB p65 and IL-1ß, were mitigated by MSC-EV treatment. Furthermore, in a parallel manner, MSC-EVs exhibited a downregulatory impact on collagen deposition, oxidative stress injuries, and inflammatory-related cytokines in the lungs of mice with PF. Additionally, the mRNA sequencing results suggested that BLM may induce PF in mice by upregulating pulmonary collagen fiber deposition and triggering an immune inflammatory response. The findings collectively highlight the potential therapeutic efficacy of MSC-EVs in ameliorating fibrotic processes, oxidative stress, and inflammatory responses associated with PF. CONCLUSION: MSC-EVs could ameliorate fibrosis in vitro and in vivo by downregulating collagen deposition, oxidative stress, and immune-inflammatory responses.

Functional Characterization of the Histone Acetyltransferase FcElp3 in Lotus Rhizome Rot-Causing Fungus Fusarium commune.

Fusarium commune is the main pathogen of lotus rhizome rot, which causes the wilt of many plants. Histone acetyltransferase plays a critical part in the growth and virulence of fungi. In the present study, we identified an FcElp3 in F. commune homologous to histone acetyltransferase Elp3. We further constructed a mutant strain of F. commune to determine the function of FcElp3 in fungal growth and pathogenicity. The results showed that the deletion of FcElp3 resulted in reduced mycelial growth and sporulation. Compared with the wild type, the ΔFcElp3 strain showed more tolerance to osmotic stress and cell wall stress responses but was highly sensitive to oxidative stress. The subcellular localization results indicated that FcElp3 was distributed in both the cytoplasm and nucleus. Western blotting showed that FcElp3 was important for acetylation of H3K14 and H4K8. RNA sequencing analysis showed significant transcriptional changes in the ΔFcElp3 mutant, with 3,098 genes upregulated and 5,770 genes downregulated. Peroxisome was the most significantly enriched metabolic pathway for downregulated genes. This led to a significant decrease in the expression of the core transcription factor Fcap1 involved in the oxidative stress response. Pathogenicity tests revealed that the ΔFcElp3 mutant's pathogenicity on lotus was significantly decreased. Together, these findings clearly demonstrated that FcElp3 was involved in fungal growth, development, stress response, and pathogenicity via the direct regulation of multiple target genes.

A sbiT-sbiRS-gloIo regulatory circuit is involved in oxidative stress tolerance of Stenotrophomonas maltophilia.

The sbiT-sbiR-sbiS operon of Stenotrophomonas maltophilia encodes an inner-membrane protein SbiT and a SbiS-SbiR two-component regulatory system. A sbiT mutant displayed a growth defect in LB agar. Mechanism studies revealed that sbiT deletion resulted in SbiSR activation and gloIo upregulation, which increased intracellular ROS level and caused growth defect.

Antioxidant Systems of Plant Pathogenic Fungi: Functions in Oxidative Stress Response and Their Regulatory Mechanisms.

During the infection process, plant pathogenic fungi encounter plant-derived oxidative stress, and an appropriate response to this stress is crucial to their survival and establishment of the disease. Plant pathogenic fungi have evolved several mechanisms to eliminate oxidants from the external environment and maintain cellular redox homeostasis. When oxidative stress is perceived, various signaling transduction pathways are triggered and activate the downstream genes responsible for the oxidative stress response. Despite extensive research on antioxidant systems and their regulatory mechanisms in plant pathogenic fungi, the specific functions of individual antioxidants and their impacts on pathogenicity have not recently been systematically summarized. Therefore, our objective is to consolidate previous research on the antioxidant systems of plant pathogenic fungi. In this review, we explore the plant immune responses during fungal infection, with a focus on the generation and function of reactive oxygen species. Furthermore, we delve into the three antioxidant systems, summarizing their functions and regulatory mechanisms involved in oxidative stress response. This comprehensive review provides an integrated overview of the antioxidant mechanisms within plant pathogenic fungi, revealing how the oxidative stress response contributes to their pathogenicity.

Metabolomics combined with network pharmacology reveals a role for astragaloside IV in inhibiting enterovirus 71 replication via PI3K-AKT signaling.

BACKGROUND: Astragaloside IV (AST-IV), as an effective active ingredient of Astragalus membranaceus (Fisch.) Bunge. It has been found that AST-IV inhibits the replication of dengue virus, hepatitis B virus, adenovirus, and coxsackievirus B3. Enterovirus 71 (EV71) serves as the main pathogen in severe hand-foot-mouth disease (HFMD), but there are no specific drugs available. In this study, we focus on investigating whether AST-IV can inhibit EV71 replication and explore the potential underlying mechanisms. METHODS: The GES-1 or RD cells were infected with EV71, treated with AST-IV, or co-treated with both EV71 and AST-IV. The EV71 structural protein VP1 levels, the viral titers in the supernatant were measured using western blot and 50% tissue culture infective dose (TCID50), respectively. Network pharmacology was used to predict possible pathways and targets for AST-IV to inhibit EV71 replication. Additionally, ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS) was used to investigate the potential targeted metabolites of AST-IV. Associations between metabolites and apparent indicators were performed via Spearman's algorithm. RESULTS: This study illustrated that AST-IV effectively inhibited EV71 replication. Network pharmacology suggested that AST-IV inhibits EV71 replication by targeting PI3K-AKT. Metabolomics results showed that AST-IV achieved these effects by elevating the levels of hypoxanthine, 2-ketobutyric acid, adenine, nicotinic acid mononucleotide, prostaglandin H2, 6-hydroxy-1 H-indole-3- acetamide, oxypurinol, while reducing the levels of PC (14:0/15:0). Furthermore, AST-IV also mitigated EV71-induced oxidative stress by reducing the levels of MDA, ROS, while increasing the activity of T-AOC, CAT, GSH-Px. The inhibition of EV71 replication was also observed when using the ROS inhibitor N-Acetylcysteine (NAC). Additionally, AST-IV exhibited the ability to activate the PI3K-AKT signaling pathway and suppress EV71-induced apoptosis. CONCLUSION: This study suggests that AST-IV may activate the cAMP and the antioxidant stress response by targeting eight key metabolites, including hypoxanthine, 2-ketobutyric acid, adenine, nicotinic acid mononucleotide, prostaglandin H2, 6-Hydroxy-1 H-indole-3-acetamide, oxypurinol and PC (14:0/15:0). This activation can further stimulate the PI3K-AKT signaling to inhibit EV71-induced apoptosis and EV71 replication.

Unravelling the Role of Candida albicans Prn1 in the Oxidative Stress Response through a Proteomics Approach.

Candida albicans Prn1 is a protein with an unknown function similar to mammalian Pirin. It also has orthologues in other pathogenic fungi, but not in Saccharomyces cerevisiae. Prn1 highly increases its abundance in response to H2O2 treatment; thus, to study its involvement in the oxidative stress response, a C. albicans prn1∆ mutant and the corresponding wild-type strain SN250 have been studied. Under H2O2 treatment, Prn1 absence led to a higher level of reactive oxygen species (ROS) and a lower survival rate, with a higher percentage of death by apoptosis, confirming its relevant role in oxidative detoxication. The quantitative differential proteomics studies of both strains in the presence and absence of H2O2 indicated a lower increase in proteins with oxidoreductase activity after the treatment in the prn1∆ strain, as well as an increase in proteasome-activating proteins, corroborated by in vivo measurements of proteasome activity, with respect to the wild type. In addition, remarkable differences in the abundance of some transcription factors were observed between mutant and wild-type strains, e.g., Mnl1 or Nrg1, an Mnl1 antagonist. orf19.4850, a protein orthologue to S. cerevisiae Cub1, has shown its involvement in the response to H2O2 and in proteasome function when Prn1 is highly expressed in the wild type.

Physiological and molecular bases of the nickel toxicity responses in tomato.

Nickel (Ni), a component of urease, is a micronutrient essential for plant growth and development, but excess Ni is toxic to plants. Tomato (Solanum lycopersicum L.) is one of the important vegetables worldwide. Excessive use of fertilizers and pesticides led to Ni contamination in agricultural soils, thus reducing yield and quality of tomatoes. However, the molecular regulatory mechanisms of Ni toxicity responses in tomato plants have largely not been elucidated. Here, we investigated the molecular mechanisms underlying the Ni toxicity response in tomato plants by physio-biochemical, transcriptomic and molecular regulatory network analyses. Ni toxicity repressed photosynthesis, induced the formation of brush-like lateral roots and interfered with micronutrient accumulation in tomato seedlings. Ni toxicity also induced reactive oxygen species accumulation and oxidative stress responses in plants. Furthermore, Ni toxicity reduced the phytohormone concentrations, including auxin, cytokinin and gibberellic acid, thereby retarding plant growth. Transcriptome analysis revealed that Ni toxicity altered the expression of genes involved in carbon/nitrogen metabolism pathways. Taken together, these results provide a theoretical basis for identifying key genes that could reduce excess Ni accumulation in tomato plants and are helpful for ensuring food safety and sustainable agricultural development.

Role of PIP39 in oxidative stress response appears conserved in kinetoplastids.

Kinetoplastids, a group of flagellated protists that are often insect intestinal parasites, encounter various sources of oxidative stress. Such stressors include reactive oxygen species, both internally produced within the protist, and induced externally by host immune responses. This investigation focuses on the role of a highly conserved aspartate-based protein phosphatase, PTP-Interacting protein (PIP39) in managing oxidative stress. In addition to its well accepted role in a Trypanosoma brucei life stage transition, there is evidence of PIP39 participation in the T. brucei oxidative stress response. To examine whether this latter PIP39 role may exist more broadly, we aimed to elucidate PIP39's contribution to redox homeostasis in the monoxenous parasite Leptomonas seymouri. Utilizing CRISPR-Cas9-mediated elimination of PIP39 in conjunction with oxidative stress assays, we demonstrate that PIP39 is required for cellular tolerance to oxidative stress in L. seymouri, positing it as a putative regulatory node for adaptive stress responses. We propose that future analysis of L. seymouri PIP39 enzymatic activity, regulation, and potential localization to a specialized organelle termed a glycosome will contribute to a deeper understanding of the molecular mechanisms by which protozoan parasites adapt to oxidative environments. Our study also demonstrates success at using gene editing tools developed for Leishmania for the related L. seymouri.

A network of transcription factors in complex with a regulating cell cycle cyclin orchestrates fungal oxidative stress responses.

BACKGROUND: Response to oxidative stress is universal in almost all organisms and the mitochondrial membrane protein, BbOhmm, negatively affects oxidative stress responses and virulence in the insect fungal pathogen, Beauveria bassiana. Nothing further, however, is known concerning how BbOhmm and this phenomenon is regulated. RESULTS: Three oxidative stress response regulating Zn2Cys6 transcription factors (BbOsrR1, 2, and 3) were identified and verified via chromatin immunoprecipitation (ChIP)-qPCR analysis as binding to the BbOhmm promoter region, with BbOsrR2 showing the strongest binding. Targeted gene knockout of BbOsrR1 or BbOsrR3 led to decreased BbOhmm expression and consequently increased tolerances to free radical generating compounds (H2O2 and menadione), whereas the ΔBbOsrR2 strain showed increased BbOhmm expression with concomitant decreased tolerances to these compounds. RNA and ChIP sequencing analysis revealed that BbOsrR1 directly regulated a wide range of antioxidation and transcription-associated genes, negatively affecting the expression of the BbClp1 cyclin and BbOsrR2. BbClp1 was shown to localize to the cell nucleus and negatively mediate oxidative stress responses. BbOsrR2 and BbOsrR3 were shown to feed into the Fus3-MAPK pathway in addition to regulating antioxidation and detoxification genes. Binding motifs for the three transcription factors were found to partially overlap in the promoter region of BbOhmm and other target genes. Whereas BbOsrR1 appeared to function independently, co-immunoprecipitation revealed complex formation between BbClp1, BbOsrR2, and BbOsrR3, with BbClp1 partially regulating BbOsrR2 phosphorylation. CONCLUSIONS: These findings reveal a regulatory network mediated by BbOsrR1 and the formation of a BbClp1-BbOsrR2-BbOsrR3 complex that orchestrates fungal oxidative stress responses.