Excessive copper induces the production of reactive oxygen species, which is mediated by phospholipase D, nicotinamide adenine dinucleotide phosphate oxidase and antioxidant systems

Copper-Based Nanozymes: Potential Therapies for Infectious Wounds

Bacterial infections are a significant obstacle to the healing of acute and chronic wounds, such as diabetic ulcers and burn injuries. Traditional antibiotics are the primary treatment for bacterial infections, but they present issues such as antibiotic resistance, limited efficacy, and potential side effects. This challenge leads to the exploration of nanozymes as alternative therapeutic agents. Nanozymes are nanomaterials with enzyme-like activities. Owing to their low production costs, high stability, scalability, and multifunctionality, nanozymes have emerged as a prominent focus in antimicrobial research. Among various types of nanozymes, metal-based nanozymes offer several benefits, including broad-spectrum antimicrobial activity and robust catalytic properties. Specifically, copper-based nanozymes (CuNZs) have shown considerable potential in promoting wound healing. They exhibit strong antimicrobial effects, reduce inflammation, and enhance tissue regeneration, making them highly advantageous for use in wound care. This review describes the dual functions of CuNZs in combating infection and facilitating wound repair. Recent advancements in the design and synthesis of CuNZs, evaluating their antimicrobial efficacy, healing promotion, and biosafety both in vitro and in vivo on the basis of their core components, are critically important.

Altered copper transport in oxidative stress-dependent brain endothelial barrier dysfunction associated with Alzheimer's disease

Oxidative stress and blood-brain barrier (BBB) disruption due to brain endothelial barrier dysfunction contribute to Alzheimer's Disease (AD), which is characterized by beta-amyloid (Aβ) accumulation in senile plaques. Copper (Cu) is implicated in AD pathology and its levels are tightly controlled by several Cu transport proteins. However, their expression and role in AD, particularly in relation to brain endothelial barrier function remains unclear. In this study, we examined the expression of Cu transport proteins in the brains of AD mouse models as well as their involvement in Aβ42-induced brain endothelial barrier dysfunction. We found that the Cu uptake transporter CTR1 was upregulated, while the Cu exporter ATP7A was downregulated in the hippocampus of AD mouse models and in Aβ42-treated human brain microvascular endothelial cells (hBMECs). In the 5xFAD AD mouse model, Cu levels (assessed by ICP-MS) were elevated in the hippocampus. Moreover, in cultured hBMECs, Aβ42-induced reactive oxygen species (ROS) production, ROS-dependent loss in barrier function (measured by transendothelial electrical resistance), and tyrosine phosphorylation of CDH5 were all inhibited by either a membrane permeable Cu chelator or by knocking down CTR1 expression. These findings suggest that dysregulated expression of Cu transport proteins may lead to intracellular Cu accumulation in the AD brain, and that Aβ42 promotes ROS-dependent brain endothelial barrier dysfunction and CDH5 phosphorylation in a CTR1-Cu-dependent manner. Our study uncovers the critical role of Cu transport proteins in oxidative stress-related loss of BBB integrity in AD.

Effect of arsenic and copper in kidney of mice: Crosstalk between Nrf2/ Keap1 pathway in apoptosis and pyroptosis

Arsenic (As) and copper (Cu) are two common contaminants in the environment. When organisms are exposed to As or/ and Cu in large quantities or for sustained periods, oxidative stress is induced, adversely affecting kidney function. However, the molecular mechanisms involved in As or/ and Cu-induced nephrotoxicity remain elusive. In this experiment, wild-type C57BL/6 and Nrf2-knockout mice (n = 24 each) were exposed to arsenic trioxide and copper chloride alone or in combination. Our research findings indicate that exposure to As or/ and Cu can activate the Nrf2 antioxidant pathway by upregulating the levels of Nrf2, HO-1, CAT, and downregulating the level of Keap1, thereby reducing As or/ and Cu-induced oxidative stress. Meanwhile, exposure induced kidney cell pyroptosis and apoptosis by promoting the expression of NLRP3 inflammasomes and Caspase-3, which peaked in mice co-treated with As and Cu. Subsequently, we investigated its role in As or/ and Cu-induced kidney injury by knocking out Nrf2. Our results show that after knocking out Nrf2, the expression of antioxidant factors CAT and HO-1 significantly decreased. Based on the low antioxidant capacity after Nrf2 knockout, the levels of NLRP3 inflammasome, GSDMD, and Caspase1 were significantly upregulated after exposure to As and Cu, indicating more severe cellular pyroptosis. In addition, the level of Caspase3-mediated apoptosis was also more severe. Taken together, there is crosstalk between Nrf2-mediated antioxidant capacity and apoptosis/ pyroptosis induced by exposure to As or/ and Cu. Depletion of Nrf2 alters its antioxidant capacity, ultimately leading to more severe apoptosis, pyroptosis, and nephrotoxicity.

Effect of Selenium and Iodine on Oxidative Stress in the First Trimester Human Placenta Explants

Imbalanced maternal micronutrient status, poor placentation, and oxidative stress are associated with greater risk of pregnancy complications, which impact mother and offspring health. As selenium, iodine, and copper are essential micronutrients with key roles in antioxidant systems, this study investigated their potential protective effects on placenta against oxidative stress. First trimester human placenta explants were treated with different concentrations of selenium (sodium selenite), iodine (potassium iodide), their combination or copper (copper (II) sulfate). The concentrations represented deficient, physiological, or super physiological levels. Oxidative stress was induced by menadione or antimycin. Placenta explants were collected, fixed, processed, and embedded for laser ablation inductively coupled plasma-mass spectrometry (LA ICP-MS) element imaging or immunohistochemical labelling. LA ICP-MS showed that placenta could uptake selenium and copper from the media. Sodium selenite and potassium iodide reduced DNA damage and apoptosis (p < 0.05). Following oxidative stress induction, a higher concentration of sodium selenite (1.6 µM) was needed to reduce DNA damage and apoptosis while both concentrations of potassium iodide (0.5 and 1 µM) were protective (p < 0.05). A high concentration of copper (40 µM) increased apoptosis and DNA damage but this effect was no longer significant after induction of oxidative stress. Micronutrients supplementation can increase their content within the placenta and an optimal maternal micronutrient level is essential for placenta health.

Arabidopsis GDSL1 overexpression enhances rapeseed Sclerotinia sclerotiorum resistance and the functional identification of its homolog in Brassica napus

Sclerotinia stem rot (SSR) caused by Sclerotinia sclerotiorum is a devastating disease of rapeseed (Brassica napus L.). To date, the genetic mechanisms of rapeseed' interactions with S. sclerotiorum are not fully understood, and molecular-based breeding is still the most effective control strategy for this disease. Here, Arabidopsis thaliana GDSL1 was characterized as an extracellular GDSL lipase gene functioning in Sclerotinia resistance. Loss of AtGDSL1 function resulted in enhanced susceptibility to S. sclerotiorum. Conversely, overexpression of AtGDSL1 in B. napus enhanced resistance, which was associated with increased reactive oxygen species (ROS) and salicylic acid (SA) levels, and reduced jasmonic acid levels. In addition, AtGDSL1 can cause an increase in lipid precursor phosphatidic acid levels, which may lead to the activation of downstream ROS/SA defence-related pathways. However, the rapeseed BnGDSL1 with highest sequence similarity to AtGDSL1 had no effect on SSR resistance. A candidate gene association study revealed that only one AtGDSL1 homolog from rapeseed, BnaC07g35650D (BnGLIP1), significantly contributed to resistance traits in a natural B. napus population, and the resistance function was also confirmed by a transient expression assay in tobacco leaves. Moreover, genomic analyses revealed that BnGLIP1 locus was embedded in a selected region associated with SSR resistance during the breeding process, and its elite allele type belonged to a minor allele in the population. Thus, BnGLIP1 is the functional equivalent of AtGDSL1 and has a broad application in rapeseed S. sclerotiorum-resistance breeding.

Carbon nano dot decorated copper nanowires for SERS-Fluorescence dual-mode imaging/anti-microbial activity and enhanced angiogenic activity

Copper nanoparticles are explored significantly for their antimicrobial activity, especially for antibiotic-resistant strain infections. However, copper has severe toxic responses and mostly it is due to its generation capability of reactive oxygen species (ROS) molecules while interacting with in vitro or in vivo systems. In the current study, wire shaped copper nanostructures were synthesized via microwave irradiation with single step doping of carbon nanodots (CDs). The synthesized material (CuCs) was characterized by UV-Vis spectroscopy, fluorescence spectroscopy, FTIR, TEM, FESEM, XRD, DLS, and XPS. The fluorescence spectroscopy, microscopy and Raman spectroscopy results suggested CuCs to work well as a bi-modal imaging nanoprobe (fluorescence/SERS). The cell culture studies prove significant cytocompatibility and ROS scavenging property of the samples with respect to control. Further, CuCs-gelatin nanocomposite thin films were prepared and implanted into rodent deep wound model. The histological study has showed enhanced angiogenesis in the subcutaneous region. The results were validated by immuno-histochemistry. The ROS scavenging and enhanced angiogenesis were validated via gene expression studies and a HIF-α induced enhanced angiogenesis mechanism was also proposed for better wound healing.

Probing the contractile vacuole as Achilles' heel of the biotrophic grapevine pathogen Plasmopara viticola

The causative agent of Grapevine Downy Mildew, the oomycete Plasmopara viticola, poses a serious threat to viticulture. In the current work, the contractile vacuole of the zoospore is analysed as potential target for novel plant protection strategies. Using a combination of electron microscopy, spinning disc confocal microscopy, and video differential interference contrast microscopy, we have followed the genesis and dynamics of this vacuole required during the search for the stomata, when the non-walled zoospore is exposed to hypotonic conditions. This subcellular description was combined with a pharmacological study, where the functionality of the contractile vacuole was blocked by manipulation of actin, by Na, Cu, and Al ions or by inhibition of the NADPH oxidase. We further observe that RGD peptides (mimicking binding sites for integrins at the extracellular matrix) can inhibit the function of the contractile vacuole as well. Finally, we show that an extract from Chinese liquorice (Glycyrrhiza uralensis) proposed as biocontrol for Downy Mildews can efficiently induce zoospore burst and that this activity depends on the activity of NADPH oxidase. The effect of the extract can be phenocopied by its major compound, glycyrrhizin, suggesting a mode of action for this biologically safe alternative to copper products.

Involvement of phospholipase D-related signal transduction in chemical-induced programmed cell death in tomato cell cultures

Phospholipase D (PLD) and its product phosphatidic acid (PA) are incorporated in a complex metabolic network in which the individual PLD isoforms are suggested to regulate specific developmental and stress responses, including plant programmed cell death (PCD). Despite the accumulating knowledge, the mechanisms through which PLD/PA operate during PCD are still poorly understood. In this work, the role of PLDα1 in PCD and the associated caspase-like proteolysis, ethylene and hydrogen peroxide (H(2)O(2)) synthesis in tomato suspension cells was studied. Wild-type (WT) and PLDα1-silenced cell lines were exposed to the cell death-inducing chemicals camptothecin (CPT), fumonisin B1 (FB1) and CdSO(4). A range of caspase inhibitors effectively suppressed CPT-induced PCD in WT cells, but failed to alleviate cell death in PLDα1-deficient cells. Compared to WT, in CPT-treated PLDα1 mutant cells, reduced cell death and decreased production of H(2)O(2) were observed. Application of ethylene significantly enhanced CPT-induced cell death both in WT and PLDα1 mutants. Treatments with the PA derivative lyso-phosphatidic acid and mastoparan (agonist of PLD/PLC signalling downstream of G proteins) caused severe cell death. Inhibitors, specific to PLD and PLC, remarkably decreased the chemical-induced cell death. Taken together with our previous findings, the results suggest that PLDα1 contributes to caspase-like-dependent cell death possibly communicated through PA, reactive oxygen species and ethylene. The dead cells expressed morphological features of PCD such as protoplast shrinkage and nucleus compaction. The presented findings reveal novel elements of PLD/PA-mediated cell death response and suggest that PLDα1 is an important factor in chemical-induced PCD signal transduction.

Cu2+ triggers reversible aggregation of a disordered His-rich dehydrin MpDhn12 from Musa paradisiaca

Copper is an essential nutrient, but it is toxic in excess. Here, we cloned and characterized a His-rich low molecular weight dehydrin from Musa paradisiaca, MpDhn12. Analysis by circular dichroism (CD) spectra and a thermal stability assay showed that MpDhn12 is an intrinsically disordered protein, and immobilized-metal affinity chromatography (IMAC) analysis revealed that MpDhn12 can bind Cu(2+) both in vitro and in vivo. Interestingly, MpDhn12 aggregated under excess Cu(2+) conditions, and the aggregation was reversible and impaired by histidine modification with diethylpyrocarbonate (DEPC), while the disordered structure of another dehydrin ERD14 (as a control) was not changed. Furthermore, MpDhn12 could complement the copper-sensitive phenotype of yeast mutant Δsod1. These results together suggested that MpDhn12 may take part in buffering copper levels through chelation and formation of aggregates in excess Cu(2+) conditions. To the best of our knowledge, it is the first report that a dehydrin interchanged between disordered and aggregated state triggered by copper.

Resistance to hemi-biotrophic F. graminearum infection is associated with coordinated and ordered expression of diverse defense signaling pathways

Fusarium species cause serious diseases in cereal staple food crops such as wheat and maize. Currently, the mechanisms underlying resistance to Fusarium-caused diseases are still largely unknown. In the present study, we employed a combined proteomic and transcriptomic approach to investigate wheat genes responding to F. graminearum infection that causes Fusarium head blight (FHB). We found a total of 163 genes and 37 proteins that were induced by infection. These genes and proteins were associated with signaling pathways mediated by salicylic acid (SA), jasmonic acid (JA), ethylene (ET), calcium ions, phosphatidic acid (PA), as well as with reactive oxygen species (ROS) production and scavenging, antimicrobial compound synthesis, detoxification, and cell wall fortification. We compared the time-course expression profiles between FHB-resistant Wangshuibai plants and susceptible Meh0106 mutant plants of a selected set of genes that are critical to the plants' resistance and defense reactions. A biphasic phenomenon was observed during the first 24 h after inoculation (hai) in the resistant plants. The SA and Ca(2+) signaling pathways were activated within 6 hai followed by the JA mediated defense signaling activated around 12 hai. ET signaling was activated between these two phases. Genes for PA and ROS synthesis were induced during the SA and JA phases, respectively. The delayed activation of the SA defense pathway in the mutant was associated with its susceptibility. After F. graminearum infection, the endogenous contents of SA and JA in Wangshuibai and the mutant changed in a manner similar to the investigated genes corresponding to the individual pathways. A few genes for resistance-related cell modification and phytoalexin production were also identified. This study provided important clues for designing strategies to curb diseases caused by Fusarium.

Exogenously induced expression of ethylene biosynthesis, ethylene perception, phospholipase D, and Rboh-oxidase genes in broccoli seedlings

In higher plants, copper ions, hydrogen peroxide, and cycloheximide have been recognized as very effective inducers of the transcriptional activity of genes encoding the enzymes of the ethylene biosynthesis pathway. In this report, the transcriptional patterns of genes encoding the 1-aminocyclopropane-1-carboxylate synthases (ACSs), 1-aminocyclopropane-1-carboxylate oxidases (ACOs), ETR1, ETR2, and ERS1 ethylene receptors, phospholipase D (PLD)-alpha1, -alpha2, -gamma1, and -delta, and respiratory burst oxidase homologue (Rboh)-NADPH oxidase-D and -F in response to these inducers in Brassica oleracea etiolated seedlings are shown. ACS1, ACO1, ETR2, PLD-gamma1, and RbohD represent genes whose expression was considerably affected by all of the inducers used. The investigations were performed on the seedlings with (i) ethylene insensitivity and (ii) a reduced level of the PLD-derived phosphatidic acid (PA). The general conclusion is that the expression of ACS1, -3, -4, -5, -7, and -11, ACO1, ETR1, ERS1, and ETR2, PLD-gamma 1, and RbohD and F genes is undoubtedly under the reciprocal cross-talk of the ethylene and PA(PLD) signalling routes; both signals affect it in concerted or opposite ways depending on the gene or the type of stimuli. The results of these studies on broccoli seedlings are in agreement with the hypothesis that PA may directly affect the ethylene signal transduction pathway via an inhibitory effect on CTR1 (constitutive triple response 1) activity.

Oxidative metabolism, ROS and NO under oxygen deprivation

Oxygen deprivation, in line with other stress conditions, is accompanied by reactive oxygen (ROS) and nitrogen species (RNS) formation and is characterised by a set of metabolic changes collectively named as the 'oxidative stress response'. The controversial induction of oxidative metabolism under the lack of oxygen is necessitated by ROS and RNS signaling in the induction of adaptive responses, and inevitably results in oxidative damage. To prevent detrimental effects of oxidative stress, the levels of ROS and NO are tightly controlled on transcriptional, translational and metabolic levels. Hypoxia triggers the induction of genes responsible for ROS and NO handling and utilization (respiratory burst oxidase, non-symbiotic hemoglobins, several cytochromes P450, mitochondrial dehydrogenases, and antioxidant-related transcripts). The level of oxygen in the tissue is also under metabolic control via multiple mechanisms: Regulation of glycolytic and fermentation pathways to manage pyruvate availability for respiration, and adjustment of mitochondrial electron flow through NO and ROS balance. Both adaptive strategies are controlled by energy status and aim to decrease the respiratory capacity and to postpone complete anoxia. Besides local oxygen concentration, ROS and RNS formation is controlled by an array of antioxidants. Hypoxic treatment leads to the upregulation of multiple transcripts associated with ascorbate, glutathione and thioredoxin metabolism. The production of ROS and NO is an integral part of the response to oxygen deprivation which encompasses several levels of metabolic regulation to sustain redox signaling and to prevent oxidative damage.