Proteome of Saccharomyces cerevisiae under paraquat stress regulated by therapeutic concentration of copper ions

Glycyl-l-histidyl-l-lysine prevents copper- and zinc-induced protein aggregation and central nervous system cell death in vitro

Common features of neurodegenerative diseases are oxidative and inflammatory imbalances as well as the misfolding of proteins. An excess of free metal ions can be pathological and contribute to cell death, but only copper and zinc strongly promote protein aggregation. Herein we demonstrate that the endogenous copper-binding tripeptide glycyl-l-histidyl-l-lysine (GHK) has the ability to bind to and reduce copper redox activity and to prevent copper- and zinc-induced cell death in vitro. In addition, GHK prevents copper- and zinc-induced bovine serum albumin aggregation and reverses aggregation through resolubilizing the protein. We further demonstrate the enhanced toxicity of copper during inflammation and the ability of GHK to attenuate this toxicity. Finally, we investigated the effects of copper on enhancing paraquat toxicity and report a protective effect of GHK. We therefore conclude that GHK has potential as a cytoprotective compound with regard to copper and zinc toxicity, with positive effects on protein solubility and aggregation that warrant further investigation in the treatment of neurodegenerative diseases.

Molecular mechanism of paraquat-induced ferroptosis leading to pulmonary fibrosis mediated by Keap1/Nrf2 signaling pathway

Paraquat (PQ) is a widely used and highly toxic pesticide that is often actively ingested and causes pulmonary fibrosis in patients. Ferroptosis is a regulated form of non-apoptotic cell death associated with iron-dependent lipid peroxidation. Previous studies have shown that ferroptosis is involved in the occurrence and development of acute lung injury (ALI). In this study, a model rat with inflammatory response, oxidative stress, lipid peroxidation, and pulmonary fibrosis was successfully established by PQ administration. The occurrence of ferroptosis in PQ model rats was confirmed by TUNEL staining, iron ion detection, and Ferroptosis related biomarkers detection. Western blotting (WB) and real-time PCR (RT-PCR) showed that the expression of Keap1 was significantly up-regulated and the expression of Nrf2 was significantly down-regulated in the lung tissue of PQ rats. Further transcriptomics and proteomics confirmed: (1) Enrichment of molecular processes related to iron ion binding; (2) Keap1 may promote Nrf2 ubiquitination and lead to Nrf2 degradation; (3) There is functional enrichment in ferroptosis related pathways. Our results suggest that PQ can regulate Keap1/Nrf2 signaling pathway, leading to increased lipid peroxidation and abnormal iron uptake, thereby inducing iron death and exacerbating the progression of pulmonary fibrosis. Our study provides new insights into PQ-induced pulmonary fibrosis.

Mitochondrial superoxide dismutase Sod2 suppresses nuclear genome instability during oxidative stress

Oxidative stress can damage DNA and thereby contribute to genome instability. To avoid an imbalance or overaccumulation of reactive oxygen species (ROS), cells are equipped with antioxidant enzymes that scavenge excess ROS. Cells lacking the RecQ-family DNA helicase Sgs1, which contributes to homology-dependent DNA break repair and chromosome stability, are known to accumulate ROS, but the origin and consequences of this oxidative stress phenotype are not fully understood. Here, we show that the sgs1 mutant exhibits elevated mitochondrial superoxide, increased mitochondrial mass, and accumulation of recombinogenic DNA lesions that can be suppressed by antioxidants. Increased mitochondrial mass in the sgs1Δ mutant is accompanied by increased mitochondrial branching, which was also inducible in wildtype cells by replication stress. Superoxide dismutase Sod2 genetically interacts with Sgs1 in the suppression of nuclear chromosomal rearrangements under paraquat (PQ)-induced oxidative stress. PQ-induced chromosome rearrangements in the absence of Sod2 are promoted by Rad51 recombinase and the polymerase subunit Pol32. Finally, the dependence of chromosomal rearrangements on the Rev1/Pol ζ mutasome suggests that under oxidative stress successful DNA synthesis during DNA break repair depends on translesion DNA synthesis.

Tannic Acid Interfacial Modification of Prochloraz Ethyl Cellulose Nanoparticles for Enhancing the Antimicrobial Effect and Biosafety of Fungicides

With the poorly soluble and intrinsically unstable feature, prochloraz (Pro) was confronted with lower bioavailability in the crop defense against fungal erosion. Therefore, it was a challenging project to explore the innovative antifungal compound delivery system for improving bioavailability. The superior adhesive fungicide formulation was supposed to be an efficient pathway to enhance transmembrane permeability and biological activity. According to abundant phenolic hydroxyl groups, tannic acid (TA) was an ideal modified adhesive biomaterial to improve interfacial interactions. The fundamental purpose of this research was focused on the synergistic mechanism of TA-interfacial-modified Pro-ethyl cellulose (EC) nanoparticles for improving bioavailability and biosafety. In the stability test, TA-modified Pro-EC nanoparticles had the capacity to reduce Pro initial release burst, extending a persistent validity and improving anti-photodegradation property. The toxicity index of Pro-EC and Pro-EC-TA was approximately 2.93-fold and 4.96-fold that of Pro technical against Fusarium graminearum (F. graminearum), respectively. Compared with nonmodified EC nanoparticles, TA-modified EC nanoparticles obtained eminent transmembrane permeability and superior adherence ability to F. graminearum, for hydroxyl and carboxyl groups of TA to enhance interaction with target cell membranes. The contents of cellular reactive oxygen species induced by Pro-EC and Pro-EC-TA nanoparticles were about 2.31 times and 3.00 times that of the control check (CK), respectively. Compared to the CK group, the membrane potential and ergosterol values of F. graminearum treated with Pro-EC-TA nanoparticles were drastically reduced by 74.91 and 56.20%, respectively. In the biosafety assay, the maximum half-lethal concentration value of the TA-modified Pro-EC nanoparticles indicated that the acute toxicity of the Pro-EC-TA nanoparticles to adult zebrafish was approximately 8.34-fold reduced compared to that of the Pro technical. These findings demonstrated that the successful interfacial modification of Pro-EC nanoparticles with TA was a highly efficient, environmentally safe, and promising alternative for sustainable agricultural application, thus making the fungicide formulation process more simplified, easier fabrication, and lower cost.

The Mitochondrial Alternative Oxidase in Ustilago maydis Is Not Involved in Response to Oxidative Stress Induced by Paraquat

It has been shown that the alternative oxidase in mitochondria of fungi and plants has important functions in the response against stress conditions, although their role in some organisms is still unknown. This is the case of Ustilago maydis. There is no evidence of the participation of the U. maydis Aox1 in stressful conditions such as desiccation, high or low temperature, and low pH, among others. Therefore, in this work, we studied the role of the U. maydis Aox1 in cells exposed to oxidative stress induced by methyl viologen (paraquat). To gain insights into the role of this enzyme, we took advantage of four strains: the FB2 wild-type, a strain without the alternative oxidase (FB2aox1Δ), other with the Aox1 fused to the Gfp under the control of the original promoter (FB2aox1-Gfp), and one expressing constitutively de Aox1-Gfp (FB2Potef:aox1-Gfp). Cells were incubated for various times in the presence of 1 mM paraquat and growth, replicative capacities, mitochondrial respiratory activity, Aox1 capacity, and the activities of several antioxidant enzymes (catalase, glutathione peroxidase, glutathione reductase, and superoxide dismutase) were assayed. The results show that (1) the response of U. maydis against oxidative stress was the same in the presence or absence of the Aox1; (2) the activities of the antioxidant enzymes remained constant despite the oxidative stress; and (3) there was a decrease in the GSH/GSSG ratio in U. maydis cells incubated with paraquat.

Paraquat is an agonist of STIM1 and increases intracellular calcium levels

Paraquat (PQ) is an efficient herbicide but leads to high mortality with no antidote in mammals. PQ produces reactive oxygen species (ROS), leading to epithelial-mesenchymal transition (EMT) for pulmonary fibrosis in type II alveolar (AT II) cells. Intriguingly, strategies reducing ROS exhibit limited therapeutic effects, indicating other targets existing for PQ toxicity. Herein we report that PQ is also an agonist for STIM1 that increases intracellular calcium levels. Particularly, PQ promotes STIM1 puncta formation and association with TRPC1 or ORAI for extracellular calcium entry and thus intracellular calcium influx. Further studies reveal the importance of P584&Y586 residues in STIM1 for PQ association that facilitates STIM1 binding to TRPC1. Consequently, the STIM1-TRPC1 route facilitates PQ-induced EMT for pulmonary fibrosis as well as cell death. Our results demonstrate that PQ is an agonist of STIM1 that induces extracellular calcium entry, increases intracellular calcium levels, and thus promotes EMT in AT II cells.

Coral and it's symbionts responses to the typical global marine pollutant BaP by 4D-Proteomics approach

The symbiosis of corals, zooxanthellae, and microbes is the foundation of the coral reef ecosystem. In addition to global warming, marine pollutants are another important factor causing the breakdown of coral symbiosis. Benzo(a)pyrene (BaP) is a globally widespread marine environmental pollutant that poses a severe threat to marine ecosystems. However, responses of coral symbionts to global marine pollutant stress remain unclear. In this study, we selected Acropora formosa as the target coral to explore its response to 50 μg L^-1 BaP stress using diaPASEF proteomics and 16s rRNA microbiome analysis. The results showed that: 1) the coral symbionts were sensitive to BaP stress; 2) the photosynthetic system of zooxanthellae was crucial for the balance of symbiotic relationships; 3) the destruction of the photosynthetic system induced a zooxanthellae hypoxic stress response; 4) corals adapted to BaP stress by promoting non-essential protein degradation and changing energy metabolism strategies; 5) symbiotic bacteria showed strong adaptability to BaP. This study not only fills the gap in understanding the response mechanism of coral symbionts under BaP stress, but also provides fundamental data for coral reef protection strategies.