Cloning and characterization of the thioredoxin reductase 1 gene in Hyriopsis cumingii and its regulatory mechanism by Nrf2

The thioredoxin system, consisting of thioredoxin reductases and thioredoxin, plays a crucial role in defending against oxidative stress. Despite its importance, limited research has been conducted on this system in bivalves. In this study, we aimed to clone and characterize the thioredoxin reductase 1 gene from Hyriopsis cumingii (HcTrxR1) and to elucidate its interaction with the nuclear factor erythroid 2-related factor 2 (Nrf2) of H. cumingii (HcNrf2) using a combination of gene cloning, bioinformatics, RNA interference (RNAi), activator/inhibitor treatments, and dual-luciferase reporter assays. We successfully cloned the full-length cDNA of HcTrxR1, which consisted of a 1788 bp open reading frame encoding a 595-amino acid protein. Sequence analysis revealed high conservation of HcTrxR1 compared to homologs in other bivalve species. The expression of HcTrxR1 mRNA was detected across various tissues, with the highest levels observed in the gonads and hemolymph. RNAi and activator/inhibitor experiments demonstrated that HcNrf2 positively regulated the expression of HcTrxR1. Dual-luciferase reporter assays identified two antioxidant response elements in the promoter region of HcTrxR1, which were critical for HcNrf2 binding and transcriptional activation. Additionally, a polyclonal antibody against the HcTrxR1 protein was generated and confirmed for specificity. These findings underscore the regulatory role of Nrf2 in the thioredoxin system of bivalves, offering novel insights into the antioxidant mechanisms in H. cumingii. The study provides a molecular framework that may inform environmental monitoring and conservation efforts in aquatic ecosystems.

Selenomethionine Attenuated H2O2-Induced Oxidative Stress and Apoptosis by Nrf2 in Chicken Liver Cells

Earlier studies have shown that selenomethionine (SM) supplements in broiler breeders had higher deposition in eggs, further reduced the mortality of chicken embryos, and exerted a stronger antioxidant ability in offspring than sodium selenite (SS). Since previous studies also confirmed that Se deposition in eggs was positively correlated with maternal supplementation, this study aimed to directly investigate the antioxidant activities and underlying mechanisms of SS and SM on the chicken hepatocellular carcinoma cell line (LMH). The cytotoxicity results showed that the safe concentration of SM was up to 1000 ng/mL, while SS was 100 ng/mL. In Se treatments, both SS and SM significantly elevated mRNA stability and the protein synthesis rate of glutathione peroxidase (GPx) and thioredoxin reductase (TrxR), two Se-containing antioxidant enzymes. Furthermore, SM exerted protective effects in the H2O2-induced oxidant stress model by reducing free radicals (including ROS, MDA, and NO) and elevating the activities of antioxidative enzymes, which performed better than SS. Furthermore, the results showed that cotreatment with SM significantly induced apoptosis induced by H2O2 on elevating the content of Bcl-2 and decreasing caspase-3. Moreover, investigations of the mechanism revealed that SM might exert antioxidant effects on H2O2-induced LMHs by activating the Nrf2 pathway and enhancing the activities of major antioxidant selenoenzymes downstream. These findings provide evidence for the effectiveness of SM on ameliorating H2O2-induced oxidative impairment and suggest SM has the potential to be used in the prevention or adjuvant treatment of oxidative-related impairment in poultry feeds.

Network Pharmacology Deciphers the Action of Bioactive Polypeptide in Attenuating Inflammatory Osteolysis via the Suppression of Oxidative Stress and Restoration of Bone Remodeling Balance

Oxidative stress involves enormously in the development of chronic inflammatory bone disease, wherein the overproduction of reactive oxygen species (ROS) negatively impacts the bone remodeling via promoting osteoclastogenesis and inhibiting osteogenesis. Lacking effective therapies highlights the importance of finding novel treatments. Our previous study screened a novel bioactive peptide D7 and demonstrated it could enhance the cell behaviors and protect bone marrow mesenchymal stem cells (BMSCs). Since BMSCs are progenitor cells of osteoblast (OB), we therefore ask whether D7 could also protect against the progress of inflammatory osteolysis. To validate our hypothesis and elucidate the underlying mechanisms, we first performed network pharmacology-based analysis according to the molecule structure of D7, and then followed by pharmacological evaluation on D7 by in vitro lipopolysaccharide(LPS)-induced models. The result from network pharmacology identified 20 candidate targets of D7 for inflammatory osteolysis intervention. The further analysis of Gene Ontology (GO)/KEGG pathway enrichment suggested the therapeutic effect of D7 may primarily affect osteoclast (OC) differentiation and function during the inflammatory osteolysis. Through validating the real effects of D7 on OC and OB as postulated, results demonstrated suppressive effects of D7 on LPS-stimulated OC differentiation and resorption, via the inhibition on OC marker genes. Contrarily, by improving the expression of OB marker genes, D7 displayed promotive effects on OB differentiation and alleviated LPS-induced osteogenic damage. Further mechanism study revealed that D7 could reduce LPS-induced ROS formation and strengthen antioxidants expressions in both OC and OB precursors, ameliorating LPS-triggered redox imbalance in bone remodeling. Taken together, our findings unveiled therapeutic effects of D7 against LPS-induced inflammatory osteolysis through the suppression of oxidative stress and the restoration of the bone remodeling process, providing a new therapeutic candidate for chronic inflammatory bone diseases.