Selenium (Se) biofortification during the growth process of mung bean is an effective method to improve the Se content and quality. However, the effect of Se biofortification on the physicochemical properties of mung bean protein is unclear. The objective of this study was to clarify the changes in the composition, Se forms, particle structure, functional properties, thermal stability, and gel properties of mung bean protein at four Se application levels. The results showed that the Se content of mung bean protein increased in a dose-dependent manner, with 7.96-fold (P1) and 8.52-fold (P2) enhancement at the highest concentration. Exogenous Se application promotes the conversion of inorganic Se to organic Se. Among them, selenomethionine (SeMet) and methyl selenocysteine (MeSeCys) replaced Met and Cys through the S metabolic pathway and became the dominant organic Se forms in Se-enriched mung bean protein, accounting for more than 80 % of the total Se content. Exogenous Se at 30 g/hm2 significantly up-regulated protein content and promoted the synthesis of sulfur-containing protein components and hydrophobic amino acids in the presence of increased levels of SeMet and MeSeCys. Meanwhile, Cys and Met substitution altered the sulfhydryl groups (SH), β-sheets, and β-turns of protein. The particle size and microstructural characteristics depend on the protein itself and were not affected by exogenous Se. The Se-induced increase in the content of hydrophobic amino acids and β-sheets synergistically increases the thermal stability of the protein. Moderate Se application altered the functional properties of mung bean protein, which was mainly reflected in the significant increase in oil holding capacity (OHC) and foaming capacity (FC). In addition, the increase in SH and β-sheets induced by exogenous Se could alter the protein intermolecular network, contributing to the increase in storage modulus (G\') and loss modulus (G″), which resulted in the formation of more highly elastic gels. This study further promotes the application of mung bean protein in the field of food processing and provides a theoretical basis for the extensive development of Se-enriched mung bean protein.

Substitution of disulfide bonds with a diselenide bonds in peptides and proteins is an often-used strategy to increase the stability of naturally occurring peptides and proteins. In this paper, diselenide metathesis between model diselenide dimer peptides, as well as that in diselenide(s)-substituted biologically active peptides, were analyzed. Surprisingly, depending on the tertiary structure of the peptides, we observed that the metathesis reaction occurs under physiological conditions even in the absence of reducing agents, light and heating.

Selenium is an essential trace element in our diet, crucial for the composition of human selenoproteins, which include 25 genes such as glutathione peroxidases and thioredoxin reductases. The regulation of the selenoproteome primarily hinges on the bioavailability of selenium, either from dietary sources or cell culture media. This selenium-dependent control follows a specific hierarchy, with \"housekeeping\" selenoproteins maintaining constant expression while \"stress-regulated\" counterparts respond to selenium level fluctuations. This study investigates the variability in fetal bovine serum (FBS) selenium concentrations among commercial batches and its effects on the expression of specific stress-related cellular selenoproteins. Despite the limitations of our study, which exclusively used HEK293 cells and focused on a subset of selenoproteins, our findings highlight the substantial impact of serum selenium levels on selenoprotein expression, particularly for GPX1 and GPX4. The luciferase reporter assay emerged as a sensitive and precise method for evaluating selenium levels in cell culture environments. While not exhaustive, this analysis provides valuable insights into selenium-mediated selenoprotein regulation, emphasizing the importance of serum composition in cellular responses and offering guidance for researchers in the selenoprotein field.

The trace element selenium (Se) is essential to the physiology of most organisms on the planet. The most well documented of Se\'s biological forms are selenoproteins, where selenocysteine often serves as the catalytic center for crucial redox processes. Se is also found in several other classes of biological molecules, including nucleic acids, sugars, and modified amino acids, although its role in the function of these metabolites is less understood. Despite its prevalence, only a small number of Se-specific biosynthetic pathways have been discovered. Around half of these were first characterized in the past three years, suggesting that the selenometabolome may be more diverse than previously appreciated. Here, we review the recent advances in our understanding of this intriguing biochemical space, and discuss prospects for future discovery efforts.

Selenocysteine (Sec) is encoded by the UGA codon that normally functions as a stop signal and is specifically incorporated into selenoproteins via a unique recoding mechanism. The translational recoding of UGA as Sec is directed by an unusual RNA structure, the SECIS element. Although archaea and eukaryotes adopt similar Sec encoding machinery, the SECIS elements have no similarities to each other with regard to sequence and structure. We analyzed >400 Asgard archaeal genomes to examine the occurrence of both Sec encoding system and selenoproteins in this archaeal superphylum, the closest prokaryotic relatives of eukaryotes. A comprehensive map of Sec utilization trait has been generated, providing the most detailed understanding of the use of this nonstandard amino acid in Asgard archaea so far. By characterizing the selenoproteomes of all organisms, several selenoprotein-rich phyla and species were identified. Most Asgard archaeal selenoprotein genes possess eukaryotic SECIS-like structures with varying degrees of diversity. Moreover, euryarchaeal SECIS elements might originate from Asgard archaeal SECIS elements via lateral gene transfer, indicating a complex and dynamic scenario of the evolution of SECIS element within archaea. Finally, a roadmap for the transition of eukaryotic SECIS elements from archaea was proposed, and selenophosphate synthetase may serve as a potential intermediate for the generation of ancestral eukaryotic SECIS element. Our results offer new insights into a deeper understanding of the evolution of Sec insertion machinery.

Ferroptosis is a novel type of programmed cell death that relies on the build-up of intracellular iron and leads to an increase in toxic lipid peroxides. Glutathione Peroxidase 4 (GPX4) is a crucial regulator of ferroptosis that uses glutathione as a cofactor to detoxify cellular lipid peroxidation. Targeting GPX4 in cancer could be a promising strategy to induce ferroptosis and kill drugresistant cancers effectively. Currently, research on GPX4 inhibitors is of increasing interest in the field of anti-tumor agents. Many reviews have summarized the regulation and ferroptosis induction of GPX4 in human cancer and disease. However, insufficient attention has been paid to GPX4 inhibitors. This article outlines the molecular structures and development prospects of GPX4 inhibitors as novel anticancer agents.

Ferroptosis is a form of regulated cell death induced by iron-dependent accumulation of lipid hydroperoxides. Selenoprotein glutathione peroxidase 4 (GPX4) suppresses ferroptosis by detoxifying lipid hydroperoxides via a catalytic selenocysteine (Sec) residue. Sec, the genetically encoded 21st amino acid, is biosynthesized from a reactive selenium donor on its cognate tRNA[Ser]Sec. It is thought that intracellular selenium must be delivered \'safely\' and \'efficiently\' by a carrier protein owing to its high reactivity and very low concentrations. Here, we identified peroxiredoxin 6 (PRDX6) as a novel selenoprotein synthesis factor. Loss of PRDX6 decreases the expression of selenoproteins and induces ferroptosis via a reduction in GPX4. Mechanistically, PRDX6 increases the efficiency of intracellular selenium utilization by transferring selenium between proteins within the selenocysteyl-tRNA[Ser]Sec synthesis machinery, leading to efficient synthesis of selenocysteyl-tRNA[Ser]Sec. These findings highlight previously unidentified selenium metabolic systems and provide new insights into ferroptosis.

Se-methylselenocysteine (MSC) is recognized for its potential in cancer prevention, yet the specific effects and underlying processes it initiates within non-small cell lung cancer (NSCLC) remain to be fully delineated. Employing a comprehensive array of assays, including CCK-8, colony formation, flow cytometry, MitoSOX Red staining, wound healing, transwell, and TUNEL staining, we evaluated MSC\'s effects on A549 and 95D cell lines. Our investigation extended to the ROS-mediated NF-κB signaling pathway, utilizing Western blot analysis, P65 overexpression, and the application of IκB-α inhibitor (BAY11-7082) or N-acetyl-cysteine (NAC) to elucidate MSC\'s mechanism of action. In vivo studies involving subcutaneous xenografts in mice further confirmed MSC\'s inhibitory effect on tumor growth. Our findings indicated that MSC inhibited the proliferation of A549 and 95D cells, arresting cell cycle G0/G1 phase and reducing migration and invasion, while also inducing apoptosis and increasing intracellular ROS levels. This was accompanied by modulation of key proteins, including the upregulation of p21, p53, E-cadherin, Bax, cleaved caspase-3, cleaved-PARP, and downregulation of CDK4, SOD2, GPX-1. MSC was found to inhibit the NF-κB pathway, as evidenced by decreased levels of P-P65 and P-IκBα. Notably, overexpression of P65 and modulation of ROS levels with NAC could attenuate MSC\'s effects on cellular proliferation and metastasis. Moreover, MSC significantly curtailed tumor growth in vivo and disrupted the NF-κB signaling pathway. In conclusion, our research demonstrates that MSC exhibits anticancer effects against NSCLC by modulating the ROS/NF-κB signaling pathway, suggesting its potential as a therapeutic agent in NSCLC treatment.

UNASSIGNED: Selenium (Se) deficiency, stemming from malnutrition in humans and animals, has the potential to disrupt many vital physiological processes, particularly those reliant on specific selenoproteins. Agronomic biofortification of crops through the application of Se-containing sprays provides an efficient method to enhance the Se content in the harvested biomass. An optimal candidate for systematic enrichment, guaranteeing a broad trophic impact, must meet several criteria: (i) efficient accumulation of Se without compromising crop yield, (ii) effective conversion of mineral Se fertilizer into usable organically bound Se forms (Seorg), (iii) acceptance of a Se-enriched crop as livestock feed, and (iv), interest from the food processing industry in utilization of Se-enriched outputs. Hence, priority should be given to high-protein leafy crops, such as soybean.
UNASSIGNED: A three-year study in the Czech Republic was conducted to investigate the response of field-grown soybean plants to foliar application of Na2SeO4 solutions (0, 15, 40, and 100 g/ha Se); measured outcomes included crop yield, Se distribution in aboveground biomass, and the chemical speciation of Se in seeds.
UNASSIGNED: Seed yield was unaffected by applied SeO4 2-, with Se content reaching levels as high as 16.2 mg/kg. The relationship between SeO4 2-dose and Se content in seeds followed a linear regression model. Notably, the soybeans demonstrated an impressive 73% average recovery of Se in seeds. Selenomethionine was identified as the predominant species of Se in enzymatic hydrolysates of soybean, constituting up to 95% of Seorg in seeds. Minor Se species, such as selenocystine, selenite, and selenate, were also detected. The timing of Se spraying influenced both plant SeO4 2- biotransformation and total content in seeds, emphasizing the critical importance of optimizing the biofortification protocol. Future research should explore the economic viability, long-term ecological sustainability, and the broad nutritional implications of incorporating Se-enriched soybeans into food for humans and animals.

UNASSIGNED: To investigate the feasibility of selenium-methylselenocysteine (SMC) to promote peripheral nerve regeneration and its mechanism of action.
UNASSIGNED: Rat Schwann cells RSC96 cells were randomly divided into 5 groups, which were group A (without any treatment, control group), group B (adding 100 μmol/L H 2O 2), group C (adding 100 μmol/L H 2O 2+100 μmol/L SMC), group D (adding 100 μmol/L H 2O 2+200 μmol/L SMC), group E (adding 100 μmol/L H 2O 2+400 μmol/L SMC); the effect of SMC on cell proliferation was detected by MTT method, and the level of oxidative stress was detected by immunofluorescence for free radicals [reactive oxygen species (ROS)] after determining the appropriate dose group. Thirty-six 4-week-old male Sprague Dawley rats were randomly divided into 3 groups, namely, the sham operation group (Sham group), the sciatic nerve injury group (PNI group), and the SMC treatment group (SMC group), with 12 rats in each group; the rats in the PNI group were fed with food and water normally after modelling operation, and the rats in the SMC group were added 0.75 mg/kg SMC to the drinking water every day. At 4 weeks after operation, the sciatic nerves of rats in each group were sampled for neuroelectrophysiological detection of highest potential of compound muscle action potential (CMAP). The levels of inflammatory factors [interleukin 17 (IL-17), IL-6, IL-10 and oxidative stress factors catalase (CAT), superoxide dismutase (SOD), and malondialdehyde (MDA)] were detected by ELISA assay. The luxol fast blue (LFB) staining was used to observe the myelin density, fluorescence intensity of glial fibrillary acidic protein (GFAP) and myelin basic protein (MBP) was observed by immunofluorescence staining, and myelin morphology was observed by transmission electron microscopy with measurement of axon diameter. Western blot was used to detect the protein expressions of p38 mitogen-activated protein kinases (p38MAPK), phosphorylated p38MAPK (p-p38MAPK), heme oxygenase 1 (HO-1), and nuclear factor erythroid 2-related factor 2 (Nrf2).
UNASSIGNED: MTT assay showed that the addition of SMC significantly promoted the proliferation of RSC96 cells, and the low concentration could achieve an effective effect, so the treatment method of group C was selected for the subsequent experiments; ROS immunofluorescence test showed that group B showed a significant increase in the intensity of ROS fluorescence compared with that of group A, and group C showed a significant decrease in the intensity of ROS fluorescence compared with that of group B ( P<0.05). Neuroelectrophysiological tests showed that the highest potential of CMAP in SMC group was significantly higher than that in PNI and Sham groups ( P<0.05). ELISA assay showed that the levels of IL-6, IL-17, and MDA in PNI group were significantly higher than those in Sham group, and the levels of IL-10, SOD, and CAT were significantly lower; the levels of IL-6, IL-17, and MDA in SMC group were significantly lower than those in PNI group, and the levels of IL-10, SOD, and CAT were significantly higher ( P<0.05). LFB staining and transmission electron microscopy showed that the myelin density and the diameter of axons in the SMC group were significantly higher than those of the PNI group and the Sham group ( P<0.05). Immunofluorescence staining showed that the fluorescence intensity of GFAP and MBP in the SMC group were significantly stronger than those in the PNI group and Sham group ( P<0.05). Western blot showed that the relative expressions of Nrf2 and HO-1 proteins in the SMC group were significantly higher than those in the PNI group and Sham group, and the ratio of p-p38MAPK/p38MAPK proteins was significantly higher in the PNI group than that in the SMC group and Sham group ( P<0.05).
UNASSIGNED: SMC may inhibit oxidative stress and inflammation after nerve injury by up-regulating the Nrf2/HO-1 pathway, and then inhibit the phosphorylation of p38MAPK pathway to promote the proliferation of Schwann cells, which ultimately promotes the formation of myelin sheaths and accelerates the regeneration of peripheral nerves.
UNASSIGNED: 探讨硒-甲基硒代半胱氨酸（selenium-methylselenocysteine，SMC）促进周围神经再生的可行性及其作用机制。.
UNASSIGNED: 将大鼠雪旺细胞RSC96细胞随机分为5组，分别为A组（无任何处理对照组）、B组（加入100 μmol/L H 2O 2）、C组（加入100 μmol/L H 2O 2+100 μmol/L SMC）、D组（加入100 μmol/L H 2O 2+200 μmol/L SMC）、E组（加入100 μmol/L H 2O 2+400 μmol/L SMC）；通过MTT法检测SMC对细胞增殖的影响，确定合适剂量组别后，通过自由基（reactive oxygen species，ROS）免疫荧光检测细胞氧化应激水平。将36只4周龄雄性SD大鼠随机分为3组，分别为假手术组（Sham组）、坐骨神经损伤组（PNI组）及SMC治疗组（SMC组），每组12只；PNI组大鼠造模术后正常喂食、水，SMC组大鼠于每日饮用水中加入0.75 mg/kg SMC。术后4周各组大鼠坐骨神经取材行神经电生理检测复合肌肉动作电位（compound muscle action potential，CMAP）最高电位 ，ELISA法检测炎症因子IL-17、IL-6、IL-10和氧化应激因子过氧化氢酶（catalase，CAT）、超氧化物歧化酶（superoxide dismutase，SOD）、丙二醛（malondialdehyde，MDA）水平，劳克坚劳蓝（luxol fast blue，LFB）染色观测髓鞘密度，免疫荧光染色观察胶质纤维酸性蛋白（glial fibrillary acidic protein，GFAP）和髓鞘碱性蛋白（myelinbasicprotein，MBP）荧光强度，透射电镜观察髓鞘形态并测量轴突直径，Western blot检测p38丝裂原活化蛋白激酶（mitogen-activated protein kinases，MAPK）、磷酸化p38MAPK（phosphorylation p38MAPK，p-p38MAPK）、血红素氧合酶1（heme oxygenase 1，HO-1）、核因子红细胞系2相关因子2（nuclear factor erythroid 2-related factor 2，Nrf2）蛋白相对表达量。.
UNASSIGNED: MTT检测示加入SMC后显著促进RSC96细胞增殖，且低浓度即可达有效效果，故选择C组进入后续实验；ROS免疫荧光检测示B组较A组ROS荧光强度明显上升，C组较B组ROS荧光强度明显下降（ P<0.05）。动物实验神经电生理检测示，SMC组CMAP最高电位显著高于PNI组和Sham组（ P<0.05）。ELISA检测示，PNI组较Sham组IL-6、IL-17、MDA水平明显上升，IL-10、SOD、CAT水平明显下降；SMC组较PNI组IL-6、IL-17、MDA水平明显下降，IL-10、SOD、CAT水平明显上升（ P<0.05）。LFB染色和透射电镜检测示SMC组的髓鞘密度和轴突直径明显优于PNI组和Sham组（ P<0.05）。免疫荧光染色示SMC组GFAP和MBP荧光强度显著强于PNI组和Sham组（ P<0.05）。Western blot检测示SMC组Nrf2、HO-1蛋白相对表达量显著高于PNI组和Sham组，PNI组p-p38MAPK/p38MAPK蛋白表达量比值显著高于SMC组和Sham组（ P<0.05）。.
UNASSIGNED: SMC可能通过上调Nrf2/HO-1通路抑制神经损伤后的氧化应激和炎症反应，进而抑制p38MAPK通路磷酸化促进雪旺细胞增殖，最终促进髓鞘形成和加速周围神经再生。.