Biological Selenite Reduction, Characterization and Bioactivities of Selenium Nanoparticles Biosynthesised by Pediococcus acidilactici DSM20284.

Selenium (Se) is in great demand as a health supplement due to its superior reactivity and excellent bioavailability, despite selenium nanoparticles (SeNPs) having signs of minor toxicity. At present, the efficiency of preparing SeNPs using lactic acid bacteria is unsatisfactory. Therefore, a probiotic bacterial strain that is highly efficient at converting selenite to elemental selenium is needed. In our work, four selenite-reducing bacteria were isolated from soil samples. Strain LAB-Se2, identified as Pediococcus acidilactici DSM20284, had a reduction rate of up to 98% at ambient temperature. This strain could reduce 100 mg L-1 of selenite to elemental Se within 48 h at pH 4.5-6.0, a temperature of 30-40 °C, and a salinity of 1.0-6.5%. The produced SeNPs were purified, freeze-dried, and subsequently systematically characterised using FTIR, DSL, SEM-EDS, and TEM techniques. SEM-EDS analysis proved the presence of selenium as the foremost constituent of SeNPs. The strain was able to form spherical SeNPs, as determined by TEM. In addition, DLS analysis confirmed that SeNPs were negatively charged (-26.9 mV) with an average particle size of 239.6 nm. FTIR analysis of the SeNPs indicated proteins and polysaccharides as capping agents on the SeNPs. The SeNPs synthesised by P. acidilactici showed remarkable antibacterial activity against E. coli, B. subtilis, S. aureus, and K. pneumoniae with inhibition zones of 17.5 mm, 13.4 mm, 27.9 mm, and 16.2 mm, respectively; they also showed varied MIC values in the range of 15-120 µg mL-1. The DPPH, ABTS, and hydroxyl, and superoxide scavenging activities of the SeNPs were 70.3%, 72.8%, 95.2%, and 85.7%, respectively. The SeNPs synthesised by the probiotic Lactococcus lactis have the potential for safe use in biomedical and nutritional applications.

Salt-like transcription factor 4 promotes laryngeal cancer progression through transcriptional activation of ubiquitin-specific protease 21 to stabilize Yin Yang 1.

Laryngeal cancer (LC) is a rare and challenging clinical problem. Our aim was to investigate the mechanism of salt-like transcription factor 4 (SALL4) in LC. LC tissue and paracancerous tissue were collected. Relative mRNA or protein levels were measured by quantitative real-time polymerase chain reaction or Western blot. MTT, wound healing, and transwell assay were performed to evaluate cell proliferation, migration and invasion. The binding relationship between SALL4 and USP21 promoter was verified by dual-luciferase assay and ChIP. Co-IP and glutathione-S-transferase (GST)-pull down were performed to measure the protein interaction between USP21 and YY1. Additionally, YY1 ubiquitination level was analyzed. It was found that SALL4 mRNA and SALL4 protein levels were elevated in LC clinical tissues and various LC cells. Knockdown of SALL4 inhibited epithelial-mesenchymal transition (EMT) of LC cells. USP21 was transcriptionally activated by SALL4. Co-IP and GST-pull down confirmed USP21 interacted with YY1. USP21 protected YY1 from degradation through deubiquitination. Furthermore, overexpression of USP21 reversed the effect of knockdown of SALL4 on YY1 and EMT in LC cells. In general, SALL4 facilitated EMT of LC cells through modulating USP21/YY1 axis.

Integrated eco-physiological, biochemical, and molecular biological analyses of selenium fortification mechanism in alfalfa.

MAIN CONCLUSION: Foliar Se (IV) application at 100 mg/kg can act as a positive bio-stimulator of redox, photosynthesis, and nutrient metabolism in alfalfa via phenotypes, nutritional compositions, biochemistry, combined with transcriptome analysis. Selenium (Se) is an essential element for mammals, and plants are the primary source of dietary Se. However, Se usually has dual (beneficial/toxic) effects on the plant itself. Alfalfa (Medicago sativa L.) is one of the most important forage resources in the world due to its high nutritive value. In this study, we have investigated the effects of sodium selenite (Se (IV)) (0, 100, 200, 300, and 500 mg/kg) on eco-physiological, biochemical, and transcriptional mechanisms in alfalfa. The phenotypic and nutritional composition alterations revealed that lower Se (IV) (100 mg/kg) levels positively affected alfalfa; it enhanced the antioxidant activity, which may contribute to redox homeostasis and chloroplast function. At 100 mg/kg Se (IV) concentration, the H2O2, and malondialdehyde (MDA) contents decreased by 36.72% and 22.62%, respectively, whereas the activity of glutathione peroxidase (GPX) increased by 31.10%. Se supplementation at 100 mg/kg increased the plant pigments contents, the light-harvesting capacity of PSII (Fv/Fm) and PSI (ΔP700max), and the carbon fixation efficiency, which was demonstrated by enhanced photosynthesis (37.6%). Furthermore, alfalfa shifted carbon flux to protein synthesis to improve quality at 100 mg/kg of Se (IV) by upregulating carbohydrate and amino acid metabolic genes. On the contrary, at 500 mg/kg, Se (IV) became toxic. Higher Se (IV) disordered the plant antioxidant system, increasing H2O2 and MDA by 14.2 and 4.3%, respectively. Moreover, photosynthesis was inhibited by 20.2%, and more structural substances, such as lignin, were synthesized. These results strongly suggest that Se (IV) at a concentration of 100 mg/kg act as the positive bio-stimulator of redox metabolism, photosynthesis, and nutrient in alfalfa.

Transcriptome analysis revealed accumulation-assimilation of selenium and physio-biochemical changes in alfalfa (Medicago sativa L.) leaves.

BACKGROUND: Selenium (Se) is an increasing concern for investigators predominantly because of its consumption in the human body mainly from crops. As the fourth largest plant crop globally, alfalfa is one of the most important forages. Alfalfa was fertilized with selenium(IV) (Se(IV)) under field conditions to study the accumulation and assimilation of Se(IV) and to assess the impact of Se fertilization. RESULTS: It was analyzed that the physio-biochemistry, Se species, combined with transcriptome after spraying Se(IV) at different times (0, 12, and 48 h). 9402 and 12 607 differentially expressed genes (DEGs) were identified at 12 h (versus 0 h) and 48 h (versus 12 h). DEG functional enrichments proposed two time-specific biological processes: Se(IV) accumulation was the primary process at 0-12 h, and its assimilation mainly occurred during 12-48 h. This was further proved by the separation of various Se speciation at different times. It showed that Se-supplementation also affected the soluble protein, soluble sugar, pigment contents and antioxidant capacity. Selenium-biofortification could improve the stress resistance of alfalfa by enhancing antioxidant system to scavenge reactive oxygen species (e.g. hydrogen peroxide) and boosting carbohydrate metabolism. CONCLUSION: By integrating physio-biochemistry, Se-related metabolites, and transcriptome under Se(IV) treatment, this study provides data to guide further work on Se-fortification in alfalfa. © 2022 Society of Chemical Industry.

Comparative proteomics analysis of the responses to selenium in selenium-enriched alfalfa (Medicago sativa L.) leaves.

The mass of leaves and the chlorophyll and selenium content of alfalfa can be increased by the foliar spraying of selenite. To better understand the relationship between changes in the expression of specific proteins and the various metabolic and regulatory pathways affected by selenium treatment, labeling with Tandem Mass Tags (TMT) was used as a proteomics technique to compare control leaves with those enriched with Se. A total of 8,411 proteins were identified, the expression levels of 195 of which were significantly modified, 67 significantly up-regulated and 128 significantly down-regulated. Using gene functional classification and metabolic pathway annotation, selenium treatment was found to have a significant impact on metabolic processes. The energy and substances produced by the metabolic processes of a variety of carbohydrates, lipids, and amino acids, and the metabolism of carbon may be responsible for increasing the yield of alfalfa leaves. Administration of selenium substantially influenced Se-responsive proteins, including ABC transporter G family member 36, Probable glutathione S-transferase and cysteine tRNA ligase. Selenium treatment may also enhance photosynthesis and the defense response of cells. Furthermore, protein ubiquitination also played an important role in the selenium response of alfalfa leaves. In summary, a basic analysis of the selenium response pathway in alfalfa leaves at the proteomics level was conducted, which may assist in a more detailed elucidation of selenium enrichment in alfalfa in the future.

Drug Screening in Human PSC-Cardiac Organoids Identifies Pro-proliferative Compounds Acting via the Mevalonate Pathway.

We have previously developed a high-throughput bioengineered human cardiac organoid (hCO) platform, which provides functional contractile tissue with biological properties similar to native heart tissue, including mature, cell-cycle-arrested cardiomyocytes. In this study, we perform functional screening of 105 small molecules with pro-regenerative potential. Our findings reveal surprising discordance between our hCO system and traditional 2D assays. In addition, functional analyses uncovered detrimental effects of many hit compounds. Two pro-proliferative small molecules without detrimental impacts on cardiac function were identified. High-throughput proteomics in hCO revealed synergistic activation of the mevalonate pathway and a cell-cycle network by the pro-proliferative compounds. Cell-cycle reentry in hCO and in vivo required the mevalonate pathway as inhibition of the mevalonate pathway with a statin attenuated pro-proliferative effects. This study highlights the utility of human cardiac organoids for pro-regenerative drug development, including identification of underlying biological mechanisms and minimization of adverse side effects.

Inefficacy of a highly selective T-type calcium channel blocker in preventing atrial fibrillation related remodeling.

BACKGROUND: The T-type Ca(2+) channel (I(CaT)) blocker mibefradil prevents AF-promoting remodeling occurring with atrial tachycardia, an action that has been attributed to I(CaT) inhibition. However, mibefradil has other effects, including ability to inhibit L-type Ca(2+) channels, Na(+) channels and cytochromes. Thus, the relationship between I(CaT) inhibition and remodeling protection in AF is still unknown. OBJECTIVE: To assess the effects of a novel highly selective Cav3 (I(CaT)) blocker, AZ9112, on atrial remodeling induced by 1-week atrial tachypacing (AT-P) in dogs. METHODS: Mongrel dogs were subjected to AT-P at 400 bpm for 7 days, with atrioventricular-node ablation and right-ventricular demand pacing (80 bpm) to control ventricular rate. Four groups of dogs were studied in investigator-blinded fashion: (1) a sham group, instrumented but without tachypacing or drug therapy (n = 5); (2) a placebo group, tachypaced but receiving placebo (n = 6); (3) a positive control tachypacing group receiving mibefradil (n = 6); and (4) a test drug group, subjected to tachypacing during oral treatment with AZ9112 (n = 8). RESULTS: One-week AT-P decreased atrial effective refractory period (ERP) at 6 of 8 sites and diminished rate-dependent atrial ERP abbreviation. Mibefradil eliminated AT-P-induced ERP-abbreviation at 4 of these 6 sites, while AZ9112 failed to affect ERP at any. Neither drug significantly affected AF vulnerability or AF duration. CONCLUSIONS: I(CaT) blockade with the highly selective compound AZ9112 failed to prevent rate-related atrial remodeling. Thus, prevention of atrial electrophysiological remodeling by mibefradil cannot be attributed exclusively to I(CaT) blockade. These results indicate that I(CaT) inhibition is not likely to be a useful approach for AF therapy.

Discovery of N-[[1-[2-(tert-butylcarbamoylamino)ethyl]-4-(hydroxymethyl)-4-piperidyl]methyl]-3,5-dichloro-benzamide as a selective T-type calcium channel (Cav3.2) inhibitor.

The T-type calcium channel inhibitor Mibefradil was reported to protect the heart from atrial remodeling, a key process involved in the development of atrial fibrillation and arrhythmias. Mibefradil is not a selective T-type calcium channel inhibitor and also affects the function of different ion channels. Our aim was to develop a selective T-type calcium channel inhibitor to validate the importance of T-type-related pharmacology in atrial fibrillation. Structural optimisation of a previously disclosed hit series focussed on minimising exposure to the central nervous system and improving pharmacokinetic properties, while maintain adequate potency and selectivity. This resulted in the design of N-[[1-[2-(tert-butylcarbamoylamino)ethyl]-4-(hydroxymethyl)-4-piperidyl]methyl]-3,5-dichloro-benzamide, a novel, selective, peripherally restricted chemical probe to verify the role of T-type calcium channel inhibition on atrial fibrillation protection.