Function modification of SR-PSOX by point mutations of basic amino acids

<p>Abstract</p> <p>Background</p> <p>Atherosclerosis (AS) is a common cardiovascular disease. Transformation of macrophages to form foam cells by internalizing modified low density-lipoprotein (LDL) via scavenger receptor (SR) is a key pathogenic process in the onset of AS. It has been demonstrated that SR-PSOX functions as either a scavenger receptor for uptake of atherogenic lipoproteins and bacteria or a membrane-anchored chemokine for adhesion of macrophages and T-cells to the endothelium. Therefore, SR-PSOX plays an important role in the development of AS. In this study the key basic amino acids in the chemokine domain of SR-PSOX have been identified for its functions.</p> <p>Results</p> <p>A cell model to study the functions of SR-PSOX was successfully established. Based on the cell model, a series of mutants of human SR-PSOX were constructed by replacing the single basic amino acid residue in the non-conservative region of the chemokine domain (arginine 62, arginine 78, histidine 80, arginine 82, histidine 85, lysine 105, lysine 119, histidine 123) with alanine (designated as R62A, R78A, H80A, R82A, H85A, K105A, K119A and H123A, respectively). Functional studies showed that the mutants with H80A, H85A, and K105A significantly increased the activities of oxLDL uptake and bacterial phagocytosis compared with the wild-type SR-PSOX. In addition, we have also found that mutagenesis of either of those amino acids strongly reduced the adhesive activity of SR-PSOX by using a highly non-overlapping set of basic amino acid residues.</p> <p>Conclusion</p> <p>Our study demonstrates that basic amino acid residues in the non-conservative region of the chemokine domain of SR-PSOX are critical for its functions. Mutation of H80, H85, and K105 is responsible for increasing SR-PSOX binding with oxLDL and bacteria. All the basic amino acids in this region are important in the cells adhesion via SR-PSOX. These findings suggest that mutagenesis of the basic amino acids in the chemokine domain of SR-PSOX may contribute to atherogenesis.</p

AKR1C1 overexpression attenuates the inhibitory effect of glycyrrhizic acid on gastric cancer cell proliferation and migration

Purpose: To investigate the involvement of aldo-keto reductase family 1 member C1 (AKR1C1) in glycyrrhizic acid-mediated gastric cancer.Methods: Immunohistochemistry, quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR), and western blot were used to assess AKR1C1 expression in gastric cancer. Cell proliferation was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) and colony formation assay. Apoptosis was evaluated by flow cytometry. Transwell and wound healing assays were performed to investigate cell invasion and migration, respectively.Results: AKR1C1 was significantly upregulated in gastric cancer tissues and cells (p &lt; 0.01). AKR1C1 knockdown suppressed cell proliferation, migration, and invasion of gastric cancer, but promoted cell apoptosis. Glycyrrhizic acid treatment reduced AKR1C1 expression in gastric cancer cells (p &lt; 0.05). AKR1C1 overexpression attenuated the glycyrrhizic acid-induced increase in gastric cancer cell apoptosis as well as the decrease in cell proliferation, migration, and invasion.Conclusion: AKR1C1 contributes to gastric cancer cell proliferation and metastasis and counteracts the suppressive effects of glycyrrhizic acid on gastric cancer cell proliferation and metastasis

Solvent Isotope Effect on Transfer Hydrogenation of H2O with Glycerine under Alkaline Hydrothermal Conditions

Solvent isotope effect was investigated with 1H-, 2H-NMR, LC-MS and Gas-MS analyses on transfer hydrogenation of H2O with glycerine under alkaline hydrothermal conditions. The results from solvent isotope studies showed that (1) the H on the β-C of lactate was almost exchanged by D2O, which suggests that the hydroxyl (-OH) group on the 2-C of glycerine was first transformed into a carbonyl (C=O) group and then was converted back into a -OH group to form lactate; (2) The presence of large amounts of D was found in the produced hydrogen gas, which shows that the water molecules acted as a reactant; and (3) D% in the produced hydrogen gas was far more than 50%, which straightforwardly shows that acetol was formed in the first place as the most probable intermediate by undergoing a dehydration reaction rather than a dehydrogenation reaction

Effect of hydrofracking fluid on colloid transport in the unsaturated zone

Hydraulic fracturing is expanding rapidly in the US to meet increasing energy demand and requires high volumes of hydrofracking fluid to displace natural gas from shale. Accidental spills and deliberate land application of hydrofracking fluids, which return to the surface during hydrofracking, are common causes of environmental contamination. Since the chemistry of hydrofracking fluids favors transport of colloids and mineral particles through rock cracks, it may also facilitate transport of in situ colloids and associated pollutants in unsaturated soils. We investigated this by subsequently injecting deionized water and flowback fluid at increasing flow rates into unsaturated sand columns containing colloids. Colloid retention and mobilization was measured in the column effluent and visualized in situ with bright field microscopy. While &lt;5% of initial colloids were released by flushing with deionized water, 32–36% were released by flushing with flowback fluid in two distinct breakthrough peaks. These peaks resulted from 1) surface tension reduction and steric repulsion and 2) slow kinetic disaggregation of colloid flocs. Increasing the flow rate of the flowback fluid mobilized an additional 36% of colloids, due to the expansion of water filled pore space. This study suggests that hydrofracking fluid may also indirectly contaminate groundwater by remobilizing existing colloidal pollutants

The SapA Protein Is Involved in Resistance to Antimicrobial Peptide PR-39 and Virulence of Actinobacillus pleuropneumoniae

Antimicrobial peptides are essential to the innate immune defense of the mammal against bacterial infection. However, pathogenic bacteria have evolved multiple strategies to resist and evade antimicrobial peptides, which is vital to bacterial survival and colonization in hosts. PR-39 is a linear porcine antimicrobial peptide containing 39 amino acid residues with a high proline content. Resistance to antimicrobial peptide PR-39 has been observed in Actinobacillus pleuropneumoniae. However, little is known about the factors required for this resistance. In the present study, PR-39 exposure increased the expression of the sapA gene in A. pleuropneumoniae. The sapA gene, which encodes a putative peptide transport periplasmic protein, was deleted from this bacterium. The ΔsapA mutant showed increased sensitivity to PR-39 compared to the wild-type MD12 and complemented PΔsapA strains. However, the ΔsapA mutant did not exhibit any alterations in outer membrane integrity. Scanning electron microscopy showed that the ΔsapA mutant displayed morphological defects, as indicated by a deformed and sunken shape after PR-39 treatment. In addition, disruption of the SapA protein led to reduced colonization and attenuated virulence of A. pleuropneumoniae in the BALB/c mouse model. Collectively, these data suggest that SapA acts as one mechanism for A. pleuropneumoniae to counteract PR-39-mediated killing. To the best of our knowledge, this is the first study to show a mechanism underlying antimicrobial peptide resistance in A. pleuropneumoniae

Identification and validation of the diagnostic signature associated with immune microenvironment of acute kidney injury based on ferroptosis-related genes through integrated bioinformatics analysis and machine learning

Background: Acute kidney injury (AKI) is a common and severe disease, which poses a global health burden with high morbidity and mortality. In recent years, ferroptosis has been recognized as being deeply related to Acute kidney injury. Our aim is to develop a diagnostic signature for Acute kidney injury based on ferroptosis-related genes (FRGs) through integrated bioinformatics analysis and machine learning.Methods: Our previously uploaded mouse Acute kidney injury dataset GSE192883 and another dataset, GSE153625, were downloaded to identify commonly expressed differentially expressed genes (coDEGs) through bioinformatic analysis. The FRGs were then overlapped with the coDEGs to identify differentially expressed FRGs (deFRGs). Immune cell infiltration was used to investigate immune cell dysregulation in Acute kidney injury. Functional enrichment analysis and protein-protein interaction network analysis were applied to identify candidate hub genes for Acute kidney injury. Then, receiver operator characteristic curve analysis and machine learning analysis (Lasso) were used to screen for diagnostic markers in two human datasets. Finally, these potential biomarkers were validated by quantitative real-time PCR in an Acute kidney injury model and across multiple datasets.Results: A total of 885 coDEGs and 33 deFRGs were commonly identified as differentially expressed in both GSE192883 and GSE153625 datasets. In cluster 1 of the coDEGs PPI network, we found a group of 20 genes clustered together with deFRGs, resulting in a total of 48 upregulated hub genes being identified. After ROC analysis, we discovered that 25 hub genes had an area under the curve (AUC) greater than 0.7; Lcn2, Plin2, and Atf3 all had AUCs over than this threshold in both human datasets GSE217427 and GSE139061. Through Lasso analysis, four hub genes (Lcn2, Atf3, Pir, and Mcm3) were screened for building a nomogram and evaluating diagnostic value. Finally, the expression of these four genes was validated in Acute kidney injury datasets and laboratory investigations, revealing that they may serve as ideal ferroptosis markers for Acute kidney injury.Conclusion: Four hub genes (Lcn2, Atf3, Pir, and Mcm3) were identified. After verification, the signature’s versatility was confirmed and a nomogram model based on these four genes effectively distinguished Acute kidney injury samples. Our findings provide critical insight into the progression of Acute kidney injury and can guide individualized diagnosis and treatment