Pitfalls and Solutions in Mass Spectrometry-Based Identification of Protein Glycation.

Emerging evidence suggests that advanced glycation end-products (AGEs) such as Nε-(carboxymethyl)lysine (CML) and Nε-(carboxymethyl)lysine (CEL) may play important roles in certain human diseases. Reliable analytical methods are needed for their characterizations and measurements. Pitfalls have been reported for applications of LC-MS/MS to identify various types of post-translational modifications, but not yet for the case of AGEs. Here, we showed that in the absence of manual inspection, cysteine alkylation with 2-iodoacetamide (IAA) can result in false-positive/ambiguous identifications of CML >20%. They were attributed to offsite alkylation together with incorrect monoisotopic peak assignment (pitfall 1) or together with deamidation (pitfall 2). For pitfall 1, false-positive identifications can be alleviated using a peptide mass error tolerance ≤5 ppm during the database search. Pitfall 2 results in ambiguous modification assignments, which may be overcome by using other alkylation reagents. According to calculations of theoretical mass shifts, the use of other common alkylation reagents (iodoacetic acid, 2-chloroacetamide, and acrylamide) should face similar pitfalls. The use of acrylamide can result in false-positive identifications of CEL instead of CML. Subsequently, we showed that compared to IAA, the use of N-isopropylacrylamide (NIPAM) as an alkylation reagent achieved similar levels of proteome coverage, while reducing the offsite alkylation reactions at lysine by more than five times. Furthermore, false-positive/ambiguous identifications of CML due to the two types of pitfalls were absent when using NIPAM. NIPAM alkylation results in a unique mass shift that allows reliable identifications of CML and most likely other AGEs, such as CEL.

Comparison of anther transcriptomes in response to cold stress at the reproductive stage between susceptible and resistant Japonica rice varieties.

BACKGROUND: Rice is one of the most important cereal crops in the world but is susceptible to cold stress (CS). In this study, we carried out parallel transcriptomic analysis at the reproductive stage on the anthers of two Japonica rice varieties with contrasting CS resistance: cold susceptible Longjing11 (LJ11) and cold resistant Longjing25 (LJ25). RESULTS: According to the obtained results, a total of 16,762 differentially expressed genes (DEGs) were identified under CS, including 7,050 and 14,531 DEGs in LJ25 and LJ11, respectively. Examining gene ontology (GO) enrichment identified 35 up- and 39 down-regulated biological process BP GO terms were significantly enriched in the two varieties, with 'response to heat' and 'response to cold' being the most enriched. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis identified 33 significantly enriched pathways. Only the carbon metabolism and amino acid biosynthesis pathways with down-regulated DEGs were enriched considerably in LJ11, while the plant hormone signal transduction pathway (containing 153 DEGs) was dramatically improved. Eight kinds of plant hormones were detected in the pathway, while auxin, abscisic acid (ABA), salicylic acid (SA), and ethylene (ETH) signaling pathways were found to be the top four pathways with the most DEGs. Furthermore, the protein-protein interaction (PPI) network analysis identified ten hub genes (co-expressed gene number ≥ 30), including six ABA-related genes. Various DEGs (such as OsDREB1A, OsICE1, OsMYB2, OsABF1, OsbZIP23, OsCATC, and so on) revealed distinct expression patterns among rice types when the DEGs between LJ11 and LJ25 were compared, indicating that they are likely responsible for CS resistance of rice in cold region. CONCLUSION: Collectively, our findings provide comprehensive insights into complex molecular mechanisms of CS response and can aid in CS resistant molecular breeding of rice in cold regions.

Silk Hydrogel Electrostatically Functionalized with a Polycationic Antimicrobial Peptide: Molecular Interactions, Gel Properties, and Antimicrobial Activity.

Functionalization of silk fibroin hydrogel with antimicrobial activity is essential for promoting the applications of this excellent biomaterial. In this work, a simple approach based on electrostatic interaction is adopted to produce antimicrobial silk hydrogel containing an antimicrobial peptide (AMP), polymyxin B, an important last-line antibiotic to treat multidrug-resistant bacterial superbugs. The polycationic property of this peptide and the negative charge of silk fibroin lead to strong interactions between them, as demonstrated by changes in nanofibril structure, gelation kinetics, ζ-potential, fluorescence emission, and rheological properties of the gel. The hydrogels loaded with polymyxin B demonstrated antimicrobial activity against two Gram-negative bacterial strains. A combination of the results from the different characterizations suggests that the optimal molar ratio of polymyxin B to silk fibroin is 1:2.5. As most AMPs are cationic, this electrostatic approach is suitable for the straightforward functionalization of inert silk hydrogel with other AMPs.

Real-time monitoring the staged interactions between cationic surfactants and a phospholipid bilayer membrane.

The cationic surfactant-lipid interaction directs the development of novel types of nanodrugs or nanocarriers. The membrane action of cationic surfactants also has a wide range of applications. In this work, combining a photo-voltage transient method with the traditional dynamic giant unilamellar vesicle (GUV) leakage assay and molecular dynamics (MD) simulations, we monitored the molecular actions of a representative cationic surfactant, tetradecyl trimethyl ammonium bromide (TTAB), in a wide concentration range (i.e., 0.5 µM-10 mM), on a phospholipid bilayer membrane in real time. With low concentrations (e.g., ≤10 µM), TTAB performed a three-stage acting process, including the structural-disturbance-dominated, adsorption-dominated, and dynamic equilibrium stages. At higher concentrations (e.g., ≥100 µM), this process was accelerated to two stages. Furthermore, TTAB induced deformation and even rupture of the membrane, due to the asymmetric disturbance of surfactant molecules on the two leaflets of a bilayer. All these disturbances induced membrane permeabilization, and the times at which these transitions occurred are given. This work provides information on time and molecular mechanism during the membrane actions of cationic surfactants, and provides a simple and real-time method in studying the dynamic processes at the membrane interface.

Silica nanoparticles cause spermatogenesis dysfunction in mice via inducing cell cycle arrest and apoptosis.

The widespread use of silica nanoparticles (SiNPs) has increased the risk of human exposure, which raised concerns about their adverse effects on human health, especially the reproductive system. Previous studies have shown that SiNPs could cause damage to reproductive organs, but the specific mechanism is still unclear. In this study, to investigate the underlying mechanism of male reproductive toxicity induced by SiNPs, 40 male mice at the age of 8 weeks were divided into two groups and then intraperitoneally injected with vehicle control or 10 mg/kg SiNPs per day for one week. The results showed that SiNPs could damage testicular structure, perturb spermatogenesis and reduce serum testosterone levels, leading to a decrease in sperm quality and quantity. In addition, the ROS level in the testis of exposed mice was significantly increased, followed by imbalance of the oxidative redox status. Further study revealed that exposure to SiNPs led to cell cycle arrest and apoptosis, as shown by downregulation of the expression of positive cell cycle regulators and the activation of TNF-α/TNFR Ⅰ-mediated apoptotic pathway. The results demonstrated that SiNPs could cause testicles injure via inducing oxidative stress and DNA damage which led to cell cycle arrest and apoptosis, and thereby resulting in spermatogenic dysfunction.

Ligand-decoration determines the translational and rotational dynamics of nanoparticles on a lipid bilayer membrane.

Nanoparticles (NPs) promise a huge potential for clinical diagnostic and therapeutic applications. However, nano-bio (e.g., the NP-cell membrane) interactions and underlying mechanisms are still largely elusive. In this study, two types of congeneric peptides, namely PGLa and magainin 2 (MAG2), with similar membrane activities were employed as model ligands for NP decoration, and the diffusion behaviours (including both translation and rotation) of the ligand-decorated NPs on a lipid bilayer membrane were studied via molecular dynamics simulations. It was found that, although both PGLa- and MAG2-coated NPs showed alternatively "hopping" and "jiggling" diffusions, the PGLa-coated ones had an enhanced circling at the hopping stage, while a much confined circling at the jiggling stage. In contrast, the MAG2-coated NPs demonstrated constant circling tendencies throughout the diffusion process. Such differences in the coupling between translational and rotational dynamics of these two types of NPs are ascribed to the different ligand-lipid interactions of PGLa and MAG2, in which the PGLa ligands prefer to vertically insert into the membrane, while MAG2 tends to lie flat on the membrane surface. Our results are helpful for the understanding the underlying associations between the NP motions and their interfacial membrane interactions, and shed light on the possibility of regulating NP behaviours on a cellular surface for better biomedical uses.

Individual Roles of Peptides PGLa and Magainin 2 in Synergistic Membrane Poration.

Synergy between antimicrobial peptides PGLa and Magainin 2 (MAG2) provides an efficient way to enhance their antimicrobial ability. However, the underlying molecular mechanism of such synergy, especially the individual roles of each peptide, remains poorly understood. We combined a giant unilamellar vesicle leakage assay, in situ interfacial photovoltage testing, and molecular dynamics to investigate membrane poration under the action of PGLa, MAG2, or a PGLa/MAG2 mixture. Our results clearly show the different membrane action modes of the three systems and demonstrate the importance of forming PGLa-MAG2 heterodimers in the membrane poration process. PGLa inserted into and extracted from a membrane rapidly and continually with minimal aggregation and produced only transient, small pores. In contrast, MAG2 peptides tended to aggregate together on the membrane surface or only shallowly embed in the membrane. Additionally, the PGLa and MAG2 residues were well integrated into the membrane via the formation of PGLa-MAG2 heterodimers. The membrane defect produced by the rapid insertion of PGLa was stabilized by MAG2, which further recruited other peptides for the formation of PGLa-MAG2 heterodimers and even heterodimer clusters. Growth in pore size then occurred in a step-by-step process involving the formation and assembly of heterodimer clusters within the membrane. Our results provide insight into the complicated synergy that occurs between PGLa and MAG2 during membrane poration and will assist in the design of new antimicrobial peptides.

MiR-130b inhibits proliferation and induces apoptosis of gastric cancer cells via CYLD.

A role of microRNA-130b (miR-130b) in the carcinogenesis of gastric cancer remains undetermined. In this study, we studied the effects and mechanism of miR-130b to the gastric cell proliferation and apoptosis. We found that the levels of miR-130b significantly up-regulated in gastric cancer tissue, compared to the paired adjacent non-tumor gastric tissue. The miR-130b levels in gastric cancer cell lines were significantly higher than those in control normal gastric tissues. Transfection with the miR-130b mimic enhanced the cell proliferation and suppressed cell apoptosis in gastric cancer cells, while transfection with the anti-sense of miR-130b (anti-miR-130b) suppressed cell proliferation and induced cell apoptosis in gastric cancer cells. Bioinformatics analyses showed that cylindromatosis gene (CYLD) was a potential target gene of miR-130b. The luciferase activity assay and western blot verified that miR-130b targeted CYLD messenger RNA (mRNA) to modulate its protein levels. Together, our study suggests that aberrantly expressed miR-130b may regulate cell apoptosis and proliferation of human gastric cancer cells via CYLD, which appears to be a promising therapeutic target for gastric cancer.

[Anti-fibrotic role of AcSDKP through inhibition of P38MAPK pathway activity mediated transforming growth beta receptors in rat with silicosis].

OBJECTIVE: To investigate the distribution and expression of transforming growth factor beta (TGF-ß) receptors I and II, p38 mitogen-activated protein kinase (p38 MAPK), and type I and type III collagen in the lungs of rats with silicosis and cultured pulmonary fibroblasts, and to investigate the relationship of the anti-fibrosis effect of N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP) with its inhibition of TGF-ß receptor-mediated p38 MAPK pathway activity. METHODS: Rats were randomly divided into control group, silicosis model group, and AcSDKP treatment group (n = 10 for each group). For the model group and AcSDKP treatment group, rats were intratracheally instilled with silica to establish a silicosis model. Cultured pulmonary fibroblasts from neonatal rats were divided into control group, TGF-ß1 stimulation group, TGF-ß receptor inhibition group, p38 MAPK pathway inhibition group, and AcSDKP treatment group. The protein expression of TGF-ß receptors I and II, p38 MAPK, and type I and type III collagen were determined by immunohistochemistry and Western blot. The mRNA expression of TGF-ß receptors I and II were determined by real-time PCR. The distribution and nuclear translocation of phospho-p38 MAPK in cultured fibroblasts were determined by laser scanner confocal microscopy. RESULTS: In the AcSDKP treatment group, AcSDKP reduced the expression of TGF-ß receptors I and II, phospho-p38 MAPK, and type I and type III collagen to 86.12%, 41.01%, 42.63%, 89.05%, and 52.71%, respectively, of those of the silicosis model group (P < 0.05). In cultured fibroblasts, AcSDKP reduced the mRNA expression of TGF-ß receptors I and II to 42.26% and 54.33%, respectively, of those of the TGF-ß1 stimulation group; the protein expression of TGF-ß receptors I and II, phospho-p38 MAPK, and type 1 and type III collagen was reduced to 58.14%, 51.40%, 45.6%, 58.04%, and 44.74%, respectively, of those of the TGF-ß1 stimulation group. The phospho-p38 MAPK translocation from plasma to the nucleus was also inhibited; the nucleus/plasma ratio of p38 MAPK and the protein expression of type I and type III collagen were reduced to 68.60%, 58.04%, and 44.74%, respectively, of those of the TGF-ß stimulation group (P < 0.05). CONCLUSION: AcSDKP can inhibit the expression of collagen through inhibition of TGF-ß receptor-mediated p38 MAPK pathway activity, and is thus able to exert anti-fibrosis effect in rats with silicosis.

Enhanced Thermoelectric Performance of PbTe Nanocomposites with Sb Nanoinclusions.

In the present work, the thermoelectric properties of PbTe embedded with spherical Sb nanoscale inclusions were calculated in detail, following the idea that energy-selective carrier scattering can effectively increase the Seebeck coefficient. The quantitative relationships between such nanostructures in PbTe and thermoelectric properties indicated that interface potential barrier induced by Sb nanoinclusions results in a significant enhancement of the Seebeck coefficient, especially when around room temperature. Furthermore, the optimal parameters for boosting the thermoelectric performance of PbTe were found to be 4 nm-radius Sb nanoinclusions with high concentration.

Transgenic early japonica rice: Integration and expression characterization of stem borer resistance Bt gene.

BACKGROUND: Transgenic insect-resistant rice offers an environmentally friendly approach to mitigate yield losses caused by lepidopteran pests, such as stem borers. Bt (Bacillus thuringiensis) genes encode insecticidal proteins and are widely used to confer insect resistance to genetically modified crops. This study investigated the integration, inheritance, and expression characteristics of codon-optimised synthetic Bt genes, cry1C* and cry2A*, in transgenic early japonica rice lines. METHODS: The early japonica rice cultivar, Songgeng 9 (Oryza sativa), was transformed with cry1C* or cry2A*, which are driven by the ubi promoter via Agrobacterium tumefaciens-mediated transformation. Molecular analyses, including quantitative PCR (qPCR), enzyme-linked immunosorbent assay (ELISA), and Southern blot analysis were performed to confirm transgene integration, inheritance, transcriptional levels, and protein expression patterns across different tissues and developmental stages. RESULTS: Stable transgenic early japonica lines exhibiting single-copy transgene integration were established. Transcriptional analysis revealed variations in Bt gene expression among lines, tissues, and growth stages, with higher expression levels observed in leaves than in other organs. Notably, cry2A* exhibited consistently higher mRNA and protein levels than cry1C* across all examined tissues and developmental time points. Bt protein accumulation followed the trend of leaves > stem sheaths > young panicles > brown rice, with peak expression during the filling stage in the vegetative tissues. CONCLUSIONS: Synthetic cry2A* displayed markedly elevated transcription and translation compared to cry1C* in the transgenic early japonica rice lines examined. Distinct spatiotemporal patterns of Bt gene expression were elucidated, providing insights into the potential insect resistance conferred by these genes in rice. These findings will contribute to the development of insect-resistant japonica rice varieties and facilitate the rational deployment of Bt crops.

Comparative Metabolome Profiling for Revealing the Effects of Different Cooking Methods on Glutinous Rice Longjing57 (Oryza sativa L. var. Glutinosa).

Glutinous rice (GR), an important food crop in Asia, provides prolonged energy for the human body due to its high amylopectin content. The non-volatile metabolites generated by different cooking methods that affect the nutritional value and color of GR are still poorly understood. Herein, a widely targeted metabolomics approach was used to understand the effects of different cooking methods (steaming, baking, and frying) on the metabolite profiles of GR. Compared with other treatments, steamed GR had a brighter color and significantly lower contents of total sugar, starch, amylopectin, and amylose, at 40.74%, 14.13%, 9.78%, and 15.18%, respectively. Additionally, 70, 108, and 115 metabolites were significantly altered in the steaming, baking, and frying groups respectively, and amino acid and carbohydrate metabolism were identified as the representative metabolic pathways based on KEGG annotations. Further evaluation of 14 amino acids and 12 carbohydrates in steamed GR, especially 4-aminobutyric acid, suggested its high nutraceutical value. Additionally, multivariate analysis indicated that total sugar content, amylose content, beta-alanine methyl ester hydrochloride, and 4-aminobutyric acid played a critical role in color formation in raw and cooked GR. Finally, the levels of major amino acids and carbohydrates were quantified by conventional methods to verify the reliability of the metabolome. Consequently, this in-depth understanding of metabolite profiling in normal cooking methods has provided a foundation for the processing of GR products.

Pedigree genome data of an early-matured Geng/japonica glutinous rice mega variety Longgeng 57.

By using PacBio HiFi technology, we produced over 700 Gb of long-read sequencing (LRS) raw data; and by using Illumina paired-end whole-genome shotgun (WGS) sequencing technology, we generated more than 70 Gb of short-read sequencing (SRS) data. With LRS data, we assembled one genome and then generate a set of annotation data for an early-matured Geng/japonica glutinous rice mega variety genome, Longgeng 57 (LG57), which carries multiple elite traits including good grain quality and wide adaptability. Together with the SRS data from three parents of LG57, pedigree genome variations were called for three representative types of genes. These data sets can be used for deep variation mining, aid in the discovery of new insights into genome structure, function, and evolution, and help to provide essential support to biological research in general.

Arginine catabolism is essential to polymyxin dependence in Acinetobacter baumannii.

Polymyxins are often the only effective antibiotics against the "Critical" pathogen Acinetobacter baumannii. Worryingly, highly polymyxin-resistant A. baumannii displaying dependence on polymyxins has emerged in the clinic, leading to diagnosis and treatment failures. Here, we report that arginine metabolism is essential for polymyxin-dependent A. baumannii. Specifically, the arginine degradation pathway was significantly altered in polymyxin-dependent strains compared to wild-type strains, with critical metabolites (e.g., L-arginine and L-glutamate) severely depleted and expression of the astABCDE operon significantly increased. Supplementation of arginine increased bacterial metabolic activity and suppressed polymyxin dependence. Deletion of astA, the first gene in the arginine degradation pathway, decreased phosphatidylglycerol and increased phosphatidylethanolamine levels in the outer membrane, thereby reducing the interaction with polymyxins. This study elucidates the molecular mechanism by which arginine metabolism impacts polymyxin dependence in A. baumannii, underscoring its critical role in improving diagnosis and treatment of life-threatening infections caused by "undetectable" polymyxin-dependent A. baumannii.

Genistein attenuates ischemic oxidative damage and behavioral deficits via eNOS/Nrf2/HO-1 signaling.

Global cerebral ischemia, such as occurs following cardiac arrest, can lead to oxidative stress, hippocampal neuronal cell death, and cognitive defects. The current study examined the potential beneficial effect and underlying mechanisms of post-treatment with the naturally occurring isoflavonic phytoestrogen, genistein, which has been implicated to attenuate oxidative stress. Genistein (1 mg kg(-1)) was administered i.v. 5 min after reperfusion in rats subjected to four-vessel global cerebral ischemia (GCI). The results revealed that genistein exerted significant neuroprotection of hippocampal CA1 neurons following GCI, as evidenced by an increase in NeuN-positive neurons and the decrease in TUNEL-positive neurons. Furthermore, genistein treatment also resulted in significantly improved spatial learning and memory as compared to vehicle control animals. The beneficial effects of genistein appear to be mediated by an increase of phosphorylation/activation of eNOS, with subsequent activation of the antioxidant/detoxification Nrf2/Keap1 transcription system. Along these lines, genistein increased keap1 S-nitrosylation, with a corresponding nuclear accumulation and enhanced DNA binding activity of Nrf2. Genistein also enhanced levels of the Nrf2 downstream antioxidant protein, heme oxygenase (HO)-1, as compared to vehicle control groups. In accordance with its induction of Nrf2 activation, genistein exerted a robust attenuation of oxidative DNA damage and lipid peroxidative damage in hippocampal CA1 neurons after GCI, as measured by immunofluorescence staining of the oxidative stress markers, 8-hydroxy-2-deoxyguanosine (8-OHdG) and 4-Hydroxynonenal (4-HNE). Interestingly, the aforementioned effects of genistein were abolished by pretreatment with L-NAME, an inhibitor of eNOS activation. In conclusion, the results of the study demonstrate that low dose genistein can exert significant antioxidant, neuroprotective, and cognitive-enhancing effects in the hippocampal CA1 region following GCI. Mechanistically, the beneficial effects of genistein appear to be mediated by enhanced eNOS phosphorylation/activation and nitric oxide (NO)-mediated thiol modification of Keap1, with subsequent upregulation of the Nrf2/HO-1 antioxidative signaling pathway and a resultant attenuation of oxidative stress.

[Effect of N-acetyl-seryl-aspartyl-lysyl-proline on differentiation from pulmonary fibroblast to myofibroblast mediated by Rho-associated coiled-coil forming protein kinase pathway].

OBJECTIVE: To investigate whether N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) can inhibit the differentiation of pulmonary fibroblasts into myofibroblasts by regulating Rho-associated coiled-coil forming protein kinase (ROCK) pathway mediated by transforming growth factor-ß1 (TGF-ß1). METHODS: Primary culture of pulmonary fibroblasts was performed by trypsinization method. Four generations of pulmonary fibroblasts were divided into control group, TGF-ß-induced differentiation group, Y-27632 treatment group, and Ac-SDKP treatment group. The intracellular distributions of ROCK, serum response factor (SRF), and α-smooth muscle actin (α-SMA) were observed by confocal laser scanning microscopy. The protein expression of ROCK, SFR, α-SMA, and type I and type III collagen in pulmonary fibroblasts was measured by Western blot. The mRNA expression of ROCK, SFR, and α-SMA was measured by real-time quantitative PCR. RESULTS: Compared with the control group, the pulmonary fibroblasts stimulated by TGF-ß1 had a lot of α-SMA antibody-labeled myofilaments in parallel or cross arrangement, as observed by confocal laser scanning microscopy, and the mRNA and protein expression of ROCK, SRF, and α-SMA and protein expression of type I and type III collagen increased significantly after 6, 12, and 24 h of stimulation (P < 0.05). Compared with the TGF-ß1-induced differentiation group, the Y-27632 treatment group and Ac-SDKP treatment group had significantly decreased mRNA and protein expression of ROCK, SRF, and α-SMA and protein expression of type I and type III collagen at the same time point (P < 0.05). CONCLUSION: Ac-SDKP can inhibit the differentiation of pulmonary fibroblasts into myofibroblasts and the synthesis of collagen in rats by regulating the ROCK pathway mediated by TGF-ß1. That may be one of the mechanisms by which Ac-SDKP acts against (silicotic) pulmonary fibrosis.

[Regulating effect of N-acetyl-seryl-aspartyl-lysyl-proline on activation of c-jun N-terminal kinase pathway in rats with silicosis].

OBJECTIVE: To investigate the regulatory effect of N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP) on the activation of c-jun N-terminal kinase (JNK) signal transduction pathway and its role in silicotic fibrosis. METHODS: A rat model of silicosis was developed by intratracheal instillation. Sixty rats were randomly divided into 4-week control group (n = 10), 8-week control group (n = 10), 4-week silicosis model group (n = 10), 8-week silicosis model group (n = 10), AcSDKP treatment group (n = 10), and AcSDKP prevention group (n = 10). The content of hydroxyproline in lung tissue was measured using a p-dimethylaminoben-zaldehyde reagent; the expression levels of transforming growth factor (TGF)-beta 1 (TGF-ß1), phospho-JNK, JNK, and c-jun in lung tissue were measured by Western blot. The lung fibroblasts from neonatal rats were cultured, and the 4th generation of cells were used in the experiment; these cells were divided into control group, TGF-ß1 stimulation group, SP600125 intervention group, and AcSDKP intervention group. The distributions of phospho-JNK and c-jun in lung fibroblasts were observed by immunocytochemistry; the expression levels of type I collagen and type III collagen in lung fibroblasts were measured by Western blot. RESULTS: The expression levels of TGF-ß1, phospho-JNK, and c-jun and the content of hydroxyproline in the AcSDKP treatment group were 70.60%, 78.03%, 79.85%, and 71.28%, respectively, of those in the 4-week silicosis model group (P < 0.05) and 77.99%, 66.73%, 69.94%, and 64.82%, respectively, of those in the 8-week silicosis model group (P < 0.05); the expression levels of TGF-ß1, phospho-JNK, and c-jun and the content of hydroxyproline in the AcSDKP prevention group were 84.56%, 61.18%, 64.73%, and 74.96%, respectively, of those in the 8-week silicosis model group (P < 0.05). The expression levels of phospho-JNK and c-jun in the AcSDKP intervention group were 54.59% and 55.56%, respectively, of those in the TGF-ß1 stimulation group; the expression levels of type I collagen and type III collagen in the AcSDKP intervention group were 79.9% and 84.4%, respectively, of those in the TGF-ß1 stimulation group (P < 0.05). CONCLUSION: AcSDKP exerts anti-silicotic fibrosis effect probably by inhibiting the activation of JNK signal transduction pathway mediated by TGF-ß1 and the deposition of interstitial collagen.

Silica nanoparticles induces sperm granuloma formation and blood-epididymal barrier disruption via the p38 MAPK pathway in mice.

Previous researches have demonstrated that the silica nanoparticles (SiNPs), which are widely used in all aspects of life, are hazardous to the male reproductive system. However, the cellular and molecular mechanism underlying SiNPs toxicity to the epididymis remain unclear. In this present study, a total of 60 male mice were separated into 4 groups and then treated to SiNPs for 7 consecutive days at a dose of 0, 2.5, 10, and 20 mg/kg body weight. The results showed that SiNPs could alter the histological structure of epididymis and induce sperm granuloma formation, leading to decreased sperm quality and quantity. In addition, the ultrastructure and permeability of blood-epididymal barrier (BEB) were impaired after exposure to SiNPs, and a significant downregulation of integral membrane proteins at the BEB was detected. SiNPs were also found to raise the percentage of macrophages in the epithelium and interstitium of the epididymis, followed by increased expression of pro-inflammatory molecules including TNF α, IL-1ß, and IL-6. Meanwhile, SiNPs induced oxidative stress in epididymis, as shown by the markedly elevated generation of reactive oxygen species (ROS) and malondialdehyde (MDA) and upregulated activity of superoxide dismutase (SOD). Further study showed that SiNPs activated the p38 MAPK signaling pathway, which accelerated clathrin-mediated endocytosis of integral membrane proteins and perturb vesicular trafficking. Taken together, exposure to SiNPs could induce sperm granuloma formation and impair the integrity of BEB in mice through activating the p38 MAPK pathway.

Critical Role of Position 10 Residue in the Polymyxin Antimicrobial Activity.

Polymyxins (polymyxin B and colistin) are lipopeptide antibiotics used as a last-line treatment for life-threatening multidrug-resistant (MDR) Gram-negative bacterial infections. Unfortunately, their clinical use has been affected by dose-limiting toxicity and increasing resistance. Structure-activity (SAR) and structure-toxicity (STR) relationships are paramount for the development of safer polymyxins, albeit very little is known about the role of the conserved position 10 threonine (Thr) residue in the polymyxin core scaffold. Here, we synthesized 30 novel analogues of polymyxin B1 modified explicitly at position 10 and examined the antimicrobial activity against Gram-negative bacteria and in vivo toxicity and performed molecular dynamics simulations with bacterial outer membranes. For the first time, this study revealed the stereochemical requirements and role of the ß-hydroxy side chain in promoting the correctly folded conformation of the polymyxin that drives outer membrane penetration and antibacterial activity. These findings provide essential information for developing safer and more efficacious new-generation polymyxin antibiotics.