iTRAQ-Based Proteomics Revealed the Bactericidal Mechanism of Sodium New Houttuyfonate against Streptococcus pneumoniae

The erythromycin polyketide compound TMC-154 stimulates ROS generation to exert antibacterial effects against Streptococcus pyogenes

The erythromycin polyketide compound TMC-154 is a secondary metabolite that is isolated from the rhizospheric fungus Clonostachys rogersoniana associated with Panax notoginseng, which possesses antibacterial activity. However, its antibacterial mechanism has not been investigated thus far. In this study, proteomics coupled with bioinformatics approaches was used to explore the antibacterial mechanism of TMC-154. KEGG pathway enrichment analysis indicated that eight signaling pathways were associated with TMC-154, including oxidative phosphorylation, cationic antimicrobial peptide (CAMP) resistance, benzoate degradation, heme acquisition systems, glycine/serine and threonine metabolism, beta-lactam resistance, ascorbate and aldarate metabolism, and phosphotransferase system (PTS). Cell biology experiments confirmed that TMC-154 could induce reactive oxygen species (ROS) generation in Streptococcus pyogenes; moreover, TMC-154-induced antibacterial effects could be blocked by the inhibition of ROS generation with the antioxidant N-acetyl L-cysteine. In addition, TMC-154 combined with ciprofloxacin or chloramphenicol had synergistic antibacterial effects. These findings indicate the potential of TMC-154 as a promising drug to treat S. pyogenes infections. SIGNIFICANCE: Streptococcus pyogenes is a nearly ubiquitous human pathogen that causes a variety of diseases ranging from mild pharyngitis and skin infection to fatal sepsis and toxic heat shock syndrome. With the increasing incidence of known antibiotic resistance, there is an urgent need to find novel drugs with good antibacterial activity against S. pyogenes. In this study, we found that TMC-154, a secondary metabolite from the fungus Clonostachys rogersoniana, inhibited the growth of various bacteria, including Staphylococcus aureus, S. pyogenes, Streptococcus mutans, Pseudomonas aeruginosa and Vibrio parahemolyticus. Proteomic analysis combined with cell biology experiments revealed that TMC-154 stimulated ROS generation to exert antibacterial effects against S. pyogenes. This study provides potential options for the treatment of S. pyogenes infections in the future.

Proteomics reveals energy limitation and amino acid consumption as antibacterial mechanism of linalool against Shigella sonnei and its application in fresh beef preservation

Meat is often contaminated by food-borne pathogens, resulting in significant economic losses. Linalool from plant essential oils (EOs) has been reported to have excellent antibacterial properties. Therefore, this study aims to elucidate the mechanism of linalool against Shigella sonnei (S. sonnei) based on proteomic and physiological indicators. The results indicated that linalool severely perturbed the expression levels of intracellular proteins, of which 208 were up-regulated and 49 were down-regulated. Moreover, linalool exerted its inhibitory effect mainly through the induction of amino acid limitation and insufficient energy levels based on the pathways involved in differential expressed proteins (DEPs). After 8 h, alkaline phosphatase (AKP) leakage increased 20.96 and 21.52-fold in the MIC and 2MIC groups while protein leakage increased 2.17 and 2.50-fold, respectively, which revealed the potential of linalool on cell structure damage combined with nucleic acid leakage. In addition, the ATP content decreased to 36.92% and 18.84% in the MIC and 2MIC groups, respectively when processed for 8 h. In particular, linalool could effectively control the quality change of fresh beef by measuring pH, total volatile basic nitrogen (TVB-N), total viable counts (TVC) while not affecting its sensory acceptability based on the result of sensory evaluation. This research provides theoretical insights for the development of linalool as a new natural antibacterial agent.

Sodium New Houttuyfonate Induces Apoptosis of Breast Cancer Cells via ROS/PDK1/AKT/GSK3β Axis

BACKGROUND

Sodium new houttuyfonate (SNH) has been reported to have anti-inflammatory, anti-fungal, and anti-cancer effects. However, few studies have investigated the effect of SNH on breast cancer. The aim of this study was to investigate whether SNH has therapeutic potential for targeting breast cancer.

METHODS

Immunohistochemistry and Western blot analysis were used to examine the expression of proteins, flow cytometry was used to detect cell apoptosis and ROS levels, and transmission electron microscopy was used to observe mitochondria.

RESULTS

Differentially expressed genes (DEGs) between breast cancer-related gene expression profiles (GSE139038 and GSE109169) from GEO DataSets were mainly involved in the immune signaling pathway and the apoptotic signaling pathway. According to in vitro experiments, SNH significantly inhibited the proliferation, migration, and invasiveness of MCF-7 (human cells) and CMT-1211 (canine cells) and promoted apoptosis. To explore the reason for the above cellular changes, it was found that SNH induced the excessive production of ROS, resulting in mitochondrial impairment, and then promoted apoptosis by inhibiting the activation of the PDK1-AKT-GSK3β pathway. Tumor growth, as well as lung and liver metastases, were suppressed under SNH treatment in a mouse breast tumor model.

CONCLUSIONS

SNH significantly inhibited the proliferation and invasiveness of breast cancer cells and may have significant therapeutic potential in breast cancer.

Sodium New Houttuyfonate Inhibits Cancer-Promoting Fusobacterium nucleatum (Fn) to Reduce Colorectal Cancer Progression

Colorectal cancer (CRC) is a major cause of morbidity and mortality worldwide. Recent studies showed that the common anaerobe Fusobacterium nucleatum (Fn) is closely associated with a higher risk for carcinogenesis, metastasis, and chemoresistance of CRC. However, there is no specific antimicrobial therapy for CRC treatment. Herbal medicine has a long history of treating diseases with remarkable effects and is attracting extensive attention. In this study, we tested six common phytochemicals for their antimicrobial activities against Fn and whether anti-Fn phytochemicals can modulate CRC development associated with Fn. Among these antimicrobials, we found that SNH showed the highest antimicrobial activity and little cytotoxicity toward cancer cells and normal cells in vitro and in vivo. Mechanistically, SNH may target membrane-associated FadA, leading to FadA oligomerization, membrane fragmentation and permeabilization. More importantly, SNH blocked the tumor-promoting activity of Fn and Fn-associated cancer-driven inflammation, thus improving the intestinal barrier damaged by Fn. SNH reduced Fn load in the CRC-cells-derived mice xenografts with Fn inoculation and significantly inhibited CRC progression. Our data suggest that SNH could be used for an antimicrobial therapy that inhibits Fn and cancer-driven inflammation of CRC. Our results provide an important foundation for future gut microbiota-targeted clinical treatment of CRC.

Proteomic Investigation of the Antibacterial Mechanism of Cefiderocol against Escherichia coli

This study aimed to investigate the antibacterial mechanism of cefiderocol (CFDC) using data-independent acquisition quantitative proteomics combined with cellular and molecular biological assays. Numerous differentially expressed proteins related to the production of NADH, reduced cofactor flavin adenine dinucleotide (FADH2), NADPH and reactive oxygen species (ROS), iron-sulfur cluster binding, and iron ion homeostasis were found to be upregulated by CFDC. Furthermore, parallel reaction monitoring analysis validated these results. Meanwhile, we confirmed that the levels of NADH, ROS, H2O2, and iron ions were induced by CFDC, and the sensitivity of Escherichia coli to CFDC was inhibited by the antioxidant vitamin C, N-acetyl-l-cysteine, and deferoxamine. Moreover, deferoxamine also suppressed the H2O2 stress induced by CFDC. In addition, knockout of the NADH-quinone oxidoreductase genes (nuoA, nuoC, nuoE, nuoF, nuoG, nuoJ, nuoL, nuoM) in the respiratory chain attenuated the sensitivity of E. coli to CFDC far beyond the effects of cefepime and ceftazidime; in particular, the E. coli BW25113 ΔnuoJ strain produced 60-fold increases in MIC to CFDC compared to that of the wild-type E. coli BW25113 strain. The present study revealed that CFDC exerts its antibacterial effects by inducing ROS stress by elevating the levels of NADH and iron ions in E. coli. IMPORTANCE CFDC was the first FDA-approved siderophore cephalosporin antibiotic in 2019 and is known for its Trojan horse tactics and broad antimicrobial activity against Gram-negative bacteria. However, its antibacterial mechanism is not fully understood, and whether it has an impact on in vivo iron ion homeostasis remains unknown. To comprehensively reveal the antibacterial mechanisms of CFDC, data-independent acquisition quantitative proteomics combined with cellular and molecular biological assays were performed in this study. The findings will further facilitate our understanding of the antibacterial mechanism of CFDC and may provide a theoretical foundation for controlling CFDC resistance in the future.

iTRAQ-based proteomics revealed baicalein enhanced oxidative stress of Candida albicans by up-regulating CPD2 expression

Baicalein could inhibit the growth and biofilm formation of Candida albicans, the most common clinical fungal pathogen. However, the antifungal mechanism of baicalein has not been elucidated. In this study, isobaric tags for relative and absolute quantification (iTRAQ) was used to verify the mechanism of antifungal fluconazole and baicalein. A total of 58 common proteins were detected in cells treated with fluconazole. These proteins encompassed fluconazole-targeted sterol synthesis pathway, including Erg11p, Erg6p, Erg3p, Erg25p, Erg5p, Erg10p and Ncp1p. Next, iTRAQ was applied to the comparison of baicalein-treated C. albicans proteins, which detected 16 common proteins. The putative NADH dehydrogenase Cpd2p and the ATP-binding cassette transporter Snq2p were the most up-regulated proteins with the treatment of baicalein. Our results showed that CPD2 disruption elevated C. albicans resistance to baicalein significantly both in vitro and in vivo. Further in-depth studies revealed that CPD2 disruption reduced the activation of C. albicans metacaspase and partially restored the mitochondrial membrane potential reduction caused by the treatment of baicalein, which indicated that CPD2 was involved in the apoptosis induced by baicalein. Consistently, under the treatment of baicalein, CPD2Δ/Δ mutant produced lower reactive oxygen species (ROS) that was critical in causing oxidative damage and apoptosis in C. albicans. These results indicated that baicalein could increase intracellular oxidative damage by up-regulating the expression of Cpd2p so as to inhibit the growth of C. albicans, which provides new insights for investigating the antifungal target of baicalein.

Antifungal Activity of Sodium New Houttuyfonate Against Aspergillus fumigatus in vitro and in vivo

Aspergillus fumigatus is an important pathogen causing invasive aspergillosis, which is associated with high morbidity and mortality in immunocompromised people. However, the treatment of A. fumigatus infection is a growing challenge, owing to the limited availability antifungal agents and the continual emergence of drug-resistant strains. Drug repurposing is a potential strategy to solve this current problem. Sodium new houttuyfonate (SNH), derived from houttuynin, extracted from Houttuynia cordata, has anti-bacterial and anti-Candida albicans effects. However, whether it has anti-A. fumigatus activity had not been reported. In this study, the antifungal properties of SNH against A. fumigatus, including the standard strain AF293, itraconazole resistant clinical strains, and voriconazole resistant clinical strains, were evaluated in vitro and in vivo. Moreover, the potential mechanism of SNH was characterized. SNH exhibited significant fungicidal activity toward various A. fumigatus strains. SNH also inhibited fungal growth, sporulation, conidial germination and pigment formation, and biofilm formation. Further investigations revealed that SNH interfered with the A. fumigatus cell steroid synthesis pathway, as indicated by transcriptomic and quantitative real-time polymerase chain reaction analyses, and inhibited ergosterol synthesis, as indicated by cell membrane stress assays and ergosterol quantification. Moreover, daily gastric gavage of SNH significantly decreased the fungal burden in mice with disseminated infection (kidney, liver, and lung) and local tissue damage. In addition, the application of SNH downregulated the production of IL-6 and IL-17A. Together, these findings provided the first confirmation that SNH may be a promising antifungal agent for the treatment of A. fumigatus infection.

Identification and Tetramer Structure of Hemin-Binding Protein SPD_0310 Linked to Iron Homeostasis and Virulence of Streptococcus pneumoniae

Iron and iron-containing compounds are essential for bacterial virulence and host infection. Hemin is an important supplement compound for bacterial survival in an iron-deficient environment. Despite strong interest in hemin metabolism, the detailed mechanism of hemin transportation in Gram-positive bacteria is yet to be reported. The results of our study revealed that the homologous proteins of SPD_0310 were significantly conservative in Gram-positive bacteria (P < 0.001), and these proteins were identified as belonging to an uncharacterized protein family (UPF0371). The results of thermodynamic and kinetic studies have shown that SPD_0310 has a high hemin-binding affinity. Interestingly, we found that the crystal structure of SPD_0310 presented a homotetramer conformation, which is required for hemin binding. SPD_0310 can interact with many hemin-binding proteins (SPD_0090, SPD_1609, and GAPDH) located on the cell surface, which contributes to hemin transfer to the cytoplasm. It also has a high affinity with other iron transporters in the cytoplasm (SPD_0226 and SPD_0227), which facilitates iron redistribution in cells. More importantly, the knockout of the spd_0310 gene (Δspd_0310) resulted in a decrease in the iron content and protein expression levels of many bacterial adhesion factors. Moreover, the animal model showed that the Δspd_0310 strain has a lower virulence than the wild type. Based on the crystallographic and biochemical studies, we inferred that SPD_0310 is a hemin intermediate transporter which contributes to iron homeostasis and further affects the virulence of Streptococcus pneumoniae in the host. Our study provides not only an important theoretical basis for the in-depth elucidation of the hemin transport mechanism in bacteria but also an important candidate target for the development of novel antimicrobial agents based on metal transport systems. IMPORTANCE Iron is an essential element for bacterial virulence and infection of the host. The detailed hemin metabolism in Gram-positive bacteria has rarely been studied. SPD_0310 belongs to the UPF0371 family of proteins, and results of homology analysis and evolutionary tree analysis suggested that it was widely distributed and highly conserved in Gram-positive bacteria. However, the function of the UPF0371 family remains unknown. We successfully determined the crystal structure of apo-SPD_0310, which is a homotetramer. We found that cytoplasmic protein SPD_0310 with a special tetramer structure has a strong hemin-binding ability and interacts with many iron transporters, which facilitates hemin transfer from the extracellular space to the cytoplasm. The results of detailed functional analyses indicated that SPD_0310 may function as a hemin transporter similar to hemoglobin in animals and contributes to bacterial iron homeostasis and virulence. This study provides a novel target for the development of antimicrobial drugs against pathogenic Gram-positive bacteria.

Inhibitory effects of sodium new houttuyfonate on growth and biofilm formation of Streptococcus mutans

The present study aimed to assess the impact of sodium new houttuyfonate (SNH) on growth and biofilm formation of Streptococcus mutans, and the combinatorial effects of SNH with cariostatic agents. The effects of SNH on S. mutans planktonic cultures were assessed by growth curve assay. The effects of SNH on S. mutans biofilm and extracellular polysaccharides (EPS) production were observed via crystal violet (CV) assay, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, colony-forming unit (CFU) counting assay, scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Quantitative real-time polymerase chain reaction (qPCR) was applied to investigate the regulatory effects of SNH on the expression of virulence genes of S. mutans. Checkerboard microdilution assay was performed to investigate the combinatorial effects of SNH with two common cariostatic agents. SNH acted as an inhibitor on planktonic cell growth, biofilm formation and EPS production of S. mutans. SNH also downregulated the expression of gtfBCD and comDE systems and exhibited synergism with chlorhexidine (CHX). In conclusion, this study indicated a possibility for SNH to become an anticaries agents by its antimicrobial activity and synergistic effects with CHX against S. mutans.

Proteomic Investigation of the Antibacterial Mechanism of trans-Cinnamaldehyde against Escherichia coli

Trans-Cinnamaldehyde (TC) is a widely used food additive, known for its sterilization, disinfection, and antiseptic properties. However, its antibacterial mechanism is not completely understood. In this study, quantitative proteomics was performed to investigate differentially expressed proteins (DEPs) in Escherichia coli in response to TC treatment. Bioinformatics analysis suggested aldehyde toxicity, acid stress, oxidative stress, interference of carbohydrate metabolism, energy metabolism, and protein translation as the bactericidal mechanism. E. coli BW25113ΔyqhD, ΔgldA, ΔbetB, ΔtktB, ΔgadA, ΔgadB, ΔgadC, and Δrmf were used to investigate the functions of DEPs through biochemical methods. The present study revealed that TC exerts its antibacterial effects by inducing the toxicity of its aldehyde group producing acid stress. These findings will contribute to the application of TC in the antibacterial field.

Proteomic Profiling Change and Its Implies in the Early Mycosis Fungoides (MF) Using Isobaric Tags for Relative and Absolute Quantification (iTRAQ)

Purpose

Mycosis fungoides (MF) is the most common T-cell lymphoma, with indolent biologic behavior in the early stage and features of invasive in the tumor stage. The diagnosis of MF is still ambiguous and difficult. We focused on the proteomic profiling change in the pathogenesis of early MF and identified candidate biomarkers for early diagnosis.

Methods

We collected peripheral blood samples of MF patients and healthy individuals (HI) performed proteomic profiling analysis using isobaric tags for relative and absolute quantification (iTRAQ) platform. Differently expressed proteins (DEPs) were filtered, and involved biological functions were analyzed through Gene Ontology (GO) and Ingenuity Pathway Analysis (IPA) software.

Results

We identified 78 DEPs including fifty proteins were upregulated and 28 proteins were downregulated in the MF group with HI as a control. Total DEPs were analyzed according to the biological regulation and metabolic process through GO analysis. The pathways of LXR/RXR activation and FXR/RXR activation were significantly activated, in which APOH, CLU, and ITIH4 were involved. The top annotated disease and function network was (Cancer, Organismal Injury and Abnormalities, Reproductive System Disease), with a key node CLU. These DEPs were involved in cancer, including thyroid carcinoma, head and neck carcinoma, and cancer of secretory structure, in which CLU, GNAS, and PKM played an indirect role in the occurrence and development of cancer. Relevant causal network was IL12 (family), which is related to GNAS, PKM, and other DEPs.

Conclusion

Proteomic profiling of early-stage MF provided candidate protein biomarkers such as CLU, GNAS, and PKM, which benefit the early diagnosis and understanding of the mechanism of MF development. Besides, lipid metabolism may be one of the pathogenesis of MF, and IL12 was a potential marker for the diagnosis and treatment of early MF.

Sodium New Houttuyfonate Inhibits Candida albicans Biofilm Formation by Inhibiting the Ras1-cAMP-Efg1 Pathway Revealed by RNA-seq

Here, we aim to investigate the antifungal effect and mechanism of action of sodium new houttuyfonate (SNH) against Candida albicans. Microdilution analysis results showed that SNH possesses potent inhibitory activity against C. albicans SC5314, with a MIC₈₀ of 256 μg/mL. Furthermore, we found that SNH can effectively inhibit the initial adhesion of C. albicans. Inverted microscopy, crystal violet staining, scanning electron microscopy and confocal laser scanning microscopy results showed that morphological changes during the transition from yeast to hypha and the biofilm formation of C. albicans are repressed by SNH treatment. We also found that SNH can effectively inhibit the biofilm formation of clinical C. albicans strains (Z103, Z3044, Z1402, and Z1407) and SNH in combination with fluconazole, berberine chloride, caspofungin and itraconazole antifungal agents can synergistically inhibit the biofilm formation of C. albicans. Eukaryotic transcriptome sequencing and qRT-PCR results showed that SNH treatment resulted in significantly down-regulated expression in several biofilm formation related genes in the Ras1-cAMP-Efg1 pathway (ALS1, ALA1, ALS3, EAP1, RAS1, EFG1, HWP1, and TEC1) and significantly up-regulated expression in yeast form-associated genes (YWP1 and RHD1). We also found that SNH can effectively reduce the production of key messenger cAMP in the Ras1-cAMP-Efg1 pathway. Furthermore, using Galleria mellonella as an in vivo model we found that SNH can effectively treat C. albicans infection in vivo. Our presented results suggest that SNH exhibits potential antibiofilm effects related to inhibiting the Ras1-cAMP-Efg1 pathway in the biofilm formation of C. albicans.

Transcriptomic and proteomic profiling response of methicillin-resistant Staphylococcus aureus (MRSA) to a novel bacteriocin, plantaricin GZ1-27 and its inhibition of biofilm formation

Methicillin-resistant Staphylococcus aureus (MRSA) has become a worrisome superbug, due to its wide distribution and multidrug resistance. To characterize effects of a newly identified plantaricin GZ1-27 on MRSA, transcriptomic and proteomic profiling of MRSA strain ATCC43300 was performed in response to sub-MIC (16 μg/mL) plantaricin GZ1-27 stress. In total, 1090 differentially expressed genes (padj < 0.05) and 418 differentially expressed proteins (fold change > 1.2, p < 0.05) were identified. Centralized protein expression clusters were predicted in biological functions (biofilm formation, DNA replication and repair, and heat-shock) and metabolic pathways (purine metabolism, amino acid metabolism, and biosynthesis of secondary metabolites). Moreover, a capacity of inhibition MRSA biofilm formation and killing biofilm cells were verified using crystal violet staining, scanning electron microscopy, and confocal laser-scanning microscopy. These findings yielded comprehensive new data regarding responses induced by plantaricin and could inform evidence-based methods to mitigate MRSA biofilm formation.

SPD_1495 Contributes to Capsular Polysaccharide Synthesis and Virulence in Streptococcus pneumoniae

Capsular polysaccharide is a key factor underlying the virulence of Streptococcus pneumoniae in human diseases. Thus, a deep understanding of capsular polysaccharide synthesis is essential for uncovering the pathogenesis of S. pneumoniae infection. In this study, we show that protein SPD_1495 interacts with phosphorylated ComE to negatively regulate the formation of capsular polysaccharide. Deletion of spd1495 increased capsular polysaccharide synthesis and thereby enhanced bacterial virulence. These findings further reveal the synthesis mechanism of capsular polysaccharide and provide new insight into the biology of this clinically important bacterium.

Streptococcus pneumoniae, a Gram-positive human pathogen, causes a series of serious diseases in humans. SPD_1495 from S. pneumoniae is annotated as a hypothetical ABC sugar-binding protein in the NCBI database, but there are few reports on detailed biological functions of SPD_1495. To fully study the influence of SPD_1495 on bacterial virulence in S. pneumoniae, we constructed a deletion mutant (D39Δspd1495) and an overexpressing strain (D39spd1495+). Comparative analysis of iTRAQ-based quantitative proteomic data of the wild-type D39 strain (D39-WT) and D39Δspd1495 showed that several differentially expressed proteins that participate in capsular polysaccharide synthesis, such as Cps2M, Cps2C, Cps2L, Cps2T, Cps2E, and Cps2D, were markedly upregulated in D39Δspd1495. Subsequent transmission electron microscopy and uronic acid detection assay confirmed that capsular polysaccharide synthesis was enhanced in D39Δspd1495 compared to that in D39-WT. Moreover, knockout of spd1495 resulted in increased capsular polysaccharide synthesis, as well as increased bacterial virulence, as confirmed by the animal study. Through a coimmunoprecipitation assay, surface plasmon resonance, and electrophoretic mobility shift assay, we found that SPD_1495 negatively regulated cps promoter expression by interacting with phosphorylated ComE, a negative transcriptional regulator for capsular polysaccharide formation. Overall, this study suggested that SPD_1495 negatively regulates capsular polysaccharide formation and thereby enhances bacterial virulence in the host. These findings also provide valuable insights into understanding the biology of this clinically important bacterium.

IMPORTANCE Capsular polysaccharide is a key factor underlying the virulence of Streptococcus pneumoniae in human diseases. Thus, a deep understanding of capsular polysaccharide synthesis is essential for uncovering the pathogenesis of S. pneumoniae infection. In this study, we show that protein SPD_1495 interacts with phosphorylated ComE to negatively regulate the formation of capsular polysaccharide. Deletion of spd1495 increased capsular polysaccharide synthesis and thereby enhanced bacterial virulence. These findings further reveal the synthesis mechanism of capsular polysaccharide and provide new insight into the biology of this clinically important bacterium.

Herba Houttuyniae Extract Benefits Hyperlipidemic Mice via Activation of the AMPK/PGC-1α/Nrf2 Cascade

Hyperlipidemia is associated with metabolic disorders, but the detailed mechanisms and related interventions remain largely unclear. As a functional food in Asian diets, Herba houttuyniae has been reported to have beneficial effects on health. The present research was to investigate the protective effects of Herba houttuyniae aqueous extract (HAE) on hyperlipidemia-induced liver and heart impairments and its potential mechanisms. Male C57BL/6J mice were administered with 200 or 400 mg/kg/day HAE for 9 days, followed by intraperitoneal injection with 0.5 g/kg poloxamer 407 to induce acute hyperlipidemia. HAE treatment significantly attenuated excessive serum lipids and tissue damage markers, prevented hepatic lipid deposition, improved cardiac remodeling, and ameliorated hepatic and cardiac oxidative stress induced by hyperlipidemia. More importantly, NF-E2 related factor (Nrf2)-mediated antioxidant and peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α)-mediated mitochondrial biogenesis pathways as well as mitochondrial complex activities were downregulated in the hyperlipidemic mouse livers and hearts, which may be attributable to the loss of adenosine monophosphate (AMP)-activated protein kinase (AMPK) activity: all of these changes were reversed by HAE supplementation. Our findings link the AMPK/PGC-1α/Nrf2 cascade to hyperlipidemia-induced liver and heart impairments and demonstrate the protective effect of HAE as an AMPK activator in the prevention of hyperlipidemia-related diseases.

Photocatalytic Protein Damage by Silver Nanoparticles Circumvents Bacterial Stress Response and Multidrug Resistance

Silver nanoparticles (AgNPs) are known for their broad-spectrum antibacterial properties, especially against antibiotic-resistant bacteria. However, the bactericidal mechanism of AgNPs remains unclear. In this study, we found that the bactericidal ability of AgNPs is induced by light. In contrast to previous postulates, visible light is unable to trigger silver ion release from AgNPs or to promote AgNPs to induce reactive oxygen species (ROS) in Escherichia coli In fact, we revealed that light excited AgNPs to induce protein aggregation in a concentration-dependent manner in E. coli, indicating that the bactericidal ability of AgNPs relies on the light-catalyzed oxidation of cellular proteins via direct binding to proteins, which was verified by fluorescence spectra. AgNPs likely absorb the light energy and transfer it to the proteins, leading to the oxidation of proteins and thus promoting the death of the bacteria. Isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomics revealed that the bacteria failed to develop effective resistance to the light-excited AgNPs. This direct physical mechanism is unlikely to be counteracted by any known drug resistance mechanisms of bacteria and therefore may serve as a last resort against drug resistance. This mechanism also provides a practical hint regarding the antimicrobial application of AgNPs-light exposure improves the efficacy of AgNPs.IMPORTANCE Although silver nanoparticles (AgNPs) are well known for their antibacterial properties, the mechanism by which they kill bacterial cells remains a topic of debate. In this study, we uncovered the bactericidal mechanism of AgNPs, which is induced by light. We tested the efficacy of AgNPs against a panel of antimicrobial-resistant pathogens as well as Escherichia coli under conditions of light and darkness and revealed that light excited the AgNPs to promote protein aggregation within the bacterial cells. Our report makes a significant contribution to the literature because this mechanism bypasses microbial drug resistance mechanisms, thus presenting a viable option for the treatment of multidrug-resistant bacteria.

Dirhodium (II) complex interferes with iron-transport system to exert antibacterial action against Streptococcus pneumoniae

Drug resistance in bacteria is becoming a significant threat to global public health, and the development of novel and efficient antibacterial compounds is urgently needed. Recently, rhodium complexes have attracted attention as antimicrobial agents, yet their antibacterial mechanism remains unknown. In this study, we observed that the dirhodium (II) complex Rh₂Ac₄ inhibited Streptococcus. pneumoniae growth without significant cytotoxic side-effects on host cells in vitro. We subsequently investigated the antibacterial mechanism of Rh₂Ac₄ using iTRAQ-based proteomics combined with cellular and biochemical assays. Bioinformatics analysis on the proteomic alterations demonstrated that six molecular functional groups, including metal ion binding and twelve metabolic pathways, were significantly affected after treatment with Rh₂Ac₄. The interaction network analysis of metal ion binding proteins suggested that Rh₂Ac₄ decreased the protein expression levels of SPD_1652, SPD_1590 and Gap, which are associated with haem uptake/metabolism. Cellular and biochemical assays further confirmed that Rh₂Ac₄ could be taken up by bacteria via the PiuABCD haem-uptake system. The structurally similar Rh complex may compete with Fe-haem to decrease Fe-uptake via the PiuABCD system, disrupting iron metabolism to exert its antibacterial activity against S. pneumoniae. These data indicate that Rh₂Ac₄ is a promising new drug for the treatment of S. pneumoniae infections.

Rapid Trace Detection and Isomer Quantitation of Pesticide Residues via Matrix-Assisted Laser Desorption/Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTICR-MS) has been applied for rapid, sensitive, undisputed, and quantitative detection of pesticide residues on fresh leaves with little sample pretreatment. Various pesticides (insecticides, bactericides, herbicides, and acaricides) are detected directly in the complex matrix with excellent limits of detection down to 4 μg/L. FTICR-MS could unambiguously identify pesticides with tiny mass differences (∼0.017 75 Da), thereby avoiding false-positive results. Remarkably, pesticide isomers can be totally discriminated by use of diagnostic fragments, and quantitative analysis of pesticide isomers is demonstrated. The present results expand the horizons of the MALDI-FTICR-MS platform in the reliable determination of pesticides, with integrated advantages of ultrahigh mass resolution and accuracy. This method provides growing evidence for the resultant detrimental effects of pesticides, expediting the identification and evaluation of innovative pesticides.

Direct and indirect approaches to identify drug modes of action

Phenotypic assays are becoming increasingly more common among drug discovery practices, expanding drug target diversity as lead compounds identified through such screens are not limited to known targets. While increasing diversity is beneficial to the drug discovery process and the fight against disease, the unknown modes of action of new lead compounds can hamper drug discovery as, in most cases, the process of lead compound optimization is made difficult due to the unknown nature of the target; blindly changing substituents can prove fruitless due to the inexhaustible number of potential combinations, and it is therefore desirable to rapidly identify the targets of lead compounds developed through phenotypic screening. In addition, leads identified through target-based screening often have off-target effects that contribute towards drug toxicity, and by identifying those secondary targets, the drugs can be improved. However, the identification of a leads mode of action is far from trivial and now represents a major bottleneck in the drug discovery pipeline. This review looks at some of the recent developments in the identification of drug modes of action, focusing on phenotype-based methods using metabolomics, proteomics, transcriptomics, and genomics to detect changes in phenotype in response to the presence of the drug, and affinity-based methods using modified/unmodified drug as bait to capture and identify targets. © 2017 IUBMB Life, 70(1):9-22, 2018.

Jolkinolide B induces apoptosis of colorectal carcinoma through ROS-ER stress-Ca2+-mitochondria dependent pathway

Colorectal carcinoma (CRC) remains one of the leading causes of death in cancer-related diseases. In this study, we aimed to investigate the anticancer effect of Jolkinolide B (JB), a bioactive diterpenoid component isolated from the dried roots of Euphorbia fischeriana Steud, on CRC cells and its underlying mechanisms. We found that JB suppressed the cell viability and colony formation of CRC cells, HT29 and SW620. Annexin V/PI assay revealed that JB induced apoptosis in CRC cells, which was further confirmed by the increased expression of cleaved-caspase3 and cleaved-PARP. iTRAQ-based quantitative proteomics was performed to identify JB-regulated proteins in CRC cells. Gene Ontology (GO) analysis revealed that these JB-regulated proteins were mainly involved in ER stress response, which was evidenced by the expression of ER stress marker proteins, HSP90, Bip and PDI. Moreover, we found that JB provoked the generation of reactive oxygen species (ROS), and that inhibition of the ROS generation with N-acetyl L-cysteine could reverse the JB-induced apoptosis. Confocal microscopy and flow cytometry showed that JB treatment enhanced intracellular and mitochondrial Ca²⁺ level and JC-1 assay revealed a loss of mitochondrial membrane potential in CRC after JB treatment. The mitochondrial Ca²⁺ uptake and depolarization can be blocked by Ruthenium Red (RuRed), an inhibitor of mitochondrial Ca²⁺ uniporter. Taken together, we demonstrated that JB exerts its anticancer effect by ER stress-Ca²⁺-mitochondria signaling, suggesting the promising chemotherapeutic potential of JB for the treatment of CRC.