Lysozyme Improves the Inhibitory Effects of Panax notoginseng Saponins on Phenotype Transformation of Vascular Smooth Muscle Cells by Binding to Ginsenoside Re

Panax notoginseng saponins (PNS) have been used to treat cardiovascular diseases for hundreds of years in China. Lysozyme can bind to exogenous compounds and promote their activity. Nevertheless, knowledge of whether there is a synergistic role between lysozyme and PNS is far from sufficient. In this study, we show that the mixture of PNS and lysozyme synergistically inhibited platelet derived growth factor BB (PDGF-BB)-induced vascular smooth muscle cell (VSMC) viability, and in the five main components of PNS, GS-Re, but not GS-Rb1, NG-R1, GS-Rg1, or GS-Rd, reduced VSMC viability by combined application with lysozyme. Next, the supramolecular complexes formed by GS-Re and lysozyme were detected by mass spectrometry, and the binding ability increased with the concentration ratio of GS-Re to lysozyme from 4:1 to 12:1. In the supramolecular complexes, the relative contents of α-helix of lysozyme were increased, which was beneficial for stabilizing the structure of lysozyme. The 12:1 mixture of GS-Re and lysozyme (12.8 μmol/L GS-Re+1.067 μmol/L lysozyme) repressed PDGF-BB-induced VSMC viability, proliferation, and migration, which were associated with the upregulated differentiated markers and downregulated dedifferentiated markers. Finally, in CaCl2-induced rodent abdominal aortic aneurysm (AAA) models, we found that the 12:1 mixture of GS-Re and lysozyme slowed down AAA progression and reversed phenotype transformation of VSMCs. Thus, Gs-Re combined with a small amount of lysozyme may provide a novel therapeutic strategy for vascular remodeling-associated cardiovascular diseases.

An integrated host-microbiome response to atrazine exposure mediates toxicity in Drosophila

The gut microbiome produces vitamins, nutrients, and neurotransmitters, and helps to modulate the host immune system—and also plays a major role in the metabolism of many exogenous compounds, including drugs and chemical toxicants. However, the extent to which specific microbial species or communities modulate hazard upon exposure to chemicals remains largely opaque. Focusing on the effects of collateral dietary exposure to the widely used herbicide atrazine, we applied integrated omics and phenotypic screening to assess the role of the gut microbiome in modulating host resilience in Drosophila melanogaster. Transcriptional and metabolic responses to these compounds are sex-specific and depend strongly on the presence of the commensal microbiome. Sequencing the genomes of all abundant microbes in the fly gut revealed an enzymatic pathway responsible for atrazine detoxification unique to Acetobacter tropicalis. We find that Acetobacter tropicalis alone, in gnotobiotic animals, is sufficient to rescue increased atrazine toxicity to wild-type, conventionally reared levels. This work points toward the derivation of biotic strategies to improve host resilience to environmental chemical exposures, and illustrates the power of integrative omics to identify pathways responsible for adverse health outcomes.

Epigenetic Mechanisms of Endocrine-Disrupting Chemicals in Obesity

The incidence of obesity has dramatically increased over the last decades. Recently, there has been a growing interest in the possible association between the pandemics of obesity and some endocrine-disrupting chemicals (EDCs), termed “obesogens”. These are a heterogeneous group of exogenous compounds that can interfere in the endocrine regulation of energy metabolism and adipose tissue structure. Oral intake, inhalation, and dermal absorption represent the major sources of human exposure to these EDCs. Recently, epigenetic changes such as the methylation of cytosine residues on DNA, post-translational modification of histones, and microRNA expression have been considered to act as an intermediary between deleterious effects of EDCs and obesity development in susceptible individuals. Specifically, EDCs exposure during early-life development can detrimentally affect individuals via inducing epigenetic modifications that can permanently change the epigenome in the germline, enabling changes to be transmitted to the next generations and predisposing them to a multitude of diseases. The purpose of this review is to analyze the epigenetic alterations putatively induced by chemical exposures and their ability to interfere with the control of energy metabolism and adipose tissue regulation, resulting in imbalances in the control of body weight, which can lead to obesity.

Autoinhibition and regulation by phosphoinositides of ATP8B1, a human lipid flippase associated with intrahepatic cholestatic disorders

P-type ATPases from the P4 subfamily (P4-ATPases) are primary active transporters that maintain lipid asymmetry in eukaryotic cell membranes by flipping lipids from the exoplasmic to the cytosolic leaflet. Mutations in several human P4-ATPase genes are associated with severe diseases. For instance, mutations in the ATP8B1 gene result in progressive familial intrahepatic cholestasis, a rare inherited disorder that usually progresses toward liver failure. ATP8B1 forms a binary complex with CDC50A and displays a broad specificity to glycerophospholipids, but regulatory mechanisms are unknown. Here, we report the cryo-EM structure of the human lipid flippase ATP8B1-CDC50A at 3.1 angstrom resolution. The lipid flippase complex is autoinhibited by the N- and C-termini of ATP8B1, which in concert form extensive interactions with the catalytic sites and flexible domain interfaces of ATP8B1. Consistently, ATP hydrolysis by the ATP8B1-CDC50A complex requires truncation of its C-terminus as well as the presence of phosphoinositides, with a marked preference for phosphatidylinositol-3,4,5-phosphate (PI(3,4,5)P3), and removal of both N- and C-termini results in full activation. Restored inhibition of ATP8B1 truncation constructs with a synthetic peptide mimicking the C-terminus further suggests molecular communication between N- and C-termini in the autoinhibition process and demonstrates that the regulatory mechanism can be interfered with by exogenous compounds. A conserved (G/A)(Y/F)AFS motif in the C-termini of several P4-ATPase subfamilies suggests that this mechanism is employed widely across P4-ATPase lipid flippases, including both plasma membrane and endomembrane P4-ATPases.

Cardiac Troponins Metabolism: From Biochemical Mechanisms to Clinical Practice (Literature Review)

The metabolic processes of endo- and exogenous compounds play an important role in diagnosing and treating patients since many metabolites are laboratory biomarkers and/or targets for therapeutic agents. Cardiac troponins are one of the most critical biomarkers to diagnose cardiovascular diseases, including acute myocardial infarction. The study of troponin metabolism is of great interest as it opens up new possibilities for optimizing laboratory diagnostics. This article discusses in detail the key stages of the cardiac troponins metabolism, in particular the mechanisms of release from a healthy myocardium, mechanisms of circulation in the bloodstream, possible mechanisms of troponin penetration into other biological fluids (oral fluid, cerebrospinal fluid, pericardial and amniotic fluids), mechanisms of elimination of cardiac troponins from the blood, and daily changes in the levels of troponins in the blood. Considering these aspects of cardiac troponin metabolism, attention is focused on the potential value for clinical practice.

Chlorothalonil induces the intestinal epithelial barrier dysfunction in Caco-2 cell-based in vitro monolayer model by activating MAPK pathway

The widespread use of chlorothalonil (CTL) has caused environmental residues and food contamination. Although the intestinal epithelial barrier (IEB) is directly involved in the metabolism and transportation of various exogenous compounds, there are few studies on the toxic effects of these compounds on the structure and function of IEB. The disassembly of tight junction (TJ) is a major cause of intestinal barrier dysfunction under exogenous compounds intake, but the precise mechanisms are not well understood. Here, we used Caco-2 cell monolayers as an in vitro model of human IEB to evaluate the toxicity of CTL exposure on the structure and function of IEB. Results showed that CTL exposure increased the paracellular permeability of the monolayers and downregulated messenger RNA levels of the TJ genes (ZO-1, OCLN, and CLDN1), polarity marker gene (SI), and anti-apoptosis gene (BCL-2) but upregulated the messenger RNA levels of apoptosis-related genes, including BAD, BAX, CASP3, and CASP8. Western blot analysis and immunofluorescence assay results showed the decreased levels and disrupted distribution of TJ protein network, including ZO-1 and CLDN1 in CTL-exposed IEB. In addition, the accumulation of intracellular reactive oxygen species, decreased mitochondrial membrane potential, and increased active CASP3 expression were observed in treated IEB. The result of TUNEL assay further confirmed the occurrence of cell apoptosis after CTL exposure. In addition, the phosphorylation of mitogen-activated protein kinases, including ERK, JNK and p38, was increased in CTL-exposed IEB. In summary, our results demonstrated that CTL exposure induced IEB dysfunction in Caco-2 cell monolayers by activating the mitogen-activated protein kinase pathway.

Serum Albumin: A Multifaced Enzyme

Human serum albumin (HSA) is the most abundant protein in plasma, contributing actively to oncotic pressure maintenance and fluid distribution between body compartments. HSA acts as the main carrier of fatty acids, recognizes metal ions, affects pharmacokinetics of many drugs, provides the metabolic modification of some ligands, renders potential toxins harmless, accounts for most of the anti-oxidant capacity of human plasma, and displays esterase, enolase, glucuronidase, and peroxidase (pseudo)-enzymatic activities. HSA-based catalysis is physiologically relevant, affecting the metabolism of endogenous and exogenous compounds including proteins, lipids, cholesterol, reactive oxygen species (ROS), and drugs. Catalytic properties of HSA are modulated by allosteric effectors, competitive inhibitors, chemical modifications, pathological conditions, and aging. HSA displays anti-oxidant properties and is critical for plasma detoxification from toxic agents and for pro-drugs activation. The enzymatic properties of HSA can be also exploited by chemical industries as a scaffold to produce libraries of catalysts with improved proficiency and stereoselectivity for water decontamination from poisonous agents and environmental contaminants, in the so called “green chemistry” field. Here, an overview of the intrinsic and metal dependent (pseudo-)enzymatic properties of HSA is reported to highlight the roles played by this multifaced protein.

The Functions of Cytochrome P450 ω-hydroxylases and the Associated Eicosanoids in Inflammation-Related Diseases

The cytochrome P450 (CYP) ω-hydroxylases are a subfamily of CYP enzymes. While CYPs are the main metabolic enzymes that mediate the oxidation reactions of many endogenous and exogenous compounds in the human body, CYP ω-hydroxylases mediate the metabolism of multiple fatty acids and their metabolites via the addition of a hydroxyl group to the ω- or (ω-1)-C atom of the substrates. The substrates of CYP ω-hydroxylases include but not limited to arachidonic acid, docosahexaenoic acid, eicosapentaenoic acid, epoxyeicosatrienoic acids, leukotrienes, and prostaglandins. The CYP ω-hydroxylases-mediated metabolites, such as 20-hyroxyleicosatrienoic acid (20-HETE), 19-HETE, 20-hydroxyl leukotriene B4 (20-OH-LTB4), and many ω-hydroxylated prostaglandins, have pleiotropic effects in inflammation and many inflammation-associated diseases. Here we reviewed the classification, tissue distribution of CYP ω-hydroxylases and the role of their hydroxylated metabolites in inflammation-associated diseases. We described up-regulation of CYP ω-hydroxylases may be a pathogenic mechanism of many inflammation-associated diseases and thus CYP ω-hydroxylases may be a therapeutic target for these diseases. CYP ω-hydroxylases-mediated eicosanods play important roles in inflammation as pro-inflammatory or anti-inflammatory mediators, participating in the process stimulated by cytokines and/or the process stimulating the production of multiple cytokines. However, most previous studies focused on 20-HETE,and further studies are needed for the function and mechanisms of other CYP ω-hydroxylases-mediated eicosanoids. We believe that our studies of CYP ω-hydroxylases and their associated eicosanoids will advance the translational and clinal use of CYP ω-hydroxylases inhibitors and activators in many diseases.

Identification and Characterization of an Antennae-Specific Glutathione S-Transferase From the Indian Meal Moth

Insect glutathione-S-transferases (GSTs) play essential roles in metabolizing endogenous and exogenous compounds. GSTs that are uniquely expressed in antennae are assumed to function as scavengers of pheromones and host volatiles in the odorant detection system. Based on this assumption, antennae-specific GSTs have been identified and functionally characterized in increasing number of insect species. In the present study, 17 putative GSTs were identified from the antennal transcriptomic dataset of the Indian meal moth, Plodia interpunctella, a severe stored-grain pest worldwide. Among the GSTs, only PiGSTd1 is antennae-specific according to both Fragments Per Kilobase Million (FPKM) and quantitative real-time PCR (qRT-PCR) analysis. Sequence analysis revealed that PiGSTd1 has a similar identity as many delta GSTs from other moths. Enzyme kinetic assays using 1-chloro-2,4-dinitrobenzene (CDNB) as substrates showed that the recombinant PiGSTd1 gave a Km of 0.2292 ± 0.01805 mM and a Vmax of 14.02 ± 0.2545 μmol·mg−1·min−1 under the optimal catalytic conditions (35°C and pH = 7.5). Further analysis revealed that the recombinant PiGSTd1 could efficiently degrade the sex pheromone component Z9-12:Ac (75.63 ± 5.52%), as well as aldehyde volatiles, including hexanal (89.10 ± 2.21%), heptanal (63.19 ± 5.36%), (E)-2-octenal (73.58 ± 3.92%), (E)-2-nonenal (75.81 ± 1.90%), and (E)-2-decenal (61.13 ± 5.24%). Taken together, our findings suggest that PiGSTd1 may play essential roles in degrading and inactivating a variety of odorants, especially sex pheromones and host volatiles of P. interpunctella.