An Investigation into the Impact of a Glutaminase Inhibitor, Compound 968, on Nrf2 Signaling

Glutaminase is a critical enzyme that catalyzes the process of glutaminolysis for energy synthesis. Meanwhile, glutaminase also contributes to the pathological process of various diseases, such as cancer, neurodegenerative diseases, and inflammation. This leads to the discovery of glutaminase inhibitors for therapeutical uses. However, the mechanisms of the beneficial therapeutical effect of glutaminase inhibitors are still unclear. This pilot study aimed to determine the impact of a well-characterized glutaminase inhibitor, compound 968 (C968), on Nrf2 signaling. We performed molecular docking, luciferase assay, and quantitative PCR to determine the activation of Nrf2 and the expression of several Nrf2-related genes. These experiments found that C968 induced the Nrf2 activation and promoted the expression of Nrf2, heme oxygenase-1 (HO-1), and NAD(P)H Quinone Dehydrogenase-1 (NQO-1). All findings provide evidence that Nrf2 activation could be one of the mechanisms contributing to the therapeutical activity of C968, but more studies are warranted to further confirm this mechanism.

Astragalus membranaceus Alters Rumen Bacteria to Enhance Fiber Digestion, Improves Antioxidant Capacity and Immunity Indices of Small Intestinal Mucosa, and Enhances Liver Metabolites for Energy Synthesis in Tibetan Sheep

Natural, non-toxic feed additives can potentially replace chemical medications and antibiotics that are offered sheep to improve performance. In the present study, Tibetan sheep were supplemented with the root of Astragalus membranaceus (AMT), a traditional herb used widely in China. Twenty-four male Tibetan sheep (31 ± 1.4 kg; 9-month-old) were assigned randomly to one of four levels of supplementary AMT: 0 g/kg (A0), 20 g/kg (A20), 50 g/kg (A50) and 80 g/kg (A80) dry matter intake (DMI). The A50 and A80 groups increased the diversity of rumen bacteria on d 14 and the relative abundances of fiber decomposing bacteria. Supplementary AMT upregulated the metabolism of vitamins, nucleotides, amino acids and glycan, and downregulated the metabolism of lipids and carbohydrates. In addition, supplementary AMT enriched rumen bacteria for drug resistance, and reduced bacteria incurring cell motility. In general, AMT supplementation increased the concentrations of catalase (CAT), superoxide dismutase (SOD) total antioxidant capacity (T-AOC) and secretory immunoglobulin A (sIgA) in the small intestinal mucosa and CAT and SOD in meat tissue. The liver tissue metabolome response showed that AMT in the A80 lambs compared to the A0 lambs upregulated the metabolites for energy synthesis. It was concluded that supplementary A. membranaceus increased the relative abundances of fiber decomposing bacteria and improved the antioxidant capacities and immunity indices of small intestinal mucosa and meat tissue in Tibetan sheep.

The features of metabolism and structural organization of dental system under conditions of experimental insulin resistance

Peculiarities of calcium homeostasis, the activity of energy synthesis enzymes and structural organization of the dental system in rats under conditions of insulin resistance were analyzed. It was found that impaired glucose tolerance is manifested by a decreased mineralizing ability of hard tissues of alveolar processes and teeth, accompanied by a decrease in calcium content in erythrocyte mass and alveolar processes and an increase in acid phosphatase activity in blood serum. In rats with insulin resistance a decrease in the activity of lactate- and succinate dehydrogenase was detected. Degenerative changes were observed in the bone thickness of the dental area of insulin resistant rats, which were accompanied by the development of hypercellularity of the osteogenic layer of periosteum. Reactive changes in the tooth pulp were manifested by a decrease in the area of its loose connective tissue. Hyperplastic changes with the formation of unexpressed acanthotic bands developed in the oral mucosa of experimental animals, the thickness of the basal and granular layers increased against the background of a decrease in the prickle layer of epitheliocytes. In experimental group we observed a decrease in the nuclear cytoplasmic index and an increase in keratin formation in the epithelium. A narrowing of the lumen of capillaries and arterioles of the dental area, hyperplasia of endothelial cells and an increased accumulation of glycoproteins, especially in small arteries, were also detected in experimental group. Thus, altered carbohydrate metabolism leads to the metabolic changes of teeth supporting apparatus and oral mucosa, aggravating the course of insulin resistance with the development of dental system pathology.

Morphological observation and protein expression of fertile and abortive ovules in Castanea mollissima

Chinese chestnuts (Castanea mollissima Blume.) contain 12–18 ovules in one ovary, but only one ovule develops into a seed, indicating a high ovule abortion rate. In this study, the Chinese chestnut ‘Huaihuang’ was used to explore the possible mechanisms of ovule abortion with respect to morphology and proteomics. The morphology and microstructure of abortive ovules were found to be considerably different from those of fertile ovules at 20 days after anthesis (20 DAA). The fertile ovules had completely formed tissues, such as the embryo sac, embryo and endosperm. By contrast, in the abortive ovules, there were no embryo sacs, and wide spaces between the integuments were observed, with few nucelli. Fluorescence labelling of the nuclei and transmission electron microscopy (TEM) observations showed that cells of abortive ovules were abnormally shaped and had thickened cell walls, folded cell membranes, condensed cytoplasm, ruptured nuclear membranes, degraded nucleoli and reduced mitochondria. The iTRAQ (isobaric tag for relative and absolute quantitation) results showed that in the abortive ovules, low levels of soluble protein with small molecular weights were found, and most of differently expressed proteins (DEPs) were related to protein synthesis, accumulation of active oxygen free radical, energy synthesis and so on. These DEPs might be associated with abnormal ovules formation.

The Changes of Prooxidant-Antioxidant and Energy Homeostasis in Rates with Impaired Glucose Tolerance

Topicality.Violation of glucose utilization leads to disruption of all types of metabolic processes. Particularly dangerous in the prognostic aspect is the combination of carbohydrate metabolism disorders and other endocrine pathologies, in particular hypothyroid dysfunction. The objective of the study was to examine prooxidant-antioxidant changes ofblood serum, teeth pulp and oral mucosa in rats with impaired glucose tolerance on the background of iodine deficiency. Materials and Methods. The studies were carried on 60 female rats, which were divided into two research groups - rats with impaired glucose tolerance and insulin resistance on the background of iodine deficiency. Lipid peroxidation processes were evaluated due to the content of diene conjugates and active products that react with thiobarbituric acid in blood serum, teeth pulp and oral mucosa. Antioxidant defence of blood serum was characterized by catalase, ceruloplasmin, superoxide dismutase, glutathione peroxidase, glutathione reductase activity and iron transferrin saturation. Energy metabolism was examined by the activity of succinate dehydrogenase, malate dehydrogenase and lactate dehydrogenase in blood serum. Results.Impaired glucose tolerance was foundto lead to the activation of lipoperoxidation, mainly due to the accumulation of final products of lipid peroxidation in all studied tissues against the background of redistribution of the activity of antiradical enzymes. Under these experimental conditions, different changes in the activity of energy synthesis enzymes were observed. The development of combined endocrine pathology has led to more pronounced changes in the prooxidant-antioxidant system and significant suppression of serum dehydrogenase activity. Conclusions.The development of insulin resistance on the background of iodine deficiency causes the activation of oxygen-dependent processes in periodontal tissues against the background of reduced antiradical defence and disruption of energy synthesis system.

The mitochondrial calcium uniporter compensates for Complex I dysfunction

Calcium (Ca2+) entering mitochondria potently stimulates ATP synthesis. Increases in Ca2+ preserve energy synthesis in cardiomyopathies caused by mitochondrial dysfunction, and occur due to enhanced activity of the mitochondrial Ca2+ uniporter channel. The signaling mechanism that mediates this compensatory increase remains unknown. Here, we find that increases in the uniporter are due to impairment in Complex I of the electron transport chain (ETC). In normal physiology, Complex I promotes uniporter degradation via an interaction with the uniporter pore-forming subunit, a process we term Complex I-induced protein turnover (CLIPT). When Complex I dysfunction ensues, contact with the uniporter is inhibited, preventing degradation, and leading to a build-up in functional channels. Preventing uniporter activity leads to early demise in Complex I-deficient animals. Conversely, enhancing uniporter stability rescues survival and function in Complex I deficiency. Taken together, our data identify a fundamental pathway producing compensatory increases in Ca2+ influx during Complex I impairment.

Antimicrobial Activity and Proposed Action Mechanism of Linalool Against Pseudomonas fluorescens

In this study, linalool, one of the principal components of essential oils, was used as an antibacterial agent to investigate the antibacterial activity and mechanism of linalool against Pseudomonas fluorescens. The reduction in membrane potential (MP), leakage of alkaline phosphatase (AKP) and the release of macromolecules, including DNA, RNA and protein confirmed that damage to cell wall membrane structure and leakage of cytoplasmic contents were due to the linalool treatment. Furthermore, the decrease of enzyme activity, including the succinate dehydrogenase (SDH), malate dehydrogenase (MDH), pyruvate kinase (PK), and ATPase indicated that linalool could lead to metabolic dysfunction and inhibit energy synthesis. In addition, the activity of respiratory chain dehydrogenase and metabolic activity of respiration indicated that linalool inhibits cellular respiration. These results revealed that linalool had strong antibacterial activity against P. fluorescens via membrane damage, bacterial metabolic and oxidative respiratory perturbations, interfering in cellular functions and even causing cell death. It was suggested that linalool may be a new potential source as food antiseptics in food systems.

Structural and Biochemical Characterization of EFhd1/Swiprosin-2, an Actin-Binding Protein in Mitochondria

Ca2+ regulates several cellular functions, including signaling events, energy production, and cell survival. These cellular processes are mediated by Ca2+-binding proteins, such as EF-hand superfamily proteins. Among the EF-hand superfamily proteins, allograft inflammatory factor-1 (AIF-1) and swiprosin-1/EF-hand domain-containing protein 2 (EFhd2) are cytosolic actin-binding proteins. AIF-1 modulates the cytoskeleton and increases the migration of immune cells. EFhd2 is also a cytoskeletal protein implicated in immune cell activation and brain cell functions. EFhd1, a mitochondrial fraternal twin of EFhd2, mediates neuronal and pro-/pre-B cell differentiation and mitoflash activation. Although EFhd1 is important for maintaining mitochondrial morphology and energy synthesis, its mechanism of action remains unclear. Here, we report the crystal structure of the EFhd1 core domain comprising a C-terminus of a proline-rich region, two EF-hand domains, and a ligand mimic helix. Structural comparisons of EFhd1, EFhd2, and AIF-1 revealed similarities in their overall structures. In the structure of the EFhd1 core domain, two Zn2+ ions were observed at the interface of the crystal contact, suggesting the possibility of Zn2+-mediated multimerization. In addition, we found that EFhd1 has Ca2+-independent β-actin-binding and Ca2+-dependent β-actin-bundling activities. These findings suggest that EFhd1, an actin-binding and -bundling protein in the mitochondria, may contribute to the Ca2+-dependent regulation of mitochondrial morphology and energy synthesis.

LIPID METABOLISM DYNAMICS IN TEST-SUBJECTS OF A 5-DAY DRY IMMERSION EXPERIMENT

Blood samples from six 25–40 y.o. male subjects in a 5-d dry immersion (DI) experiment were analyzed for cholesterol, cholesterol of high- (HDLP), low- (LDLP) and very low density lipoproteins, triglycerides, apolipoproteins А1 (аpoА1) and apolipoproteins В (аpоВ), non-esterified (free) fatty acids (NEFA), β-hydroxibutyrate and phospholipids. Atherogenic indices were calculated, as well as the ratios of cholesterol, аpоВ/аpоА1 and cholesterol/phospholipids. No significant changes in cholesterol or lipoprotein fractions were determined. Increases in the triglyceride level and apoB/apoA1 ratio as harbingers of incipient atherogenesis showed up on the final day in DI and disappeared two days later. The process of readaptation to normal conditions is accompanied by the development of a stress reaction characterized by increased use of lipid substrates (phospholipids, β-hydroxybutyrate, NEFA) for energy synthesis.