Succinate Dehydrogenase Activity Research Articles

Neuroglobin Facilitates Neuronal Oxygenation through Tropic Migration under Hypoxia or Anemia in Rat: How Does the Brain Breathe?

The discovery of neuroglobin (Ngb), a brain- or neuron-specific member of the hemoglobin family, has revolutionized our understanding of brain oxygen metabolism. Currently, how Ngb plays such a role remains far from clear. Here, we report a novel mechanism by which Ngb might facilitate neuronal oxygenation upon hypoxia or anemia. We found that Ngb was present in, co-localized to, and co-migrated with mitochondria in the cell body and neurites of neurons. Hypoxia induced a sudden and prominent migration of Ngb towards the cytoplasmic membrane (CM) or cell surface in living neurons, and this was accompanied by the mitochondria. In vivo, hypotonic and anemic hypoxia induced a reversible Ngb migration toward the CM in cerebral cortical neurons in rat brains but did not alter the expression level of Ngb or its cytoplasm/mitochondria ratio. Knock-down of Ngb by RNA interference significantly diminished respiratory succinate dehydrogenase (SDH) and ATPase activity in neuronal N2a cells. Over-expression of Ngb enhanced SDH activity in N2a cells upon hypoxia. Mutation of Ngb at its oxygen-binding site (His64) significantly increased SDH activity and reduced ATPase activity in N2a cells. Taken together, Ngb was physically and functionally linked to mitochondria. In response to an insufficient oxygen supply, Ngb migrated towards the source of oxygen to facilitate neuronal oxygenation. This novel mechanism of neuronal respiration provides new insights into the understanding and treatment of neurological diseases such as stroke and Alzheimer's disease and diseases that cause hypoxia in the brain such as anemia.

Study of histochemical characterizations of skeletal muscle fiber types in the rabbits ( Oryctolagus Cuniculus )

This project has been conducted on New Zealand White Rabbits (newborns and adults) . Biceps brachii, soleus and abdominal wall of muscles were used in this study. Fresh pieces of muscle tissues were frozen to be cut at (10 μm) thick sections by the cryostat.Skeletal musclefibre types were investigated histochemically to demonstrate myosin adenosin triphosphatase (ATPase) activity using acid and alkaline preincubation and succinate dehydrogenase ( SDHase ) activity . In this way it may be possible to recognize the fast and slow twitch muscle fibers, as well as to explore the difference in reaching maturity between different muscles of the body. The results showed that, the biceps brachii and abdominal wall muscles consist predominantly of fast fibers, whilst the soleus muscle is made up of a near homogenous population of slow fibers. The immature abdominal wall muscle showed some reversal of the mature limb muscles staining pattern of the same animal.

Arbuscular mycorrhiza fungus alleviates arsenic mediated disturbances in tricarboxylic acid cycle and nitrogen metabolism in Triticum aestivum L.

Utilization of arbuscular mycorrhizal (AM) fungi (AMF) as a sustainable strategy in redeeming arsenic (As) toxicity in plants is a promising approach. Low As accumulation, restoration of physiological processes, and As tolerance by AMF have been documented in crop plants. However, to comprehend AM-mediated As tolerance in plants, understanding the biochemical responses of host to the symbiont is crucial. The study evaluated the effect of an AM fungus, Rhizophagus intraradices on tricarboxylic acid cycle (TCA) and nitrogen metabolism of Triticum aestivum under three As concentrations (0, 25, and 50 mg As kg−1 soil). Results showed that TCA cycle and nitrogen metabolism were severely impaired by As that resulted into a higher C/N ratio. However, colonization by R. intraradices attenuated As mediated alterations in TCA cycle by augmenting the activity of pyruvate dehydrogenase that provided sufficient substrate for the TCA cycle. Furthermore, mycorrhizal (M) plants reinstated the activities of isocitrate dehydrogenase, succinate dehydrogenase, fumarase, and malate dehydrogenase even under high As level. Although citrate synthase and oxoglutarate dehydrogenase activities declined upon As exposure in M-plants, these were nevertheless higher than their non-mycorrhizal (NM) counterparts, ensuring higher levels of citric acid and succinic acid in M-plants. AM colonization also moderated the As-mediated disturbances in nitrogen assimilation by augmenting the activity of nitrate reductase, nitrite reductase, glutamine synthase, and glutamine-2-oxoglutarate amino transferase. Overall findings of the study point out that colonization by R. intraradices favourably regulated the TCA cycle and nitrogen metabolism and confronted As-mediated alterations in C/N ratio.

Antioxidant Status and Biotechnological Potential of New Vischeria vischeri (Eustigmatophyceae) Soil Strains in Enrichment Cultures.

The functional state of enrichment cultures of the Eustigmatophycean strains Vischeria vischeri MZ-E3 and MZ-E4 after 25-day cultivation in the BBM medium was studied. The concentrations of chlorophyll a, total carotenoids, protein, vitamins A and E, fatty acid peroxidation product content, an antioxidant enzyme, and succinate dehydrogenase activity were measured. MZ-E3 succinate dehydrogenase activity was significantly higher by 2.21 times; the MZ-E4 strain had 2.94 times higher glutathione peroxidase activity. The MZ-E3 antioxidant activity index and the MZ-E3 unsaturation of fatty acids were 1.3 and 1.25 times higher than the MZ-E4. The retinol and α-tocopherol content of the MZ-E3 was 28.6% and 38.76% higher than MZ-E4. The main fatty acid profile differences were the 3.46-fold and 3.92-fold higher stearic and eicosapentaenoic acid content in the MZ-E4 biomass. MZ-E3 had higher antioxidant, energy, and metabolic and photosynthetic status than MZ-E4. The antioxidant status of the studied strains showed the dependence of the adaptive mechanisms of each, associated with differences in the ecological conditions of the biotopes from which they were isolated. These strains are promising for producing α-tocopherol and biomass enriched with omega-3 and omega-6 fatty acids.

Sulfite Impairs Bioenergetics and Redox Status in Neonatal Rat Brain: Insights into the Early Neuropathophysiology of Isolated Sulfite Oxidase and Molybdenum Cofactor Deficiencies.

Isolated sulfite oxidase (ISOD) and molybdenum cofactor (MoCD) deficiencies are genetic diseases biochemically characterized by the toxic accumulation of sulfite in the tissues of patients, including the brain. Neurological dysfunction and brain abnormalities are commonly observed soon after birth, and some patients also have neuropathological alterations in the prenatal period (in utero). Thus, we investigated the effects of sulfite on redox and mitochondrial homeostasis, as well as signaling proteins in the cerebral cortex of rat pups. One-day-old Wistar rats received an intracerebroventricular administration of sulfite (0.5µmol/g) or vehicle and were euthanized 30min after injection. Sulfite administration decreased glutathione levels and glutathione S-transferase activity, and increased heme oxygenase-1 content in vivo in the cerebral cortex. Sulfite also reduced the activities of succinate dehydrogenase, creatine kinase, and respiratory chain complexes II and II-III. Furthermore, sulfite increased the cortical content of ERK1/2 and p38. These findings suggest that redox imbalance and bioenergetic impairment induced by sulfite in the brain are pathomechanisms that may contribute to the neuropathology of newborns with ISOD and MoCD. Sulfite disturbs antioxidant defenses, bioenergetics, and signaling pathways in the cerebral cortex of neonatal rats. CII: complex II; CII-III: complex II-III; CK: creatine kinase; GST: glutathione S-transferase; HO-1: heme oxygenase-1; SDH: succinate dehydrogenase; SO32-: sulfite.

Features of the Influence of the Autonomic Nervous System on the Regulatory and Metabolic Parameters of Lymphocytes in Healthy Children and Children with Special Health Abilities

The aim of the study was to study the content of biogenic monoamines (catecholamins and serotonin) and metabolic parameters (activities of succinate dehydrogenase and acid phosphatase) of lymphocytes in normal children and in children with special health abilities, depending on the type of autonomic regulation. The survey involved 168 children of primary school age, of these, 114 relatively healthy children and 54 children with intellectual disabilities (mild (F70) and moderate (F71) degree of mental retardation). The groups were comparable in terms of gender and age. In both studied groups, an increase in the parameters of succinate dehydrogenase and catecholamines from vagotonic to hypersympathicotonic types of the initial vegetative tone was recorded. Also, in the group of children with special health abilities, a decrease in the activity of acid phosphatase was found as the activity of the sympathetic division of the autonomic nervous system increased. In general, in healthy children, against the background of the prevailing eutonic type of autonomic regulation, the optimal regulatory and metabolic parameters of the cell are fixed, which determines sufficient adaptive responses in this group. In the group of children with disabilities, the dominant activity of the sympathetic division of the autonomic nervous system manifests itself at the cellular level as hypercatecholaminemia, reduced levels of serotonin and acid phosphatase activity.

Abstract P3-11-11: Impaired Succinate Metabolism Supports Endocrine Therapy Resistance in ER Positive Breast Cancers

Abstract Estrogen receptor positive (ER+) breast cancer is the most common subtype among all breast cancers and is responsible for most breast cancer related deaths. Endocrine therapies, such as selective estrogen receptor modulators (SERM) and aromatase inhibitors (AI), often given in combination with cyclin-dependent kinase 4/6 (CDK4/6) inhibitors, are initially effective but the majority of advanced ER+ breast cancers eventually become refractory to endocrine therapies. Therefore, understanding the underlying molecular mechanisms that enable or promote resistance to endocrine therapies may lead to novel therapeutic targets. Cancer cells consume greater quantities of glucose to meet their energy and anabolic demands to support cell growth and proliferation. In this study, we used breast cancer cell models that are endocrine therapy sensitive and resistant and investigated the metabolites by growing the cells in the presence of the stable glucose isotope, UC13-Glucose. We measured the C13-labelled metabolites of glycolysis and the TCA cycle. Glucose consumption was higher in endocrine therapy resistant MCF7/LCC9 (LCC9) cells compared with parental MCF7 (MCF7) and estrogen independent, endocrine therapy sensitive MCF7/LCC1 (LCC1) cells. Notably, in LCC9 cells the m+4 and m+6 isotopomer of C-13 labelled citrate was absent with a concurrent high succinate:fumarate ratio. Furthermore, in LCC9 cells, most of the fumarate was unlabeled suggesting that fumarate was not generated from glucose. These results suggest that the TCA cycle is impaired in LCC9 cells and the conversion of succinate to fumarate is dysregulated. Succinate dehydrogenase (SDH) enzyme is responsible for reversible catalytic conversion of succinate to fumarate. SDH is a multimeric protein comprised of four different subunits and SDH assembly factor 2 (SDHAF2), which is a tumor suppressor gene. Comparable SDH enzyme activity was observed in LCC9 and LCC1 cells. Intriguingly, when SDH activity was inhibited using dimethylmalonate, the LCC9 cells were re-sensitized to both Fulvestrant and 4-hydroxytamoxifen. Succinate accumulation was accompanied with HIF 1-alpha stabilization and SDH inhibition led to lower levels of HIF1-alpha. This indicated that SDH may function in the conversion of fumarate to succinate in LCC9 cells. Our study further investigates the source of fumarate in LCC9 cells. Overall, this study suggests that targeting succinate metabolism may help to restore sensitivity to Fulvestrant and tamoxifen in endocrine therapy resistance in ER+ breast cancer cells. Citation Format: Anil Yadav, Karla Andrade de Oliveira, Lu Jin, Robert Clarke, Surojeet Sengupta. Impaired Succinate Metabolism Supports Endocrine Therapy Resistance in ER Positive Breast Cancers [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P3-11-11.

Effects of Probiotics Supplementation on the Intestinal Metabolites, Muscle Fiber Properties, and Meat Quality of Sunit Lamb.

The development of animal husbandry is closely related to the meat quality of small ruminants. Intestinal metabolites and the muscle fiber types of lambs are important factors that affect their meat quality, but few studies have examined the regulation of the "intestinal muscle axis" by probiotics. In this study, 12 Sunit lambs were divided into a control group (C) and a probiotics group (P). The gene expressions of the myosin heavy chain, metabolic enzyme activity, and short-chain fatty acids in the intestines were analyzed using gas chromatography-mass spectrometry (GC-MS) and quantitative real-time PCR. The results showed that levels of propionic acid and butyric acid in the intestines of group P were significantly higher than in group C (p < 0.05). In addition, probiotics increased the number and area ratio of type I muscle fibers. They also increased the mRNA expression of MyHC IIA and the activity of malate dehydrogenase (MDH) and succinate dehydrogenase (SDH). Propionic acid was negatively correlated with the number ratio of type IIB muscle fibers. Butyric acid was found to be significantly positively correlated with the number ratio of type IIA muscle fibers. Cooking loss, pH24h, and shear force decreased significantly in group P. In conclusion, intestinal metabolites (SCFAs) altered the activity of oxidative-myofibril-metabolizing enzymes and the expression of myosin heavy-chain type IIA, reduced the meat shear values, and improved meat tenderness. This study provides a new basis for improving the production and meat quality of small ruminants.

Inhibition of Succinate Dehydrogenase by Pesticides (SDHIs) and Energy Metabolism.

Succinate dehydrogenase (SDH) is one of the enzymes of the tricarboxylic acid cycle (Krebs cycle) and complex II of the mitochondrial respiratory chain. A class of fungicides (SDHIs) targets the complex II reaction in the SDH. A large number of those in use have been shown to inhibit SDH in other phyla, including humans. This raises questions about possible effects on human health and non-target organisms in the environment. The present document will address metabolic consequences in mammals; it is neither a review on SDH nor is it about the toxicology of SDHIs. Most clinically relevant observations are linked to a severe decrease in SDH activity. Here we shall examine the mechanisms for compensating a loss of SDH activity and their possible weaknesses or adverse consequences. It can be expected that a mild inhibition of SDH will be compensated by the kinetic properties of this enzyme, but this implies a proportionate increase in succinate concentration. This would be relevant for succinate signaling and epigenetics (not reviewed here). With regard to metabolism, exposure of the liver to SDHIs would increase the risk for non-alcoholic fatty liver disease (NAFLD). Higher levels of inhibition may be compensated by modification of metabolic fluxes with net production of succinate. SDHIs are much more soluble in lipids than in water; consequently, a different diet composition between laboratory animals and humans is expected to influence their absorption.

Antibacterial Activity and Mechanism of Madecassic Acid against Staphylococcus aureus.

Antibacterial resistance has become one of the most serious problems threating global health. To overcome this urgent problem, many scientists have paid great attention to developing new antibacterial drugs from natural products. Hence, for exploring new antibacterial drugs from Chinese medicine, a series of experiments were carried out for verifying and elucidating the antibacterial activity and mechanisms of madecassic acid (MA), which is an active triterpenoid compound isolated from the traditional Chinese medicine, Centella asiatica. The antibacterial activity was investigated through measuring the diameter of the inhibition zone, the minimum inhibitory concentration (MIC), the growth curve, and the effect on the bacterial biofilm, respectively. Meanwhile, the antibacterial mechanism was also discussed from the aspects of cell wall integrity variation, cell membrane permeability, and the activities of related enzymes in the respiratory metabolic pathway before and after the intervention by MA. The results showed that MA had an inhibitory effect on eight kinds of pathogenic bacteria, and the MIC values for Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and Bacillus megaterium were 31.25, 62.5, 250, 125, 62.5, and 62.5 µg/mL, respectively. For instance, 31.25 µg/mL MA could inhibit the growth of Staphylococcus aureus within 28 h. The antibacterial mechanism experiments confirmed that MA could destroy the integrity of the cell membrane and cell wall of Staphylococcus aureus, causing the leakage of macromolecular substances, inhibiting the synthesis of soluble proteins, reducing the activities of succinate dehydrogenase and malate dehydrogenase, and interacting with DNA, leading to the relaxation and ring opening of supercoiled DNA. Besides, the activities of DNA topoisomerase I and II were both inhibited by MA, which led to the cell growth of Staphylococcus aureus being repressed. This study provides a theoretical basis and reference for the application of MA in the control and inhibition of food-borne Staphylococcus aureus.

Hydrogen sulfide alleviates chilling injury by modulating respiration and energy metabolisms in cold-stored peach fruit

The respiration and energy metabolisms of refrigerated peach fruit and their relationship to chilling injury (CI) treated with hydrogen sulfide (H2S) were investigated. Results showed that H2S treatment reduced the activities of hexokinase (HK), phosphor-glucose isomerase (PGI), phosphofructokinase (PFK) and pyruvate kinase (PK), and the contents of glucose, pyruvate and nicotinamide adenine dinucleotide (hydrogen) (NAD(H)) in the Embden-Meyerhof-Parnas (EMP) and tricarboxylic acid (TCA)-cycle compared to control and hypotaurine (HT, H2S scavenger) treatment, resulting in a lower respiration rate. Meanwhile, H2S treatment increased the activities of NADK, glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) and NADP(H) contents in the pentose phosphate pathway (PPP), while HT showed the opposite results. Moreover, H2S treatment induced the higher activities of adenosine triphosphatases (ATPases), succinic dehydrogenase (SDH) and cytochrome C oxidase (CCO) along with enhanced levels of ATP and energy charge, whereas HT suppressed energy generation, which increased cell membrane permeability and malondialdehyde content. Therefore, results suggested that H2S could maintain the integrity of the membrane structure by inhibiting the respiration and substance consumption in EMP pathway, increasing the proportion of PPP and energy supply to alleviate CI in peaches.

Efficiency and Mechanism of O3-SBBR Combined Process for Advanced Treatment of Biochemical Effluent from Printing and Dyeing Industrial Park

With the aim of addressing the difficult problem of biodegradable organic nitrogen in biochemical effluent of a printing and dyeing industrial park, the combined ozonation-sequencing batch biofilm reactor (O3-SBBR) process was used for advanced treatment. The influencing factors and degradation kinetics were analyzed; quenching experiments were carried out; and the types of free radicals, succinate dehydrogenase activity, and denitrification function genes were determined. The results showed that the suitable ozonation condition was pH 8.0-8.5, O3 concentration was approximately 35.0 mg·L-1, O3 dosage was approximately 100.0 mg·L-1, and reaction time was 90.0-120.0 min. Organic nitrogen in the biochemical effluent by ozonation conformed to the pseudo first-order kinetic model, and the maximum rate constant k was 0.01035 min-1 (experimental conditions:pH 8.0, ozone dosage 150.0 mg·L-1, and ozone concentration 35.0 mg·L-1). Ozonation significantly improved the denitrification performance of the sequencing biofilm batch reactor (SBBR), and the denitrification efficiency increased from 19.8% (SBBR) to 32.9% (O3-SBBR). Ozonation could convert organic nitrogen and organic substances with strong toxicity and difficult biological utilization into small molecular substances with low toxicity and biodegradability. The abundance of functional genes (nirS, nirK, and nor) in the O3-SBBR combined process was significantly higher than that in the single SBBR, which further confirmed that ozonation could improve the nitrogen removal performance of SBBR. The operation cost of the combined process was 0.74-1.07 yuan·m-3, with good technical economy. This study provided a basis for the application of the O3-SBBR combined process in the advanced treatment of biochemical effluent in printing and dyeing industrial parks.

Studies of the silkworm enzyme activity and their correlations with economic variables

The experiment was conducted to analyse the larval performance and economic traits of bivoltine silkworm breeds of silkworm (SK-1, SK-6, SK-22, SK-28, SK-33, CSR4, CSR2, NB4D2, DUN6 and APS4) during spring season. The haemolymph total protein, succinate and gultamate dehydrogenase activities were estimated and their correlation with economic traits were also worked out. The results of the study confirmed that among ten bivoltine silkworm breeds, highest haemolymph SDH activity of 3.47 µmoles/ml/mgprotein/min was recorded in the silkworm breed SK1 and least SDH activity of 1.58 µmoles/ml/mg protein/min was recorded in the breed APS4. The highest peak of succinate dehydrogenase activity of 2.65 µmoles/ml/mg protein/min was observed on 7th day of the 5th instar and lowest peak of succinate dehydrogenase activity of 2.39 µmoles/ml/mg protein/min was observed on 4th day of the 5th instar. GDH activity of 0.46 µmoles/ml/mg protein/min was recorded highest in the silkworm breed SK1 and lowest of 0.15 µmoles/ml/mg protein/min was recorded in silkworm breed APS4. The highest peak of haemolymph GDH of 0.36 µmoles/ml/mg protein/min was recorded on 7th day of 5th instar and lowest peak of 0.26 µmoles/ml/mg protein/min was recorded on 4th day of 5th instar. The correlational studies revealed that haemolymph total protein, SDH and GDH were found to be positively corelated with yield by weight and number (cocoon), weight of mature larvae, shell weight ,cocoon weight, shell ratio percent, silk productivity, rate of pupation, fecundity, raw silk percentage and length of filament. Thus, the study revealed that silkworm breeds like SK1, SK6, SK22 and SK28 as productive breeds and hence may be used for future breeding programmes for evolution of new robust silkworm breeds

Postharvest trehalose application alleviates chilling injuring of cold storage guava through upregulation of SnRK1 and energy charge

Sucrose non-fermenting-1-related protein kinases-1 (SnRK1) plays a crucial role in response to energy homeostasis for plant survival during exposure to environmental stresses. Trehalose has been reported as chilling injury alleviating agent of postharvest guava (Psidium guajava cv. Kim Ju), but the mechanism related to energy homeostasis have not been elucidated. This research is focusing on the influence of exogenous trehalose on SnRK1 activation associated with energy homeostasis and chilling injury incidence of ‘Kim Ju’ guava fruit during low temperature storage. The fruits were treated with 0 and 200 mM of trehalose for 30 min and kept at 8 °C for 14 d. It was demonstrated that PgSnRK1 expression and SnRK1 activity increased after trehalose treatment, reaching maximum within 1–2 d. Trehalose treatment upregulated the expression of energy producing related genes including adenosine triphosphate synthase subunit β and adenosine diphosphate/adenosine triphosphate carrier and increased the enzyme activities of nicotinamide adenine dinucleotide dehydrogenase, succinate dehydrogenase and cytochrome c oxidase. These events were accompanied by higher energy charge and lower chilling injury throughout storage. The increase in SnRK1 activity by exogenous trehalose was closely associated with an increase in sucrose level during the first 2 d of storage. The SnRK1 activation was induced apparently by 50–200 mM exogenous sucrose within 3–12 h after treatment while exogenous trehalose treatment induced SnRK1 activation slightly and slowly within 2 d. Moreover, validamycin A combined with exogenous trehalose enhanced the cellular trehalose accumulation while sucrose level remained constant which lowered PgSnRK1 expression. Our results suggested that exogenous trehalose induces a transient rise in sucrose content at the early storage for providing the sugar signaling to SnRK1 activation which is required for maintaining energy homeostasis accompanied by retarding chilling injury.

Diglycolic acid inhibits succinate dehydrogenase activity, depletes mitochondrial membrane potential, and induces inflammation in an SH-SY5Y neuroblastoma model of neurotoxicity in vitro

Diethylene glycol is a toxic industrial solvent resulting in a well-defined toxidrome. Diglycolic acid (DGA) has been identified as the metabolite responsible for the nephrotoxicity and hepatotoxicity. These studies assess the mechanism of DGA-induced neurotoxicity, specifically addressing the known ability of DGA to chelate calcium (Ca2+) in solution and inhibit mitochondrial complex II. SH-SY5Y cells were seeded into 96-well plates to assess intracellular Ca2+ chelation, complex II activity, mitochondrial membrane potential (ΔΨm), ATP production, and release of inflammatory cytokines TNF-α and IL-1β with 2-, 4-, 6-, 24-, and 48-h DGA exposure. Peak Ca2+ chelation occurred at 4 h in cells treated with 6.25–50 mM DGA; however, effects were transient. Complex II activity was significantly decreased at all DGA concentrations tested, with 12.5 mM DGA causing 80% inhibition and 25 and 50 mM DGA causing 97 and 100% inhibition, respectively. Subsequently, 12.5–50 mM DGA concentrations significantly decreased ΔΨm at all time points. 50 mM DGA significantly increased release of TNF-α and IL-1β after 24 and 48 h with significantly decreased ATP production observed at the same time points and concentration. These studies demonstrate that the DGA-induced mechanism of SH-SY5Y cell death involves complex II inhibition leading to mitochondrial depolarization, and subsequent ATP depletion with accompanying inflammatory cytokine release. These results indicate a direct mechanism of DGA-induced neurotoxicity in vitro, similarly observed in other DEG-affected target organs.

An Overview of the Pathophysiological Mechanisms of 3-Nitropropionic Acid (3-NPA) as a Neurotoxin in a Huntington's Disease Model and Its Relevance to Drug Discovery and Development.

Animal models are used to better understand the various mechanisms involved in the pathogenesis of diseases and explore potential pathways that will aid in discovering therapeutic targets. 3-Nitropropionic Acid (3-NPA) is a neurotoxin used to induce Huntington's disease (HD)-like symptoms in experimental animals. The 3-NPA is a fungus toxin that impairs the complex II (succinate dehydrogenase) activity of the mitochondria and reduces ATP synthesis, leading to excessive production of free radicals resulting in the degeneration of GABAergic medium spiny neurons (MSNs) in the striatum. This is characterized by motor impairments a key clinical manifestation of HD. 3-NPA has the potential to alter several cellular processes, including mitochondrial functions, oxidative stress, apoptosis, and neuroinflammation mimicking HD-like pathogenic conditions in animals. This review strives to provide a new insight towards the 3-NPA induced molecular dysfunctioning in developing an animal model of HD. Moreover, we summarise several preclinical studies that support the use of the 3-NPA-induced models for drug discovery and development in HD. This review is a collection of various articles that were published from 1977 to 2022 on Pubmed (1639), Web of Science (2139), and Scopus (2681), which are related to the 3-NPA induced animal model.

Changes in gene expression and enzyme activity related to glucose metabolism in the livers of Brandt's voles (Lasiopodomys brandtii) exposed to hypoxia

Brandt's vole (Lasiopodomys brandtii) is a hypoxia-tolerant species, and the metabolic characteristics of hypoxia-tolerant species have become a focus of recent research. However, insights into the anaerobic and aerobic metabolism of the livers of Brandt's voles under hypoxia remain limited. In this study, Brandt's voles and hypoxia-intolerant Kunming mice (Mus musculus, control species) were exposed to hypoxia conditions (Brandt's voles, 10% and 7.5% O2; Kunming mice, 10% O2) for 24 h, and changes in gene expression and enzyme activity related to anaerobic and aerobic metabolism in the livers were evaluated. Phosphofructokinase 1 (PFK1), phosphofructokinase 2 (PFK2), pyruvate kinase muscle (PKM), hexokinase 2 (HK2), and lactate dehydrogenase (LDH) related to anaerobic metabolism in the livers of Brandt's voles were increased under 7.5% O2. Regarding gene expression and enzyme activity for aerobic metabolism in Brandt's voles under 7.5% and 10% O2, pyruvate dehydrogenase kinase 1 (PDK1) expression was up-regulated, and succinate dehydrogenase (SDH) activity was decreased. In the livers of Kunming mice, gene expression related to anaerobic and aerobic metabolism was increased at the late stage of 10% O2, and SDH activity was enhanced at 6 h and reduced at 18 h. In addition, PFK1,PKM, PDK1 expression and SDH activity in Brandt's voles were significantly correlated with HIF-1a expression. PFK1, PKM, LDHand PDK1 expression in Kunming mice were significantly correlated with HIF-1a expression. These findings indicate that the livers of Brandt's voles have a certain tolerance to hypoxia, and metabolic changes play important roles in hypoxia tolerance.

Tilianin extracted from Xiangqinglan () inhibits apoptosis induced by mitochondrial pathway and endoplasmic reticulum stress in H9c2 cells after oxygen-glucose deprivation/reoxygenation.

To investigate the efficacy of tilianin extracted from Xiangqinglan () on apoptosis of H9c2 cell after oxygen-glucose deprivation/reoxygenation (OGD/R) and the mechanism. Tilianin was obtained from Beijing Inluck Science and Technology Development Co. Ltd., with purity ≥ 98%. The OGD/R model was established in H9c2 cells. Flow cytometry detected the mitochondrial membrane potential, apoptosis rates, mitochondrial reactive oxygen species (ROS) and calcium ion concentration. Succinate dehydrogenase (SDH) activity, succinate content and levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1 β (IL-1β) were detected with enzyme-linked immunosorbent assay. Western blot measured protein levels. Tilianin significantly reduced the apoptotic rates, ROS levels, calcium ion concentration, succinate content, and, levels of TNF-α, IL-6 and IL-1β of OGD/R cells, while significantly increased the membrane potential and SDH activity in mitochondria. Western blot analysis showed that tilianin significantly up-regulated p-Calmodulin-dependent protein kinase Ⅱ and voltage-dependent anion selective channel levels in OGD/R cells, while significantly down-regulated p-protein kinase B, Bcl-2-associated X, and dynamin-related protein 1 levels related to apoptosis in the mitochondrial pathway. Moreover, tilianin significantly up-regulated B-cell lymphoma-2 and mitochondrial protein 2 related to the inhibition of apoptosis. Furthermore, tilianin down-regulated phosphorylated-apoptosis signal-regulated kinase 1, phosphorylated-p38 and C/EBP homologous protein related to endoplasmic reticulum stress. Tilianin may inhibit OGD/R-induced H9c2 cell apoptosis mediated by mitochondrial pathway and endoplasmic reticulum stress, thus protecting cardiomyocytes.

Preparation and antimicrobial mechanism of Maillard reaction products derived from ε-polylysine and chitooligosaccharides

Chitooligosaccharides can be combined with amino acids or polypeptide to form Maillard reaction products (MRPs) with the antibacterial characteristics through Maillard reaction. This research aims to clarify the structure, antimicrobial effect and mechanism against Shewanella putrefaciens (S. putrefaciens) of ε-polylysine and chitooligosaccharides Maillard reaction products (LC-MRPs). The results of intrinsic fluorescence (IF) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction, proton nuclear magnetic resonance (1H NMR) spectra and scanning electron microscope (SEM) indicated Maillard reaction occurred between ε-polylysine and chitooligosaccharides. The observation of confocal laser scanning microscopy (CLSM), SEM and growth curves of S. putrefaciens evidenced that LC-MRPs have the strongest antibacterial effects. The leakage of alkaline phosphatase (AKP) and lactate dehydrogenase (LDH) implied that LC-MRPs sabotaged bacterial barrier (cell wall and cell membrane). The changes in content of nucleic acids, reactive oxygen species (ROS) level, lipid peroxidation content (LPO), succinate dehydrogenase (SDH) activity and adenosine triphosphate (ATP) content showed LC-MRPs will affect bacterial genetic gene transcription, material and energy metabolism. Therefore, the LC-MRPs were effective antibacterial agents to inhibit S. putrefaciens, which will help to preserve food with S. putrefaciens as the main spoilage bacteria.

Mitochondrial SENP2 regulates the assembly of SDH complex under metabolic stress.

Succinate dehydrogenase (SDH) is a heterotetrameric enzyme complex belonging to the mitochondrial respiratory chain and uniquely links the tricarboxylic acid (TCA) cycle with oxidative phosphorylation. Cancer-related SDH mutations promote succinate accumulation, which is regarded as an oncometabolite. Post-translational modifications of SDH complex components are known to regulate SDH activity, although the contribution of SUMOylation remains unclear. Here, we show that SDHA is SUMOylated by PIAS3 and deSUMOylated by SENP2, events dictating the assembly and activity of the SDH complex. Moreover, CBP acetylation of SENP2 negatively regulates its deSUMOylation activity. Under glutamine deprivation, CBP levels decrease, and the ensuing SENP2 activation and SDHA deSUMOylation serve to concurrently dampen the TCA cycle and electron transport chain (ETC) activity. Along with succinate accumulation, this mechanism avoids excessive reactive oxygen species (ROS) production to promote cancer cell survival. This study elucidates a major function of mitochondrial-localized SENP2 and expands our understanding of the role of SUMOylation in resolving metabolic stress.