Nonmetabolic functions of metabolic enzymes in cancer development

Metabolism is a fundamental biological process composed of a series of reactions catalyzed by metabolic enzymes. Emerging evidence demonstrates that the aberrant signaling in cancer cells induces nonmetabolic functions of metabolic enzymes in many instrumental cellular activities, which involve metabolic enzyme-mediated protein post-translational modifications, such as phosphorylation, acetylation, and succinylation. In the most well-researched literatures, metabolic enzymes phosphorylate proteins rather than their metabolites as substrates. Some metabolic enzymes have altered subcellular localization, which allows their metabolic products to directly participate in nonmetabolic activities. This review discusses how these findings have deepened our understanding on enzymes originally classified as metabolic enzymes, by highlighting the nonmetabolic functions of several metabolic enzymes responsible for the development of cancer, and evaluates the potential for targeting these functions in cancer treatment.

Different mitochondrial genetic defects exhibit the same protein signature of metabolism in skeletal muscle of PEO and MELAS patients: A role for oxidative stress

A major challenge in mitochondrial diseases (MDs) is the identification of biomarkers that could inform of the mechanisms involved in the phenotypic expression of genetic defects. Herein, we have investigated the protein signature of metabolism and of the antioxidant response in muscle biopsies of clinically and genetically diagnosed patients with Progressive External Ophthalmoplegia due to single large-scale (PEO-sD) or multiple (PEO-mD) deletions of mtDNA and Mitochondrial Encephalopathy Lactic Acidosis and Stroke-like episode (MELAS) syndrome, and healthy donors. A high-throughput immunoassay technique that quantitates the expression of relevant proteins of glycolysis, glycogenolysis, pentose phosphate pathway, oxidative phosphorylation, pyruvate and fatty acid oxidation, tricarboxylic acid cycle and the antioxidant response in two large independent and retrospectively collected cohorts of PEO-sD, PEO-mD and MELAS patients revealed that despite the heterogeneity of the genetic alterations, the three MDs showed the same metabolic signatures in both cohorts of patients, which were highly divergent from those of healthy individuals. Linear Discriminant Analysis and Support Vector Machine classifier provided a minimum of four biomarkers to discriminate healthy from pathological samples. Regardless of the induction of a large number of enzymes involved in ameliorating oxidative stress, the down-regulation of mitochondrial superoxide dismutase (SOD2) and catalase expression favored the accumulation of oxidative damage in patients' proteins. Down-regulation of SOD2 and catalase expression in MD patients is not due to relevant changes in the availability of their mRNAs, suggesting that oxidative stress regulates the expression of the two enzymes post-transcriptionally. We suggest that SOD2 and catalase could provide specific targets to improve the detoxification of reactive oxygen species that affects muscle proteins in these patients.

Research on the mechanism of drug-drug interaction between salvianolate injection and aspirin based on the metabolic enzyme and PK-PD model: study protocol for a PK-PD trial

Background

Coronary heart disease (CHD) is a common cardiovascular disease accounting for 10–20% mortality by heart disease worldwide. The gold standard treatment to manage CHD is aspirin, which may prevent myocardial infarction and sudden death; however, long-term use of aspirin may increase its side effects. Currently, more and more clinicians are exploring different approaches to use the right combination of medicine to enhance the efficacy and reduce side effects. Salvianolate can significantly inhibit the aggregation and activation of platelets in patients with CHD; however, its optimum combination with western medicine is not established or supported by clinical trial results.

Methods/design

This trial is a prospectively planned, open-labeled, parallel-grouped, single-centered clinical trial with aggregated pharmacodynamics-pharmacokinetics (PK-PD) data. All treatment courses will last for 10 days and blood sample will be acquired before administration on days 8, 9, and 10, and after administration at 5 min, 15 min, 30 min, 45 min, 1 h, 2 h, 4 h, 8 h, 12 h, and 24 h on day 10. This trial uses PK-PD modeling to provide a description of the concentration–effect relationship and an estimate of pharmacological potency of the medicine. The primary outcome will be changes in aspirin esterase and catechol-o-methyltransferase (COMT) activity at different blood concentrations to determine the PK-PD characteristics of the combination of salvianolate and aspirin, followed by analysis of the correlation between exposure level and pharmacodynamic index of the medicines.

Discussion

This trial will aim to evaluate the relationship between changes in the pharmacokinetics and therapeutic effect index in the combined use of salvianolate and aspirin. It also discusses the possible mechanism of medicine combination in the treatment for CHD and provides an experimental basis for a clinically rational medicine combination.

Trial registration

ClinicalTrials.gov, NCT03306550. Registered on 9 October 2017. ClinicalTrials.gov https://register.clinicaltrials.gov/prs/app/action/SelectProtocol?sid=S0007D8H&selectaction=Edit&uid=U0003QY8&ts=2&cx=oiuc9g

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2861-7) contains supplementary material, which is available to authorized users.

Metabolic intermediates - Cellular messengers talking to chromatin modifiers

BACKGROUND

To maintain homeostasis, cells need to coordinate the expression of their genes. Epigenetic mechanisms controlling transcription activation and repression include DNA methylation and post-translational modifications of histones, which can affect the architecture of chromatin and/or create 'docking platforms' for multiple binding proteins. These modifications can be dynamically set and removed by various enzymes that depend on the availability of key metabolites derived from different intracellular pathways. Therefore, small metabolites generated in anabolic and catabolic processes can integrate multiple external and internal stimuli and transfer information on the energetic state of a cell to the transcriptional machinery by regulating the activity of chromatin-modifying enzymes.

SCOPE OF REVIEW

This review provides an overview of the current literature and concepts on the connections and crosstalk between key cellular metabolites, enzymes responsible for their synthesis, recycling, and conversion and chromatin marks controlling gene expression.

MAJOR CONCLUSIONS

Whereas current evidence indicates that many chromatin-modifying enzymes respond to alterations in the levels of their cofactors, cosubstrates, and inhibitors, the detailed molecular mechanisms and functional consequences of such processes are largely unresolved. A deeper investigation of mechanisms responsible for altering the total cellular concentration of particular metabolites, as well as their nuclear abundance and accessibility for chromatin-modifying enzymes, will be necessary to better understand the crosstalk between metabolism, chromatin marks, and gene expression.

Hidden features: exploring the non-canonical functions of metabolic enzymes

The study of cellular metabolism has been rigorously revisited over the past decade, especially in the field of cancer research, revealing new insights that expand our understanding of malignancy. Among these insights is the discovery that various metabolic enzymes have surprising activities outside of their established metabolic roles, including in the regulation of gene expression, DNA damage repair, cell cycle progression and apoptosis. Many of these newly identified functions are activated in response to growth factor signaling, nutrient and oxygen availability, and external stress. As such, multifaceted enzymes directly link metabolism to gene transcription and diverse physiological and pathological processes to maintain cell homeostasis. In this Review, we summarize the current understanding of non-canonical functions of multifaceted metabolic enzymes in disease settings, especially cancer, and discuss specific circumstances in which they are employed. We also highlight the important role of subcellular localization in activating these novel functions. Understanding their non-canonical properties should enhance the development of new therapeutic strategies for cancer treatment.

Summary: This Review summarizes recent findings about multifaceted metabolic enzymes with non-canonical activities outside their core biochemical functions, and how they may provide new therapeutic strategies for cancers.

Substitution of soybean meal with fermented Jatropha kernel meal: effect on growth performance, body composition, and metabolic enzyme activity of Labeo rohita

A 60-day feeding trial was conducted to evaluate the nutritional potential of fermented Jatropha kernel meal (FJKM) in the diets of rohu, Labeo rohita, fingerlings. Four iso-nitrogenous (336 g kg-1) and iso-energetic (20 MJ kg-1) diets containing 0, 100, 200, and 300 g kg-1 FJKM in replacement of 0, 33.3, 66.7, and 100% soybean meal protein, respectively, were prepared and designated as control, T1, T2, and T3, respectively. A total of 180 acclimatized fish (average weight 6.05 ± 0.04 g) were equally distributed into four experimental groups in triplicates, and were fed their respective diets to satiation twice daily at 10:00 h and 18:00 h. Higher percent weight gain (%WG); specific growth rate (SGR); protein efficiency ratio (PER); protease, aspartate amino transferase (AST), and alanine amino transferase (ALT) activities; and lower feed conversion ratio (FCR) were recorded in T2 and T3 groups compared to other groups. Whereas hepatosomatic index (HSI), intestinal somatic index (ISI), and amylase, lactate dehydrogenase (LDH), malate dehydrogenase (MDH), superoxide dismutase (SOD), and catalase activities among the various dietary groups did not vary significantly (P > 0.05). Whole body composition of fish analyzed at the end of the feeding trial exhibited significantly (P < 0.05) higher ether extract and lower crude protein in the control group compared to the FJKM-fed groups. These results indicated that rohu fingerlings can efficiently utilize FJKM without any detrimental effect on growth performance, nutrient utilization, and metabolic response.

Genetic alterations affecting the genes encoding the enzymes of the kynurenine pathway and their association with human diseases

Tryptophan is metabolized primarily via the kynurenine pathway (KP), which involves several enzymes, including indoleamine 2,3-dioxygenase, tryptophan 2,3 dioxygenase (TDO), kynurenine aminotransferases (KATs), kynurenine monooxygenase (KMO) etc. The majority of metabolites are neuroactive: some of them, such as kynurenic acid, show neuroprotective effects, while others contribute to free radical production, leading to neurodegeneration. Imbalance of the pathway is assumed to contribute to the development of several neurodegenerative diseases, psychiatric disorders, migraine and multiple sclerosis. Our aim was to summarize published data on genetic alterations of enzymes involved in the KP leading to disturbances of the pathway that can be related to different diseases. To achieve this, a PubMed literature search was performed for publications on genetic alterations of the KP enzymes upto April 2017. Several genetic alterations of the KP have been identified and have been proposed to be associated with diseases. Here we must emphasize that despite the large number of recognized genetic alterations, the number of firmly established causal relations with specific diseases is still small. The realization of this by those interested in the field is very important and finding such connections should be a major focus of related research. Polymorphisms of the genes encoding the enzymes of the KP have been associated with autism, multiple sclerosis and schizophrenia, and were shown to affect the immune response of patients with bacterial meningitis, just to mention a few. To our knowledge, this is the first comprehensive review of the genetic alterations of the KP enzymes. We believe that the identification of genetic alterations underlying diseases has great value regarding both treatment and diagnostics in precision medicine, as this work can promote the understanding of pathological mechanisms, and might facilitate medicinal chemistry approaches to substitute missing components or correct the disturbed metabolite balance of KP.

Metabolic enzymes dysregulation in heart failure: the prospective therapy

The heart failure accounts for the highest mortality rate all over the world. The development of preventive therapeutic approaches is still in their infancy. Owing to the extremely high energy demand of the heart, the bioenergetics pathways need to respond efficiently based on substrate availability. The metabolic regulation of such heart bioenergetics is mediated by various rate limiting enzymes involved in energy metabolism. Although all the pertinent mechanisms are not clearly understood, the progressive decline in the activity of metabolic enzymes leading to diminished ATP production is known to cause progression of the heart failure. Therefore, metabolic therapy that can maintain the appropriate activities of metabolic enzymes can be a promising approach for the prevention and treatment of the heart failure. The flavonoids that constitute various human dietary ingredients also effectively offer a variety of health benefits. The flavonoids target a variety of metabolic enzymes and facilitate effective management of the equilibrium between production and utilization of energy in the heart. This review discusses the broad impact of metabolic enzymes in the heart functions and explains how the dysregulated enzyme activity causes the heart failure. In addition, the prospects of targeting dysregulated metabolic enzymes by developing flavonoid-based metabolic approaches are discussed.

Glycemic response after glucose oral administration of wild juvenile red grouper Epinephelus morio fed two different diets

Epinephelus morio is a large carnivorous species of the Caribbean Sea under reproduction in captivity and nutritional physiology. A diet with raw cornstarch (RCS) was compared to a basal diet without starch (basal) to measure plasma glucose, liver glycogen, and intermediary metabolism. Glucose level did not change (p > 0.05) whereas liver glycogen was significantly higher in fish fed the RCS diet (137.2 ± 14.5 mg g^-1) than in fish fed the basal diet (87.4 ± 14.5 mg g^-1). Oral glucose administration (170 mg glucose per 100 g body weight) yielded a slight change; two peaks of plasma glucose were recorded with basal (5.6 mM L^-1) 2 h after oral administration and at 12 h (6.4 mM L^-1). After 24 h, with 1.7 mM L^-1, fish returned to initial stage (2.4 mM L^-1). RCS diet produced the highest level (6.3 mM L^-1) 2 h after oral administration; lowest level observed at 24 h after oral administration (1.0 mM L^-1). A significant effect was detected with the presence or absence of dietary carbohydrates (CBH) on hepatic fructose 1,6-bisphosphatase and pyruvate kinase activity. Grouper used two strategies to maintain glucose homeostasis: CBH present in the diet oriented towards gluconeogenesis, whereas no dietary CBH enhanced glycolytic route to liberate glucose and increase liver glycogen.

Some immunological responses of common carp (Cyprinus carpio) fingerling to acute extremely low-frequency electromagnetic fields (50 Hz)

Increasing of anthropogenic electromagnetic fields in aquatic environments has been recently become the core of attention. In this study, the effect of extremely low-frequency electromagnetic fields (50 Hz) on immune status and metabolic markers of common carp fingerling was assessed. The fish were exposed to extremely low-frequency electromagnetic fields at four intensities of 0.1, 0.5, 1, and 2 mT only once for 2 h; then, they were reared for 60 days. Results showed that the levels of aspartate aminotransferase (AST) and alanine transaminase (ALT) and alkaline phosphatase (ALP) were increased with an increase in the electromagnetic field intensity on 15 and 60 days post exposure. A significant increase was obtained in these enzyme levels in all the tested intensities compared to the control one (p < 0.05), with a maximum value measured in 2-mT trail. Conversely, with an increasing in the electromagnetic intensity, the levels of C3, C4, and lysozyme were reduced in all the treated groups in comparison with the control group (p < 0.05). The results suggested a significant impact of electromagnetic on fish immunophysiological functions. Therefore, it is required to have serious attention in aquatic ecosystems.

Soybean saponin modulates nutrient sensing pathways and metabolism in zebrafish

Soybean saponin (SA) is known as a major anti-nutritional factor that causes metabolic disturbances and growth reduction in fish. However, the mechanisms underlying these effects were far from fully understood. In particular, the influences of SA on nutrient sensing and downstream metabolic pathways remain largely unexplored. Using zebrafish as an animal model, this study was conducted to examine the phenotypic and molecular responses after dietary SA treatment for 2 weeks. SA at both 5 and 10 g/kg diet levels significantly reduced growth performance and feed efficiency, and damaged the morphology of the intestinal mucosa. SA stimulated AMP-activated protein kinase but reduced target of rapamycin (TOR) activities in both feeding trial and cellular studies. Furthermore, SA increased the mRNA expressions of growth axis genes including growth hormone, insulin-like growth factor 1, growth hormone receptor A, and growth hormone receptor B, but decreased insulin-like growth factor-binding protein 2 at both mRNA and protein levels. SA also increased the expressions of key metabolic enzymes involved in glutamine synthetase, glutamate dehydrogenase and lipolysis, hormone-sensitive lipase and lipoprotein lipase. Our results demonstrated that SA modulated nutrient sensing pathways and metabolism, thus provide new aspects on the explanation of the physiological effects of SA.

Nuclear localization of metabolic enzymes in immunity and metastasis

Metabolism is essential to all living organisms that provide cells with energy, regulators, building blocks, enzyme cofactors and signaling molecules, and is in tune with nutritional conditions and the function of cells to make the appropriate developmental decisions or maintain homeostasis. As a fundamental biological process, metabolism state affects the production of multiple metabolites and the activation of various enzymes that participate in regulating gene expression, cell apoptosis, cancer progression and immunoreactions. Previous studies generally focus on the function played by the metabolic enzymes in the cytoplasm and mitochondrion. In this review, we conclude the role of them in the nucleus and their implications for cancer progression, immunity and metastasis.

DNA damage and repair, oxidative stress and metabolism biomarker responses in lungs of rats exposed to ambient atmospheric 1-nitropyrene

1-Nitropyrene (1-NP) is a mutagenic and carcinogenic pollutant very widespread in the environment. However, the relative investigations on genotoxicity, oxidative stress and metabolic enzymes in lungs of mammalian caused by 1-NP have not been fully established. In this study, the 1-NP solutions at 3 dosages (1.0×10^-5, 4.0×10^-5 and 1.6×10^-4mg/kg body weight) were respectively given to rats by the intratracheal instillation. The responses of 1-NP on DNA damage and repair, oxidative stress and metabolism biomarkers in rat lungs after exposure to 1-NP were measured. The results showed 1-NP at three dosages induced obvious DNA strand breaks, 8-OH-dG formation and DNA-protein cross-link in rat lungs compared with the control. Higher dosage 1-NP (4.0×10^-5 and 1.6×10^-4mg/kg body weight) greatly activated DNA repair gene OGG1 and inhibited MTH1 and XRCC1 expressions, and they significantly elevated the levels of GADD153, heme oxygenase-1 and malondialdehyde and decreased SOD activity, accompanied by the increases of CYP450, CYP1A1, CYP1A2 and GST levels. These results suggested the genotoxicity of 1-NP might rely on 1-NP-caused DNA damage and its combined effects on the suppression of DNA repair and the enhancement of oxidative stress and metabolic enzyme activity.

Regulation of maize kernel weight and carbohydrate metabolism by abscisic acid applied at the early and middle post-pollination stages in vitro

Abscisic acid (ABA) accumulates in plants under drought stress, but views on the role of ABA in kernel formation and abortion are not unified. The response of the developing maize kernel to exogenous ABA was investigated by excising kernels from cob sections at four days after pollination and culturing in vitro with different concentrations of ABA (0, 5, 10, 100μM). When ABA was applied at the early post-pollination stage (EPPS), significant weight loss was observed at high ABA concentration (100μM), which could be attributed to jointly affected sink capacity and activity. Endosperm cells and starch granules were decreased significantly with high concentration, and ABA inhibited the activities of soluble acid invertase and acid cell wall invertase, together with earlier attainment of peak values. When ABA was applied at the middle post-pollination stage (MPPS), kernel weight was observably reduced with high concentration and mildly increased with low concentration, which was regulated due to sink activity. The inhibitory effect of high concentration and the mild stimulatory effect of low concentration on sucrose synthase and starch synthase activities were noted, but a peak level of ADP-glucose pyrophosphorylase (AGPase) was stimulated in all ABA treatments. Interestingly, AGPase peak values were advanced by low concentration and postponed by high concentration. In addition, compared with the control, the weight of low ABA concentration treatments were not statistically significant at the two stages, whereas weight loss from high concentration applied at EPPS was considerably obvious compared with that of the MPPS, but neither led to kernel abortion. The temporal- and dose-dependent impacts of ABA reveal a complex process of maize kernel growth and development.

Metabolic side effects induced by olanzapine treatment are neutralized by CB1 receptor antagonist compounds co-administration in female rats

Weight gain is an important side effect of most atypical antipsychotic drugs such as olanzapine. Moreover, although many animal models with metabolic side effects have been well defined, the interaction with other pathways has to be considered. The endocannabinoid system and the CB1 receptor (CB1R) are among the most promising central and peripheral targets involved in weight and energy balance. In this study we developed a rat model based 15-days treatment with olanzapine that shows weight gain and an alteration of the blood parameters involved in the regulation of energy balance and glucose metabolism. Consequently, we analysed whether, and by which mechanism, a co-treatment with the novel CB1R neutral antagonist NESS06SM, could attenuate the adverse metabolic effects of olanzapine compared to the reference CB1R inverse agonist rimonabant. Our results showed alterations of the cannabinoid markers in the nucleus accumbens and of orexigenic/anorexigenic markers in the hypothalamus of female rats treated with olanzapine. These molecular modifications could explain the excessive food intake and the resulting weight gain. Moreover, we confirmed that a co-treatment with CB1R antagonist/inverse agonist compounds decreased food intake and weight increment and restored all blood parameters, without altering the positive effects of olanzapine on behaviour. Furthermore, rimonabant and NESS06SM restored the metabolic enzymes in the liver and fat tissue altered by olanzapine. Therefore, CB1 receptor antagonist/inverse agonist compounds could be good candidate agents for the treatment of weight gain induced by olanzapine.

Striking Diversity in Holoenzyme Architecture and Extensive Conformational Variability in Biotin-Dependent Carboxylases

Biotin-dependent carboxylases are widely distributed in nature and have central roles in the metabolism of fatty acids, amino acids, carbohydrates, and other compounds. The last decade has seen the accumulation of structural information on most of these large holoenzymes, including the 500-kDa dimeric yeast acetyl-CoA carboxylase, the 750-kDa α₆β₆ dodecameric bacterial propionyl-CoA carboxylase, 3-methylcrotonyl-CoA carboxylase, and geranyl-CoA carboxylase, the 720-kDa hexameric bacterial long-chain acyl-CoA carboxylase, the 500-kDa tetrameric bacterial single-chain pyruvate carboxylase, the 370-kDa α₂β₄ bacterial two-subunit pyruvate carboxylase, and the 130-kDa monomeric eukaryotic urea carboxylase. A common theme that has emerged from these studies is the dramatic structural flexibility of these holoenzymes despite their strong overall sequence conservation, evidenced both by the extensive diversity in the architectures of the holoenzymes and by the extensive conformational variability of their domains and subunits. This structural flexibility is crucial for the function and regulation of these enzymes and identifying compounds that can interfere with it represents an attractive approach for developing novel modulators and drugs. The extensive diversity observed in the structures so far and its biochemical and functional implications will be the focus of this review.

Acute toxicity, biochemical and histopathological responses of endosulfan in Chanos chanos

This study investigated 96h median lethal concentration of endosulfan (99%, pure α: β ratio of 7:3) by conducting static non-renewable acute toxicity bio-assay in Chanos chanos juvenile with average weight (110±5.65g). Further, the effect of different definitive doses (18.5, 19.5, 20.5, 21.5 and 22.5µg/L) of endosulfan on metabolic, heamato-immunoligcal and histopathological response were probed. Anti-oxidative enzymes CAT, SOD and GST showed significant (p<0.01) increase of activity in the liver, gill and brain during exposure to endosulfan in a dose and time dependent manner. The brain AChE activity showed significant (p<0.01) inhibition from 18.5 to 22.5µg/L exposure of endosulfan than the control group. LDH and MDH activity gradually increased with consequent increasing dose of endosulfan exposure in the liver, gill and brain. Similarly, ALT, AST and G6PDH activities in both liver and gill increased with consequent increases in the dose of endosulfan exposure. Immunological profile such as blood glucose and serum cortisol level significantly enhanced while respiratory burst activity declined with consequent increasing doses of endosulfan exposure. Histopathological alteration in the gill demonstrated curling of secondary lamellae, thickening of primary epithelium, shorting of secondary lamellae, epithelial hyperplasia, fusion of secondary lamellae, aneurism, and collapsed secondary lamellae due to dose dependent exposure of endosulfan. Liver histology illustrated cloudy swelling and necrosis with pyknotic nuclei to the moderate dose of endosulfan, whereas higher dose of endosulfan (21.5µg/L) displayed severe necrosis of hepatic cells. Overall results clearly indicate that acute exposure of endosulfan led to pronounced deleterious alterations on biochemical, heamato-immunological, and histopathological responses of C. chanos juvenile.

Metabolic cost of osmoregulation in a hypertonic environment in the invasive African clawed frog Xenopus laevis

Studies of aquatic invertebrates reveal that salinity affects feeding and growth rates, reproduction, survival, and diversity. Little is known, however, about how salinity impacts the energy budget of vertebrates and amphibians in particular. The few studies focused on this topic in vertebrates suggest that the ingestion of salts and the resulting osmoregulatory activity is energetically expensive. We analyzed the effect of saline acclimation on standard metabolic rates (SMR) and the activities of metabolic enzymes of internal organs and osmoregulatory variables (plasma osmolality and urea plasma level) in females of Xenopus laevis by means of acclimating individuals to an isosmotic (235 mOsm NaCl; ISO group) and hyper-osmotic (340 mOsm NaCl; HYP group) environment for 40 days. After acclimation, we found that total and mass-specific SMR was approximately 80% higher in the HYP group than those found in the ISO group. These changes were accompanied by higher citrate synthase activities in liver and heart in the HYP group than in the ISO group. Furthermore, we found a significant and positive correlation between metabolic rates and plasma urea, and citrate synthase activity in liver and heart. These results support the notion that the cost of osmoregulation is probably common in most animal species and suggest the existence of a functional association between metabolic rates and the adjustments in osmoregulatory physiology, such as blood distribution and urea synthesis.

The effect of copper nanoparticles supplementation on freshwater prawn Macrobrachium rosenbergii post larvae

The present study was performed to assess the effects of dietary supplementation of copper nanoparticles (Cu-NPs) on growth, biochemical constituents, digestive enzyme activities, antioxidant, metabolic enzyme levels, and non specific immune response of the freshwater prawn, Macrobrachium rosenbergii post larvae (PL). The Cu-NPs (200 nm) were synthesized by facile and environmental friendly hydrothermal method. Cu-NPs were supplemented at 0, 10, 20, 40, 60, and 80 mg kg(-1) with the basal diets. These Cu-NPs supplemented diets were fed to M. rosenbergii PL for 90 days. Results showed significant (P<0.05) improvements were observed in survival, growth, digestive enzyme activities, concentrations of biochemical constituents and total and differential haemocytes count of prawns fed with 20 mg Cu-NPs kg(-1) supplemented feed. Prawns fed with 40-80 mg Cu-NPs kg(-1) supplemented feed showed negative performance. Activity of antioxidants and metabolic enzymes in the muscle and hepatopancreas of prawns showed no significant alterations (P>0.05) prawns fed with up to 20 mg Cu-NPs kg(-1) supplemented feeds. Whereas, prawns fed with 40-80 mg Cu-NPs kg(-1) supplemented feed showed significant (P<0.05) elevations in antioxidant and metabolic enzymes activities. Hence, 40-80 mg Cu-NPs kg(-1) diets may have toxic effect to M. rosenbergii. Hence, present study suggests that 20 mg Cu-NPs kg(-1) can be supplemented for regulating better survival, growth and immune response of M. rosenbergii PL.

In vitro study of the effect of metabolism enzymes on benzo(a)pyrene-induced DNA damage in the scallop Chlamys farreri

Acute toxicity effect of benzo(a)pyrene (BaP) on isolated scallop (Chlamys farreri) digestive gland cells was studied and a dose-dependent increase in toxicity was observed. The 8 μg/L of BaP had a significant toxic effect on isolated cells (p<0.05). In order to study the mechanism of CYP450, GST, SOD and MXR transporters involved in the production of DNA strand breakage such as DNA adduct formation and oxidative DNA damage by BaP were investigated in isolated digestive gland cells. Isolated cells were exposed in vitro to 0.8 μg/L of BaP for 24h in the dark at 25 °C in the absence or presence of cytochrome P450 inhibitor, GST inhibitor, Pgp inhibitor and antioxidant enzyme inhibitor. DNA adduct and 8-OHdG content were measured using the Enzyme-linked Immunosorbent Assay. The result indicated that DNA strand breakage was increased to 2 times compared with the control in the 0.8 μg/L of BaP treatment groups. The BaP-induced DNA adduct and 8-OHdG content increased significantly by inhibiting GST, while only 8-OHdG increased significantly when SOD was inhibited. The content of DNA adduct and 8-OHdG had no significant change when CYP450 was inhibited, while it decreased significantly when MXR transporters were inhibited. The result proved that GST play a key role in eliminating the BaP-induced DNA adduct and 8-OHdG, and SOD also had an important function in reducing the production of BaP-induced 8-OHdG.

Measuring cytochrome P450 activity in aquatic invertebrates: a critical evaluation of in vitro and in vivo methods

The first step in xenobiotic detoxification in aquatic invertebrates is mainly governed by the cytochrome P450 mixed function oxidase system. The ability to measure cytochrome P450 activity provides an important tool to understand macroinvertebrates' responses to chemical stressors. However, measurements of P450 activity in small aquatic invertebrates have had variable success and a well characterized assay is not yet available. The general lack of success has been scarcely investigated and it is therefore the focus of the present work. In particular, the suitability of the substrate selected for the assay, the sensitivity of the assay and the possible inhibition/attenuation of enzymatic activity caused by endogenous substances were investigated. 7-ethoxycoumarin-O-dealkylation activity of Daphnia magna, Chironomus riparius larvae and Hyalella azteca was assessed in vivo and in vitro and possible inhibition of enzymatic activity by macroinvertebrates homogenate was investigated. Activities of D. magna and C. riparius larvae measured in vivo were 1.37 ± 0.08 and 2.2 ± 0.2 pmol h(-1) organism(-1), respectively, while activity of H. azteca could not be detected. In vitro activity could be measured in C. riparius larvae only (500-1000 pmol h(-1) mg microsomal protein(-1)). The optimization of the in vitro assay has been especially long and resource consuming and particularly for D. magna, substances that inhibited cytochrome P450 activity seemed to be released during tissue homogenization preventing activity measurements in vitro. We therefore recommend testing the P450 inhibition potential of homogenate preparations prior to any investigation of P450 activity in vitro in macroinvertebrates.

Morphological and metabolic adjustments in the small intestine to energy demands of growth, storage, and fasting in the first annual cycle of a hibernating lizard (Tupinambis merianae)

Seasonal plasticity in the small intestine of neonatal tegu lizards was investigated using morphometry and analysis of enzymes involved in supplying energy to the intestinal tissue. In the autumn, the intestinal mass (Mi) was 1.0% of body mass and the scaling exponent b=0.92 indicated that Mi was larger in smaller neonates. During arousal from dormancy Mi was 23% smaller; later in spring, Mi increased 60% in relation to the autumn and the exponent b=0.14 indicated that the recovery was disproportionate in smaller tegus. During the autumn, the intestinal villi were greatly elongated; by midwinter, the Hv, SvEp, and VvEp were smaller than during the autumn (59%, 54%, 29%) and were restored to autumn levels during spring. In the active tegus, the maximum activity (Vmax) of enzymes indicated that the enterocytes can obtain energy from different sources, and possess gluconeogenic capacity. During winter, the Vmax of CS, HOAD, GDH, PEPCK was 40-50% lower in relation to the autumn and spring, while the Vmax of HK, PK, LDH, AST was unchanged. The hypoglycemia and the mucosal atrophy/ischemia during winter would prevent the enterocytes from using glucose, whereas they could slowly oxidize fatty acids released from body stores and amino acids from the tissue proteolysis to satisfy their needs of energy. Contrastingly, starvation during spring caused severe mass loss (50%); the tissue protein and the VvEp and VvLP did not change while the thickness of the muscular layer increased 51%, which suggested different effects along the length of the organ. In addition, the Vmax of the glycolytic enzymes was lower, indicating that a regulatory mechanism would spare blood glucose for vital organs during unanticipated food restriction.

Molecular changes in mitochondrial respiratory activity and metabolic enzyme activity in muscle of four pig breeds with distinct metabolic types

Skeletal muscles are metabolically active and have market value in meat-producing farm animals. A better understanding of biological pathways affecting energy metabolism in skeletal muscle could advance the science of skeletal muscle. In this study, comparative pathway-focused gene expression profiling in conjunction with muscle fiber typing were analyzed in skeletal muscles from Duroc, Pietrain, and Duroc-Pietrain crossbred pigs. Each breed type displayed a distinct muscle fiber-type composition. Mitochondrial respiratory activity and glycolytic and oxidative enzyme activities were comparable among genotypes, except for significantly lower complex I activity in Pietrain pigs homozygous-positive for malignant hyperthermia syndrome. At the transcriptional level, lactate dehydrogenase B showed breed specificity, with significantly lower expression in Pietrain pigs homozygous-positive for malignant hyperthermia syndrome. A similar mRNA expression pattern was shown for several subunits of oxidative phosphorylation complexes, including complex I, complex II, complex IV, and ATP synthase. Significant correlations were observed between mRNA expression of genes in focused pathways and enzyme activities in a breed-dependent manner. Moreover, expression patterns of pathway-focused genes were well correlated with muscle fiber-type composition. These results stress the importance of regulation of transcriptional rate of genes related to oxidative and glycolytic pathways in the metabolic capacity of muscle fibers. Overall, the results further the breed-specific understanding of the molecular basis of metabolic enzyme activities, which directly impact meat quality.

Assessing Natural Product-Drug Interactions: An End-to-End Safety Framework

The use of natural products (NPs), including herbal medicines and other dietary supplements, by North Americans continues to increase across all age groups. This population has access to conventional medications, with significant polypharmacy observed in older adults. Thus, the safety of the interactions between multi-ingredient NPs and drugs is a topic of paramount importance. Considerations such as history of safe use, literature data from animal toxicity and human clinical studies, and NP constituent characterization would provide guidance on whether to assess NP-drug interactions experimentally. The literature is replete with reports of various NP extracts and constituents as potent inhibitors of drug metabolizing enzymes, and transporters. However, without standard methods for NP characterization or in vitro testing, extrapolating these reports to clinically-relevant NP-drug interactions is difficult. This lack of a clear definition of risk precludes clinicians and consumers from making informed decisions about the safety of taking NPs with conventional medications. A framework is needed that describes an integrated robust approach for assessing NP-drug interactions; and, translation of the data into formulation alterations, dose adjustment, labelling, and/or post-marketing surveillance strategies. A session was held at the 41st Annual Summer Meeting of the Toxicology Forum in Colorado Springs, CO, to highlight the challenges and critical components that should be included in a framework approach.

Susceptibility profile of Aedes aegypti from Santiago Island, Cabo Verde, to insecticides

In 2009, Cabo Verde diagnosed the first dengue cases, with 21,137 cases reported and Aedes aegypti was identified as the vector. Since the outbreak, chemical insecticides and source reduction were used to control the mosquito population. This study aimed to assess the susceptibility of A. aegypti populations from Santiago, Cabo Verde to insecticides and identify the mechanisms of resistance. Samples of A. aegypti eggs were obtained at two different time periods (2012 and 2014), using ovitraps in different locations in Santiago Island to establish the parental population. F1 larvae were exposed to different concentrations of insecticides (Bacillus thuringiensis var israelensis (Bti), diflubenzuron and temephos) to estimate the lethal concentrations (LC90) and calculate the respective rate of resistance (RR90). Semi-field tests using temephos-ABATE(®) were performed to evaluate the persistence of the product. Bottle tests using female mosquitoes were carried out to determine the susceptibility to the adulticides malathion, cypermethrin and deltamethrin. Biochemical and molecular tests were performed to investigate the presence of metabolic resistance mechanisms, associated with the enzymes glutathione S-transferases (GSTs), esterases and mixed-function oxidases (MFO) and to detect mutations or alterations in the sodium channel and acetylcholinesterase genes. A. aegypti mosquitoes from Santiago exhibited resistance to deltamethrin, cypermethrin (mortality<80%) and temephos (RR90=4.4) but susceptibility to malathion (mortality≥98%), Bti and diflubenzuron. The low level of resistance to temephos did not affect the effectiveness of Abate(®). The enzymatic analysis conducted in 2012 revealed slight changes in the activities of GST (25%), MFO (18%), α-esterase (19%) and β-esterase (17%), but no significant changes in 2014. Target site resistance mutations were not detected. Our results suggest that the A. aegypti population from Santiago is resistant to two major insecticides used for vector control, deltamethrin and temephos. To our knowledge, this is the first report of temephos resistance in an African A. aegypti population. The low level of temephos resistance was maintained from 2012-2014, which suggested the imposition of selective pressure, although it was not possible to identify the resistance mechanisms involved. These data show that the potential failures in the local mosquito control program are not associated with insecticide resistance.

Joint toxicity of sediment-associated permethrin and cadmium to Chironomus dilutus: The role of bioavailability and enzymatic activities

Pyrethroid insecticides and metals commonly co-occurred in sediment and caused toxicity to benthic organisms jointly. To improve accuracy in assessing risk of the sediments contaminated by insecticides and metals, it is of great importance to understand interaction between the contaminants and reasons for the interaction. In the current study, permethrin and cadmium were chosen as representative contaminants to study joint toxicity of pyrethroids and metals to a benthic invertebrate Chironomus dilutus. A median effect/combination index-isobologram was applied to evaluate the interaction between sediment-bound permethrin and cadmium at three dose ratios. Antagonistic interaction was observed in the midges for all treatments. Comparatively, cadmium-dominated group (the ratio of toxicity contribution from permethrin and cadmium was 1:3) showed stronger antagonism than equitoxicity (1:1) and permethrin-dominated groups (3:1). The reasons for the observed antagonism were elucidated from two aspects, including bioavailability and enzymatic activity. The bioavailability of permethrin, expressed as the freely dissolved concentrations in sediment porewater and measured by solid phase microextraction, was not altered by the addition of cadmium, suggesting the change in permethrin bioavailability was not the reason for the antagonism. On the other hand, the activities of metabolic enzymes, glutathione S-transferase and carboxylesterase in the midges which were exposed to mixtures of permethrin and cadmium were significantly higher than those in the midges exposed to permethrin solely. Cadmium considerably enhanced the detoxifying processes of permethrin in the midges, which largely explained the observed antagonistic interaction between permethrin and cadmium.

Starvation beneficially influences the liver physiology and nutrient metabolism in Edwardsiella tarda infected red sea bream (Pagrus major)

Dietary compromises, especially food restrictions, possess species-specific effects on the health status and infection control in several organisms, including fish. To understand the starvation-mediated physiological responses in Edwardsiella tarda infected red sea bream, especially in the liver, we performed a 20-day starvation experiment using 4 treatment (2 fed and 2 starved) groups, namely, fed-placebo, starved-placebo, fed-infected, and starved-infected, wherein bacterial exposure was done on the 11th day. In the present study, the starved groups showed reduced hepatosomatic index and drastic depletion in glycogen storage and vacuole formation. The fed-infected fish showed significant (P<0.05) increase in catalase and superoxide dismutase activity in relation to its starved equivalent. Significant (P<0.05) alteration in glucose and energy metabolism, as evident from hexokinase and glucose-6-phosphate dehydrogenase activity, was recorded in the starved groups. Interestingly, coinciding with the liver histology, PPAR (peroxisome proliferator activated receptors) α transcription followed a time-dependent activation in starved groups while PPARγ exhibited an opposite pattern. The transcription of hepcidin 1 and transferrin, initially increased in 0dai (days after infection) starved fish but reduced significantly (P<0.05) at later stages. Two-color immunohistochemistry and subsequent cell counting showed significant increase in P63-positive cells at 0dai and 5dai but later reduced slightly at 10dai. Similar results were also obtained in the lysosomal (cathepsin D) and non-lysosomal (ubiquitin) gene transcription level. All together, our data suggest that starvation exerts multidirectional responses, which allows for better physiological adaptations during any infectious period, in red sea bream.

Resistance selection and molecular mechanisms of cypermethrin resistance in red hairy caterpillar (Amsacta albistriga walker)

Amsacta albistriga is one of the important pests of oilseed crops in India. This pest has developed high resistance to organophosphate (OP) insecticide in field. Therefore, cypermethrin insecticide was used as an alternative for this pest. After 20 generations of selection with cypermethrin, the LD50 value for A. albistriga was increased by 21.5-folds. The synergism ratio of piperonyl butoxide (PBO) and triphenyl phosphate (TPP) was increased by 10- and 9.6-fold in resistant strains and comparatively, 3.9 and 4.2-fold in susceptible strains. Detoxification enzyme analysis and native PAGE electrophoresis of esterase isoenzyme further revealed that esterase and mixed function oxidase may be involved in cypermethrin resistance in CypRes strain. In addition to enzyme analysis overexpression of CYP4M44, CYP9A77 and CYP6B47 (ortholog) can confer metabolic resistance in the CypRes strain. These data provide a foundation for further study of cypermethrin resistance mechanism observed in A. albistriga.

Effects of cadmium exposure on the gill proteome of Cottus gobio: modulatory effects of prior thermal acclimation

Temperature and trace metals are common environmental stressors, and their importance is increasing due to global climate change and anthropogenic pollution. The aim of the present study was to investigate whether acclimation to elevated temperature affects the response of the European bullhead (Cottus gobio) to subsequent cadmium (Cd) exposure by using enzymatic and proteomic approaches. Fish acclimated to 15 (standard temperature), 18 or 21 °C for 28 days were exposed to 1mg Cd/L for 4 days at the respective acclimation temperature. First, exposure to Cd significantly decreased the activity of the lactate dehydrogenase (LDH) in gills of fish acclimated to 15 or 18 °C. However, an acclimation to 21 °C suppressed the inhibitory effect of Cd. Second, using a proteomic analysis by 2D-DIGE, we observed that thermal acclimation was the first parameter affecting the protein expression profile in gills of C. gobio, while subsequent Cd exposure seemed to attenuate this temperature effect. Moreover, our results showed opposite effects of these two environmental stressors at protein expression level. From the 52 protein spots displaying significant interaction effects of temperature and Cd exposure, a total of 28 different proteins were identified using nano LC-MS/MS and the Peptide and Protein Prophet algorithms of Scaffold software. The identified differentially expressed proteins can be categorized into diverse functional classes, related to protein turnover, folding and chaperoning, metabolic process, ion transport, cell signaling and cytoskeleton. Within a same functional class, we further reported that several proteins displayed reverse responses following sequential exposure to heat and Cd. This work provides insights into the molecular pathways potentially involved in heat acclimation process and the interactive effects of temperature and Cd stress in ectothermic vertebrates.

Inhibition of MMP-2 expression affects metabolic enzyme expression levels: proteomic analysis of rat cardiomyocytes

In this study we examined the effect of inhibition of MMP-2 expression, using siRNA, on the cardiomyocyte proteome. Isolated cardiomyocytes were transfected with MMP-2 siRNA and incubated for 24h. Control cardiomyocytes from the same heart were transfected with scrambled siRNA following the same protocol. Comparison of control cardiomyocyte proteomes with proteomes from MMP-2 suppressed cardiomyocytes revealed 13 protein spots of interest (9 protein spots increased; 4 decreased). Seven protein spots were identified as mitochondrial enzymes involved in energy production and represent: ATP synthase beta subunit, dihydrolipoyllysine-residue succinyltransferase component of 2-oxoglutarate dehydrogenase complex, cytochrome c oxidase subunit 5A, electron transfer flavoprotein subunit beta, NADH dehydrogenase (ubiquinone) 1 alpha subcomplex subunit 5 and a fragment of mitochondrial precursor of long-chain specific acyl-CoA dehydrogenase. Furthermore, precursor of heat shock protein 60 and Cu-Zn superoxide dismutase were identified. Two protein spots corresponding to MLC1 were also detected. In addition, ATP synthase activity was measured and was increased by approximately 30%. Together, these results indicate that MMP-2 inhibition represents a novel cardioprotective therapy by promoting alterations in the levels of mitochondrial enzymes for improved energy metabolism and by preventing degradation of contractile proteins needed for normal excitation-contraction coupling.

BIOLOGICAL SIGNIFICANCE

During ischemia and reperfusion of cardiomyocytes, abnormality in excitation-contraction coupling and decreased energy metabolism often lead to myocardial infarction, but the cellular mechanisms are not fully elucidated. We show for the first time that intracellular inhibition of MMP-2 in cardiomyocytes increases contractility of aerobically perfused myocytes, which was accompanied by increased expression of contractile proteins (e.g., MLC-1). We also showed that MMP-2 inhibition produced a cardiomyocyte proteome that is consistent with improved mitochondrial energy metabolism (e.g., increased expression and activity of mitochondrial beta ATP synthase). Thus, MMP-2 appears to be involved in homeostatic regulation of protein turnover. Our results are significant since they point to targeting MMP-2 activity as a novel therapeutic option to limit myocardial damage by decreasing proteolytic degradation of mitochondrial metabolic enzymes and myocardial contractile proteins during ischemia. In addition, the development of novel pharmacological agents that selectively targets cardiac MMP-2 represents a novel approach to treat and prevent other heart diseases.

The Kunitz-protease inhibitor domain in amyloid precursor protein reduces cellular mitochondrial enzymes expression and function

Mitochondrial dysfunction is a prominent feature of Alzheimer's disease (AD) and this can be contributed by aberrant metabolic enzyme function. But, the mechanism causing this enzymatic impairment is unclear. Amyloid precursor protein (APP) is known to be alternatively spliced to produce three major isoforms in the brain (APP695, APP751, APP770). Both APP770 and APP751 contain the Kunitz Protease Inhibitory (KPI) domain, but the former also contain an extra OX-2 domain. APP695 on the other hand, lacks both domains. In AD, up-regulation of the KPI-containing APP isoforms has been reported. But the functional contribution of this elevation is unclear. In the present study, we have expressed and compared the effect of the non-KPI containing APP695 and the KPI-containing APP751 on mitochondrial function. We found that the KPI-containing APP751 significantly decreased the expression of three major mitochondrial metabolic enzymes; citrate synthase, succinate dehydrogenase and cytochrome c oxidase (COX IV). This reduction lowers the NAD(+)/NADH ratio, COX IV activity and mitochondrial membrane potential. Overall, this study demonstrated that up-regulation of the KPI-containing APP isoforms is likely to contribute to the impairment of metabolic enzymes and mitochondrial function in AD.

Metabolic changes in the lower esophageal sphincter influencing the result of anti-reflux surgical interventions in chronic gastroesophageal reflux disease

AIM: With the availability of a minimally invasive approach, anti-reflux surgery has recently experienced a renaissance as a cost-effective alternative to life-long medical treatment in patients with gastroesophageal reflux disease (GERD). We are not aware of the fact whether reflux episodes causing complaints for a long time i.e., at least for one year are associated with metabolic changes in the lower esophageal sphincter, and if so, whether these may influence functional results achieved after anti-reflux surgery.

METHODS: Between 1 January 2001 and 31 December 2002 we performed anti-reflux surgery on 79 patients. Muscle samples were taken from the lower esophageal sphincter (LES) in 33 patients during anti-reflux surgery. Inclusion criteria were: LES resting pressure below 10 mmHg and a marked, pH proven acid exposure to the esophagus of at least one year’ duration, causing subjective complaints and requiring continuous proton pump inhibitor treatment. Control samples were obtained from muscle tissue in the gastroesophageal junction that had been removed from 17 patients undergoing gastric or esophageal resection. Metabolic and lysosomal enzyme activities and special protein concentrations 16 parameters in total were evaluated in tissue taken from control specimens and tissue taken from patients with GERD. The biochemical parameters of these intra-operative biopsies were used to correlate the results of anti-reflux operations (Visick I and II-III).

RESULTS: In the reflux-type muscle, we found a significant increase of the energy-enzyme activities e.g., creatine kinase, lactate dehydrogenase, β-hydroxybutyrate dehydrogenase, and aspartate aminotransaminase-. The concentration of the structural protein S-100 and the myofibrillar protein troponin I were also significantly increased. Among lysosomal enzymes, we found that the activities of cathepsin B, tripeptidyl-peptidase I, dipeptidyl-peptidase II, β-hexosaminidase B, β-mannosidase and β-galactosidase were significantly decreased as compared to the control LES muscles. By analyzing the activity values of the 9 patients in Visick groups II and III at two months post-surgery, we found a significant increase in the activity of the so-called energy-enzyme values and in the concentration of structural and myofibrillar proteins as compared to the rest of the reflux patients.

CONCLUSION: Our results call attention to the metabolic changes that occurred in the LES muscles of reflux patients. The developing hypertrophy-like changes of LES muscles may be a reason for complaints after anti-reflux surgery, which consisted mainly of reports of persisting dysphagia.