Enzymes Of Glucose Metabolism Research Articles

Effects of Dietary Carbohydrate Sources on Growth Performance, Glucose Metabolism, and Digestive Enzyme Activity of Litopenaeus vannamei

This study evaluated the effects of different sources of dietary carbohydrates on the growth, antioxidant capacity, and digestive enzyme activity, and carbohydrate metabolic enzyme activity of Litopenaeus vannamei were evaluated. The experimental diets, including glucose, sucrose, potato starch, corn starch, and wheat starch, were fed to L. vannamei for 35 days. We found that shrimp fed on corn starch and wheat starch grew better, whereas shrimp fed on wheat starch showed the highest digestive enzyme activity. In addition, the starch group showed higher total superoxide dismutase (T-SOD) activity and lower malondialdehyde (MDA) content. The glucose, sucrose, starch, and corn starch fed shrimp showed significantly higher levels of hepatopancreatic hexokinase (HK), whereas those fed on glucose and potato starch also showed significantly higher levels of hepatopancreatic phosphofructokinase (PFK) activity. The activities of phosphoenolpyruvate carboxykinase (PEPCK) and glucose 6-phosphatase (G6Pase) were higher in shrimp fed on glucose, whereas higher fructose 1,6-bisphosphatase (FBPase) activity was observed in shrimp fed on wheat starch, glucose, and sucrose. The insulin content of shrimp in the glucose group and potato starch group was higher, whereas that of the glucose group was higher than that of the potato starch group. In brief, the addition of wheat starch to the diet plays a positive role in the growth, glycolysis, gluconeogenesis, and antioxidant activity of shrimp, and is a promising choice for juvenile shrimp culture.

Impact of Glyphosate on the Development of Insulin Resistance in Experimental Diabetic Rats: Role of NFκB Signalling Pathways.

Glyphosate, an endocrine disruptor, has an adverse impact on human health through food and also has the potential to produce reactive oxygen species (ROS), which can lead to metabolic diseases. Glyphosate consumption from food has been shown to have a substantial part in insulin resistance, making it a severe concern to those with type 2 diabetes (T2DM). However, minimal evidence exists on how glyphosate impacts insulin-mediated glucose oxidation in the liver. Hence the current study was performed to explore the potential of glyphosate toxicity on insulin signaling in the liver of experimental animals. For 16 weeks, male albino Wistar rats were given 50 mg, 100 mg and 250 mg/kg b. wt. of glyphosate orally. In the current study, glyphosate exposure group was linked to a rise in fasting sugar and insulin as well as a drop in serum testosterone. At the same time, in a dose dependent fashion, glyphosate exposure showed alternations in glucose metabolic enzymes. Glyphosate exposure resulted in a raise in H2O2 formation, LPO and a reduction in antioxidant levels those results in impact on membrane integrity and insulin receptor efficacy in the liver. It also registered a reduced levels of mRNA and protein expression of insulin receptor (IR), glucose transporter-2 (GLUT2) with concomitant increase in the production of proinflammatory factors such as JNK, IKKβ, NFkB, IL-6, IL-1β, and TNF-α as well as transcriptional factors like SREBP1c and PPAR-γ leading to pro-inflammation and cirrhosis in the liver which results in the development of insulin resistance and type 2 diabetes. Our present findings for the first time providing an evidence that exposure of glyphosate develops insulin resistance and type 2 diabetes by aggravating NFkB signaling pathway in liver.

Glucose-6-Phosphate Dehydrogenase, ZwfA, a Dual Cofactor-Specific Isozyme Is Predominantly Involved in the Glucose Metabolism of Pseudomonas bharatica CSV86T.

Glucose-6-phosphate dehydrogenase (Zwf) is an important enzyme in glucose metabolism via the Entner-Doudoroff pathway and the first enzyme in the oxidative pentose-phosphate pathway. It generates NAD(P)H during the conversion of glucose-6-phosphate (G6P) to 6-phosphogluconolactone, thus aiding in anabolic processes, energy yield, and oxidative stress responses. Pseudomonas bharatica CSV86T preferentially utilized aromatic compounds over glucose and exhibited a significantly lower growth rate on glucose (0.24 h-1) with a prolonged lag phase (~10 h). In strain CSV86T, glucose was metabolized via the intracellular phosphorylative route only because it lacked an oxidative (gluconate and 2-ketogluconate) route. The genome harbored three genes zwfA, zwfB, and zwfC encoding three Zwf isozymes. The present study aimed to understand gene arrangement, gene expression profiling, and molecular and kinetic properties of the purified enzymes to unveil their physiological significance in the strain CSV86T. The zwfA was found to be a part of the zwfA-pgl-eda operon, which was proximal to other glucose transport and metabolic clusters. The zwfB was found to be arranged as a gnd-zwfB operon, while zwfC was present independently. Among the three, zwfA was transcribed maximally, and the purified ZwfA displayed the highest catalytic efficiency, cooperativity with respect to G6P, and dual cofactor specificity. Isozymes ZwfB and ZwfC were NADP+-preferring and NADP+-specific, respectively. Among other functionally characterized Zwfs, ZwfA from strain CSV86T displayed poor catalytic efficiency and the further absence of oxidative routes of glucose metabolism reflected its lower growth rate on glucose compared to P. putida KT2440 and could be probable reasons for the unique carbon source utilization hierarchy. IMPORTANCE Pseudomonas bharatica CSV86T metabolizes glucose exclusively via the intracellular phosphorylative Entner-Doudoroff pathway leading the entire glucose flux through Zwf as the strain lacks oxidative routes. This may lead to limiting the concentration of downstream metabolic intermediates. The strain CSV86T possesses three isoforms of glucose-6-phosphate dehydrogenase, ZwfA, ZwfB, and ZwfC. The expression profile and kinetic properties of purified enzymes will help to understand glucose metabolism. Isozyme ZwfA dominated in terms of expression and displayed cooperativity with dual cofactor specificity. ZwfB preferred NADP+, and ZwfC was NADP+ specific, which may aid in redox cofactor balance. Such beneficial metabolic flexibility facilitated the regulation of metabolic pathways giving survival/fitness advantages in dynamic environments. Additionally, multiple genes allowed the distribution of function among these isoforms where the primary function was allocated to one of the isoforms.

Elevated protein O-GlcNAcylation is associated with change of glucose metabolism enzyme levels and their link to nNOS in Alzheimer’s disease postmortem brains

Elevated protein O-GlcNAcylation is associated with change of glucose metabolism enzyme levels and their link to nNOS in Alzheimer’s disease postmortem brains

Response of sugar metabolism in the cotyledons and roots of Ricinus communis subjected to salt stress.

Ricinus communis is an important oilseed crop worldwide and is also considered one of the best potential plants for salt-affected soil improvement in northeast China. However, little is known about photosynthesis and carbohydrate metabolism in this plant, nor the distribution of carbohydrates in cotyledons and roots under salinity stress. In the present study, seedling growth, gas exchange parameters (PN , E, gs and Ci ), carbohydrate (fructose, sucrose, glucose, soluble sugar and starch) metabolism and related enzymes and genes were measured in Ricinus plants. Under salt stress, PN of cotyledons decreased significantly (P< 0.05), resulting in weak photosynthetic capacity. Furthermore, salt stress increased sucrose and glucose content in cotyledons, but decreased soluble sugar and starch content. However, sucrose increased and starch decreased in roots. This may be correlated with the increasing sugar metabolism under salinity, including notable changes in sugar-related enzyme activities (SPS, SuSy, α-amylase and β-amylase) and gene expression of RcINV, RcSUS, RcAmY, RcBAM and RcGBE1. The results suggest that salinity reduces photosynthesis of cotyledons, alters carbohydrate allocation between cotyledons and roots and also promotes starch utilization in cotyledons and starch biosynthesis in roots, leading to a functional imbalance between cotyledons and roots. Together, these findings provide insights into the crucial role of sugar metabolism in improving salt-tolerance of Ricinus during the early seedling growth stage.

Intermittent fasting and exercise therapy abates STZ-induced diabetotoxicity in rats through modulation of adipocytokines hormone, oxidative glucose metabolic, and glycolytic pathway.

Diabetes is a global, costly, and growing public health issue. Intermittent fasting (IF) and exercise therapy have been shown to improve insulin sensitivity (IS) in large studies, although the underlying processes are still unknown. The goal of this study, which included both nondiabetic and diabetic rats, was to look at the mechanisms of intermittent fasting and exercise in the management of diabetotoxicity. The effects of starvation and honey on the oral glucose tolerance test, insulin tolerance test, adipocytokines, oxidative glucose metabolic enzymes, glycolytic enzymes, food intake, and body weight in rats with streptozotocin-induced diabetes were also investigated. In the nondiabetic phase, rats were administered an oral regimen of distilled water (0.5ml/rat), honey (1g/kg body weight), and interventions with IF, and starvation for 4weeks while in the diabetic phase, after STZ or citrate buffer injections, interventions with IF, exercise, starvation, and honey treatment began for 4weeks. At all OGTT and ITT points, there was a substantial rise in glucose in the STZ group. Adipocytokines hormone, oxidative glucose metabolic enzymes, glycolytic enzymes, and body weight were all affected by STZ when compared to starvation and honey, however, IF and exercise significantly reduced these alterations. In diabetic rats, intermittent fasting and exercise enhanced serum adipocytokines levels. These findings imply that adipokines modulate glycolytic/nonmitochondrial enzymes and glucose metabolic/mitochondrial dehydrogenase to mediate the antidiabetic effects of intermittent fasting and exercise.

PHA stimulated denitrification through regulation of preferential cofactor provision and intracellular carbon metabolism at different dissolved oxygen levels by Pseudomonas stutzeri

Denitrification, a typical biological process mediated by complex environmental factors, i.e., carbon sources and dissolved oxygen (DO), has attracted great attention due to its contribution to the control of eutrophication and the biochemical cycling of nitrogen. However, the effects of carbon source on electron distribution and enzyme expression for enhanced denitrification under competition of electron acceptors (DO and nitrate) remain unclear. Here, we profile the carbon metabolic pathway of polyhydroxybutyrate (PHB) and glucose (Glu) at high and low DO levels (50% and 10% saturated DO, respectively). It was found that PHB enhanced the growth of Pseudomonas stutzeri (model denitrifying bacterium) and improved the specific nitrogen removal rate (SNRR) at all DO levels. The functional proteins had a better affinity for the cofactor nicotinamide-adenine dinucleotide (NADH) than for nicotinamide adenine dinucleotide phosphate (NADPH); thus, more electrons were involved in nitrogen reduction and intracellular PHB production in the PHB groups than in the Glu groups. Furthermore, the expression difference of enzymes in glucose and PHB metabolism was demonstrated by metaproteomic and target protein analysis, implying that PHB-driven intracellular carbon accumulation could optimize the intracellular electron allocation and correspondingly promote nitrogen metabolism. Our work integrated the mechanisms of intracellular carbon metabolism with preferences for electron transfer pathways in denitrification, providing a new perspective on how the selective parameters regulated microbial functions involved in denitrification.

Targeting Glucose Metabolism Enzymes in Cancer Treatment: Current and Emerging Strategies.

Simple SummaryReprogramming of glucose metabolism is a hallmark of cancer and can be targeted by therapeutic agents. Some metabolism regulators, such as ivosidenib and enasidenib, have been approved for cancer treatment. Currently, more advanced and effective glucose metabolism enzyme-targeted anticancer drugs have been developed. Furthermore, some natural products have shown efficacy in killing tumor cells by regulating glucose metabolism, offering novel therapeutic opportunities in cancer. However, most of them have failed to be translated into clinical applications due to low selectivity, high toxicity, and side effects. Recent studies suggest that combining glucose metabolism modulators with chemotherapeutic drugs, immunotherapeutic drugs, and other conventional anticancer drugs may be a future direction for cancer treatment.Reprogramming of glucose metabolism provides sufficient energy and raw materials for the proliferation, metastasis, and immune escape of cancer cells, which is enabled by glucose metabolism-related enzymes that are abundantly expressed in a broad range of cancers. Therefore, targeting glucose metabolism enzymes has emerged as a promising strategy for anticancer drug development. Although several glucose metabolism modulators have been approved for cancer treatment in recent years, some limitations exist, such as a short half-life, poor solubility, and numerous adverse effects. With the rapid development of medicinal chemicals, more advanced and effective glucose metabolism enzyme-targeted anticancer drugs have been developed. Additionally, several studies have found that some natural products can suppress cancer progression by regulating glucose metabolism enzymes. In this review, we summarize the mechanisms underlying the reprogramming of glucose metabolism and present enzymes that could serve as therapeutic targets. In addition, we systematically review the existing drugs targeting glucose metabolism enzymes, including small-molecule modulators and natural products. Finally, the opportunities and challenges for glucose metabolism enzyme-targeted anticancer drugs are also discussed. In conclusion, combining glucose metabolism modulators with conventional anticancer drugs may be a promising cancer treatment strategy.

Comparative effect of a nutraceutical compound based on a flavonoid complex from bergamot on plasma lipids, glucose metabolism, and liver enzymes: a 3-arm, double-blind, placebo-controlled, randomized clinical trial.

Bergamot and opuntia (prickly pear cladodes) standardized extracts have been demonstrated to have positive metabolic effects in preclinical and clinical models. The aim of this study was to evaluate the metabolic effect of a combined nutraceutical containing 150 mg of Opuntia ficus Indica extract, 400 mg of plant sterols, 12.5 mg of thiamine, and 200 mg of Brumex® a phytocomplex from bergamot fruit (Citrus bergamia Risso et Poiteau, fructus) standardized 40% in total flavonoids and min 5% in 3-hydroxy-3-methylglutaryl-flavanones. Thus, we carried out a randomized, double-blind, placebo-controlled clinical trial on 75 hypercholesterolaemic subjects randomized to take the active compound (2 tablets per day), placebo (2 tablets per day), or both (1 per product per day). After 12 weeks of treatment with 1 tablet per day, we observed a significant reduction of a number of metabolic parameters: total cholesterol (TC) (-14.6%), low-density lipoprotein cholesterol (LDL-C) (-19.9%), non-high-density lipoprotein cholesterol (non-HDLC) (-22.1%), triglycerides (TG) (-13.1%), Apolipoprotein B (-16%) (all p < 0.05 both versus baseline and versus placebo), fasting plasma glucose (-5.1%), glutamate oxaloacetate transaminase (-7.8%), glutamate pyruvate transaminase (-7.3%), and γ-glutamyl transferase (-34.4%) (all p < 0.05 versus baseline). High-density lipoprotein cholesterol (HDL-C) was increased 6.9% by the use of 1 tablet per day (p < 0.05 versus baseline). All parameters were reduced to the same extent when taking the full dose (2 tablets), beyond TG. the tested nutraceutical compound based on a flavonoid complex from bergamot and opuntia showed a short-term positive impact on plasma lipids, fasting plasma glucose, and liver enzyme in overall healthy subjects affected by hypercholesterolaemia with low cardiovascular risk.

ERK1/2-Dependent Inhibition of Glycolysis in Curcumin-Induced Cytotoxicity of Prostate Carcinoma Cells.

Methods Cell viability, glycolytic activity, Annexin V-PE binding activity, reactive oxygen species levels, mitochondrial membrane potential, ATP content, Western blot analysis, and spheroid viability were measured for this study. Results Acidic pH-tolerant prostate cancer cells, PC-3AcT and DU145AcT, increased cytotoxicity with ERK1/2 inhibition in a curcumin concentration-dependent manner at concentrations that resulted in >90% cell viability in normal prostate epithelial HPrEC cells. ERK1/2 inhibition by curcumin and/or PD98059 suppressed cell growth, reduced glucose consumption, and downregulated the expression of key regulatory enzymes in glucose metabolism including hexokinases, phosphofructokinase, and pyruvate dehydrogenase. In addition, these compounds caused loss of mitochondrial membrane potential with increased intracellular ROS levels, decreased levels of complexes I, III, and IV in the mitochondrial electron transport chain, and cellular ATP depletion, leading to upregulation of marker proteins in apoptosis (cleaved caspase-3 and cleaved PARP) and necroptosis (p-MLKL and p-RIP3). The results of curcumin and/or PD98059 treatment in 3D cultures showed similar trends to those in 2D cultures. Conclusion Taken together, the results provide mechanistic evidence for the antiglycolytic and cytotoxic roles of curcumin through inhibition of the MEK/ERK signaling pathway in prostate carcinoma cells preadapted to acidic conditions.

Chronic social stress disrupts the intracellular redistribution of brain hexokinase 3 induced by shifts in peripheral glucose levels

Chronic stress has the potential to impair health and may increase the vulnerability for psychiatric disorders. Emerging evidence suggests that specific neurometabolic dysfunctions play a role herein. In mice, chronic social defeat (CSD) stress reduces cerebral glucose uptake despite hyperglycemia. We hypothesized that this metabolic decoupling would be reflected by changes in contact sites between mitochondria and the endoplasmic reticulum, important intracellular nutrient sensors, and signaling hubs. We thus analyzed the proteome of their biochemical counterparts, mitochondria-associated membranes (MAMs) from whole brain tissue obtained from CSD and control mice. This revealed a lack of the glucose-metabolizing enzyme hexokinase 3 (HK3) in MAMs from CSD mice. In controls, HK3 protein abundance in MAMs and also in striatal synaptosomes correlated positively with peripheral blood glucose levels, but this connection was lost in CSD. We conclude that the ability of HK3 to traffic to sites of need, such as MAMs or synapses, is abolished upon CSD and surmise that this contributes to a cellular dysfunction instigated by chronic stress.Key messagesChronic social defeat (CSD) alters brain glucose metabolismCSD depletes hexokinase 3 (HK3) from mitochondria-associated membranes (MAMs)CSD results in loss of positive correlation between blood glucose and HK3 in MAMs and synaptosomes

Differential role of neuronal glucose and PFKFB3 in memory formation during development.

The consumption of glucose in the brain peaks during late childhood; yet, whether and how glucose metabolism is differentially regulated in the brain during childhood compared to adulthood remains to be understood. In particular, it remains to be determined how glucose metabolism is involved in behavioral activations such as learning. Here we show that, compared to adult, the juvenile rat hippocampus has significantly higher mRNA levels of several glucose metabolism enzymes belonging to all glucose metabolism pathways, as well as higher levels of the monocarboxylate transporters MCT1 and MCT4 and the glucose transporters endothelial-GLUT1 and GLUT3 proteins. Furthermore, relative to adults, long-term episodic memory formation in juvenile animals requires significantly higher rates of aerobic glycolysis and astrocytic-neuronal lactate coupling in the hippocampus. Only juvenile but not adult long-term memory formation recruits GLUT3, neuronal 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) and more efficiently engages glucose in the hippocampus. Hence, compared to adult, the juvenile hippocampus distinctively regulates glucose metabolism pathways, and formation of long-term memory in juveniles involves differential neuronal glucose metabolism mechanisms.

Luteolin-Rich Extract of Thespesia garckeana F. Hoffm. (Snot Apple) Contains Potential Drug-Like Candidates and Modulates Glycemic and Oxidoinflammatory Aberrations in Experimental Animals.

The present study evaluated the polyphenolic contents and hypoglycemic, antioxidant, and anti-inflammatory effects of the diethyl ether fraction of Thespesia garckeana using various in vitro and in vivo models. Total phenol and flavonoid contents of the extract were 613.65 ± 2.38 and 152.83 ± 1.56 mg/100 g dry weight, respectively. The extract exhibited in vitro antioxidant activities against DPPH, FRAP, LPO, and ABTS with respective half-maximal inhibitory concentration (IC50) values of 30.91 ± 0.23, 16.81 ± 0.51, 41.29 ± 1.82, and 42.39 ± 2.24 μg/mL. In vitro anti-inflammatory studies using membrane stabilization, protein denaturation, and proteinase activities revealed the effectiveness of the extract with respective IC50 values of 54.45 ± 2.89, 93.62 ± 3.04, and 56.60 ± 2.34 μg/mL, while in vitro hypoglycemic analysis of the extract revealed inhibition of α-amylase (IC5064.59 ± 3.29 μg/mL) and enhancement of glucose uptake by yeast cells. Interestingly, the extract demonstrated in vivo hypoglycemic and anti-inflammatory effects in streptozotocin- (STZ-) induced diabetic and xylene-induced ear swelling models, respectively. In addition, the extract improved insulin secretion, attenuated pancreatic tissue distortion and oxidative stress, and increased the activities of superoxide dismutase (SOD), catalase, and reduced glutathione (GSH), while reducing the concentration of LPO in the diabetic rats. A high-performance liquid chromatography (HPLC) analysis identified the presence of catechin (6.81e − 1 ppm), rutin (8.46 e − 1 ppm), myricetin, apigenin (4.019 e − 1 ppm), and luteolin (15.09 ppm) with respective retention times (RTs) of 13.64, 24.269, 27.781, 29.58, and 32.23 min, and these were subjected to a pharmacoinformatics analysis, which revealed their drug-likeness and good pharmacokinetic properties. A docking analysis hinted at the potential of luteolin, the most abundant compound in the extract, for targeting glucose-metabolizing enzymes. Thus, the present study provides preclinical insights into the bioactive constituents of T. garckeana, its antioxidant and anti-inflammatory effects, and its potential for the treatment of diabetes.

Isolation and Characterisation of Hordatine-Rich Fractions from Brewer’s Spent Grain and Their Biological Activity on α-Glucosidase and Glycogen Phosphorylase α

Hordatines are a characteristic class of secondary metabolites found in barley which have been reported to be present in barley malt, beer and, recently, brewer´s spent grain (BSG). However, little is known about their biological activities such as antioxidative effects in beer or antifungal activity as their main task within the plants. We conducted an in vitro investigation of the activity of hordatines isolated from BSG towards enzymes of glucose metabolism. Hordatine-rich fractions from BSG were prepared by solid-liquid extraction (SLE) with 60% acetone followed by purification and fractionation. The fractions were characterised and investigated for their in vitro inhibitory potential on α-glucosidase and glycogen phosphorylase α (GPα). Both enzymes are relevant within the human glucose metabolism regarding the digestion of carbohydrates as well as the liberation of glucose from the liver. In total, 10 hordatine-rich fractions varying in the composition of different hordatines were separated and analysed by mass spectrometry. Hordatine A, B and C, as well as hydroxylated aglycons and many glycosides, were detected in the fractions. The total hordatine content was analysed by HPLC-DAD using a semi-quantitative approach and ranged from 60.7 ± 3.1 to 259.6 ± 6.1 µg p-coumaric acid equivalents/mg fraction. Regarding the biological activity of fractions, no inhibitory effect on GPα was observed, whereas an inhibitory effect on α-glucosidase was detected (IC50 values: 77.5 ± 6.5–194.1 ± 2.6 µg/mL). Overall, the results confirmed that hordatines are present in BSG in relatively high amounts and provided evidence that they are potent inhibitors of α-glucosidase. Further research is needed to confirm these results and identify the active hordatine structure.

Natural Sources, Pharmacological Properties, and Health Benefits of Daucosterol: Versatility of Actions

Daucosterol is a saponin present in various natural sources, including medicinal plant families. This secondary metabolite is produced at different contents depending on species, extraction techniques, and plant parts used. Currently, daucosterol has been tested and explored for its various biological activities. The results reveal potential pharmacological properties such as antioxidant, antidiabetic, hypolipidemic, anti-inflammatory, immunomodulatory, neuroprotective, and anticancer. Indeed, daucosterol possesses important anticancer effects in many signaling pathways, such as an increase in pro-apoptotic proteins Bax and Bcl2, a decrease in the Bcl-2/Bax ratio, upregulation of the phosphatase and tensin homolog (PTEN) gene, inhibition of the PI3K/Akt pathway, and distortion of cell-cycle progression and tumor cell evolution. Its neuroprotective effect is via decreased caspase-3 activation in neurons and during simulated reperfusion (OGD/R), increased IGF1 protein expression (decreasing the downregulation of p-AKT3 and p-GSK-3b4), and activation of the AKT5 signaling pathway. At the same time, daucosterol inhibits key glucose metabolism enzymes to keep blood sugar levels within normal ranges. Therefore, this review describes the principal research on the pharmacological activities of daucosterol and the mechanisms of action underlying some of these effects. Moreover, further investigation of pharmacodynamics, pharmacokinetics, and toxicology are suggested.

Flurochloridone induces responses of free radical reactions and energy metabolism disorders to BRL-3A cell

Flurochloridone (FLC), a wildly used herbicide, could induce hepatotoxicity after long-term exposure to male rat, in addition to its reactive oxygen species (ROS)-dependent reproductive toxicity. The hepatotoxicity effect and mechanism was investigeted using 1, 10 and 100 μmol L−1 FLC treated BRL-3A liver cell in this study. The function of mitochondrial respiration, glycolysis rate and real time ATP production rate are determined by seahorse XF analyzer, and the bio-transformers of FLC, intermediates of TCA cycle and glycolysis, and related amino acids are determined and identified by [U-13C] Glucose metabolic flux technology based on UPLC-HRMS. The mRNA expression of cytochrome P450s and the key regulatory enzymes of glucose metabolism and γ- glutamyl cycle pathway. The protein expressions of protein kinase B (AKT) and glycogen synthase kinase-3 beta (GSK-3β) were determined. The results show dechlorination and glutathione (GSH) conjugate products of FLC are predominant bio-transformmers after 24 h treatment in BRL-3A cell. FLC could enhance glycolysis function and inhibit mitochondrial aerobic respiratory, which is accompanied by the decreased total ATP level and ATP produced rate. Increased glucose-6-phosphate, fructose-6-phosphate, pyruvate and lactate levels, and elevated level of GSH and its precursor 5-glutamate-cysteine (γ-Glu-Cys) are observed in FLC treated cells, which indicates that energy metabolism dysfunction and GSH accumulation could be potentially mediated by activating γ- Glutamyl cycle pathway. Conclusively, FLC induced hepatotoxicity could be potentially related to some free radical reactions, including inhibiting mitochondrial function, glucose metabolism via glycolysis, regulating γ- glutamyl cycle pathway to promote reactive oxygen species (ROS) level, and then induced cell apoptosis by inhibiting AKT/GSK-3β signal.

Lactate Dehydrogenase B Is Required for Pancreatic Cancer Cell Immortalization Through Activation of Telomerase Activity.

Telomerase activity is elevated in most cancer cells and is required for telomere length maintenance and immortalization of cancer cells. Glucose metabolic reprogramming is a hallmark of cancer and accompanied with increased expression of key metabolic enzymes. Whether these enzymes influence telomerase activity and cell immortalization remains unclear. In the current study, we screened metabolic enzymes using telomerase activity assay and identified lactate dehydrogenase B (LDHB) as a regulator of telomerase activity. Sodium lactate and sodium pyruvate did not influence telomerase activity, indicating LDHB regulates telomerase activity independent of its metabolism regulating function. Further studies revealed that LDHB directly interacted with TERT and regulated the interaction between TERT and TERC. Additionally, long-term knockdown of LDHB inhibited cancer cell growth and induced cell senescence in vitro and in vivo. Higher LDHB expression was detected in pancreatic cancer tissues compared with that in adjacent normal tissues and expression of LDHB correlated negatively with prognosis. Thus, we identified LDHB as the first glucose metabolic enzyme contributing to telomerase activity and pancreatic cancer cell immortalization.

Effects of BBR on growth performance, serum and hepatic biochemistry parameters, hepatic morphology and gene expression levels related to glucose metabolism in largemouth bass, Micropterus salmoides

An 8-week experiment was performed to investigate the effects of BBR on growth performance, hepatic glucose metabolism, antioxidant capacity, liver histology and intestinal digestive enzyme activity of largemouth bass. Fish (initial weight ≈122 g) were randomly allocated into 16 cages (280 L, 30 fish per tank) and fed four isonitrogenous and isolipidic diets containing 0, 0.5, 1 and 2 g/kg BBR respectively. The results indicated that diets with 1 and 2 g/kg BBR significantly promoted growth, decreased serum glucose, triglycerides (TG), total cholesterol (TC) and low-density lipoprotein cholesterol but increased serum high-density lipoprotein cholesterol (p < 0.05). The application of BBR significantly decreased hepatic alanine aminotransferase, TG and TC but increased hepatic superoxide dismutase and catalase (p < 0.05). Diets with 1 and 2 g/kg BBR significantly decreased hepatic malondialdehyde, aspartate aminotransferase and hepatic glycogen but increased intestinal farnesoid X receptor and fibroblast growth factor-19 expression and dramatically altered its downstream glycolysis- and gluconeogenesis-related genes, along with their enzyme activities (p < 0.05). Supplementation with BBR increased (p < 0.05) intestinal protease activity in B5, B10 and B20, lipase activity in B10 and B20 and amylase activity in B20. BBR reduced the liver voiding rate and fat content. These results indicated that dietary supplementation with BBR at 1 and 2 g/kg was beneficial for promoting growth and health in largemouth bass. The improved glycolysis and inhibited gluconeogenesis may account for the reduced hyperglycaemia by BBR. In addition, enhancing the activity of intestinal digestive enzymes is an effective way for BBR to improve carbohydrate utilization in largemouth bass.

Dual Inhibitions on Glucose/Glutamine Metabolisms for Nontoxic Pancreatic Cancer Therapy.

Glucose and glutamine are two principal nutrients in mammalian cells that provide energy and biomass for cell growth and proliferation. Especially in cancer cells, glutamine could be a main alternative for energy and biomass supply once glucose metabolism is suppressed. Therefore, single inhibition of enzymes in either glucose metabolism or glutaminolysis, though maybe efficient in vitro, is far from being satisfactory for efficient in vivo cancer therapy. Here, we proposed a new strategy for dual inhibitions on both glucose and glutamine metabolisms concurrently by silencing mutated gene Kras and glutaminase 1 (GLS1) via nanomaterial-based siKras and siGLS1 delivery, rather than conventional highly toxic chemodrugs. Such a combination therapy could overcome the challenge that glucose and glutamine are alternatives to each other in the biosynthesis and energy production for cancer cells, resulting in much elevated treatment efficacy. In addition, layered double hydroxide (LDH), the siRNA carrier, enables an enhanced gene delivery efficiency compared to the commercial transfection agent Lipofectamine 2000. Briefly, Mg-Al LDH nanosheets, loaded with siKras and siGLS1 onto their surfaces by electrostatic adsorption, could release siRNA from lysosomes into the cytoplasm via the proton sponge effect of LDH, favoring the siRNA stability and gene silencing efficiency enhancements. The thus released siRNA could downregulate the expressions of Kras, GLS1, and other enzymes involved in glucose metabolism, resulting in the downregulations of ATP and other metabolites. Such a biosafe LDH/siRNA nanomedicine is able to efficiently suppress the growth of xenografts through cancer cell proliferation suppression, displaying its great potential as a simultaneous glucose/glutamine metabolism coinhibitor for treating pancreatic cancer.

LncRNA-DANCR Promotes Taxol Resistance of Prostate Cancer Cells through Modulating the miR-33b-5p-LDHA Axis.

Prostate cancer (PCa) is one of the most common malignancies in men with high death rate worldwide. Paclitaxel (Taxol) is a widely used anticancer agent. Despite recent improvements in clinical application and research, development of drug resistance limits the efficacy of the Taxol-based chemotherapy. Previous studies revealed that the long noncoding RNA DANCR positively regulated progression of prostate cancer. However, the precise roles of DANCR in the Taxol sensitivity of PCa and the underlying molecular mechanisms remain largely unknown. Here, we report that the expressions of DANCR were significantly upregulated and miR-33b-5p were downregulated in prostate tumor specimens and cells as well as the Taxol-resistant prostate cancer cell line (PC3-TXR). Silencing DANCR or overexpressing miR-33b-5p effectively enhanced the Taxol sensitivity of PCa cells. Bioinformatics analysis, RNA pull-down assay, and luciferase assay consistently illustrated that DANCR was associated with miR-33b-5p, leading to downregulation of miR-33b-5p in PCa. Interestingly, glucose metabolism of PC3-TXR cells was remarkedly elevated. The glucose uptake, extracellular acidification rate (ECAR), and glycolysis speed-limiting enzyme expressions were significantly promoted in PC3-TXR cells. We further identified the glucose metabolism enzyme; LDHA was a direct target of miR-33b-5p in PCa cells. LDHA restoration attenuated miR-33b-5p-mediated PTX sensitization. Finally, the rescue of miR-33b-5p in DANCR-overexpressing PC3-TXR cells successfully overrode the DANCR-promoted Taxol resistance. In summary, this study uncovered biological roles and molecular mechanisms of the DANCR-promoted chemoresistance, contributing to the development of noncoding RNA-based therapeutic strategies against drug-resistant prostate cancer.