Phosphoenolpyruvate Carboxykinase Activity Research Articles

The Supplementation of Berberine in High-Carbohydrate Diets Improves Glucose Metabolism of Tilapia (Oreochromis niloticus) via Transcriptome, Bile Acid Synthesis Gene Expression and Intestinal Flora.

Berberine is an alkaloid used to treat diabetes. This experiment aimed to investigate the effects of berberine supplementation in high-carbohydrate diets on the growth performance, glucose metabolism, bile acid synthesis, liver transcriptome, and intestinal flora of Nile tilapia. The six dietary groups were the C group with 29% carbohydrate, the H group with 44% carbohydrate, and the HB1-HB4 groups supplemented with 25, 50, 75, and 100 mg/kg of berberine in group H. The results of the 8-week trial showed that compared to group C, the abundance of Bacteroidetes was increased in group HB2 (p < 0.05). The cholesterol-7α-hydroxylase (CYP7A1) and sterol-27-hydroxylase (CYP27A1) activities were decreased and the expression of FXR was increased in group HB4 (p < 0.05). The pyruvate carboxylase (PC) and phosphoenolpyruvate carboxykinase (PEPCK) activities was decreased in group HB4 (p < 0.05). The liver transcriptome suggests that berberine affects carbohydrate metabolic pathways and primary bile acid synthesis pathways. In summary, berberine affects the glucose metabolism in tilapia by altering the intestinal flora structure, enriching differentially expressed genes (DEGs) in the bile acid pathway to stimulate bile acid production so that it promotes glycolysis and inhibits gluconeogenesis. Therefore, 100 mg/kg of berberine supplementation in high-carbohydrate diets is beneficial to tilapia.

Prenylated flavonoid fractions from Glycyrrhiza glabra alleviate insulin resistance in HepG2 cells by regulating the ERK/IRS-1 and PI3K/Akt signaling pathways.

Insulin resistance (IR) is a key factor in the pathogenesis of disrupted glucose metabolism. Although the extract of Glycyrrhiza glabra has shown significant hypoglycemic activity, its bioactive components remain to be identified, and their mechanisms of action, especially on hepatocyte glucose metabolism, are yet to be explored. In the present study, the primary compounds from Glycyrrhiza glabra [named prenylated flavonoid fractions (PFFs)] have been identified and their chemical structures have been elucidated. The therapeutic effects of PFFs extracted from G. glabra on glucose metabolism disorders and IR in high insulin-induced insulin-resistant HepG2 (IR-HepG2) cells have been determined. Glabridin (GLD) was used as a control. The results indicated that, similar to GLD, PFFs increased glucose consumption, glucose uptake, and translocation of glucose transporter 4 to the plasma membrane in IR-HepG2 cells. In addition, they enhanced the activities of glycogen synthase, glucokinase, and pyruvate kinase, while reducing the activities of phosphoenolpyruvate carboxykinase and glucose-6-phosphatase. Furthermore, they activated the phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) pathway and suppressed the extracellular signal-regulated kinase/insulin receptor substrate-1 (ERK/IRS-1) pathway. These findings suggest that, similar to GLD, PFFs can alleviate impaired glucose metabolism and alleviate IR in IR-HepG2 cells.Please check and confirm that the authors and their respective affiliations have been correctly identified and amend if necessary.The authors and their affiliations have been confirmed as correct.

High dietary wheat starch negatively regulated growth performance, glucose and lipid metabolisms, liver and intestinal health of juvenile largemouth bass, Micropterus salmoides.

Largemouth bass (Micropterus salmoides) were fed with three diets containing 6%, 12%, and 18% wheat starch for 70days to examine their impacts on growth performance, glucose and lipid metabolisms, and liver and intestinal health. The results suggested that the 18% starch group inhibited the growth, and improved the hepatic glycogen content compared with the 6% and 12% starch groups (P < 0.05). High starch significantly improved the activities of glycolysis-related enzymes, hexokinase (HK), glucokinase (GK), phosphofructokinase (PFK), and pyruvate kinase (PK) (P < 0.05); promoted the mRNA expression of glycolysis-related phosphofructokinase (pfk); decreased the activities of gluconeogenesis-related enzymes, pyruvate carboxylase (PC), and phosphoenolpyruvate carboxykinase (PEPCK); and reduced the mRNA expression of gluconeogenesis-related fructose-1,6-bisphosphatase-1(fbp1) (P < 0.05). High starch reduced the hepatic mRNA expressions of bile acid metabolism-related cholesterol hydroxylase (cyp7a1) and small heterodimer partner (shp) (P < 0.05), increased the activity of hepatic fatty acid synthase (FAS) (P < 0.05), and reduced the hepatic mRNA expressions of lipid metabolism-related peroxisome proliferator-activated receptor α (ppar-α) and carnitine palmitoyltransferase 1α (cpt-1α) (P < 0.05). High starch promoted inflammation; significantly reduced the mRNA expressions of anti-inflammatory cytokines transforming growth factor-β1 (tgf-β1), interleukin-10 (il-10), and interleukin-11β (il-11β); and increased the mRNA expressions of pro-inflammatory cytokine tumor necrosis factor-α (tnf-α), interleukin-1β (il-1β), and interleukin-8 (il-8) in the liver and intestinal tract (P < 0.05). Additionally, high starch negatively influenced the intestinal microbiota, with the reduced relative abundance of Trichotes and Actinobacteria and the increased relative abundance of Firmicutes and Proteobacteria. In conclusion, low dietary wheat starch level (6%) was more profitable to the growth and health of M. salmoides, while high dietary starch level (12% and 18%) could regulate the glucose and lipid metabolisms, impair the liver and intestinal health, and thus decrease the growth performance of M. salmoides.

Improving insulin resistance by sulforaphane via activating the Bacteroides and Lactobacillus SCFAs-GPR-GLP1 signal axis.

Background: Insulin resistance (IR) is closely associated with non-alcoholic fatty liver disease (NAFLD), and the gut microbiome contributes to the development of NAFLD. Sulforaphane (SFN) is a phytochemical in cruciferous vegetables that could improve lipid metabolism disorder. However, whether SFN can alleviate IR in NAFLD by regulating the intestinal flora remains unclear. Methods: SFN was administered to high fat diet (HFD)-fed Wistar rats for 10 weeks. Gut microbiota was analysed by 16S rRNA sequencing and the short chain fatty acids (SCFAs) by gas chromatography. The expression of tight junction protein and the numbers of Lactobacillus, Bacteroides and Bifidobacterium were determined by qPCR. The expression of G-protein-coupled receptor 41/43 (GPR41/43) was determined by western blot. A randomized controlled trial (RCT) was conducted in NAFLD patients with broccoli seed tablets (rich in SFN, 42 mg d-1) as intervention for 12 weeks. Thirty-six volunteers with abnormal glucose before the broccoli seed tablet treatment were selected in the intervention group to analyze their blood glucose, insulin, homeostasis model assessment-insulin resistance index (HOMA-IRI), homeostasis model assessment-insulin sensitivity index (HOMA-ISI) and glucagon-like peptide (GLP-1). Results: SFN reduced blood glucose and HOMA-IRI while increasing insulin sensitivity in HFD rats. SFN reduced glycogen synthase kinase 3 (GSK-3), phosphoenolpyruvate carboxykinase (PEPCK) activity, and phosphorylation of serine residues of IRS-2 induced by HFD. SFN reshaped the gut microbiota composition of HFD-induced rats and, especially, increased the content of Bacteroidaceae, Lactobacillaceae and Bifidobacteriaceae, which are related to the improvement from SFN of the blood glucose and HOMA-IRI. The increased numbers of Bacteroides and Lactobacillus were the targets of SFN to enhance the expression of tight junction proteins ZO-1 and occludin, thereby lowering lipopolysaccharide content to reduce inflammation, ultimately alleviating IR. Bacteroides and Lactobacillus produced SCFAs, which activated GPR41/43 to secrete GLP1. Moreover, it was also confirmed in RCT that SFN intervention increased the level of GLP1 in NAFLD patients, which was positively correlated with the reduction of blood glucose and HOMA-IR. Conclusions: SFN alleviated IR in NAFLD via the Bacteroides and Lactobacillus SCFAs-GPR41/43-GLP1 axis and protected the intestinal mucosal barrier to decrease inflammation.

Exogenous application of ALA enhanced sugar, acid and aroma qualities in tomato fruit.

The content and proportion of sugars and acids in tomato fruit directly affect its flavor quality. Previous studies have shown that 5-aminolevulinic acid (ALA) could promote fruit ripening and improve its aroma quality. In order to explore the effect of ALA on sugar and acid quality during tomato fruit development, 0, 100, and 200 mg L-1 ALA solutions were sprayed on the fruit surface 10 days after pollination of the fourth inflorescence, and the regulation of ALA on sugar, acid metabolism and flavor quality of tomato fruit was analyzed. The results showed that ALA treatment could enhance the activities of acid invertase (AI), neutral invertase (NI), and sucrose synthase (SS), reduce the activity of sucrose phosphate synthase (SPS), up-regulate the expression of SlAI, SlNI and SlSS, change the composition and content of sugar in tomato fruit at three stages, significantly increase the content of sugars in fruit, and promote the accumulation of sugars into flesh. Secondly, ALA treatments increased the activities of phosphoenolpyruvate carboxykinase (PEPC), malic enzyme (ME), and citrate synthase (CS), up-regulated the expression of SlPPC2, SlME1, and SlCS, and reduced the citric acid content at maturity stage, thereby reducing the total organic acid content. In addition, ALA could also increase the number and mass fraction of volatile components in mature tomato fruits. These results indicated that exogenous application of ALA during tomato fruit development could promote the formation of fruit aroma quality and were also conducive to the formation of fruit sugar and acid quality.

Effects of Vine Water Status on Malate Metabolism and γ-Aminobutyric Acid (GABA) Pathway-Related Amino Acids in Marselan (Vitis vinifera L.) Grape Berries.

Malic acid is the predominant organic acid in grape berries, and its content is affected by abiotic factors such as temperature (fruit zone microclimate) and water (vine water status). The objectives of this study were to explore the potential mechanisms behind the effects of vine water status on the biosynthesis and degradation of berry malic acid and the potential downstream effects on berry metabolism. This study was conducted over two growing seasons in 2021 and 2022, comprising three watering regimes: no water stress (CK), light water stress (LWS), and moderate water stress (MWS). Compared to CK, a significantly higher level of malic acid was found in berries from the MWS treatment when the berry was still hard and green (E-L 33) in both years. However, water stress reduced the malic acid content at the ripe berry harvest (E-L 38) stage. The activities of NAD-malate dehydrogenase (NAD-MDH) and pyruvate kinase (PK) were enhanced by water stress. Except for the E-L 33 stage, the activity of phosphoenolpyruvate carboxylase (PEPC) was reduced by water stress. The highest phosphoenolpyruvate carboxykinase (PEPCK) activity was observed at the berry veraison (E-L 35) stage and coincided with the onset of a decrease in the malate content. Meanwhile, the expression of VvPEPCK was consistent with its enzyme activity. This study showed that water stress changed the content of some free amino acids (GABA, proline, leucine, aspartate, and glutamate), two of which (glutamate and GABA) are primary metabolites of the GABA pathway.

Peculiarities of the relationship between the terminal site of glycolysis and the initial segment of gluconeogenesis in the myocardium and skeletal muscles of animals irradiated at different doses

Existing types of muscles differ not only structurally, but also metabolically (direction of energy exchange, choice of biosubstrates, dependence on the action of mediators, hormones, etc.). A number of studies have been devoted to the study of the impact of ionizing radiation on metabolism in muscle tissue. After irradiation, thickened muscle cells with enlarged nuclei appear in the heart muscle, the number of which does not decrease for 6 months, which indicates a violation of nuclear-cytoplasmic relations in myocardial cells. Phosphoenolpyruvate carboxykinase which ensures the utilization of cytoplasmic oxaloacetate and its transformation into phosphoenolpyruvate, completes the initial stage of gluconeogenesis and can limit the rate of gluconeogenesis from lactate. It should be emphasized that phosphoenolpyruvate carboxykinase is more active in skeletal muscles, where the activity of pyruvate kinase and lactate dehydrogenase is increased. The purpose of the work is to investigate the peculiarities of the relationship between the terminal site of glycolysis and the initial segment of gluconeogenesis in the myocardium and skeletal muscles of animals irradiated at different doses. The authors proved that in animals irradiated at a dose of 0.5 Gy, the activity of pyruvate kinase in the myocardium and skeletal muscle increases compared to intact animals. In the blood, on the contrary, there is a decrease in the activity of this enzyme compared to intact animals. When animals are irradiated at a dose of 1.0 Gy, diametrically opposite changes are observed. When animals are irradiated at a dose of 0.5 Gy, there is a slight decrease in the activity of lactate dehydrogenase in the myocardium and blood against the background of an increase in the activity of this enzyme in skeletal muscle. Irradiation of animals at a dose of 1.0 Gy leads to an acute increase in lactate dehydrogenase activity in the myocardium and skeletal muscle. The data obtained revealed that in animals irradiated at a dose of 0.5 Gy, the activity of phosphoenolpyruvate carboxykinase in skeletal muscle increases, while in cardiac muscle, on the contrary, its activity decreases as well as in blood. With an increase in the radiation dose to 1.0 Gy, diametrically opposite changes in the activity of phosphoenolpyruvate carboxykinase are observed. The authors concluded that outlined changes in the waу of intramuscular glycolysis and gluconeogenesis reactions show the pathophysiologcal mechanisms of biochemical supply restructuring as the result of ionizing irradiation influence. From the fundamental point of view these results show the direction of pathophysiologically oriented pharmacological correction of radiation-provoked muscle disturbances.

Dietary Effects of Lipid and Protein Levels on Growth, Feed Utilization, Lipid Metabolism, and Antioxidant Capacity of Triploid Rainbow Trout (Oncorhynchus mykiss).

This study investigated the dietary effects of lipid and protein levels on growth performance, feed utilization, body composition, lipid metabolism, and antioxidant capacity of triploid rainbow trout, Oncorhynchus mykiss. A 3 × 2 two-factor design was conducted with three crude lipid levels of 4%, 9%, and 14% (L4, L9, and L14) and two crude protein levels of 44%, 49% (P44, P49). Therefore, a total of six diets were prepared as P44/L4, P44/L9, P44/L14, P49/L4, P49/L9, and P49/L14. Triploid rainbow trout (initial body weight 65.0 ± 0.1 g) were fed one of the six diets for 80 days. The results showed that weight gain (WG), protein retention (PR), and protein efficiency rate (PER) significantly increased with increasing the dietary lipid level at the same crude protein level, while feed conversion ratio (FCR) and hepatosomatic index significantly decreased (P < 0.05). At the same lipid level, there was no difference in WG, FCR, PR, PER between 44% and 49% crude protein group (P > 0.05). The P49/L14 group had the highest WG (374.6%) and lowest FCR (1.25), while P44/L14 group had the highest PER (1.80) and PR (25.06%) with similar WG and FCR to P49/L14 group. The crude lipid contents in whole fish were significantly higher in the L14 group than those in the L4 and L9 groups (P < 0.05). Muscle n-3 PUFAs, n-6 PUFAs, and PUFAs levels were positively correlated with dietary lipid level, while n-6 PUFAs was negatively correlated with dietary protein level. Dietary protein, dietary lipid, and their interaction significantly affected hepatic malondialdehyde (MDA) content, aspartate aminotransferase, lipase (LPS), and fatty acid synthase (FAS) activities (P < 0.05). In both P44 and P49 groups, LPS and FAS activities increased with increasing the dietary lipid level. MDA content significantly decreased in the P44 group and increased in the P49 group with increasing the dietary lipid level (P < 0.05). As dietary protein level increased, serum total cholesterol level increased, while hepatic phosphoenolpyruvate carboxykinase activity decreased. With increasing the dietary lipid level, total superoxide dismutase, catalase, total nitric oxide synthase, and fructose-1,6-bisphosphatase activities showed an increasing trend, while the opposite was true for alanine aminotransferase activity. In conclusion, based on growth performance and feed utilization, dietary protein level of 44% and dietary lipid level of 14% (measured value, 43.71% and 13.62%) were suggested for young triploid rainbow trout.

Combined effects of dietary carbohydrate levels and ammonia stress on growth, antioxidant capacity and glucose metabolism in juvenile oriental river prawn (Macrobrachium nipponense).

Ammonia is a common environmental stress factor that constrains aquaculture industry development. This study evaluated the effect of carbohydrate levels and ammonia stress in oriental river prawn (Macrobrachium nipponense). The experiment had six treatments containing two water ammonia levels (0 and 5 mg/L) and three dietary carbohydrate levels (low carbohydrate diet (LCD, 10%), medium carbohydrate diet [MCD, 20%], and high carbohydrate diet [HCD, 30%]), and lasted six weeks. The results showed that the prawns fed on MCD had higher weight gain than those fed on LCD and HCD during ammonia stress. Moreover, the prawns fed on MCD had significantly lower acid phosphatase and alkaline phosphatase activities during ammonia stress. Feeding the prawns on the MCD increased B cells in the hepatopancreas during ammonia stress. Interestingly, the prawns fed on MCD had significantly lower superoxide dismutase activity compared to LCD and HCD during ammonia stress. Moreover, the prawns fed on MCD had significantly lower pyruvate kinase activity and pyruvate and lactic acid contents, while those fed on LCD had significantly higher succinic dehydrogenase, 6-phosphogluconic dehydrogenase, and phosphoenol pyruvate carboxykinase activities during ammonia stress. The prawns fed on the MCD increased significantly glutaminase activity and decreased the ammonia content in the serum during ammonia exposure. In addition, feeding the prawns on MCD decreased significantly the expression of apoptosis and inflammation-related genes. Taken together, the MCD supplied energy required to counteract ammonia stress, which increased growth, improved antioxidant capacity, facilitated ammonia excretion, and alleviated inflammation and apoptosis of the oriental river prawn.

Sir2 and Glycerol Underlie the Pro-Longevity Effect of Quercetin during Yeast Chronological Aging.

Quercetin (QUER) is a natural polyphenolic compound endowed with beneficial properties for human health, with anti-aging effects. However, although this flavonoid is commercially available as a nutraceutical, target molecules/pathways underlying its pro-longevity potential have yet to be fully clarified. Here, we investigated QUER activity in yeast chronological aging, the established model for simulating the aging of postmitotic quiescent mammalian cells. We found that QUER supplementation at the onset of chronological aging, namely at the diauxic shift, significantly increases chronological lifespan (CLS). Consistent with the antioxidant properties of QUER, this extension takes place in concert with a decrease in oxidative stress. In addition, QUER triggers substantial changes in carbon metabolism. Specifically, it promotes an enhancement of a pro-longevity anabolic metabolism toward gluconeogenesis due to improved catabolism of C2 by-products of yeast fermentation and glycerol. The former is attributable to the Sir2-dependent activity of phosphoenolpyruvate carboxykinase and the latter to the L-glycerol 3-phosphate pathway. Such a combined increased supply of gluconeogenesis leads to an increase in the reserve carbohydrate trehalose, ensuring CLS extension. Moreover, QUER supplementation to chronologically aging cells in water alone amplifies their long-lived phenotype. This is associated with intracellular glycerol catabolism and trehalose increase, further indicating a QUER-specific influence on carbon metabolism that results in CLS extension.

Implications on growth performance, glucose metabolism, PI3K/AKT pathway, intestinal flora induced by dietary taurine in a high-carbohydrate diet for grass carp (Ctenopharyngodon idella).

An 8-week experiment was performed to investigate the influence on growth performance, plasma biochemistry, glucose metabolism and the insulin pathway of supplementation of dietary taurine to a high-carbohydrate diet for grass carp. In this study, fish were fed diets at one of two carbohydrate levels, 31·49 % (positive control) or 38·61 % (T00). The high-carbohydrate basal diet (T00), without taurine, was supplemented with 0·05 % (T05), 0·10 % (T10), 0·15 % (T15) or 0·20 % (T20) taurine, resulting in six isonitrogenous (30·37 %) and isolipidic (2·37 %) experimental diets. The experimental results showed that optimal taurine level improved significantly weight gain, specific growth rate (SGR), feed utilisation, reduced plasma total cholesterol levels, TAG and promoted insulin-like growth factor level. Glucokinase, pyruvate kinase and phosphoenolpyruvate carboxykinase activities showed a quadratic function model with increasing dietary taurine level, while hexokinase, fatty acid synthetase activities exhibited a positive linear trend. Optimal taurine supplementation in high-carbohydrate diet upregulated insulin receptor (Ir), insulin receptor substrate (Irs1), phosphatidylinositol 3-kinase (pi3k), protein kinase B (akt1), glycogen synthase kinase 3 β (gs3kβ) mRNA level and downregulated insulin-like growth factor (igf-1), insulin-like growth factor 1 receptor (igf-1R) and Fork head transcription factor 1 (foxo1) mRNA level. The above results suggested that optimal taurine level could improve growth performance, hepatic capacity for glycolipid metabolism and insulin sensitivity, thus enhancing the utilisation of carbohydrates in grass carp. Based on SGR, dietary optimal tributyrin taurine supplementation in grass carp was estimated to be 0·08 %.

Dietary inositol improved glucose and lipid metabolism mediated by the Insulin-PI3K-Akt signaling pathway in Pacific white shrimp (Litopenaeus vannamei)

The present study aimed to evaluate the effects of dietary inositol level (0.86, 1.34, 1.40, 2.30, 3.88 and 7.50 g kg−1) on glucose and lipid homeostasis in Litopenaeus vannamei. The results indicated that the contents of inositol, phosphatidyl inositol (PI) and glycogen in hepatopancreas and muscle, very low-density lipoprotein (VLDL) in hepatopancreas and hemolymph, the activity of carnitine palmitoyl-transferase (CPT1) and the expression of hmit and inox were positively related to the dietary inositol levels, while the contents of glucose (GLU), crustacean hyperglycemic hormone (CHH), triglyceride (TG), cholesterol (CHO) and non-esterified fatty acid (NEFA) in hemolymph and the expression of imp, pepck, g6pc and fbp were negatively correlated with the dietary inositol level. TG content, phosphoenolpyruvate carboxykinase (PEPCK) activity and the expression levels of srebp, fas, acc1, g6pd and 6gpd in shrimp fed 3.88 and 7.50 g kg−1 inositol diets were significantly lower compared with shrimp fed the basal diet, while the expression of cpt1, aco, fabp, fatp and idir were showed the reverse change trend (P < 0.05). The activities of hexokinase (HK), phosphofructokinase (PFK), pyruvate kinase (PK) and the expression levels of ir, irs1, pi3k and akt were significantly increased as dietary inositol levels ranged from 1.40 to 7.50 g kg−1, while the expression levels of gsk-3β and foxo1 significantly down-regulated. Hepatopancreas R cells number in shrimp fed 2.30, 3.88 and 7.50 g kg−1 inositol diets were significantly increased compared with shrimp fed 0.86 g kg−1 inositol diet, while the diameters and areas showed an opposite trend. In addition, dietary inositol supplementation significantly increased hemolymph insulin like peptide (ILP) content but had no significant effect on high density lipoprotein cholesterol (HLDC) content in hemolymph, hepatic lipase (HL) activity and the ratio of n-3/ n-6 PUFA and DHA/EPA in hepatopancreas. In conclusion, appropriate dietary inositol could positively regulate the Insulin-PI3K-Akt pathway to promote glucose utilization and maintain the normal accumulation of glycogen and lipids required for development, while high dietary inositol could promote lipid mobilization and prevent hepatopancreas lipids deposition by negatively regulating the Insulin-PI3K-Akt pathway, improving ILP sensitivity and enhancing VLDL synthesis, which may therefore be an important mechanism in the action of inositol on glucose and lipid metabolism. These findings provided further insight and understanding of mechanisms by which dietary inositol regulated glucose and lipid metabolism in L. vannamei.

MLK4 promotes glucose metabolism in lung adenocarcinoma through CREB-mediated activation of phosphoenolpyruvate carboxykinase and is regulated by KLF5

MLK4, a member of the mitogen-activated protein kinase kinase kinase (MAP3K) family, has been implicated in cancer progression. However, its role in lung adenocarcinoma has not been characterized. Here, we showed that MLK4 was overexpressed in a significant subset of lung adenocarcinoma, associated with a worse prognosis, and exerted an oncogenic function in vitro and in vivo. Bioinformatics analyses of clinical datasets identified phosphoenolpyruvate carboxykinase 1 (PCK1) as a novel target of MLK4. We validated that MLK4 regulated PCK1 expression at transcriptional level, by phosphorylating the transcription factor CREB, which in turn mediated PCK1 expression. We further demonstrated that PCK1 is an oncogenic factor in lung adenocarcinoma. Given the importance of PCK1 in the regulation of cellular metabolism, we next deciphered the metabolic effects of MLK4. Metabolic and mass spectrometry analyses showed that MLK4 knockdown led to significant reduction of glycolysis and decreased levels of glycolytic pathway metabolites including phosphoenolpyruvate and lactate. Finally, the promoter analysis of MLK4 unravelled a binding site of transcription factor KLF5, which in turn, positively regulated MLK4 expression in lung adenocarcinoma. In summary, we have revealed a KLF5-MLK4-PCK1 signalling pathway involved in lung tumorigenesis and established an unusual link between MAP3K signalling and cancer metabolism.

Preparation and characteristics of pumpkin polysaccharides and their effects on abnormal glucose metabolism in diabetes mice

Oxidative stress is frequently implicated in the pathogenesis of various diseases, including diabetes mellitus resulting from uncontrolled glucose metabolism. Pumpkin polysaccharides have been shown to have a hypoglycemic effect, but their impact on abnormal glucose metabolism under oxidative stress is still unclear. We dried pumpkin flesh by far-infrared radiation, extracted and separated pumpkin polysaccharides from the dried flesh, and found that they were heteropolysaccharides primarily composed of galacturonic acid, glucose, galactose, and arabinose, with a molar ratio of 31.68:31.81:20.18:9.752. The number average (Mn) and weight average molecular weight (Mw) of pumpkin polysaccharides were 33.72 kDa and 70.88 kDa, respectively. The hemiacetal hydroxyl group forming the glycosidic bond in polysaccharides was mainly β-configuration. Additionally, we utilized streptozotocin (STZ) to induce oxidative stress and replicate an acute diabetic mouse model to study the effects of pumpkin polysaccharides on abnormal glucose metabolism. Our findings demonstrated pumpkin polysaccharides significantly reduced the levels of blood glucose, triglycerides (TG), and total cholesterol (TC) in diabetic mice (p < 0.05). Additionally, pumpkin polysaccharides significantly increased the activities of superoxide dismutase (SOD), catalase (CAT) and the level of the antioxidant glutathione (GSH) (p < 0.05), and decreased the content of the lipid peroxide malondialdehyde (MDA) in the liver (p < 0.05). Pumpkin polysaccharides also increased the activity of pyruvate kinase (PK) and decreased the activity of phosphoenolpyruvate carboxykinase (PEPCK) in the liver (p < 0.05). In conclusion, our study demonstrated pumpkin polysaccharides alleviate hyperglycemic symptoms in mice by mitigating oxidative stress damage and improving glucose metabolism disorders.

Influence of Dietary Phosphorus on the Growth, Feed Utilization, Proximate Composition, Intestinal Enzymes, and Oxidation Resistance of Sea Cucumber Apostichopus japonicus.

Six experimental diets (crude protein 12.58%, crude fat 1.93%, and total energy 10.72 kJ/kg) containing 0.24%, 0.37%, 0.51%, 0.62%, 0.77%, and 0.89% phosphorus were formulated to evaluate dietary phosphorus requirement for sea cucumber Apostichopus japonicus. The feeding trial was conducted in 18 fiberglass tanks (220 L) for 63 days. Each diet was randomly assigned to triplicate tanks of 50 sea cucumbers (9.99 g) and fed once daily. With the increase of dietary phosphorus level, weight gain (WG), specific growth rate (SGR), daily feed intake (DFI), feces production ratio, the activities of amylase, alkaline phosphatase, phosphofructokinase, succinate dehydrogenase, and glutathione peroxidase as well as the contents of glutathione and glutathione oxidized significantly increased and then decreased afterwards (P < 0.05). A. japonicus fed diet with 0.63%, 0.63%, and 0.55% dietary phosphorus was estimated to yield the highest WG (11.39 g), SGR (1.09%/d), and DFI (2.55%/d) according to the quadratic regression analysis of WG, SGR, and DFI against dietary phosphorus level, respectively. The apparent digestibility of dry material and energy followed an opposite tendency. Feed efficiency, the contents of whole-body phosphorus, initially increased and then plateaued, fitting piecewise-linear models with breakpoint at 0.57% and 0.55% dietary phosphorus. Daily phosphorus intake, pyruvate kinase activity, and the ratio of glutathione and glutathione oxidized increased (P < 0.05) but the apparent digestibility of phosphorus, the activities of alkaline protease, aspartate transaminase, and phosphoenolpyruvate carboxykinase decreased (P < 0.05), responding to the increasing dietary phosphorus. Considering the present results, the optimal dietary phosphorus for A. japonicus is 0.57-0.63%.

Dietary Methionine Restriction Alleviates Hyperglycemia in Pigs with Intrauterine Growth Restriction by Enhancing Hepatic Protein Kinase B Signaling and Glycogen Synthesis

BackgroundIndividuals with intrauterine growth restriction (IUGR) are prone to developing type 2 diabetes mellitus (T2DM). Dietary methionine restriction (MR) improves insulin sensitivity and glucose homeostasis in individuals with normal birth weight (NBW). ObjectiveThis study investigated the effects of MR on plasma glucose concentration and hepatic and muscle glucose metabolism in pigs with IUGR. MethodsThirty female NBW and 60 same-sex spontaneous IUGR piglets (Landrace × Yorkshire) were selected. After weaning (day 21), the piglets were fed diets with adequate methionine (NBW-CON and IUGR-CON) or 30% less methionine (IUGR-MR) (n = 6). At day 180, 1 pig with a body weight near the mean of each replication was selected for biochemical analysis. ResultsThe IUGR-CON group showed 41.6%, 68.6%, and 67.1% higher plasma glucose concentration, hepatic phosphoenolpyruvate carboxykinase activity, and glucose-6-phosphatase activity, respectively, than the NBW-CON group (P < 0.05). Muscle glycogen content and glycogen synthase activity were 36.9% and 38.8% lower, respectively, in the IUGR-CON than the NBW-CON group (P < 0.05), respectively, and there was decreased hepatic and muscle protein kinase B phosphorylation in the IUGR-CON group (P < 0.05). Compared with the IUGR-CON pigs, the IUGR-MR pigs had 28.7% lower plasma glucose concentrations (P < 0.05), which were similar to those of the NBW-CON pigs (P ≥ 0.05). The hepatic glycogen content and glycogen synthase activity of the IUGR-MR pigs were 62.9% and 50.8% higher than those of the IUGR-CON pigs (P < 0.05) and 53.5% and 84.3% higher than the NBW-CON pigs (P < 0.05), respectively. The IUGR-MR pigs’ hepatic and muscle protein kinase B phosphorylation was higher than that of the IUGR-CON pigs (P < 0.05) and similar to that of the NBW-CON pigs (P ≥ 0.05). ConclusionsMR attenuates hyperglycemia in IUGR pigs by enhancing hepatic protein kinase B signaling and glycogen synthesis, implying a potential nutritional strategy to prevent type 2 diabetes mellitus in IUGR offspring.

Two phosphoenolpyruvate carboxykinases with differing biochemical properties in Chlamydomonas reinhardtii.

Phosphoenolpyruvate carboxykinase (PEPCK) catalyses the reversible reaction of decarboxylation and phosphorylation of oxaloacetate (OAA) to generate phosphoenolpyruvate (PEP) and CO2 playing mainly a gluconeogenic role in green algae. We found two PEPCK isoforms in Chlamydomonas reinhardtii and we cloned, purified and characterised both enzymes. ChlrePEPCK1 is more active as decarboxylase than ChlrePEPCK2. ChlrePEPCK1 is hexameric and its activity is affected by citrate, phenylalanine and malate, while ChlrePEPCK2 is monomeric and it is regulated by citrate, phenylalanine and glutamine. We postulate that the two PEPCK isoforms found originate from alternative splicing of the gene or regulated proteolysis of the enzyme. The presence of these two isoforms would be part of a mechanism to finely regulate the biological activity of PEPCKs.

THE IMPACT OF HORMONE-VITAMIN COMPLEX ON FUNCTIONAL ACTIVITY OF THE MUSCLE TISSUE OF DESCENDANTS OF IRRADIATED ANIMALS.

The aim: To determine the hormone-vitamin complex impact on the terminal links of glycolysis, the tricarboxylic acids cycle, and the initial stage of glucone¬ogenesis in the muscle tissue in descendants of irradiated animals. Materials and methods: Pyruvate kinase, lactate dehydrogenase, malate dehydrogenase, NADP-dependent malate dehydrogenasee and phosphoenolpyruvate carboxykinase activities, the content of lactate, pyruvate, malate and oxaloacetate were determined in the blood, myocardium and thigh muscles of 66 rats after exposure to ionizing gamma-radiation. Rats were injected by a hormone-vitamin complex which efficacy was determined using the abovementioned indexes. Results: Hormone-vitamin complex administration to descendants of irradiated animals exposed to 1.0 Gy results to pyruvate kinase activity increase in the myocardium and skeletal muscles of descendants from animals irradiated by 0.5 Gy and exposed to 1.0 Gy irradiation. Blood serum pyruvate kinase activity in descendants from animals irradiated by 1.0 Gy and exposed to 1.0 Gy radiation after the pharmacological correction was higher compared with the same index before pharmacological correction. The lactate dehydrogenase activity in the myocardium, skeletal muscles and blood in descendants born from animals irradiated by maximal dose exposed to 1.0 Gy radiation was less in these tissues after pharmacological correction. Conclusions: The hormone-vitamin complex use in the descendants of irradiated animals led to muscle tissue energy resources improvement. Our data are the experimental background for theoriginal hormone-vitamin complex efficacy further evaluation in the aspect of vital organs and body systems functional activity restoration under the influence of ionizing radiation.

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.

Dietary thiamine modulates carbohydrate metabolism, antioxidant status, and alleviates hypoxia stress in oriental river prawn Macrobrachium nipponense (de Haan)

Hypoxia is one of the challenges in prawns aquaculture. However, the role of thiamine, which is a coenzyme in carbohydrate metabolism with antioxidant properties, in reducing hypoxia in prawns aquaculture is currently unknown. We investigated the effects of thiamine on antioxidant status, carbohydrate metabolism and acute hypoxia in oriental river prawn, Macrobrachium nipponense. One thousand eight hundred prawns (0.123 ± 0.003 g) were fed five diets (60 prawns each tank, six replicates per diet) supplemented with graded thiamine levels (5.69, 70.70, 133.67, 268.33 and 532.00 mg/kg dry mater) for eight weeks and then exposed to hypoxia stress for 12 h followed by reoxyegnation for 12 h. The results showed that, under normoxia, prawns fed the 133.67 or 268.33 mg/kg thiamine diet had significantly lower glucose 6-phosphatedehydrogenase, succinate dehydrogenase and phosphoenolpyruvate carboxykinase activities than those fed the other diets. Moreover, total antioxidant capacity (T-AOC) increased significantly when prawns were fed the 133.67 mg/kg thiamine diet. Superoxide dismutase (SOD) activity and malonaldehyde (MDA) content also increased significantly when prawns were fed the 268.33 or 532.00 mg/kg thiamine diet under hypoxia. And the significantly increased SOD activity and MDA level also observed in prawns fed 532.00 mg/kg thiamine under reoxygenation. Under normoxia, prawns fed the 70.70 or 133.67 mg/kg thiamine diet decreased the mRNA expressions of AMP-activated protein kinase-alpha (AMPK-α), pyruvate dehydrogenase-E1-α subunit (PDH-E1-α) and hypoxia-inducible factor-1s (HIF-1α, HIF-1β), but increased the mRNA expressions of phosphofructokinase (PFK) significantly. After 12 h of hypoxia, the energy metabolism related genes (AMPK-β, AMPK-γ, PFK, PDH-E1-α), hypoxia-inducible factor related genes (HIF-1α, HIF-1β) and thiamine transporter gene (SLC19A2) were up-regulated significantly in prawns fed the 133.67 or 268.33 mg/kg thiamine diets. After 12 h of reoxygenation, prawns fed the 133.67 or 268.33 mg/kg diet significantly decreased the SOD activity, MDA level and SLC19A2 mRNA expression compared with other diets. The optimum thiamine was 161.20 mg/kg for minimum MDA content and 143.17 mg/kg for maximum T-AOC activity based on cubic regression analysis. In summary, supplementing 143.17 to 161.20 mg/kg thiamine in the diets for M. nipponense improves the antioxidant capacity under normoxia and reduces the oxidative damage under hypoxia stress.