Intermediates Of Glucose Metabolism Research Articles

Ferroptosis-related gene glutathione peroxidase 4 promotes reprogramming of glucose metabolism via Akt-mTOR axis in intrahepatic cholangiocarcinoma.

The role of the ferroptosis-related gene glutathione peroxidase 4 (GPX4) in oncology has been extensively investigated. However, the clinical implications of GPX4 in patients with intrahepatic cholangiocarcinoma (ICC) remain unknown. This study aimed to evaluate the prognostic impact of GPX4 and its underlying molecular mechanisms in patients with ICC. Fifty-seven patients who underwent surgical resection for ICC between 2010 and 2017 were retrospectively analyzed. Based on the immunohistochemistry, patients were divided into GPX4 high (n = 15) and low (n = 42) groups, and clinical outcomes were assessed. Furthermore, the roles of GPX4 in cell proliferation, migration and gene expression were analyzed in ICC cell lines in vitro and in vivo. The results from clinical study showed that GPX4 high group showed significant associations with high SUVmax on 18F-fluorodeoxyglucose-positron emission tomography (≥8.0, P = 0.017), multiple tumors (P = 0.004), and showed glucose transporter 1 (GLUT1) high expression with a trend toward significance (P = 0.053). Overall and recurrence-free survival in the GPX4 high expression group were significantly worse than those in the GPX4 low expression group (P = 0.038 and P < 0.001, respectively). In the experimental study, inhibition of GPX4 attenuated cell proliferation and migration in ICC cell lines. Inhibition of GPX4 also decreased the expression of glucose metabolism-related genes, such as GLUT1 or HIF1α. Mechanistically, these molecular changes are regulated in Akt-mechanistic targets of rapamycin axis. In conclusion, this study suggested the pivotal value of GPX4 serving as a prognostic marker for patients with ICC. Furthermore, GPX4 can mediate glucose metabolism of ICC.

Glucose controls manganese homeostasis through transcription factors regulating known and newly identified manganese transporter genes in Bacillus subtilis

Mn2+ is an essential nutrient whose concentration is tightly controlled in bacteria. In B. subtilis, the Mn2+-activated transcription factor MntR controls Mn2+ transporter genes. However, factors regulating intracellular Mn2+ concentration are incompletely understood. Here, we found that glucose addition induces an increase in intracellular Mn2+ concentration. We determined this upshift was mediated by glucose induction (GI) of the major Mn2+ importer gene mntH by the transcription factor AhrC, which is known to be involved in arginine metabolism and to be indirectly induced by glucose. In addition, we identified novel AhrC-regulated genes encoding the Mn2+ importer YcsG and the ABC-type exporter YknUV. We found the expression of these genes was also regulated by glucose and contributes to the GI of Mn2+ concentrations. ycsG expression is regulated by MntR as well. Furthermore, we analyzed the interaction of AhrC and MntR with the promoter driving ycsG expression and examined the Mn2+-dependent induction of this promoter to identify the transcription factors responsible for the Mn2+ induction. RNA-Seq revealed that disruption of ahrC and mntR affected the expression of 502 and 478 genes, respectively (FDR, <0.001, log2[FC], 2). The AhrC- and/or MntR-dependent expression of twenty promoters was confirmed by LacZ analysis, and AhrC or MntR binding to some of these promoters was observed via electromobility shift assay. The finding that glucose promotes an increase in intracellular Mn2+ levels without changes in extracellular Mn2+ concentrations is reasonable for the bacterium, as intracellular Mn2+ is required for enzymes and pathways mediating glucose metabolism.

Effect of heterologous platelet-rich plasma on liver and modulation of glucose metabolism and Wnt signalling pathways in diabetic mice.

The current study was designed to highlight the effects of heterologous platelet-rich plasma (PRP) on deteriorated hepatic tissues and impaired glucose metabolism of alloxan-induced diabetic mice. 30 male mice were divided into a control (CG), PRP (PG), diabetic (DG), and two treated groups (T1G and T2G). PG was given PRP treatment (0.5 ml/kg body weight) twice a week for four weeks. DG, T1G and T2G were given alloxan (150mg/kg) to induce diabetes. After confirmation, PRP treatment was given to T1G and T2G for two and four weeks respectively while DG was left untreated. Upon completion of the said experimental period, liver samples were taken for histological and gene expression analyses. The study found that the liver tissue of the DG group showed signs of damage, including hepatocyte ballooning, sinusoid dilatation, and collagen deposition. However, these changes were significantly reduced in both T1G and T2G groups. The expression of several genes related to liver function was also affected, with upregulation of Fbp1 and Pklr, and downregulation of Pck1 in the DG group. PRP treatment restored Fbp1 expression and also increased the expression of glycolytic pathway genes Hk1 and Gck, as well as Wnt signalling pathway genes Wnt2, Wnt4, and Wnt9a in both treated groups. Current study revealed that heterologous PRP may partly alleviate high glucose levels in diabetics possibly by mediating glucose metabolism via inhibition of Wnt signalling pathway.

Epidermal Growth Factor Receptor in Hepatic Endothelial Cells Suppresses MCP-1-Dependent Monocyte Recruitment in Diabetes.

Insulin resistance is a compromised response to insulin in target tissues such as liver. Emerging evidence shows that vascular endothelial cells (ECs) are critical in mediating glucose metabolism. However, how liver ECs can regulate inflammation in the setting of insulin resistance is still unknown. Using genome-wide transcriptome analysis of ECs isolated from diabetic mice, we found enrichment of the genes involved in epidermal growth factor receptor (Egfr) signaling. In line with this, hepatic sinusoidal ECs in diabetic mice had elevated levels of Egfr expression. Interestingly, we found an increased number of hepatic myeloid cells, especially macrophages, and systemic glucose intolerance in Cdh5Cre/+Egfrfl/fl mice lacking Egfr in ECs compared with littermate control mice with type II diabetes. Egfr deficiency upregulated the expression of MCP-1 in hepatic sinusoidal ECs. This resulted in augmented monocyte recruitment and macrophage differentiation in Cdh5Cre/+Egfrfl/fl mice compared with littermate control mice as determined by a mouse model of parabiosis. Finally, MCP-1 neutralization and hepatic macrophage depletion in Cdh5Cre/+Egfrfl/fl mice resulted in a reduced number of hepatic macrophages and ameliorated glucose intolerance compared with the control groups. Collectively, these results demonstrate a protective endothelial Egfr signaling in reducing monocyte-mediated hepatic inflammation and glucose intolerance in type II diabetic mice.

From cause to consequence: Insights into incident diabetes mellitus after hepatic steatosis

From cause to consequence: Insights into incident diabetes mellitus after hepatic steatosis

Genistein protects against hyperglycemia and fatty liver disease in diet-induced prediabetes mice via activating hepatic insulin signaling pathway.

Insulin signaling via the insulin receptor (IR) may be associated with the amelioration of diet-induced metabolic syndrome. Genistein, a soy isoflavone, has been suggested to play a role in the amelioration of high-fat diet-induced metabolic disorders. Here, we aimed to explore whether genistein regulates glucose and hepatic lipid by activating the insulin signaling pathway in diet-induced obesity mice. We showed that treatment of western-style diet-fed mice with genistein (60 mg/kg) significantly improved insulin resistance with decreased hyperglycemia and HOMA-IR index. These effects were linked to activating hepatic IRβ/PI3K/Akt signaling. Furthermore, genistein suppressed gluconeogenesis and promoted glycogen synthesis to maintain glucose homeostasis by increasing the phosphorylation of hepatic FOXO1/GSK3β in vivo and in vitro. The reduced level of insulin and upregulation of insulin signaling in genistein-treated mice also lead to an increase in hepatic energy status by inducing energy-sensing AMPK, reducing hepatic SREBP1c/ACC/FAS without affecting β-oxidation to prevent hepatic lipid accumulation. The protective effect of genistein on hepatic lipid accumulation was also validated in vitro. Besides, genistein had little effect on improvements in intestinal function and liver inflammation. Taken together, our results showed that genistein prevents insulin resistance and hyperglycemia through improvements in hepatic function. This study provides new insight into the mechanisms of genistein mediating glucose metabolism and suggests that genistein may be a promising diet ingredient for preventing prediabetes and hepatic lipid accumulation.

Association of Serum Leptin with Gestational Diabetes Mellitus

Background: It has been stated that leptin has a role in glucose regulation as it decreases the insulin resistance and regulates the insulin mediated glucose metabolism. As the body need more glucose, more secretion of insulin which stimulates adipose tissues to secrete more leptin which causes the release of cytokines which decreases insulin sensitivity and develop insulin resistance. The aim of the current study was to find out the association of serum leptin with gestational diabetes mellitus in current setting. Methods: A case control study was conducted at the Gynecology department of Abbasi Shaheed Hospital Karachi during April to September 2022. A self-designed proforma was used, consisting of 4 parts consisting of demographic variables, general physical examination and laboratory findings. Blood sample was collected during 24th to 28th week of gestation for testing fasting blood sugar, OGTT and then ELISA was done. Statistical Package for Social Science (SPSS) version-20 was used to analyze the data. p-value ≤0.05 was considered as significant. Results: The mean age of the study participants was 27.42 ± 0.39 and 24.96 ± 0.51 in cases and controls respectively. The basal metabolic index (BMI) was higher among the cases of gestational diabetes as compared to normal controls. Likewise, oral glucose tolerance test results showed higher levels of blood glucose than the normal controls during all steps of the test. The comparison of serum insulin and serum leptin during pregnancy and after delivery in cases of gestational diabetes showed a decrease in both serum insulin and serum leptin levels with significant p-value (p-value ≤0.05). Conclusion: Leptin is the contributory factor of insulin resistance and leads to gestational diabetes mellitus. Both serum insulin and serum leptin levels were having strong significant association with gestational diabetes mellitus. Keywords: Gestational diabetes mellitus, Serum Leptin, Hyperinsulinemia

Effect of yoga intervention on skeletal muscle linked glucose homeostasis in pre-diabetic individuals: Study protocol for a randomized controlled trial

BackgroundThe pre-diabetic stage is important in terms of identification and timely management due to its reversible nature. Along with other factors, insulin resistance in skeletal muscle is often considered as primary defect before development of overt hyperglycemia and Diabetes Mellitus (DM). Physical exercises are beneficial in prevention of DM by improving skeletal muscle mediated glucose metabolism. Evidence suggests that Yoga interventions appear to be equal and/or superior to exercise in most outcome measures. As the Yogic postures are relatable to exercises, they are considered to improve skeletal muscle function and reverse the pre-diabetic stage. MethodsThis open-labelled, randomized clinical study is planned to evaluate effect of Yoga interventions on muscle mass, strength, endurance and flexibility which are direct/indirect indicators of fat deposition in skeletal muscles. Association between changes in muscle quality/ functionality and glycemic control will also be explored. With ethics committee permission, 120 pre-diabetic individuals of either sex between age group of 35–49 years with BMI range of 25–35 kg/m2 and family history of Type 2 Diabetes Mellitus (T2DM) will be recruited after obtaining written informed consent. They will be randomly allocated to either Yoga or exercise group by computer generated randomized method in a 1:1 ratio. One group will receive defined Yoga interventions, while other group will receive fixed program of physical exercises. Prior to initiating this 12-week study, both groups will undergo a training session for 4 weeks under supervision of a trained instructor. The outcome measures will be parameters related to muscle quality/functionality and glucose metabolism markers. DiscussionOur study aims to explore practicality of Yoga in pre-diabetic stage on skeletal muscle related glycemic control, which is novel. Additionally, the study will generate awareness about pre-diabetes and provide people with active coping skills for reversing it.

Abstract 13180: Trans-Valvular Unloading Reduces Anaerobic Glycolysis Before Reperfusion and Preserves Energy Substrate Utilization After Reperfusion in Models of Acute Myocardial Infarction

Background: The impact of mechanical left ventricular (LV) unloading before reperfusion on myocardial energetics in acute myocardial infarction (AMI) is unknown. We hypothesized that LV unloading reduces anaerobic glycolysis in models of ischemia reperfusion injury (IRI). Methods: Myocardial ischemia was induced by percutaneous occlusion of the left anterior descending (LAD) artery for 90 minutes in adult swine. In Groups A and B, an additional 120 minutes of LAD occlusion without reperfusion was performed in the presence or absence of a trans-valvular pump (TVP). In Group C and D, an additional 120 minutes of reperfusion was performed in the presence or absence TVP (Fig. 1A). Untargeted Metabolomics was performed on the tissues from the infarct zones. Results: Compared to Group A, infarct size normalized to the area at risk (IS/AAR) was significantly smaller with LV unloading after ischemia alone (Group B; Fig 1B) and reperfusion (Group D; Fig 1B). Principal component analysis analysis of 800 metabolites identified 5 distinct clusters corresponding to the 4 study groups and sham controls (Fig 1C). LV unloading without reperfusion reduced lactate by 30±4% (p&lt;0.006), glucose by 25±5% (p&lt;0.02), and intermediates of glucose metabolism, Fructose 1,6-diphosphate by 9.3%, p&lt;0.008) and ATP by 14±5% (p&lt;0.04) consistent with decreased anaerobic glycolysis and reduced myocardial oxygen demand (Fig 1D Groups A and B). LV unloading followed by reperfusion increased lactate and glucose levels by 30±5% and 75±30% (p&lt;0.05). Consistent with reduced glycolytic metabolites during ischemia with unloading, we observed significantly reduced levels of genes and proteins associated with glycolysis including mRNA expression of Glut1 and PDK1 within the infarct zone.We report for the first time that LV unloading during coronary occlusion reduces anaerobic glycolysis, energy substrate utilization and ATP production before reperfusion.

Roles of Hydrogen Gas in Plants under Abiotic Stress: Current Knowledge and Perspectives.

Hydrogen gas (H2) is a unique molecular messenger, which is known to be involved in diverse physiological processes in plants, from seed germination to seedling growth to regulation of environmental stresses. In this review, we focus on the role of H2 in plant responses to abiotic stresses, such as temperature, osmotic stress, light, paraquat (PQ)-induced oxidative stresses, and metal stresses. In general, H2 can alleviate environmental stresses by improving the antioxidant defense system, photosynthetic capacity, re-establishing ion homeostasis and glutathione homeostasis, maintaining nutrient element homeostasis, mediating glucose metabolism and flavonoid pathways, regulating heme oxygenase-1 (HO-1) signaling, and interaction between H2 and nitric oxide (NO), carbonic oxide (CO), or plant hormones. In addition, some genes modulated by H2 under abiotic stresses are also discussed. Detailed evidence of molecular mechanisms for H2-mediated particular pathways under abiotic stress, however, is scarce. Further studies regarding the regulatory roles of H2 in modulating abiotic stresses research should focus on the molecular details of the particular pathways that are activated in plants. More research work will improve knowledge concerning possible applications of hydrogen-rich water (HRW) to respond to abiotic stresses with the aim of enhancing crop quality and economic value.

IFT20 governs mesenchymal stem cell fate through positively regulating TGF-β-Smad2/3-Glut1 signaling mediated glucose metabolism

Aberrant lineage allocation of mesenchymal stem cells (MSCs) could cause bone marrow osteoblast-adipocyte imbalance, and glucose as an important nutrient is required for the maintenance of the MSCs' fate and function. Intraflagellar transport 20 (IFT20) is one of the IFT complex B protein which regulates osteoblast differentiation, and bone formation, but how IFT20 regulates MSCs’ fate remains undefined. Here, we demonstrated that IFT20 controls MSC lineage allocation through regulating glucose metabolism during skeletal development. IFT20 deficiency in the early stage of MSCs caused significantly shortened limbs, decreased bone mass and significant increase in marrow fat. However, deletion of IFT20 in the later stage of MSCs and osteocytes just slightly decreased bone mass and bone growth and increased marrow fat. Additionally, we found that loss of IFT20 in MSCs promotes adipocyte formation, which enhances RANKL expression and bone resorption. Conversely, ablation of IFT20 in adipocytes reversed these phenotypes. Mechanistically, loss of IFT20 in MSCs significantly decreased glucose tolerance and suppressed glucose uptake and lactate and ATP production. Moreover, loss of IFT20 significantly decreased the activity of TGF-β-Smad2/3 signaling and reduced the binding activity of Smad2/3 to Glut1 promoter to downregulate Glut1 expression. These findings indicate that IFT20 plays essential roles for preventing MSC lineage allocation into adipocytes through TGF-β-Smad2/3-Glut1 axis.

Ecdysoneless Overexpression Drives Mammary Tumorigenesis through Upregulation of C-MYC and Glucose Metabolism.

We demonstrate ECD overexpression in the mammary gland of mice led to the development of a tumor progression model through upregulation of c-MYC signaling and glucose metabolism.

Effect of SLC16A1 on Hepatic Glucose Metabolism in Newborn and Post-Weaned Holstein Bulls.

Background: Patterns of liver energy metabolism significantly differ from birth to adult in cattle undergoing change of rumen rumination. However, the genes involve in hepatic energy metabolism during bovine development and how regulate are still unclear. Methods: In this study, 0-day-old newborn calves (0W) and 9-week-old weaned calves (9W) were used to investigate differences in liver glucose metabolism at these stages of calf development. We did this primarily through the quantitation of energy metabolism indicators, then sequencing the liver transcriptome for each group of claves. Results: The transcriptome results showed 979 differentially expressed genes (DEGs), enriched in animal organ development, catabolic process, transmembrane transport. SLC16A1 involved in that and was locked to investigate. We explored the effects of SLC16A1 on glucose and lactate flux in vitro. We identified and verified its target, miR-22-3p, through bioinformatics and luciferase reporter assays. Moreover, this study found that miR-22-3p decreased cell activity by negatively regulating the SLC16A1. Importantly, our result showed the insulin-induced SLC16A1 mRNA expression decreased, regulated by promoter activity rather than miR-22-3p. Conclusions: Our study illustrates the role of SLC16A1 in the liver mediated metabolism of developing calves. These data enrich our knowledge of the regulatory mechanisms of liver mediated glucose metabolism in developing cattle.

Trans-Valvular Unloading Reduces Anaerobic Glycolysis Before Reperfusion and Preserves Energy Substrate Utilization After Reperfusion in Models of Acute Myocardial Infarction

<h3>Purpose</h3> The impact of mechanical left ventricular (LV) unloading before reperfusion on myocardial energetics in acute myocardial infarction (AMI) is unknown. We hypothesized that LV unloading reduces anaerobic glycolysis in models of ischemia reperfusion injury (IRI). <h3>Methods</h3> Myocardial ischemia was induced by percutaneous occlusion of the left anterior descending (LAD) artery for 90 minutes in adult swine. In Groups A and B, an additional 120 minutes of LAD occlusion was performed in the presence or absence of a trans-valvular pump (TVP). In Group C and D, post ischemia or LV unloading was followed by 120 minutes of reperfusion (Fig. 1A). Tissue from the infarct and non-infarct zones was analyzed using Ultrahigh Performance Liquid Chromatography-Tandem Mass Spectroscopy. <h3>Results</h3> In Groups A/B, LV unloading without reperfusion reduced lactate by 30±4% (p<0.006), glucose by 25±5% (p<0.02), and intermediates of glucose metabolism and ATP production consistent with decreased anaerobic glycolysis and reduced myocardial oxygen demand (Fig. 1B-C). In Groups C/D, LV unloading before reperfusion increased lactate and glucose levels by 30±5% and 75±30%, respectively (p<0.05), and increased intermediates of glucose oxidation and the tricarboxylic acid cycle. <h3>Conclusion</h3> We report for the first time that LV unloading during coronary occlusion reduces anaerobic glycolysis, energy substrate utilization and ATP production. These data support the need for further studies exploring the utility of LV unloading in AMI.

Glucose- and Non-Glucose-Induced Mitochondrial Dysfunction in Diabetic Kidney Disease.

Mitochondrial dysfunction plays an important role in the pathogenesis and progression of diabetic kidney disease (DKD). In this review, we will discuss mitochondrial dysfunction observed in preclinical models of DKD as well as in clinical DKD with a focus on oxidative phosphorylation (OXPHOS), mitochondrial reactive oxygen species (mtROS), biogenesis, fission and fusion, mitophagy and urinary mitochondrial biomarkers. Both glucose- and non-glucose-induced mitochondrial dysfunction will be discussed. In terms of glucose-induced mitochondrial dysfunction, the energetic shift from OXPHOS to aerobic glycolysis, called the Warburg effect, occurs and the resulting toxic intermediates of glucose metabolism contribute to DKD-induced injury. In terms of non-glucose-induced mitochondrial dysfunction, we will review the roles of lipotoxicity, hypoxia and vasoactive pathways, including endothelin-1 (Edn1)/Edn1 receptor type A signaling pathways. Although the relative contribution of each of these pathways to DKD remains unclear, the goal of this review is to highlight the complexity of mitochondrial dysfunction in DKD and to discuss how markers of mitochondrial dysfunction could help us stratify patients at risk for DKD.

De novo serine synthesis regulates chondrocyte proliferation during bone development and repair

The majority of the mammalian skeleton is formed through endochondral ossification starting from a cartilaginous template. Cartilage cells, or chondrocytes, survive, proliferate and synthesize extracellular matrix in an avascular environment, but the metabolic requirements for these anabolic processes are not fully understood. Here, using metabolomics analysis and genetic in vivo models, we show that maintaining intracellular serine homeostasis is essential for chondrocyte function. De novo serine synthesis through phosphoglycerate dehydrogenase (PHGDH)-mediated glucose metabolism generates nucleotides that are necessary for chondrocyte proliferation and long bone growth. On the other hand, dietary serine is less crucial during endochondral bone formation, as serine-starved chondrocytes compensate by inducing PHGDH-mediated serine synthesis. Mechanistically, this metabolic flexibility requires ATF4, a transcriptional regulator of amino acid metabolism and stress responses. We demonstrate that both serine deprivation and PHGDH inactivation enhance ATF4 signaling to stimulate de novo serine synthesis and serine uptake, respectively, and thereby prevent intracellular serine depletion and chondrocyte dysfunction. A similar metabolic adaptability between serine uptake and de novo synthesis is observed in the cartilage callus during fracture repair. Together, the results of this study reveal a critical role for PHGDH-dependent serine synthesis in maintaining intracellular serine levels under physiological and serine-limited conditions, as adequate serine levels are necessary to support chondrocyte proliferation during endochondral ossification.

Placental Endocrine Activity: Adaptation and Disruption of Maternal Glucose Metabolism in Pregnancy and the Influence of Fetal Sex.

The placenta is an endocrine fetal organ, which secretes a plethora of steroid- and proteo-hormones, metabolic proteins, growth factors, and cytokines in order to adapt maternal physiology to pregnancy. Central to the growth of the fetus is the supply with nutrients, foremost with glucose. Therefore, during pregnancy, maternal insulin resistance arises, which elevates maternal blood glucose levels, and consequently ensures an adequate glucose supply for the developing fetus. At the same time, maternal β-cell mass and function increase to compensate for the higher insulin demand. These adaptations are also regulated by the endocrine function of the placenta. Excessive insulin resistance or the inability to increase insulin production accordingly disrupts physiological modulation of pregnancy mediated glucose metabolism and may cause maternal gestational diabetes (GDM). A growing body of evidence suggests that this adaptation of maternal glucose metabolism differs between pregnancies carrying a girl vs. pregnancies carrying a boy. Moreover, the risk of developing GDM differs depending on the sex of the fetus. Sex differences in placenta derived hormones and bioactive proteins, which adapt and modulate maternal glucose metabolism, are likely to contribute to this sexual dimorphism. This review provides an overview on the adaptation and maladaptation of maternal glucose metabolism by placenta-derived factors, and highlights sex differences in this regulatory network.

Comparing the effects of palmitate, insulin, and palmitate‐insulin co‐treatment on myotube metabolism and insulin resistance

Previous studies have shown various metabolic stressors such as saturated fatty acids (SFA) and excess insulin promote insulin resistance in metabolically meaningful cell types (such as skeletal muscle). Additionally, these stressors have been linked with suppressed mitochondrial metabolism, which is also a common characteristic of skeletal muscle of diabetics. This study characterized the individual and combined effects of excess lipid and excess insulin on myotube metabolism and related metabolic gene and protein expression. C2C12 myotubes were treated with either 500 μM palmitate (PAM), 100 nM insulin (IR), or both (PAM-IR). qRT-PCR and western blot were used to measure metabolic gene and protein expression, respectively. Oxygen consumption was used to measure mitochondrial metabolism. Glycolytic metabolism and insulin-mediated glucose uptake were measured via extracellular acidification rate. Cellular lipid and mitochondrial content were measured using Nile Red and NAO staining, respectively. IR and PAM-IR treatments led to reductions in p-Akt expression. IR treatment reduced insulin mediated glucose metabolism while PAM and PAM-IR treatment showed increases with concurrent reductions in mitochondrial metabolism. All three treatments showed suppression in mitochondrial metabolism. PAM and PAM-IR also showed increases in glycolytic metabolism. While PAM and PAM-IR significantly increased lipid content, expression of inflammatory and lipogenic proteins were unaltered. Lastly, PAM-IR reduced BCAT2 protein expression, a regulator of BCAA metabolism. Both stressors independently reduced insulin signaling, mitochondrial function, and cell metabolism, however, only PAM-IR co-treatment significantly reduced the expression of regulators of metabolism not seen with individual stressors, suggesting an additive effect of stressors on metabolic programming.

FoxO1 in Micropterus salmoides: Molecular characterization and its roles in glucose metabolism by glucose or insulin-glucose loading

Forkhead box O1 (FoxO1), a nuclear transcription factor, plays an important role in insulin-mediated glucose metabolism. In this study, FoxO1 gene from largemouth bass (Micropterus salmoides) was cloned and characterized, and its effects on hepatic glucose metabolism regulated by insulin-AKT pathway were investigated in response to glucose or insulin-glucose injection. The full-length cDNA of FoxO1 consisted of 2541 bp and encoded 680 amino acids. Sequence alignments and phylogenetic analysis revealed that FoxO1 exhibited a high degree of conservation among teleost, retaining one forkhead domain, one transactivation domain, and three phosphorylation sites. FoxO1 mRNA was expressed in a wide range of tissues, and high in the brain and liver. Glucose loading resulted in persistent hyperglycemia, and plasma insulin levels remained unchanged except at 1 h. After the insulin-glucose injection, insulin levels were significantly elevated and glucose levels recovered to the basal value after 6 h, which indicated insufficient insulin secretion caused persistent hyperglycemia in this species. Compared with the glucose injection group, transcript levels and enzyme activities of hepatic glycolysis-related genes (GK and PK) were significantly activated, and gluconeogenesis-related genes (PEPCK and G6Pase) were significantly depressed at 3 h after the insulin-glucose injection. Besides, phosphorylation of AKT-FoxO1 pathway was significantly activated. Therefore, insulin improved glucose metabolism by activating the AKT-FoxO1 phosphorylation to decrease hyperglycemia stress after the meal, which indicated insufficient insulin secretion was the reason for glucose intolerance in largemouth bass. Meanwhile, conserved S267 and S329 phosphorylation sites of FoxO1 were confirmed to be regulated by AKT and mediated the glucose metabolism. In conclusion, activation of insulin-AKT-FoxO1 pathway improved glucose tolerance through mediating glucose metabolism in largemouth bass.

DRD4 Mitigates Myocardial Ischemia/Reperfusion Injury in Association With PI3K/AKT Mediated Glucose Metabolism.

Ischemia-reperfusion (I/R) could cause heart irreversible damage, which is tightly combined with glucose metabolism disorder. It is demonstrated that GLUT4 (glucose transporter 4) translocation is critical for glucose metabolism in the cardiomyocytes under I/R injury. Moreover, DRD4 (dopamine receptor D4) modulate glucose metabolism, and protect neurocytes from anoxia/reoxygenation (A/R) injury. Thus, DRD4 might regulate myocardial I/R injury in association with GLUT4-mediated glucose metabolism. However, the effects and mechanisms are largely unknown. In the present study, the effect of DRD4 in heart I/R injury were studied ex vivo and in vitro. For I/R injury ex vivo, DRD4 agonist (PD168077) was perfused by Langendorff system in the isolated rat heart. DRD4 activated by PD168077 improved cardiac function in the I/R-injured heart as determined by the left ventricular developed pressure (LVDP), +dp/dt, and left ventricular end diastolic pressure (LVEDP), and reduced heart damage evidenced by infarct size, the release of troponin T (TNT) and lactate dehydrogenase (LDH). DRD4 activation diminished I/R injury induced apoptosis and enhanced cell viability impaired by I/R injury in cardiomyocyte, showed by TUNEL staining, flow cytometer and CCK8 assay. Furthermore, DRD4 activation did not change total GULT4 protein expression level but increased the membrane GULT4 localization determined by western blot. In terms of mechanism, DRD4 activation increased pPI3K/p-AKT but not the total PI3K/AKT during anoxia/reoxygenation (A/R) injury in vitro. Interestingly, PI3K inhibitor, Wortmannin, blocked PI3K/AKT pathway and depleted the membrane GULT4, and further promoted apoptosis showed by TUNEL staining, flow cytometer, western blot of cleaved caspase 3, BAX and BCL2 expression. Thus, DRD4 activation exerted a protective effect against I/R injury by promoting GLUT4 translocation depended on PI3K/AKT pathway, which enhanced the ability of glucose uptake, and ultimately reduced the apoptosis in cardiomyocytes.