Discovery of 12ß-oxygenated oleanolic acid alkyl esters as potent and selective FXR modulators exhibiting hyperglycemia amelioration in vivo.

Farnesoid X receptor (FXR) ligands have been actively pursued to treat metabolic disorders, liver and bile diseases, among others. Starting from a widely occurring natural product, oleanolic acid (OA), we discovered potent and selective FXR modulator from the 12ß-oxygenated OA alkyl esters, with the assistance of molecular modeling. The representative compound 7b modulated some FXR downstream genes involved in glucose and lipid metabolism in cells, and significantly improved hyperglycemia in KKay fat mice fed with high fat diet, through the reduction of mRNA expression of gluconeogenesis genes PEPCK and G6Pase. This study provides a new series of selective FXR modulator, as well as the in vitro and in vivo evidence for their potential to improve hyperglycemia in diabetic mice through FXR antagonism.

Shenqi compound ameliorates type-2 diabetes mellitus by modulating the gut microbiota and metabolites.

The gut microbiota (GM) and metabolites are important factors in mediating the development of type-2 diabetes mellitus (T2DM). An imbalance in the gut microbiota and metabolites can disrupt the function of the intestinal barrier, cause changes in the permeability of the intestinal mucosa and promote the immune inflammatory response, thereby aggravating the fluctuation of blood glucose level and promoting the occurrence and development of the chronic complications of DM. Manipulating the GM and metabolites is a promising therapeutic intervention and is being studied extensively. Shenqi compound (SQC) is a traditional Chinese medicine formulation, which has been widely used to improve T2DM. Studies have demonstrated that SQC can reduce glycemic variability, alleviate the inflammatory response, etc. However, its underlying mechanism remains unknown. Therefore, in this experiment, We administered SQC to Goto-Kakizaki (GK) rats and evaluated its effect on blood glucose homeostasis and the intestinal mucosal barrier. We identified the profiles of the GM and metabolites with the aid of 16S rDNA gene sequencing and non-target metabolomics analysis. It showed that SQC intervention could reduce glycemic variability, regulate serum levels of glucagon and insulin, and improve injury to the intestinal mucosal barrier of GK rats. In the gut, the ratio of bacteria of the phyla Bacteroidetes/Firmicutes could be improved after SQC intervention. SQC also regulated the relative abundance of Prevotellaceae, Butyricimonas, Bacteroides, Blautia, Roseburia, Lactobacillus, and Rothia. We found out that expression of 40 metabolites was significantly improved after SQC intervention. Further analyses of metabolic pathways indicated that the therapeutic effect of SQC might be related predominantly to its ability to improve gluconeogenesis/glycolysis, amino acid metabolism, lipid metabolism, citrate cycle, and butanoate metabolism. These results suggest that SQC may exert a beneficial role in T2DM by modulating the GM and metabolites in different pathways.

GP73 is a glucogenic hormone contributing to SARS-CoV-2-induced hyperglycemia.

Severe cases of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are associated with elevated blood glucose levels and metabolic complications. However, the molecular mechanisms for how SARS-CoV-2 infection alters glycometabolic control are incompletely understood. Here, we connect the circulating protein GP73 with enhanced hepatic gluconeogenesis during SARS-CoV-2 infection. We first demonstrate that GP73 secretion is induced in multiple tissues upon fasting and that GP73 stimulates hepatic gluconeogenesis through the cAMP/PKA signaling pathway. We further show that GP73 secretion is increased in cultured cells infected with SARS-CoV-2, after overexpression of SARS-CoV-2 nucleocapsid and spike proteins and in lungs and livers of mice infected with a mouse-adapted SARS-CoV-2 strain. GP73 blockade with an antibody inhibits excessive glucogenesis stimulated by SARS-CoV-2 in vitro and lowers elevated fasting blood glucose levels in infected mice. In patients with COVID-19, plasma GP73 levels are elevated and positively correlate with blood glucose levels. Our data suggest that GP73 is a glucogenic hormone that likely contributes to SARS-CoV-2-induced abnormalities in systemic glucose metabolism.

Jieduquyuziyin Prescription alleviates hepatic gluconeogenesis via PI3K/Akt/PGC-1α pathway in glucocorticoid-induced MRL/lpr mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Jieduquyuziyin prescription (JP) is a traditional Chinese medicine (TCM) formula. According to both TCM theory and more than a decade of clinical practice, JP has been testified to be effective for systemic lupus erythematosus (SLE) treatment as an approved hospital prescription in China. AIM OF THE STUDY: To determine the effect of JP on the treatment of SLE by glucocorticoid (GC) and to further examine the molecular mechanisms. MATERIALS AND METHODS: We conducted in vivo experiments to estimate the effect of JP on hepatic gluconeogenesis in MRL/lpr mice treated with GC. Additionally, isoproterenol (ISO) induced hepatic gluconeogenesis model and GC-treated MRL/lpr mouse hepatocytes were carried out in vitro experiments to verify the effect of JP on gluconeogenesis. RESULTS: The results showed that JP combined with GC could effectively alleviate the lupus symptoms in MRL/lpr mice and improve the pathological changes of the kidney and liver. And the combination of JP reduced the side effects caused by GC, which was related to the inhibition of GC-induced hepatic gluconeogenesis in MRL/lpr mice. Specifically, JP up-regulated the expression of glucocorticoid receptor (GR) α, phosphoinositide-3-kinase (PI3K) and Akt restrained by GC to reduce the production of forkhead box O1 (FoxO1), peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α), and the gluconeogenic genes phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase). In vivo, the use of JP either alone or with GC could reduce spleen enlargement, high levels of serum antibodies, aggravated urine protein and renal pathological damage in MRL/lpr mice. Furthermore, the glucose content was reduced in the liver of MRL/lpr mice treated with JP, and the liver damage and steatosis were also alleviated. In vitro, the expressions of PI3K and Akt increased and the expressions of FoxO1, PGC-1α, PEPCK and G6Pase decreased after JP treatment in ISO-treated hepatocytes. Compared with MRL/MP mice, we found that JP could significantly inhibit the expression of gluconeogenesis in the hepatocytes of MRL/lpr mice induced by GC to a greater extent. CONCLUSIONS: The therapeutic effect of JP on GC-induced is likely related to hepatic gluconeogenesis, which provides a new perspective to reveal the positive role of JP in SLE.

Propofol ameliorates acute postoperative fatigue and promotes glucagon-regulated hepatic gluconeogenesis by activating CREB/PGC-1α and accelerating fatty acids beta-oxidation.

Postoperative fatigue (POF) is the most common and long-lasting complication after surgery, which brings heavy burden to individuals and society. Recently, hastening postoperative recovery receives increasing attention, but unfortunately, the mechanisms underlying POF remain unclear. Propofol is a wildly used general anesthetic in clinic, and inspired by the rapid antidepressant effects induced by ketamine at non-anesthetic dose, the present study was undertaken to investigate the anti-fatigue effects and underlying mechanisms of propofol at a non-anesthetic dose in 70% hepatectomy induced POF model in rats. We first showed here that single administration of propofol at 0.1 mg/kg ameliorated acute POF in hepatectomy induced POF rats. Based on metabonomics analysis, we hypothesized that propofol exerted anti-fatigue activity in POF rats by facilitating free fatty acid (FFA) oxidation and gluconeogenesis. We further confirmed that propofol restored the deficit in FFA oxidation and gluconeogenesis in POF rats, as evidenced by the elevated FFA utilization, acetyl coenzyme A content, pyruvic acid content, phosphoenolpyruvic acid content, hepatic glucose output and glycogen storage. Moreover, propofol stimulated glucagon secretion and up-regulated expression of cAMP-response element binding protein (CREB), phosphorylated CREB, peroxlsome prolifeator-activated receptor-γ coactivator-1α (PGC-1α), phosphoenolpyruvate carboxykinade1 and carnitine palmitoltransferase 1A. In summary, our study suggests for the first time that propofol ameliorates acute POF by promoting glucagon-regulated gluconeogenesis via CREB/PGC-1α signaling and accelerating FFA beta-oxidation.

PCB126 induced toxic actions on liver energy metabolism is mediated by AhR in rats.

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor involved in the regulation of biological responses to more planar aromatic hydrocarbons, like TCDD. We previously described the sequence of events following exposure of male rats to a dioxin-like polychlorinated biphenyl (PCB) congener, 3,3',4,4',5-pentachlorobiphenyl (PCB126), that binds avidly to the AhR and causes various types of toxicity including metabolic syndrome, fatty liver, and disruption of energy homeostasis. The purpose of this study was, to investigate the role of AhR to mediate those toxic manifestations following sub-acute exposure to PCB126 and to examine possible sex differences in effects. For this goal, we created an AhR knockout (AhR-KO) model using CRISPR/Cas9. Comparison was made to the wild type (WT) male and female Holtzman Sprague Dawley rats. Rats were injected with a single IP dose of corn oil vehicle or 5 µmol/kg PCB126 in corn oil and necropsied after 28 days. PCB126 caused significant weight loss, reduced relative thymus weights, and increased relative liver weights in WT male and female rats, but not in AhR-KO rats. Similarly, significant pathologic changes were visible which included necrosis and regeneration in female rats, micro- and macro-vesicular hepatocellular vacuolation in males, and a paucity of glycogen in livers of both sexes in WT rats only. Hypoglycemia and lower IGF1, and reduced serum non-esterified fatty acids (NEFAs) were found in serum of both sexes of WT rats, low serum cholesterol levels only in the females, and no changes in AhR-KO rats. The expression of genes encoding enzymes related to xenobiotic metabolism (e.g. CYP1A1), gluconeogenesis, glycogenolysis, and fatty acid oxidation were unaffected in the AhR-KO rats following PCB126 exposure as opposed to WT rats where expression was significantly upregulated (PPARα, females only) or downregulated suggesting a disrupted energy homeostasis. Interestingly, Acox2, Hmgcs, G6Pase and Pc were affected in both sexes, the gluconeogenesis and glucose transporter genes Pck1, Glut2, Sds, and Crem only in male WT-PCB rats. These results show the essential role of the AhR in glycogenolysis, gluconeogenesis, and fatty acid oxidation, i.e. in the regulation of energy production and homeostasis, but also demonstrate a significant difference in the effects of PCB126 in males verses females, suggesting higher vulnerability of glucose homeostasis in males and more changes in fatty acid/lipid homeostasis in females. These differences in effects, which may apply to more/all AhR agonists, should be further analyzed to identify health risks to specific groups of highly exposed human populations.

Integrated or Independent Actions of Metformin in Target Tissues Underlying Its Current Use and New Possible Applications in the Endocrine and Metabolic Disorder Area.

Metformin is considered the first-choice drug for type 2 diabetes treatment. Actually, pleiotropic effects of metformin have been recognized, and there is evidence that this drug may have a favorable impact on health beyond its glucose-lowering activity. In summary, despite its long history, metformin is still an attractive research opportunity in the field of endocrine and metabolic diseases, age-related diseases, and cancer. To this end, its mode of action in distinct cell types is still in dispute. The aim of this work was to review the current knowledge and recent findings on the molecular mechanisms underlying the pharmacological effects of metformin in the field of metabolic and endocrine pathologies, including some endocrine tumors. Metformin is believed to act through multiple pathways that can be interconnected or work independently. Moreover, metformin effects on target tissues may be either direct or indirect, which means secondary to the actions on other tissues and consequent alterations at systemic level. Finally, as to the direct actions of metformin at cellular level, the intracellular milieu cooperates to cause differential responses to the drug between distinct cell types, despite the primary molecular targets may be the same within cells. Cellular bioenergetics can be regarded as the primary target of metformin action. Metformin can perturb the cytosolic and mitochondrial NAD/NADH ratio and the ATP/AMP ratio within cells, thus affecting enzymatic activities and metabolic and signaling pathways which depend on redox- and energy balance. In this context, the possible link between pyruvate metabolism and metformin actions is extensively discussed.

Licochalcone A activation of glycolysis pathway has an anti-aging effect on human adipose stem cells.

Licochalcone A (LA) is a chalcone flavonoid of Glycyrrhiza inflata, which has anti-cancer, antioxidant, anti-inflammatory, and neuroprotective effects. However, no anti-aging benefits of LA have been demonstrated in vitro or in vivo. In this study, we explored whether LA has an anti-aging effect in adipose-derived stem cells (ADSCs). We performed ß-galactosidase staining and measured reactive oxygen species, relative telomere lengths, and P16ink4a mRNA expression. Osteogenesis was assessed by Alizarin Red staining and adipogenesis by was assessed Oil Red O staining. Protein levels of related markers runt-related transcription factor 2 and lipoprotein lipase were also examined. RNA sequencing and measurement of glycolysis activities showed that LA significantly activated glycolysis in ADSCs. Together, our data strongly suggest that the LA have an anti-aging effect through activate the glycolysis pathway.

Complex Positive Effects of SGLT-2 Inhibitor Empagliflozin in the Liver, Kidney and Adipose Tissue of Hereditary Hypertriglyceridemic Rats: Possible Contribution of Attenuation of Cell Senescence and Oxidative Stress.

(1) Background: empagliflozin, sodium-glucose co-transporter 2 (SGLT-2) inhibitor, is an effective antidiabetic agent with strong cardio- and nephroprotective properties. The mechanisms behind its cardio- and nephroprotection are still not fully clarified. (2) Methods: we used male hereditary hypertriglyceridemic (hHTG) rats, a non-obese model of dyslipidaemia, insulin resistance, and endothelial dysfunction fed standard diet with or without empagliflozin for six weeks to explore the molecular mechanisms of empagliflozin effects. Nuclear magnetic resonance (NMR)-based metabolomics; quantitative PCR of relevant genes involved in lipid and glucose metabolism, or senescence; glucose and palmitic acid oxidation in isolated tissues and cell lines of adipocytes and hepatocytes were used. (3) Results: empagliflozin inhibited weight gain and decreased adipose tissue weight, fasting blood glucose, and triglycerides and increased HDL-cholesterol. It also improved insulin sensitivity in white fat. NMR spectroscopy identified higher plasma concentrations of ketone bodies, ketogenic amino acid leucine and decreased levels of pyruvate and alanine. In the liver, adipose tissue and kidney, empagliflozin up-regulated expression of genes involved in gluconeogenesis and down-regulated expression of genes involved in lipogenesis along with reduction of markers of inflammation, oxidative stress and cell senescence. (4) Conclusion: multiple positive effects of empagliflozin, including reduced cell senescence and oxidative stress, could contribute to its long-term cardio- and nephroprotective actions.

Embryonic Steroids Control Developmental Programming of Energy Balance.

Glucose is a major energy source for growth. At birth, neonates must change their energy source from maternal supply to its own glucose production. The mechanism of this transition has not been clearly elucidated. To evaluate the possible roles of steroids in this transition, here we examine the defects associated with energy production of a mouse line that cannot synthesize steroids de novo due to the disruption of its Cyp11a1 (cytochrome P450 family 11 subfamily A member 1) gene. The Cyp11a1 null embryos had insufficient blood insulin and failed to store glycogen in the liver since embryonic day 16.5. Their blood glucose dropped soon after maternal deprivation, and the expression of hepatic gluconeogenic and glycogenic genes were reduced. Insulin was synthesized in the mutant fetal pancreas but failed to be secreted. Maternal glucocorticoid supply rescued the amounts of blood glucose, insulin, and liver glycogen in the fetus but did not restore expression of genes for glycogen synthesis, indicating the requirement of de novo glucocorticoid synthesis for glycogen storage. Thus, our investigation of Cyp11a1 null embryos reveals that the energy homeostasis is established before birth, and fetal steroids are required for the regulation of glycogen synthesis, hepatic gluconeogenesis, and insulin secretion at the fetal stage.

Anti-inflammatory action of betulin and its potential as a dissociated glucocorticoid receptor modulator.

Although the medical application of betulin has been presented in previous studies, the potential mechanism of the anti-inflammatory action of betulin should be further investigated. This work aims to confirm the hypothesis that betulin has dexamethasone-like anti-inflammatory action through glucocorticoid receptor (GR)-mediated pathway. Firstly, the binding ability of betulin with GR was measured by a fluorescence polarization-based competitive binding assay, with the IC50 value of 79.18 ± 0.30 mM. Betulin could bind to GR and then induced GR nuclear translocation, but lacked GR transcriptional activity in HeLa cells. Hence, betulin exhibited the potential to be a dissociated modulator for GR, with the loss of glucocorticoid response element (GRE)-associated side effects. In addition, betulin downregulated GRE-driven protein expression of G6P involved in gluconeogenesis, namely side effect. The results of pro-inflammatory cytokines analysis showed that betulin exerted anti-inflammatory action in vitro. Both of the hydrophobic and hydrogen-bonding interactions stabilized the binding between betulin and GR during the simulation process. In conclusion, betulin might be a potential dissociated GR modulator with a reduced side effect profile yet keeping its anti-inflammatory action.

Loureirin B attenuates insulin resistance in HepG2 cells by regulating gluconeogenesis signaling pathway.

Insulin resistance (IR) is the main cause of type 2 diabetes. The liver is the organ where insulin is secreted from the pancreas, and it regulates the storage and release of glucose according to the body's demand. Althouth Loureirin B (LB) has been reported to promote insulin secretion and decrease blood glucose, the effects of LB on glucose metabolism in the liver and the mechanism is still unclear. Different concentrations of LB were applied to treat on insulin resistance model (IR-HepG2) cells. The research results showed that LB inhibited the production of ROS (Reactive oxygen species) in IR-HepG2 cells, promoted the phosphorylation of AKT, down-regulated the expression of FoxO1, and up-regulated the expression of IRS1 and GLUT4. In addition, LB also down regulated the glucose metabolism related genes PEPCK and GSK3ß. The glucose uptake, consumption and glycogen content were increased. Moreover, LB-treated diabetic mice also showed hypoglycaemic effects. In summary, LB may ameliorate type 2 diabetes by preventing the inactivation of IRS1/AKT pathway in IR-HepG2 cells, increasing insulin sensitivity, and regulating glucose uptake and production.

New Insight into the Effects of Metformin on Diabetic Retinopathy, Aging and Cancer: Nonapoptotic Cell Death, Immunosuppression, and Effects beyond the AMPK Pathway.

Under metabolic stress conditions such as hypoxia and glucose deprivation, an increase in the AMP:ATP ratio activates the AMP-activated protein kinase (AMPK) pathway, resulting in the modulation of cellular metabolism. Metformin, which is widely prescribed for type 2 diabetes mellitus (T2DM) patients, regulates blood sugar by inhibiting hepatic gluconeogenesis and promoting insulin sensitivity to facilitate glucose uptake by cells. At the molecular level, the most well-known mechanism of metformin-mediated cytoprotection is AMPK pathway activation, which modulates metabolism and protects cells from degradation or pathogenic changes, such as those related to aging and diabetic retinopathy (DR). Recently, it has been revealed that metformin acts via AMPK- and non-AMPK-mediated pathways to exert effects beyond those related to diabetes treatment that might prevent aging and ameliorate DR. This review focuses on new insights into the anticancer effects of metformin and its potential modulation of several novel types of nonapoptotic cell death, including ferroptosis, pyroptosis, and necroptosis. In addition, the antimetastatic and immunosuppressive effects of metformin and its hypothesized mechanism are also discussed, highlighting promising cancer prevention strategies for the future.

Androgen-induced insulin resistance is ameliorated by deletion of hepatic androgen receptor in females.

Androgen excess is one of the most common endocrine disorders of reproductive-aged women, affecting up to 20% of this population. Women with elevated androgens often exhibit hyperinsulinemia and insulin resistance. The mechanisms of how elevated androgens affect metabolic function are not clear. Hyperandrogenemia in a dihydrotestosterone (DHT)-treated female mouse model induces whole body insulin resistance possibly through activation of the hepatic androgen receptor (AR). We investigated the role of hepatocyte AR in hyperandrogenemia-induced metabolic dysfunction by using several approaches to delete hepatic AR via animal-, cell-, and clinical-based methodologies. We conditionally disrupted hepatocyte AR in female mice developmentally (LivARKO) or acutely by tail vein injection of an adeno-associated virus with a liver-specific promoter for Cre expression in ARfl/fl mice (adLivARKO). We observed normal metabolic function in littermate female Control (ARfl/fl ) and LivARKO (ARfl/fl ; Cre+/- ) mice. Following chronic DHT treatment, female Control mice treated with DHT (Con-DHT) developed impaired glucose tolerance, pyruvate tolerance, and insulin tolerance, not observed in LivARKO mice treated with DHT (LivARKO-DHT). Furthermore, during an euglycemic hyperinsulinemic clamp, the glucose infusion rate was improved in LivARKO-DHT mice compared to Con-DHT mice. Liver from LivARKO, and primary hepatocytes derived from LivARKO, and adLivARKO mice were protected from DHT-induced insulin resistance and increased gluconeogenesis. These data support a paradigm in which elevated androgens in females disrupt metabolic function via hepatic AR and insulin sensitivity was restored by deletion of hepatic AR.

O-GlcNAcylated p53 in the liver modulates hepatic glucose production.

p53 regulates several signaling pathways to maintain the metabolic homeostasis of cells and modulates the cellular response to stress. Deficiency or excess of nutrients causes cellular metabolic stress, and we hypothesized that p53 could be linked to glucose maintenance. We show here that upon starvation hepatic p53 is stabilized by O-GlcNAcylation and plays an essential role in the physiological regulation of glucose homeostasis. More specifically, p53 binds to PCK1 promoter and regulates its transcriptional activation, thereby controlling hepatic glucose production. Mice lacking p53 in the liver show a reduced gluconeogenic response during calorie restriction. Glucagon, adrenaline and glucocorticoids augment protein levels of p53, and administration of these hormones to p53 deficient human hepatocytes and to liver-specific p53 deficient mice fails to increase glucose levels. Moreover, insulin decreases p53 levels, and over-expression of p53 impairs insulin sensitivity. Finally, protein levels of p53, as well as genes responsible of O-GlcNAcylation are elevated in the liver of type 2 diabetic patients and positively correlate with glucose and HOMA-IR. Overall these results indicate that the O-GlcNAcylation of p53 plays an unsuspected key role regulating in vivo glucose homeostasis.

Aloe vera carbohydrates regulate glucose metabolism through improved glycogen synthesis and downregulation of hepatic gluconeogenesis in diabetic rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Aloe vera (L.) Burm.f. is an ancient medicinal plant that belongs to the family Asphodelaceae. It has a rich source of bioactive constituents such as carbohydrates, polyphenols, peptides, sterols and tannins, etc. Aloe vera has multiple biological activities such as anti-inflammatory, antioxidant and antidiabetic activity etc. AIM OF THE STUDY: The present study investigated the antidiabetic mechanism of Aloe vera carbohydrate fraction (AVCF) and aimed to provide insights into the regulation of carbohydrate metabolism enzymes in glucose homeostasis. MATERIALS AND METHODS: The antidiabetic effect of AVCF was evaluated using α-amylase, α-glucosidase inhibition, glucose diffusion and glucose uptake assay. The in vitro AVCF effect on insulin secretion, cell proliferation and inflammatory markers were determined using streptozotocin-induced oxidative stress on RIN-m5F cells. Streptozotocin-induced male Wistar diabetic rats were treated for 21 days with AVCF (54 mg/kg bw). The in vivo AVCF effect was measured on fasting plasma glucose, insulin, glucagon, hexokinase, glycogen synthase and glucose-6-phosphatase, levels in diabetic rats. Histopathological studies for organ-specific effects in the pancreas, liver and small intestine were also conducted. RESULTS: AVCF-treated RIN-m5F cells significantly increased BrdU levels, with insulin secretion, and decreased TNF-α, IL-6 and nitric oxide levels. AVCF treated streptozotocin-induced diabetic rats showed significantly decreased fasting plasma glucose, glucagon and glucose-6-phosphatase levels with a concomitant increase in insulin, hexokinase, and glycogen synthase levels and, glycogen content. These findings corroborate with the improved hepatic glycogen content in the PAS stained histological section of the liver of AVCF treated diabetic rats. CONCLUSION: These results suggest that CF of Aloe vera improved glucose metabolism by activation of glycogenesis and down-regulation of gluconeogenesis thereby, maintaining glucose homeostasis. Hence, AVCF can be used as an alternative medicine in the alleviation of diabetes mellitus symptoms.

Sodium hydrosulfide has no additive effects on nitrite-inhibited renal gluconeogenesis in type 2 diabetic rats.

OBJECTIVE: Increased renal and hepatic gluconeogenesis are important sources of fasting hyperglycemia in type 2 diabetes (T2D). The inhibitory effect of co-administration of sodium nitrite and sodium hydrosulfide (NaSH) on hepatic but not renal gluconeogenesis has been reported in rats with T2D. The present study aimed to determine the effects of co-administration of sodium nitrite and NaSH on the expression of genes involved in renal gluconeogenesis in rats with T2D. METHODS: T2D was induced by a combination of a high-fat diet and low-dose streptozotocin (30 mg/kg). Male Wistar rats were divided into 5 groups (n = 6/group): Control, T2D, T2D + nitrite, T2D + NaSH, and T2D + nitrite+NaSH. Nitrite and NaSH were administered for nine weeks at a dose of 50 mg/L (in drinking water) and 0.28 mg/kg (daily intraperitoneal injection), respectively. Serum levels of urea and creatinine, and mRNA expressions of PEPCK, G6Pase, FBPase, PC, PI3K, AKT, PGC-1α, and FoxO1 in the renal tissue, were measured at the end of the study. RESULTS: Nitrite decreased mRNA expression of PEPCK by 39%, G6Pase by 43%, FBPase by 41%, PC by 63%, PGC-1α by 45%, and FoxO1 by 27% in the renal tissue of rats with T2D; co-administration of nitrite and NaSH further decreases FoxO1, while had no additive effects on the tissue expression of the other genes. In addition, nitrite+NaSH decreased elevated serum urea levels by 58% and creatinine by 37% in rats with T2D. CONCLUSION: The inhibitory effect of nitrite on gluconeogenesis in T2D rats is at least in part due to decreased mRNA expressions of renal gluconeogenic genes. Unlike effects on hepatic gluconeogenesis, co-administration of nitrite and NaSH has no additive effects on genes involved in renal gluconeogenesis in rats with T2D.

Pan2-Pan3 complex, together with Ccr4-Not complex, has a role in the cell growth on non-fermentable carbon sources.

There are two major deadenylase complexes, Ccr4-Not and Pan2-Pan3, which shorten the 3' poly(A) tail of mRNA and are conserved from yeast to human. We have previously shown that the Ccr4-mediated deadenylation plays the important role in gene expression regulation in the yeast stationary phase cell. In order to further understand the role of deadenylases in different growth condition, in this study we investigated the effect of deletion of both deadenylases on the cell in non-fermentable carbon containing media. We found that both ccr4Δ and ccr4Δ pan2Δ mutants showed similar growth defect in YPD media: when switched to media containing non-fermentable source (Glycerol-Lactate) only the ccr4Δ grew while the ccr4Δ pan2Δ did not. Ccr4, Pan2, and Pan3 were phosphorylated in GlyLac medium, suggesting that the activities of Ccr4, Pan2, and Pan3 may be regulated by phosphorylation in response to change of carbon sources. To get insights how Ccr4 and Pan2 function in the cell growth in media containing non-fermentable source only, we isolated multicopy suppressors for the growth defect on YPGlyLac media of the ccr4Δ pan2Δ mutant and identified two genes, STM1 and REX2, which encode a ribosome-associated protein and a 3'-5' RNA exonuclease, respectively. Our results suggest that the Pan2-Pan3 complex, together with the Ccr4-Not complex, has important roles in the growth on non-fermentable carbon sources.

Metformin Targets Foxo1 to Control Glucose Homeostasis.

Metformin is the first-line pharmacotherapy for type 2 diabetes mellitus (T2D). Metformin exerts its glucose-lowering effect primarily through decreasing hepatic glucose production (HGP). However, the precise molecular mechanisms of metformin remain unclear due to supra-pharmacological concentration of metformin used in the study. Here, we investigated the role of Foxo1 in metformin action in control of glucose homeostasis and its mechanism via the transcription factor Foxo1 in mice, as well as the clinical relevance with co-treatment of aspirin. We showed that metformin inhibits HGP and blood glucose in a Foxo1-dependent manner. Furthermore, we identified that metformin suppresses glucagon-induced HGP through inhibiting the PKA→Foxo1 signaling pathway. In both cells and mice, Foxo1-S273D or A mutation abolished the suppressive effect of metformin on glucagon or fasting-induced HGP. We further showed that metformin attenuates PKA activity, decreases Foxo1-S273 phosphorylation, and improves glucose homeostasis in diet-induced obese mice. We also provided evidence that salicylate suppresses HGP and blood glucose through the PKA→Foxo1 signaling pathway, but it has no further additive improvement with metformin in control of glucose homeostasis. Our study demonstrates that metformin inhibits HGP through PKA-regulated transcription factor Foxo1 and its S273 phosphorylation.

Chitosan Oligosaccharide Alleviates Abnormal Glucose Metabolism without Inhibition of Hepatic Lipid Accumulation in a High-Fat Diet/Streptozotocin-Induced Diabetic Rat Model.

This study investigated the effects of chitosan oligosaccharide (COS) on glucose metabolism and hepatic steatosis in a high-fat (HF) diet/streptozotocin-induced diabetic rat model. Male Wistar rats were divided into: (1) normal control (NC group), (2) HF diet (HF group), (3) streptozotocin (STZ)-induced diabetes with HF diet (DF group), and DF group supplemented with (4) 0.5% COS (D0.5F group), (5) 1% COS (D1F group), and (6) 5% COS (D5F group) for 4 weeks. COS supplementation significantly decreased the plasma glucose, BUN, creatinine, uric acid, triglyceride (TG), and total cholesterol (TC) levels, and hepatic glucose-6-phosphatase activity, and significantly increased hepatic hexokinase activity and glycogen content in diabetic rats; but the increased hepatic TG and TC levels could not be significantly decreased by COS supplementation. Supplementation of COS increased superoxide dismutase activity and decreased lipid peroxidation products in the diabetic rat livers. COS supplementation significantly increased phosphorylated AMP-activated protein kinase (AMPK) protein expression, and attenuated protein expression of hepatic phosphoenolpyruvate carboxykinase (PEPCK) and phosphorylated p38 and renal sodium-glucose cotransporter-2 (SGLT2) in diabetic rats. These results suggest that COS may possess a potential for alleviating abnormal glucose metabolism in diabetic rats through the inhibition of hepatic gluconeogenesis and lipid peroxidation and renal SGLT2 expression.