Reduction In Glucose Production Research Articles

Hypoxanthine ameliorates diet-induced insulin resistance by improving hepatic lipid metabolism and gluconeogenesis via AMPK/mTOR/PPARα pathway

AimInsulin resistance (IR) is a pivotal metabolic disorder associated with type 2 diabetes and metabolic syndrome. This study investigated the potential of hypoxanthine (Hx), a purine metabolite and uric acid precursor, in ameliorating IR and regulating hepatic glucose and lipid metabolism. MethodsWe utilized both in vitro IR-HepG2 cells and in vivo diet-induced IR mice to investigate the impact of Hx. The HepG2 cells were treated with Hx to evaluate its effects on glucose production and lipid deposition. Activity-based protein profiling (ABPP) was applied to identify Hx-target proteins and the underlying pathways. In vivo studies involved administration of Hx to IR mice, followed by assessments of IR-associated indices, with explores on the potential regulating mechanisms on hepatic glucose and lipid metabolism. Key findingsHx intervention significantly reduced glucose production and lipid deposition in a dose-dependent manner without affecting cell viability in IR-HepG2 cells. ABPP identified key Hx-target proteins engaged in fatty acid and pyruvate metabolism. In vivo, Hx treatment reduced IR severities, as evidenced by decreased HOMA-IR, fasting blood glucose, and serum lipid profiles. Histological assessments confirmed reduced liver lipid deposition. Mechanistic insights revealed that Hx suppresses hepatic gluconeogenesis and fatty acid synthesis, and promotes fatty acid oxidation via the AMPK/mTOR/PPARα pathway. SignificanceThis study delineates a novel role of Hx in regulating hepatic metabolism, offering a potential therapeutic strategy for IR and associated metabolic disorders. The findings provide a foundation for further investigation into the role of purine metabolites in metabolic regulation and their clinical implications.

Plant-Derived Flavonoids as AMPK Activators: Unveiling Their Potential in Type 2 Diabetes Management through Mechanistic Insights, Docking Studies, and Pharmacokinetics

Type 2 diabetes mellitus (T2DM) remains a significant global health issue, marked by insulin resistance and disrupted glucose metabolism. AMP-activated protein kinase (AMPK) serves as a key regulator of cellular energy balance, playing a crucial role in enhancing insulin sensitivity, promoting glucose uptake, and reducing glucose production in the liver. Recently, there has been growing interest in plant-derived flavonoids as natural activators of AMPK, offering a promising complementary approach to conventional diabetes treatments. This review delves into ten flavonoids identified as AMPK activators, including baicalein, dihydromyricetin, bavachin, 7-O-MA, derrone, and alpinumisoflavone. Their activation mechanisms are explored, which include both direct binding to the AMPK complex and indirect pathways involving upstream signaling. Through molecular docking studies, the binding affinities and interaction profiles of these flavonoids with AMPK are assessed, revealing varying levels of activation potential. Notably, baicalein and dihydromyricetin showed strong binding to the α1 subunit of AMPK, indicating high potential for robust activation. Additionally, this review provides a thorough analysis of the pharmacokinetic properties and drug-likeness of these flavonoids using the SwissADME tool, focusing on aspects such as ADME (Absorption, Distribution, Metabolism, and Excretion). While the overall profiles of these compounds are promising, issues like solubility and possible drug–drug interactions are areas that need further refinement. In summary, plant-derived flavonoids emerge as a promising avenue for developing new natural therapies for T2DM. Moving forward, research should aim at optimizing these compounds for clinical application, elucidating their specific mechanisms of AMPK activation, and confirming their efficacy in T2DM treatment. This review highlights the potential of flavonoids as safer and more holistic alternatives or adjuncts to current diabetes therapies.

Modern Challenges in Type 2 Diabetes: Balancing New Medications with Multifactorial Care.

Type 2 diabetes mellitus (T2DM) is a prevalent chronic metabolic disorder characterized by insulin resistance and progressive beta cell dysfunction, presenting substantial global health and economic challenges. This review explores recent advancements in diabetes management, emphasizing novel pharmacological therapies and their physiological mechanisms. We highlight the transformative impact of Sodium-Glucose Cotransporter 2 inhibitor (SGLT2i) and Glucagon-Like Peptide 1 Receptor Agonist (GLP-1RA), which target specific physiological pathways to enhance glucose regulation and metabolic health. A key focus of this review is tirzepatide, a dual agonist of the glucose-dependent insulinotropic polypeptide (GIP) and GLP-1 receptors. Tirzepatide illustrates how integrating innovative mechanisms with established physiological pathways can significantly improve glycemic control and support weight management. Additionally, we explore emerging treatments such as glimins and glucokinase activators (GKAs), which offer novel strategies for enhancing insulin secretion and reducing glucose production. We also address future perspectives in diabetes management, including the potential of retatrutide as a triple receptor agonist and evolving guidelines advocating for a comprehensive, multifactorial approach to care. This approach integrates pharmacological advancements with essential lifestyle modifications-such as dietary changes, physical activity, and smoking cessation-to optimize patient outcomes. By focusing on the physiological mechanisms of these new therapies, this review underscores their role in enhancing T2DM management and highlights the importance of personalized care plans to address the complexities of the disease. This holistic perspective aims to improve patient quality of life and long-term health outcomes.

Metformin: An overview

Metformin is a widely prescribed medication for managing type 2 diabetes mellitus, a chronic condition characterized by high blood sugar levels. It belongs to the biguanide class of drugs and is often considered a first-line treatment due to its effectiveness, safety profile, and relatively low cost.The primary mechanism of metformin involves reducing glucose production in the liver while increasing insulin sensitivity in peripheral tissues, such as muscles and fat cells. This results in better glucose utilization by the body, leading to lower blood sugar levels. Additionally, metformin may also have some modest effects on reducing appetite and promoting weight loss, making it beneficial for overweight or obese individuals with diabetes.Beyondits role in diabetes management, metformin has gained attention for its potential benefits in other health conditions. Some research suggests that it may have anti-inflammatory and anti-cancer properties, although further studies are needed to confirm these effects.While metformin is generally well-tolerated, it can cause gastrointestinal side effects such as nausea, diarrhea, and abdominal discomfort, particularly when starting treatment or with higher doses. In rare cases, it may also lead to a serious condition called lactic acidosis, especially in individuals with kidney or liver impairment. Metformin is usually taken orally in tablet form, typically one to three times daily with meals. Dosage may vary depending on individual factors such as kidney function, age, and other medical conditions. It's important for patients to regularly monitor their blood sugar levels and adhere to their prescribed treatment regimen while taking metformin.Overall, metformin remains a cornerstone in the management of type 2 diabetes and continues to be a subject of research for its potential benefits beyond glycemic control.

MicroRNA-721 regulates gluconeogenesis via KDM2A-mediated epigenetic modulation in diet-induced insulin resistance in C57BL/6J mice

BackgroundAberrant gluconeogenesis is considered among primary drivers of hyperglycemia under insulin resistant conditions, with multiple studies pointing towards epigenetic dysregulation. Here we examine the role of miR-721 and effect of epigenetic modulator laccaic acid on the regulation of gluconeogenesis under high fat diet induced insulin resistance.ResultsReanalysis of miRNA profiling data of high-fat diet-induced insulin-resistant mice model, GEO dataset (GSE94799) revealed a significant upregulation of miR-721, which was further validated in invivo insulin resistance in mice and invitro insulin resistance in Hepa 1–6 cells. Interestingly, miR-721 mimic increased glucose production in Hepa 1–6 cells via activation of FOXO1 regulated gluconeogenic program. Concomitantly, inhibition of miR-721 reduced glucose production in palmitate induced insulin resistant Hepa 1–6 cells by blunting the FOXO1 induced gluconeogenesis. Intriguingly, at epigenetic level, enrichment of the transcriptional activation mark H3K36me2 got decreased around the FOXO1 promoter. Additionally, identifying targets of miR-721 using miRDB.org showed H3K36me2 demethylase KDM2A as a potential target. Notably, miR-721 inhibitor enhanced KDM2A expression which correlated with H3K36me2 enrichment around FOXO1 promoter and the downstream activation of the gluconeogenic pathway. Furthermore, inhibition of miR-721 in high-fat diet-induced insulin-resistant mice resulted in restoration of KDM2A levels, concomitantly reducing FOXO1, PCK1, and G6PC expression, attenuating gluconeogenesis, hyperglycemia, and improving glucose tolerance. Interestingly, the epigenetic modulator laccaic acid also reduced the hepatic miR-721 expression and improved KDM2A expression, supporting our earlier report that laccaic acid attenuates insulin resistance by reducing gluconeogenesis.ConclusionOur study unveils the role of miR-721 in regulating gluconeogenesis through KDM2A and FOXO1 under insulin resistance, pointing towards significant clinical and therapeutic implications for metabolic disorders. Moreover, the promising impact of laccaic acid highlights its potential as a valuable intervention in managing insulin resistance-associated metabolic diseases.Graphical

Exploring the potential for branched chain keto-acids to inhibit the mitochondrial pyruvate carrier

Metabolism of branched-chain amino acids (BCAAs) is often dysregulated in obesity and diabetes. To be oxidized, BCAAs are first converted to branched chain keto-acids (BCKAs), which are structurally similar to pyruvic acid. Previous studies have suggested that BCKAs inhibit the mitochondrial pyruvate carrier (MPC), particularly in hepatocytes, so we sought to investigate this further. Mitochondria were isolated from mouse liver and coupled pyruvate respiration was assessed before and after addition of either 100μM keto-leucine (alpha-ketoisocaproate), keto-isoleucine, keto-valine, an equimolar mixture of the 3 BCKAs, or NaCl control. Keto-leucine and the BCKA mixture reduced respiration by ~35%, but keto-isoleucine and keto-valine had no effect. This was repeated in mouse heart mitochondria, and again, only keto-leucine or the BCKA mixture reduced pyruvate respiration by ~30%. In comparison, 1μM of the synthetic MPC inhibitor UK-5099 reduced pyruvate respiration by 80%. In hepatocytes, most pyruvate is not oxidized but is carboxylated, which is an important first step for hepatic gluconeogenesis. Isolated hepatocytes were treated with pyruvate +/- BCKAs, and while UK-5099 reduced glucose production, none of the BCKAs had any effect. This experiment was repeated with 13C-pyruvate, and while UK-5099 reduced 13C enrichment into the hepatocyte TCA cycle, gluconeogenic intermediates, and glucose in the media, again none of the BCKAs had any effect. This lack of effect on gluconeogenesis may be due to the relatively mild inhibition and the ability of hepatocytes to perform pyruvate-alanine cycling to maintain some pyruvate carbon entry into the TCA cycle. Respiration was then assessed in MPC-deficient cardiac mitochondria, and keto-leucine and the BCKA mixture were no longer able to reduce pyruvate oxidation suggesting the effect is dependent on the MPC. Keto-leucine also had no effect on pyruvate dehydrogenase (PDH) activity of cardiac mitochondrial lysates, suggesting that the reduction in pyruvate oxidation is due to MPC inhibition and not reduced PDH activity. In a bioluminescent resonance energy transfer (BRET) assay which indicates inhibitor binding and MPC conformational change, while UK-5099 increased BRET, keto-leucine had no effect. Lastly, we hypothesized that rapid oxidation of the keto-leucine could explain the relatively mild inhibition of the MPC that we observe. Therefore, we repeated mitochondrial respiration studies in mitochondria isolated from PPM1K−/− mice which is the phosphatase that regulates the branched chain keto acid dehydrogenase (BCKDH) and BCKA oxidation. As expected, PPM1K−/− mitochondria displayed enhanced BCKDH phosphorylation, suggestive of inhibited BCKA oxidation. To our surprise, while pyruvate oxidation was inhibited by keto-leucine in WT mitochondria, this inhibition was completely lost in liver or heart mitochondria from PPM1K−/− mice. Altogether, these results suggest that a downstream metabolite of keto-leucine inhibits the MPC, via a mechanism that differs from synthetic MPC inhibitors. Ongoing studies are being performed to search for this downstream metabolite responsible for MPC inhibition. Saint Louis University School of Medicine internal sponsorship. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Retatruide' drug trial: A paradigm shift in Type 2 Diabetes management.

Type 2 diabetes mellitus (T2DM) is a chronic medical condition characterised by persistent hyperglycemia caused by insulin resistance and impaired beta cell function. Typically, it occurs in individuals aged 45 and above, but due to the growing prevalence of obesity and sedentary lifestyle, it is increasingly being diagnosed in younger adults and adolescents. A positive family history of T2DM and specific genes such as TCF7L2 and PPARG also play an essential role.[1] Consequently, persistent hyperglycemia in type 2 DM can give rise to a range of microvascular complications such as retinopathy, neuropathy and nephropathy and macrovascular complications such as coronary artery and cerebrovascular diseases. T2DM accounts for 90% of the cases of diabetes, raising concern among the healthcare sector worldwide. In 2017, approximately 462 million individuals were affected by type 2 DM, accounting for 6.28% of the world’s population. By 2030, it is estimated that the global prevalence will rise to 7079 individuals per 100,000.[2] To prevent the complications caused by T2DM, it is essential to prioritize glycemic control. First and foremost, effective dietary control is pivotal. It has been established that obesity in individuals with T2DM is closely associated with insulin resistance and defects in insulin secretions thus managing the calorie intake is mandatory. However, pharmacologic intervention with oral glucose-lowering agents or insulin therapy is necessary when the patient’s blood glucose doesn’t fall within normal limits despite weight reduction, exercise and dietary modifications. The first line pharmacological agent used is Metformin, an oral medication that reduces glucose production in the liver. Additionally, insulin secretagogues such as sulfonylureas and glinides promote insulin release by stimulating beta cells. Thiazolidinediones is another example of an oral agent used to treat diabetes by enhancing glucose uptake by the muscle, liver and adipose tissue.[3] Furthermore, it is crucial to understand that the Incretin effect, responsible for stimulating insulin secretion after meals, is primarily mediated by gut-derived incretin hormones known as glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1). However, patients with type 2 diabetes (T2DM) commonly exhibit defects in this process. To address this issue, in addition to oral medications, injectable drugs such as RA-GLP1 (Semaglutide, Dulaglutide) are administered to emulate the actions of human GLP-1 effectively. These injectable treatments are vital in reducing postprandial hyperglycemia and have become indispensable in managing T2DM. ---Continue

High-throughput screening identifies small molecule inhibitors of thioesterase superfamily member 1: Implications for the management of non-alcoholic fatty liver disease

ObjectiveThioesterase superfamily member 1 (Them1) is a long chain acyl-CoA thioesterase comprising two N-terminal HotDog fold enzymatic domains linked to a C-terminal lipid-sensing steroidogenic acute regulatory transfer-related (START) domain, which allosterically modulates enzymatic activity. Them1 is highly expressed in thermogenic adipose tissue, where it functions to suppress energy expenditure by limiting rates of fatty acid oxidation, and is induced markedly in liver in response to high fat feeding, where it suppresses fatty acid oxidation and promotes glucose production. Them1−/− mice are protected against non-alcoholic fatty liver disease (NAFLD), suggesting Them1 as a therapeutic target. MethodsA high-throughput small molecule screen was performed to identify promising inhibitors targeting the fatty acyl-CoA thioesterase activity of purified recombinant Them1.Counter screening was used to determine specificity for Them1 relative to other acyl-CoA thioesterase isoforms. Inhibitor binding and enzyme inhibition were quantified by biophysical and biochemical approaches, respectively. Following structure-based optimization, lead compounds were tested in cell culture. ResultsTwo lead allosteric inhibitors were identified that selectively inhibited Them1 by binding the START domain. In mouse brown adipocytes, these inhibitors promoted fatty acid oxidation, as evidenced by increased oxygen consumption rates. In mouse hepatocytes, they promoted fatty acid oxidation, but also reduced glucose production. ConclusionThem1 inhibitors could prove attractive for the pharmacologic management of NAFLD.

Acute Endoplasmic Reticulum Stress Suppresses Hepatic Gluconeogenesis by Stimulating MAPK Phosphatase 3 Degradation.

Drug-induced liver injury (DILI) is a widespread and harmful disease, and is closely linked to acute endoplasmic reticulum (ER) stress. Previous reports have shown that acute ER stress can suppress hepatic gluconeogenesis and even leads to hypoglycemia. However, the mechanism is still unclear. MAPK phosphatase 3 (MKP-3) is a positive regulator for gluconeogenesis. Thus, this study was conducted to investigate the role of MKP-3 in the suppression of gluconeogenesis by acute ER stress, as well as the regulatory role of acute ER stress on the expression of MKP-3. Results showed that acute ER stress induced by tunicamycin significantly suppressed gluconeogenesis in both hepatocytes and mouse liver, reduced glucose production level in hepatocytes, and decreased fasting blood glucose level in mice. Additionally, the protein level of MKP-3 was reduced by acute ER stress in both hepatocytes and mouse liver. Mkp-3 deficiency eliminated the inhibitory effect of acute ER stress on gluconeogenesis in hepatocytes. Moreover, the reduction effect of acute ER stress on blood glucose level and hepatic glucose 6-phosphatase (G6pc) expression was not observed in the liver-specific Mkp-3 knockout mice. Furthermore, activation of protein kinase R-like ER kinase (PERK) decreased the MKP-3 protein level, while inactivation of PERK abolished the reduction effect of acute ER stress on the MKP-3 protein level in hepatocytes. Taken together, our study suggested that acute ER stress could suppress hepatic gluconeogenesis by stimulating MKP-3 degradation via PERK, at least partially. Thus, MKP-3 might be a therapeutic target for DILI-related hypoglycemia.

FRI636 Sleep Architecture In Diabetic Patients With Sleep Apnea On Metformin

Abstract Disclosure: M. Varma: None. M. Eghbali: None. D. Hung: None. A. Sahai: None. Background: Metformin, commonly used medication to treat Type II Diabetes Mellitus (DM) improves insulin sensitivity, reduces glucose production in liver and absorption by intestines. Type II DM patients often have higher BMI with increased incidence of sleep apnea. Metformin consuming patients sometimes report insomnia. Blood glucose levels affect sleep duration; therefore Metformin-related changes in blood glucose levels may affect sleep. Metformin prescriptions grew from 40 million in 2004 to 90 million in 2020. This has improved long term vascular complications outcomes in diabetics. Coincidentally the number of patients using sleeping aids has increased. Melatonin sales have doubled since 2004, approximating 821 million USD in sales in 2020. With diabetes and Metformin each causing significant changes in sleep, we aimed to examine sleep architecture in known diabetic patients on Metformin presenting with excessive daytime sleepiness and fatigue. Hypothesis: We hypothesize that Metformin affects sleep and influences sleep architecture in diabetic patients. Methods: Sleep architecture in 29 Type II DM patients taking Metformin, with symptoms of excessive daytime sleepiness, snoring, and fatigue was examined. Patients underwent overnight polysomnography which included six channel EEG, Electrooculogram, Electromyogram EKG, and pulse oximetry, respiratory and flow monitoring in a sleep lab. Sleep staging done using AASM guidelines. Data on age, gender, BMI, medications and sleep stages N1, N2, N3 and REM was collected. Data analyzed and shown as mean + SD, t test p<0.05 significant. Results: All patients had OSA diagnoses per AASM guidelines. The average age of patients with DM and OSA on Metformin therapy was 63 years, average BMI was 36. AASM stage distribution was N1 2.69 % + 0.02, N2 59.31% + 0.15, N3 12.22 % + 0.09, (Normal 25%) with 5.71% +0.06 REM sleep (normal 25%). All stages of sleep were reduced with significant reduction in deep sleep (N3) and REM sleep. Conclusion: Diabetic patients on Metformin had alterations in sleep architecture with significantly reduced restorative phases of deep and REM sleep. Sleep apnea reduces N3 and REM sleep, but diabetic pts had a more significant decrease. Although Metformin improves long term outcomes in diabetes associated complications, it alters sleep patterns. Altered sleep patterns further modify insulin release and over prolonged periods worsen glycemic control. Often patients on Metformin need additional medication like insulin for metabolic control. In part the progression of insulin resistance can be from altered sleep. Better understanding the effects of Metformin on sleep is needed to prevent long-term deteriorating effects on sleep while maintaining effective metabolic control. Presentation: Friday, June 16, 2023

Analysis of multi-disease targeting effect of phytochemicals by AMPK stimulation– diabetes: A computational approach

Diabetes is a silent killer and a metabolic syndrome characterized by hyperglycemia that has been exponentially increasing in recent years. There is a need to develop therapeutic agents to control hyperglycemia and its secondary complications as well as protect and revive beta cells in diabetic patients. The target for first-line diabetes treatment is the adenosine monophosphate protein kinase (AMPK), which participates in cellular energy metabolism through phosphorylation of metabolic enzymes and transcription regulators. This study examined the drug-related properties as well as lead preparation of Catharanthus roseus alkaloids and testing molecular interaction at the AMPK targets to confirm their anti-diabetic effect. A control drug metformin and a library of 85 molecules of C. roseus alkaloids were crossed with the ADMET test, followed by the investigation of molecular interaction tested on AMPK1 and AMPK2 targets through an in silico docking process. Vindolinine (CID: 24148538), vindoline (CID: 425978), (+)-vindorosine (CID: 261578), Cr-1 (CID: 5315746), and Cr-2 (CID: 59908094) had passed the ADMET test. Molecular interaction of the tested C. roseus alkaloids on AMPK1 and AMPK2 targets had potential energy that varied from −7.4 to −5.3 kcal/mol, whereas binding energies of −4.0 kcal/mol for AMPK1-metformin interaction and −4.2 kcal/mol for AMPK2-metformin interaction were observed. The tested C. roseus alkaloids were shown to be more potent activators of AMPK than the control drug. All five biomolecules of C. roseus acted as modulators that have the potential to stimulate AMPK, reduce glucose production, and increase glucose utilization in hepatocytes. In addition, they diminished insulin resistance and secondary complications of diabetes by inhibiting acetyl-CoA carboxylase, regulating cholesterol levels and macrophage, and reviving beta cells in Type 2 diabetes. These results provided the foundation for developing new multi-disease-targeting drugs that can treat diabetes, obesity, cardiovascular disease, cancer, and other diseases by the stimulation of AMPK1 and AMPK2 targets.

Distinct physiological characteristics and altered glucagon signaling in GHRH knockout mice: Implications for longevity.

Our previous research has demonstrated that mice lacking functional growth hormone-releasing hormone (GHRH) exhibit distinct physiological characteristics, including an extended lifespan, a preference for lipid utilization during rest, mild hypoglycemia, and heightened insulin sensitivity. They also show a further increase in lifespan when subjected to caloric restriction. These findings suggest a unique response to fasting, which motivated our current study on the response to glucagon, a key hormone released from the pancreas during fasting that regulates glucose levels, energy expenditure, and metabolism. Our study investigated the effects of an acute glucagon challenge on female GHRH knockout mice and revealed that they exhibit reduced glucose production, likely due to suppressed gluconeogenesis. However, these mice showed an increase in energy expenditure. We also observed alterations in pancreatic islet architecture, with smaller islets and a reduction of insulin-producing beta cells but no changes in glucagon-producing alpha cells. Additionally, the analysis of hepatic glucagon signaling showed a decrease in glucagon receptor expression and phosphorylated CREB. In conclusion, our findings suggest that the unique metabolic phenotype observed in these long-lived mice may be partly explained by changes in glucagon signaling. Further exploration of this pathway may lead to new insights into the regulation of longevity in mammals.

HM-chromanone isolated from Portulaca oleracea L. alleviates insulin resistance and inhibits gluconeogenesis by regulating palmitate-induced activation of ROS/JNK in HepG2 cells.

Oxidative stress is a major cause of hepatic insulin resistance. This study investigated whether (E)-5-hydroxy-7-methoxy-3-(2-hydroxybenzyl)-4-chromanone (HM-chromanone), a homoisoflavonoid compound isolated from Portulaca oleracea L., alleviates insulin resistance and inhibits gluconeogenesis by reducing palmitate (PA)-induced reactive oxygen species (ROS)/c-Jun NH2-terminal kinase (JNK) activation in HepG2 cells. PA treatment (0.5mM) for 16h resulted in the highest production of ROS and induced insulin resistance in HepG2 cells. HM-chromanone, like N-acetyl-1-cysteine, significantly decreased PA-induced ROS production in the cells. HM-chromanone also significantly inhibited PA-induced JNK activation, showing a significant reduction in tumor necrosis factor and interleukin expression levels. Thus, HM-chromanone decreased the phosphorylation of Ser307 in insulin receptor substrate 1, while increasing phosphorylation of serine-threonine kinase (AKT), thereby restoring the insulin signaling pathway impaired by PA. HM-chromanone also significantly increased the phosphorylation of forkhead box protein O, thereby inhibiting the expression of gluconeogenic enzymes and reducing glucose production in PA-treated HepG2 cells. HM-chromanone also increased glycogen synthesis by phosphorylating glycogen synthase kinase-3β. Therefore, HM-chromanone may alleviate insulin resistance and inhibit gluconeogenesis by regulating PA-induced ROS/JNK activation in HepG2 cells.

Role of metformin in the management of type 2 diabetes: recent advances.

Metformin is one of the oldest antidiabetic medications, commonly used in the management of type 2 diabetes. Its mechanism of action is based on reducing glucose production in the liver, decreasing insulin resistance, and increasing insulin sensitivity. The drug has been studied extensively and has been shown to be effective in lowering blood glucose levels without increasing the risk of hypoglycemia. It has been used for the treatment of obesity, gestational diabetes, and polycystic ovary syndrome. According to current guidelines, metformin can be used as the first‑line agent in the management of diabetes; however, in individuals with type 2 diabetes who would benefit from cardio‑renal protection, newer agents, such as sodium‑glucose cotransporter‑2 inhibitors and glucagon‑like peptide‑1 receptor agonists, are favored as the first‑line therapy. The novel classes of antidiabetic medications have demonstrated significant positive effects on glycemia with added benefits in patients with obesity, renal disease, heart failure, and cardiovascular disease. The emergence of these more effective agents has significantly altered the way diabetes is managed, thus prompting re‑evaluation of metformin as the initial therapy for all patients with diabetes.

A caveolin-1 dependent glucose-6-phosphatase trafficking contributes to hepatic glucose production

ObjectiveDeregulation of hepatic glucose production is a key driver in the pathogenesis of diabetes, but its short-term regulation is incompletely deciphered. According to textbooks, glucose is produced in the endoplasmic reticulum by glucose-6-phosphatase (G6Pase) and then exported in the blood by the glucose transporter GLUT2. However, in the absence of GLUT2, glucose can be produced by a cholesterol-dependent vesicular pathway, which remains to be deciphered. Interestingly, a similar mechanism relying on vesicle trafficking controls short-term G6Pase activity. We thus investigated whether Caveolin-1 (Cav1), a master regulator of cholesterol trafficking, might be the mechanistic link between glucose production by G6Pase in the ER and glucose export through a vesicular pathway. MethodsGlucose production from fasted mice lacking Cav1, GLUT2 or both proteins was measured in vitro in primary culture of hepatocytes and in vivo by pyruvate tolerance tests. The cellular localization of Cav1 and the catalytic unit of glucose-6-phosphatase (G6PC1) were studied by western blotting from purified membranes, immunofluorescence on primary hepatocytes and fixed liver sections and by in vivo imaging of chimeric constructs overexpressed in cell lines. G6PC1 trafficking to the plasma membrane was inhibited by a broad inhibitor of vesicular pathways or by an anchoring system retaining G6PC1 specifically to the ER membrane. ResultsHepatocyte glucose production is reduced at the step catalyzed by G6Pase in the absence of Cav1. In the absence of both GLUT2 and Cav1, gluconeogenesis is nearly abolished, indicating that these pathways can be considered as the two major pathways of de novo glucose production. Mechanistically, Cav1 colocalizes but does not interact with G6PC1 and controls its localization in the Golgi complex and at the plasma membrane. The localization of G6PC1 at the plasma membrane is correlated to glucose production. Accordingly, retaining G6PC1 in the ER reduces glucose production by hepatic cells. ConclusionsOur data evidence a pathway of glucose production that relies on Cav1-dependent trafficking of G6PC1 to the plasma membrane. This reveals a new cellular regulation of G6Pase activity that contributes to hepatic glucose production and glucose homeostasis.

The Potential Therapeutic Role of Metformin in Diabetic and Non-Diabetic Bone Impairment.

Metformin is a widely-used anti-diabetic drug in patients with type 2 diabetic mellitus (T2DM) due to its safety and efficacy in clinical. The classic effect of metformin on lowering blood glucose levels is to inhibit liver gluconeogenesis that reduces glucose production as well as increases peripheral glucose utilization. However, the factors such as hyperglycemia, insulin deficiency, reduced serum levels of insulin-like growth factor-1 (IGF-1) and osteocalcin, accumulation of advanced glycation end products (AGEs), especially in collagen, microangiopathy, and inflammation reduced bone quality in diabetic patients. However, hyperglycemia, insulin deficiency, reduced levels of insulin-like growth factor-1 (IGF-1) and osteocalcin in serum, accumulation of advanced glycation end products (AGEs) in collagen, microangiopathy, and inflammation, reduce bone quality in diabetic patients. Furthermore, the imbalance of AGE/RAGE results in bone fragility via attenuating osteogenesis. Thus, adequate glycemic control by medical intervention is necessary to prevent bone tissue alterations in diabetic patients. Metformin mainly activates adenosine 5′ -monophosphate-activated protein kinase (AMPK), and inhibits mitochondrial respiratory chain complex I in bone metabolism. In addition, metformin increases the expression of transcription factor runt-related transcription factor2 (RUNX2) and Sirtuin protein to regulate related gene expression in bone formation. Until now, there are a lot of preclinical or clinical findings on the application of metformin to promote bone repair. Taken together, metformin is considered as a potential medication for adjuvant therapy in bone metabolic disorders further to its antidiabetic effect. Taken together, as a conventional hypoglycemia drug with multifaceted effects, metformin has been considered a potential adjuvant drug for the treatment of bone metabolic disorders.

2-OR: Exosomes from Adipose Tissue Macrophages Can Mediate Insulin-Sensitizing Effects of Rosiglitazone

Background: The beneficial metabolic effects of the PPARγ agonist rosiglitazone (Rosi) are associated with anti-inflammatory changes in adipose tissue macrophages (ATMs) . One study aim was to characterize the in vivo Rosi-induced phenotypic switch of ATMs using a variety of macrophage markers, including the lipid-associated macrophage markers CD9 and Trem2. As a second aim, since ATM-derived exosomes can exert insulin-sensitizing or desensitizing effects dependent on ATM cell context, we assessed the effects of ATM exosomes from Rosi-treated obese mice on in vitro insulin actions. Research Design and Method: ATMs were isolated from 4 months HFD/obese mice treated for the last month with Rosi (60 mg/kg HFD) compared to HFD or chow-fed controls. Among CD11b+F4/80+ or CD64+ macrophages, we identified pro-inflammatory (“M1-like” CD11c+ and/or CD9+) , anti-inflammatory (“M2-like” CD11c-CD206+) and lipid-associated (CD9+ and/or Trem2+) ATMs by flow cytometry. Bone marrow-derived macrophages (BMDMs) were treated in vitro with µM Rosi for 24h. 3T3-L1 adipocytes, L6 myotubes, and primary hepatocytes were cultured 24h with exosomes isolated from ATMs of Rosi treated obese mice or in vitro Rosi treated BMDMs and then assessed for insulin sensitivity. Results: Rosi treatment reduced adipose tissue inflammation, as seen by reduced numbers of pro-inflammatory (“M1-like”) ATMs and increased the Trem2 signature in “M2-like” ATMs. Importantly, Rosi directly induced Trem2 expression in vitro in BMDMs. Additionally, exosomes isolated from Rosi-treated obese mice or M1 BMDMs increased glucose uptake and insulin signalling (pAKT) in adipocytes and myotubes and reduced glucose production in hepatocytes compared to control exosomes. Conclusion: Our data indicate that Trem2 is a PPARγ target gene. Since exosomes from Rosi treated ATMs or BMDMs enhance cellular insulin action, this could provide a new explanation for the well-known insulin-sensitizing effects of PPARγ agonists. Disclosure T.V.Rohm: None. F.C.G.Reis: None. R.Isaac: None. M.Paszek: None. G.Bandyopadhyay: None. J.M.Olefsky: None. Funding Swiss National Science Foundation (SNF) Early Postdoc.Mobility grant (to T.R.) .

215-LB: Silencing of Fructose 1,6-Bisphosphatase (FBP1) in Liver Improves Glucose Homeostasis in Insulin-Resistant Rodent and Human Models

Insulin resistant individuals display elevated fasting and post-prandial glucose levels which are mainly driven by inadequate inhibition of gluconeogenesis (GNG) and are rarely normalized. The aim of this study was to investigate whether direct inhibition of GNG could be a new therapeutical approach to improve glucose homeostasis using in vitro and in vivo models of insulin resistance. Fructose 1,6-bisphosphatase (FBP1) is key in controlling GNG in liver and kidney and loss of function patients display hypoglycaemia episodes and lactate acidosis. Systemic FBP1 inhibition using small molecules has shown to improve glucose homeostasis. To assess the clinical efficacy and safety potential of silencing FBP1 selectively in the liver we dosed insulin resistant DIO rats with a hepatocyte specific GalXC-FBP1 siRNA entity. GalXC-FBP1 siRNA markedly reduced FBP1 mRNA level in the liver by over 90%. This was associated with a complete lack of glucose excursion following a pyruvate challenge indicating inhibition of GNG. Blood glucose level decreased similarly in rats treated with GalXC-FBP1 siRNA or vehicle during an insulin challenge or a prolonged fast suggesting that hepatic FBP1 silencing is not inducing hypoglycaemia. Insulin sensitivity and hyperinsulinemia were improved. Plasma lactate and liver enzymes were not elevated, but a significant 2-fold increase in liver triglycerides was observed in the GalXC-FBP1 siRNA group. Using human hepatocytes in a Liver-on-Chip in vitro model FBP1 silencing reduced glucose production by 30% supporting the relevance of this approach in humans. Collectively these data suggest that liver specific FBP1 silencing has the potential to improve insulin sensitivity in DIO rats without inducing hypoglycaemia but may be associated with a risk of liver steatosis overtime. This concept highlights the difficulty of blocking liver GNG without re-directing the metabolic intermediates fluxes toward triglycerides accumulation in liver. Disclosure C. Fledelius: Employee; Novo Nordisk A/S. D. Demozay: Employee; Novo Nordisk A/S. H. Iversen: None. R. S. Ingvorsen: None. L. B. Eriksen: None. A. Blois: Employee; Novo Nordisk. Y. Montauban: None. R. Rijnbrand: Employee; Novo Nordisk. W. Han: None. J. F. Jeppesen: Employee; Novo Nordisk A/S.

Catestatin induces glycogenesis by stimulating the phosphoinositide 3-kinase-AKT pathway.

Defects in hepatic glycogen synthesis contribute to post-prandial hyperglycaemia in type 2 diabetic patients. Chromogranin A (CgA) peptide Catestatin (CST: hCgA352-372 ) improves glucose tolerance in insulin-resistant mice. Here, we seek to determine whether CST induces hepatic glycogen synthesis. We determined liver glycogen, glucose-6-phosphate (G6P), uridine diphosphate glucose (UDPG) and glycogen synthase (GYS2) activities; plasma insulin, glucagon, noradrenaline and adrenaline levels in wild-type (WT) as well as in CST knockout (CST-KO) mice; glycogen synthesis and glycogenolysis in primary hepatocytes. We also analysed phosphorylation signals of insulin receptor (IR), insulin receptor substrate-1 (IRS-1), phosphatidylinositol-dependent kinase-1 (PDK-1), GYS2, glycogen synthase kinase-3β (GSK-3β), AKT (a kinase in AKR mouse that produces Thymoma)/PKB (protein kinase B) and mammalian/mechanistic target of rapamycin (mTOR) by immunoblotting. CST stimulated glycogen accumulation in fed and fasted liver and in primary hepatocytes. CST reduced plasma noradrenaline and adrenaline levels. CST also directly stimulated glycogenesis and inhibited noradrenaline and adrenaline-induced glycogenolysis in hepatocytes. In addition, CST elevated the levels of UDPG and increased GYS2 activity. CST-KO mice had decreased liver glycogen that was restored by treatment with CST, reinforcing the crucial role of CST in hepatic glycogenesis. CST improved insulin signals downstream of IR and IRS-1 by enhancing phospho-AKT signals through the stimulation of PDK-1 and mTORC2 (mTOR Complex 2, rapamycin-insensitive complex) activities. CST directly promotes the glycogenic pathway by (a) reducing glucose production, (b) increasing glycogen synthesis from UDPG, (c) reducing glycogenolysis and (d) enhancing downstream insulin signalling.

Enhanced alleviation of insulin resistance via the IRS-1/Akt/FOXO1 pathway by combining quercetin and EGCG and involving miR-27a-3p and miR-96–5p

Quercetin and EGCG exhibit anti-diabetic and anti-obesity activities, however, their interactive effects in anti-diabetic/anti-obesity actions and underlying mechanisms remain unclear. This study aimed to fill these knowledge gaps. Quercetin, EGCG or their combination attenuated insulin resistance and decreased hepatic gluconeogenesis in high-fat-high-fructose diet (HFFD)-fed C57BL/6 mice and in palmitic acid (PA)-treated HepG2 cells. In mice, supplementation with quercetin (0.05%w/w), EGCG (0.05%w/w) and their combination (quercetin 0.05%+EGCG 0.05%w/w) reduced weight gain and fasting blood glucose and improved serum biochemical parameters. Compare with quercetin/EGCG alone, the quercetin-EGCG combination reduced gluconeogenesis to a greater extent via IRS-1/Akt/FOXO1-mediated down-regulation of downstream PEPCK and G-6-pase. In HepG2 cells, the quercetin (5 μM)-EGCG (5 μM) co-treatment exerted greater suppression on PA-induced changes in glucose and glycogen contents and hexokinase and G-6-pase activities than quercetin/EGCG alone (each 10 μM). The quercetin-EGCG co-treatment reduced glucose production through targeting FOXO1 and inhibiting the transcription of gluconeogenic enzymes. MiR-27a-3p and miR-96–5p regulated directly FOXO1 expression and function, and co-inhibition of miR-27a-3p and miR-96–5p weakened greatly the protective effect of quercetin-EGCG combination. This is the first report on the contributions of miR-27a-3p and miR-96–5p to the synergistic and protective effect of the quercetin-EGCG co-treatment against PA-induced insulin resistance through inhibiting FOXO1 expression.