Targeting AMP-activated protein kinase as a novel therapeutic approach for the treatment of metabolic disorders. Diabetes Metab. 2007;33:395-402. [PMID: 17997341 DOI: 10.1016/j.diabet.2007.10.004]

The interaction between the Circadian Locomotor Output Cycles Kaput and Melanocortin-4-receptor gene variants on obesity and parameters related to obesity

INTRODUCTION

Obesity is a multifactorial disease caused by an interaction between genetic, environmental and behavioral factors. Polymorphisms of the two genes Circadian Locomotor Output Cycles Kaput (CLOCK) rs1801260 and Melanocortin-4-receptor (MC4R) rs17782313, are associated with obesity. Knowledge is limited on the interaction between CLOCK, MC4R and obesity. The aim was to explore the interactions between the CLOCK and MC4R gene variants on markers related to obesity.

METHODS

There were 423 subjects with information on two genetic variants of two genes (CLOCK and MC4R). Their interaction was evaluated with: chronotype, sleeping duration, emotional eating, food timing, stress, dietary intake, appetite, physical activity (assessed by questionnaires), anthropometric measures of obesity (assessed by physical measurements), and also hormonal factors (assessed by ELISA). Generalized Linear Models were applied.

RESULTS

Our results revealed that significant differences were observed between the genotypes of CLOCK rs1801260 for weight, Body Mass Index (BMI), Glucagon-like peptide-1 (GLP-1), cortisol, energy, fat, sleep duration, chronotype, appetite, depression, stress, emotional eating, physical activity, breakfast, lunch, and dinner time (p˂0.05). Also, significant differences were observed between the genotypes of MC4R rs17782313 for weight, BMI, Waist Circumference (WC), Waist to Hip Ratio (WHR), ghrelin, energy, carbohydrate, fat, appetite, depression, stress, breakfast time, and emotional eating (p˂0.05). Our findings also showed significant interactions between the CLOCK (CC)∗MC4R (CT) genotypes for higher appetite, stress and CLOCK (CT)∗ MC4R (CC) genotypes for higher fat and energy intake and CLOCK (CC)∗MC4R (CC) genotypes for higher weight, BMI, energy and fat intake, appetite, emotional eating, stress, ghrelin, cortisol and lower sleep duration and GLP-1 (p˂ 0.05).

CONCLUSION

Due to the non-significance of the interaction in CLOCK (CT)∗ MC4R (CT) genotypes, it seems that the presence of a healthy arm in the CLOCK and MC4R polymorphism is necessary for the proper function of the genes. Thus, these results highlight that gene variants and their interaction should be considered in obesity assessment.

Administration of AICAR, an AMPK Activator, Prevents and Reverses Diabetic Polyneuropathy (DPN) by Regulating Mitophagy

Diabetic peripheral neuropathy (DPN) is a common complication of diabetes in both Type 1 (T1D) and Type 2 (T2D). While there are no specific medications to prevent or treat DPN, certain strategies can help halt its progression. In T1D, maintaining tight glycemic control through insulin therapy can effectively prevent or delay the onset of DPN. However, in T2D, overall glucose control may only have a moderate impact on DPN, although exercise is clearly beneficial. Unfortunately, optimal exercise may not be feasible for many patients with DPN because of neuropathic foot pain and poor balance. Exercise has several favorable effects on health parameters, including body weight, glycemic control, lipid profile, and blood pressure. We investigated the impact of an exercise mimetic, 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR), on DPN. AICAR treatment prevented or reversed experimental DPN in mouse models of both T2D and T1D. AICAR in high-fat diet (HFD-fed) mice increased the phosphorylation of AMPK in DRG neuronal extracts, and the ratio of phosphorylated AMPK to total AMPK increased by 3-fold (HFD vs. HFD+AICAR; p < 0.001). Phospho AMP increased the levels of dynamin-related protein 1 (DRP1, a mitochondrial fission marker), increased phosphorylated autophagy activating kinase 1 (ULK1) at Serine-555, and increased microtubule-associated protein light chain 3-II (LC3-II, a marker for autophagosome assembly) by 2-fold. Mitochondria isolated from DRG neurons of HFD-fed had a decrease in ADP-stimulated state 3 respiration (120 ± 20 nmol O2/min in HFD vs. 220 ± 20 nmol O2/min in control diet (CD); p < 0.001. Mitochondria isolated from HFD+AICAR-treated mice had increased state 3 respiration (240 ± 30 nmol O2/min in HFD+AICAR). However, AICAR's protection in DPN in T2D mice was also mediated by its effects on insulin sensitivity, glucose metabolism, and lipid metabolism. Drugs that enhance AMPK phosphorylation may be beneficial in the treatment of DPN.

Ferulic acid improves palmitate-induced insulin resistance by regulating IRS-1/Akt and AMPK pathways in L6 skeletal muscle cells

Objective

Increased plasma-free fatty acid (FFA) induced by obesity can trigger insulin resistance and it is a significantly dangerous constituent in the progression of diabetes. Although ferulic acid has various physiological functions, no studies have examined ferulic acid's effects on insulin-resistant muscle cells. This study investigated the effect of ferulic acid on improving palmitic acid-induced insulin resistance in L6 skeletal muscle cells.

Methods

Palmitic acid induces insulin resistance by inhibiting the phosphorylation of IRS-1tyr and stimulating the phosphorylation of IRS-1ser in diabetes. Thus, palmitic acid (0.75 mM) was used as an insulin resistance inducer and ferulic acid was treated at various concentrations (2, 5, 10, and 20 uM) in L6 skeletal muscle cells.

Results

Palmitic acid significantly reduced the cell viability of L6 skeletal muscle cells, whereas ferulic acid treatment significantly increased cell viability in a concentration-dependent manner. Palmitic acid significantly reduced glucose uptake due to insulin resistance in the muscle cells; however, ferulic acid treatment remarkably increased glucose uptake. Ferulic acid promoted the phosphorylation of IRS-1tyr that palmitic acid inhibited, while also suppressing the palmitic acid-induced phosphorylation of IRS-1ser. Ferulic acid activated PI3K and then stimulated the phosphorylation of Akt, which increased PM-GLUT4 expression, thereby stimulating glucose uptake into insulin-resistant muscle cells. Ferulic acid also increased glycogen synthesis by phosphorylating GSK3β via the Akt pathway. Additionally, ferulic acid significantly promoted phosphorylation of AMPK, enhancing PM-GLUT4 levels and glucose uptake.

Conclusions

These results suggest that ferulic acid may improve palmitate-induced insulin resistance by regulating IRS-1/ Akt and the AMPK pathway in L6 skeletal muscle cells.

Ramadan fasting model modulates biomarkers of longevity and metabolism in male obese and non-obese rats

The health advantages of Ramadan fasting, a time-restricted eating from dawn to dusk, have garnered attention. Nevertheless, prior observational studies have found inconsistent findings because of challenges regulating variables such as sleep patterns, dietary habits, and physical activity. This study sought to investigate the impact of the Ramadan fasting model (RFM) on longevity and metabolic biomarkers in obese and non-obese rats. For 12 weeks, 48 male Wistar albino rats were separated into two groups and fed either a standard or a high-fat diet (HFD). During the final four weeks, rats in each group were separated into four subgroups to investigate the effect of RFM with/without training (on Treadmill) or glucose administration on the biomarkers of interest. The HFD groups subjected to RFM had significantly lower Insulin-like growth factor 1 (IGF-1) and mechanistic target of rapamycin (mTOR) serum, whereas AMPK, anti-inflammatory, and antioxidative stress serum levels were significantly higher. All groups reported decreased serum levels of Interleukin-6 (IL-6) and Tumor Necrosis Factor-alpha (TNF-α) compared to the HFD control group. Furthermore, the Real-Time Quantitative Polymerase Chain Reaction (RT-qPCR) results indicated a significant elevation in the TP53 gene expression in groups subjected to RFM. The data indicate that RFM can improve longevity and metabolic biomarkers and reduce pro-inflammation and oxidative stress. Also, RFM improves anti-inflammatory and antioxidant markers in HFD-induced obese rats.

Decreasing Intracellular Entropy by Increasing Mitochondrial Efficiency and Reducing ROS Formation-The Effect on the Ageing Process and Age-Related Damage

A hypothesis is presented to explain how the ageing process might be influenced by optimizing mitochondrial efficiency to reduce intracellular entropy. Research-based quantifications of entropy are scarce. Non-equilibrium metabolic reactions and compartmentalization were found to contribute most to lowering entropy in the cells. Like the cells, mitochondria are thermodynamically open systems exchanging matter and energy with their surroundings-the rest of the cell. Based on the calculations from cancer cells, glycolysis was reported to produce less entropy than mitochondrial oxidative phosphorylation. However, these estimations depended on the CO2 concentration so that at slightly increased CO2, it was oxidative phosphorylation that produced less entropy. Also, the thermodynamic efficiency of mitochondrial respiratory complexes varies depending on the respiratory state and oxidant/antioxidant balance. Therefore, in spite of long-standing theoretical and practical efforts, more measurements, also in isolated mitochondria, with intact and suboptimal respiration, are needed to resolve the issue. Entropy increases in ageing while mitochondrial efficiency of energy conversion, quality control, and turnover mechanisms deteriorate. Optimally functioning mitochondria are necessary to meet energy demands for cellular defence and repair processes to attenuate ageing. The intuitive approach of simply supplying more metabolic fuels (more nutrients) often has the opposite effect, namely a decrease in energy production in the case of nutrient overload. Excessive nutrient intake and obesity accelerate ageing, while calorie restriction without malnutrition can prolong life. Balanced nutrient intake adapted to needs/activity-based high ATP requirement increases mitochondrial respiratory efficiency and leads to multiple alterations in gene expression and metabolic adaptations. Therefore, rather than overfeeding, it is necessary to fine-tune energy production by optimizing mitochondrial function and reducing oxidative stress; the evidence is discussed in this paper.

Platycodin D Ameliorates Type 2 Diabetes-Induced Myocardial Injury by Activating the AMPK Signaling Pathway

The current study aimed to assess the effectiveness of pharmacological intervention with Platycodin D (PD), a critically active compound isolated from the roots of Platycodon grandiflorum, in mitigating cardiotoxicity in a murine model of type 2 diabetes-induced cardiac injury and in H9c2 cells in vitro. Following oral administration for 4 weeks, PD (2.5 mg/kg) significantly suppressed the elevation of fasting blood glucose (FBG) levels, improved dyslipidemia, and effectively inhibited the rise of the cardiac injury markers creatine kinase isoenzyme MB (CK-MB) and cardiac troponin T (cTnT). PD treatment could ameliorate energy metabolism disorders induced by impaired glucose uptake by activating AMPK protein expression in the DCM mouse model, thereby promoting the GLUT4 transporter and further activating autophagy-related proteins. Furthermore, in vitro experiments demonstrated that PD exerted a concentration-dependent increase in cell viability while also inhibiting palmitic acid and glucose (HG-PA)-stimulated H9c2 cytotoxicity and activating AMPK protein expression. Notably, the AMPK activator AICAR (1 mM) was observed to upregulate the expression of AMPK in H9c2 cells after high-glucose and -fat exposure. Meanwhile, we used AMPK inhibitor Compound C (20 μM) to investigate the effect of PD activation of AMPK on cells. In addition, the molecular docking approach was employed to dock PD with AMPK, revealing a binding energy of -8.2 kcal/mol and indicating a tight interaction between the components and the target. PD could reduce the expression of autophagy-related protein p62, reduce the accumulation of autophagy products, promote the flow of autophagy, and improve myocardial cell injury. In conclusion, it has been demonstrated that PD effectively inhibits cardiac injury-induced type 2 diabetes in mice and enhances energy metabolism in HG-PA-stimulated H9c2 cells by activating the AMPK signaling pathway. These findings collectively unveil the potential cardioprotective effects of PD via modulation of the AMPK signaling pathway.

Adiponectin Resistance in Obesity: Adiponectin Leptin/Insulin Interaction

The adiponectin (APN) levels in obesity are negatively correlated with chronic subclinical inflammation markers. The hypertrophic adipocytes cause obesity-linked insulin resistance and metabolic syndrome. Furthermore, macrophage polarization is a key determinant regulating adiponectin receptor (AdipoR1/R2) expression and differential adiponectin-mediated macrophage inflammatory responses in obese individuals. In addition to decrease in adiponectin concentrations, the decline in AdipoR1/R2 messenger ribonucleic acid (mRNA) expression leads to a decrement in adiponectin binding to cell membrane, and this turns into attenuation in the adiponectin effects. This is defined as APN resistance, and it is linked with insulin resistance in high-fat diet-fed subjects. The insulin-resistant group has a significantly higher leptin-to-APN ratio. The leptin-to-APN ratio is more than twofold higher in obese individuals. An increase in expression of AdipoRs restores insulin sensitivity and β-oxidation of fatty acids via triggering intracellular signal cascades. The ratio of high molecular weight to total APN is defined as the APN sensitivity index (ASI). This index is correlated to insulin sensitivity. Homeostasis model of assessment (HOMA)-APN and HOMA-estimated insulin resistance (HOMA-IR) are the most suitable methods to estimate the metabolic risk in metabolic syndrome. While morbidly obese patients display a significantly higher plasma leptin and soluble (s)E-selectin concentrations, leptin-to-APN ratio, there is a significant negative correlation between leptin-to-APN ratio and sP-selectin in obese patients. When comparing the metabolic dysregulated obese group with the metabolically healthy obese group, postprandial triglyceride clearance, insulin resistance, and leptin resistance are significantly delayed following the oral fat tolerance test in the first group. A neuropeptide, Spexin (SPX), is positively correlated with the quantitative insulin sensitivity check index (QUICKI) and APN. APN resistance together with insulin resistance forms a vicious cycle. Despite normal or high APN levels, an impaired post-receptor signaling due to adaptor protein-containing pleckstrin homology domain, phosphotyrosine-binding domain, and leucine zipper motif 1 (APPL1)/APPL2 may alter APN efficiency and activity. However, APPL2 blocks adiponectin signaling through AdipoR1 and AdipoR2 because of the competitive inhibition of APPL1. APPL1, the intracellular binding partner of AdipoRs, is also an important mediator of adiponectin-dependent insulin sensitization. The elevated adiponectin levels with adiponectin resistance are compensatory responses in the condition of an unusual discordance between insulin resistance and APN unresponsiveness. Hypothalamic recombinant adeno-associated virus (rAAV)-leptin (Lep) gene therapy reduces serum APN levels, and it is a more efficient strategy for long-term weight maintenance.

Integrative approach to uncover antioxidant properties of Bupleuri Radix and its active compounds: Multiscale interactome-level analysis with experimental validation

Acute and chronic liver disease are global problems with high morbidity and mortality. Bupleuri Radix (BR) is an herbal medicine that has been prescribed empirically in traditional Asian medicine to modulate liver metabolism. However, its active compounds and therapeutic mechanisms remain unclear. Here, we integrated a network-based approach and experimental validation to elucidate BR's therapeutic potential in treating oxidative liver injury. Our approach incorporated data collection and network construction utilizing bioinformatics tools, and identified active compounds and key mechanisms based on the multiscale interactome. The proposed mechanisms were validated using an in vitro oxidative stress model and an in vivo carbon tetrachloride-induced model. We found that BR ameliorated the oxidative hepatic damage by acting on multiple proteins (STAT3, TNF, and BCL2) and signaling pathways (AMPK and Hippo signaling pathways). Subsequent in vitro experiments confirmed that BR significantly inhibited oxidative stress and mitochondrial damage. We further validated the effect of BR on the AMPK and Hippo-YAP pathways; a key mechanism for the antioxidant properties of BR. We prioritized the active compounds in BR based on a multiscale interactome-based approach, and further experiments revealed that saikosaponin A was a key active compound involved in hepatocyte protection (EC₅₀ = 50 μM), similar to the result using metformin and 5-aminoimidazole-4-carboxamide ribonucleotide. Histochemistry and blood biochemistry established that BR significantly inhibited carbon tetrachloride-induced oxidative tissue damage in mice. Thus, BR can be used to develop novel therapeutics for oxidative liver injury. Moreover, we suggest a novel strategy to prioritize and validate the active compounds and key mechanisms of herbal medicine based on the multiscale interactome.

Alfalfa Xeno-miR168b Target CPT1A to Regulate Milk Fat Synthesis in Bovine Mammary Epithelial Cells

It was shown that microRNAs (miRNAs) play an important role in the synthesis of milk fat; thus, this manuscript evaluated whether exogenous miRNA (xeno-miRNAs) from alfalfa could influence the milk fat content in dairy cows. At first, mtr-miR168b was screened from dairy cow milk and blood. Then, EdU staining, flow cytometry, Oil Red O staining, qRT-PCR, and WB were applied to explore the effect of xeno-miR168b on the proliferation, apoptosis, and lipid metabolism of bovine mammary epithelial cells (BMECs). Finally, in order to clarify the pathway that regulated the lipid metabolism of BMECs using xeno-miR168b, a double-luciferase reporter assay was used to verify the target gene related to milk fat. These results showed that overexpression of xeno-miR168b inhibited cell proliferation but promoted apoptosis, which also decreased the expression of several lipid metabolism genes, including PPARγ, SCD1, C/EBPβ, and SREBP1, significantly inhibited lipid droplet formation, and reduced triglyceride content in BMECs. Furthermore, the targeting relationship between CPT1A and xeno-miR168b was determined and it was confirmed that CPT1A silencing reduced the expression of lipid metabolism genes and inhibited fat accumulation in BMECs. These findings identified xeno-miR168b from alfalfa as a cross-kingdom regulatory element that could influence milk fat content in dairy cows by modulating CPT1A expression.

Characterization of the Impacts of Living at High Altitude in Taif: Oxidative Stress Biomarker Alterations and Immunohistochemical Changes

At high elevations, the human body experiences a number of pathological, physiological, and biochemical changes, all of which have adverse impacts on human health and organ vitality. This study aimed to investigate the alterations in the liver and kidney biomarkers, oxidative stress markers, gene expression, and cellular histology of rats maintained at high altitudes and normal sea level. A total of twenty male Wistar rats at 2 months of age were randomly assigned to two groups. The rats in group A were maintained at normal sea level in Jeddah, whereas rats in group B were maintained in an area in Taif 2600 m above sea level. After 2 months of housing, orbital blood samples were collected for the analysis of significant biochemical indicators of oxidative stress biomarkers of the liver and kidneys. Liver and kidney tissues from both groups were taken to examine the hepatorenal changes occurring at the biochemical, histological, immunohistochemical, and genetic levels. The results revealed substantial increases in the serum levels of liver and kidney biomarkers (GPT, GOT, urea, and creatinine) and decreases in the serum levels of antioxidant biomarkers (SOD, catalase, GSH, and NO). In parallel, the levels of the malondialdehyde (MDA) tissue damage marker and inflammatory cytokines (IL-1β, TNF-α, and IFN-γ) were increased in the high-altitude group compared to the normal sea level group. In addition, there were significant alterations in the oxidative and inflammatory status of rats that lived at high altitude, with considerable upregulation in the expression of hepatic VEGF, type 1 collagen, Cox-2, TNF-α, and iNOS as well as renal EPASI, CMYC, HIF-α, and EGLN-2 genes in the high-altitude group compared with controls housed at normal sea level. In conclusion, living at high altitude induces hepatorenal damage and biochemical and molecular alterations, all of which may serve as critical factors that must be taken into account for organisms living at high altitudes.

Chemotherapy Resistance: Role of Mitochondrial and Autophagic Components

Simple Summary

Chemotherapy resistance is a common occurrence during cancer treatment that cancer researchers are attempting to understand and overcome. Mitochondria are a crucial intracellular signaling core that are becoming important determinants of numerous aspects of cancer genesis and progression, such as metabolic reprogramming, metastatic capability, and chemotherapeutic resistance. Mitophagy, or selective autophagy of mitochondria, can influence both the efficacy of tumor chemotherapy and the degree of drug resistance. Regardless of the fact that mitochondria are well-known for coordinating ATP synthesis from cellular respiration in cellular bioenergetics, little is known its mitophagy regulation in chemoresistance. Recent advancements in mitochondrial research, mitophagy regulatory mechanisms, and their implications for our understanding of chemotherapy resistance are discussed in this review.

Abstract

Cancer chemotherapy resistance is one of the most critical obstacles in cancer therapy. One of the well-known mechanisms of chemotherapy resistance is the change in the mitochondrial death pathways which occur when cells are under stressful situations, such as chemotherapy. Mitophagy, or mitochondrial selective autophagy, is critical for cell quality control because it can efficiently break down, remove, and recycle defective or damaged mitochondria. As cancer cells use mitophagy to rapidly sweep away damaged mitochondria in order to mediate their own drug resistance, it influences the efficacy of tumor chemotherapy as well as the degree of drug resistance. Yet despite the importance of mitochondria and mitophagy in chemotherapy resistance, little is known about the precise mechanisms involved. As a consequence, identifying potential therapeutic targets by analyzing the signal pathways that govern mitophagy has become a vital research goal. In this paper, we review recent advances in mitochondrial research, mitophagy control mechanisms, and their implications for our understanding of chemotherapy resistance.

Therapeutic Potential of Seaweed-Derived Bioactive Compounds for Cardiovascular Disease Treatment

Cardiovascular diseases are closely related to hypertension, type 2 diabetes mellitus, obesity, and hyperlipidemia. Many studies have reported that an unhealthy diet and sedentary lifestyle are critical factors that enhance these diseases. Recently, many bioactive compounds isolated from marine seaweeds have been studied for their benefits in improving human health. In particular, several unique bioactive metabolites such as polyphenols, polysaccharides, peptides, carotene, and sterol are the most effective components responsible for these activities. This review summarizes the current in vitro, in vivo, and clinical studies related to the protective effects of bioactive compounds isolated from seaweeds against cardiovascular disorders, including anti-diabetic, anti-hypertensive, anti-hyperlipidemia, and anti-obesity effects. Therefore, this present review summarizes these concepts and provides a basis for further in-depth research.

Pharmacological Approaches to Attenuate Inflammation and Obesity with Natural Products Formulations by Regulating the Associated Promoting Molecular Signaling Pathways

Obesity is a public health problem characterized by increased body weight due to abnormal adipose tissue expansion. Bioactive compound consumption from the diet or intake of dietary supplements is one of the possible ways to control obesity. Natural products with adipogenesis-regulating potential act as obesity treatments. We evaluated the synergistic antiangiogenesis, antiadipogenic and antilipogenic efficacy of standardized rebaudioside A, sativoside, and theasaponin E1 formulations (RASE1) in vitro in human umbilical vein endothelial cells (HUVECs), 3T3-L1 preadipocytes respectively, and in vivo using a high-fat and carbohydrate diet-induced obesity mouse model. Orlistat was used as a positive control, while untreated cells and animals were normal controls (NCs). Adipose tissue, liver, and blood were analyzed after dissection. Extracted stevia compounds and green tea seed saponin E1 exhibited pronounced antiobesity effects when combined. RASE1 inhibited HUVEC proliferation and tube formation by suppressing VEGFR2, NF-κB, PIK3, and-catenin beta-1 expression levels. RASE1 inhibited 3T3-L1 adipocyte differentiation and lipid accumulation by downregulating adipogenesis- and lipogenesis-promoting genes. RASE1 oral administration reduced mouse body and body fat pad weight and blood cholesterol, TG, ALT, AST, glucose, insulin, and adipokine levels. RASE1 suppressed adipogenic and lipid metabolism gene expression in mouse adipose and liver tissues and enhanced AMP-activated protein kinase levels in liver and adipose tissues and in serum adiponectin. RASE1 suppressed the NF-κB pathway and proinflammatory cytokines IL-10, IL-6, and TNF-α levels in mice which involve inflammation and progression of obesity. The overall results indicate RASE1 is a potential therapeutic formulation and functional food for treating or preventing obesity and inflammation.

Secukinumab and metformin ameliorate dermal fibrosis by decreasing tissue interleukin-17 levels in bleomycin-induced dermal fibrosis

Although the pathogenesis of systemic sclerosis is not exactly known, it is thought that immune activation has prominent roles in pathogenesis. Secukinumab is a monoclonal antibody against interleukin (IL)-17A. Metformin, a widely used antidiabetic medication, has anti-proliferative, immunomodulating and anti-fibrotic activities. The purpose of our study is to determine the therapeutic efficacy of secukinumab and metformin on bleomycin (BLM) induced dermal fibrosis. Fifty Balb/c female mice were divided into 5 groups: (group 1 control, 2 sham, 3 secukinumab, 4 metformin and 5 secukinumab + metformin). The mice in the control group received 100 μL phosphate-buffered saline (PBS), while the mice in other groups received 100 μL (100 μg) BLM in PBS subcutaneously (sc) every day for 4 weeks. In addition, mice in groups 3 and 5 received secukinumab at a dose of 10 mg/kg/wk sc, and mice in the groups 4 and 5 received oral metformin 50 mg/kg/d for 28 days. All groups of mice were sacrificed at the end of the 4th week and tissue samples were taken for analysis. In addition to histopathological analysis, skin tissue messenger RNA (mRNA) expressions of IL-17 and collagen 3A were measured by real-time polymerase chain reaction. Repeated BLM injections had caused dermal fibrosis. In addition, the mRNA expressions of IL-17 and collagen 3A were increased in the BLM group. Secukinumab and metformin ameliorated dermal fibrosis. They decreased dermal thickness and tissue IL-17A and collagen 3A mRNA levels. Secukinumab and metformin exhibit anti-fibrotic effects in the BLM-induced dermal fibrosis.

Lisofylline mitigates cardiac inflammation in a mouse model of obesity through improving insulin secretion and activating cardiac AMPK signaling pathway

Obesity has emerged as a leading cause of death in the last few decades, mainly due to associated cardiovascular diseases. Obesity, inflammation, and insulin resistance are strongly interlinked. Lisofylline (LSF), an anti-inflammatory agent, demonstrated protection against type 1 diabetes, as well as reduced obesity-induced insulin resistance and adipose tissue inflammation. However, its role in mitigating cardiac inflammation associated with obesity is not well studied. Mice were divided into 4 groups; the first group was fed regular chow diet, the second was fed regular chow diet and treated with LSF, the third was fed high fat diet (HFD), and the fourth was fed HFD and treated with LSF. Cardiac inflammation was interrogated via expression levels of TNF α, interleukins 6 and 10, phosphorylated STAT4 and lipoxygenases 12 and 12/15. Apoptosis and expression of the survival gene, AMPK, were also evaluated. We observed that LSF alleviated obesity-induced cardiac injury indirectly by improving both pancreatic β-cell function and insulin sensitivity, as well as, directly via upregulation of cardiac AMPK expression and downregulation of cardiac inflammation and apoptosis. LSF may represent an effective therapy targeting obesity-induced metabolic and cardiovascular complications.

AMPK‑SIRT1 pathway dysfunction contributes to neuron apoptosis and cognitive impairment induced by sevoflurane

The anesthetic sevoflurane (Sev) is widely used because of its low blood-gas partition coefficient and lack of pungency. However, the application of Sevmay lead to cognitive impairment later in life. Previous results have indicated that exposure to Sev-induced neuronal apoptosis and cognitive dysfunction in a rat model, but much work remains to elucidate the mechanism. In the present study, inhibition in the AMP-activated protein kinase/Sirtuin 1 (AMPK/SIRT1) signaling pathway and a decrease in AMPK/SIRT1 activity was found to occur concomitantly in neuronal apoptosis induced by Sev. AICAR, an activator of AMPK, was able to suppress Sev-induced neuronal apoptosis and SIRT1 activity reduction in vitro. Further animal studies also showed that AICAR treatment blocked the deleterious cognition and AMPK/SIRT1 activity reduction in the cognition impairment rats induced by Sev. Taken together, it was concluded that the AMPK/SIRT1 signaling pathway mediates neuronal apoptosis and cognition impairment induced by Sev. The study provides evidence that AMPK activation ameliorates Sev-induced cognitive deficits.

AMPK upregulates KCa2.3 channels and ameliorates endothelial dysfunction in diet-induced obese mice

The opening of endothelial small-conductance calcium-activated potassium channels (K_Ca2.3) is essential for endothelium-dependent hyperpolarization (EDH), which predominantly occurs in small resistance arteries. Adenosine monophosphate-activated protein kinase (AMPK), an important metabolic regulator, has been implicated in regulating endothelial nitric oxide synthase activity. However, it was unclear whether AMPK regulated endothelial K_Ca2.3-mediated EDH-type vasodilation. Using bioinformatics analysis and myograph system, we investigated the regulation by AMPK of K_Ca2.3 in human umbilical vein endothelial cells (HUVECs) or mouse second-order mesenteric resistance arteries. In HUVECs, AMPK activation either by activators (AICAR, A769662 and MK-8722) or expression of the constitutively active form of AMPK significantly upregulated K_Ca2.3 expression. Such effects were abolished by AMPK inhibitor (compound C) or AMPK α1-/α2-siRNA, extracellular-signal-regulated-kinase 5 (ERK5) inhibitor (ERK5-IN-1), and specific siRNA to myocyte-enhancer factor 2 (MEF2) or krüppel-like factor 2/4 (KLF2/4). K_Ca2.3 expression was significantly reduced in mesenteric resistance arteries in AMPKα2 knockout mice when compared with littermate control mice. Furthermore, in high-fat diet fed mice, 2-week treatment with AICAR restored endothelial K_Ca2.3 expression in mesenteric resistance arteries with improved endothelial dysfunction. Our results demonstrate that activation of AMPK upregulates K_Ca2.3 channel expression through the ERK5-MEF2-KLF2/4 signaling pathway in vascular endothelium, which contributes to benefits through K_Ca2.3-mediated EDH-type vasodilation in mesenteric resistance arteries.

An in vitro study reveals the anti-obesity effects of 7- methoxy-3-methyl-5-((E)-prop-1-enyl)-2-(3,4,5-trimethoxyphenyl)-2,3-dihydrobenzofuran from Myristica fragrans

Adipogenesis, the maturation process of preadipocytes, is closely associated with the development of obesity and other complex metabolic syndromes. Herein, we investigated the effect of 7- methoxy-3-methyl-5-((E)- prop-1-enyl)-2-(3,4,5-trimethoxyphenyl)-2,3-dihydrobenzofuran (TM), a benzofuran, isolated from the mace of Myristica fragrans Houtt on adipogenesis in 3T3-L1 preadipocytes to extrapolate whether this compound has any anti-obesity potential. For this, 3T3-L1 preadipocytes were induced to differentiate in the presence of various concentrations of TM (1, 5, 10 μM) and analyzed for triglyceride (TG) accumulation and the expression of proteins and genes involved in lipogenesis and lipolysis associated with adipogenesis. Results showed that TM significantly reduced TG accumulation and expression of marker proteins of adipocyte differentiation (peroxisome proliferator-activated receptor γ, CCAAT/enhancer-binding protein α, and fatty acid-binding protein 4) and increased the secretion of glycerol in a dose-dependent manner. There was a significant dose-dependent decrease in the expression of fatty acid synthase, stearoyl-CoA desaturase-1, sterol regulatory element-binding transcription factor 1c, and acetyl-CoA carboxylase 1 and an increase in carnitine palmitoyltransferase 1, acyl-CoA oxidase, and peroxisome proliferator-activated receptor α in TM treated cells. The phosphorylation of cAMP-activated protein kinase was also increased, which in turn activated the phosphorylation of acetyl-CoA carboxylase in mature adipocytes. Also, there was an increase in glucose uptake by TM, suggesting its insulin-sensitizing potential. This is the first report on the anti-obesity effects of TM from Myristica fragrans on adipogenesis and lipid metabolism in 3T3-L1 adipocytes and demands detailed in vivo study for developing TM as anti-obesity therapeutics.

Phosphatidylinositol 4-kinase IIIβ mediates contraction-induced GLUT4 translocation and shows its anti-diabetic action in cardiomyocytes

In the diabetic heart, long-chain fatty acid (LCFA) uptake is increased at the expense of glucose uptake. This metabolic shift ultimately leads to insulin resistance and a reduced cardiac function. Therefore, signaling kinases that mediate glucose uptake without simultaneously stimulating LCFA uptake could be considered attractive anti-diabetic targets. Phosphatidylinositol-4-kinase-IIIβ (PI4KIIIβ) is a lipid kinase downstream of protein kinase D1 (PKD1) that mediates Golgi-to-plasma membrane vesicular trafficking in HeLa-cells. In this study, we evaluated whether PI4KIIIβ is involved in myocellular GLUT4 translocation induced by contraction or oligomycin (an F₁F₀-ATP synthase inhibitor that activates contraction-like signaling). Pharmacological targeting, with compound MI14, or genetic silencing of PI4KIIIβ inhibited contraction/oligomycin-stimulated GLUT4 translocation and glucose uptake in cardiomyocytes but did not affect CD36 translocation nor LCFA uptake. Addition of the PI4KIIIβ enzymatic reaction product phosphatidylinositol-4-phosphate restored oligomycin-stimulated glucose uptake in the presence of MI14. PI4KIIIβ activation by PKD1 involves Ser294 phosphorylation and altered its localization with unchanged enzymatic activity. Adenoviral PI4KIIIβ overexpression stimulated glucose uptake, but did not activate hypertrophic signaling, indicating that unlike PKD1, PI4KIIIβ is selectively involved in GLUT4 translocation. Finally, PI4KIIIβ overexpression prevented insulin resistance and contractile dysfunction in lipid-overexposed cardiomyocytes. Together, our studies identify PI4KIIIβ as positive and selective regulator of GLUT4 translocation in response to contraction-like signaling, suggesting PI4KIIIβ as a promising target to rescue defective glucose uptake in diabetics.

The Future of Metformin in the Prevention of Diabetes-Related Osteoporosis

As a worldwide aging population is on the rise, osteoporosis (OS) is becoming a global health burden. Therefore, many researchers and health authorities are looking into the potential prevention and treatment of OS. Although previously regarded as two separate pathological processes, diabetes (DM) and OS are now regarded as two conditions that can occur together. It is now believed that OS can develop as a complication of DM. This relationship is further evidenced through a reduction in bone mineral density in type-1 diabetes with a resulting increased risk of fracture. Although bone mineral density in type-2 diabetes mellitus is normal or increased, there is also increased fragility due to decreased bone quality. These abnormal bone qualities tend to occur through the production of reduced bone microvasculature and advanced glycation end product, AGE. Interestingly, one of the most common treatments for DM, metformin (MF), shows a promising result on the protection of diabetes and non-diabetes related bone turnover. It is believed that MF modulates its effect through the adenosine monophosphate-activated protein kinase (AMPK) pathway. Recent data regarded AMPK as a vital mediator of homeostasis. It is involved not only in glucose metabolism but also in osteogenesis. AMPK can directly influence the production of mature and good quality bone by decreasing osteoclasts, increasing osteoblast formation, and enhancing bone mineral deposition. As an activator of AMPK, MF also upregulates osteogenesis. Furthermore, MF can influence osteogenesis through a non-AMPK pathway, such as the fructose 1-6 phosphatase pathway, by reducing glucose levels. While already recognized as a safe and effective treatment for DM, this article discusses whether MF can be used for the prevention and treatment of OS.

Sorghum (Sorghum bicolor) Extract Affects Plasma Lipid Metabolism and Hepatic Macrophage Infiltration in Diabetic Rats

Background:

Chronic hyperglycemia is known to be a high-risk factor for progressive chronic liver diseases, such as abnormal lipid metabolism. The activation of AMP-activated protein kinase (AMPK) has a beneficial effect on dyslipidemia. Polyphenols derived from various plants are involved in AMPK activation.

Objective:

We investigated the effects of polyphenol-containing sorghum (Sorghum bicolor) extract (SE) on plasma lipid metabolism and macrophage infiltration, and measured the expression and phosphorylation of AMPK and acetyl-CoA carboxylase (ACC) in diabetic rat livers.

Methods:

Streptozotocin-induced diabetic rats received 0, 50, or 250 mg/kg of SE orally for 4 weeks. Blood chemistry, total and phosphorylated protein levels of AMPK and ACC, sterol regulatory element- binding protein-1c (SREBP-1c) mRNA and protein levels, and macrophage infiltration in the livers were examined.

Results:

Plasma glucose and triacylglycerol levels, which were increased in the untreated diabetic rats, were significantly lower in the 250 mg/kg SE-treated diabetic rats. AMPK and ACC phosphorylation levels were significantly increased in the 250 mg/kg SE-treated diabetic rats compared with those in the untreated rats. There was no difference in the hepatic expression of SREBP-1c between the diabetic rat groups. Macrophage infiltration in the liver was suppressed by 250 mg/kg of SEtreatment.

Conclusion:

These data suggest that SE treatment may affect plasma lipid metabolism and chronic inflammation by upregulating phosphorylation of AMPK and ACC in diabetic rat livers.

Anthocyanins from Cornus kousa ethanolic extract attenuate obesity in association with anti-angiogenic activities in 3T3-L1 cells by down-regulating adipogeneses and lipogenesis

Cornus kousa the Korean dogwood has been traditionally used in East Asia as therapeutic traditional medicine however biological activities of Cornus kousa have not been investigated previously. The aim of the present study was to evaluate anti-obesity activities coupled with anti-angiogenic activities of anthocyanins rich fraction of ethanolic leaf extract of Cornus kousa (ELECk) in HUVECs and 3T3- L1 cells. Dried plants leaves were extracted with 70% ethanol and anthocyanin fraction (AnT Fr) was obtained by eluting the ethanolic extract through non-polar macroporous resin and further purification by HPLC. Antiangiogenic activities were determined by antiproliferative effect of AnT Fr on HUVECs. In the presence of various concentrations of AnT Fr, 3T3-L1 preadipocytes were induced to differentiate. Lipid accumulation in differentiated adipocytes were quantified by Oil-Red O staining. AnT Fr significantly suppressed angiogenesis by inhibiting proliferation and tube formation of HUVECs via downregulating VEGRF 2, PI3K, β-catenin, NF-kB, and Akt1 in a dose dependent manner. AnT Fr inhibited lipid accumulation by down-regulating adipogenesis and lipogenesis promoting signaling proteins, PPARγ, CCAAT, C/EBPα, aP2, FAS, and LPL, however enhanced AMPK activation to p-AMPK in 3T3 cells quantified and expressed by western blotting. AnT Fr inhibit lipid accumulation by regulating adipogenesis and lipogenesis related genes and signaling proteins. The anti-obesity activities exerted by Cornus kousa are associated with antiangiogenic activities of anthocyanins rich fraction of Cornus kousa. Hence the presence of bioactive anthocyanins, Cornus kosa, is a good candidate for nutraceutical and pharmaceutical formulation for treating or controlling obesity.

AMP-Activated Protein Kinase (AMPK)-Dependent Regulation of Renal Transport

AMP-activated kinase (AMPK) is a serine/threonine kinase that is expressed in most cells and activated by a high cellular AMP/ATP ratio (indicating energy deficiency) or by Ca²⁺. In general, AMPK turns on energy-generating pathways (e.g., glucose uptake, glycolysis, fatty acid oxidation) and stops energy-consuming processes (e.g., lipogenesis, glycogenesis), thereby helping cells survive low energy states. The functional element of the kidney, the nephron, consists of the glomerulus, where the primary urine is filtered, and the proximal tubule, Henle's loop, the distal tubule, and the collecting duct. In the tubular system of the kidney, the composition of primary urine is modified by the reabsorption and secretion of ions and molecules to yield final excreted urine. The underlying membrane transport processes are mainly energy-consuming (active transport) and in some cases passive. Since active transport accounts for a large part of the cell's ATP demands, it is an important target for AMPK. Here, we review the AMPK-dependent regulation of membrane transport along nephron segments and discuss physiological and pathophysiological implications.

Sitagliptin reduces insulin resistance and improves rat liver steatosis via the SIRT1/AMPKα pathway

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease. It is asymptomatic at presentation and is frequently identified among individuals with metabolic dysfunction, including obesity and diabetes. NAFLD is primarily characterized by the accumulation of triacylglycerol in the liver. Since insulin resistance and fat metabolism dysregulation are major causes of type 2 diabetes and NAFLD, anti-diabetes agents are widely considered as potential therapy strategies for NAFLD. Sitagliptin, an inhibitor of dipeptidyl peptidase-4, has been developed as an oral anti-hyperglycemic agent. In the present study, the effect of sitagliptin on the progression of NAFLD was evaluated in a rat model fed with a high fat diet (HFD). It was identified that sitagliptin significantly suppressed lipid accumulation in rat blood and liver and improved insulin resistance. Furthermore, it was revealed that sitagliptin reactivated the HFD-suppressed SIRT1/AMPK axis pathway and upregulated its downstream target genes, modulating fatty acid metabolism. These findings demonstrate a preventive effect of sitagliptin on hepatic lipid dysregulation and suggest that sitagliptin has potential as a clinical therapeutic strategy for NAFLD.

Standardized Kaempferia parviflora Wall. ex Baker (Zingiberaceae) Extract Inhibits Fat Accumulation and Muscle Atrophy in ob/ob Mice

Obesity, a metabolic disorder caused by an imbalance between energy intake and energy expenditure, is accompanied with fat accumulation and skeletal muscle atrophy. Kaempferia parviflora Wall. ex Baker, also called black ginger, is known to increase physical fitness performance and improve energy metabolism. In this study, we investigated whether Kaempferia parviflora extract (KPE) alleviates both obesity and muscle atrophy using ob/ob mice. Wild-type C57BL/6J and ob/ob mice were provided with a normal diet ad libitum, and ob/ob mice were orally given KPE at a dose of 100 mg/kg/day or 200 mg/kg/day for eight weeks. KPE significantly decreased body weight, fat volume, and fat weight without affecting appetite. It inhibited the expression of adipogenic transcription factors and lipogenic enzymes by upregulating AMP-activated protein kinase (AMPK) in epididymal fat. In contrast, it markedly increased the muscle fiber size, muscle volume, and muscle mass, resulting in the enhancement of muscle function, such as exercise endurance and grip strength. On the molecular level, it activated the phosphatidylinositol 3 kinase (PI3K)/Akt pathway, a key regulator in protein synthesis in skeletal muscle. KPE could be a promising material to alleviate obesity by inhibiting adipogenesis, lipogenesis, and muscle atrophy.

The Exposure to Different Photoperiods Strongly Modulates the Glucose and Lipid Metabolisms of Normoweight Fischer 344 Rats

Seasonal variations in day length trigger clear changes in the behavior, growth, food intake, and reproductive status of photoperiod-sensitive animals, such as Fischer 344 rats. However, there is little information about the effects of seasonal fluctuations in day length on glucose and lipid metabolisms and their underlying mechanisms in this model. To gain knowledge on these issues, three groups of male Fischer 344 rats were fed with a standard diet and exposed to different photoperiods for 14 weeks: normal photoperiod (L12, 12 h light/day), long photoperiod (L18, 18 h light/day), and short photoperiod (L6, 6 h light/day). A multivariate analysis carried out with 239 biometric, serum, hepatic and skeletal muscle parameters revealed a clear separation among the three groups. Compared with L12 rats, L6 animals displayed a marked alteration of glucose homeostasis and fatty acid uptake and oxidation, which were evidenced by the following observations: (1) increased circulating levels of glucose and non-esterified fatty acids; (2) a sharp down-regulation of the phosphorylated Akt2 levels, a downstream post-receptor target of insulin, in both the soleus and gastrocnemius muscles; (3) decreased expression in the soleus muscle of the glucose metabolism-related microRNA-194 and lower mRNA levels of the genes involved in glucose metabolism (Irs1, soleus, and Glut2, liver), β-oxidation (Had and Cpt1β, soleus) and fatty acid transport (Cd36, soleus, and liver). L18 animals also displayed higher blood glucose levels than L12 rats and profound changes in other glucose and lipid metabolism-related parameters in the blood, liver, and skeletal muscles. However, the mechanisms that account for the observed effects were less evident than those reported in L6 animals. In conclusion, exposure to different photoperiods strongly modulated glucose and lipid metabolisms in normoweight rats. These findings emphasize the relevance of circannual rhythms in metabolic homeostasis regulation and suggest that Fischer 344 rats are a promising animal model with which to study glucose- and lipid-related pathologies that are influenced by seasonal variations, such as obesity, cardiovascular disease and seasonal affective disorder.

Metabolic studies of a patient harbouring a novel S487L mutation in the catalytic subunit of AMPK

AMP-activated protein kinase (AMPK) regulates many different metabolic pathways in eukaryote cells including mitochondria biogenesis and energy homeostasis. Here we identify a patient with hypotonia, weakness, delayed milestones and neurological impairment since birth harbouring a novel homozygous mutation in the AMPK catalytic α-subunit 1, encoded by the PRKAA1 gene. The homozygous mutation p.S487L in isoform 1 present in the patient is in a cryptic residue for AMPK activity. In the present study, we performed the characterization of mitochondrial respiratory properties of the patient, in comparison to healthy controls, through the culture of skin fibroblasts in order to understand some of the cellular consequences of the PRKAA1 mutation. In these assays, mitochondrial respiratory complex I showed lower activity, which was followed by a decrement in the mtDNA copy number, which is a probable consequence of the lower expression of PGC-1α and PRKAA1 itself as measured in our quantitative PCRs experiments. Confirming the effect of the patient mutation in respiration, transfection of patient fibroblasts with wild type PRKAA1 partially restore complex I level. The preliminary clinic evaluations of the patient suggested a metabolic defect related to the mitochondrial respiratory function, therefore treatment with CoQ10 supplementation dose started four years ago and a clear improvement in motor skills and strength has been achieved with this treatment.

Essential role of methyl donors in animal productivity

Dietary requirements for the methyl donors, choline, betaine and folate, in livestock species are poorly defined and have not been included in diet formulation software or simulation models for animals. A deficiency of methyl donors may promote an inflammatory state, which is significant for the livestock industry because chronic low-grade inflammation is widespread among livestock under commercial conditions. Furthermore, recent evidence showing that methyl donors activate adenosine monophosphate-activated protein kinase, an anti-inflammatory master switch, indicates that dietary methyl-donor supplementation could be used to prevent or ameliorate chronic inflammation and its sequelae in livestock, which include fatty liver disease in dairy cows, fatty liver and kidney syndrome in broilers, fatty liver haemorrhagic syndrome in layers, gut ulcers in pigs, liver abscesses in feedlot cattle, enteritis in poultry and susceptibility to heat stress in all species. Because of the complexity of interactions among methyl donors, a modelling approach inclusive of a supporting research effort will be required to harness the potential of methyl-donor supplementation in livestock production.

1-Deoxynojirimycin: Sources, Extraction, Analysis and Biological Functions

1-Deoxynojirimycin (DNJ), a natural polyhydroxylated piperidine alkaloid, is attracting growing attention due to its important biological functions. This paper introduces the discovery and origins of DNJ, its extraction, purification, and physiological functions in the treatment of diabetes. The mechanisms of DNJ in the inhibition of fat accumulation and tumor cell metastasis are also discussed. In addition, the prospects and challenges of DNJ for practical production are proposed. This work aims to provide technical advice on obtaining DNJ and a fuller understanding of its biological activities.

A Hepatic GAbp-AMPK Axis Links Inflammatory Signaling to Systemic Vascular Damage

Increased pro-inflammatory signaling is a hallmark of metabolic dysfunction in obesity and diabetes. Although both inflammatory and energy substrate handling processes represent critical layers of metabolic control, their molecular integration sites remain largely unknown. Here, we identify the heterodimerization interface between the α and β subunits of transcription factor GA-binding protein (GAbp) as a negative target of tumor necrosis factor alpha (TNF-α) signaling. TNF-α prevented GAbpα and β complex formation via reactive oxygen species (ROS), leading to the non-energy-dependent transcriptional inactivation of AMP-activated kinase (AMPK) β1, which was identified as a direct hepatic GAbp target. Impairment of AMPKβ1, in turn, elevated downstream cellular cholesterol biosynthesis, and hepatocyte-specific ablation of GAbpα induced systemic hypercholesterolemia and early macro-vascular lesion formation in mice. As GAbpα and AMPKβ1 levels were also found to correlate in obese human patients, the ROS-GAbp-AMPK pathway may represent a key component of a hepato-vascular axis in diabetic long-term complications.

Small molecules as activators in medicinal chemistry (2000-2016)

INTRODUCTION

From therapeutic point of view, it is often beneficial to enhance the expression of certain enzymes whose low expression is responsible for the observed ailment. Small molecules as activators of several enzymes have great biological potential as anti-microbial and anti-cancer agents, for the treatment of diabetes, obesity, metabolic disorders, and for the treatment of neurological disorders including Alzheimer's disease. This review covers patents describing small molecules as activators, and provides structural leads for the design of even more potent activators. Area covered: This review is focused on small molecules that have been explored as activators of enzymes in the last and current decade (2000-2016). Expert opinion: The ability to modulate activity of enzymes has long been a quest of medicinal chemistry. This has been the impetus behind the development of a plethora of drugs as enzyme inhibitors. However only a few enzyme activators as drugs have made it to the market. Disorders characterized by supressed enzyme activity can be treated by enhancing the activity of a specific enzyme.

Cichoric acid regulates the hepatic glucose homeostasis via AMPK pathway and activates the antioxidant response in high glucose-induced hepatocyte injury

CA regulates hepatic glucose homeostasisviathe AMPK pathway and improves hepatocyte injuryviaantioxidant responsein vitroandin vivo.

Adiponectin-Resistance in Obesity

The decrease in adiponectin levels are negatively correlated with chronic subclinical inflammation markers in obesity. The hypertrophic adipocytes cause obesity-linked insulin resistance and metabolic syndrome. Furthermore, macrophage polarization is a key determinant regulating adiponectin receptor (AdipoR1/R2) expression and differential adiponectin-mediated macrophage inflammatory responses in obese individuals. In addition to decrease in adiponectin concentrations, the decline in AdipoR1/R2 mRNA expression leads to a decrement in adiponectin binding to cell membrane, and this turns into attenuation in the adiponectin effects. Within the receptor complex, adaptor protein-containing pleckstrin homology domain, phosphotyrosine-binding domain, and leucine zipper motif 1 (APPL1) is the intracellular binding partner of AdipoR1 and AdipoR2. The expression levels of APPL1 or APPL2 lead to an altered adiponectin activity. Despite normal or high adiponectin levels, an impaired post receptor signaling due to APPL1/APPL2 may alter adiponectin efficiency and activity. However, APPL2 blocks adiponectin signaling through AdipoR1 and AdipoR2 by competitive inhibition of APPL1. APPL1 is also an important mediator of adiponectin dependent insulin sensitization. In this context, adiponectin resistance is associated with insulin resistance and is thought to be partly due to the down-regulation of the AdipoRs in high-fat diet fed subjects. Actually, adiponectin resistance occurs very rapidly after saturated fatty acid feeding, this metabolic disturbance is not due to a decrease in AdipoR1 protein content. Intra-abdominal adipose tissue-AdipoR2 expression is reduced in obesity, whereas AdipoR1 expression is not changed. Adiponectin resistance together with insulin resistance forms a vicious cycle. The elevated adiponectin levels with adiponectin resistance is a compensatory response in the condition of an unusual discordance between insulin resistance and adiponectin unresponsiveness.Additionally, different mechanisms are involved in vascular adiponectin resistance at different stages of obesity. Nevertheless, diet-induced hyperlipidemia is the leading cause of vascular adiponectin resistance. Leptin/adiponectin imbalance may also be an important marker of the elevated risk of developing abdominal obesity-associated cardiovascular diseases.

Sugar Composition Analysis of Fuzi Polysaccharides by HPLC-MSn and Their Protective Effects on Schwann Cells Exposed to High Glucose

Fuzi has been used to treat diabetic complications for many years in china. In a previous study, we have shown that Fuzi aqueous extract can attenuate Diabetic peripheral neuropathy (DPN) in rats and protect Schwann cells from injury. Thus, the protective effect of Fuzi polysaccharides (FPS) on high glucose-induced SCs and the preliminary mechanism were investigated. Firstly, the FPS were obtained and their monose composition was analyzed by the combination of pre-column derivatization and high performance liquid chromatography coupled with electrospray ionization multi-tandem mass spectrometry (HPLC/ESI-MSⁿ). The results witnessed the efficiency of this method and seven monosaccharides were tentatively identified, among which fucose was first reported. Simultaneously, m/z 215 can be considered as diagnostic ions to confirm the number of monosaccharides. Next, high glucose-induced SC model was applied and divided into model group, treated group of FPS, normal and osmotic control group. After treatment for 48 h, the data showed FPS could significantly decrease the intracellular ROS and apoptosis, which were determined by the corresponding fluorescent probes. Then, the expression of oxidative stress-related proteins in SCs were measured by Western blot. Furthermore, the protein tests found that FPS markedly up-regulated superoxide dismutase (SOD), catalase (CAT) and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) protein level, but down-regulated NADPH oxidase-1 (Nox1) protein level. Moreover, FPS could also increase AMP-activated protein kinase (AMPK) activation significantly. Hence, we preliminary deduced that AMPK-PGC-1α pathway may play an important role in the protective effect of FPS against high glucose-induced cell damage.

A concise review on advances in development of small molecule anti-inflammatory therapeutics emphasising AMPK: An emerging target

Inflammatory diseases are complex, multi-factorial outcomes of evolutionarily conserved tissue repair processes. For decades, non-steroidal anti-inflammatory drugs and cyclooxygenase inhibitors, the primary drugs of choice for the management of inflammatory diseases, addressed individual targets in the arachidonic acid pathway. Unsatisfactory safety and efficacy profiles of the above have necessitated the development of multi-target agents to treat complex inflammatory diseases. Current anti-inflammatory therapies still fall short of clinical needs and the clinical trial results of multi-target therapeutics are anticipated. Additionally, new drug targets are emerging with improved understanding of molecular mechanisms controlling the pathophysiology of inflammation. This review presents an outline of small molecules and drug targets in anti-inflammatory therapeutics with a summary of a newly identified target AMP-activated protein kinase, which constitutes a novel therapeutic pathway in inflammatory pathology.

AMP-activated protein kinase suppresses urate crystal-induced inflammation and transduces colchicine effects in macrophages

OBJECTIVE

AMP-activated protein kinase (AMPK) is metabolic biosensor with anti-inflammatory activities. Gout is commonly associated with excesses in soluble urate and in nutrition, both of which suppress tissue AMPK activity. Gout is driven by macrophage-mediated inflammation transduced partly by NLRP3 inflammasome activation and interleukin (IL)-1β release. Hence, we tested the hypothesis that AMPK activation limits monosodium urate (MSU) crystal-induced inflammation.

METHODS

We studied bone marrow-derived macrophages (BMDMs) from AMPKα1 knockout and wild-type mice, and assessed the selective AMPK pharmacological activator A-769662 and a low concentration (10 nM) of colchicine. We examined phosphorylation (activation) of AMPKα Thr172, NLRP3 mRNA expression, and caspase-1 cleavage and IL-1β maturation using western blot and quantitative RT-PCR approaches. We also assessed subcutaneous murine air pouch inflammatory responses to MSU crystals in vivo.

RESULTS

MSU crystals suppressed phosphorylation of AMPKα in BMDMs. Knockout of AMPKα1 enhanced, and, conversely, A-769662-inhibited MSU crystal-induced inflammatory responses including IL-1β and CXCL1 release in vitro and in vivo. A-769662 promoted AMPK-dependent macrophage anti-inflammatory M2 polarisation and inhibited NLRP3 gene expression, activation of caspase-1 and IL-1β. Colchicine, at low concentration (10 nM) achieved in gout flare prophylaxis dosing, promoted phosphorylation of AMPKα and macrophage M2 polarisation, and reduced activation of caspase-1 and release of IL-1β and CXCL1 by MSU crystals in BMDMs in vitro.

CONCLUSIONS

AMPK activity limits MSU crystal inflammation in vitro and in vivo, and transduces multiple anti-inflammatory effects of colchicine in macrophages. Targeting increased and sustained AMPK activation in inflammatory cells merits further investigation for enhancing efficacy of prophylaxis and treatment of gouty inflammation.

The Dipeptidyl Peptidase-4 Inhibitor Teneligliptin Attenuates Hepatic Lipogenesis via AMPK Activation in Non-Alcoholic Fatty Liver Disease Model Mice

Non-alcoholic fatty liver disease (NAFLD), which is strongly associated with metabolic syndrome, is increasingly a major cause of hepatic disorder. Dipeptidyl peptidase (DPP)-4 inhibitors, anti-diabetic agents, are expected to be effective for the treatment of NAFLD. In the present study, we established a novel NAFLD model mouse using monosodium glutamate (MSG) and a high-fat diet (HFD) and investigated the effects of a DPP-4 inhibitor, teneligliptin, on the progression of NAFLD. Male MSG/HFD-treated mice were divided into two groups, one of which received teneligliptin in drinking water. Administration of MSG and HFD caused mice to develop severe fatty changes in the liver, but teneligliptin treatment improved hepatic steatosis and inflammation, as evaluated by the NAFLD activity score. Serum alanine aminotransferase and intrahepatic triglyceride levels were significantly decreased in teneligliptin-treated mice (p < 0.05). Hepatic mRNA levels of the genes involved in de novo lipogenesis were significantly downregulated by teneligliptin (p < 0.05). Moreover, teneligliptin increased hepatic expression levels of phosphorylated AMP-activated protein kinase (AMPK) protein. These findings suggest that teneligliptin attenuates lipogenesis in the liver by activating AMPK and downregulating the expression of genes involved in lipogenesis. DPP-4 inhibitors may be effective for the treatment of NAFLD and may be able to prevent its progression to non-alcoholic steatohepatitis.

Early ALS-type gait abnormalities in AMP-dependent protein kinase-deficient mice suggest a role for this metabolic sensor in early stages of the disease

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the selective loss of motoneurons. While the principal cause of the disease remains so far unknown, the onset and progression of the pathology are increasingly associated with alterations in the control of cell metabolism. On the basis of the well-known key roles of 5'-adenosine monophosphate-activated protein kinase (AMPK) in sensing and regulating the intracellular energy status, we hypothesized that mice with a genetic deletion of AMPK would develop locomotor abnormalities that bear similarity with those detected in the very early disease stage of mice carrying the ALS-associated mutated gene hSOD1(G93A). Using an automated gait analysis system (CatWalk), we here show that hSOD1(G93A) mice and age-matched mice lacking the neuronal and skeletal muscle predominant α2 catalytic subunit of AMPK showed an altered gait, clearly different from wild type control mice. Double mutant mice lacking AMPK α2 and carrying hSOD1(G93A) showed the same early gait abnormalities as hSOD1(G93A) mice over an age span of 8 to 16 weeks. Taken together, these data support the concept that altered AMPK function and associated bioenergetic abnormalities could constitute an important component in the early pathogenesis of ALS. Therapeutic interventions acting on metabolic pathways could prove beneficial on early locomotor deficits, which are sensitively detectable in rodent models using the CatWalk system.

Regulation of liver cell glucose homeostasis by dehydroabietic acid, abietic acid and squalene isolated from balsam fir (Abies balsamea (L.) Mill.) a plant of the Eastern James Bay Cree traditional pharmacopeia

In our previous study, Abies balsamea (L.) Mill., a plant used in Cree traditional medicine, had a strong effect on the regulation of glucose homeostasis in liver cells. This study aimed to isolate and identify its active constituents using a bioassay-guided fractionation approach as well as to elucidate their mechanism(s) of action. The effect of the crude extract and its constituents was evaluated on the activity of Glucose-6-Phosphatase (G6Pase) and Glycogen Synthase (GS) and phosphorylation of three kinases, AMP-activated protein kinase (AMPK), Akt and Glycogen Synthase Kinase-3 (GSK-3). Three compounds, abietic acid, dehydroabietic acid and squalene, were isolated from the most active fraction in the bioassays (hexane). The compounds were able to decrease the activity of G6Pase and to stimulate GS. Their effect on G6Pase activity involved both Akt and AMPK phosphorylation with significant correlations between insulin-dependent and -independent pathways and the bioassay. In addition, the compounds were able to stimulate GS through GSK-3 phosphorylation with a significant correlation between the signaling pathway and the bioassay. Dehydroabietic acid stood out for its strongest effect in all the experiments close to that of the crude extract. These compounds may have potential applications in the treatment of type 2 diabetes and insulin resistance.

Cardiac contraction-induced GLUT4 translocation requires dual signaling input

Contraction-induced translocation of glucose transporter type-4 (GLUT4) to the sarcolemma is essential to stimulate cardiac glucose uptake during increased energy demand. As such, this process is a target for therapeutic strategies aiming at increasing glucose uptake in insulin-resistant and/or diabetic hearts. AMP-activated protein kinase (AMPK) and its upstream kinases form part of a signaling axis essential for contraction-induced GLUT4 translocation. Recently, activation of protein kinase-D1 (PKD1) was also shown to be as obligatory for contraction-induced GLUT4 translocation in cardiac muscle. However, contraction-induced PKD1 activation in this context occurs independently from AMPK signaling, suggesting that contraction-induced GLUT4 translocation requires the input of two separate signaling pathways. Necessity for dual input would more tightly couple GLUT4 translocation to stimuli that are inherent to cardiac contraction.

Vascular AMPK as an attractive target in the treatment of vascular complications of obesity

The key for the survival of all organisms is the regulation and control of energy metabolism. Thus, several strategies have evolved in each tissue in order to balance nutrient supply with energy demand. Adenosine monophosphate-activated protein kinase (AMPK) is now recognized as a key participant in energy metabolism. It ensures an appropriate energetic supply by promoting energy conserving pathways in detriment of anabolic processes not essential for cell survival. Vascular AMPK plays a critical role in the regulation of blood flow and vascular tone through several mechanisms, including vasodilation by stimulating nitric oxide release in endothelial cells. Since obesity leads to endothelial damage and AMPK dysregulation, AMPK activation might be an important strategy to restore vascular function in cardiometabolic alterations. In the present review we focus on the role of vascular AMPK in both endothelial and smooth muscle cells, paying special attention to its dysregulation in obesity- and high-fat diet-related complications, as well as to the mechanisms and benefits of vascular AMPK activation.

Hypolipidemic activity of Taraxacum mongolicum associated with the activation of AMP-activated protein kinase in human HepG2 cells

This study investigated the hypolipidemic effect and potential mechanisms of T. mongolicum extracts. T. mongolicum was extracted by refluxing three times with water (TM-1), 50% ethanol (TM-2) and 95% ethanol (TM-3). TM-2 contained components with the most effective hypolipidemic potentials in HepG2 cells. Extended administration of TM-2 stimulated a significant reduction in body weight and levels of serum triglyceride LDL-C and total cholesterol in rats. To evaluate the bioactive compounds, we successively fractionated TM-2 with n-hexane (TM-4), dichloromethane (TM-5), ethyl acetate (TM-6), and water (TM-7). TM-4 fraction had the most effective hypolipidemic potential in HepG2 cells, and it decreased the expression of fatty acid synthase (FASN) and inhibited the activity of acetyl-coenzyme A carboxylase (ACC) through the phosphorylation of AMP-activated protein kinase (AMPK). Linoleic acid, phytol and tetracosanol are bioactive compounds identified from TM-4. These results suggest that T. mongolicum is expected to be useful for hypolipidemic effects.