AMP-activated protein kinase in the regulation of hepatic energy metabolism: from physiology to therapeutic perspectives

Transcriptomic analysis reveals pharmacological mechanisms mediating efficacy of Yangyinghuoxue Decoction in CCl4-induced hepatic fibrosis in rats

Background and purpose

As a traditional Chinese medicine formula, Yangyinghuoxue Decoction (YYHXD) is used clinically for therapy of hepatic fibrosis. The pharmacological profile of YYHXD comprises multiple components acting on many targets and pathways, but the pharmacological mechanisms underlying its efficacy have not been thoroughly elucidated. This study aimed at probing the pharmacological mechanisms of YYHXD in the treatment of hepatic fibrosis.

Methods

YYHXD aqueous extract was prepared and quality control using HPLC-MS fingerprint analysis was performed. A CCl4-induced rat model of hepatic fibrosis was established, and animals were randomly assigned to six groups: control, low-dose YYHXD (L-YYHXD), medium-dose YYHXD (M-YYHXD), high-dose YYHXD (H-YYHXD), CCl4 model, and colchicine group. Rats in the treatment groups received daily oral administration of YYHXD (5, 10, or 20 g/kg) or colchicine (0.2 mg/kg) for 6 weeks, while the control and model groups received distilled water. Histological analysis, including hematoxylin and eosin (HE) and Masson's trichrome staining, was performed to evaluate hepatic fibrosis. Serum biochemical markers, such as AST, ALT, HA, and LN, were measured. Inflammatory cytokines (IL-6 and TNF-α) and oxidative stress indicators (SOD, GSH-Px, and MDA) in hepatic tissue were also assessed. Additionally, transcriptomic analysis using RNA-sequencing was conducted to identify differentially expressed genes (DEGs) between the control, CCl4 model, and H-YYHXD groups. Bioinformatics analysis, including differential expression analysis, protein-protein interaction analysis, and functional enrichment analysis, were performed to probe the pharmacological mechanisms of YYHXD. The regulatory effects of YYHXD on fatty acid metabolism and biosynthesis were further confirmed by Oil Red O staining, enzyme activity assays, qPCR, and Western blotting. Western blotting and immunofluorescence staining also validated the involvement of the AMPK signaling pathway in the occurrence and progression of hepatic fibrosis.

Results

HE and Masson's trichrome staining revealed reduced collagen deposition and improved liver architecture in YYHXD groups compared to the CCl4 model group. Serum biochemical markers, including AST, ALT, HA, and LN, were significantly improved in the YYHXD-treated groups compared to the CCl4 model group. The levels of inflammatory cytokines (IL-6 and TNF-α) and oxidative stress indicators (decreased SOD and GSH-Px, increased MDA) in hepatic tissue were significantly ameliorated by YYHXD treatment compared to the CCl4 model group. Moreover, 96 genes implicated in YYHXD therapy of hepatic fibrosis were screened from the transcriptomic data, which were principally enriched in biological pathways such as fatty acid metabolism and biosynthesis, and the AMPK signaling pathway. Oil Red O staining showed reduced hepatic lipid accumulation by YYHXD in a dose-dependent manner, along with decreased serum TG, TC, and LDL-C levels. Additionally, qPCR and Western blot analyses demonstrated upregulated mRNA and protein expression of key enzymes involved in fatty acid metabolism and biosynthesis, Fasn and Fads2, modulated by YYHXD. YYHXD also dose-dependently enhanced phosphorylation of AMPK as evidenced by Western blotting and immunofluorescence assays.

Conclusion

YYHXD ameliorated CCl4-induced hepatic fibrosis in rats through pharmacological mechanisms that involved manifold targets and pathways, including aliphatic acid synthesis and metabolism pathways and the AMPK signaling pathway. This study provided a reference and basis for further research and clinical utilization of YYHXD.

Anti-Inflammatory Potential of the Anti-Diabetic Drug Metformin in the Prevention of Inflammatory Complications and Infectious Diseases Including COVID-19: A Narrative Review

Metformin, a widely used first-line anti-diabetic therapy for the treatment of type-2 diabetes, has been shown to lower hyperglycemia levels in the blood by enhancing insulin actions. For several decades this drug has been used globally to successfully control hyperglycemia. Lactic acidosis has been shown to be a major adverse effect of metformin in some type-2 diabetic patients, but several studies suggest that it is a typically well-tolerated and safe drug in most patients. Further, recent studies also indicate its potential to reduce the symptoms associated with various inflammatory complications and infectious diseases including coronavirus disease 2019 (COVID-19). These studies suggest that besides diabetes, metformin could be used as an adjuvant drug to control inflammatory and infectious diseases. In this article, we discuss the current understanding of the role of the anti-diabetic drug metformin in the prevention of various inflammatory complications and infectious diseases in both diabetics and non-diabetics.

Crosstalk between lipid metabolism and EMT: emerging mechanisms and cancer therapy

Lipids are the key component of all membranes composed of a variety of molecules that transduce intracellular signaling and provide energy to the cells in the absence of nutrients. Alteration in lipid metabolism is a major factor for cancer heterogeneity and a newly identified cancer hallmark. Reprogramming of lipid metabolism affects the diverse cancer phenotypes, especially epithelial-mesenchymal transition (EMT). EMT activation is considered to be an essential step for tumor metastasis, which exhibits a crucial role in the biological processes including development, wound healing, and stem cell maintenance, and has been widely reported to contribute pathologically to cancer progression. Altered lipid metabolism triggers EMT and activates multiple EMT-associated oncogenic pathways. Although the role of lipid metabolism-induced EMT in tumorigenesis is an attractive field of research, there are still significant gaps in understanding the underlying mechanisms and the precise contributions of this interplay. Further study is needed to clarify the specific molecular mechanisms driving the crosstalk between lipid metabolism and EMT, as well as to determine the potential therapeutic implications. The increased dependency of tumor cells on lipid metabolism represents a novel therapeutic target, and targeting altered lipid metabolism holds promise as a strategy to suppress EMT and ultimately inhibit metastasis.

The α subunit of AMP-activated protein kinase is critical for the metabolic success and tachyzoite proliferation of Toxoplasma gondii

Toxoplasma gondii is a zoonotic parasite infecting humans and nearly all warm-blooded animals. Successful parasitism in diverse hosts at various developmental stages requires the parasites to fine tune their metabolism according to environmental cues and the parasite's needs. By manipulating the β and γ subunits, we have previously shown that AMP-activated protein kinase (AMPK) has critical roles in regulating the metabolic and developmental programmes. However, the biological functions of the α catalytic subunit have not been established. T. gondii encodes a canonical AMPKα, as well as a KIN kinase whose kinase domain has high sequence similarities to those of classic AMPKα proteins. Here, we found that TgKIN is dispensable for tachyzoite growth, whereas TgAMPKα is essential. Depletion of TgAMPKα expression resulted in decreased ATP levels and reduced metabolic flux in glycolysis and the tricarboxylic acid cycle, confirming that TgAMPK is involved in metabolic regulation and energy homeostasis in the parasite. Sequential truncations at the C-terminus found an α-helix that is key for the function of TgAMPKα. The amino acid sequences of this α-helix are not conserved among various AMPKα proteins, likely because it is involved in interactions with TgAMPKβ, which only have limited sequence similarities to AMPKβ in other eukaryotes. The essential role of the less conserved C-terminus of TgAMPKα provides opportunities for parasite specific drug designs targeting TgAMPKα.

Extracts of tropical green seaweed Caulerpa lentillifera reduce hepatic lipid accumulation by modulating lipid metabolism molecules in HepG2 cells

Seaweed has attracted attention as a bioactive source for preventing different chronic diseases, including liver injury and non-alcoholic fatty liver disease, the leading cause of liver-related mortality. Caulerpa lentillifera is characterized as tropical edible seaweed, currently being investigated for health benefits of its extracts and bioactive substances. This study examined the effects of C. lentillifera extract in ethyl acetate fraction (CLEA) on controlling lipid accumulation and lipid metabolism in HepG2 cells induced with oleic acid through the in vitro hepatic steatosis model. Gas chromatography-mass spectrometry (GC-MS) analysis indicated that CLEA contained diverse organic compounds, including hydrocarbons, amino acids, and carboxylic acids. Docked conformation of dl-2-phenyltryptophane and benzoic acid, two major bioactive CLEA components, showed high affinity binding to SIRT1 and AMPK as target molecules of lipid metabolism. CLEA reduced lipid accumulation and intracellular triglyceride levels in HepG2 cells stimulated with oleic acid. The effect of CLEA on regulating expression of lipid metabolism-related molecules was investigated by qPCR and immunoblotting. CLEA promoted expression of the SIRT1 gene in oleic acid-treated HepG2 cells. CLEA also reduced expression levels of SREBF1, FAS, and ACC genes, which might be related to activation of AMPK signaling in lipid-accumulated HepG2 cells. These findings suggest that CLEA contains bioactive compounds potentially reducing triglyceride accumulation in lipid-accumulated HepG2 hepatocytes by controlling lipid metabolism molecules.

Metformin and the Liver: Unlocking the Full Therapeutic Potential

Metformin is a highly effective medication for managing type 2 diabetes mellitus. Recent studies have shown that it has significant therapeutic benefits in various organ systems, particularly the liver. Although the effects of metformin on metabolic dysfunction-associated steatotic liver disease and metabolic dysfunction-associated steatohepatitis are still being debated, it has positive effects on cirrhosis and anti-tumoral properties, which can help prevent the development of hepatocellular carcinoma. Furthermore, it has been proven to improve insulin resistance and dyslipidaemia, commonly associated with liver diseases. While more studies are needed to fully determine the safety and effectiveness of metformin use in liver diseases, the results are highly promising. Indeed, metformin has a terrific potential for extending its full therapeutic properties beyond its traditional use in managing diabetes.

Hepatoprotective Effect of Lactiplantibacillus plantarum DSR330 in Mice with High Fat Diet-Induced Nonalcoholic Fatty Liver Disease

Lactiplantibacillus plantarum DSR330 (DSR330) has been examined for its antimicrobials production and probiotics. In this study, the hepatoprotective effects of DSR330 were examined against non-alcoholic fatty liver disease (NAFLD) in a high-fat diet (HFD)-fed C57BL/6 mouse model. To induce the development of fatty liver, a HFD was administered for five weeks, and then silymarin (positive control) or DSR330 (108 or 109 CFU/day) was administered along with the HFD for seven weeks. DSR330 significantly decreased body weight and altered serum and hepatic lipid profiles, including a reduction in triglyceride, total cholesterol, and low-density lipoprotein cholesterol levels compared to those in the HFD group. DSR330 significantly alleviated HFD-related hepatic injury by inducing morphological changes and reducing the levels of biomarkers, including AST, ALT, and ALP. Additionally, DSR330 alleviated the expression of SREBP-1c, ACC1, FAS, ACO, PPARα, and CPT-1 in liver cells. Insulin and leptin levels were decreased by DSR330 compared to those observed in the HFD group. However, adiponectin levels were increased, similar to those observed in the ND group. These results demonstrate that L. plantarum DSR330 inhibited HFD-induced hepatic steatosis in mice with NAFLD by modulating various signaling pathways. Hence, the use of probiotics can lead to hepatoprotective effects.

Role of Natural Compounds Modulating Heme Catabolic Pathway in Gut, Liver, Cardiovascular, and Brain Diseases

The crucial physiological process of heme breakdown yields biliverdin (BV) and bilirubin (BR) as byproducts. BV, BR, and the enzymes involved in their production (the "yellow players-YP") are increasingly documented as endogenous modulators of human health. Mildly elevated serum bilirubin concentration has been correlated with a reduced risk of multiple chronic pro-oxidant and pro-inflammatory diseases, especially in the elderly. BR and BV per se have been demonstrated to protect against neurodegenerative diseases, in which heme oxygenase (HMOX), the main enzyme in the production of pigments, is almost always altered. HMOX upregulation has been interpreted as a tentative defense against the ongoing pathologic mechanisms. With the demonstration that multiple cells possess YP, their propensity to be modulated, and their broad spectrum of activity on multiple signaling pathways, the YP have assumed the role of an adjustable system that can promote health in adults. Based on that, there is an ongoing effort to induce their activity as a therapeutic option, and natural compounds are an attractive alternative to the goal, possibly requiring only minimal changes in the life style. We review the most recent evidence of the potential of natural compounds in targeting the YP in the context of the most common pathologic condition of adult and elderly life.

Oleuropein-Rich Jasminum Grandiflorum Flower Extract Regulates the LKB1-PGC-1α Axis Related to the Attenuation of Hepatocellular Lipid Dysmetabolism

Diets() rich in fat are a major() cause() of metabolic disease(), and nutritional() food has been widely() used() to counteract the metabolic disorders such() as obesity() and fatty() liver(). The present study investigated the effects of oleuropein-enriched extract() from Jasminum grandiflorum L. flowers (OLE-JGF) in high-fat diet() (HFD)-fed mice and oleic acid() (OA)-treated AML-12 cells. Treatment() of HFD-fed mice with 0.6% OLE-JGF for 8 weeks significantly reduced body and liver() weights, as well as attenuating lipid dysmetabolism and hepatic steatosis. OLE-JGF administration() prominently suppressed the mRNA expressions() of monocyte chemoattractant protein()-1 (MCP-1) and cluster of differentiation 68 (CD68), and it also downregulated acetyl-CoA carboxylase (ACC) and fatty() acid() synthase (FAS) as well as sterol-regulatory-element()-binding protein() (SREBP-1c) in the liver(). Meanwhile, mitochondrial DNA and uncoupling protein() 2 (UCP2) were upregulated along with the increased expression() of mitochondrial biogenic promoters including liver() kinase B1 (LKB1), peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), nuclear() factor()-erythroid-derived 2-like 2 (Nrf2), and mitochondrial transcription factor() A (Tfam), but did not change AMP-activated protein() kinase (AMPK) in liver(). The lipid droplets were decreased significantly after treatment() with 80 μM oleuropein for 24 h in OA-induced AML-12 cells. Furthermore, oleuropein significantly inhibited ACC mRNA expression() and upregulated LKB1, PGC-1α, and Tfam mRNA levels, as well as increasing the binding level of LKB1 to PGC-1α promoter in OA-induced cells. These findings indicate() that OLE-JGF reduces hepatic lipid deposition in HFD-fed mice, as well as the fact that OA-induced liver() cells may be partly() attributed to upregulation of the LKB1-PGC-1α axis, which mediates hepatic lipogenesis and mitochondrial biogenesis. Our study provides a scientific() basis() for the benefits and potential() use() of the J. grandiflorum flower as a food supplement() for the prevention() and treatment() of metabolic disease().

Dehulled Adlay (Coix lachryma-jobi L.) ameliorates hepatic gluconeogenesis and steatosis in streptozotocin/high-fat diet-induced diabetic rats

Adlay (Coix lachryma-jobi L.) is a traditional Chinese herbal medicine with various biological activities. We investigated the anti-diabetic effects of different parts of adlay seeds, including polished adlay (PA), adlay bran (AB) and dehulled adlay (DA) in a streptozotocin (STZ)/high fat diet (HFD) diabetic rat model (DM). DM rats supplemented with or without PA (43%), AB (3%), or DA (46%) diet for 8 weeks. The plasma glucose and insulin levels and the insulin resistance index (HOMA-IR) were increased in DM group; among the three adlay diets, DA has the best effects attenuating all of these alterations in DM rats. Both AB and DA alleviated diabetes-impaired glucose tolerance. The increased hepatic phosphoenolpyruvate carboxykinase protein expression in DM group was improved by all of the three adlay diets. The increased ratio of glucose-6-phosphatase to glucokinase in DM group was suppressed by DA supplementation, further suggesting DA diet is most effective among the three diets. Both AB and DA diets had beneficial effects against hepatic steatosis, with better effects observed in DA group. These results suggest that the DA diet, composed of both polished adlay and adlay bran, possesses the best potential to improve glucose homeostasis, at least in part, by alleviating hepatic glucose metabolism and steatosis.

Mitochondrial metabolic flexibility is critical for CD8+ T cell antitumor immunity

Mitochondria use different substrates for energy production and intermediatory metabolism according to the availability of nutrients and oxygen levels. The role of mitochondrial metabolic flexibility for CD8+ T cell immune response is poorly understood. Here, we report that the deletion or pharmacological inhibition of protein tyrosine phosphatase, mitochondrial 1 (PTPMT1) significantly decreased CD8+ effector T cell development and clonal expansion. In addition, PTPMT1 deletion impaired stem-like CD8+ T cell maintenance and accelerated CD8+ T cell exhaustion/dysfunction, leading to aggravated tumor growth. Mechanistically, the loss of PTPMT1 critically altered mitochondrial fuel selection-the utilization of pyruvate, a major mitochondrial substrate derived from glucose-was inhibited, whereas fatty acid utilization was enhanced. Persistent mitochondrial substrate shift and metabolic inflexibility induced oxidative stress, DNA damage, and apoptosis in PTPMT1 knockout cells. Collectively, this study reveals an important role of PTPMT1 in facilitating mitochondrial utilization of carbohydrates and that mitochondrial flexibility in energy source selection is critical for CD8+ T cell antitumor immunity.

Potentilla fulgens upregulate GLUT4, AMPK, AKT and insulin in alloxan-induced diabetic mice: an in vivo and in silico study

OBJECTIVE

This study was designed to investigate whether the glucose lowering effects of Potentilla fulgens acts by modulating GLUT4, AKT2 and AMPK expression in the skeletal muscle and liver tissues.

METHODOLOGY

Alloxan-induced diabetic mice treated with Potentilla fulgens was assessed for their blood glucose and insulin level, mRNA and protein expression using distinguished methods. Additionally, GLUT4, AKT2 and AMPK were docked with catechin, epicatechin, kaempferol, metformin, quercetin and ursolic acid reportedly present in Potentilla fulgens.

RESULTS

Potentilla fulgens ameliorates hyperglycaemia and insulin sensitivity via activation of AKT2 and AMPK, increases the expression of GLUT4, AKT2, AMPKα1 and AMPKα2 whose levels are reduced under diabetic condition. Molecular docking revealed interacting residues and their binding affinities (-4.56 to -8.95 Kcal/mol).

CONCLUSIONS

These findings provide more clarity vis-avis the mechanism of action of the phytoceuticals present in Potentilla fulgens extract which function through their action on GLUT4, PKB and AMPK.

Chromogranin A and its derived peptides: potential regulators of cholesterol homeostasis

Chromogranin A (CHGA), a member of the granin family of proteins, has been an attractive therapeutic target and candidate biomarker for several cardiovascular, neurological, and inflammatory disorders. The prominence of CHGA stems from the pleiotropic roles of several bioactive peptides (e.g., catestatin, pancreastatin, vasostatins) generated by its proteolytic cleavage and by their wide anatomical distribution. These peptides are emerging as novel modulators of cardiometabolic diseases that are often linked to high blood cholesterol levels. However, their impact on cholesterol homeostasis is poorly understood. The dynamic nature of cholesterol and its multitudinous roles in almost every aspect of normal body function makes it an integral component of metabolic physiology. A tightly regulated coordination of cholesterol homeostasis is imperative for proper functioning of cellular and metabolic processes. The deregulation of cholesterol levels can result in several pathophysiological states. Although studies till date suggest regulatory roles for CHGA and its derived peptides on cholesterol levels, the mechanisms by which this is achieved still remain unclear. This review aims to aggregate and consolidate the available evidence linking CHGA with cholesterol homeostasis in health and disease. In addition, we also look at common molecular regulatory factors (viz., transcription factors and microRNAs) which could govern the expression of CHGA and genes involved in cholesterol homeostasis under basal and pathological conditions. In order to gain further insights into the pathways mediating cholesterol regulation by CHGA/its derived peptides, a few prospective signaling pathways are explored, which could act as primers for future studies.

The interplay between macronutrients and sleep: focus on circadian and homeostatic processes

Sleep disturbances are an emerging risk factor for metabolic diseases, for which the burden is particularly worrying worldwide. The importance of sleep for metabolic health is being increasingly recognized, and not only the amount of sleep plays an important role, but also its quality. In this review, we studied the evidence in the literature on macronutrients and their influence on sleep, focusing on the mechanisms that may lay behind this interaction. In particular, we focused on the effects of macronutrients on circadian and homeostatic processes of sleep in preclinical models, and reviewed the evidence of clinical studies in humans. Given the importance of sleep for health, and the role of circadian biology in healthy sleep, it is important to understand how macronutrients regulate circadian clocks and sleep homeostasis.

Rice Bran Extract Suppresses High-Fat Diet-Induced Hyperlipidemia and Hepatosteatosis through Targeting AMPK and STAT3 Signaling

Rice bran, a by-product of rice milling, is abundant in bioactive molecules and is highly recognized for its health-promoting properties, particularly in improving metabolic conditions. Building on this knowledge, we aimed to optimize the extraction conditions to maximize the functional efficacy of rice bran extract (RBE) and further validate its impact on lipid metabolism. We found that the optimized RBE (ORBE) significantly suppressed high-fat diet-induced weight gain, hyperlipidemia, and hepatosteatosis in mouse models. ORBE treatment not only suppressed lipid uptake in vivo, but also reduced lipid accumulation in HepG2 cells. Importantly, we discovered that ORBE administration resulted in activation of AMPK and inhibition of STAT3, which are both crucial players in lipid metabolism in the liver. Collectively, ORBE potentially offers promise as a dietary intervention strategy against hyperlipidemia and hepatosteatosis. This study underlines the value of optimized extraction conditions in enhancing the functional efficacy of rice bran.

Liver acts as a metabolic gate for the traumatic brain injury pathology: Protective action of thyroid hormone

Clinical evidence indicates that injury to the brain elicits systemic metabolic disturbances that contributes to the brain pathology. Since dietary fructose is metabolized in the liver, we explored mechanisms by which traumatic brain injury (TBI) and dietary fructose influence liver function and their possible repercussions to brain. Consumption of fructose contributed to the detrimental effects of TBI on liver operation, in terms of glucose and lipid metabolism, de novo lipogenesis, lipid peroxidation. Thyroid hormone (T4) is metabolized in the liver and found that T4 supply improved lipid metabolism by reducing de novo lipogenesis, lipid accumulation, lipogenic enzymes (ACC, AceCS1, FAS), lipid peroxidation in liver in response to fructose and fructose-TBI. T4 supply also helped to normalize glucose metabolism and improve insulin sensitivity. Furthermore, T4 counteracted elevations of the pro-inflammatory cytokines, Tnfα and Mcp-1 after TBI and/or fructose intake in liver and circulation. T4 also exerted an effect on isolated primary hepatocytes by potentiating phosphorylation of AMPKα and AKT substrate, AS160, leading to increased glucose uptake. In addition, T4 restored the metabolism of DHA in the liver disrupted by TBI and fructose, adding important information to optimize the action of DHA in therapeutics. The overall evidence seems to indicate that the liver works as a gate for the regulation of the effects of brain injury and foods on brain pathologies.

Effect of DHCR7 for the co-occurrence of hypercholesterolemia and vitamin D deficiency in type 2 diabetes: Perspective of health prevention

Type 2 diabetes mellitus (T2DM) is a complex disease caused by multiple factors, which are often accompanied by the disorder of glucose and lipid metabolism and the lack of vitamin D.Over the years, researchers have conducted numerous studies into the pathogenesis and prevention strategies of diabetes. In this study, diabetic SD rats were randomly divided into type 2 diabetes group, vitamin D intervention group, 7-dehydrocholesterole reductase (DHCR7) inhibitor intervention group, simvastatin intervention group, and naive control group. Before and 12 weeks after intervention, liver tissue was extracted to isolate hepatocytes. Compared with naive control group, in the type 2 diabetic group without interference, the expression of DHCR7 increased, the level of 25(OH)D3 decreased, the level of cholesterol increased. In the primary cultured naive and type 2 diabetic hepatocytes, the expression of genes related to lipid metabolism and vitamin D metabolism were differently regulated in each of the 5 treatment groups. Overall, DHCR7 is an indicator for type 2 diabetic glycolipid metabolism disorder and vitamin D deficiency. Targeting DHCR7 will help with T2DM therapy.The management model of comprehensive health intervention can timely discover the disease problems of diabetes patients and high-risk groups and reduce the incidence of diabetes.

Starvation Protects Hepatocytes from Inflammatory Damage through Paradoxical mTORC1 Signaling

Background and aims: Sepsis-related liver failure is associated with a particularly unfavorable clinical outcome. Calorie restriction is a well-established factor that can increase tissue resilience, protect against liver failure and improve outcome in preclinical models of bacterial sepsis. However, the underlying molecular basis is difficult to investigate in animal studies and remains largely unknown.

METHODS

We have used an immortalized hepatocyte line as a model of the liver parenchyma to uncover the role of caloric restriction in the resilience of hepatocytes to inflammatory cell damage. In addition, we applied genetic and pharmacological approaches to investigate the contribution of the three major intracellular nutrient/energy sensor systems, AMPK, mTORC1 and mTORC2, in this context.

RESULTS

We demonstrate that starvation reliably protects hepatocytes from cellular damage caused by pro-inflammatory cytokines. While the major nutrient- and energy-related signaling pathways AMPK, mTORC2/Akt and mTORC1 responded to caloric restriction as expected, mTORC1 was paradoxically activated by inflammatory stress in starved, energy-deprived hepatocytes. Pharmacological inhibition of mTORC1 or genetic silencing of the mTORC1 scaffold Raptor, but not its mTORC2 counterpart Rictor, abrogated the protective effect of starvation and exacerbated inflammation-induced cell death. Remarkably, mTORC1 activation in starved hepatocytes was uncoupled from the regulation of autophagy, but crucial for sustained protein synthesis in starved resistant cells.

CONCLUSIONS

AMPK engagement and paradoxical mTORC1 activation and signaling mediate protection against pro-inflammatory stress exerted by caloric restriction in hepatocytes.

Structure-activity relationship, bioactivities, molecular mechanisms, and clinical application of nuciferine on inflammation-related diseases

Nuciferine aporphine alkaloid mainly exists in Nelumbo nucifera Gaertn and is a beneficial to human health, such as anti-obesity, lowering blood lipid, prevention of diabetes and cancer, closely associated with inflammation. Importantly, nuciferine may contribute to its bioactivities by exerting intense anti-inflammatory activities in multiple models. However, no review has summarized the anti-inflammatory effect of nuciferine. This review critically summarized the information regarding the structure-activity relationships of dietary nuciferine. Moreover, biological activities and clinical application on inflammation-related diseases, such as obesity, diabetes, liver, cardiovascular diseases, and cancer, as well as their potential mechanisms, involving oxidative stress, metabolic signaling, and gut microbiota has been reviewed. The current work provides a better understanding of the anti-inflammation properties of nuciferine against multiple diseases, thereby improving the utilization and application of nuciferine-containing plants across functional food and medicine.

Elnosary M, L. Ashour M, M. Abd El-Moneam N, A. Shreadah M. Flavonoids Biosynthesis in Plants as a Defense Mechanism: Role and Function Concerning Pharmacodynamics and Pharmacokinetic Properties

Flavonoids are a major class of secondary metabolites that comprises more than 6000 compounds that have been identified. They are biosynthesized via the phenylpropanoid metabolic pathway that involves groups of enzymes such as isomerases, hydroxylases, and reductases that greatly affect the determination of the flavonoid skeleton. For example, transferase enzymes responsible for the modification of sugar result in changes in the physiological activity of the flavonoids and changes in their physical properties, such as solubility, reactivity, and interaction with cellular target molecules, which affect their pharmacodynamics and pharmacokinetic properties. In addition, flavonoids have diverse biological activities such as antioxidants, anticancer, and antiviral in managing Alzheimer’s disease. However, most marine flavonoids are still incompletely discovered because marine flavonoid biosynthesis is produced and possesses unique substitutions that are not commonly found in terrestrial bioactive compounds. The current chapter will illustrate the importance of flavonoids’ role in metabolism and the main difference between marine and terrestrial flavonoids.

A clinical experience-based Chinese herbal formula improves ethanol-induced drunken behavior and hepatic steatohepatitis in mice models

BACKGROUND

Bao-Gan-Xing-Jiu-Wan (BGXJW) is a clinical experience-based Chinese herbal formula. Its efficacy, pharmacological safety, targeted function, process quality, and other aspects have met the evaluation standards and the latest requirements of preparations. It could prevent and alleviate the symptoms of drunkenness and alcoholic liver injury clinically. The present work aims to elucidate whether BGXJW could protect against drunkenness and alcoholic liver disease in mice and explore the associated mechanism.

MATERIAL AND METHODS

We used acute-on-chronic (NIAAA) mice model to induce alcoholic steatosis, and alcohol binge-drinking model to reappear the drunk condition. BGXJW at indicated doses were administered by oral gavage respectively to analyze its effects on alcoholic liver injury and the associated molecular mechanisms.

RESULTS

BGXJW had no cardiac, hepatic, renal, or intestinal toxicity in mice. Alcoholic liver injury and steatosis in the NIAAA mode were effectively prevented by BGXJW treatment. BGXJW increased the expression of alcohol metabolizing enzymes ADH, CYP2E1, and ALDH2 to enhance alcohol metabolism, inhibited steatosis through regulating lipid metabolism, counteracted alcohol-induced upregulation of lipid synthesis related proteins SREBP1, FASN, and SCD1, meanwhile it enhanced fatty acids β-oxidation related proteins PPAR-α and CPT1A. Alcohol taken enhanced pro-inflammatory TNF-α, IL-6 and down-regulated the anti-inflammatory IL-10 expression in the liver, which were also reversed by BGXJW administration. Moreover, BGXJW significantly decreased the blood ethanol concentration and alleviated drunkenness in the alcohol binge-drinking mice model.

CONCLUSIONS

BGXJW could effectively relieve drunkenness and prevent alcoholic liver disease by regulating lipid metabolism, inflammatory response, and alcohol metabolism.

Structural characterization and anti-lipotoxicity effects of a pectin from okra (Abelmoschus esculentus (L.) Moench)

Okra (Abelmoschus esculentus (L.) Moench) is rich in various bioactive ingredients and used as a medicinal plant in traditional medicine. In the present study, to find the polysaccharide with anti-lipotoxicity effects from okra and clarify its structure, a pectin OP-1 was purified from okra, which had a backbone containing →4)-α-GalpA-(1 → residues, and 1,5-Ara linked the main chain through the O-3 of the residue →3,4)-α-GalpA-(1→, and the C-6 of residue 1, 4-α-GalpA replaced by methyl ester. In vitro experiments showed that OP-1 pretreatment alleviated oleic acid (OA)-induced lipid accumulation, ROS generation, apoptosis, transaminase leakage, and inflammatory cytokine secretion in HepG2 cells, resulting in reduced lipotoxicity. Further molecular results revealed that OP-1 increased Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) phosphorylation and affected the expression of AMPK downstream targets, including inhibit SREBP1c and FAS, as well as activate CPT-1A. Impressively, AMPK inhibitor dorsomorphin (Compound C) blocked the effects of OP-1 against lipotoxicity. The effects of OP-1 on lipid metabolism were also diminished by dorsomorphin. Our results demonstrated that OP-1 possesses a potent function in preventing lipotoxicity via regulating AMPK-mediated lipid metabolism and provide a novel insight into the future utilization of okra polysaccharide.

Taxifolin-3-O-glucoside from Osbeckia nepalensis Hook. mediates antihyperglycemic activity in CC1 hepatocytes and in diabetic Wistar rats via regulating AMPK/G6Pase/PEPCK signaling axis

ETHNOPHARMACOLOGICAL RELEVANCE

Osbeckia nepalensis Hook. f. is an ICMR documented plant well known for its antidiabetic uses among the folk people of Northeast Region of India. In-depth study with scientific substantiation of the plant may uphold the therapeutic potential against the treatment of type 2 diabetes mellitus (T2DM).

AIM OF THE STUDY

The present study evaluates the traditionally claimed prophylactic potential of O. nepalensis and its extracts along with the isolated compound taxifolin-3-O-glucoside (TG) against the downregulation of T2DM related hepatic gluconeogenesis through in vitro, in vivo and in silico conditions as a means of ameliorating hyperglycemia.

MATERIALS AND METHODS

Antidiabetic potential of O. nepalensis was carried out in both CC1 hepatocytes (in vitro) and STZ-induced diabetic male Wistar rats (in vivo). Enriched bioactive fraction and bioactive molecules were isolated through bioactivity-guided fractionation, yielding two major molecules, taxifolin-3-O-glucoside and quercitin-3-O-rhamnoside. The bioactivity of taxifolin-3-O-glucoside was validated through immunoblotting techniques aided by in silico molecular docking and simulations.

RESULTS

Methanolic extract of O. nepalensis and taxifolin-3-O-glucoside (TG) isolated thereof enhanced the uptake of glucose in CC1 hepatocytes and downregulates the gluconeogenic enzymes (G6Pase and PEPCK) and its related transcription factors (FOXO1, HNF4α and PGC1α) through the stimulation of AMPK phosphorylation in in vitro condition. Moreover, in in vivo experiments, the in vitro most active fraction BuSFr1 (consisting of the two active major compounds taxifolin-3-O-glucoside and quercitin-3-O-rhamnoside) exhibited a substantial decrease in elevated blood glucose level and increase the glucose tolerance as well as plasma insulin level. In silico molecular docking and simulations for TG with the protein G6Pase inferred the docking sites and stability and showed taxifolin-3-O-glucoside as more potent and non-toxic as compared to quercitin-3-O-rhamnoside.

CONCLUSION

The traditionally claimed antidiabetic effect of O. nepalensis has been proved to be effective in lowering the blood glucose level through in vitro, in vivo and in silico analysis which will pave a way for the development of antidiabetic phytopharmaceutical drugs which can be validated through further clinical studies.

Monounsaturated fatty acid-enriched olive oil exacerbates chronic alcohol-induced hepatic steatosis and liver injury in C57BL/6J mice

Dietary oil composition determines the pathological processes of alcoholic fatty liver disease (AFLD). Oil rich in saturated fatty acids protects, whereas oil rich in polyunsaturated fatty acids aggravates the alcohol-induced liver injury. However, limited studies have been conducted to address how monounsaturated fatty acids (MUFAs) enriched oil controls the pathological development of AFLD. Therefore, this study was designed to evaluate the effect of MUFA-enriched extra virgin olive oil (OO) on AFLD. Twenty C57BL/6J mice were randomly allocated into four groups and fed modified Lieber-DeCarli liquid diets containing isocaloric maltose dextrin a non-alcohol or alcohol with corn oil and OO for four weeks. Dietary OO significantly exacerbated alcohol-induced liver dysfunction, evidenced by histological examinations and disturbed biochemical parameters. Dietary OO with alcohol decreased hormone-sensitive lipase (HSL), phosphorylated 5'-AMP-activated protein kinase (p-AMPK), and carnitine palmitoyltransferase-Iα (CPT1α) expression, and increased sterol regulatory element-binding protein-1c (SREBP-1c), diacylglycerol acyltransferase-2 (DGAT2), and very low-density lipoprotein receptor (VLDLR) expression in the liver. It also promoted the expression of hepatic interleukin-6 (IL-6) and hepatic tumour necrosis factor-alpha (TNF-α) at the transcriptional level. Additionally, adipose tissue lipolysis partially had an etiologic effect on alcohol-induced hepatic steatosis under OO pretreatment. In conclusion, MUFA-enriched OO exacerbated liver dysfunction in vivo. OO should be cautiously considered as a unique dietary oil source for individuals with AFLD.

Xanthosine, a purine glycoside mediates hepatic glucose homeostasis through inhibition of gluconeogenesis and activation of glycogenesis via regulating the AMPK/ FoxO1/AKT/GSK3β signaling cascade

Type 2 Diabetes Mellitus (T2DM) is characterized by hepatic insulin resistance, which results in increased glucose production and reduced glycogen storage in the liver. There is no previous study in the literature that has explored the role of Xanthosine in hepatic insulin resistance. Moreover, mechanistic explanation for the beneficial effects of Xanthosine in lowering glucose production in diabetes is yet to be determined. This study for the first time investigated the beneficial effects of Tribulus terrestris (TT) and its active constituent, Xanthosine on gluconeogenesis and glycogenesis in Free Fatty Acid (FFA)-induced CC1 hepatocytes and streptozotocin (STZ)-induced Wistar rats. Xanthosine enhanced glucose uptake and decreased glucose production through phosphorylation of AMP-activated protein kinase (AMPK) and forkhead box transcription factor O1 (FoxO1), and downregulation of two rate limiting enzymes of gluconeogenesis, phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) expression in FFA-induced CC1 cells. Xanthosine also prevented FFA-induced decreases in the phosphorylation of AKT/Protein kinase B, glycogen synthase kinase-3β (GSK3β), and increased glycogen synthase (GS) phosphorylation to increase the glycogen content in the hepatocytes. Moreover, in STZ-induced diabetic rats, oral administration of TT n-butanol fraction (TTBF) enriched with compound Xanthosine (10, 50 & 100 mg/kg body weight) improved insulin sensitivity, reduced fasting blood glucose levels, improved glucose homeostasis by reducing gluconeogenesis via AMPK/FoxO1-mediated PEPCK and G6Pase down-regulation and increasing glycogenesis via AKT/GSK3β-mediated GS activation. Overall, Xanthosine may be developed further for treating insulin resistance and hyperglycemia in T2DM.

FAM3A maintains metabolic homeostasis by interacting with F1-ATP synthase to regulate the activity and assembly of ATP synthase

Reduced mitochondrial ATP synthase (ATPS) capacity plays crucial roles in the pathogenesis of metabolic disorders. However, there is currently no effective strategy for synchronously stimulating the expressions of ATPS key subunits to restore its assembly. This study determined the roles of mitochondrial protein FAM3A in regulating the activity and assembly of ATPS in hepatocytes. FAM3A is localized in mitochondrial matrix, where it interacts with F1-ATPS to initially activate ATP synthesis and release, and released ATP further activates P2 receptor-Akt-CREB pathway to induce FOXD3 expression. FOXD3 synchronously stimulates the transcriptions of ATPS key subunits and assembly genes to increase its assembly and capacity, augmenting ATP synthesis and inhibiting ROS production. FAM3A, FOXD3 and ATPS expressions were reduced in livers of diabetic mice and NAFLD patients. FOXD3 expression, ATPS capacity and ATP content were reduced in various tissues of FAM3A-deficient mice with dysregulated glucose and lipid metabolism. Hepatic FOXD3 activation increased ATPS assembly to ameliorate dysregulated glucose and lipid metabolism in obese mice. Hepatic FOXD3 inhibition or knockout reduced ATPS capacity to aggravate HFD-induced hyperglycemia and steatosis. In conclusion, FAM3A is an active ATPS component, and regulates its activity and assembly by activating FOXD3. Activating FAM3A-FOXD3 axis represents a viable strategy for restoring ATPS assembly to treat metabolic disorders.

Lambda-cyhalothrin induces lipid accumulation in mouse liver is associated with AMPK inactivation

Lambda-cyhalothrin (LCT) is a critical synthetic Type II pyrethroid insecticide widely applied. Several studies suggest pyrethroids could induce fat accumulation, promote adipogenesis, and impair liver function. Now, the influences of LCT on the hepatic lipid metabolism and the cellular mechanism is still unknown. AMPK has important function in regulating cellular energy balance. To indicate the potential pathogenesis of liver injury caused by LCT exposure, ICR mice were orally administrated with LCT at a dose of 0.4 mg/kg and 2 mg/kg. The results suggest that LCT induced obesity, dyslipidemia and hepatic steatosis. In addition, LCT also induced oxidative stress, liver function injury, and disorganized structure of the liver. Furthermore, upregulation of PPARγ, FASN, and SREBP1c expression, as well as reduction of PPARα and FGF21 expression, bringing with decreases of phosphorylated ratios of AMPK and ACC were found in LCT-L group. These results indicate that LCT at 0.4 mg/kg could result in dyslipidemia and hepatic steatosis in mice. In addition, activation of AMPK in hepatocytes effectively attenuated the effects of LCT. The detailed mechanism of LCT-induced hepatic steatosis is associated with AMPK and its downsteam genes. Activation of AMPK might be a novel protection against the progression of hepatic steatosis induced by LCT.

AMPK inhibits liver gluconeogenesis: fact or fiction?

Is there a role for AMPK in the control of hepatic gluconeogenesis and could targeting AMPK in liver be a viable strategy for treating type 2 diabetes? These are frequently asked questions this review tries to answer. After describing properties of AMPK and different small-molecule AMPK activators, we briefly review the various mechanisms for controlling hepatic glucose production, mainly via gluconeogenesis. The different experimental and genetic models that have been used to draw conclusions about the role of AMPK in the control of liver gluconeogenesis are critically discussed. The effects of several anti-diabetic drugs, particularly metformin, on hepatic gluconeogenesis are also considered. We conclude that the main effect of AMPK activation pertinent to the control of hepatic gluconeogenesis is to antagonize glucagon signalling in the short-term and, in the long-term, to improve insulin sensitivity by reducing hepatic lipid content.

Berberine Ameliorates Abnormal Lipid Metabolism via the Adenosine Monophosphate-Activated Protein Kinase/Sirtuin 1 Pathway in Alcohol-Related Liver Disease

Alcoholic fatty liver disease (AFLD) is an early stage of alcohol-related liver disease characterized by abnormal lipid metabolism in hepatocytes. To date, to our knowledge, there have been no effective strategies for preventing or treating alcohol-related liver disease besides alcohol abstinence. Berberine (BBR) is the main bioactive ingredient extracted from traditional Chinese medicines, such as Coptis and Scutellaria, which protect liver function and relieve liver steatosis. However, the potential role of BBR in AFLD remains unclear. Therefore, this study investigated the protective effects of BBR against Gao-binge model-induced AFLD in 6- to 8-week-old C57BL/6J male mice in vivo and ethyl alcohol (EtOH)-induced alpha mouse liver 12 (AML-12) cells in vitro. The results showed that BBR (200 mg/kg) attenuated alcoholic liver injury and suppressed lipid accumulation and metabolism disorders in vivo. Consistently, BBR effectively inhibited the expression of sterol regulatory element-binding transcription factor 1C, sterol regulatory element-binding transcription factor 2, fatty acid synthase, and 3-hydroxy-3-methylglutaryl-CoenzymeA reductase in EtOH-stimulated AML-12 cells in vitro and promoted the expression of sirtuin 1 (SIRT1) in EtOH-fed mice and EtOH-treated AML-12 cells. Furthermore, SIRT1 silencing attenuated the hepatic steatosis alleviation potential of BBR treatment. Mechanistically, molecular docking revealed the binding effect of BBR and adenosine monophosphate-activated protein kinase (AMPK). The results of further studies showed that a decrease in AMPK activity was accompanied by a significant inhibition of SIRT1 expression. SIRT1 silencing attenuated the protective effect of BBR, whereas the inhibition of its expression had no apparent effect on AMPK phosphorylation, suggesting that SIRT1 acts downstream of AMPK in AFLD. Collectively, BBR ameliorated abnormal lipid metabolism and alleviated EtOH-induced liver injury via the AMPK/SIRT1 pathway in AFLD mice.

Raphanus sativus L. var. caudatus Extract Alleviates Impairment of Lipid and Glucose Homeostasis in Liver of High-Fat Diet-Induced Obesity and Insulin Resistance in Mice

The present study investigated the activities of Raphanus sativus L. var. caudatus extract (RS) on abnormal lipid and glucose homeostasis in a high-fat diet (HFD)-induced obesity and insulin resistance in a mouse model. Institute of Cancer Research mice were rendered obese by 16-week HFD feeding. Obese mice were administered with 100 or 200 mg/kg/d RS orally during the last 8 weeks of diet feeding. Then, the biochemical parameters were determined. The gene and protein expressions regulating lipid and glucose homeostasis in the liver were measured. This study revealed that the state of hyperglycemia, hyperleptinemia, hyperinsulinemia, and hyperlipidemia was reduced after 8 weeks of RS treatment (100 or 200 mg/kg). Administration of RS also improved insulin sensitivity and increased serum adiponectin. The liver total cholesterol and triglyceride concentrations were decreased by both doses of RS. Notably, a decrease in the expression of liver-specific genes, including sterol regulatory element-binding protein 1c, fatty acid synthase, and acetyl-CoA carboxylase, was found in the RS-treated groups. Moreover, administration of RS showed a significant increase in the expression of adenosine monophosphate-activated protein kinase (AMPK) phosphorylation and sirtuin1 (Sirt1) proteins. These findings indicated that RS improved abnormal lipid and glucose homeostasis in the liver of obesity-associated insulin resistance mouse model, possibly through the stimulation of the AMPK/Sirt1 pathway.

Ellagic acid protects against non-alcoholic fatty liver disease in streptozotocin-diabetic rats by activating AMPK

CONTEXT

Ellagic acid (EA) is used in traditional medicine to treated hyperlipidaemia.

OBJECTIVE

This study examined if AMPK mediates the anti-steatotic effect of ellagic acid (EA) in streptozotocin (STZ)-induced type 1 diabetes mellitus in rats.

MATERIALS AND METHODS

Adult male Wistar rats (130 ± 10 g) were divided into 6 groups (n = 8 rats/group) as control, control + EA, control + EA + CC an AMPK inhibitor), T1DM, T1DM + EA, and T1DM + EA + CC. The treatments with EA (50 mg/kg/orally) and CC (200 ng/rat/i.p.) were given the desired groups for 12 weeks, daily.

RESULTS

In T1DM-rats, EA reduced fasting glucose levels (44.8%), increased fasting insulin levels (92.8%), prevented hepatic lipid accumulation, and decreased hepatic and serum levels of total triglycerides (54% & 61%), cholesterol (57% & 48%), and free fatty acids (40% & 37%). It also reduced hepatic levels of ROS (62%), MDA (52%), TNF-α (62%), and IL-6 (57.2%) and the nuclear activity of NF-κB p65 (54%) but increased the nuclear activity of Nrf-2 (4-fold) and levels of GSH (107%) and SOD (87%). Besides, EA reduced downregulated SREBP1 (35%), SREBP2 (34%), ACC-1 (36%), FAS (38%), and HMG-CoAR (49%) but stimulated mRNA levels of PPARα (1.7-fold) and CPT1a (1.8-fold), CPT1b (2.9-fold), and p-AMPK (4-fold). All these events were prevented by the co-administration of CC.

DISCUSSION AND CONCLUSIONS

These findings encourage the use of EA to treat hepatic disorders, and non-alcoholic fatty liver disease (NAFLD). Further in vivo and in vitro studies are needed to validate its potential in clinical medicine.

The Good, the Bad and the New about Uric Acid in Cancer

Simple Summary

The concentration of uric acid in blood is sex-, age- and diet-dependent and is maintained close to its maximal solubility, indicating that it plays some important role. Indeed, it has been demonstrated that, at physiological concentrations, uric acid is a powerful antioxidant and is a scavenger of singlet oxygen and radicals. At high intracellular concentration, uric acid has been demonstrated to act as a pro-oxidant molecule. Recently, uric acid has been reported to affect the properties of several proteins involved in metabolic regulation and signaling, and the relationship between uric acid and cancer has been extensively investigated. In this review, we present the most recent results on the positive and negative effects played by uric acid in cancer and some new findings and hypotheses about the implication of this metabolite in the pathogenesis of several diseases such as metabolic syndrome, diabetes, and inflammation, thus favoring the development of cancer.

Abstract

Uric acid is the final product of purine catabolism in man and apes. The serum concentration of uric acid is sex-, age- and diet-dependent and is maintained close to its maximal solubility, indicating that it plays some important role. Indeed, it has been demonstrated that, at physiological concentrations, uric acid is a powerful antioxidant, while at high intracellular concentrations, it is a pro-oxidant molecule. In this review, we describe the possible causes of uric acid accumulation or depletion and some of the metabolic and regulatory pathways it may impact. Particular attention has been given to fructose, which, because of the complex correlation between carbohydrate and nucleotide metabolism, causes uric acid accumulation. We also present recent results on the positive and negative effects played by uric acid in cancer and some new findings and hypotheses about the implication of this metabolite in a variety of signaling pathways, which can play a role in the pathogenesis of diseases such as metabolic syndrome, diabetes, and inflammation, thus favoring the development of cancer. The loss of uricase in Homo sapiens and great apes, although exposing these species to the potentially adverse effects of uric acid, appears to be associated with evolutionary advantages.

Ginsenosides Restore Lipid and Redox Homeostasis in Mice with Intrahepatic Cholestasis through SIRT1/AMPK Pathways

Intrahepatic cholestasis (IC) occurs when the liver and systemic circulation accumulate bile components, which can then lead to lipid metabolism disorders and oxidative damage. Ginsenosides (GS) are pharmacologically active plant products derived from ginseng that possesses lipid-regulation and antioxidation activities. The purpose of this study was to evaluate the possible protective effects of ginsenosides (GS) on lipid homeostasis disorder and oxidative stress in mice with alpha-naphthylisothiocyanate (ANIT)-induced IC and to investigate the underlying mechanisms. A comprehensive strategy via incorporating pharmacodynamics and molecular biology technology was adopted to investigate the therapeutic mechanisms of GS in ANIT-induced mice liver injury. The effects of GS on cholestasis were studied in mice that had been exposed to ANIT-induced cholestasis. The human HepG2 cell line was then used in vitro to investigate the molecular mechanisms by which GS might improve IC. The gene silencing experiment and liver-specific sirtuin-1 (SIRT1) knockout (SIRT1^LKO) mice were used to further elucidate the mechanisms. The general physical indicators were assessed, and biological samples were collected for serum biochemical indexes, lipid metabolism, and oxidative stress-related indicators. Quantitative PCR and H&E staining were used for molecular and pathological analysis. The altered expression levels of key pathway proteins (Sirt1, p-AMPK, Nrf2) were validated by Western blotting. By modulating the AMPK protein expression, GS decreased hepatic lipogenesis, and increased fatty acid β-oxidation and lipoprotein lipolysis, thereby improving lipid homeostasis in IC mice. Furthermore, GS reduced ANIT-triggered oxidative damage by enhancing Nrf2 and its downstream target levels. Notably, the protective results of GS were eliminated by SIRT1 shRNA in vitro and SIRT1^LKO mice in vivo. GS can restore the balance of the lipid metabolism and redox in the livers of ANIT-induced IC models via the SIRT1/AMPK signaling pathway, thus exerting a protective effect against ANIT-induced cholestatic liver injury.

Stress-Induced Premature Senescence Related to Oxidative Stress in the Developmental Programming of Nonalcoholic Fatty Liver Disease in a Rat Model of Intrauterine Growth Restriction

Metabolic syndrome (MetS) refers to cardiometabolic risk factors, such as visceral obesity, dyslipidemia, hyperglycemia/insulin resistance, arterial hypertension and non-alcoholic fatty liver disease (NAFLD). Individuals born after intrauterine growth restriction (IUGR) are particularly at risk of developing metabolic/hepatic disorders later in life. Oxidative stress and cellular senescence have been associated with MetS and are observed in infants born following IUGR. However, whether these mechanisms could be particularly associated with the development of NAFLD in these individuals is still unknown. IUGR was induced in rats by a maternal low-protein diet during gestation versus. a control (CTRL) diet. In six-month-old offspring, we observed an increased visceral fat mass, glucose intolerance, and hepatic alterations (increased transaminase levels, triglyceride and neutral lipid deposit) in male rats with induced IUGR compared with the CTRL males; no differences were found in females. In IUGR male livers, we identified some markers of stress-induced premature senescence (SIPS) (lipofuscin deposit, increased protein expression of p21WAF, p16INK4a and Acp53, but decreased pRb/Rb ratio, foxo-1 and sirtuin-1 protein and mRNA expression) associated with oxidative stress (higher superoxide anion levels, DNA damages, decreased Cu/Zn SOD, increased catalase protein expression, increased nfe2 and decreased keap1 mRNA expression). Impaired lipogenesis pathways (decreased pAMPK/AMPK ratio, increased pAKT/AKT ratio, SREBP1 and PPARγ protein expression) were also observed in IUGR male livers. At birth, no differences were observed in liver histology, markers of SIPS and oxidative stress between CTRL and IUGR males. These data demonstrate that the livers of IUGR males at adulthood display SIPS and impaired liver structure and function related to oxidative stress and allow the identification of specific therapeutic strategies to limit or prevent adverse consequences of IUGR, particularly metabolic and hepatic disorders.

Molecular Changes in Relation to Alcohol Consumption and Hepatocellular Carcinoma

Alcohol is the one of the major causes of liver diseases and promotes liver cirrhosis and hepatocellular carcinoma (HCC). In hepatocytes, alcohol is converted to acetaldehyde, which causes hepatic steatosis, cellular apoptosis, endoplasmic reticulum stress, peroxidation, production of cytokines and reduces immune surveillance. Endotoxin and lipopolysaccharide produced from intestinal bacteria also enhance the production of cytokines. The development of hepatic fibrosis and the occurrence of HCC are induced by these alcohol metabolites. Several host genetic factors have recently been identified in this process. Here, we reviewed the molecular mechanism associated with HCC in alcoholic liver disease.

Salvia-Nelumbinis naturalis improves lipid metabolism of NAFLD by regulating the SIRT1/AMPK signaling pathway

Background

Salvia-Nelumbinis naturalis (SNN), the extract of Chinese herbal medicine, has shown effects on NAFLD. This study aims to explore the underlying mechanism of SNN for regulating the lipid metabolism disorder in NAFLD based on the SIRT1/AMPK signaling pathway.

Methods

Male C57BL/6J mice fed with a high-fat diet (HFD) were used to establish the NAFLD model. Dynamic changes of mice including body weight, liver weight, serological biochemical indexes, liver histopathological changes, and protein level of AMPK and SIRT1 were monitored. After18 weeks, SNN treatment was administrated to the NAFLD mice for another 4 weeks. Besides the aforementioned indices, TC and TG of liver tissues were also measured. Western blot and quantitative RT-PCR were used to detect the expression and/or activation of SIRT1 and AMPK, as well as the molecules associated with lipid synthesis and β-oxidation. Furthermore, AML12 cells with lipid accumulation induced by fatty acids were treated with LZG and EX527 (SIRT1 inhibitor) or Compound C (AMPK inhibitor ) to confirm the potential pharmacological mechanism.

Results

Dynamic observation found the mice induced by HFD with gradually increased body and liver weight, elevated serum cholesterol, hepatic lipid accumulation, and liver injury. After 16 weeks, these indicators have shown obvious changes. Additionally, the hepatic level of SIRT1 and AMPK activation was identified gradually decreased with NAFLD progress. The mice with SNN administration had lower body weight, liver weight, and serum level of LDL-c and ALT than those of the NAFLD model. Hepatosteatosis and hepatic TG content in the liver tissues of the SNN group were significantly reduced. When compared with control mice, the NAFLD mice had significantly decreased hepatic expression of SIRT1, p-AMPK, p-ACC, ACOX1, and increased total Acetylated-lysine, SUV39H2, and SREBP-1c. The administration of SNN reversed the expression of these molecules. In vitro experiments showed the effect of SNN in ameliorating hepatosteatosis and regulating the expression of lipid metabolism-related genes in AML12 cells, which were diminished by EX527 or Compound C co-incubation.

Conclusions

Taken together, the SIRT1/AMPK signaling pathway, involved in hepatic lipid synthesis and degradation, plays a pivotal role in the pathogenesis of NAFLD development. The regulation of SIRT1/AMPK signaling greatly contributes to the underlying therapeutic mechanism of SNN for NAFLD.

Metformin enhances LDL-cholesterol uptake by suppressing the expression of the pro-protein convertase subtilisin/kexin type 9 (PCSK9) in liver cells

PURPOSE

Metformin (MF) intake associates with reduced levels of circulating low-density lipoprotein-cholesterol (LDL-C). This has been attributed to the activation of AMPK, which differentially regulates the expression of multiple genes involved in cholesterol synthesis and trafficking. However, the exact mechanism underlying the LDL-C lowering effect of MF remains ambiguous.

METHODS

MF-treated Hep-G2 and HuH7 cells were evaluated for cell viability and the expression status of key lipid metabolism-related genes along with LDL-C uptake efficiency.

RESULTS

MF treatment resulted in decreased expression and secretion of PCSK9, increased expression of LDLR and enhanced LDL-C uptake in hepatocytes. It also resulted in increased expression of activated AMPK (p-AMPK) and decreased expression of SREBP2 and HNF-1α proteins. Transcriptomic analysis of MF-treated Hep-G2 cells confirmed these findings and showed that other key lipid metabolism-related genes including those that encode apolipoproteins (APOB, APOC2, APOC3 and APOE), MTTP and LIPC are downregulated. Lastly, MF treatment associated with reduced HMG-CoA reductase expression and activity.

CONCLUSIONS

These findings suggest that MF treatment reduces circulating LDL-C levels by suppressing PCSK9 expression and enhancing LDLR expression; hence the potential therapeutic utility of MF in hypercholesterolemia.

Upregulation of 4-Hydroxynonenal Contributes to the Negative Effect of n-6 Polyunsaturated Fatty Acid on Alcohol-Induced Liver Injury and Hepatic Steatosis

The present study aimed to investigate the effects of saturated fatty acids (SFA) and n-6 polyunsaturated fatty acids (PUFA) on alcoholic liver disease (ALD) and the underlying mechanisms. C57BL/6J male mice were randomly fed a corn oil or palm oil diet (rich in n-6 PUFA and SFA, respectively) with or without ethanol for four weeks (n = 10/group). A series of experiments in vitro with AML-12 hepatocyte were conducted to better elucidate the potential mechanisms underlying the phenomenon observed in animals. Compared with palm oil, corn oil aggravated alcohol-induced liver injury and hepatic steatosis, indicated by a histological analysis and significant elevations of plasma alanine aminotransferase and hepatic triacylglycerol (TG) level. Apoptosis-associated proteins in the ASK1-JNK pathway were significantly enhanced in the liver of mice from the corn oil + ethanol group than in the palm oil + ethanol group. The corn oil + ethanol diet also inhibited the activation of both AMPK and downstream protein acetyl-CoA carboxylase (ACC) and promoted the SREBP-1c expression, subsequently accelerating lipid synthesis. In addition, 4-hydroxynonenal (4-HNE) levels in plasma and liver were significantly upregulated in response to corn oil + ethanol feeding. Interestingly, the in vitro study showed that 4-HNE significantly attenuated cell viability, elevated the expression of cleaved-caspase 3 protein and TG level, and regulated key molecules in ASK1-JNK and AMPK pathways in a dose-dependent manner. In conclusion, the n-6 PUFA diet showed a negative effect on alcohol-induced liver injury and steatosis. It might be related to the upregulation of 4-HNE and subsequent changes of proteins, namely, ASK1, JNK, AMPK, ACC, and SREBP-1c.

Natural products: Potential therapeutic agents to prevent skeletal muscle atrophy

The skeletal muscle (SkM) is the largest organ, which plays a vital role in controlling musculature, locomotion, body heat regulation, physical strength, and metabolism of the body. A sedentary lifestyle, aging, cachexia, denervation, immobilization, etc. Can lead to an imbalance between protein synthesis and degradation, which is further responsible for SkM atrophy (SmA). To date, the understanding of the mechanism of SkM mass loss is limited which also restricted the number of drugs to treat SmA. Thus, there is an urgent need to develop novel approaches to regulate muscle homeostasis. Presently, some natural products attained immense attraction to regulate SkM homeostasis. The natural products, i.e., polyphenols (resveratrol, curcumin), terpenoids (ursolic acid, tanshinone IIA, celastrol), flavonoids, alkaloids (tomatidine, magnoflorine), vitamin D, etc. exhibit strong potential against SmA. Some of these natural products have been reported to have equivalent potential to standard treatments to prevent body lean mass loss. Indeed, owing to the large complexity, diversity, and slow absorption rate of bioactive compounds made their usage quite challenging. Moreover, the use of natural products is controversial due to their partially known or elusive mechanism of action. Therefore, the present review summarizes various experimental and clinical evidence of some important bioactive compounds that shall help in the development of novel strategies to counteract SmA elicited by various causes.

Synergistic effect of antimetabolic and chemotherapy drugs in triple-negative breast cancer

The triple-negative breast cancer (TNBC) subtype comprises approximately 15% of all breast cancers and is associated with poor long-term outcomes. Classical chemotherapy remains the standard of treatment, with toxicity and resistance being major limitations. TNBC is a high metabolic group, and antimetabolic drugs are effective in inhibiting TNBC cell growth. We analyzed the combined effect of chemotherapy and antimetabolic drug combinations in MDA-MB-231, MDA-MB-468 and HCC1143 human TNBC cell lines. Cells were treated with each drug or with drug combinations at a range of concentrations to establish the half-maximal inhibitory concentrations (IC₅₀). The dose-effects of each drug or drug combination were calculated, and the synergistic or antagonistic effects of drug combinations were defined. Chemotherapy and antimetabolic drugs exhibited growth inhibitory effects on TNBC cell lines. Antimetabolic drugs targeting the glycolysis pathway had a synergistic effect with chemotherapy drugs, and antiglycolysis drug combinations also had a synergistic effect. The use of these drug combinations could lead to new therapeutic strategies that reduce chemotherapy drug doses, decreasing their toxic effect, or that maintain the doses but enhance their efficacy by their synergistic effect with other drugs.

Potential Roles and Key Mechanisms of Hawthorn Extract against Various Liver Diseases

The genus Crataegus (hawthorn), a flowering shrub or tree, is a member of the Rosaceae family and consists of approximately 280 species that have been primarily cultivated in East Asia, North America, and Europe. Consumption of hawthorn preparations has been chiefly associated with pharmacological benefits for cardiovascular diseases, including congestive heart failure and angina pectoris. Treatment with hawthorn extracts can be related to improvements in the complex pathogenesis of various hepatic and cardiovascular disorders. In this regard, the present review described that the presence of hawthorn extracts ameliorated hepatic injury, lipid accumulation, inflammation, fibrosis, and cancer in an abundance of experimental models. Hawthorn extracts might have these promising activities, largely by enhancing the hepatic antioxidant system. In addition, several mechanisms, including AMP-activated protein kinase (AMPK) signaling and apoptosis, are responsible for the role of hawthorn extracts in repairing the dysfunction of injured hepatocytes. Specifically, hawthorn possesses a wide range of biological actions relevant to the treatment of toxic hepatitis, alcoholic liver disease, non-alcoholic fatty liver disease, and hepatocellular carcinoma. Accordingly, hawthorn extracts can be developed as a major source of therapeutic agents for liver diseases.

Metformin and Insulin Resistance: A Review of the Underlying Mechanisms behind Changes in GLUT4-Mediated Glucose Transport

Metformin is the most commonly used treatment to increase insulin sensitivity in insulin-resistant (IR) conditions such as diabetes, prediabetes, polycystic ovary syndrome, and obesity. There is a well-documented correlation between glucose transporter 4 (GLUT4) expression and the level of IR. Therefore, the observed increase in peripheral glucose utilization after metformin treatment most likely comes from the induction of GLUT4 expression and its increased translocation to the plasma membrane. However, the mechanisms behind this effect and the critical metformin targets are still largely undefined. The present review explores the evidence for the crucial role of changes in the expression and activation of insulin signaling pathway mediators, AMPK, several GLUT4 translocation mediators, and the effect of posttranscriptional modifications based on previously published preclinical and clinical models of metformin’s mode of action in animal and human studies. Our aim is to provide a comprehensive review of the studies in this field in order to shed some light on the complex interactions between metformin action, GLUT4 expression, GLUT4 translocation, and the observed increase in peripheral insulin sensitivity.

Procyanidins from Hawthorn (Crataegus Pinnatifida) Alleviates Lipid Metabolism Disorder via Inhibiting Insulin Resistance and Oxidative Stress, Normalizing Gut Microbiota Structure and Intestinal Barrier, Further Suppressing Hepatic Inflammation and Lipid Accumulation

Recently, lipid metabolism disorder (LMD) has been regarded as a risky factor leading to multiple diseases and affecting human health. Procyanidins have been reported to be the potential therapy for...

Modulation of Insulin Resistance, Dyslipidemia and Serum Metabolome in iNOS Knockout Mice following Treatment with Nitrite, Metformin, Pioglitazone, and a Combination of Ampicillin and Neomycin

Oxidative and nitrosative stress plays a pivotal role in the incidence of metabolic disorders. Studies from this lab and others in iNOS-/- mice have demonstrated occurrence of insulin resistance (IR), hyperglycemia and dyslipidemia highlighting the importance of optimal redox balance. The present study evaluates role of nitrite, L-arginine, antidiabetics (metformin, pioglitazone) and antibiotics (ampicillin-neomycin combination, metronidazole) on metabolic perturbations observed in iNOS-/- mice. The animals were monitored for glucose tolerance (IPGTT), IR (insulin, HOMA-IR, QUICKI), circulating lipids and serum metabolomics (LC-MS). Hyperglycemia, hyperinsulinemia and IR were rescued by nitrite, antidiabetics, and antibiotics treatments in iNOS-/- mice. Glucose intolerance was improved with nitrite, metformin and pioglitazone treatment, while ampicillin-neomycin combination normalised the glucose utilization in iNOS-/- mice. Increased serum phosphatidylethanolamine lipids in iNOS-/- mice were reversed by metformin, pioglitazone and ampicillin-neomycin; dyslipidemia was however marginally improved by nitrite treatment. The metabolic improvements were associated with changes in selected serum metabolites-purines, ceramide, 10-hydroxydecanoate, glucosaminate, diosmetin, sebacic acid, 3-nitrotyrosine and cysteamine. Bacterial metabolites-hippurate, indole-3-ethanol; IR marker-aminoadipate and oxidative stress marker-ophthalmate were reduced by pioglitazone and ampicillin-neomycin, but not by nitrite and metformin treatment. Results obtained in the present study suggest a crucial role of gut microbiota in the metabolic perturbations observed in iNOS-/- mice.

Coping with extremes: High-altitude sparrows enhance metabolic and thermogenic capacities in the pectoralis muscle and suppress in the liver relative to their lowland counterparts

Animals living at high altitudes are challenged by the extreme environmental conditions of cold temperature and hypobaric hypoxia. It is not well understood how high-altitude birds enhance the capacity of metabolic thermogenesis and allocate metabolic capacity in different organs to maximize survival in extreme conditions of a cold winter. The Qinghai-Tibet Plateau (QTP) is the largest and highest plateau globally, offering a natural laboratory for investigating coping mechanisms of organisms inhabiting extreme environments. To understand the adaptive strategies in the morphology and physiology of small songbirds on the QTP, we compared plasma triiodothyronine (T₃), pectoralis muscle mitochondrial cytochrome c oxidase (COX) and state IV capacities, the expression of peroxisome proliferator-activated receptor γ coactivator α (PGC-1α), adenine nucleotide translocase (ANT), uncoupling protein (UCP), and adenosine monophosphate-dependent kinase (AMPK) α1 mRNA in the pectoralis and liver of Eurasian tree sparrows (Passer montanus) from high-altitude (3,230 m), medium-altitude (1400 m), and low-altitude (80 m) regions. Our results showed that high-altitude sparrows had greater body masses, longer wings and tarsometatarsi, but comparable bill lengths relative to medium- and low-altitude individuals. High-altitude sparrows had higher plasma T₃ levels and pectoralis muscle mitochondrial COX capacities than their lowland counterparts. They also upregulated the pectoralis muscle mRNA expression of UCP, PGC-1α, and ANT proteins relative to low-altitude sparrows. Unlike pectoralis, high-altitude sparrows significantly down-regulated hepatic AMPKα1 and ANT protein expression as compared with their lowland counterparts. Our results contribute to understanding the morphological, biochemical, and molecular adaptations in free-living birds to cope with the cold seasons in the extreme environment of the QTP.