Activation of AMPK by berberine induces hepatic lipid accumulation by upregulation of fatty acid translocase CD36 in mice

Microcystin-RR promote lipid accumulation through CD36 mediated signal pathway and fatty acid uptake in HepG2 cells

Microcystins (MC)-RR is a significant analogue of MC-LR, which has been identified as a hepatotoxin capable of influencing lipid metabolism and promoting the progression of liver-related metabolic diseases. However, the toxicity and biological function of MC-RR are still not well understood. In this study, the toxic effects and its role in lipid metabolism of MC-RR were investigated in hepatoblastoma cells (HepG2cells). The results demonstrated that MC-RR dose-dependently reduced cell viability and induced apoptosis. Additionally, even at low concentrations, MC-RR promoted lipid accumulation through up-regulating levels of triglyceride, total cholesterol, phosphatidylcholines and phosphatidylethaolamine in HepG2 cells, with no impact on cell viability. Proteomics and transcriptomics analysis further revealed significant alterations in the protein and gene expression profiles in HepG2 cells treated with MC-RR. Bioinformatic analysis, along with subsequent validation, indicated the upregulation of CD36 and activation of the AMPK and PI3K/AKT/mTOR in response to MC-RR exposure. Finally, knockdown of CD36 markedly ameliorated MC-RR-induced lipid accumulation in HepG2 cells. These findings collectively suggest that MC-RR promotes lipid accumulation in HepG2 cells through CD36-mediated signal pathway and fatty acid uptake. Our findings provide new insights into the hepatotoxic mechanism of MC-RR.

Berberine Effects in Pre-Fibrotic Stages of Non-Alcoholic Fatty Liver Disease-Clinical and Pre-Clinical Overview and Systematic Review of the Literature

Non-alcoholic fatty liver disease (NAFLD) is the predominant cause of chronic liver conditions, and its progression is marked by evolution to non-alcoholic steatosis, steatohepatitis, cirrhosis related to non-alcoholic steatohepatitis, and the potential occurrence of hepatocellular carcinoma. In our systematic review, we searched two databases, Medline (via Pubmed Central) and Scopus, from inception to 5 February 2024, and included 73 types of research (nine clinical studies and 64 pre-clinical studies) from 2854 published papers. Our extensive research highlights the impact of Berberine on NAFLD pathophysiology mechanisms, such as Adenosine Monophosphate-Activated Protein Kinase (AMPK), gut dysbiosis, peroxisome proliferator-activated receptor (PPAR), Sirtuins, and inflammasome. Studies involving human subjects showed a measurable reduction of liver fat in addition to improved profiles of serum lipids and hepatic enzymes. While current drugs for NAFLD treatment are either scarce or still in development or launch phases, Berberine presents a promising profile. However, improvements in its formulation are necessary to enhance the bioavailability of this natural substance.

Identification of potential pathogenic hepatic super-enhancers regulatory network in high-fat diet induced hyperlipidemia

Hyperlipidemia (HLP) is a prevalent metabolic disorder and a significant risk factor for cardiovascular disease. According to recent discoveries, super-enhancers (SEs) play a role in the increased expression of genes that encode important regulators of both cellular identity and the progression of diseases. However, the underlying function of SEs in the development of HLP is still unknown. We performed an integrative analysis of data on H3K27ac ChIP-seq and RNA sequencing obtained from liver tissues of mice under a low-fat diet (LFD) and high-fat diet (HFD) from GEO database. The rank ordering of super enhancers algorithm was employed for the computation and identification of SEs. A total of 1,877 and 1,847 SEs were identified in the LFD and HFD groups, respectively. The SE inhibitor JQ1 was able to potently reverse lipid deposition and the increased intracellular triglyceride and total cholesterol induced by oleic acid, indicating that SEs are involved in regulating lipid accumulation. Two hundred seventy-eight were considered as HFD-specific SEs (HSEs). GO and KEGG pathway enrichment analysis of the upregulated HSEs-associated genes revealed that they were mainly involved in lipid metabolic pathway. Four hub genes, namely Cd36, Pex11a, Ech1, and Cidec, were identified in the HSEs-associated protein-protein interaction network, and validated with two other datasets. Finally, we constructed a HSEs-specific regulatory network with Cidec and Cd36 as the core through the prediction and verification of transcription factors. Our study constructed a HSEs-associated regulatory network in the pathogenesis of HLP, providing new ideas for the underlying mechanisms and therapeutic targets of HLP.

Natural polysaccharides protect against diet-induced obesity by improving lipid metabolism and regulating the immune system

Unhealthy dietary patterns-induced obesity and obesity-related complications pose a great threat to human health all over the world. Accumulating evidence suggests that the pathophysiology of obesity and obesity-associated metabolic disorders is closely associated with dysregulation of lipid and energy metabolism, and metabolic inflammation. In this review, three potential anti-obesity mechanisms of natural polysaccharides are introduced. Firstly, natural polysaccharides protect against diet-induced obesity directly by improving lipid and cholesterol metabolism. Since the immunity also affects lipid and energy metabolism, natural polysaccharides improve lipid and energy metabolism by regulating host immunity. Moreover, diet-induced mitochondrial dysfunction, prolonged endoplasmic reticulum stress, defective autophagy and microbial dysbiosis can disrupt lipid and/or energy metabolism in a direct and/or inflammation-induced manner. Therefore, natural polysaccharides also improve lipid and energy metabolism and suppress inflammation by alleviating mitochondrial dysfunction and endoplasmic reticulum stress, promoting autophagy and regulating gut microbiota composition. Specifically, this review comprehensively summarizes underlying anti-obesity mechanisms of natural polysaccharides and provides a theoretical basis for the development of functional foods. For the first time, this review elucidates anti-obesity mechanisms of natural polysaccharides from the perspectives of their hypolipidemic, energy-regulating and immune-regulating mechanisms.

Peripheral Mitochondrial Dysfunction: A Potential Contributor to the Development of Metabolic Disorders and Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by loss of function and eventual death of neurons in the brain. Multiple studies have highlighted the involvement of mitochondria in the initiation and advancement of neurodegenerative diseases. Mitochondria are essential for ATP generation, bioenergetics processes, the regulation of calcium homeostasis and free radical scavenging. Disrupting any of these processes has been acknowledged as a major contributor to the pathogenesis of common neurodegenerative diseases, especially AD. Several longitudinal studies have demonstrated type 2 diabetes (T2D) as a risk factor for the origin of dementia leading towards AD. Even though emerging research indicates that anti-diabetic intervention is a promising option for AD prevention and therapy, results from clinical trials with anti-diabetic agents have not been effective in AD. Interestingly, defective mitochondrial function has also been reported to contribute towards the onset of metabolic disorders including obesity and T2D. The most prevalent consequences of mitochondrial dysfunction include the generation of inflammatory molecules and reactive oxygen species (ROS), which promote the onset and development of metabolic impairment and neurodegenerative diseases. Current evidence indicates an association of impaired peripheral mitochondrial function with primary AD pathology; however, the mechanisms are still unknown. Therefore, in this review, we discuss if mitochondrial dysfunction-mediated metabolic disorders have a potential connection with AD development, then would addressing peripheral mitochondrial dysfunction have better therapeutic outcomes in preventing metabolic disorder-associated AD pathologies.

Roles of protein post-translational modifications in glucose and lipid metabolism: mechanisms and perspectives

The metabolism of glucose and lipids is essential for energy production in the body, and dysregulation of the metabolic pathways of these molecules is implicated in various acute and chronic diseases, such as type 2 diabetes, Alzheimer's disease, atherosclerosis (AS), obesity, tumor, and sepsis. Post-translational modifications (PTMs) of proteins, which involve the addition or removal of covalent functional groups, play a crucial role in regulating protein structure, localization function, and activity. Common PTMs include phosphorylation, acetylation, ubiquitination, methylation, and glycosylation. Emerging evidence indicates that PTMs are significant in modulating glucose and lipid metabolism by modifying key enzymes or proteins. In this review, we summarize the current understanding of the role and regulatory mechanisms of PTMs in glucose and lipid metabolism, with a focus on their involvement in disease progression associated with aberrant metabolism. Furthermore, we discuss the future prospects of PTMs, highlighting their potential for gaining deeper insights into glucose and lipid metabolism and related diseases.

2,3,7,8-Tetrachlorodibenzo-p-dioxin induces liver lipid metabolism disorder via the ROS/AMPK/CD36 signaling pathway

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is widely considered as the most toxic and common carcinogen in the world. Exposure to TCDD causes liver lipid metabolism disorder and steatosis. However, the molecular mechanism of TCDD-induced liver lipid accumulation is not completely clear. Here, we found that a 5 μg/kg TCDD exposure for 3 weeks induced hepatocyte lipid deposition, increased CD36 expression, and promoted AMP-activated protein kinase (AMPK) ɑ phosphorylation in the liver of C57BL/6J mice. Furthermore, sulfo-N-succinimidyl oleate, a CD36 inhibiter, blunted TCDD-induced lipid deposition in Huh7 cells, confirming the critical role of CD36 in TCDD-induced hepatic steatosis. In terms of molecular mechanisms, we found that TCDD exposure increased reactive oxygen species (ROS) levels in Huh7 cells, which activated AMPK. Moreover, the activated AMPK upregulated CD36 expression. Therefore, we can see that the increase in CD36 expression induced by TCDD was regulated by ROS/AMPK/CD36 signaling pathway. Our results help to clarify the molecular mechanism of TCDD-induced hepatic steatosis.

Advances of berberine against metabolic syndrome-associated kidney disease: Regarding effect and mechanism

The prevalence of metabolic syndrome (MetS) is drastically growing worldwide, resulting in MetS-associated kidney disease. According to traditional theories, preventing blood pressure, lipid, glycose, and obesity and improving insulin resistance (IR), a couple of medications are required for MetS. It not only lowers patients' compliance but also elevates adverse reactions. Accordingly, we attempted to seek answers from complementary and alternative medicine. Ultimately, berberine (BBR) was chosen due to its efficacy and safety on MetS through multi-pathways and multi-targets. The effects and mechanisms of BBR on obesity, IR, diabetic nephropathy, hypertension, hyperlipidemia, and hyperuricemia were elaborated. In addition, the overall properties of BBR and interventions for various kidney diseases were also collected. However, more clinical trials are expected to further identify the beneficial effects of BBR.

Novel insights into the mediating roles of cluster of differentiation 36 in transmembrane transport and tissue partition of per- and polyfluoroalkyl substances in mice

Transmembrane transport is important for bioaccumulation of per- and polyfluoroalkyl substances (PFASs) in organisms, but has not yet been well understood. Here, the roles of cluster of differentiation 36 (CD36) in accumulation of PFASs were investigated. CD36 was overexpressed in Escherichia coli to get CD36-BL21 strain, and the binding affinities of 20 PFASs with CD36 were determined by microscale thermophoresis, which grew up to 17.5 μM with increasing carbon chain length. Consequently, the accumulation of most PFASs was remarkably promoted in CD36-BL21 in comparison to the wild strain, and the enhancement was proportional to their binding affinities with CD36 (r = -0.96). However, this effect was depressed greatly as CD36 was inhibited by sulfo-N-succinimidyl oleate (SSO). Additionally, as the mice received SSO pretreatment before they were exposed to perfluorododecanoic acid, its accumulation in the tissues rich in CD36, such as liver, was suppressed, but increased by 1.1 times in the serum. These indicated that CD36 played critical roles in the transmembrane transport and tissue partition of PFASs in organisms. The developed relationship between liver-blood partition of PFASs and their binding affinities with intracellular proteins was distinctly improved by incorporating that with CD36 (r = -0.97).

AMPK regulates behavior and physiological plasticity of Haliotis discus hannai under different spectral compositions

In natural environments, the spectral composition of incident light is often subject to drastic changes due to the abundance of suspended particles, floating animals, and plants in coastal waters. In this study, after four months of culturing under blue light (NB), orange light (NY), dark environment (ND), and natural light (NN), the shell length and weight-specific growth rate in Pacific abalone, Haliotis discus hannai, were ranked in the following order: NY > NN > ND > NB. To understand the growth differences in abalone under these different light environments, we first performed 24-h video monitoring and found that the cumulative movement distance and duration were lowest in group NB, whereas the cumulative movement distance and duration were significantly higher in group ND than in any other group (P < 0.05). In group NB, the time spent hidden underneath the attachment substrate accounted for 81% of the resting time, but this ratio was lowest in group ND, at only 37% (P < 0.05). Next, LC-MS metabolomics identified 201 and 105 metabolites in NB vs. NN, ND vs. NN, and NY vs. NN under the positive and negative ion modes, respectively. According to the fold changes and annotations for differential metabolites in the KEGG enrichment pathways, adenosine, NAD⁺, cGMP, and arachidonic acid were used as differential metabolism markers, and the AMPK signaling pathway was enriched in every comparison group, and thus investigated further. The gene sequences of three subtypes of AMPK were obtained by cloning and we found that the expression levels of AMPKα and AMPKγ, and the AMP content were significantly higher in group NB than in any other group (P < 0.05). In addition, the ATP contents and adenylate energy charge values were ranked in the following order: NY > NN > ND > NB. According to in situ hybridization analysis, the three subtype genes were widely expressed in the hepatopancreas. Finally, the contents of many lipid metabolites differed significantly among groups and the expression levels of the triglyceride hydrolysis-related gene hormone sensitive lipase and fatty acid oxidation-related gene carnitine palmitoyltransferase 1 were higher in groups ND and NB than in groups NN and NY according to fluorescence quantification PCR (P < 0.05). The expression levels of fatty acid synthase and acetyl-CoA carboxylase were significantly lower in groups ND and NB than in groups NN and NY (P < 0.05). These findings indicated that differences in the spectral composition of incident light could reshape the behavior and physiological metabolism in abalone by influencing the "energy switch" AMPK, thereby providing some insights into the mechanisms that allow nocturnal marine organisms to adapt to different lighting environments.

Molecular Mechanism of Lipotoxicity as an Interesting Aspect in the Development of Pathological States-Current View of Knowledge

Free fatty acids (FFAs) play numerous vital roles in the organism, such as contribution to energy generation and reserve, serving as an essential component of the cell membrane, or as ligands for nuclear receptors. However, the disturbance in fatty acid homeostasis, such as inefficient metabolism or intensified release from the site of storage, may result in increased serum FFA levels and eventually result in ectopic fat deposition, which is unfavorable for the organism. The cells are adjusted for the accumulation of FFA to a limited extent and so prolonged exposure to elevated FFA levels results in deleterious effects referred to as lipotoxicity. Lipotoxicity contributes to the development of diseases such as insulin resistance, diabetes, cardiovascular diseases, metabolic syndrome, and inflammation. The nonobvious organs recognized as the main lipotoxic goal of action are the pancreas, liver, skeletal muscles, cardiac muscle, and kidneys. However, lipotoxic effects to a significant extent are not organ-specific but affect fundamental cellular processes occurring in most cells. Therefore, the wider perception of cellular lipotoxic mechanisms and their interrelation may be beneficial for a better understanding of various diseases’ pathogenesis and seeking new pharmacological treatment approaches.

Sulfated Polysaccharides from Enteromorpha prolifera Attenuate Lipid Metabolism Disorders in Mice with High-fat Diet-induced Obesity via an AMPK-dependent Pathway

BACKGROUND

Obesity-related metabolic diseases have recently evoked worldwide attention. Studies have demonstrated that Enteromorpha polysaccharide (EP) exerts lipid-lowering effects, but the underlying mechanism remains unclear.

OBJECTIVE

To investigate whether EP regulates lipid metabolism disorders in mice with high-fat diet (HFD)-induced obesity via an AMP-activated protein kinase (AMPK)-dependent pathway.

METHODS

Six-week-old male C57BL/6J mice (18 ± 2 g) were fed a normal diet (ND; 10% energy from fats) or a HFD (60% energy from fats) for 6 weeks to induce obesity and treated intragastrically with EP (200 mg/kg body weight) or distilled water (10 mL/kg body weight) for 8 weeks. Biochemical indicators, AMPK-dependent pathways and lipid metabolism-related genes were evaluated to assess the effects of EP on HFD-induced lipid metabolism disorders. The essential role of AMPK in the EP-mediated regulation of lipid metabolism was confirmed using HFD-fed male Ampka2-knockout mice (aged 6 weeks, 17 ± 2 g) treated or not treated with the above-mentioned dose of EP. The data were analyzed by t tests and two-factor and one-way ANOVAs.

RESULTS

Compared to the ND, the HFD resulted in the greater body weight (24.3%), perirenal fat index (2.2-fold), and serum TC (24.66%) and LDL cholesterol (1.25-fold) concentrations (P < 0.05) and dysregulated the AMPK-dependent pathway and the expression of most lipid metabolism-related genes (P < 0.05). Compared to the HFD, EP treatment resulted in the lower perirenal fat index (31.22%) and the LDL-C concentration (23.98%) and partly reversed the dysregulation of the AMPK-dependent pathway and the altered expression of lipid metabolism-related genes (P < 0.05). Ampka2 knockout abolished the above-mentioned effects of EP in obese mice and the EP-mediated effects on the expression of lipid metabolism-related genes (P > 0.05).

CONCLUSIONS

These findings suggest that EP can ameliorate lipid metabolism disorders in mice with HFD-induced obesity via an AMPK-dependent pathway.

AMPK/PGC-1α/GLUT4-Mediated Effect of Icariin on Hyperlipidemia-Induced Non-Alcoholic Fatty Liver Disease and Lipid Metabolism Disorder in Mice

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease in the world. Therapeutic activity of icariin, a major bioactive component of Epimedii Herba, in NAFLD is still unknown. Herein, the C57BL/6J mice were fed with a high-fat diet for 16 weeks to establish a NAFLD model. Mice were assigned to five groups: control group, NAFLD group, and icariin treatment groups. Effects of icariin on blood indices, glucose tolerance, insulin sensitivity, histopathological morphology, cell apoptosis, lipid accumulation, and AMPK signaling were analyzed. In addition, another cohort of mice were assigned to five groups: control group, NAFLD group, dorsomorphin treatment group, icariin treatment group, and dorsomorphin + icariin treatment group. Expression of proteins in liver tissues associated with AMPK signaling, and levels of ALT and AST were evaluated. Icariin attenuated the NAFLD-induced increase of the TG, TC, LDL-C, ALT, AST levels. HDL-C levels were affected neither by NAFLD nor by icariin. Furthermore, icariin treatment (100-200 mg/kg) counteracted the NAFLD-reduced glucose tolerance and insulin sensitivity and modulated histopathological changes, cell apoptosis, and lipid accumulation in liver tissues. Additionally, icariin mitigated the NAFLD-induced up-regulation of the cleaved caspase 3/9, SREBP-1c, and DGAT-2 levels, and enhanced the expression level of CPT-1, p-ACC/ACC, AMPKα1, PGC-1α, and GLUT4. Effects of icariin on the AMPK signaling and levels of AST and ALT could be reversed by AMPK inhibitor, dorsomorphin. This paper investigates the glucose-reducing and lipid-lowering effects of icariin in NAFLD. Moreover, icariin might function through activating the AMPKα1/PGC-1α/GLTU4 pathway.

Regulatory mechanisms of energy metabolism and inflammation in oleic acid-treated HepG2 cells from Lactobacillus acidophilus NX2-6 extract

In this study, the cell-free extracts (CFE) of Lactobacillus acidophilus NX2-6 were utilized to treat oleic acid (OA)-induced hepatic steatosis. It was found that CFE treatment improved lipid metabolism in OA-induced hepatic steatosis model by downregulating several lipogenic genes but increasing expression levels of lipolysis-related genes. In addition, gene expression analysis revealed that CFE treatment promoted mitochondrial biogenesis and fission by upregulating the mRNA levels of PGC-1α, PGC-1β, Sirt1, NRF1, and Fis1. CFE treatment also increased protein expression of p-AMPKα, PGC-1α, ACOX1, and Sirt1 in OA-treated cells, suggesting that CFE possessed ability to improve energy metabolism. Furthermore, CFE treatment also reversed OA-induced oxidative stress by increasing CAT activity and protein level of Nrf-2 as well as reducing protein expression of ATF6, XBP1, GRP78, p50, and p-ERK, indicating that CFE could inhibit endoplasmic reticulum stress and sterile inflammation. Thus, L. acidophilus NX2-6 had potential to fight against NAFLD. PRACTICAL APPLICATIONS: Diet-induced hepatic steatosis is one of major public health concerns all over the world. Hepatic steatosis is accompanied by disregulation of lipid metabolism and energy metabolism, endoplasmic reticulum stress, oxidative stress as well as chronic inflammation. It is reported that probiotics are considered as emerging therapeutic strategy to alleviate hepatic steatosis. This study indicated potential applications of dead probiotics in the prevention of hepatic steatosis and development of functional foods.

Berberine Acts on C/EBPβ/lncRNA Gas5/miR-18a-5p Loop to Decrease the Mitochondrial ROS Generation in HK-2 Cells

BACKGROUND

Berberine (BBR) has therapeutic effect on diabetic nephropathy (DN), but its molecular mechanism is not completely clear.

METHODS

The DN model was established to observe the therapeutic effect of BBR. The expression levels of lncRNA Gas5 were detected by PCR. The transcriptional regulation of CCAAT enhancer binding protein beta (C/EBPβ) on Gas5 was analyzed by chromatin immunoprecipitation quantitative PCR (ChIP-qPCR) and luciferase reporter gene assay. The targeted regulation between Gas5 and miR-18a-5p and between miR-18a-5p and C/EBPβ 3'-untranslated region (3'-UTR) was also analyzed.

RESULTS

In HG environment, BBR decreased the mitochondrial reactive oxygen species (ROS) generation and activated the C/EBPβ expression in HK-2 cells; C/EBPβ could combine with the reaction element on the promoter of Gas5 to promote its expression. Gas5 also inhibited the miR-18a-5p expression as competing endogenous RNA (ceRNA) and reduce the negative regulatory effect of miR-18a-5p on C/EBPβ. BBR could activate C/EBPβ/peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) signal pathway, regulate mitochondrial energy metabolism, and inhibit ROS production and apoptosis by activating C/EBPβ/Gas5/miR-18a-5p positive feedback loop in HG environment. It also showed that BBR alleviated streptozotocin (STZ) induced renal injury in DN rats in vivo.

CONCLUSIONS

This study suggested that BBR could regulate the mitochondrial ROS generation by activating the positive feedback loop of C/EBPβ/Gas5/miR-18a-5p.

Understanding lipotoxicity in NAFLD pathogenesis: is CD36 a key driver?

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease worldwide. NAFLD stages range from simple steatosis (NAFL) to non-alcoholic steatohepatitis (NASH) which can progress to cirrhosis and hepatocellular carcinoma. One of the crucial events clearly involved in NAFLD progression is the lipotoxicity resulting from an excessive fatty acid (FFA) influx to hepatocytes. Hepatic lipotoxicity occurs when the capacity of the hepatocyte to manage and export FFAs as triglycerides (TGs) is overwhelmed. This review provides succinct insights into the molecular mechanisms responsible for lipotoxicity in NAFLD, including ER and oxidative stress, autophagy, lipoapotosis and inflammation. In addition, we highlight the role of CD36/FAT fatty acid translocase in NAFLD pathogenesis. Up-to-date, it is well known that CD36 increases FFA uptake and, in the liver, it drives hepatosteatosis onset and might contribute to its progression to NASH. Clinical studies have reinforced the significance of CD36 by showing increased content in the liver of NAFLD patients. Interestingly, circulating levels of a soluble form of CD36 (sCD36) are abnormally elevated in NAFLD patients and positively correlate with the histological grade of hepatic steatosis. In fact, the induction of CD36 translocation to the plasma membrane of the hepatocytes may be a determining factor in the physiopathology of hepatic steatosis in NAFLD patients. Given all these data, targeting the fatty acid translocase CD36 or some of its functional regulators may be a promising therapeutic approach for the prevention and treatment of NAFLD.

Effect of dietary oils from various sources on carbohydrate and fat metabolism in mice

Background

Dietary oils differ in their fatty acid composition and the presence of additional microcomponents (antioxidants, etc.). These differences are thought to invoke different biochemical pathways, thus affecting fats and carbohydrates metabolism differently. Olive oil (OO) and soybean oil (SO) are common vegetable oils in the local cuisine. Peanuts oils of local varieties are viewed as potential sources of dietary vegetable oils, especially in the food industry.

Objective

We examined the effect of four different dietary vegetable oils on carbohydrate and lipid metabolism in mice. The selected oils were OO, high in oleic acid, extracted from cultivated high oleic acid peanut (C-PO), regular peanut oil (PO), and SO.

Design

In this study, 32 male C57BL/6J mice were randomly divided into four groups (n = 8 in each group) and were fed with four different diets enriched with 4% (w/w) dietary vegetable oils (OO, C-PO, PO, or SO). After 10 weeks, the mice were sacrificed. Western blot was used to examine proteins such as phospho-AMP-activated protein kinase (p-AMPK), ace-tyl-CoA carboxylase (ACC), cluster of differentiation 36 (CD36), and Sirtuin 1 (SIRT1), whereas real-time polymerase chain reaction (PCR) was used to examine the expression of sterol regulatory element-binding protein-1c (SREBP-1C), fatty acid synthase (FAS), glucose-6-phosphatase (G6Pase), and CD36 transcripts.

Results

In mice-fed SO, lipid accumulation was predominately in adipose tissue, accompanied a tendency decrease in insulin sensitivity. Mice-fed OO had lower plasma triglycerides (TG) and increased hepatic CD36 gene expression. The C-PO group presented lower messenger RNA (mRNA) levels in the liver for all examined genes: SREBP-1c, FAS, G6Pase, and CD36. There were no significant differences in weight gain, plasma cholesterol and high-density lipoprotein (HDL) cholesterol levels, hepatic ACC, SIRT1, AMPK, and CD36 protein levels or in liver function among the diets.

Discussion

It seems that as long as fat is consumed in moderation, oil types may play a lesser role in the metabolism of healthy individuals.

Conclusion

This finding has the potential to increase flexibility in choosing oil types for consumption.

Sustained Activation of AMPK Enhances Differentiation of Human iPSC-Derived Cardiomyocytes via Sirtuin Activation

Recent studies suggest that metabolic regulation may improve differentiation of cardiomyocytes derived from induced pluripotent stem cells (iPSCs). AMP-activated protein kinase (AMPK) is a master regulator of metabolic activities. We investigated whether AMPK participates in iPSC-derived cardiomyocyte differentiation. We observed that AMPK phosphorylation at Thr172 increased at day 9 but then decreased after day 11 of differentiation to cardiomyocytes. Inhibition of AMPK with compound C significantly reduced mRNA and protein expression of cardiac troponins TNNT2 and TNNI3. Moreover, sustained AMPK activation using AICAR from days 9 to 14 of differentiation increased mRNA and protein expression of both TNNT2 and TNNI3. AICAR decreased acetylation of histone 3 at Lys9 and 56 and histone 4 at Lys16 (known target sites for nuclear-localized sirtuins [SIRT1, SIRT6]), suggesting that AMPK activation enhances sirtuin activity. Sustained AMPK activation during days 9–14 of differentiation induces sirtuin-mediated histone deacetylation and may enhance cardiomyocyte differentiation from iPSCs.

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iPSC-derived cardiomyocytes transiently increased AMPK phosphorylation at Thr172

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Chemical inhibition of AMPK with compound C decreased TNNI3 and TNNT2 expression

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Sustained activation of AMPK using AICAR increased expression of TNNT2 and TNNI3

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AICAR decreased acetylation of histones H3 (at Lys9 and Lys56) and H4 (at Lys16).

AMP-activated protein kinase in the grass carp Ctenopharyngodon idellus: Molecular characterization, tissue distribution and mRNA expression in response to overwinter starvation stress

Adenosine monophosphate-activated protein kinase (AMPK) is the main energy sensor in mammals, but limited information is available regarding its role as an energy sensor in nutrient-restricted fish particularly in period of overwinter starvation. The present study aimed to investigate the role of AMPK in the grass carp Ctenopharyngodon idellus through characterization of AMPK full-length cDNAs and the measurement of transcriptional activity in response to overwinter starvation. AMPK is a heterotrimeric serine/threonine kinase that consists of a catalytic alpha (α) subunit complexed with two regulatory subunits, beta (β) and gamma (γ). In our study, we identified nine isoforms of the AMPK family in grass carp and obtained their complete coding sequences (CDS). In the grass carp, the α subunit is encoded by two isoforms (α1 and α2). The β and γ subunits are encoded by three (β1a, β1b, β2) and four isoforms (γ1, γ2a, γ2b, γ3), respectively. AMPK isoforms in grass carp possess structural features similar to mammalian AMPK and exhibit a high degree of homology with other fish and vertebrate AMPK sequences. The mRNA of nine grass carp AMPK isoforms were found to be expressed in a wide range of tissues in vivo, but the abundance of each AMPK mRNA demonstrated a tissue-dependent expression pattern, indicating that they might be key complexes playing the role of energy metabolism sensors during overwinter starvation conditions. Compared to expression levels in control fish (week 0), the expression of various AMPK isoforms significantly increased in the hepatopancreas of fish exposed to 1 week or more of overwinter starvation conditions as follows: week 1 (AMPK α1 and AMPK α2), week8 (AMPK β1b and AMPK γ2b), week 12 (AMPK β2 and AMPK γ1), and week 16 (AMPK β1a, AMPK γ2a, and AMPK γ3). Additionally, compared to expression levels in control fish (week 0), the expression of various AMPK isoforms significantly increased in the adipose tissue of fish exposed to 1 week or more of overwinter starvation conditions as follows: week 1(AMPK β1a and AMPK β1b), week 4 (AMPK α1, AMPK α2, AMPK γ1, AMPK γ2b and AMPK γ3), and week 8 (AMPK β2 and AMPK γ2a). Further in vitro analysis revealed that the mRNA levels of AMPK isoforms in hepatocytes (AMPK α1, AMPK α2, AMPK β1a, AMPK β1b, AMPK β2, AMPK γ2b and AMPK γ3) and adipocytes (AMPK γ2a, AMPK γ2b and AMPK γ3) changed significantly with in the first 24 h of exposure to the overwinter starvation conditions. These findings confirm that nine AMPK subunits are present in grass carp and that all encode proteins with conserved functional domains. The nine AMPK subunits are all regulated at the transcriptional levels to manage excess energy expenditure during overwinter starvation stress.

Berberine Improves Glucose and Lipid Metabolism in HepG2 Cells Through AMPKα1 Activation

Aim

This study is designed to investigate whether or not AMP-activated protein kinase α1 (AMPKα1) is required for natural product berberine (BBR) to improve glucose and lipid metabolism in HepG2 cells.

Methods

AMPKα1 knocked-out (KO, AMPKα1^-/-) cells were obtained by co-transfection of the CRISPR/Cas9 KO and HDR (homology-directed repair) plasmid into HepG2 cells, as well as subsequent screen with puromycin. The expression levels of target proteins or mRNAs were determined by western blot or real-time RT-PCR, respectively. Cellular AMPK activity, glucose consumption, lactate release, glucose production, and lipid accumulation were determined by kits.

Results

The results showed that the AMPKα1 gene was successfully KO in HepG2 cells. In AMPKα1^-/- cells, the protein expression of AMPKα1 and phosphorylated-AMPKα1 (p-AMPKα1) disappeared, the level of total AMPKα declined to about 45–50% of wild type (p < 0.01), while p-AMPKα level and AMPK activity were reduced to less than 10% of wild type (p < 0.001). BBR increased p-AMPKα1, p-AMPKα, AMPK activity, and stimulated glucose consumption, lactate release, inhibited glucose production in wild type HepG2 cells (p < 0.05 or p < 0.01). BBR also reduced intracellular lipid accumulation and suppressed the expression of lipogenic genes in oleic acid (OA) treated wild type HepG2 cells (p < 0.05 or p < 0.01). In AMPKα1^-/- HepG2 cells, the stimulating effects of BBR on p-AMPKα1, p-AMPKα, AMPK activity, and its improving effects on glucose and lipid metabolism were completely abolished.

Conclusion

Our study proves that AMPKα1 plays a critical role for BBR to improve glucose and lipid metabolism in HepG2 cells. Our results will provide new information to further understand the molecular mechanisms of BBR.

Phytopharmacology and Clinical Updates of Berberis Species Against Diabetes and Other Metabolic Diseases

The incidences of diabetic mellitus and other metabolic diseases such as hypertension and hyperlipidemia are increasing worldwide; however, the current treatment is not able to control the rapidly increasing trend in diabetes mortality and morbidity. Studies related to the effectiveness of extracts and pure compounds obtained from plants have shown promising responses in preclinical and clinical studies related to these metabolic diseases. Plants belonging to the genus Berberis (Family: Berberidaceae) are widely distributed with nearly 550 species worldwide. Extracts and compounds obtained from Berberis species, especially Berberine alkaloid, showed effectiveness in the management of diabetes and other metabolic diseases. Various pharmacological experiments have been performed to evaluate the effects of Berberis extracts, berberine, and its natural and chemically synthesized derivatives against various cell and animal disease models with promising results. Various clinical trials conducted so far also showed preventive effects of Berberis extracts and berberine against metabolic diseases. The present review focuses on i) research updates on traditional uses, ii) phytopharmacology and clinical studies on Berberis species, and iii) active metabolites in the prevention and treatment of diabetes and other metabolic diseases with a detailed mechanism of action. Furthermore, the review critically analyzes current research gaps in the therapeutic use of Berberis species and berberine and provides future recommendations.

AMPK facilitates intestinal long-chain fatty acid uptake by manipulating CD36 expression and translocation

Cellular long-chain fatty acids' (LCFAs) uptake is a crucial physiological process that regulates cellular energy homeostasis. AMPK has been shown to modulate LCFAs uptake in several kinds of cells, but whether it exerts an impact on intestinal LCFAs uptake is not quite clear. In the current study, we found that AMPK reinforced LCFAs uptake in intestinal epithelial cells (IECs). Moreover, intestinal epithelium-specific AMPK deletion impaired intestinal LCFAs absorption and protected mice from high-fat diet-induced obesity. Mechanistically, we discovered that AMPK deletion reduced the CD36 protein level by upregulating Parkin-mediated polyubiquitination of CD36 in IECs. Furthermore, our results revealed that AMPK affected PARK2 (gene name of Parkin) mRNA stability in a YTHDF2-dependent manner through FTO-dependent demethylation of N⁶ -methyladenosine (m⁶ A). Besides, AMPK promoted the translocation of CD36 to the plasma membrane in IECs, but the inhibition of AKT signaling suppressed this effect, which also halted the accelerated fatty acid uptake induced by AMPK. These results suggest that AMPK facilitates the intestinal LCFAs uptake by upregulating CD36 protein abundance and promoting its membrane translocation simultaneously. Such findings shed light on the role of AMPK in the regulation of intestinal LCFAs uptake.

HDAC (Histone Deacetylase) Inhibitor Valproic Acid Attenuates Atrial Remodeling and Delays the Onset of Atrial Fibrillation in Mice

Supplemental Digital Content is available in the text.

Background:

A structural, electrical and metabolic atrial remodeling is central in the development of atrial fibrillation (AF) contributing to its initiation and perpetuation. In the heart, HDACs (histone deacetylases) control remodeling associated processes like hypertrophy, fibrosis, and energy metabolism. Here, we analyzed, whether the HDAC class I/IIa inhibitor valproic acid (VPA) is able to attenuate atrial remodeling in CREM-IbΔC-X (cAMP responsive element modulator isoform IbΔC-X) transgenic mice, a mouse model of extensive atrial remodeling with age-dependent progression from spontaneous atrial ectopy to paroxysmal and finally long-lasting AF.

Methods:

VPA was administered for 7 or 25 weeks to transgenic and control mice. Atria were analyzed macroscopically and using widefield and electron microscopy. Action potentials were recorded from atrial cardiomyocytes using patch-clamp technique. ECG recordings documented the onset of AF. A proteome analysis with consecutive pathway mapping identified VPA-mediated proteomic changes and related pathways.

Results:

VPA attenuated many components of atrial remodeling that are present in transgenic mice, animal AF models, and human AF. VPA significantly (P<0.05) reduced atrial dilatation, cardiomyocyte enlargement, atrial fibrosis, and the disorganization of myocyte’s ultrastructure. It significantly reduced the occurrence of atrial thrombi, reversed action potential alterations, and finally delayed the onset of AF by 4 to 8 weeks. Increased histone H4-acetylation in atria from VPA-treated transgenic mice verified effective in vivo HDAC inhibition. Cardiomyocyte-specific genetic inactivation of HDAC2 in transgenic mice attenuated the ultrastructural disorganization of myocytes comparable to VPA. Finally, VPA restrained dysregulation of proteins in transgenic mice that are involved in a multitude of AF relevant pathways like oxidative phosphorylation or RhoA (Ras homolog gene family, member A) signaling and disease functions like cardiac fibrosis and apoptosis of muscle cells.

Conclusions:

Our results suggest that VPA, clinically available, well-tolerated, and prescribed to many patients for years, has the therapeutic potential to delay the development of atrial remodeling and the onset of AF in patients at risk.

Hypolipidemic effects of herbal extracts by reduction of adipocyte differentiation, intracellular neutral lipid content, lipolysis, fatty acid exchange and lipid droplet motility

An increase in adipose tissue is caused by the increased size and number of adipocytes. Lipids accumulate in intracellular stores, known as lipid droplets (LDs). Recent studies suggest that parameters such as LD size, shape and dynamics are closely related to the development of obesity. Berberine (BBR), a natural plant alkaloid, has been demonstrated to possess anti-obesity effects. However, it remains unknown which cellular processes are affected by this compound or how effective herbal extracts containing BBR and other alkaloids actually are. For this study, we used extracts of Coptis chinensis, Mahonia aquifolium, Berberis vulgaris and Chelidonium majus containing BBR and other alkaloids and studied various processes related to adipocyte functionality. The presence of extracts resulted in reduced adipocyte differentiation, as well as neutral lipid content and rate of lipolysis. We observed that the intracellular fatty acid exchange was reduced in different LD size fractions upon treatment with BBR and Coptis chinensis. In addition, LD motility was decreased upon incubation with BBR, Coptis chinensis and Chelidonium majus extracts. Furthermore, Chelidonium majus was identified as a potent fatty acid uptake inhibitor. This is the first study that demonstrates the selected regulatory effects of herbal extracts on adipocyte function.

Protective Effects of Licochalcone A Ameliorates Obesity and Non-Alcoholic Fatty Liver Disease Via Promotion of the Sirt-1/AMPK Pathway in Mice Fed a High-Fat Diet

Licochalcone A is a chalcone isolated from Glycyrrhiza uralensis. It showed anti-tumor and anti-inflammatory properties in mice with acute lung injuries and regulated lipid metabolism through the activation of AMP-activated protein kinase (AMPK) in hepatocytes. However, the effects of licochalcone A on reducing weight gain and improving nonalcoholic fatty liver disease (NAFLD) are unclear. Thus, the present study investigated whether licochalcone A ameliorated weight loss and lipid metabolism in the liver of high-fat diet (HFD)-induced obese mice. Male C57BL/6 mice were fed an HFD to induce obesity and NAFLD, and then were injected intraperitoneally with licochalcone A. In another experiment, a fatty liver cell model was established by incubating HepG2 hepatocytes with oleic acid and treating the cells with licochalcone A to evaluate lipid metabolism. Our results demonstrated that HFD-induced obese mice treated with licochalcone A had decreased body weight as well as inguinal and epididymal adipose tissue weights compared with HFD-treated mice. Licochalcone A also ameliorated hepatocyte steatosis and decreased liver tissue weight and lipid droplet accumulation in liver tissue. We also found that licochalcone A significantly regulated serum triglycerides, low-density lipoprotein, and free fatty acids, and decreased the fasting blood glucose value. Furthermore, in vivo and in vitro, licochalcone A significantly decreased expression of the transcription factor of lipogenesis and fatty acid synthase. Licochalcone A activated the sirt-1/AMPK pathway to reduce fatty acid chain synthesis and increased lipolysis and β-oxidation in hepatocytes. Licochalcone A can potentially ameliorate obesity and NAFLD in mice via activation of the sirt1/AMPK pathway.

Hepatic upregulation of fetuin-A mediates acetaminophen-induced liver injury through activation of TLR4 in mice

Acetaminophen (APAP)-induced liver injury (AILI) is initiated by the generation of a reactive metabolite and ultimately leads to hepatocyte necrosis. Necrotic cells secrete damage-associated molecular patterns that activate hepatic nonparenchymal cells and induce an inflammatory response. Fetuin-A is a hepatokine with reported involvement in low-grade inflammation in many diseases, due to acting as an endogenous ligand for TLR4. However, little is known about the role of fetuin-A in AILI. In this study, we showed that fetuin-A is involved in the aggravation of hepatotoxicity during the initial phase of AILI progression. Treatment with APAP increased the expression and serum levels of fetuin-A in mice. Fetuin-A upregulated transcription of pro-inflammatory cytokines and chemokines through activation of TLR4 and also increased monocyte infiltration into the liver, leading to necroinflammatory reactions in AILI. However, these reactions were attenuated with the silencing of fetuin-A using adenoviral shRNA. As a result, mice with silenced fetuin-A exhibited less centrilobular necrosis and liver injury compared to controls in response to APAP. In conclusion, our results suggest that fetuin-A is an important hepatokine that mediates the hepatotoxicity of APAP through production of chemokines and thus regulates the infiltration of monocytes into the liver, a critical event in the inflammatory response during the initial phase of AILI. Our results indicate that a strategy based on the antagonism of fetuin-A may be a novel therapeutic approach to the treatment of acetaminophen-induced acute liver failure.

Effects of berberine on glucose-lipid metabolism, inflammatory factors and insulin resistance in patients with metabolic syndrome

Effects of berberine on glucose-lipid metabolism, inflammatory factors and insulin resistance in patients with metabolic syndrome were investigated. Eighty patients with metabolic syndrome treated in Linyi Central Hospital from January 2017 to December 2017 were selected and divided into control group (n=40) and observation group (n=40). Patients in control group were treated with regular therapy using the Western medicine and drugs, while those in observation group, based on the treatment in control group, were treated with berberine. Changes in relevant indexes to blood glucose and lipid metabolisms and inflammatory factors were compared between the two groups. The correlation of inflammatory factor with fasting blood glucose, insulin resistance, triglyceride and total cholesterol was analyzed. At 1 month after treatment, levels of fasting blood glucose, 2 h postprandial blood glucose, insulin resistance index and blood lipid indexes in both groups were lower than those at 1 week after treatment (P<0.05). At 1 month after treatment, levels of fasting blood glucose, 2 h postprandial blood glucose, insulin resistance index and blood lipid indexes in observation group were significantly lower than those in control group during the same period (P<0.05). Moreover, levels of high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in both groups at 1 month after treatment were lower than those at 1 week after treatment (P<0.05), and they were lower in observation group at 1 month after treatment than those in control group during the same period (P<0.05). Finally, hs-CRP was positively correlated with fasting blood glucose, insulin resistance, total cholesterol and triglyceride. The combined application of berberine in patients with metabolic syndrome can effectively regulate blood glucose and blood lipid of patients, alleviate insulin resistance and reduce the level of inflammatory response in the body.

Ginsenoside Rg1 Ameliorates Palmitic Acid-Induced Hepatic Steatosis and Inflammation in HepG2 Cells via the AMPK/NF-κB Pathway

Nonalcoholic fatty liver disease (NAFLD) is one of the common diseases in the world, and it can progress from simple lipid accumulation to sustained inflammation. The present study was designed to investigate the effects and underlying mechanisms of ginsenoside Rg1 (G-Rg1) treatment on NAFLD in vitro. HepG2 cells were treated with palmitic acid (PA) to induce steatosis and inflammation and then successively incubated with G-Rg1. Lipids accumulation was analyzed by Oil Red O staining and intracellular triglyceride (TG) quantification. Inflammatory conditions were examined by quantifying the levels of cell supernatant alanine transaminase/aspartate aminotransferase (ALT/AST) and secretory proinflammatory cytokines, including IL-1β, IL-6, and TNF-α in the cell supernatants. Quantitative RT-PCR and western blotting were used to measure the expressions of genes and proteins associated with lipogenic synthesis and inflammation, including AMP-activated protein kinase (AMPK) and nuclear factor-kappa B (NF-κB) pathways. HepG2 cells were pretreated with an AMPK inhibitor; then, Oil Red O staining and TG quantification were performed to study the lipid deposition. Phospho-AMPK (Thr172) (p-AMPK) and phospho-acetyl-CoA carboxylase (Ser79) (p-ACCα) were quantified by immunoblotting. Immunofluorescence was performed to demonstrate the nuclear translocation of NF-κB P65. The present study showed that PA markedly increased the intracellular lipid droplets accumulation and TG levels, but decreased AMPK phosphorylation and the expressions of its downstream lipogenic genes. However, G-Rg1 alleviated hepatic steatosis and reduced the intracellular TG content; these changes were accompanied by the activation of the AMPK pathway. In addition, blocking AMPK by using the AMPK inhibitor markedly abolished the G-Rg1-mediated protection against PA-induced lipid deposition in HepG2 cells. Furthermore, G-Rg1 reduced the ALT/AST levels and proinflammatory cytokines release, which were all enhanced by PA. These effects were correlated with the inactivation of the NF-κB pathway and translocation of P65 from the cytoplasm to the nucleus. Overall, these results suggest that G-Rg1 effectively ameliorates hepatic steatosis and inflammation, which might be associated with the AMPK/NF-κB pathway.

9-O-benzoyl-substituted berberine exerts a triglyceride-lowering effect through AMPK signaling pathway in human hepatoma HepG2 cells

Berberine is an isoquinoline alkaloid extracted from Rhizoma coptidis and shows anti-hyperlipidemia effect in vivo and in vitro. We previously found that berberine could decrease the intracellular triglyceride content in human hepatoma HepG2 cells through activation of AMP-activated protein kinase (AMPK), a major regulator of lipid metabolism. Herein, to find a more effective agent, several berberine analogues (A1-A13) were isolated and synthesized, and the triglyceride-lowering effects and potential mechanisms were investigated in HepG2 cells. Among these berberine analogues, 9-O-benzoyl-substituted berberine (A13) showed strong affinity to AMPK and significantly up-regulated the levels of phospho-Thr172 AMPK α subunit. Meanwhile, A13 reduced the cellular triglyceride levels. Furthermore, A13 could mediate the mRNA levels of downstream proteins involved in triglyceride synthesis and fatty acid oxidation of AMPK signaling pathway. These results suggested that A13 exerts a triglyceride-lowering effect via stimulation of AMPK pathway, which may be beneficial to regulate hyperlipidemia.

Ginkgolide C reduced oleic acid-induced lipid accumulation in HepG2 cells

Ginkgolide C, isolated from Ginkgo biloba, is a diterpene lactone that has multiple biological functions and can improve Alzheimer disease and platelet aggregation. Ginkgolide C also inhibits adipogenesis in 3T3-L1 adipocytes. The present study evaluated whether ginkgolide C reduced lipid accumulation and regulated the molecular mechanism of lipogenesis in oleic acid-induced HepG2 hepatocytes. HepG2 cells were treated with 0.5 mM oleic acid for 48 h to induce a fatty liver cell model. Then, the cells were exposed to various concentrations of ginkgolide C for 24 h. Staining with Oil Red O and the fluorescent dye BODIPY 493/503 revealed that ginkgolide C significantly reduced excessive lipid accumulation in HepG2 cells. Ginkgolide C decreased peroxisome proliferator-activated receptor γ and sterol regulatory element-binding protein 1c to block the expression of fatty acid synthase. Ginkgolide C treatment also promoted the expression of adipose triglyceride lipase and the phosphorylation level of hormone-sensitive lipase to enhance the decomposition of triglycerides. In addition, ginkgolide C stimulated CPT-1 to activate fatty acid β-oxidation, significantly increased sirt1 and phosphorylation of AMP-activated protein kinase (AMPK), and decreased expression of acetyl-CoA carboxylase for suppressed fatty acid synthesis in hepatocytes. Taken together, our results suggest that ginkgolide C reduced lipid accumulation and increased lipolysis through the sirt1/AMPK pathway in oleic acid-induced fatty liver cells.

Dietary Tomato Powder Inhibits High-Fat Diet-Promoted Hepatocellular Carcinoma with Alteration of Gut Microbiota in Mice Lacking Carotenoid Cleavage Enzymes

Both incidence and death rate due to liver cancer have increased in the United States. Higher consumption of lycopene-rich tomato and tomato products is associated with a decreased risk of cancers. β-Carotene-15, 15'-oxygenase (BCO1), and β-carotene-9', 10'-oxygenase (BCO2) cleave lycopene to produce bioactive apo-lycopenoids. Although BCO1/BCO2 polymorphisms affect human and animal lycopene levels, whether dietary tomato consumption can inhibit high-fat diet (HFD)-promoted hepatocellular carcinoma (HCC) development and affect gut microbiota in the absence of BCO1/BCO2 is unclear. BCO1/BCO2 double knockout mice were initiated with a hepatic carcinogen (diethylnitrosamine) at 2 weeks of age. At 6 weeks of age, the mice were randomly assigned to an HFD (60% of energy as fat) with or without tomato powder (TP) feeding for 24 weeks. Results showed that TP feeding significantly decreased HCC development (67%, 83%, and 95% reduction in incidence, multiplicity, and tumor volume, respectively, P < 0.05). Protective effects of TP feeding were associated with (1) decreased hepatic inflammatory foci development and mRNA expression of proinflammatory biomarkers (IL1β, IL6, IL12α, monocyte chemoattractant protein-1, and inducible NO synthase); (2) increased mRNA expression of deacetylase sirtuin 1 and nicotinamide phosphoribosyltransferase involving NAD⁺ production; and (3) increased hepatic circadian clock genes (circadian locomotor output cycles kaput, period 2, and cryptochrome-2, Wee1). Furthermore, TP feeding increased gut microbial richness and diversity, and significantly decreased the relative abundance of the genus Clostridium and Mucispirillum, respectively. The present study demonstrates that dietary tomato feeding independent of carotenoid cleavage enzymes prevents HFD-induced inflammation with potential modulating gut microbiota and inhibits HFD-promoted HCC development.

The Chinese medicine Chai Hu Li Zhong Tang protects against non-alcoholic fatty liver disease by activating AMPKα

An effective treatment for non-alcoholic fatty liver disease (NAFLD) is urgently needed. In the present study, we investigated whether the Chinese medicine Chai Hu Li Zhong Tang (CHLZT) could protect against the development of NAFLD. Rats in an animal model of NAFLD were treated with CHLZT, and their serum levels of cholesterol (TC), triglycerides (TG), high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were detected with an automatic biochemical analyzer. A cellular model of NAFLD was also established by culturing HepG2 cells in a medium that contained a long chain fat emulsion. Those cells were treated with CHLZT that contained serum from rats. After treatment, the levels of adenylate-activated protein kinase (AMPK) α (AMPKα), p-AMPKα, acetyl coenzyme A carboxylase (ACC) α (ACCα), pACCα, PPARγ, and SREBP-2 were detected. The AMPK agonist, acadesine (AICAR), was used as a positive control compound. Our results showed that CHLZT or AICAR significantly decreased the serum levels of TG, TC, LDL-C, AST, ALT, and insulin in NAFLD rats, and significantly increased their serum HDL-C levels. Treatments with CHLZT or AICAR significantly decreased the numbers of lipid droplets in NAFLD liver tissues and HepG2 cells. CHLZT and AICAR increased the levels of p-AMPKα and PPARγ in the NAFLD liver tissues and HepG2 cells, but decreased the levels of ACC-α, p-ACC-α, SREBP-2, and 3-hydroxyl-3-methylglutaryl-coenzyme A reductase (HMGR). CHLZT protects against NAFLD by activating AMPKα, and also by inhibiting ACC activity, down-regulating SREBP2 and HMGR, and up-regulating PPAR-γ. Our results suggest that CHLZT might be useful for treating NAFLD in the clinic.

Berberine attenuates apoptosis in rat retinal Müller cells stimulated with high glucose via enhancing autophagy and the AMPK/mTOR signaling

Berberine (BBR) has beneficial effects on diabetes and the multiple complications of diabetes due to its anti-apoptotic activity; however, the effect of BBR on diabetic retinopathy and its mechanism of action have not been clarified. The present study investigated the effect of BBR on Müller cells stimulated with high glucose (HG). Primary retinal Müller cells were incubated with high glucose to induce cell apoptosis; cells were pretreated with the AMPK inhibitor compound C and the AMPK activator AICAR to further explore the role of the AMPK/mTOR signaling pathway in the anti-apoptotic action of BBR. Immunofluorescence was used to measure apoptosis and autophagy. Western blot analysis was employed to determine the levels of p-AMPK and p-mTOR, as well as apoptosis-related proteins and autophagy-related proteins in Müller cells. Our results showed that BBR attenuated apoptosis, up regulated Bcl-2 and down regulated Bax and caspase-3 expression; enhanced the formation of autophagy, elevated the expression of Beclin-1 and LC3II and activated the AMPK/mTOR signaling pathway in Müller cells under high glucose conditions compared with the control group. The effect of BBR was partly blocked by compound C and strengthened by AICAR. BBR may have therapeutic potential to protect Müller cells from high-glucose-inducing apoptosis through enhancing autophagy and activating the AMPK/mTOR signaling pathway.

Growth performance, innate immune responses and disease resistance of fingerling blunt snout bream, Megalobrama amblycephala adapted to different berberine-dietary feeding modes

A 8-week feeding trial was conducted to evaluate the effect of different berberine-dietary feeding modes on growth, non-specific immune responses and disease resistance of blunt snout bream, Megalobrama amblycephala. Fish (average initial weight 4.70 ± 0.02 g) were fed two fat levels (5% and 10%) diets in three berberine-feeding modes (supplementing 50 mg/kg berberine continuously, two-week or four-week intervals) with four replicates, respectively. Then, fish were challenged by Aeromonas hydrophila and mortality was recorded for the next 96 h after feeding trial. The results showed that different feeding modes of berberine significantly influenced growth, innate immunity and antioxidant capability of fish. Fish fed normal diet with 50 mg/kg berberine at two-week interval mode reflected remarkably (P < 0.05) high weight gain (WG). Plasma TC and TG contents were significantly (P < 0.05) decreased. The lysozyme (LYZ) activities, complement component 3 (C3) and complement component 4 (C4) concentrations were significantly (P < 0.05) increased. Fish not only exhibited relatively low hepatopancreas malondialdehyde (MDA) and lipid peroxide (LPO) contents, but also significantly (P < 0.05) improved superoxide dismutase (SOD) and catalase (CAT) activities. Fish mortality after challenged by Aeromonas hydrophila was decreased. Same results were also presented in fish fed high-fat diet with 50 mg/kg berberine at two-week, four-week intervals or continuous feeding modes. Based on fish healthy improvement and feeding cost saving, blunt snout bream fed normal diet with 50 mg/kg berberine at two-week interval or fed high-fat diet with berberine at two-week or four-week intervals were optimal feeding mode, respectively.