Antidiabetic and antisteatotic effects of the selective fatty acid synthase (FAS) inhibitor platensimycin in mouse models of diabetes. Proc Natl Acad Sci U S A. 2011;108:5378-5383. [PMID: 21389266 DOI: 10.1073/pnas.1002588108]

Advances in management of metabolic dysfunction-associated steatotic liver disease: from mechanisms to therapeutics

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the leading cause of chronic liver disease that affects over 30% of the world's population. For decades, the heterogeneity of non-alcoholic fatty liver disease (NAFLD) has impeded our understanding of the disease mechanism and the development of effective medications. However, a recent change in the nomenclature from NAFLD to MASLD emphasizes the critical role of systemic metabolic dysfunction in the pathophysiology of this disease and therefore promotes the progress in the pharmaceutical treatment of MASLD. In this review, we focus on the mechanism underlying the abnormality of hepatic lipid metabolism in patients with MASLD, and summarize the latest progress in the therapeutic medications of MASLD that target metabolic disorders.

Pharmacologic inhibition of lipogenesis for the treatment of NAFLD

The hepatic accumulation of excess triglycerides is a seminal event in the initiation and progression of non-alcoholic fatty liver disease (NAFLD). Hepatic steatosis occurs when the hepatic accrual of fatty acids from the plasma and de novo lipogenesis (DNL) is no longer balanced by rates of fatty acid oxidation and secretion of very low-density lipoprotein-triglycerides. Accumulating data indicate that increased rates of DNL are central to the development of hepatic steatosis in NAFLD. Whereas the main drivers in NAFLD are transcriptional, owing to both hyperinsulinemia and hyperglycaemia, the effectors of DNL are a series of well-characterised enzymes. Several have proven amenable to pharmacologic inhibition or oligonucleotide-mediated knockdown, with lead compounds showing liver fat-lowering efficacy in phase II clinical trials. In humans with NAFLD, percent reductions in liver fat have closely mirrored percent inhibition of DNL, thereby affirming the critical contributions of DNL to NAFLD pathogenesis. The safety profiles of these compounds have so far been encouraging. It is anticipated that inhibitors of DNL, when administered alone or in combination with other therapeutic agents, will become important agents in the management of human NAFLD.

Lipid Metabolism in Metabolic-Associated Steatotic Liver Disease (MASLD)

Metabolic-associated steatotic liver disease (MASLD) is a cluster of pathological conditions primarily developed due to the accumulation of ectopic fat in the hepatocytes. During the severe form of the disease, i.e., metabolic-associated steatohepatitis (MASH), accumulated lipids promote lipotoxicity, resulting in cellular inflammation, oxidative stress, and hepatocellular ballooning. If left untreated, the advanced form of the disease progresses to fibrosis of the tissue, resulting in irreversible hepatic cirrhosis or the development of hepatocellular carcinoma. Although numerous mechanisms have been identified as significant contributors to the development and advancement of MASLD, altered lipid metabolism continues to stand out as a major factor contributing to the disease. This paper briefly discusses the dysregulation in lipid metabolism during various stages of MASLD.

Hepatic FASN deficiency differentially affects nonalcoholic fatty liver disease and diabetes in mouse obesity models

Nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes are interacting comorbidities of obesity, and increased hepatic de novo lipogenesis (DNL), driven by hyperinsulinemia and carbohydrate overload, contributes to their pathogenesis. Fatty acid synthase (FASN), a key enzyme of hepatic DNL, is upregulated in association with insulin resistance. However, the therapeutic potential of targeting FASN in hepatocytes for obesity-associated metabolic diseases is unknown. Here, we show that hepatic FASN deficiency differentially affects NAFLD and diabetes depending on the etiology of obesity. Hepatocyte-specific ablation of FASN ameliorated NAFLD and diabetes in melanocortin 4 receptor-deficient mice but not in mice with diet-induced obesity. In leptin-deficient mice, FASN ablation alleviated hepatic steatosis and improved glucose tolerance but exacerbated fed hyperglycemia and liver dysfunction. The beneficial effects of hepatic FASN deficiency on NAFLD and glucose metabolism were associated with suppression of DNL and attenuation of gluconeogenesis and fatty acid oxidation, respectively. The exacerbation of fed hyperglycemia by FASN ablation in leptin-deficient mice appeared attributable to impairment of hepatic glucose uptake triggered by glycogen accumulation and citrate-mediated inhibition of glycolysis. Further investigation of the therapeutic potential of hepatic FASN inhibition for NAFLD and diabetes in humans should thus consider the etiology of obesity.

Classification analysis of fatty acid synthase inhibitors using multialgorithms on topological descriptors and structural fingerprints

Fatty acid synthase (FASN) is one of the enzymes required for fatty acid biosynthesis and is expressed as low or absent in most normal cells/tissues. However, this enzyme is upregulated in various cancer cells; hence, it can act as an important target to design and develop novel FASN inhibitors for cancer therapy. In the present investigation, a series of structurally diverse compounds that possessed FASN inhibitory activities were subjected to classification analysis using different algorithms such as support vector machine, decision tree, Naïve Bayes and random forest. The physicochemical descriptors and MACCS fingerprints were calculated using PaDEL software, and the WEKA software was utilized for the classification model building. The statistical parameters/confusion matrix calculated from the analysis revealed that the selected models have significant predictive performances. The results showed that the topological properties of the molecules are the main determinant for the activity classification. The key descriptors comprised of hydrogen bonding groups, especially acceptor (nHBAcc, minHBint9, minHBint5 and nwHBa), charge on the topological surface of the molecules (JGI10 & GGI2), ionization potential (GATS5i and GATS1i) and branching and distance between the groups (ETA_Eta_B_RC) are significantly contributed in the classification models. Further, the presence of heteroatoms (MACCSFP82, MACCSFP93 and MACCSFP131), especially nitrogen atom(s) and hydrogen bond acceptor groups (N-N group, NC(=O)N, N-C(=O)), actively contributed to the inhibitory activities. The results concluded that the topological polar properties concentrated in a specific region have significant FASN inhibitory activity. Hence, these results shall be used to develop novel molecules with increased FASN inhibitory activity.

Potential Therapies Targeting the Metabolic Reprogramming of Diabetes-Associated Breast Cancer

In recent years, diabetes-associated breast cancer has become a significant clinical challenge. Diabetes is not only a risk factor for breast cancer but also worsens its prognosis. Patients with diabetes usually show hyperglycemia and hyperinsulinemia, which are accompanied by different glucose, protein, and lipid metabolism disorders. Metabolic abnormalities observed in diabetes can induce the occurrence and development of breast cancer. The changes in substrate availability and hormone environment not only create a favorable metabolic environment for tumorigenesis but also induce metabolic reprogramming events required for breast cancer cell transformation. Metabolic reprogramming is the basis for the development, swift proliferation, and survival of cancer cells. Metabolism must also be reprogrammed to support the energy requirements of the biosynthetic processes in cancer cells. In addition, metabolic reprogramming is essential to enable cancer cells to overcome apoptosis signals and promote invasion and metastasis. This review aims to describe the major metabolic changes in diabetes and outline how cancer cells can use cellular metabolic changes to drive abnormal growth and proliferation. We will specifically examine the mechanism of metabolic reprogramming by which diabetes may promote the development of breast cancer, focusing on the role of glucose metabolism, amino acid metabolism, and lipid metabolism in this process and potential therapeutic targets. Although diabetes-associated breast cancer has always been a common health problem, research focused on finding treatments suitable for the specific needs of patients with concurrent conditions is still limited. Most studies are still currently in the pre-clinical stage and mainly focus on reprogramming the glucose metabolism. More research targeting the amino acid and lipid metabolism is needed.

Fatty Acid Synthase (FASN): A Patent Review Since 2016-Present

INTRODUCTION

Fatty acid synthase (FASN), is a key metabolic enzyme involved in fatty acid biosynthesis and is an essential target for multiple disease progressions like cancer, obesity, NAFLD, etc. Aberrant expression of FASN is associated with deregulated energy metabolism of cells in these diseases.

AREA COVERED

This article provides a summary of the most recent developments in the discovery of novel FASN inhibitors with potential therapeutic uses in cancer, obesity, and other metabolic disorders such as nonalcoholic fatty liver disease from 2016 to the present. The recently published patent applications and forthcoming clinical data of FASN inhibitors from both academia and the pharma industries are also highlighted in this study.

EXPERT OPINION

The implication of FASN in multiple diseases has provided an impetus for developing novel inhibitors by both pharma companies and academia. Critical analysis of the patent literature reveals the exploration of diverse molecular scaffolds to identify potential FASN inhibitors that target the different catalytic domains of the enzyme. In spite of these multifaceted efforts, only one molecule, TVB-2640, has reached phase II trials for nonalcoholic steatohepatitis (NASH) and many malignancies. However, thecombined efforts of pharma companies to produce several FASN inhibitors might facilitate the clinical translation of this unique class of inhibitors. Nevertheless, concerted efforts towards developing multiple FASN inhibitors by pharma companies might facilitate the clinical translation of this novel class of inhibitors.

Effect of Pseudostellaria heterophylla polysaccharide on the growth and liver metabolism of chicks

In this study, the effects of Pseudostellaria heterophylla polysaccharide (PHP) on the growth, development, and liver metabolism of chicks were investigated by feeding chicks diets. Four hundred 7-d-old Gushi roosters were selected and randomly divided into four groups, labeled A, B, C, and D. Group A was fed the basal diet, and Groups B, C, and D were fed 100, 200, and 400 mg PHP per kilogram of basal diet, respectively. At 14, 21, 28 and 35 d of age, five chicks were randomly selected from each group to collect samples for index detection. The results showed that compared with Group A, there were significant reduction in average daily feed intake (ADFI) and feed-to-weight ratio (F/G) at 14, 21, and 28 d (P < 0.05), significant increase in average daily gain (ADG) at 21, 28 d (P < 0.05), significantly increased levels of total protein (TP), albumin (ALB), insulin (INS), thyroxine (T3), growth hormone (GH) at 14, 28 d (P < 0.05), significantly decreased levels of glucose (GLU), total cholesterol (TC), glucagon (GC), and triglyceride (TG) at 28 d in Group C (P < 0.05). There were significantly increased levels of TP, ALB at 14, 21 d (P < 0.05), significantly increased level of TP at 35 d (P < 0.05), significantly increased level of GH at 28 d (P < 0.05), significantly decreased levels of GLU, GC at 28 d (P < 0.05), significant reduction in F/G at 14, 21 d in Groups B and D (P < 0.05). Based on the above results, the livers from chicks in Groups A and C at 28 d were selected for transcriptome sequencing. The sequencing results showed that significantly differentially expressed genes (SDEGs) were enriched in growth and development, oxidative phosphorylation, the PPAR signaling pathway and the lipid metabolism pathway. All these results revealed that the addition of 200 mg/kg PHP in the diet promoted the growth and development, lipid metabolism and energy metabolism of chicks, inhibit inflammation and tumor development, and improve the function of the liver.

Acetyl-CoA-mediated autoacetylation of fatty acid synthase as a metabolic switch of de novo lipogenesis in Drosophila

De novo lipogenesis is a highly regulated metabolic process, which is known to be activated through transcriptional regulation of lipogenic genes, including fatty acid synthase (FASN). Unexpectedly, we find that the expression of FASN protein remains unchanged during Drosophila larval development from the second to the third instar larval stages (L2 to L3) when lipogenesis is hyperactive. Instead, acetylation of FASN is significantly upregulated in fast-growing larvae. We further show that lysine K813 residue is highly acetylated in developing larvae, and its acetylation is required for elevated FASN activity, body fat accumulation, and normal development. Intriguingly, K813 is autoacetylated by acetyl-CoA (AcCoA) in a dosage-dependent manner independent of acetyltransferases. Mechanistically, the autoacetylation of K813 is mediated by a novel P-loop-like motif (N-xx-G-x-A). Lastly, we find that K813 is deacetylated by Sirt1, which brings FASN activity to baseline level. In summary, this work uncovers a previously unappreciated role of FASN acetylation in developmental lipogenesis and a novel mechanism for protein autoacetylation, through which Drosophila larvae control metabolic homeostasis by linking AcCoA, lysine acetylation, and de novo lipogenesis.

Nuclease treatment enhanced the ameliorative effect of yeast culture on epidermal mucus, hepatic lipid metabolism, inflammation response and gut microbiota in high-fat diet-fed zebrafish

As a functional feed additive, yeast cultures are rich in nucleotides, and adding extra nuclease can significantly increase the content of nucleotides in yeast culture. In this experiment, the effects on growth, epidermal mucus, liver and intestinal health of zebrafish were evaluated by supplementing the yeast culture or nuclease-treated yeast culture with a high-fat diet (HFD). One-month-old zebrafish were fed four diets: normal diet (NORM), HFD, yeast culture diet (YC), and nuclease-treated yeast culture diet (YC (N)) for three weeks. Results showed that the complement 4 activity of the epidermal mucus in YC (N) group was significantly higher than those in HFD and YC groups (P < 0.05). The YC and YC (N) significantly reduced the content of hepatic triglyceride caused by HFD (P < 0.05). Moreover, compared with the YC group, the YC (N) significantly increased the expression of lipolysis genes, such as PPARα, PGC1α, ACOX3 (P < 0.05). Compared with the YC group, the YC (N) group significantly increased the expression of liver pro-inflammatory factors TNFα, IL-6, IL-1β and anti-inflammatory factors TGFβ, IL-10 (P < 0.05). The diet YC and YC (N) significantly improved the height of the intestinal villus (P < 0.05). Compared with the HFD group, the YC (N) group significantly increased the expression of intestinal pro-inflammatory factors TNFα, IL-6 and anti-inflammatory factors TGFβ, IL-10 (P < 0.05). The YC (N) group significantly decreased the abundance of intestinal Proteobacteria and Acinetobacter, and increased the abundance of intestinal Actinobacteria, Mycobacterium and Rhodobacter (P < 0.05). In conclusion, compared with the supplement of yeast culture, nuclease treated yeast culture can further alleviate the adverse effects of HFD on liver and intestinal health, and be used as feed additives for the nutritional and immune regulation of fish.

Blocking Lipid Uptake Pathways Does not Prevent Toxicity in Adipose Triglyceride Lipase (ATGL) Deficiency

Lipid accumulation in nonadipose tissues can cause lipotoxicity, leading to cell death and severe organ dysfunction. Adipose triglyceride lipase (ATGL) deficiency causes human neutral lipid storage disease and leads to cardiomyopathy; ATGL deficiency has no current treatment. One possible approach to alleviate this disorder has been to alter the diet and reduce the supply of dietary lipids and, hence, myocardial lipid uptake. However, in this study, when we supplied cardiac Atgl KO mice a low- or high-fat diet, we found that heart lipid accumulation, heart dysfunction, and death were not altered. We next deleted lipid uptake pathways in the ATGL-deficient mice through the generation of double KO mice also deficient in either cardiac lipoprotein lipase or cluster of differentiation 36, which is involved in an lipoprotein lipase-independent pathway for FA uptake in the heart. We show that neither deletion ameliorated ATGL-deficient heart dysfunction. Similarly, we determined that non-lipid-containing media did not prevent lipid accumulation by cultured myocytes; rather, the cells switched to increased de novo FA synthesis. Thus, we conclude that pathological storage of lipids in ATGL deficiency cannot be corrected by reducing heart lipid uptake.

Progress in research of lipogenesis inhibitors for treatment of nonalcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the main cause of chronic liver disease. At present, the main clinical treatment for NAFLD is diet adjustment, exercise, and weight loss, but the effect is poor, and there is still a lack of recognized drugs with significant efficacy in NAFLD. In recent years, with the in-depth study of the pathogenesis of NAFLD, it has been found that the core enzymes that inhibit intrahepatic de novo lipogenesis (DNL), including citrate/isocitrate carrier (CIC), ATP-citrate lyase (ACLY), acetyl-CoA carboxylase (ACC), fatty acid synthase (FASN), and stearoyl-CoA desaturase 1 (SCD1), can improve hepatic steatosis and provide a new method for the treatment of NAFLD. This article reviews the research progress of five different types of lipogenesis inhibitors for treatment of NAFLD.

Mitoxantrone alleviates hepatic steatosis induced by high-fat diet in broilers

Metabolic-dysfunction-associated fatty liver disease (MAFLD) is a common nutritional metabolic disease in poultry that seriously compromises the health of chickens and reduces the economic benefits of the industry. In this study, we investigated the therapeutic effect of mitoxantrone (MTX) on hepatic steatosis in broilers. We constructed a steatosis cell model in vitro by adding oleic acid and palmitic acid to chicken hepatocytes (LMH cells), to examine influence of MTX on fat deposition on LMH cells. To determine the effects of MTX on hepatic steatosis in broiler livers in vivo, broilers were fed a high-fat diet to establish a fatty liver model. Our data show that MTX reduced the triglyceride (TG) levels and total cholesterol levels in LMH cells. In the MAFLD chick model, MTX decreased mRNA abundance of hepatic-lipid-synthesis-related gene such as FASN and increased mRNA abundance of fatty-acid-β-oxidation-related genes such as CPT1, PPARα, and reduced hepatic TG levels. MTX also reduced serum lipid and the percentage of abdominal fat. These results suggest that MTX improves hepatic steatosis in broilers as well as reduces circulating lipid levels and fat accumulation in broilers. Our work provides a promising therapeutic strategy for MAFLD and excessive fat accumulation in broiler chickens.

Impact of NAFLD and its pharmacotherapy on lipid profile and CVD

Atherosclerotic cardiovascular disease (ASCVD) remains the leading cause of death worldwide. Increasing evidence suggests that, in addition to traditional metabolic risk factors such as obesity, hypercholesterolemia, hypertension, diabetes mellitus, and insulin resistance (IR), nonalcoholic fatty liver disease (NAFLD) is an emerging driver of ASCVD via multiple mechanisms, mainly by disrupting lipid metabolism. The lack of pharmaceutical treatment has spurred substantial investment in the research and development of NAFLD drugs. However, many reagents with promising therapeutic potential for NAFLD also have considerable impacts on the circulating lipid profile. In this review, we first summarize the mechanisms linking lipid dysregulation in NAFLD to the progression of ASCVD. Importantly, we highlight the potential risks of/benefits to ASCVD conferred by NAFLD pharmaceutical treatments and discuss potential strategies and next-generation drugs for treating NAFLD without the unwanted side effects.

Fatty acid synthase (Fasn) inhibits the expression levels of immune response genes via alteration of alternative splicing in islet cells

BACKGROUND

Increasing evidence has shown that fatty acid synthase (Fasn) is associated with diabetes mellitus (DM) and insulin resistance, however, it remains unclear how Fasn upregulation leads to dysregulation of energy homeostasis in islet cells. Consequently, uncovering the function of Fasn in islet cells. Consequently, uncovering the function of FASN in islet cells is immensely important for finding a treatment target.

AIM

In this study, we elucidated the biological function of Fasn on the target genes in a rat insulinoma INS-1 cell line.

METHODS

We created a Fasn overexpressing rat insulinoma cell line (Fasn-OE), and performed bulk RNA-sequencing (RNA-seq) experiments on Fasn-OE and INS-1 (control) cells. We first identified differentially expressed genes (DEGs) using Bioconductor package edgeR, and then discovered enriched gene ontology terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways using the KEGG Orthology Based Annotation System (KOBAS) 2.0 web server. Furthermore, we identified alternative splicing events (ASEs) and regulated alternative splicing events (RASEs) by applying the ABLas pipeline. The reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used for validation of selected differentially expressed genes (DEGs) and Fasn-regulated alternative splicing genes (RASGs).

RESULTS

In this study we found that Fasn overexpression led to significant changes of gene expression profiles, including downregulations of mRNA levels of immune related genes, including Bst2, Ddit3, Isg15, Mx2, Oas1a, Oasl, and RT1-S3 in INS-1 cell line. Furthermore, Fasn positively regulated the expression of transcription factors such as Fat1 and Ncl diabetes-related genes. Importantly, Fasn overexpression to result in alternative splicing events including in a metabolism-associated ATP binding protein mRNA Abcc5. In Gene Ontology analysis, the downregulated genes in Fasn-OE cells were mainly enriched in inflammatory response and innate immune response. In Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, the downregulated genes were mainly enriched in TNF signaling pathway and cytokine-mediated signaling pathways.

CONCLUSIONS

Our findings showed that upregulation of Fasn may play a critical role in islet cell immunmetabolism via modifications of immune/inflammatory related genes on transcription and alternative splicing level, which provide novel insights into characterizing the function of Fasn in islet cell immunity and for the development of chemo/immune therapies.

Diterpenoids from Streptomyces: Structures, Biosyntheses and Bioactivities

Bacteria, especially Streptomyces spp., have been emerging as rich sources of natural diterpenoids with diverse structures and broad bioactivities. Here, we review diterpenoids biosynthesized by Streptomyces , with an emphasis on their structures, biosyntheses, and bioactivities. Although diterpenoids from Streptomyces are relatively rare compared to those from plants and fungi, their novel skeletons, biosyntheses and bioactivities present opportunities for discovering new drugs, enzyme mechanisms, and applications in bio-catalysis and metabolic pathway engineering.

Barley Sprout Water Extract and Saponarin Mitigate Triacylglycerol Accumulation in 3T3-L1 Adipocytes

The mechanisms of action responsible for the reported hypolipidemic activity of barley sprouts have yet to be elucidated. The objective of this study was to compare the content of saponarin (the sole flavonoid present in barley sprout leaves), hypolipidemic activity between barley sprout water extract (BSW) and barley sprout ethanol extract (BSE), and the associated relevance to hypolipidemic activity in 3T3-L1 preadipocytes. BSW elicited superior antiadipogenic effects when compared with BSE in MDI mixture [IBMX 0.5 mM + dexamethasone 1 μM + insulin 1 μg/mL]-treated 3T3-L1 preadipocytes. BSW attenuated MDI-mediated triacylglycerol (TAG) accumulation by inhibiting fatty acid synthase (FAS). FAS protein expression was markedly and dose dependently attenuated by BSW, with higher doses suppressing expression to a level equivalent to the controls. BSW also significantly attenuated MDI-mediated increases in the expression of genes involved in TAG synthesis as well as FAS in 3T3-L1 preadipocytes. High-performance liquid chromatography analysis indicated that BSW contains more than four times more saponarin than BSE. Further investigation of saponarin-mediated hypotriacylglycerolemic activity and related gene expression revealed that saponarin significantly inhibited TAG accumulation, which was attributed to reductions in TAG synthesis-related gene expression. Taken together, these findings provide a basis for further development of barley sprout extract for functional health food purposes.

Fatty Acid Synthase Inhibitor Platensimycin Intervenes the Development of Nonalcoholic Fatty Liver Disease in a Mouse Model

Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disease affecting about 25% of world population, while there are still no approved targeted therapies. Although platensimycin (PTM) was first discovered to be a broad-spectrum antibiotic, it was also effective against type II diabetes in animal models due to its ability to inhibit both bacterial and mammalian fatty acid synthases (FASN). Herein, we report the pharmacological effect and potential mode of action of PTM against NAFLD in a Western diet/CCI₄-induced mouse model and a free fatty acids (FFAs)-induced HepG2 cell model. The proper dose of PTM and its liposome-based nano-formulations not only significantly attenuated the Western diet-induced weight gain and the levels of plasma total triglycerides and glucose, but reduced liver steatosis in mice according to histological analyses. Western blotting analysis showed a reduced protein level of FASN in the mouse liver, suggesting that PTM intervened in the development of NAFLD through FASN inhibition. PTM reduced both the protein and mRNA levels of FASN in FFAs-induced HepG2 cells, as well as the expression of several key proteins in lipogenesis, including sterol regulatory element binding protein-1, acetyl-CoA carboxylase, and stearoyl-CoA desaturase. The expression of lipid oxidation-related genes, including peroxisome proliferator activated receptor α and acyl-CoA oxidase 1, was significantly elevated. In conclusion, our study supports the reposition of PTM to intervene in NAFLD progression, since it could effectively inhibit de novo lipogenesis.

Cutting Edge: Intestinal IL-17A Receptor Signaling Specifically Regulates High-Fat Diet-Mediated, Microbiota-Driven Metabolic Disorders

Previous studies indicate that IL-17A plays an important role in mediating the intestinal microbiota and systemic metabolic functions. However, it is not known where IL-17RA signaling occurs to mediate these effects. To investigate this question, we used intestinal epithelial-specific (Il17ra ^ΔIEC ) and liver-specific (Il17ra^ΔLiver ) IL-17RA knockout mice as well as littermate control mice. Our results indicate that intestinal IL-17RA signaling helps mediate systemic metabolic functions upon exposure to prolonged high-fat diet. Il17ra ^ΔIEC mice display impaired glucose metabolism, altered hormone and adipokine levels, increased visceral adiposity, and greater hepatic lipid deposition when compared with their littermate controls. We show that IL-17RA-driven changes in microbiota composition are responsible for regulating systemic glucose metabolism. Altogether, our data elucidate the importance of intestinal IL-17RA signaling in regulating high-fat diet-mediated systemic glucose and lipid metabolism.

Inhibition of Atherosclerosis and Liver Steatosis by Agmatine in Western Diet-Fed apoE-Knockout Mice Is Associated with Decrease in Hepatic De Novo Lipogenesis and Reduction in Plasma Triglyceride/High-Density Lipoprotein Cholesterol Ratio

Atherosclerosis and NAFLD are the leading causes of death worldwide. The hallmark of NAFLD is triglyceride accumulation caused by an imbalance between lipogenesis de novo and fatty acid oxidation. Agmatine, an endogenous metabolite of arginine, exerts a protective effect on mitochondria and can modulate fatty acid metabolism. In the present study, we investigate the influence of agmatine on the progression of atherosclerotic lesions and the development of hepatic steatosis in apoE^−/− mice fed with a Western high-fat diet, with a particular focus on its effects on the DNL pathway in the liver. We have proved that treatment of agmatine inhibits the progression of atherosclerosis and attenuates hepatic steatosis in apoE^−/− mice on a Western diet. Such effects are associated with decreased total macrophage content in atherosclerotic plaque as well as a decrease in the TG levels and the TG/HDL ratio in plasma. Agmatine also reduced TG accumulation in the liver and decreased the expression of hepatic genes and proteins involved in lipogenesis de novo such as SREBP-1c, FASN and SCD1. In conclusion, agmatine may present therapeutic potential for the treatment of atherosclerosis and fatty liver disease. However, an exact understanding of the mechanisms of the advantageous actions of agmatine requires further study.

Review on target domains and natural compound-based inhibitors of fatty acid synthase for anticancer drug discovery

Cancer cells require a higher amount of energy in the form of fatty acids for their uncontrolled proliferation and growth. Fatty acid synthase (FASN) plays a crucial role in the synthesis of palmitate, which is involved in most of the critical malignant pathways. Hence, by targeting FASN, tumour growth can be controlled. By designing and developing FASN inhibitors with catalytic domain specificity, safe and potential anticancer drugs can be achieved. The article draws light towards the catalytic domains of FASN, their active site residues and interaction of some of the reported natural FASN inhibitors (resveratrol, lavandulyl flavonoids, catechins, stilbene derivatives, etc). The rationality (structure-activity relationship) behind the variation in the activity of the reported natural FASN inhibitors (butyrolactones, polyphenolics, galloyl esters and thiolactomycins) has also been covered. Selective, safe and potentially active FASN inhibitors could be developed by: (i) having proper understanding of the function of all catalytic domains of FASN (ii) studying the upstream and downstream FASN regulators (iii) identifying cancer-specific FASN biomarkers (that are non-essential/absent in the normal healthy cells) (iv) exploring the complete protein structure of FASN, e-screening of the compounds prior to synthesis and study their ADME properties (v) predicting the selectivity based on their strong affinity at the catalytic site of FASN.

Metabolic-associated fatty liver disease and lipoprotein metabolism

BACKGROUND

Non-alcoholic fatty liver disease, or as recently proposed 'metabolic-associated fatty liver disease' (MAFLD), is characterized by pathological accumulation of triglycerides and other lipids in hepatocytes. This common disease can progress from simple steatosis to steatohepatitis, and eventually end-stage liver diseases. MAFLD is closely related to disturbances in systemic energy metabolism, including insulin resistance and atherogenic dyslipidemia.

SCOPE OF REVIEW

The liver is the central organ in lipid metabolism by secreting very low density lipoproteins (VLDL) and, on the other hand, by internalizing fatty acids and lipoproteins. This review article discusses recent research addressing hepatic lipid synthesis, VLDL production, and lipoprotein internalization as well as the lipid exchange between adipose tissue and the liver in the context of MAFLD.

MAJOR CONCLUSIONS

Liver steatosis in MAFLD is triggered by excessive hepatic triglyceride synthesis utilizing fatty acids derived from white adipose tissue (WAT), de novo lipogenesis (DNL) and endocytosed remnants of triglyceride-rich lipoproteins. In consequence of high hepatic lipid content, VLDL secretion is enhanced, which is the primary cause of complex dyslipidemia typical for subjects with MAFLD. Interventions reducing VLDL secretory capacity attenuate dyslipidemia while they exacerbate MAFLD, indicating that the balance of lipid storage versus secretion in hepatocytes is a critical parameter determining disease outcome. Proof of concept studies have shown that promoting lipid storage and energy combustion in adipose tissues reduces hepatic lipid load and thus ameliorates MAFLD. Moreover, hepatocellular triglyceride synthesis from DNL and WAT-derived fatty acids can be targeted to treat MAFLD. However, more research is needed to understand how individual transporters, enzymes, and their isoforms affect steatosis and dyslipidemia in vivo, and whether these two aspects of MAFLD can be selectively treated. Processing of cholesterol-enriched lipoproteins appears less important for steatosis. It may, however, modulate inflammation and consequently MAFLD progression.

Emerging therapeutic approaches for the treatment of NAFLD and type 2 diabetes mellitus

Non-alcoholic fatty liver disease (NAFLD) has emerged as the most prevalent liver disease in the world, yet there are still no approved pharmacological therapies to prevent or treat this condition. NAFLD encompasses a spectrum of severity, ranging from simple steatosis to non-alcoholic steatohepatitis (NASH). Although NASH is linked to an increased risk of hepatocellular carcinoma and cirrhosis and has now become the leading cause of liver failure-related transplantation, the majority of patients with NASH will ultimately die as a result of complications of type 2 diabetes mellitus (T2DM) and cardiometabolic diseases. Importantly, NAFLD is closely linked to obesity and tightly interrelated with insulin resistance and T2DM. Thus, targeting these interconnected conditions and taking a holistic attitude to the treatment of metabolic disease could prove to be a very beneficial approach. This Review will explore the latest relevant literature and discuss the ongoing therapeutic options for NAFLD focused on targeting intermediary metabolism, insulin resistance and T2DM to remedy the global health burden of these diseases.

Animal Fatty Acid Synthase: A Chemical Nanofactory

Fatty acids are crucial molecules for most living beings, very well spread and conserved across species. These molecules play a role in energy storage, cell membrane architecture, and cell signaling, the latter through their derivative metabolites. De novo synthesis of fatty acids is a complex chemical process that can be achieved either by a metabolic pathway built by a sequence of individual enzymes, such as in most bacteria, or by a single, large multi-enzyme, which incorporates all the chemical capabilities of the metabolic pathway, such as in animals and fungi, and in some bacteria. Here we focus on the multi-enzymes, specifically in the animal fatty acid synthase (FAS). We start by providing a historical overview of this vast field of research. We follow by describing the extraordinary architecture of animal FAS, a homodimeric multi-enzyme with seven different active sites per dimer, including a carrier protein that carries the intermediates from one active site to the next. We then delve into this multi-enzyme's detailed chemistry and critically discuss the current knowledge on the chemical mechanism of each of the steps necessary to synthesize a single fatty acid molecule with atomic detail. In line with this, we discuss the potential and achieved FAS applications in biotechnology, as biosynthetic machines, and compare them with their homologous polyketide synthases, which are also finding wide applications in the same field. Finally, we discuss some open questions on the architecture of FAS, such as their peculiar substrate-shuttling arm, and describe possible reasons for the emergence of large megasynthases during evolution, questions that have fascinated biochemists from long ago but are still far from answered and understood.

Bacterial terpenome

Covering: up to mid-2020 Terpenoids, also called isoprenoids, are the largest and most structurally diverse family of natural products. Found in all domains of life, there are over 80 000 known compounds. The majority of characterized terpenoids, which include some of the most well known, pharmaceutically relevant, and commercially valuable natural products, are produced by plants and fungi. Comparatively, terpenoids of bacterial origin are rare. This is counter-intuitive to the fact that recent microbial genomics revealed that almost all bacteria have the biosynthetic potential to create the C5 building blocks necessary for terpenoid biosynthesis. In this review, we catalogue terpenoids produced by bacteria. We collected 1062 natural products, consisting of both primary and secondary metabolites, and classified them into two major families and 55 distinct subfamilies. To highlight the structural and chemical space of bacterial terpenoids, we discuss their structures, biosynthesis, and biological activities. Although the bacterial terpenome is relatively small, it presents a fascinating dichotomy for future research. Similarities between bacterial and non-bacterial terpenoids and their biosynthetic pathways provides alternative model systems for detailed characterization while the abundance of novel skeletons, biosynthetic pathways, and bioactivies presents new opportunities for drug discovery, genome mining, and enzymology.

Proton pump inhibitors suppress DNA damage repair and sensitize treatment resistance in breast cancer by targeting fatty acid synthase

Human fatty acid synthase (FASN) is the sole cytosolic enzyme responsible for de novo lipid synthesis. FASN is essential for cancer cell survival and contributes to drug and radiation resistance by up-regulating DNA damage repair but not required for most non-lipogenic tissues. Thus, FASN is an attractive target for drug discovery. However, despite decades of effort in targeting FASN, no FASN inhibitors have been approved due to poor pharmacokinetics or toxicities. Here, we show that the FDA-approved proton pump inhibitors (PPIs) effectively inhibit FASN and suppress breast cancer cell survival. PPI inhibition of FASN leads to suppression of non-homologous end joining repair of DNA damages by reducing FASN-mediated PARP1 expression, resulting in apoptosis from oxidative DNA damages and sensitization of cellular resistance to doxorubicin and ionizing radiation. Mining electronic medical records of 6754 breast cancer patients showed that PPI usage significantly increased overall survival and reduced disease recurrence of these patients. Hence, PPIs may be repurposed as anticancer drugs for breast cancer treatments by targeting FASN to overcome drug and radiation resistance.

Rapid, Selective, and Sensitive Method for Semitargeted Discovery of Congeneric Natural Products by Liquid Chromatography Tandem Mass Spectrometry

Natural product congeners serve a useful role in the understanding of natural product biosynthesis and structure-activity relationships. A minor congener with superior activity, selectivity, and modifiable functional groups could serve as a more effective lead structure and replace even the original lead molecule that was used for medicinal chemistry modifications. Currently, no effective method exists to discover targeted congeners rapidly, specifically, and selectively from producing sources. Herein, a new method based on liquid-chromatography tandem-mass spectrometry combination is evaluated for targeted discovery of congeners of platensimycin and platencin from the extracts of Streptomyces platensis. By utilizing a precursor-ion searching protocol, tandem mass spectrometry not only confirmed the presence of known congeners but also provided unambiguous detection of many previously unknown congeners of platensimycin and platencin. This high-throughput and quantitative method can be rapidly and broadly applied for dereplication and congener discovery from a variety of producing sources, even when the targeted compounds are obscured by the presence of unrelated natural products.

Ascending dorsal column sensory neurons respond to spinal cord injury and downregulate genes related to lipid metabolism

Regeneration failure after spinal cord injury (SCI) results in part from the lack of a pro-regenerative response in injured neurons, but the response to SCI has not been examined specifically in injured sensory neurons. Using RNA sequencing of dorsal root ganglion, we determined that thoracic SCI elicits a transcriptional response distinct from sciatic nerve injury (SNI). Both SNI and SCI induced upregulation of ATF3 and Jun, yet this response failed to promote growth in sensory neurons after SCI. RNA sequencing of purified sensory neurons one and three days after injury revealed that unlike SNI, the SCI response is not sustained. Both SCI and SNI elicited the expression of ATF3 target genes, with very little overlap between conditions. Pathway analysis of differentially expressed ATF3 target genes revealed that fatty acid biosynthesis and terpenoid backbone synthesis were downregulated after SCI but not SNI. Pharmacologic inhibition of fatty acid synthase, the enzyme generating palmitic acid, decreased axon growth and regeneration in vitro. These results support the notion that decreased expression of lipid metabolism-related genes after SCI, including fatty acid synthase, may restrict axon regenerative capacity after SCI.

Fatty Acid Synthase Inhibitor TVB-2640 Reduces Hepatic de Novo Lipogenesis in Males With Metabolic Abnormalities

BACKGROUND AND AIMS

Elevated hepatic de novo lipogenesis (DNL) is a key distinguishing characteristic of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis. In rodent models of NAFLD, treatment with a surrogate of TVB-2640, a pharmacological fatty acid synthase inhibitor, has been shown to reduce hepatic fat and other biomarkers of DNL. The purpose of this phase I clinical study was to test the effect of the TVB-2640 in obese men with certain metabolic abnormalities that put them at risk for NAFLD.

APPROACH AND RESULTS

Twelve subjects (mean ± SEM, 42 ± 2 years, body mass index 37.4 ± 1.2 kg/m² , glucose 103 ± 2 mg/dL, triacylglycerols 196 ± 27 mg/dL, and elevated liver enzymes) underwent 10 days of treatment with TVB-2640 at doses ranging from 50-150 mg/day. Food intake was controlled throughout the study. Hepatic DNL was measured before and after an oral fructose/glucose bolus using isotopic labeling with 1-¹³ C₁ -acetate intravenous infusion, followed by measurement of labeled very low-density lipoprotein palmitate via gas chromatography mass spectometry. Substrate oxidation was measured by indirect calorimetry. Across the range of doses, fasting DNL was reduced by up to 90% (P = 0.003). Increasing plasma concentrations of TVB-2640 were associated with progressive reductions in the percent of fructose-stimulated peak fractional DNL (R²  = -0.749, P = 0.0003) and absolute DNL area under the curve 6 hours following fructose/glucose bolus (R²  = -0.554, P = 0.005). For all subjects combined, alanine aminotransferase was reduced by 15.8 ± 8.4% (P = 0.05). Substrate oxidation was unchanged, and safety monitoring revealed that the drug was well tolerated, without an increase in plasma triglycerides. Alopecia occurred in 2 subjects (reversed after stopping the drug), but otherwise no changes were observed in fasting glucose, insulin, ketones, and renal function.

CONCLUSION

These data support the therapeutic potential of a fatty acid synthase inhibitor, TVB-2640 in particular, in patients with NAFLD and nonalcoholic steatohepatitis.

Evaluation of FASN inhibitors by a versatile toolkit reveals differences in pharmacology between human and rodent FASN preparations and in antiproliferative efficacy in vitro vs. in situ in human cancer cells

De novo synthesis of fatty acids is essential to maintain intensive proliferation of cancer cells. Unlike normal cells that utilize food-derived circulating lipids for their fuel, cancer cells rely on heightened lipogenesis irrespective of exogenous lipid availability. Overexpression and activity of the multidomain enzyme fatty acid synthase (FASN) is crucial in supplying palmitate for protumorigenic activity. Therefore, FASN has been proposed as an attractive target for drug development. As an effort to set up an effective toolkit to study FASN inhibitors in human and rodent tissues, we validated activity-based protein profiling (ABPP) as a viable approach to unveil inhibitors targeting FASN thioesterase domain (FASN-TE). ABPP was combined with multi-well plate-assays designed for classical substrate-based FASN activity analysis together with powerful monitoring of cancer cell proliferation using IncuCyte® Live Cell Analyzing System. FASN-TE inhibitors were identified by competitive ABPP using HEK293 cell lysates in a screen of in-house compounds (200+) designed to target serine hydrolase (SH) family. The identified compounds were tested for their inhibitor potencies in vitro using a substrate-based activity assay monitoring FASN-dependent NADPH consumption in LNCaP prostate cancer cell preparation, in parallel with selected reference inhibitors, including orlistat (THL), GSK2194069, GSK837149A, platensimycin and BI-99179. LNCaP lysate supernatant was validated as a reliable native preparation to monitor FASN-dependent NADPH consumption as opposed to human glioma GAMG cells, whereas FASN enrichment was a prerequisite for accurate assays. While inhibitor pharmacology was identical between human prostate and glioma cancer cell FASN preparations, notable differences were revealed between human and rodent FASN preparations, especially for inhibitors targeting FASN-TE. ABPP combined with substrate-based assays facilitated identification of pan thiol-reactive inhibitor scaffolds, exemplified by the 1,2,4-thiadiazole moiety. Finally, selected compounds were evaluated for their antiproliferative efficacy in situ using GAMG cells. These studies revealed that while the tested compounds acted as potent FASN inhibitors in vitro, only a few showed antiproliferative efficacy in situ. To conclude, we describe a versatile toolkit to study FASN inhibitors in vitro and in situ using human cancer cells and reveal dramatic pharmacological differences between human and rodent FASN preparations.

Molecular and Pathological Events Involved in the Pathogenesis of Diabetes-Associated Nonalcoholic Fatty Liver Disease

Diabetes mellitus is a rising epidemic in most part of the world and is often associated with multiple organ disorders such as kidney, liver, and cardiovascular diseases. Liver is a major metabolic hub, and the metabolic disorders associated with diabetes result in liver dysfunctions culminating in spectrum of liver diseases such as fatty liver disorders, cirrhosis, and hepatocellular carcinoma. The intervention strategies to prevent diabetes-associated liver injury require an overall understanding of the key factors and molecular pathways which can be strategically targeted. The present review focuses on some of the key aspects of fatty acid metabolism, fetuin-A regulation, inflammatory pathways, and genetic factors associated with insulin resistance, dyslipidemia, hyperglycemia, oxidative stress, and so on involved in the nexus between diabetes and liver injury. Further recent interventions, pharmacological target, and newer therapeutic agents are discussed briefly for the better clinical management of diabetes-associated hepatic disorders.

Alterations in the Transcriptional Profile of the Liver Tissue and the Therapeutic Effects of Propolis Extracts in Alcohol-induced Steatosis in Rats

The hepatoprotective effects of the ethanolic extracts of propolis (EEP) on alcohol-induced liver steatosis were investigated in Wistar rats. Chronic alcoholic fatty liver was induced by administration of 52% alcohol to male Wistar rats at the dose of 1% body weight for 7 weeks. Then animals were simultaneously treated with 50% ethanol solutions of EEP or normal saline at the dose of 0.1% body weight for 4 further weeks. Serological analyses and liver histopathology studies were performed to investigate the development of steatosis. Microarray analysis was conducted to investigate the alterations of hepatic gene expression profiling. Our results showed that 4-week treatment of EEP helped to restore the levels of various blood indices, liver function enzymes and the histopathology of liver tissue to normal levels. Results from the microarray analysis revealed that the hepatic expressions of genes involved in lipogenesis were significantly down-regulated by EEP treatment, while the transcriptional expressions of functional genes participating in fatty acids oxidation were markedly increased. The ability of EEP to reduce the negative effects of alcohol on liver makes propolis a potential natural product for the alternative treatment of alcoholic fatty liver.

Bacterial Diterpene Biosynthesis

This Minireview summarises recent developments in the biosynthesis of diterpenes by diterpene synthases in bacteria. It is structured by the class of enzyme involved in the first committed step towards diterpenes, starting with type I diterpene synthases, followed by type II enzymes and the more recently discovered UbiA-related diterpene synthases. A special emphasis lies on the reaction mechanisms of diterpene synthases that convert simple linear precursors through cationic cascades into structurally complex, usually polycyclic carbon skeletons with multiple stereogenic centres. A further main focus of this Minireview is a discussion of how these mechanisms can be unravelled. Downstream modifications to bioactive molecules are also covered.

Circulating serum fatty acid synthase is elevated in patients with diabetes and carotid artery stenosis and is LDL-associated

BACKGROUND AND AIMS

Diabetes is an independent risk factor for carotid artery stenosis (CAS). Fatty acid synthase (FAS), an essential de novo lipogenesis enzyme, has increased activity in the setting of diabetes that leads to altered lipid metabolism. Circulating FAS (cFAS) was recently observed in the blood of patients with hyperinsulinemia and cancer. We thought to evaluate the origin of cFAS and its role in diabetes-associated CAS.

METHODS

Patients with diabetes and no diabetes, undergoing carotid endarterectomy (CEA) for CAS, were prospectively enrolled for collection of plaque and fasting serum. FPLC was used to purify lipoprotein fractions, and ELISA was used to quantify cFAS content and activity. Immunoprecipitation (IP) was used to evaluate the affinity of cFAS to LDL-ApoB.

RESULTS

Patients with CAS had higher cFAS activity (p < 0.01), and patients with diabetes had higher cFAS activity than patients with no diabetes (p < 0.05). cFAS activity correlated with serum glucose (p = 0.03, r² = 0.35), and cFAS content trended with plaque FAS content (p = 0.06, r² = 0.69). cFAS was predominantly in LDL cholesterol fractions of patients with CAS (p < 0.001), and IP of cFAS demonstrated pulldown of ApoB. Similar to patients with diabetes, db/db mice had highest levels of serum cFAS (p < 0.01), and fasL^-/- (tissue-specific liver knockdown of FAS) mice had the lowest levels of cFAS (p < 0.001).

CONCLUSIONS

Serum cFAS is higher in patients with diabetes and CAS, appears to originate from the liver, and is LDL cholesterol associated. We postulate that LDL may be serving as a carrier for cFAS that contributes to atheroprogression in carotid arteries of patients with diabetes.

Treatment with an inhibitor of fatty acid synthase attenuates bone loss in ovariectomized mice

Bone and fat cells have an antagonistic relationship. Adipocytes exert a toxic effect on bone cells in vitro through the secretion of fatty acids, which are synthesized by fatty acid synthase (FAS). Inhibition of FAS in vitro rescues osteoblasts from fat-induced toxicity and cell death. In this study, we hypothesized that FAS inhibition would mitigate the loss of bone mass in ovariectomized (OVX) mice. We treated OVX C57BL/6 mice with cerulenin (a known inhibitor of FAS) for 6 weeks and compared their bone phenotype with vehicle-treated controls. Cerulenin-treated mice exhibited a significant decrease in body weight, triglycerides, leptin, and marrow and subcutaneous fat without changes in serum glucose or calciotropic hormones. These effects were associated with attenuation of bone loss and normalization of the bone phenotype in the cerulenin-treated OVX group compared to the vehicle-treated OVX group. Our results demonstrate that inhibition of FAS enhances bone formation, induces uncoupling between osteoblasts and osteoclasts, and favors mineralization, thus providing evidence that inhibition of FAS could constitute a new anabolic therapy for osteoporosis.

Targeted antibiotic discovery through biosynthesis-associated resistance determinants: target directed genome mining

Intense competition between microbes in the environment has directed the evolution of antibiotic production in bacteria. Humans have harnessed these natural molecules for medicinal purposes, magnifying them from environmental concentrations to industrial scale. This increased exposure to antibiotics has amplified antibiotic resistance across bacteria, spurring a global antimicrobial crisis and a search for antibiotics with new modes of action. Genetic insights into these antibiotic-producing microbes reveal that they have evolved several resistance strategies to avoid self-toxicity, including product modification, substrate transport and binding, and target duplication or modification. Of these mechanisms, target duplication or modification will be highlighted in this review, as it uniquely links an antibiotic to its mode of action. We will further discuss and propose a strategy to mine microbial genomes for these genes and their associated biosynthetic gene clusters to discover novel antibiotics using target directed genome mining.

The Structures and Bioactivities of Fatty Acid Synthase Inhibitors

Background:

Fatty Acid Synthase (FAS or FASN) is a vital enzyme which catalyzes the de novo synthesis of long chain fatty acids. A number of studies have recently been reported that FAS was combined targets for the discovery of anti-obesity and anti-cancer drugs. Great interest has been developed in finding novel FAS inhibitors, and result in more than 200 inhibitors being reported.

Methods:

The reported research literature about the FAS inhibitors was collected and analyzedsised through major databases including Web of Science, and PubMed. Then the chemical stractures, FAS inhibitory activities, and Structure-Activity Relationships (SAR) were summarized focused on all these reported FAS inhibitors.

Results:

The 248 FAS inhibitors, which were reported during the past 20 years, could be divided into thiolactone, butyrolactone and butyrolactam, polyphenols, alkaloids, terpenoids, and other structures, in view of their structure characteristics. And the SAR of high inhibitory structures of each type was proposed in this paper.

Conclusion:

A series of synthetic quinolinone derivatives show strongest inhibitory activity in the reported FAS inhibitors. Natural polyphenols, existing in food and herbs, show more adaptive in medicine exploration because of their safety and efficiency. Moreover, screening the FAS inhibitors from microorganism and marine natural products could be the hot research directions in the future.

Ellagic acid ameliorates AKT-driven hepatic steatosis in mice by suppressing de novo lipogenesis via the AKT/SREBP-1/FASN pathway

Ellagic acid alleviates hepatic lipid accumulation in mice by suppressing AKT-driven de novo lipogenesis.

Targeting Metabolism, Insulin Resistance, and Diabetes to Treat Nonalcoholic Steatohepatitis

Obesity, insulin resistance, and diabetes are strongly linked to the accumulation of excessive lipids in the liver parenchyma, a condition known as nonalcoholic fatty liver disease (NAFLD). Given its association with obesity and related metabolic diseases, it is not surprising that the prevalence of NAFLD has dramatically increased in the past few decades. NAFLD has become the most common liver disease in many areas of the world. The term, NAFLD, encompasses a spectrum of disorders that ranges from simple steatosis to steatosis with inflammatory lesions (nonalcoholic steatohepatitis [NASH]). Although simple steatosis might be relatively benign, epidemiologic studies have linked NASH to greatly increased risk of developing cirrhosis and hepatocellular carcinoma. Yet despite this, there are no approved treatments for the disease, and it remains a significant unmet medical need. This Perspective will review some of the relevant literature on the topic and examine approved and experimental NASH therapeutic concepts that target intermediary metabolism, insulin resistance, and diabetes to treat this emerging public health problem.

Semisynthesis and Biological Evaluation of Platensimycin Analogues with Varying Aminobenzoic Acids

Platensimycin (PTM) is an excellent natural product drug lead against various gram-positive pathogens, including methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci. In this study, twenty PTM derivatives with varying aminobenzoic acids were semisynthesized. In contrast to all the previous reported inactive aminobenzaote analogues, a few of them showed moderate antibacterial activities against S. aureus. Our study suggested that modification of the conserved aminobenzoic acid remains a viable approach to diversify the PTM scaffold.

Repurposing matrine for the treatment of hepatosteatosis and associated disorders in glucose homeostasis in mice

The present study investigated the efficacy of the hepatoprotective drug matrine (Mtr) for its new application for hepatosteatosis and associated disorders in glucose homeostasis. The study was performed in two nutritional models of hepatosteatosis in mice with various abnormal glucose homeostasis: (1) high-fructose diet (HFru) induced hepatosteatosis and glucose intolerance from hepatic, and (2) hepatosteatosis and hyperglycemia induced by high-fat (HF) diet in combination with low doses of streptozotocin (STZ). Administration of Mtr (100 mg/kg every day in diet for 4 weeks) abolished HFru-induced hepatosteatosis and glucose intolerance. These effects were associated with the inhibition of HFru-stimulated de novo lipogenesis (DNL) without altering hepatic fatty acid oxidation. Further investigation revealed that HFru-induced endoplasmic reticulum (ER) stress was inhibited, whereas heat-shock protein 72 (an inducible chaperon protein) was increased by Mtr. In a type 2 diabetic model induced by HF-STZ, Mtr reduced hepatosteatosis and improved attenuated hyperglycemia. The hepatoprotective drug Mtr may be repurposed for the treatment of hepatosteatosis and associated disorders in glucose homeostasis. The inhibition of ER stress associated DNL and fatty acid influx appears to play an important role in these metabolic effects.

Cottonseed protein concentrate (CPC) suppresses immune function in different intestinal segments of hybrid grouper ♀Epinephelus fuscoguttatus×♂Epinephelus lanceolatu via TLR-2/MyD88 signaling pathways

Cottonseed protein concentrate (CPC) has similar amino acid composition compared with fish meal, and has the characteristics of low gossypol and low toxicity. The present study was conducted to investigate the growth performance, antioxidant capacity and different intestinal segments immune responses of hybrid grouper to replacement dietary fish meal ofCPC. Six iso-nitrogenous (50% crude protein) and iso-lipidic (10% crude lipid) diets were formulated: a reference diet (FM) containing 60% fishmeal and five experimental diets (12%, 24%, 36%, 48 and 60%) in which fishmeal protein was substituted at different levels by CPC to feed fish (initial body weight: 11 ± 0.23 g) for 8 weeks. Thena challenge test with injection of Vibrio parahaemolyticus was conducted for 7 days until the fish stabilized. The results showed that specific growth rate (SGR) was the highest with 24% replacement level and feed conversion ratio (FCR)was significantly increased when the replacement level reached 48% (P < 0.05). The content of malonaldehyde (MDA) in the serum was significantly increased when the replacement level reached 36% (P < 0.05). The plica height in the proximal, mid and distal intestine were significantly decreased with the replacement level up to 48% (P < 0.05). Hepatic fat deposition wasaggravatedwhen the replacement level reached 36% (P < 0.05). The expression of IL-6, TNF-α, and IL-1β mRNAs were significantly up-regulated (P < 0.05). The hepcidin mRNA expression was significantly down-regulated (P < 0.05). In proximal intestine (PI) and mid intestine (MI), IFN-γ mRNA expression was significantly up-regulated (P < 0.05). These results suggested that the CPC decreased hybrid grouper growth performance and inflammation function, and different inflammation function responses in PI,MI, and distal intestine (DI) were mediated partly by the TLR-2/MyD88 signaling pathway. According to the analysis of specific growth rate, the dietary optimum replacement level and maximum replacement level were estimated to be 17% and 34%, respectively.

Physiological and molecular study on the anti-obesity effects of pineapple (Ananas comosus) juice in male Wistar rat

The present study was performed to assess anti-obesity effects of raw pineapple juice in high fat diet (HFD)-induced fatness. Based on food type, rats were divided into normal diet and HFD groups. When animals of HFD group become obese, they were given pineapple juice along with either HFD or normal diet. Blood biochemistry, liver and muscle gene expressions were analyzed. HFD induced significant elevations in body weight, body mass index (BMI), body fat accumulation, liver fat deposition and blood lipids while juice restored these parameters near to their normal values. Juice significantly decreased serum insulin and leptin while adiponectin was increased. Juice administration downregulated the increment of FAS and SERBP-1c mRNA expression in liver and upregulated HSL and GLUT-2 expressions. The muscular lipolytic CPT-1 expression was upregulted by juice treatment. Pineapple juice, therefore, may possibly be used as anti-obesity candidate where it decreased lipogenesis and increased lipolysis.

TRAIL reduces impaired glucose tolerance and NAFLD in the high-fat diet fed mouse

Recent studies suggest that a circulating protein called TRAIL (TNF-related apoptosis inducing ligand) may have an important role in the treatment of type 2 diabetes. It has been shown that TRAIL deficiency worsens diabetes and that TRAIL delivery, when it is given before disease onset, slows down its development. The present study aimed at evaluating whether TRAIL had the potential not only to prevent, but also to treat type 2 diabetes. Thirty male C57BL/6J mice were randomized to a standard or a high-fat diet (HFD). After 4 weeks of HFD, mice were further randomized to receive either placebo or TRAIL, which was delivered weekly for 8 weeks. Body weight, food intake, fasting glucose, and insulin were measured at baseline and every 4 weeks. Tolerance tests were performed before drug randomization and at the end of the study. Tissues were collected for further analyses. Parallel in vitro studies were conducted on HepG2 cells and mouse primary hepatocytes. TRAIL significantly reduced body weight, adipocyte hypertrophy, free fatty acid levels, and inflammation. Moreover, it significantly improved impaired glucose tolerance, and ameliorated non-alcoholic fatty liver disease (NAFLD). TRAIL treatment reduced liver fat content by 47% in vivo as well as by 45% in HepG2 cells and by 39% in primary hepatocytes. This was associated with a significant increase in liver peroxisome proliferator-activated receptor (PPAR) γ (PPARγ) co-activator-1 α (PGC-1α) expression both in vivo and in vitro, pointing to a direct protective effect of TRAIL on the liver. The present study confirms the ability of TRAIL to significantly attenuate diet-induced metabolic abnormalities, and it shows for the first time that TRAIL is effective also when administered after disease onset. In addition, our data shed light on TRAIL therapeutic potential not only against impaired glucose tolerance, but also against NAFLD.

Targeting ATP-Citrate Lyase in Hyperlipidemia and Metabolic Disorders

Chronic overnutrition and a sedentary lifestyle promote imbalances in metabolism, often manifesting as risk factors for life-threating diseases such as atherosclerotic cardiovascular disease (ASCVD) and nonalcoholic fatty liver disease (NAFLD). Nucleocytosolic acetyl-coenzyme A (CoA) has emerged as a central signaling node used to coordinate metabolic adaptations in response to a changing nutritional status. ATP-citrate lyase (ACL) is the enzyme primarily responsible for the production of extramitochondrial acetyl-CoA and is thus strategically positioned at the intersection of nutrient catabolism and lipid biosynthesis. Here, we discuss recent findings from preclinical studies, as well as Mendelian and clinical randomized trials, demonstrating the importance of ACL activity in metabolism, and supporting its inhibition as a potential therapeutic approach to treating ASCVD, NAFLD, and other metabolic disorders.