Fatty Acid Oxidation Metabolism Research Articles

Research progress on metabolic reprogramming of innate immune cells involved in immune-regulation of sepsis

Immunosuppression plays a critical role in death of sepsis. Innate immunity is the first line defense to prevent pathogen invasion, and neutrophils, macrophages, dendritic cells and natural killer cells (NK cells) are closely involved in the process of the immune-regulation during sepsis. Recently, metabolic reprogramming in immune cells is known as a keystone for immune intervention therapy in sepsis. Here, we focus on the recent advances in metabolic regulation in neutrophils, macrophages, dendritic cells and NK cells including glycolysis, fatty acid synthesis, fatty acid oxidation and arginine metabolism involved in the immune-regulation of sepsis. This review will be helpful to summarize the mechanisms underlying sepsis-induced immunosuppression.

Clinical Spectrum of Inherited Disorders of Metabolism.

To study the clinical profile and outcome of children with Inborn errors of metabolism. Thirty one newly diagnosed children with Inborn errors of metabolism over a 1 y period were studied for their relevant clinical, biochemical, diagnosis, treatment and follow-up details. Inborn errors of metabolism accounted for 2% of hospital admissions. Sixty five percent were born to parents of consanguineous marriage. Of the 31 children with Inborn errors of metabolism, 16 (51%) had lysosomal storage disorders, 8 (26%) had disorders of amino acid metabolism, 2 (6%) each had disorders of carbohydrate and bile acid metabolism, 1 (3%) each had disorders of fatty acid oxidation, mitochondrial and peroxisome metabolism. Acrodermatitis dysmetabolica, as a complication was observed in one child and the overall mortality rate in this series was 10%. Lysosomal storage disorders constituted the majority of Inborn errors of metabolism in this series and amino acidopathies/organic acidemias were successfully treated with special formulas.

Regulation of Tolerogenic Features on Dexamethasone-Modulated MPLA-Activated Dendritic Cells by MYC.

The potential of tolerogenic dendritic cells (tolDCs) to shape immune responses and restore tolerance has turn them into a promising therapeutic tool for cellular therapies directed toward immune regulation in autoimmunity. Although the cellular mechanisms by which these cells can exert their regulatory function are well-known, the mechanisms driving their differentiation and function are still poorly known, and the variety of stimuli and protocols applied to differentiate DCs toward a tolerogenic phenotype makes it even more complex to underpin the molecular features involved in their function. Through transcriptional profiling analysis of monocyte-derived tolDCs modulated with dexamethasone (Dex) and activated with monophosphoryl lipid A (MPLA), known as DM-DCs, we were able to identify MYC as one of the transcriptional regulators of several genes differentially expressed on DM-DCs compared to MPLA-matured DCs (M-DCs) and untreated/immature DCs (DCs) as revealed by Ingenuity Pathway Analysis (IPA) upstream regulators evaluation. Additionally, MYC was also amidst the most upregulated genes in DM-DCs, finding that was confirmed at a transcriptional as well as at a protein level. Blockade of transactivation of MYC target genes led to the downregulation of tolerance-related markers IDO1 and JAG1. MYC blockade also led to downregulation of PLZF and STAT3, transcription factors associated with immune regulation and inhibition of DC maturation, further supporting a role of MYC as an upstream regulator contributing to the regulatory phenotype of DM-DCs. On the other hand, we had previously shown that fatty acid oxidation, oxidative metabolism and zinc homeostasis are amongst the main biological functions represented in DM-DCs, and here we show that DM-DCs exhibit higher intracellular expression of ROS and Zinc compared to mature M-DCs and DCs. Taken together, these findings suggest that the regulatory profile of DM-DCs is partly shaped by the effect of the transcriptional regulation of tolerance-inducing genes by MYC and the modulation of oxidative metabolic processes and signaling mediators such as Zinc and ROS.

Novel Dual PPARα/δ Agonist F3SM Increased Oxidative Muscle Fiber and Ameliorated Metabolic Disorders in Non‐trained Mice

OBJECTIVESedentary lifestyle and over‐nutrition are the underlying driving forces behind the development of metabolic diseases, particularly diabetes, dyslipidemia, obesity, etc. Physical inactivity reduced proportion of oxidative muscle fibers, and is associated with these metabolic dysfunctions. PPARβ/δ is the targeted nuclear receptor directly responsible for reprogramming the fiber‐specific contractile, links muscle fiber type to energy metabolism. PPARα activation contributes to hepatic fatty acid oxidation and lipid metabolism. Here we tested if moderate PPARα/β activation is a feasible substitute therapeutic strategy to sedentary lifestyle related metabolic disorders.METHODSWe used a combination of virtual docking, SPR‐based binding, luciferase reporter and target gene transcriptional assays to analyze the interaction mode, affinity and agonistic activity of F3SM to PPAR in vitro, respectively. With reference to exercise, the impact of F3SM on muscle endurance and strength were comparatively studied in normal mice. Serum metabolomics study was used to analyse the overall metabolic alterations. And the insulin sensitizing and anti‐dyslipidemia effects of F3SM were examined in high‐diet‐induced (HFD) obesity mice.RESULTSF3SM interacted with PPARα/β‐LBD, showed specific binding with PPARα/β, displayed potent PPARδ agonism (EC50 1.37 ± 0.33nM) and accompanied by a relative weaker PPARα agonism (EC50 75.18 ± 1.88nM), but without PPARγ activation. Target gene expression assay confirmed transcriptional activation of PPARα and PPARβ by F3SM respectively in the target tissues. Similar to exercise training, F3SM enhanced the running capability of normal mice in a dose‐dependent manner and increased the proportion of oxidative skeletal muscle fibers. Correspondingly, F3SM treated muscle was also confirmed to be fatigue‐resistant. Furthermore, serum fatty acid metabolism and whole serum metabolism disclosed the levels of intermediate metabolites and key enzymes in fatty acid oxidation pathways were increased following F3SM treatment. Thus serum unsaturated fatty acid levels, especially polyunsaturated fatty acids were raised. More importantly, F3SM indeed was capable of ameliorating glucose intolerance and hyperlipidemia in the HFD mice. In consistent with this, F3SM significantly promoted the uptake of fatty acids into hepatocytes in a dose‐dependent and insulin‐independent manner.CONCLUSIONSDual PPARα/β activation by F3SM increases the proportion of oxidative muscle fibres and switches the energy source to enhanced utilization of fatty acids. Moderate PPARα/β activation could replicate the metabolic benefits of exercise training and may be a promising strategy in combating sedentary lifestyle related metabolic diseases.Support or Funding InformationNational Science and Technology Major Project(2012ZX09301‐003), National Natural Science Foundation of China (81430090, 81773790)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Chinese medicine Jinlida granules improve high-fat-diet induced metabolic disorders via activation of brown adipose tissue in mice

AimsActivation of brown adipose tissue (BAT) thermogenesis could contribute to energy expenditure, which is critical for the treatment of obesity and type 2 diabetes mellitus (T2DM). In the present study, we aimed to systematically investigate whether traditional Chinese medication Jinlida (JLD) granules could improve metabolic disorders and activate BAT thermogenesis in C57BL/6 J mice fed with a high-fat diet (HFD). MethodsIn the present study, JLD (3.8 g/kg) in 0.5% of carboxymethyl cellulose (CMC) solution was administrated daily by oral gavage to HFD-induced mice for 15 weeks. The body weight, biochemical analysis, histology analysis, intraperitoneal glucose and insulin tolerance (OGTT and ITT) tests were measured to explore metabolic disorders. Cold tolerance test, real-time PCR (qRT-PCR), immunohistochemistry, and western blot were performed to evaluate BAT function. ResultsAs results, JLD treatment significantly ameliorated HFD-induced obesity and fat mass gain, maintained glucose and lipid homeostasis, and improved hepatic steatosis and inflammation. More importantly, we observed that JLD markedly activated BAT thermogenesis in HFD-induced obese mice. Moreover, our data confirmed that JLD promoted mitochondrial biogenesis and fatty acid oxidation metabolism in BAT. ConclusionsThese data suggested that JLD could improve metabolic disorders in associated with activation of BAT thermogenesis via enhancement of mitochondrial biogenesis and fatty acid oxidation metabolism, thus providing a new pharmacological evidence for the clinical usage of JLD in T2DM treatment.

The enhancing effect of Acanthopanax sessiliflorus fruit extract on the antibacterial activity of porcine alveolar 3D4/31 macrophages via NF-κB1 and lipid metabolism regulation.

ObjectiveThe demands for measures to improve disease resistance and productivity of livestock are increasing, as most countries prohibit the addition of antibiotics to feed. This study therefore aimed to uncover functional feed additives to help enhance livestock immunity and disease resistance, using Acanthopanax sessiliflorus fruit extract (ASF).MethodsASF was extracted with 70% EtOH, and total polyphenolic and catechin contents were measured by the Folin-Ciocalteu and vanillin assay, respectively. The 3D4/31 porcine macrophage cells (MΦ) were activated by phorbol 12-myristate 13-acetate (PMA), and cell survival and growth rate were measured with or without ASF treatment. Flow-cytometric analysis determined the lysosomal activity, reactive oxygen species levels (ROS), and cell cycle distribution. Nuclear factor kappa B (NF-κB) and superoxide dismutase (SOD) protein expression levels were quantified by western blotting and densitometry analysis. Quantitative polymerase chain reaction was applied to measure the lipid metabolism-related genes expression level. Lastly, the antibacterial activity of 3D4/31 MΦ cells was evaluated by the colony forming unit assay.ResultsASF upregulated the cell viability and growth rate of 3D4/31 MΦ, with or without PMA activation. Moreover, lysosomal activity and intracellular ROS levels were increased after ASF exposure. In addition, the antioxidant enzyme SOD2 expression levels were proportionately increased with ROS levels. Both ASF and PMA treatment resulted in upregulation of NF-κB protein, tumor necrosis factor (TNF)α mRNA expression levels, lipid synthesis, and fatty acid oxidation metabolism. Interestingly, co-treatment of ASF with PMA resulted in recovery of NF-κB, TNFα, and lipid metabolism levels. Finally, ASF pretreatment enhanced the in vitro bactericidal activity of 3D4/31 MΦ against Escherichia coli.ConclusionThis study provides a novel insight into the regulation of NF-κB activity and lipid metabolism in MΦ, and we anticipate that ASF has the potential to be effective as a feed additive to enhance livestock immunity.

P143 HIF1A INHIBITS PRO-INFLAMMATORY CELLULAR PROGRAM IN FOXP3+ CELLS IMPLICATED IN IBD.

A perplexing observation in Crohn’s disease has been the detection of increased numbers of FOXP3+ cells within the lesions, a higher proportion of FOXP3+to CD4+ cells within the mucosa of Crohn’s patients and a significantly higher gene count of FOXP3 from CD4+ cells isolated from lesions. These FOXP3+ cells appear to be unable to suppress inflammation in situ, and their role in disease is poorly understood. We have shown that a majority of FOXP3 gene targets in CD4+ lymphocytes isolated from Crohn’s lesions are in fact significantly upregulated and display a Th1/Th17-like gene set enrichment. These findings are incongruent with FOXP3’s ascribed role as a Treg specific transcriptional repressor. The hypoxia-inducible transcription factor HIF1a is upregulated in Tregs. During physiologic hypoxia experienced in the gut mucosa, the abundant HIF1a levels expressed in FOXP3+ Tregs are not driving aerobic glycolysis, as these cells extensively utilize fatty acid oxidative metabolism for their bioenergetic needs. We present data demonstrating the importance of nuclear HIF1a in inhibiting the FOXP3 activator complex, which leads to pro-inflammatory pathological FOXP3+ cells, and instead promotes the FOXP3 repressor complex, resulting in anti-inflammatory suppressor FOXP3+ cells. FOXP3 complex composition +/- HIF1a or IL-6 was assessed by immuno-precipitation and PLA. FOXP3 gene target promoter histone and histone modifying enzyme status was assessed by ChIP. A FOXP3-cre driven, EZH2fl/fl animal model was utilized to assess FOXP3 activator function/pro-inflammatory phenotype with HIF1a modulation on colitis. The FOXP3/p300 activation complex was more abundant in the absence of HIF1a, whereas the FOXP3/EZH2 repressor complex was reciprocally more abundant in the presence of HIF1a. Furthermore, IL-6 disrupts FOXP3/HIF1a association and the FOXP3/EZH2 repressor complex, resulting in increased FOXP3/p300 complex. Using IFNg and TNFa as a model genes for FOXP3 transcriptional regulation, we demonstrated that HIF1a regulates FOXP3 dependent gene activation by histone modifications at the IFNg and TNFa promoters. We demonstrated that HIF1a restores repression of the master lineage markers TBET and RORgT in in-vitro derived Tregs lacking FOXP3/EZH2 repressor function. Finally, the use of a HIF1a activator rescues colitis through HIF1a stabilization in the FOXP3 driven EZH2 null animals. FOXP3 acts as a binary switch, recruiting repressor complexes, or activator complexes to key Treg gene networks. We demonstrate HIF1a to be a key regulator of the FOXP3 switch mechanism directing program execution towards a repressed or anti-inflammatory state.

The inhibition of Nrf2 accelerates renal lipid deposition through suppressing the ACSL1 expression in obesity-related nephropathy

Background: Obesity has become a worldwide epidemic, and the incidence of obesity is increasing year by year. Obesity-related nephropathy (ORN) is a common kidney complication of obesity. Long-chain acyl-CoA synthetases-1, (ACSL1), is a key enzyme in the oxidative metabolism of fatty acids in mitochondria and ACSL1 may play a direct role in renal lipid deposition and promote the progress of ORN. In this study, we focus on the renoprotective role of ACSL1 in ORN.Methods: Electron microscopy, immunohistochemical (IHC) staining, Western blot, and real-time PCR were used to detect the expression of ACSL1and Nrf2 in ORN patients, ob/ob mice and palmitic acid (PA)-treated HK-2 cells. Oil red staining and Elisa Kit were used to detect the intracellular FFA and TG contents in ob/ob mice and PA-treated HK-2 cells. Dihydroethidium (DHE) staining and the MDA/SOD measurement were used to detect the ROS production. In order to demonstrate the role of ACSL1 and the interaction between ACSL1 and Nrf2 in ORN, related siRNA and plasmid were transfected into HK-2 cells.Results: More ROS production and renal lipid deposition have been found in ORN patients, ob/ob mice and PA-treated HK-2 cells. Compared with control, all the expression of ACSL1and Nrf2 were down-regulated in ORN patients, ob/ob mice and PA-treated HK-2 cells. The Nrf2 could regulate the expression of ACSL1 and the ACSL1 played the direct role in renal lipid deposition.Conclusions: The Nrf2 is inhibited in ORN, resulting more ROS production and oxidative stress. Increased oxidative stress will suppress the expression of ACSL1, which could increase the intracellular FFA and TG contents, ultimately leading to renal lipid deposition in renal tubulars and accelerating the development of ORN.

Changes in selected biochemical parameters during subclinical and clinical ketosis in dairy cows

Negative energy balance (NEB) is a common pathological cause of ketosis. As the major organs of lipid metabolism, the liver and fat tissue take part in regulating lipid oxidative capacity and energy demands, which is also a key metabolic pathway that regulates NEB development during the perinatal period. Fibroblast Growth Factor 21 (FGF21) is a novel metabolic regulator involved in the control of fatty acid oxidation and lipid metabolism during a prolonged negative energy balance. Our study determined a correlation between serum FGF21 and β-hydroxybutyric acid (BHBA) levels in dairy cows with ketosis. We used sixty cows with low milk yield, abnormal glucose metabolism, and ketosis. Serum FGF21 and BHBA levels were measured using commercial kits. Serum FGF21 increased with increasing BHBA levels up to 1.6 mmol/L. At BHBA levels > 1.6 mmol/L, FGF21 decreased. Serum FGF21 levels were positively associated with BHBA levels, particularly in dairy cows with subclinical ketosis (r = 0.647, P < 0.01). At BHBA levels between 1.2 mmol/L and 1.6 mmol/L, FGF21 was more closely correlated with BHBA than with other metabolic parameters. At BHBA levels > 1.6 mmol/L, the association between FGF21 and BHBA was not significant. In conclusion, our results show that FGF21 was closely related with SK in cows. FGF21 may be a promising regulator in the prevention of subclinical ketosis.

Phosphoglucose isomerase gene expression as a prognostic biomarker of gastric cancer.

ObjectiveTumor heterogeneity renders identification of suitable biomarkers of gastric cancer (GC) challenging. Here, we aimed to identify prognostic genes of GC using computational analysis.MethodsWe first used microarray technology to profile gene expression of GC and paired nontumor tissues from 198 patients. Based on these profiles and patients’ clinical information, we next identified prognostic genes using novel computational approaches. Phosphoglucose isomerase, also known as glucose-6-phosphate isomerase (GPI), which ranked first among 27 candidate genes, was further investigated by a new analytical tool namely enviro-geno-pheno-state (E-GPS) analysis. Suitability of GPI as a prognostic marker, and its relationship with physiological processes such as metabolism, epithelial-mesenchymal transition (EMT), as well as drug sensitivity were evaluated using both our own and independent public datasets. ResultsWe found that higher expression of GPI in GC correlated with prolonged survival of patients. Particularly, a combination of CDH2 and GPI expression effectively stratified the outcomes of patients with TNM stage II/III. Down-regulation of GPI in tumor tissues correlated well with depressed glucose metabolism and fatty acid synthesis, as well as enhanced fatty acid oxidation and creatine metabolism, indicating that GPI represents a suitable marker for increased probability of EMT in GC cells. ConclusionsOur findings strongly suggest that GPI acts as a novel biomarker candidate for GC prognosis, allowing greatly enhanced clinical management of GC patients. The potential metabolic rewiring correlated with GPI also provides new insights into studying the relationship between cancer metabolism and patient survival.

Dietary methionine restriction reduces hepatic steatosis and oxidative stress in high-fat-fed mice by promoting H2S production.

Methionine is an essential amino acid that plays important roles in mammalian metabolism. Interestingly, previous studies have consistently shown that a methionine-restricted diet (MRD) reduces hepatic lipid levels, reactive oxygen species production, and oxidative stress damage. However, the mechanisms responsible for these beneficial effects are unknown. Therefore, our study was aimed at investigating the hepatic systemic metabolic responses to MRD in high-fat-diet (HFD) mice and to clarify the possible mechanisms of such responses. C57BL/6J mice were fed a control diet (0.86% methionine + 4% fat), HFD (0.86% methionine + 20% fat), or MRD (0.17% methionine + 20% fat) for 22 consecutive weeks, and euthanized at week 11 or week 22. Our results showed that HFD inhibited hepatic energy expenditure, induced steatosis and oxidative stress, and decreased hydrogen sulfide (H2S) production in the mouse liver. MRD reduced the body weight, liver fat percentage, and plasma and hepatic lipid profiles. Moreover, MRD decreased lipid synthesis, increased energy metabolism (e.g. lipid catabolism and fatty acid oxidation, glycolysis and tricarboxylic acid cycle metabolism, and amino acid catabolism), enhanced the activity of antioxidant enzymes, and reduced the levels of oxidative damage products and purine metabolism in the liver. Furthermore, MRD up-regulated the hepatic gene and protein expression of cystathionine-γ-lyase (CSE), elevated the hepatic CSE activity, and promoted hepatic H2S production. These findings suggest that MRD can ameliorate the hepatic metabolic disorders induced by HFD and especially reduce hepatic steatosis and oxidative stress likely through increasing hepatic H2S production.

Effects of caloric restriction on neuropathic pain, peripheral nerve degeneration and inflammation in normometabolic and autophagy defective prediabetic Ambra1 mice.

There is a growing interest on the role of autophagy in diabetes pathophysiology, where development of neuropathy is one of the most frequent comorbidities. We have previously demonstrated that neuropathic pain after nerve damage is exacerbated in autophagy-defective heterozygous Ambra1 mice. Here, we show the existence of a prediabetic state in Ambra1 mice, characterized by hyperglycemia, intolerance to glucose and insulin resistance. Thus, we further investigate the hypothesis that prediabetes may account for the exacerbation of allodynia and chronic pain and that counteracting the autophagy deficit may relieve the neuropathic condition. We took advantage from caloric restriction (CR) able to exert a double action: a powerful increase of autophagy and a control on the metabolic status. We found that CR ameliorates neuropathy throughout anti-inflammatory and metabolic mechanisms both in Ambra1 and in WT animals subjected to nerve injury. Moreover, we discovered that nerve lesion represents, per se, a metabolic stressor and CR reinstates glucose homeostasis, insulin resistance, incomplete fatty acid oxidation and energy metabolism. As autophagy inducer, CR promotes and anticipates Schwann cell autophagy via AMP-activated protein kinase (AMPK) that facilitates remyelination in peripheral nerve. In summary, we provide new evidence for the role of autophagy in glucose metabolism and identify in energy depletion by dietary restriction a therapeutic approach in the fight against neuropathic pain.

Chinese yellow cattle PPARA gene: Analyses of expression, polymorphism and trait association

Peroxisome proliferator-activated receptor alpha (PPARA) is a member of the nuclear receptor superfamily that regulates key proteins involved in fatty acid oxidation and extracellular lipid metabolism. Given the importance of PPARA in modulating energy metabolism, PPARA may be a suitable candidate gene for assessing economic traits in cattle. In the present study, the genetic diversity of the PPARA gene in Chinese cattle breeds and its effects on growth traits in the Nanyang and Jiaxian breeds were investigated. First, the transcript profiles for PPARA were determined in eight adult cattle tissue types. Next, polymorphisms were identified in the coding and predicted promoter regions of the bovine PPARA gene in 424 animals. Finally, an association study was carried out to evaluate the relationship between PPARA and the development of cattle. Based on quantitative real-time polymerase chain reaction, PPARA was mainly expressed in the kidney and liver. Nine single nucleotide polymorphisms (SNPs) were identified in Chinese domestic cattle, including one novel SNP. Haplotype frequencies and linkage disequilibrium were also investigated. Four SNPs (g.17148558A>T, g.117195348A>G, g.117228160T>C, and g.117233248A>G) showed significant associations with growth traits in NY and JX cattle, including body weight, average daily gain, and hipbone width. These results confirmed the importance of PPARA as a candidate gene for marker-assisted selection for growth traits in cattle.

Regulation by Dietary Carbohydrates of Intermediary Metabolism in Liver and Muscle of Two Isogenic Lines of Rainbow Trout.

Rainbow trout (Oncorhynchus mykiss) is recognized as a typical “glucose-intolerant” fish, and the limits of dietary carbohydrate utilization have been investigated for many years. In this study, the objective was to test the molecular effects of dietary carbohydrates on intermediary metabolism in two major metabolic tissues, liver and muscle. Another objective was also to study if the response to carbohydrate intake depended on the genetic background. We fed two isogenic lines of rainbow trout (named A22h and N38h) with high carbohydrate diet (carbohydrate, 22.9%) or low carbohydrate diet (carbohydrate, 3.6%) for 12 weeks. Carbohydrates were associated with higher feed utilization owned by the well-known protein-sparing effect, with better fish growth performance. However, atypical regulation of glycolysis and gluconeogenesis in liver and absence of hk and glut4 induction in muscle, were also observed. Regarding the effects of carbohydrates on other metabolism, we observed an increased, at a molecular level, of hepatic cholesterol biosynthesis, fatty acid oxidation and mitochondrial energy metabolism. Genetic variability (revealed by the differences between the two isogenic lines) was observed for some metabolic genes especially for those involved in the EPA and DHA biosynthetic capacity. Finally, our study demonstrates that dietary carbohydrate not only affect glucose metabolism but also strongly impact the lipid and energy metabolism in liver and muscle of trout.

Dicer in Macrophages Prevents Atherosclerosis by Promoting Mitochondrial Oxidative Metabolism.

Alternative macrophage activation, which relies on mitochondrial oxidative metabolism, plays a central role in the resolution of inflammation and prevents atherosclerosis. Moreover, macrophages handle large amounts of cholesterol and triglycerides derived from the engulfed modified lipoproteins during atherosclerosis. Although several microRNAs regulate macrophage polarization, the role of the microRNA-generating enzyme Dicer in macrophage activation during atherosclerosis is unknown. To evaluate the role of Dicer in atherosclerosis, Apoe-/- mice with or without macrophage-specific Dicer deletion were fed a high-fat diet for 12 weeks. Anti-argonaute 2 RNA immunoprecipitation chip and RNA deep sequencing combined with microRNA functional screening were performed in the Dicer wild-type and knockout bone marrow-derived macrophages to identify the individual microRNAs and the mRNA targets mediating the phenotypic effects of Dicer. The role of the identified individual microRNA and its target in atherosclerosis was determined by tail vein injection of the target site blockers in atherosclerotic Apoe-/- mice. We show that Dicer deletion in macrophages accelerated atherosclerosis in mice, along with enhanced inflammatory response and increased lipid accumulation in lesional macrophages. In vitro, alternative activation was limited whereas lipid-filled foam cell formation was exacerbated in Dicer-deficient macrophages as a result of impaired mitochondrial fatty acid oxidative metabolism. Rescue of microRNA (miR)-10a, let-7b, and miR-195a expression restored the oxidative metabolism in alternatively activated Dicer-deficient macrophages. Suppression of ligand-dependent nuclear receptor corepressor by miR-10a promoted fatty acid oxidation, which mediated the lipolytic and anti-inflammatory effect of Dicer. miR-10a expression was negatively correlated to the progression of atherosclerosis in humans. Blocking the interaction between ligand-dependent nuclear receptor corepressor and miR-10a by target site blockers aggravated atherosclerosis development in mice. Dicer plays an atheroprotective role by coordinately regulating the inflammatory response and lipid metabolism in macrophages through enhancing fatty acid-fueled mitochondrial respiration, suggesting that promoting Dicer/miR-10a-dependent metabolic reprogramming in macrophages has potential therapeutic implications to prevent atherosclerosis.

Bhlhe40 differentially regulates the function and number of peroxisomes and mitochondria in myogenic cells

PGC-1α is a key regulator of oxidative metabolism facilitating the expression of genes critical for the function and biogenesis of the two key oxidative organelles, mitochondria and peroxisomes, in skeletal muscle (SKM) and other organs. Our recent studies have found that the transcription factor Bhlhe40 negatively regulates PGC-1α gene expression and its coactivational activity, therefore, this factor should have profound influence on the biogenesis and metabolic activity of mitochondria and peroxisomes. Here we found that both the number and activity of peroxisomes were increased upon knockdown of Bhlhe40 expression but were repressed by its over-expression. Mitochondrial efficiency was significantly reduced by Bhlhe40 knockdown, resulting in the burst of ROS. Over-expression of a constitutively active PGC-1α-interactive domain (named as VBH135) of Bhlhe40 mimicked the effects of its knockdown on peroxisomes but simultaneously reduced ROS level. Furthermore, the efficiency, but not the number, of mitochondria was also increased by VBH135, suggesting differential regulation of peroxisomes and mitochondria by Bhlhe40. Unsaturated fatty acid oxidation, insulin response, and oxidative respiration were highly enhanced in Bhlhe40 knockdown or VBH135 over-expressed cells, suggesting the importance of Bhlhe40 in the regulation of unsaturated fatty acid and glucose oxidative metabolism. Expression profiling of genes important for either organelle also supports differential regulation of peroxisomes and mitochondria by Bhlhe40. These observations have established the important role of Bhlhe40 in SKM oxidative metabolism as the critical regulator of peroxisome and mitochondrion biogenesis and functions, and thus should provide a novel route for developing drugs targeting SKM metabolic diseases.

Forcing ATGL expression in hepatocarcinoma cells imposes glycolytic rewiring through PPAR-\u03b1/p300-mediated acetylation of p53

Metabolic reprogramming is a typical feature of cancer cells aimed at sustaining high-energetic demand and proliferation rate. Here, we report clear-cut evidence for decreased expression of the adipose triglyceride lipase (ATGL), the first and rate-limiting enzyme of triglyceride hydrolysis, in both human and mouse-induced hepatocellular carcinoma (HCC). We identified metabolic rewiring as major outcome of ATGL overexpression in HCC-derived cell lines. Indeed, ATGL slackened both glucose uptake/utilization and cell proliferation in parallel with increased oxidative metabolism of fatty acids and enhanced mitochondria capacity. We ascribed these ATGL—downstream events to the activity of the tumor-suppressor p53, whose protein levels—but not transcript—were upregulated upon ATGL overexpression. The role of p53 was further assessed by abrogation of the ATGL-mediated effects upon p53 silencing or in p53-null hepatocarcinoma Hep3B cells. Furthermore, we provided insights on the molecular mechanisms governed by ATGL in HCC cells, identifying a new PPAR-α/p300 axis responsible for p53 acetylation/accumulation. Finally, we highlighted that ATGL levels confer different susceptibility of HCC cells to common therapeutic drugs, with ATGL overexpressing cells being more resistant to glycolysis inhibitors (e.g., 2-deoxyglucose and 3-bromopyruvate), compared to genotoxic compounds. Collectively, our data provide evidence for a previously uncovered tumor-suppressor function of ATGL in HCC, with the outlined molecular mechanisms shedding light on new potential targets for anticancer therapy.

Plasma metabonomics investigation reveals involvement of fatty acid oxidation in hematotoxicity in Chinese benzene-exposed workers with low white blood cell count.

Benzene is an environmental and occupational contaminant. Health hazards associated with occupational benzene exposure is a major public health problem in China. In this study, we analyzed metabolite profiles among plasma samples collected from benzene-exposed workers with low white blood cell count (BLWs) and healthy controls using high-performance liquid chromatography-time-of-flight mass spectrometry. To screen potential benzene hematotoxicity biomarkers and metabolic pathways, principal component analysis was used to examine metabolite profile changes in plasma samples. The alterations in fatty acid oxidation (FAO) pathway were consistent with our previous findings in a mouse model; hence, two key genes were selected and verified in WBC samples. A total of nine identified metabolites were significantly changed in BLWs, which were involved in glutathione metabolism, porphyrin metabolism, lipid metabolism pathway, and FAO metabolism. Furthermore, compared with healthy controls, the mRNA expressions of carnitine acyltransferase (CRAT) and ACADVL were significantly increased in BLWs. Particularly, WBC counts was negatively correlated with the expression of AVADVL in BLWs. These aberrant metabolites could act as potential biomarkers for benzene hematotoxicity. In addition, fatty acid oxidation pathway may play a critical role in the development of hematotoxicity caused by benzene.

A new AMPK activator, GSK773, corrects fatty acid oxidation and differentiation defect in CPT2-deficient myotubes.

Carnitine palmitoyl transferase 2 (CPT2) deficiency is one of the most common inherited fatty acid oxidation (FAO) defects and represents a prototypical mitochondrial metabolic myopathy. Recent studies have suggested a pivotal role of adenosine monophosphate-activated protein kinase (AMPK) in skeletal muscle plasticity and mitochondrial homeostasis. Thus, we tested the potential of GSK773, a novel direct AMPK activator, to improve or correct FAO capacities in muscle cells from patients harboring various mutations. We used controls' and patients' myotubes and studied the parameters of FAO metabolism, of mitochondrial quantity and quality and of differentiation. We found that AMPK is constitutively activated in patients' myotubes, which exhibit both reduced FAO and impaired differentiation. GSK773 improves or corrects several metabolic hallmarks of CPT2 deficiency (deficient FAO flux and C16-acylcarnitine accumulation) by upregulating the expression of CPT2 protein. Beneficial effects of GSK773 are also likely due to stimulation of mitochondrial biogenesis and induction of mitochondrial fusion, by decreasing dynamin-related protein 1 and increasing mitofusin 2. GSK773 also induces a shift in myosin heavy chain isoforms toward the slow oxidative type and, therefore, fully corrects the differentiation process. We establish, through small interfering RNA knockdowns and pharmacological approaches, that these GSK773 effects are mediated through peroxisome proliferator-activated receptor gamma co-activator 1-alpha, reactive oxygen species and p38 mitogen-activated protein kinase, all key players of skeletal muscle plasticity. GSK773 recapitulates several important features of skeletal muscle adaptation to exercise. The results show that AMPK activation by GSK773 evokes the slow, oxidative myogenic program and triggers beneficial phenotypic adaptations in FAO-deficient myotubes. Thus, GSK773 might have therapeutic potential for correction of CPT2 deficiency.

Research Progress on Metabolic Regulatory Mechanisms of Hematopoietic Stem Cells -Review

Hematopoietic stem cells (HSC) are a class of stem cells with self-renewal and multipotent differentiation into a variety of blood cells and are most thoroughly studied, maturely applied in the clinic adult stem cell. Function of HSC is closely associated with metabolic regulation. The metabolic state mainly maintains HSC living in hypoxic bone marrow microenvironment depending on glycolysis for energy metabolism, and keeping low reactive oxygen species (ROS) level. Proteins like Hif-1, FoxO3, ATM, PTPMT1 protect HSC from ROS injury, maintaining HSC in hypoxic state. In addition, glucose metabolism-related enzymes, glutamine, fatty acid oxidation, purine and amino acid metabolism also play important roles in metabolic regulation of HSC. In this review the research progress on metabolism regnlation mechanisms of HSC is summurized, focusing on the mechanisms releted with oxydation metabolism regulation, carbohydrate metabolism level, purine metabolism and aminoacide metabolism.