Membrane Fatty Acid Transporters as Regulators of Lipid Metabolism: Implications for Metabolic Disease

The Cre8 amphilimus-eluting stent for the treatment of coronary artery disease: safety and efficacy profile

Introduction: Polymer-free drug-eluting stents are designed with stent surface modifications and drug-matrix formulations in order to release antiproliferative agents without the need of a polymer coating. Polymer-free technologies have the potential to overcome complications due to polymer persistence over time, such as local inflammatory reactions, delayed arterial healing, neoatherosclerosis, and subsequent ischemic adverse events.Areas covered: The Cre8 polymer-free amphilimus-eluting stent received CE mark in 2011 and was conceived with the aim of addressing the safety and efficacy limitations of early generation drug-eluting stents based on permanent polymer coatings. Besides the absence of polymer, the main features of the Cre8 stent include the abluminal reservoirs, the passive carbon film coating, and the antiproliferative agent formulation based on sirolimus mixed with free-fatty acid chain - namely amphilimus. This review will focus on the Cre8 development, technical characteristics, preclinical evidence, clinical efficacy and safety, and future perspectives.Expert opinion: The Cre8 stent has shown favorable angiographic and clinical outcomes at short and medium-term follow-up. This technology might provide a benefit in patients with diabetes. Further randomized evidence is required to provide an adequate clinical evaluation of this promising technology in patients with and without diabetes.

High-Fat Diet Increases Fat Oxidation and Promotes Skeletal Muscle Fatty Acid Transporter Expression in Exercise-Trained Mice

The aim of this study was to investigate the effect of a high-fat diet (HFD) on energy substrate utilization during long-term endurance exercise in mice. Male ICR mice (n = 32; 6 weeks old) were divided into two groups: low-fat diet (LFD, n = 16) and HFD (n = 16) and acclimatized to LFD or HFD feeding over 12 weeks. After 12 weeks, the two dietary groups were each divided into two groups with or without exercise (EX): LF-CON, LF-EX, HF-CON, and HF-EX groups. The exercise groups were trained to run on a treadmill for 12 weeks. At the end of the experimental protocol, energy metabolism in the whole body was measured at rest for 24 h and during exercise for 1 h using respiratory gas analysis. Furthermore, molecules involved in skeletal muscle fat metabolism were analyzed. Substrate utilization for energy metabolism in the whole body indicated that fat utilization was high in HFD intake. Notably, when HFD intake and exercise were combined, fat utilization was markedly increased during endurance exercise. In contrast, exercise showed no effect when combined with LFD intake. The gene expressions of Fat/Cd36, Fatp1, Fabp-pm, and Cpt1 were upregulated by HFD intake, with Fat/Cd36 and Cpt1 considerably elevated during long-term endurance exercise. In contrast, exercise showed no effect when combined with LFD intake. These results suggest that HFD intake effectively increased fat utilization as an energy substrate during long-term endurance exercise.

Developing substrate-based small molecule fluorescent probes for super-resolution fluorescent imaging of various membrane transporters

Super-resolution imaging technology has been a powerful tool for revealing fine biological structures and functions. Its high-quality imaging always needs highly accurate labeling. Here, by exploiting the high specificity and affinity of natural substrates to transporters, we developed one set of substrate-based small molecule fluorescent probes for labeling membrane transporters. A glucose-based probe (Glu-probe) and tyrosine-based probe (Tyr-probe) were synthesized as two examples. Confocal imaging showed that the Glu-probe could label glucose transporters on live cells by being stuck into the binding site. Compared with antibody-probe labeling, the labeling advantages of the Glu-probe were revealed. High specificity of the Glu-probe or Tyr-probe was examined by a colocalization experiment and glucose replacement or amino acid (AA) blocking. The synthetic probes were also tested on imaging HeLa cells to confirm their wide labeling application. Additionally, we found that membrane transporters were mostly in the clustered state on cellular membranes, changing their assembly pattern to regulate the transport effectiveness. These results suggest that the substrate-based probes can serve as valuable tools for investigating the spatial information of membrane transporters.

Pharmacological inhibition of TLR4 ameliorates muscle and liver ceramide content after disuse in previously physically active mice

Toll-like receptor 4 (TLR4) is a proposed mediator of ceramide accumulation, muscle atrophy, and insulin resistance in skeletal muscle. It is currently unknown whether pharmacological inhibition of TLR4, using the TLR4-specific inhibitor TAK-242 during muscle disuse, is able to prevent changes in intracellular ceramide species and consequently preserve muscle size and insulin sensitivity in physically active mice. To address this question, we subjected running wheel-conditioned C57BL/6 male mice (13 wk old; ∼10/group) to 7 days of hindlimb suspension (HS), 7 days of continued wheel running (WR), or daily injections of TAK-242 during HS (HS + TAK242) for 7 days. We measured hindlimb muscle morphology, intramuscular and liver ceramide content, HOMA-IR, mRNA proxies of ceramide turnover and lipid trafficking, and muscle fatty acid and glycerolipid content. As a result, soleus and liver ceramide abundance was greater (P < 0.05) in HS vs. WR but was reduced with TLR4 inhibition (HS + TAK-242 vs. HS). Muscle mass declined (P < 0.01) with HS (vs. WR), but TLR4 inhibition did not prevent this loss (soleus: P = 0.08; HS vs. HS + TAK-242). HOMA-IR was impaired (P < 0.01) in HS versus WR mice, but only fasting blood glucose was reduced with TLR4 inhibition (HS + TAK-242 vs HS, P < 0.05). Robust decreases in muscle Spt2 and Cd36 mRNA and muscle lipidomic trafficking may partially explain reductions in ceramides with TLR4 inhibition. In conclusion, pharmacological TLR4 inhibition in wheel-conditioned mice prevented ceramide accumulation during the early phase of hindlimb suspension (7 days) but had little effect on muscle size and insulin sensitivity.

Whole Genome Scan and Selection Signatures for Climate Adaption in Yanbian Cattle

Yanbian cattle is inhabitant of North of China, exhibiting many phenotypic features, such as long, dense body hair, and abundant intramuscular fat, designed to combat the extreme cold climate adaption. In the current study, we studied the cold tolerance of nine Yanbian cattle by whole genome resequencing and compared with African tropical cattle, N’Dama, as a control group. Yanbian cattle was aligned to the Bos taurus reference genome (ARS-UCD1.2) yielding an average of 10.8 fold coverage. The positive selective sweep analysis for the cold adaption in Yanbian cattle were analyzed using composite likelihood ratio (CLR) and nucleotide diversity (θπ), resulting in 292 overlapped genes. The strongest selective signal was found on BTA16 with potential mutation in CORT gene, a regulatory gene of primary hormone in the hypothalamic-pituitary-adrenal (HPA) axis, is reported to be associated with the cold stress, representedfour missense mutations (c.269C > T, p.Lys90Ile; c.251A > G, p.Glu84Gly; c.112C > T, p.Pro38Ser; c.86G > A, p.Pro29His). Meanwhile another gene on BTA6, showed significantly higher selective sweep signals for a cold adapted trait for hair follicle and length development, FGF5 (fibroblast growth factor 5) with a missense mutation (c.191C > T, p.Ser64Phe). Moreover, cold adapted Yanbian cattle was statistically compared with the hot adapted N’Dama cattle, a taurine cattle reported to show superior heat tolerance than zebu cattle, making them better adapted to the hot regions of Africa. XP-CLR, Fst, and θπ ratio were used to compare both breeds, yielding 487, 924, and 346 genes respectively. Among the 12 overlapped genes, (CD36) (c.638A > G, p.Lys 213Arg) involved in fat digestion and absorption plays an important role in membrane transport of long-chain fatty acid and its expression could increase in cold exposure. Henceforth, our study provides a novel genetic insights into the cold climate adaptation of Yanbian cattle and identified three candidate genes (CORT, FGF5, and CD36), which can add to an understanding of the cold climate adaptation of Yanbian cattle.

Augmenting Vacuolar H+-ATPase Function Prevents Cardiomyocytes from Lipid-Overload Induced Dysfunction

The diabetic heart is characterized by a shift in substrate utilization from glucose to lipids, which may ultimately lead to contractile dysfunction. This substrate shift is facilitated by increased translocation of lipid transporter CD36 (SR-B2) from endosomes to the sarcolemma resulting in increased lipid uptake. We previously showed that endosomal retention of CD36 is dependent on the proper functioning of vacuolar H⁺-ATPase (v-ATPase). Excess lipids trigger CD36 translocation through inhibition of v-ATPase function. Conversely, in yeast, glucose availability is known to enhance v-ATPase function, allowing us to hypothesize that glucose availability, via v-ATPase, may internalize CD36 and restore contractile function in lipid-overloaded cardiomyocytes. Increased glucose availability was achieved through (a) high glucose (25 mM) addition to the culture medium or (b) adenoviral overexpression of protein kinase-D1 (a kinase mediating GLUT4 translocation). In HL-1 cardiomyocytes, adult rat and human cardiomyocytes cultured under high-lipid conditions, each treatment stimulated v-ATPase re-assembly, endosomal acidification, endosomal CD36 retention and prevented myocellular lipid accumulation. Additionally, these treatments preserved insulin-stimulated GLUT4 translocation and glucose uptake as well as contractile force. The present findings reveal v-ATPase functions as a key regulator of cardiomyocyte substrate preference and as a novel potential treatment approach for the diabetic heart.

Suppressing fatty acid uptake has therapeutic effects in preclinical models of prostate cancer

Metabolism alterations are hallmarks of cancer, but the involvement of lipid metabolism in disease progression is unclear. We investigated the role of lipid metabolism in prostate cancer using tissue from patients with prostate cancer and patient-derived xenograft mouse models. We showed that fatty acid uptake was increased in human prostate cancer and that these fatty acids were directed toward biomass production. These changes were mediated, at least partly, by the fatty acid transporter CD36, which was associated with aggressive disease. Deleting Cd36 in the prostate of cancer-susceptible Pten^-/- mice reduced fatty acid uptake and the abundance of oncogenic signaling lipids and slowed cancer progression. Moreover, CD36 antibody therapy reduced cancer severity in patient-derived xenografts. We further demonstrated cross-talk between fatty acid uptake and de novo lipogenesis and found that dual targeting of these pathways more potently inhibited proliferation of human cancer-derived organoids compared to the single treatments. These findings identify a critical role for CD36-mediated fatty acid uptake in prostate cancer and suggest that targeting fatty acid uptake might be an effective strategy for treating prostate cancer.

Plasma CD36 and Incident Diabetes: A Case-Cohort Study in Danish Men and Women

BACKGROUND

Membrane CD36 is a fatty acid transporter implicated in the pathogenesis of metabolic disease. We aimed to evaluate the association between plasma CD36 levels and diabetes risk and to examine if the association was independent of adiposity among Danish population.

METHODS

We conducted a case-cohort study nested within the Danish Diet, Cancer and Health study among participants free of cardiovascular disease, diabetes and cancer and with blood samples and anthropometric measurements (height, weight, waist circumference, and body fat percentage) at baseline (1993 to 1997). CD36 levels were measured in 647 incident diabetes cases that occurred before December 2011 and a total of 3,515 case-cohort participants (236 cases overlap).

RESULTS

Higher plasma CD36 levels were associated with higher diabetes risk after adjusting for age, sex and other lifestyle factors. The hazard ratio (HR) comparing high versus low tertile of plasma CD36 levels was 1.36 (95% confidence interval [CI], 1.00 to 1.86). However, the association lost its significance after further adjustment for different adiposity indices such as body mass index (HR, 1.23; 95% CI, 0.87 to 1.73), waist circumference (HR, 1.21; 95% CI, 0.88 to 1.68) or body fat percentage (HR, 1.20; 95% CI, 0.86 to 1.66). Moreover, raised plasma CD36 levels were moderately associated with diabetes risk among lean participants, but the association was not present among overweight/obese individuals.

CONCLUSION

Higher plasma CD36 levels were associated with higher diabetes risk, but the association was not independent of adiposity. In this Danish population, the association of CD36 with diabetes risk could be either mediated or confounded by adiposity.

TGFβ2-induced formation of lipid droplets supports acidosis-driven EMT and the metastatic spreading of cancer cells

Acidosis, a common characteristic of the tumor microenvironment, is associated with alterations in metabolic preferences of cancer cells and progression of the disease. Here we identify the TGF-β2 isoform at the interface between these observations. We document that acidic pH promotes autocrine TGF-β2 signaling, which in turn favors the formation of lipid droplets (LD) that represent energy stores readily available to support anoikis resistance and cancer cell invasiveness. We find that, in cancer cells of various origins, acidosis-induced TGF-β2 activation promotes both partial epithelial-to-mesenchymal transition (EMT) and fatty acid metabolism, the latter supporting Smad2 acetylation. We show that upon TGF-β2 stimulation, PKC-zeta-mediated translocation of CD36 facilitates the uptake of fatty acids that are either stored as triglycerides in LD through DGAT1 or oxidized to generate ATP to fulfill immediate cellular needs. We also address how, by preventing fatty acid mobilization from LD, distant metastatic spreading may be inhibited.

The tumour microenvironment is known to have an acidic pH but how this influences cancer cell phenotype is unclear. Here, the authors show that tumour cells upregulate TGF-β2 under acidosis, which leads to the increased formation of lipid droplets allowing for invasiveness and metastases.

Sensitive Detection of Protein Binding to the Plasma Membrane with Dual-Color Z-Scan Fluorescence

Delicate and transitory protein engagement at the plasma membrane (PM) is crucial to a broad range of cellular functions, including cell motility, signal transduction, and virus replication. Here, we describe a dual-color (DC) extension of the fluorescence z-scan technique, which has proven successful for quantification of peripheral membrane protein binding to the PM in living cells. We demonstrate that the coexpression of a second, distinctly colored fluorescent protein provides a soluble reference species that delineates the extent of the cell cytoplasm and lowers the detection threshold of z-scan PM-binding measurements by an order of magnitude. DC z-scan generates an intensity profile for each detection channel that contains information on the axial distribution of the peripheral membrane and reference protein. Fit models for DC z-scan are developed and verified using simple model systems. Next, we apply the quantitative DC z-scan technique to investigate the binding of two peripheral membrane protein systems for which previous z-scan studies failed to detect binding: human immunodeficiency virus type 1 (HIV-1) matrix (MA) protein and lipidation-deficient mutants of the fibroblast growth factor receptor substrate 2α. Our findings show that these mutations severely disrupt PM association of fibroblast growth factor receptor substrate 2α but do not eliminate it. We further detected binding of HIV-1 MA to the PM using DC z-scan. Interestingly, our data indicate that HIV-1 MA binds cooperatively to the PM with a dissociation coefficient of K_d ∼16 μM and Hill coefficient of n ∼2.

Treatment of human skeletal muscle cells with inhibitors of diacylglycerol acyltransferases 1 and 2 to explore isozyme-specific roles on lipid metabolism

Diacylglycerol acyltransferases (DGAT) 1 and 2 catalyse the final step in triacylglycerol (TAG) synthesis, the esterification of fatty acyl-CoA to diacylglycerol. Despite catalysing the same reaction and being present in the same cell types, they exhibit different functions on lipid metabolism in various tissues. Yet, their roles in skeletal muscle remain poorly defined. In this study, we investigated how selective inhibitors of DGAT1 and DGAT2 affected lipid metabolism in human primary skeletal muscle cells. The results showed that DGAT1 was dominant in human skeletal muscle cells utilizing fatty acids (FAs) derived from various sources, both exogenously supplied FA, de novo synthesised FA, or FA derived from lipolysis, to generate TAG, as well as being involved in de novo synthesis of TAG. On the other hand, DGAT2 seemed to be specialised for de novo synthesis of TAG from glycerol-3-posphate only. Interestingly, DGAT activities were also important for regulating FA oxidation, indicating a key role in balancing FAs between storage in TAG and efficient utilization through oxidation. Finally, we observed that inhibition of DGAT enzymes could potentially alter glucose-FA interactions in skeletal muscle. In summary, treatment with DGAT1 or DGAT2 specific inhibitors resulted in different responses on lipid metabolism in human myotubes, indicating that the two enzymes play distinct roles in TAG metabolism in skeletal muscle.

CD36 (SR-B2) as a Target to Treat Lipid Overload-Induced Cardiac Dysfunction

The heart faces the challenge of adjusting the rate of fatty acid uptake to match myocardial demand for energy provision at any given moment, avoiding both too low uptake rates, which could elicit an energy deficit, and too high uptake rates, which pose the risk of excess lipid accumulation and lipotoxicity. The transmembrane glycoprotein cluster of differentiation 36 (CD36), a scavenger receptor (B2), serves many functions in lipid metabolism and signaling. In the heart, CD36 is the main sarcolemmal lipid transporter involved in the rate-limiting kinetic step in cardiac lipid utilization. The cellular fatty acid uptake rate is determined by the presence of CD36 at the cell surface, which is regulated by subcellular vesicular recycling from endosomes to the sarcolemma. CD36 has been implicated in dysregulated fatty acid and lipid metabolism in pathophysiological conditions, particularly high-fat diet-induced insulin resistance and diabetic cardiomyopathy. Thus, in conditions of chronic lipid overload, high levels of CD36 are moved to the sarcolemma, setting the heart on a route towards increased lipid uptake, excessive lipid accumulation, insulin resistance, and eventually contractile dysfunction. Insight into the subcellular trafficking machinery of CD36 will provide novel targets to treat the lipid-overloaded heart. A screen for CD36-dedicated trafficking proteins found that vacuolar-type H⁺-ATPase and specific vesicle-associated membrane proteins, among others, were uniquely involved in CD36 recycling. Preliminary data suggest that these proteins may offer clues on how to manipulate myocardial lipid uptake, and thus could be promising targets for metabolic intervention therapy to treat the failing heart.

High-Intensity Interval Training Restores Glycolipid Metabolism and Mitochondrial Function in Skeletal Muscle of Mice With Type 2 Diabetes

High-intensity interval training has been reported to lower fasting blood glucose and improve insulin resistance of type 2 diabetes without clear underlying mechanisms. The purpose of this study was to investigate the effect of high-intensity interval training on the glycolipid metabolism and mitochondrial dynamics in skeletal muscle of high-fat diet (HFD) and one-time 100 mg/kg streptozocin intraperitoneal injection-induced type 2 diabetes mellitus (T2DM) mice. Our results confirmed that high-intensity interval training reduced the body weight, fat mass, fasting blood glucose, and serum insulin of the T2DM mice. High-intensity interval training also improved glucose tolerance and insulin tolerance of the T2DM mice. Moreover, we found that high-intensity interval training also decreased lipid accumulation and increased glycogen synthesis in skeletal muscle of the T2DM mice. Ultrastructural analysis of the mitochondria showed that mitochondrial morphology and quantity were improved after 8 weeks of high-intensity interval training. Western blot analysis showed that the expression of mitochondrial biosynthesis related proteins and mitochondrial dynamics related proteins in high-intensity interval trained mice in skeletal muscle were enhanced. Taken together, these data suggest high-intensity interval training improved fasting blood glucose and glucose homeostasis possibly by ameliorating glycolipid metabolism and mitochondrial dynamics in skeletal muscle of the T2DM mice.

Lipid oversupply induces CD36 sarcolemmal translocation via dual modulation of PKCζ and TBC1D1: an early event prior to insulin resistance

Lipid oversupply may induce CD36 sarcolemmal translocation to facilitate fatty acid transport, which in turn causes dyslipidemia and type 2 diabetes. However, the underlying mechanisms of CD36 redistribution are still yet to be unraveled.

Methods: High fat diet fed mice and palmitate/oleic acid-treated L6 cells were used to investigate the initial events of subcellular CD36 recycling prior to insulin resistance. The regulation of CD36 sarcolemmal translocation by lipid oversupply was assessed by insulin tolerance test (ITT), oral glucose tolerance test (OGTT), glucose/fatty acid uptake assay, surface CD36 and GLUT4 detection, and ELISA assays. To elucidate the underlying mechanisms, specific gene knockout, gene overexpression and/or gene inhibition were employed, followed by Western blot, co-immunoprecipitation, immunostaining, and kinase activity assay.

Results: Upon lipid/fatty acid overload, PKCζ activity and TBC1D1 phosphorylation were enhanced along with increased sarcolemmal CD36. The inhibition of PKCζ or TBC1D1 was shown to block fatty acid-induced CD36 translocation and was synergistic in impairing CD36 redistribution. Mechanically, we revealed that AMPK was located upstream of PKCζ to control its activity whereas Rac1 facilitated PKCζ translocation to the dorsal surface of the cell to cause actin remodeling. Furthermore, AMPK phosphorylated TBC1D1 to release retained cytosolic CD36. The activated PKCζ and phosphorylated TBC1D1 resulted in a positive feedback regulation of CD36 sarcolemmal translocation.

Conclusion: Collectively, our study demonstrated exclusively that lipid oversupply induced CD36 sarcolemmal translocation via dual modulation of PKCζ and TBC1D1, which was as an early event prior to insulin resistance. The acquired data may provide potential therapy targets to prevent lipid oversupply-induced insulin resistance.

Coordinated Modulation of Energy Metabolism and Inflammation by Branched-Chain Amino Acids and Fatty Acids

As important metabolic substrates, branched-chain amino acids (BCAAs) and fatty acids (FAs) participate in many significant physiological processes, such as mitochondrial biogenesis, energy metabolism, and inflammation, along with intermediate metabolites generated in their catabolism. The increased levels of BCAAs and fatty acids can lead to mitochondrial dysfunction by altering mitochondrial biogenesis and adenosine triphosphate (ATP) production and interfering with glycolysis, fatty acid oxidation, the tricarboxylic acid cycle (TCA) cycle, and oxidative phosphorylation. BCAAs can directly activate the mammalian target of rapamycin (mTOR) signaling pathway to induce insulin resistance, or function together with fatty acids. In addition, elevated levels of BCAAs and fatty acids can activate the canonical nuclear factor-κB (NF-κB) signaling pathway and inflammasome and regulate mitochondrial dysfunction and metabolic disorders through upregulated inflammatory signals. This review provides a comprehensive summary of the mechanisms through which BCAAs and fatty acids modulate energy metabolism, insulin sensitivity, and inflammation synergistically.

Dual Effects of Lipid Metabolism on Osteoblast Function

The skeleton is a dynamic and metabolically active organ with the capacity to influence whole body metabolism. This newly recognized function has propagated interest in the connection between bone health and metabolic dysfunction. Osteoblasts, the specialized mesenchymal cells responsible for the production of bone matrix and mineralization, rely on multiple fuel sources. The utilization of glucose by osteoblasts has long been a focus of research, however, lipids and their derivatives, are increasingly recognized as a vital energy source. Osteoblasts possess the necessary receptors and catabolic enzymes for internalization and utilization of circulating lipids. Disruption of these processes can impair osteoblast function, resulting in skeletal deficits while simultaneously altering whole body lipid homeostasis. This article provides an overview of the metabolism of postprandial and stored lipids and the osteoblast's ability to acquire and utilize these molecules. We focus on the requirement for fatty acid oxidation and the pathways regulating this function as well as the negative impact of dyslipidemia on the osteoblast and skeletal health. These findings provide key insights into the nuances of lipid metabolism in influencing skeletal homeostasis which are critical to appreciate the extent of the osteoblast's role in metabolic homeostasis.

Shaping of Innate Immune Response by Fatty Acid Metabolite Palmitate

Innate immune cells monitor invading pathogens and pose the first-line inflammatory response to coordinate with adaptive immunity for infection removal. Innate immunity also plays pivotal roles in injury-induced tissue remodeling and the maintenance of tissue homeostasis in physiological and pathological conditions. Lipid metabolites are emerging as the key players in the regulation of innate immune responses, and recent work has highlighted the importance of the lipid metabolite palmitate as an essential component in this regulation. Palmitate modulates innate immunity not only by regulating the activation of pattern recognition receptors in local innate immune cells, but also via coordinating immunological activity in inflammatory tissues. Moreover, protein palmitoylation controls various cellular physiological processes. Herein, we review the updated evidence that palmitate catabolism contributes to innate immune cell-mediated inflammatory processes that result in immunometabolic disorders.

Probing the hepatotoxicity mechanisms of novel chlorinated polyfluoroalkyl sulfonates to zebrafish larvae: Implication of structural specificity

Hepatotoxicity in zebrafish (Danio rerio) larvae elicited by legacy perfluorooctane sulfonate (PFOS) and its three novel chlorinated alternatives, including chlorinated polyfluorooctane sulfonate (Cl-PFOS) and chlorinated polyfluoroalkyl ether sulfonates (6:2 and 8:2 Cl-PFESA analogs), was evaluated in this study. Upon 7-day separate exposure to the four target compounds at 1 µmol/L, significant hepatic steatosis in exposed larvae was evidenced by pathological micro/macro vacuolation, which was presumably attributed to the excess accumulation of lipid, especially the overloaded triglyceride (TG) level. Disruption on gene transcription was subjected to a structure-dependent manner. In general, PFOS, Cl-PFOS and 6:2 Cl-PFESA of the identical carbon chain length (i.e. C8), despite with different substituents, displayed a similar activation mode and comparable disruptive potency on lipid metabolism responsive genes, which particularly promoted fatty acid synthesis (acetyl-CoA carboxylase, acacb) and β-oxidation (cytochrome P450 enzymes-1A, cyp1a; peroxisomal acyl-CoA oxidase 1, acox1; and acyl-CoA dehy-drogenase, acadm). However, 8:2 Cl-PFESA with a prolonged carbon chain length (i.e. C10), preferentially disturbed fatty acid exportation (apolipoprotein-B100, apob) and triggered a different modulation pattern on fatty acid β-oxidation against the other three compounds. Molecular docking analysis indicated that 8:2 Cl-PFESA exhibited considerably higher peroxisome proliferator-activated receptors (PPARs) antagonism than others, corresponding to its unique suppression effect on fatty acid β-oxidation responsive genes. To our knowledge, this is the first in vivo study reporting hepatotoxicity of Cl-PFOS and Cl-PFESAs to aquatic organisms. Although characterized with different toxic mode-of-action, these novel alternatives can elicit hepatic steatosis as strong as PFOS, stressing the biological risks in view of their global contamination.

Lipid accumulation and mitochondrial abnormalities are associated with fiber atrophy in the skeletal muscle of rats with collagen-induced arthritis

Rheumatoid arthritis (RA) has a negative impact on muscle mass, and reduces patient's mobility and autonomy. Furthermore, RA is associated with metabolic comorbidities, notably in lipid homeostasis by unknown mechanisms. To understand the links between the loss in muscle mass and the metabolic abnormalities, arthritis was induced in male Sprague Dawley rats (n = 11) using the collagen-induced arthritis model. Rats immunized with bovine type II collagen were compared to a control group of animals (n = 11) injected with acetic acid and complete Freund's adjuvant. The clinical severity of the ensuing arthritis was evaluated weekly by a semi-quantitative score. Skeletal muscles from the hind limb were used for the histological analysis and exploration of mitochondrial activity, lipid accumulation, metabolism and regenerative capacities. A significant atrophy in tibialis anterior muscle fibers was observed in the arthritic rats despite a non-significant decrease in the weight of the muscles. Despite moderate inflammation, accumulation of triglycerides (P < 0.05), reduced mitochondrial DNA copy number (P < 0.05) and non-significant dysfunction in mitochondrial cytochrome c oxidase activity were found in the gastrocnemius muscle. Concomitantly, our results suggested an activation of the muscle specific E3 ubiquitin ligases MuRF-1 and MAFbx. Finally, the adipose tissue from the arthritic rats exhibited decreased PPARγ mRNA suggesting reduced adipogenic capacities. In conclusion, the reduced adipose tissue adipogenic capacity and skeletal muscle mitochondrial capacity are probably involved in the activation of protein catabolism, inhibition of myogenesis, accumulation of lipids and fiber atrophy in the skeletal muscle during RA.

Macrophage fatty acid metabolism and atherosclerosis: The rise of PUFAs

Among the pathways involved in the regulation of macrophage functions, the metabolism of unsaturated fatty acids is central. Indeed, unsaturated fatty acids act as precursors of bioactive molecules such as prostaglandins, leukotrienes, resolvins and related compounds. As components of phospholipids, they have a pivotal role in cell biology by regulating membrane fluidity and membrane-associated cellular processes. Finally, polyunsaturated fatty acids (PUFAs) are also endowed with ligand properties for numerous membrane or nuclear receptors. Although myeloid cells are dependent on the metabolic context for the uptake of essential FAs, recent studies showed that these cells autonomously handle the synthesis of n-3 and n-6 long chain PUFAs such as arachidonic acid and eicosapentaenoic acid. Moreover, targeting PUFA metabolism in macrophages influences pathological processes, including atherosclerosis, by modulating macrophage functions. Omics evidence also supports a role for macrophage PUFA metabolism in the development of cardiometabolic diseases in humans. Currently, there is a renewed interest in the role of n-3/n-6 PUFAs and their oxygenated derivatives in the onset of atherosclerosis and plaque rupture. Purified n-3 FA supplementation appears as a potential strategy in the treatment and prevention of cardiovascular diseases. In this context, the ability of immune cells to handle and to synthesize very long chain PUFA must absolutely be integrated and better understood.

Unraveling FATP1, regulated by ER-β, as a targeted breast cancer innovative therapy

The biochemical demands associated with tumor proliferation prompt neoplastic cells to augment the import of nutrients to sustain their survival and fuel cell growth, with a consequent metabolic remodeling. Fatty acids (FA) are crucial in this process, since they have a dual role as energetic coins and building blocks. Recently, our team has shown that FATP1 has a pivotal role in FA transfer between breast cancer cells (BCCs) and non-cancerous cells in the microenvironment. We aimed to investigate the role of FATP1 in BCCs and also to explore if FATP1 inhibition is a promising therapeutic strategy. In patients’ data, we showed a higher expression of FATP1/SLC27A1 in TNBC, which correlated with a significant decreased overall survival (OS). In vitro, we verified that FA and estradiol stimulated FATP1/SLC27A1 expression in BCCs. Additionally, experiments with estradiol and PHTPP (ER-β antagonist) showed that estrogen receptor-β (ER-β) regulates FATP1/SLC27A1 expression, the uptake of FA and cell viability, in four BCC lines. Furthermore, the inhibition of FATP1 with arylpiperazine 5k (DS22420314) interfered with the uptake of FA and cell viability. Our study, unraveled FATP1 as a putative therapeutic target in breast cancer (BC).

Neointimal hyperplasia: are fatty acid transport proteins a new therapeutic target?

PURPOSE OF REVIEW

High-fat diets contribute to hyperlipidemia and dysregulated metabolism underlying insulin resistant states and cardiovascular diseases. Neointimal hyperplasia is a significant resulting morbidity. Increased fatty acid (FA) levels lead to dysfunctional endothelium, defined as activated, proinflammatory and prothrombotic. The purpose of this review is to assess the recent literature on the emerging concept that uptake of FA into many tissues is regulated at the endothelial level, and this in turn contributes to endothelial dysfunction, an initiating factor in insulin resistant states, atherosclerosis and neointimal hyperplasia.

RECENT FINDINGS

Studies support the role of endothelial FA uptake proteins as an additional level of regulation in tissue FA uptake. These proteins include CD36, FA transport proteins, FA-binding proteins and caveolin-1. In many cases, inappropriate expression of these proteins can result in a change in FA and glucose uptake, storage and utilization. Accumulation of plasma FA is one mechanism by which alterations in expression of FA uptake proteins can lead to endothelial dysfunction; changes in tissue substrate metabolism leading to inflammation are also implicated.

SUMMARY

Identification of the critical players and regulators can lead to therapeutic targeting to reduce endothelial dysfunction and sequela such as insulin resistance and neointimal hyperplasia.

The expanded role of fatty acid metabolism in cancer: new aspects and targets

Cancer cells undergo metabolic reprogramming to support cell proliferation, growth, and dissemination. Alterations in lipid metabolism, and specifically the uptake and synthesis of fatty acids (FAs), comprise one well-documented aspect of this reprogramming. Recent studies have revealed an expanded range of roles played by FA in promoting the aggressiveness of cancer while simultaneously identifying new potential targets for cancer therapy. This article provides a brief review of these advances in our understanding of FA metabolism in cancer, highlighting both recent discoveries and the inherent challenges caused by the metabolic plasticity of cancer cells in targeting lipid metabolism for cancer therapy.

Mitochondria as a target of organophosphate and carbamate pesticides: Revisiting common mechanisms of action with new approach methodologies

Mitochondrial toxicity has been proposed as a potential cause of developmental defects in humans. We evaluated 51 organophosphate and carbamate pesticides using the U.S. EPA ToxCast and Tox21 databases. Only a small number of them bind directly to cholinesterases in the parent form. The hydrophobicity of organophosphate pesticides is correlated significantly to TSPO binding affinity, mitochondrial membrane potential reduction in HepG2 cells, and developmental toxicity in Caenorhabditis elegans and Danio rerio (p < 0.05). Structural analysis suggests that in some cases the Krebs cycle is a potential target of organophosphate and carbamate exposure at early life stages. The results support the hypothesis that mitochondrial effects of some organophosphate pesticides-particularly those that require enzymatic activation to the oxon form-may augment the documented effects of disruption of acetylcholine signaling. This study provides a proof of concept for applying new approach methodologies to interrogate mechanisms of action for cumulative risk assessment.

Developmental Accretion of Docosahexaenoic Acid Is Independent of Fatty Acid Transporter Expression in Brain and Lung Tissues of C57BL/6 and Fat1 Mice

BACKGROUND

Developmental expression of fatty acid transporters and their role in polyunsaturated fatty acid concentrations in the postnatal period have not been evaluated.

OBJECTIVE

We hypothesized that transporter expression is developmentally regulated, tissue-specific, and that expression can modulate fatty acid accretion independently of diet.

METHODS

Brain and lung transporter expression were quantified in C57BL/6 wild-type (WT) and Fat1 mice. Pups were dam-fed until day 21. Dams were fed AIN-76A 10% corn oil to represent a typical North American/European diet. After weaning, mice were fed the same diet as dams. Gene expression of Fatp1, Fatp4, Fabp5, and Fat/cd36 was quantified by quantitative reverse transcriptase-polymerase chain reaction. Fatty acid concentrations were measured by GC-MS.

RESULTS

Brain docosahexaenoic acid (DHA) concentrations increased from day 3 to day 28 in both genotypes, with higher concentrations at days 3 and 14 in Fat1 than in WT mice [median (IQR)]: 10.7 (10.6-11.2) mol% compared with 6.6 (6.4-7.2) mol% and 12.5 (12.4-12.9) mol% compared with 8.9 (8.7-9.1) mol%, respectively; P < 0.05). During DHA accrual, transporter expression decreased. Fold changes in brain Fatp4, Fabp5, and Fat/cd36 were inversely correlated with fold changes in brain DHA concentrations in Fat1 relative to WT mice (ρ = -0.85, -0.75, and -0.78, respectively; P ≤ 0.001). Lung DHA concentrations were unchanged across the 3 time points for both genotypes. Despite unchanging DHA concentrations, there was increased expression of Fatp1 at days 14 and 28 (5-fold), Fatp4 at day 14 (2.3-fold), and Fabp5 at day 14 (3.8-fold) relative to day 3 in Fat1 mice. In WT mice, Fatp1 increased almost 5-fold at day 28 relative to day 3. There was no correlation between lung transporters and DHA concentrations in Fat1 relative to WT mice.

CONCLUSIONS

Development of fatty acid transporter expression in C57BL/6 WT and Fat1 mice is genotype and tissue specific. Further, postnatal accretion of brain DHA appears independent of transporter status, with tissue concentrations representing dietary contributions.

Metabolic Coordination of Physiological and Pathological Cardiac Remodeling

Metabolic pathways integrate to support tissue homeostasis and to prompt changes in cell phenotype. In particular, the heart consumes relatively large amounts of substrate not only to regenerate ATP for contraction but also to sustain biosynthetic reactions for replacement of cellular building blocks. Metabolic pathways also control intracellular redox state, and metabolic intermediates and end products provide signals that prompt changes in enzymatic activity and gene expression. Mounting evidence suggests that the changes in cardiac metabolism that occur during development, exercise, and pregnancy as well as with pathological stress (eg, myocardial infarction, pressure overload) are causative in cardiac remodeling. Metabolism-mediated changes in gene expression, metabolite signaling, and the channeling of glucose-derived carbon toward anabolic pathways seem critical for physiological growth of the heart, and metabolic inefficiency and loss of coordinated anabolic activity are emerging as proximal causes of pathological remodeling. This review integrates knowledge of different forms of cardiac remodeling to develop general models of how relationships between catabolic and anabolic glucose metabolism may fortify cardiac health or promote (mal)adaptive myocardial remodeling. Adoption of conceptual frameworks based in relational biology may enable further understanding of how metabolism regulates cardiac structure and function.

A microfluidic patterned model of non-alcoholic fatty liver disease: applications to disease progression and zonation

Non-alcoholic fatty liver disease (NAFLD) and its progressive form non-alcoholic steatohepatitis (NASH) affect 25% of the world population. NAFLD is predicted to soon become the main cause of liver morbidity and transplantation. The disease is characterized by a progressive increase of lipid accumulation in hepatocytes, which eventually induce fibrosis and inflammation, and can ultimately cause cirrhosis and hepatic carcinoma. Here, we created a patterned model of NAFLD on a chip using free fatty acid gradients to recapitulate a spectrum of disease conditions in a single continuous liver tissue. We established the NAFLD progression via quantification of intracellular lipid accumulation and transcriptional levels of fatty acid transporters and NAFLD pathogenesis markers. We then used this platform to create oxygen driven steatosis zonation mimicking the sinusoidal lipid distribution on a single continuous tissue and showed that this fat zonation disappears under progressed steatosis, in agreement with in vivo observations and recent computational studies. While we focus on free fatty acids and oxygen as the drivers of NAFLD, the microfluidic platform here is extensible to simultaneous use of other drivers.

Peroxisomal gene and protein expression increase in response to a high-lipid challenge in human skeletal muscle

Peroxisomes are essential for lipid metabolism and disruption of liver peroxisomal function results in neonatal death. Little is known about how peroxisomal content and activity respond to changes in the lipid environment in human skeletal muscle (HSkM).

AIMS

We hypothesized and tested that increased peroxisomal gene/protein expression and functionality occur in HSkM as an adaptive response to lipid oversupply.

MATERIALS AND METHODS

HSkM biopsies, derived from a total of sixty-two subjects, were collected for 1) examining correlations between peroxisomal proteins and intramyocellular lipid content (IMLC) as well as between peroxisomal functionality and IMLC, 2) assessing peroxisomal gene expression in response to acute- or 7-day high fat meal (HFM), and in human tissue derived primary myotubes for 3) treating with high fatty acids to induce peroxisomal adaptions. IMLC were measured by both biochemical analyses and fluorescent staining. Peroxisomal membrane protein PMP70 and biogenesis gene (PEX) expression were assessed using western blotting and realtime qRT-PCR respectively. 1-14C radiolabeled lignocerate and palmitate oxidation assays were performed for peroxisomal and mitochondrial functionality respectively.

RESULTS

1) Under fasting conditions, HSkM tissue demonstrated a significant correlation (P ≪ 0.05) between IMCL and the peroxisomal biogenesis factor 19 (PEX19) protein as well as between lipid content and palmitate and lignocerate complete oxidation. 2) Similarly, post-HFM, additional PEX genes (Pex19, PEX11A, and PEX5) were significantly (P ≪ 0.05) upregulated. 3) Increments in PMP70, carnitine octanoyl transferase (CrOT), PGC-1α, and ERRα mRNA were observed post-fatty acid incubation in HSkM cells. PMP70 protein was significantly (P ≪ 0.05) elevated 48-h post lipid treatment.

CONCLUSIONS

These results are the first to associate IMLC with peroxisomal gene/protein expression and function in HSkM suggesting an adaptive role for peroxisomes in lipid metabolism in this tissue.

Role of angiotensin type 2 receptor in improving lipid metabolism and preventing adiposity

Recent studies on mice with null mutation of the angiotensin type 2 receptor (AT₂R) gene have implicated the involvement of AT₂R in regulating adipocyte size and obesity, a major risk factor for metabolic syndrome. However, the outcome from these studies remains inconclusive. Therefore, current study was designed to test whether pharmacological activation of AT₂R regulates adiposity and lipid metabolism. Male mice (5-weeks old) were pre-treated with vehicle or AT₂R agonist (C21, 0.3 mg/kg, i.p., daily, for 4 days) and fed normal diet (ND). Then these animals were subdivided into ND and high-fat diet (HFD) regimen and concomitantly treated with vehicle or C21 through day 14. Vehicle-treated HFD-fed mice demonstrated an increase in epididymal white adipose tissue (eWAT) weight and adipocyte size, which were associated with increased eWAT expression of the lipogenic regulators, fatty acid binding protein and fatty acid synthase, decreased expression of adipose triglyceride lipase and increased expression of hormone-sensitive lipase. Interestingly, C21 pre-treatment altered HFD-induced changes in lipogenic and lipolytic regulators. C21 pre-treatment prevented decrease in expression of uncoupler protein-1 in brown adipose in HFD-fed mice, which was associated with increased core temperature. In addition, C21 pre-treatment ameliorated plasma-free fatty acids, triglycerides, insulin and tumor necrosis factor-α in HFD-fed mice. Ex-vivo study in isolated primary epididymal adipocytes revealed that C21 inhibits long chain fatty acid transporter, via a nitric oxide synthase/guanylate cyclase/protein kinase G-dependent pathway. Collectively, we propose pharmacological activation of AT₂R regulates fatty acid metabolism and thermogenesis and prevents HFD-induced adiposity in mice.

Elevated CD36 expression correlates with increased visceral adipose tissue and predicts poor prognosis in ccRCC patients

Objective: Growing evidence has proved obesity one of the confirmed important etiologic indicators for renal cell carcinoma (RCC). CD36 is underpinned to be involved in adipose absorption, but its role in clear cell renal cell carcinoma (ccRCC) remains unclear. This study aimed to investigate the mRNA expression of CD36 in anthropometric measures of adipose tissue and defining its value in predicting prognosis in ccRCC patients. Methods: Real-Time qPCR gene expression analysis was detected from 367 paired ccRCC and adjacent normal tissues. Distributions of categorical clinical-pathological data together with levels of CD36 expression were compared with χ²-test in a contingency table. Subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) were measured by magnetic resonance imaging (MRI) and identified at the level of the umbilicus. Pearson's correlation coefficient was utilized to quantify relations between body mass index (BMI), VAT%, SAT and CD36 expression respectively. Partial likelihood test from univariate and multivariate Cox regression analysis were developed to address the influence of independent factors on progression-free survival (PFS) and overall survival (OS). The Kaplan-Meier method and log-rank test were performed to assess the survival benefits between discrete levels. Results: In the current study, CD36 mRNA was demonstrated highly expressed in ccRCC compared with normal tissues. In addition, CD36 mRNA expression was significantly increased in patients with advanced TNM stage (p=0.003, p<0.001, p<0.001), and high VAT% (p=0.004). Pearson's correlation coefficient indicated that CD36 amplification positively correlated with BMI (r=0.117, p=0.025), VAT% (r=0.465, p<0.001), while negatively associated with SAT (r=-0.296, p=0.002). Median PFS was 60 months and OS was 99 months. Meanwhile, ccRCC patients with elevated CD36 expression held shorter PFS and OS, with hazard ratios [HR; 95% confidence interval (CI)] of 4.873 (3.300-7.196, p<0.001) and 4.610 (2.956-7.189, p<0.001). In 104 cases with available MRI scans, VAT was significantly correlated with poor PFS and OS, with HR of 2.556 (1.036-6.310, p<0.042) and 3.291 (1.034-10.477, p<0.044). A total of 100 significant genes were obtained from GSEA, and CD36 was found involved in the most significant pathways including fatty acid metabolism, UV response, angiogenesis and transforming growth factor beta (TGF-β) signaling pathways. Conclusion: In conclusion, our study first reveal that elevated CD36 mRNA expression is positively correlated to distribution of abdominal adipose, particularly VAT%, which, in addition, notably predicts poor prognosis in ccRCC patients.

Fatty acid-induced CD36 expression via O-GlcNAcylation drives gastric cancer metastasis

Metastasis is the primary cause of death in patients with advanced cancer. Recently, a high-fat diet was shown to specifically promote the metastatic potential of specific cancer cells in a CD36-dependent manner. However, the molecular basis of the fatty acid (FA)-induced upregulation of CD36 has remained unclear.

Methods: RT-qPCR, FACS analysis, immunoblotting and immunohistochemistry, as well as retrieving TCGA database, were carried out to quantitate CD36 expression in gastric cancer (GC) tissues and cell lines. Transwell assay and xenografts were used to assess cell metastasis abilities in vitro and in vivo after indicated treatment. Luciferase reporter assay was carried out to evaluate the changes in signaling pathways when O-GlcNAcylation level was increased in GC cells and in vitro O-GlcNAcylation assay was utilized for wild and mutant types of CD36 protein to explore the potential O-GlcNAcylation sites.

Results: High CD36 expression is a predictor of poor survival and promotes metastasis of GC cells and the use of neutralizing antibodies to block CD36 inhibits GC metastasis in mice. FA or a HFD promotes the metastatic potential of GC cells by upregulating CD36 via increasing the O-GlcNAcylation level. Increased O-GlcNAcylation levels promote the transcription of CD36 by activating the NF-κB pathway and also increase its FA uptake activity by directly modifying CD36 at S468 and T470.

Conclusion: FA-induced hyper-O-GlcNAcylation promotes the transcription and function of CD36 by activating the NF-κB pathway and directly modifying CD36 at S468 and T470, which drives GC metastasis.

CD36 tango in cancer: signaling pathways and functions

CD36, a scavenger receptor expressed in multiple cell types, mediates lipid uptake, immunological recognition, inflammation, molecular adhesion, and apoptosis. CD36 is a transmembrane glycoprotein that contains several posttranslational modification sites and binds to diverse ligands, including apoptotic cells, thrombospondin-1 (TSP-1), and fatty acids (FAs). Beyond fueling tumor metastasis and therapy resistance by enhancing lipid uptake and FA oxidation, CD36 attenuates angiogenesis by binding to TSP-1 and thereby inducing apoptosis or blocking the vascular endothelial growth factor receptor 2 pathway in tumor microvascular endothelial cells. Moreover, CD36-driven lipid metabolic reprogramming and functions in tumor-associated immune cells lead to tumor immune tolerance and cancer development. Notable advances have been made in demonstrating the regulatory networks that govern distinct physiological properties of CD36, and this has identified targeting CD36 as a potential strategy for cancer treatment. Here, we provide an overview on the structure, regulation, ligands, functions, and clinical trials of CD36 in cancer.

Decreased liver triglyceride content in adult rats exposed to protein restriction during gestation and lactation: roles of hepatic lipogenesis and lipid utilization in muscle and adipose tissue

Protein restriction throughout pregnancy and lactation reduces liver triglyceride (TG) content in adult male rat offspring. The study determined the contribution of hepatic lipogenesis to the reduction in liver TG content. Rats received either control or protein-restricted diets throughout pregnancy and lactation. Offspring were sacrificed on day 65. Hepatic fatty acid uptake and de novo fatty acid and TG biosynthesis were similar between control and low-protein (LP) offspring. These results indicate that hepatic lipogenesis cannot mediate the decrease in liver TG content in LP offspring. We then determined whether increased lipid utilization in adipose tissue and muscle was responsible for the decrease in liver TG content. There was suggestive evidence of increased sympathetic nervous system tone in epididymal adipose tissue of LP offspring that increased fatty acid uptake, TG lipolysis, and utilization of fatty acids in mitochondrial thermogenesis. Measurement of similar parameters demonstrated that such alterations do not occur in gastrocnemius muscle, another major lipid-utilizing tissue. Our results suggest that the decrease in liver TG content in LP offspring is likely due to increased diversion of fatty acids to white and brown adipose tissue depots and their enhanced utilization to fuel mitochondrial thermogenesis.

Determinants of nutrient limitation in cancer

Proliferation requires that cells accumulate sufficient biomass to grow and divide. Cancer cells within tumors must acquire a variety of nutrients, and tumor growth slows or stops if necessary metabolites are not obtained in sufficient quantities. Importantly, the metabolic demands of cancer cells can be different from those of untransformed cells, and nutrient accessibility in tumors is different than in many normal tissues. Thus, cancer cell survival and proliferation may be limited by different metabolic factors than those that are necessary to maintain noncancerous cells. Understanding the variables that dictate which nutrients are critical to sustain tumor growth may identify vulnerabilities that could be used to treat cancer. This review examines the various cell-autonomous, local, and systemic factors that determine which nutrients are limiting for tumor growth.

Targeting HIF-1α in combination with PPARα activation and postnatal factors promotes the metabolic maturation of human induced pluripotent stem cell-derived cardiomyocytes

Immature phenotypes of cardiomyocytes derived from human induced pluripotent stem cells (hiPSC-CMs) limit the utility of these cells in clinical application and basic research. During cardiac development, postnatal cardiomyocytes experience high oxygen tension along with a concomitant downregulation of hypoxia-inducible factor 1α (HIF-1α), leading to increased fatty acid oxidation (FAO). We hypothesized that targeting HIF-1α alone or in combination with other metabolic regulators could promote the metabolic maturation of hiPSC-CMs. We examined the effect of HIF-1α inhibition on the maturation of hiPSC-CMs and investigated a multipronged approach to promote hiPSC-CM maturation by combining HIF-1α inhibition with molecules that target key pathways involved in the energy metabolism. Cardiac spheres of highly-enriched hiPSC-CMs were treated with a HIF-1α inhibitor alone or in combination with an agonist of peroxisome proliferator activated receptor α (PPARα) and three postnatal factors (triiodothyronine hormone T3, insulin-like growth factor-1 and dexamethasone). HIF-1α inhibition significantly increased FAO and basal and maximal respiration of hiPSC-CMs. Combining HIF-1α inhibition with PPARα activation and the postnatal factors further increased FAO and improved mitochondrial maturation in hiPSC-CMs. Compared with mock-treated cultures, the cultures treated with the five factors had increased mitochondrial content and contained more cells with mitochondrial distribution throughout the cells, which are features of more mature cardiomyocytes. Consistent with these observations, a number of transcriptional regulators of mitochondrial metabolic processes were upregulated in hiPSC-CMs treated with the five factors. Furthermore, these cells had significantly increased Ca²⁺ transient kinetics and contraction and relaxation velocities, which are functional features for more mature cardiomyocytes. Therefore, targeting HIF-1α in combination with other metabolic regulators significantly improves the metabolic maturation of hiPSC-CMs.

Influence of Resveratrol on Sphingolipid Metabolism in Hepatocellular Carcinoma Cells in Lipid Overload State

Background:

Obesity is characterized by increased long chain fatty acids (LCFA) uptake and impaired lipid metabolism in hepatocytes. Consequently, an enhanced intracellular lipid content, including sphingolipids, may lead to lipotoxicity. It is believed that resveratrol (RSV), one of the most extensively studied plant-derived polyphenols, and its interaction with sphingolipid metabolism may constitute one of the major therapeutic targets for cancer and metabolic diseases treatment.

Objective:

The aim of this study was to ascertain, whether resveratrol may affect sphingolipid metabolic pathways, enzymes and transporters in a lipid overload state.

Methods:

The experiments were conducted on hepatocellular carcinoma cells (HepG2) incubated with RSV and/or Palmitic Acid (PA) at the concentration of 0.5 mM and 50 µM, respectively for 16h. Intra- and extracellular sphingolipid concentrations were assessed by high-performance liquid chromatography and gas liquid chromatography. Moreover, the expression of caspase 3, selected fatty acid transporters and sphingolipid metabolism pathway proteins were estimated by Western Blot.

Results:

RSV alone and together with PA significantly increased the intracellular concentration of ceramide, sphinganine and sphingosine as well as the expression of enzymes related to de novo ceramide synthesis pathway. Moreover, in our study, we observed augmented ceramide and sphingomyelin efflux into the incubation media in these groups. In addition, RSV substantially reduced intracellular triacylglycerols accumulation in lipid overload conditions.

Conclusion:

The above-mentioned findings suggest that RSV, at least partially, demonstrates a potential protective effect on HepG2 cells in a lipid overload state.

Gut microbiota signatures and lipids metabolism profiles by exposure to polyene phosphatidylcholine

The aim of the study was to address the causality links and identify specific features of the gut microbiota signatures contributing to host lipids metabolism in the presence or absence of polyene phosphatidylcholine (PPC) administration, and evaluate potential risk of PPC consumption. About 20 C57BL/6J mice were randomly allocated into two groups, normal diet group (CK) and PPC administration group (205.2 mg/kg). Compared with CK group, the contents of unsaturated fatty acids were increased and the saturated fatty acids were decreased in PPC group. The content of free fatty acids (FFA) and lipopolysaccharides (LPS) were significantly decreased (P < 0.05), and expression of carnitine palmitoyltransferase 1A (CPT1A), cluster of differentiation 36 (CD36), liver fatty acid binding protein (L-FABP), fatty acid transport protein 5 (FATP5), and fatty acid synthase (FASN) were significantly decreased in the mRNA and protein levels after treated by PPC (P < 0.05, P < 0.01). Also, we found that acetic acid in feces was significantly increased after consumption of PPC (P < 0.05). After PPC administration the relative abundances of Firmicutes and Clostridia were increased within the phylum level and the class level, respectively. Microbial abundances in genus level were dominated by Lachnospiraceae and Lachnospiraceae_NK4A136_group, whereas the proportion of sequences assigned to Bacteroidetes within the phylum level, class Bacteroidias and Mollicutes, order Anaeroplasmatalesl, genus Bacteroidales_S24-7_group were decreased in metagenomes of treated group with PPC and did not significantly influence on the accumulation of trimethylamine-N-oxide (TMAO). This study revealed that intake of PPC could regulate the gut microbiota signatures and lipids metabolism in mice without TMAO accumulations. © 2019 BioFactors, 45(3):439-449, 2019.

Molecular Mechanisms in Skeletal Muscle Underlying Insulin Resistance in Women Who Are Lean With Polycystic Ovary Syndrome

CONTEXT

Skeletal muscle molecular mechanisms underlying insulin resistance in women with polycystic ovary syndrome (PCOS) are poorly understood.

OBJECTIVE

To provide insight into mechanisms regulating skeletal muscle insulin resistance in women who are lean with PCOS.

PARTICIPANTS AND METHODS

A hyperinsulinemic-euglycemic clamp with skeletal muscle biopsies was performed. Thirteen women who are lean who have hyperandrogenism and PCOS and seven age- and body mass index-matched healthy control subjects were enrolled. Skeletal muscle protein expression and phosphorylation were analyzed by Western blotting and intramuscular lipid content was measured by thin-layer chromatography.

RESULTS

Women with PCOS had 25% lower whole-body insulin sensitivity and 40% lower plasma adiponectin concentration than in control subjects. Intramuscular triacylglycerol, sn-1.3 diacylglycerol, and ceramide contents in skeletal muscle were higher (40%, 50%, and 300%, respectively) in women with PCOS than in control subjects. Activation of insulin signaling did not differ between groups. In women with PCOS, the insulin-stimulated glucose oxidation was reduced and insulin-stimulated dephosphorylation of pyruvate dehydrogenase (PDH) Ser293 was absent. AMP-activated protein kinase (AMPK) α2 protein expression and basal Thr172 phosphorylation were 45% and 50% lower in women with PCOS than in control subjects, respectively.

CONCLUSIONS

Whole-body insulin resistance in women who are lean who have hyperandrogenism and PCOS was not related to changes in the proximal part of the insulin signaling cascade in skeletal muscle despite lipid accumulation. Rather, reduced insulin sensitivity was potentially related to plasma adiponectin levels playing a modulating role in human skeletal muscle via AMPK. Furthermore, abnormal PDH regulation may contribute to reduced whole-body metabolic flexibility and thereby insulin resistance.

Associations of plasma CD36 and body fat distribution

CONTEXT

CD36 is a class B scavenger-receptor involved in the uptake of fatty acids in liver and adipose tissue. It is unknown whether plasma CD36 levels are related to liver fat content or adipose tissue in the general population.

METHODS

We measured plasma CD36 from 575 participants of the community-based PopGen-cohort who underwent magnetic resonance imaging (MRI) to quantify visceral (VAT) and subcutaneous (SAT) adipose tissue and liver signal intensity (LSI), a proxy for liver fat content. Non-alcoholic fatty liver disease (NAFLD) was defined as LSI ≥3.0 in the absence of high alcohol intake. The relations between plasma CD36 and body mass index (BMI), VAT, SAT, LSI, and NAFLD were evaluated using multivariable-adjusted linear and logistic regression analysis.

RESULTS

Plasma CD36 concentrations were correlated with BMI (r=0.11; P=0.01), SAT (r=0.16; P<0.001), and VAT (r=0.15, P<0.001), but not with LSI (P=0.44). In multivariable-adjusted regression models, mean BMI values rose across CD36-quartiles (Q1: 27.8 kg/m2; Q4: 28.9 kg/m2; P-trend=0.013). Similarly, VAT (Q1: 4.13 dm3; Q4: 4.71 dm3; P-trend<0.001) and SAT (Q1: 7.61 dm3; Q4: 8.74 dm3; P-trend<0.001) rose across CD36 quartiles. Plasma CD36 concentrations were unrelated to LSI (P-trend=0.36), and NAFLD (P-trend=0.64). Participants with NAFLD and elevated alanine aminotransferase (ALT), a marker for liver damage, had higher CD36 compared to NAFLD participants with normal ALT.

CONCLUSIONS

Higher plasma concentrations of CD36 were associated with greater general and abdominal adiposity, but not with liver fat content or NAFLD in this community-based sample. However, plasma CD36 may reflect more severe liver damage in NAFLD.

A lipid-free and insulin-supplemented medium supports De Novo fatty acid synthesis gene activation in melanoma cells

While investigating the role played by de novo lipid (DNL) biosynthesis in cancer cells, we sought a medium condition that would support cell proliferation without providing any serum lipids. Here we report that a defined serum free cell culture medium condition containing insulin, transferrin and selenium (ITS) supports controlled study of transcriptional regulation of de novo fatty acid (DNFA) production and de novo cholesterol synthesis (DNCS) in melanoma cell lines. This lipid-free ITS medium is able to support continuous proliferation of several melanoma cell lines that utilize DNL to support their lipid requirements. We show that the ITS medium stimulates gene transcription in support of both DNFA and DNCS, specifically mediated by SREBP1/2 in melanoma cells. We further found that the ITS medium promoted SREBP1 nuclear localization and occupancy on DNFA gene promoters. Our data show clear utility of this serum and lipid-free medium for melanoma cancer cell culture and lipid-related areas of investigation.

miR-142 controls metabolic reprogramming that regulates dendritic cell activation

DCs undergo metabolic reprogramming from a predominantly oxidative phosphorylation (OXPHOS) to glycolysis to mount an immunogenic response. The mechanism underpinning the metabolic reprogramming remains elusive. We demonstrate that miRNA-142 (miR-142) is pivotal for this shift in metabolism, which regulates the tolerogenic and immunogenic responses of DCs. In the absence of miR-142, DCs fail to switch from OXPHOS and show reduced production of proinflammatory cytokines and the ability to activate T cells in vitro and in in vivo models of sepsis and alloimmunity. Mechanistic studies demonstrate that miR-142 regulates fatty acid (FA) oxidation, which causes the failure to switch to glycolysis. Loss- and gain-of-function experiments identified carnitine palmitoyltransferase -1a (CPT1a), a key regulator of the FA pathway, as a direct target of miR-142 that is pivotal for the metabolic switch. Thus, our findings show that miR-142 is central to the metabolic reprogramming that specifically favors glycolysis and immunogenic response by DCs.

HIF-1α Is a Metabolic Switch between Glycolytic-Driven Migration and Oxidative Phosphorylation-Driven Immunosuppression of Tregs in Glioblastoma

The mechanisms by which regulatory T cells (Tregs) migrate to and function within the hypoxic tumor microenvironment are unclear. Our studies indicate that specific ablation of hypoxia-inducible factor 1α (HIF-1α) in Tregs results in enhanced CD8+ T cell suppression versus wild-type Tregs under hypoxia, due to increased pyruvate import into the mitochondria. Importantly, HIF-1α-deficient Tregs are minimally affected by the inhibition of lipid oxidation, a fuel that is critical for Treg metabolism in tumors. Under hypoxia, HIF-1α directs glucose away from mitochondria, leaving Tregs dependent on fatty acids for mitochondrial metabolism within the hypoxic tumor. Indeed, inhibition of lipid oxidation enhances the survival of mice with glioma. Interestingly, HIF-1α-deficient-Treg mice exhibit significantly enhanced animal survival in a murine model of glioma, due to their stymied migratory capacity, explaining their reduced abundance in tumor-bearing mice. Thus HIF-1α acts as a metabolic switch for Tregs between glycolytic-driven migration and oxidative phosphorylation-driven immunosuppression.

Ethanol withdrawal mitigates fatty liver by normalizing lipid catabolism

We are investigating the changes in hepatic lipid catabolism that contribute to alcohol-induced fatty liver. Following chronic ethanol (EtOH) exposure, abstinence from alcohol resolves steatosis. Here, we investigated the hepatocellular events that lead to this resolution by quantifying specific catabolic parameters that returned to control levels after EtOH was withdrawn. We hypothesized that, after its chronic consumption, EtOH withdrawal reactivates lipid catabolic processes that restore lipostasis. Male Wistar rats were fed control and EtOH liquid diets for 6 wk. Randomly chosen EtOH-fed rats were then fed control diet for 7 days. Liver triglycerides (TG), lipid peroxides, key markers of fatty acid (FA) metabolism, lipophagy, and autophagy were quantified. Compared with controls, EtOH-fed rats had higher hepatic triglycerides, lipid peroxides, and serum free fatty acids (FFA). The latter findings were associated with higher levels of FA transporters (FATP 2, 4, and 5) but lower quantities of peroxisome proliferator-activated receptor-α (PPAR-α), which governs FA oxidation. EtOH-fed animals also had lower nuclear levels of the autophagy-regulating transcription factor EB (TFEB), associated with lower hepatic lipophagy and autophagy. After EtOH-fed rats were refed control diet for 7 days, their serum FFA levels and those of FATPs fell to control (normal) levels, whereas PPAR-α levels rose to normal. Hepatic TG and malondialdehyde levels in EtOH-withdrawn rats declined to near control levels. EtOH withdrawal restored nuclear TFEB content, hepatic lipophagy, and autophagy activity to control levels. EtOH withdrawal reversed aberrant FA metabolism and restored lysosomal function to promote resolution of alcohol-induced fatty liver. NEW & NOTEWORTHY Here, using an animal model, we show mechanisms of reversal of fatty liver and injury following EtOH withdrawal. Our data indicate that reactivation of autophagy and lysosome function through the restoration of transcription factor EB contribute to reversal of fatty liver and injury following EtOH withdrawal.

Incorporation of Omega-3 Fatty Acids Into Human Skeletal Muscle Sarcolemmal and Mitochondrial Membranes Following 12 Weeks of Fish Oil Supplementation

Fish oil (FO) supplementation in humans results in the incorporation of omega-3 fatty acids (FAs) eicosapentaenoic acid (EPA; C20:5) and docosahexaenoic acid (DHA; C20:6) into skeletal muscle membranes. However, despite the importance of membrane composition in structure–function relationships, a paucity of information exists regarding how different muscle membranes/organelles respond to FO supplementation. Therefore, the purpose of the present study was to determine the effects 12 weeks of FO supplementation (3g EPA/2g DHA daily) on the phospholipid composition of sarcolemmal and mitochondrial fractions, as well as whole muscle responses, in healthy young males. FO supplementation increased the total phospholipid content in whole muscle (57%; p < 0.05) and the sarcolemma (38%; p = 0.05), but did not alter the content in mitochondria. The content of omega-3 FAs, EPA and DHA, were increased (+3-fold) in whole muscle, and mitochondrial membranes, and as a result the omega-6/omega-3 ratios were dramatically decreased (-3-fold), while conversely the unsaturation indexes were increased. Intriguingly, before supplementation the unsaturation index (UI) of sarcolemmal membranes was ∼3 times lower (p < 0.001) than either whole muscle or mitochondrial membranes. While supplementation also increased DHA within sarcolemmal membranes, EPA was not altered, and as a result the omega-6/omega-3 ratio and UI of these membranes were not altered. All together, these data revealed that mitochondrial and sarcolemmal membranes display unique phospholipid compositions and responses to FO supplementation.

Prevention of Obesity and Hyperlipidemia by Heptamethoxyflavone in High-fat Diet-induced Rats

Polymethoxyflavones (PMFs) have been shown to prevent obesity, ameliorate type 2 diabetes, and regulate lipid metabolism in vitro and in vivo. However, little is known about the contribution of 3,5,6,7,8,3',4'-heptamethoxyflavone (HMF) to prevent obesity and regulate lipid metabolism in vivo. We aimed to investigate the potential efficacy of HMF on preventing obesity and hyperlipidemia in rats fed a high-fat diet (HFD) and its underlying mechanisms. Male Sprague-Dawley rats were fed a normal diet or an HFD with or without HMF (0.02%, 0.04% and 0.08%, w/w) for 6 weeks. The supplementation of HMF not only significantly decreased body weight gain (HFD, 336.50 ± 18.84 g; LHMF, 309.43 ± 20.74 g; MHMF, 296.83 ± 13.88 g; HHMF, 265.71 ± 19.09 g; respectively, p < 0.05) and adipose tissues weight ( p < 0.05), but also markedly lowered serum levels of total cholesterol, triacylglycerol, and low-density lipoprotein cholesterol ( p < 0.05) in the sixth week in a dose-dependent manner compared with the HFD group. HMF also significantly alleviated hepatic steatosis in the liver (liver weight g/100 g body weight of HFD, 4.86 ± 0.11%; LHMF, 4.02 ± 0.33%; MHMF, 4.05 ± 0.31%; HHMF, 3.72 ± 0.34%; respectively, p < 0.05). Furthermore, transcriptome analysis and real-time quantitative RT-PCR demonstrated that HMF supplementation markedly downregulated hepatic genes related to adipogenesis transcription and inflammatory responses, and significantly upregulated genes related to fatty acid oxidation and energy expenditure. These results indicated that HMF could effectively prevent obesity and hyperlipidemia by regulation of the expression of lipid metabolism-related and inflammatory response-related genes.

Fetuin-A modulates lipid mobilization in bovine adipose tissue by enhancing lipogenic activity of adipocytes

Fetuin-A (FetA) is an adipokine and free fatty acid (FFA) carrier linked to adipose tissue (AT) function in monogastrics and ruminants. In dairy cows, plasma and AT FetA decrease after parturition, coinciding with reduced lipogenesis and increased lipolysis. In monogastrics, FetA enhances lipogenesis, but its role on lipid mobilization of ruminants is unclear. We hypothesized that FetA modulates lipid mobilization in bovine AT by enhancing the lipogenic activity of adipocytes. Our objective was to determine the effects of FetA on lipogenesis and lipolysis in cultured primary adipocytes from dairy cows. Preadipocytes from the tailhead subcutaneous AT depot were induced to differentiate in a 7-d coculture in vitro model. The effects of FetA on lipolytic responses of adipocytes were evaluated after a 2-h β-adrenergic stimulation with 1 µM isoproterenol (ISO) alone or combined with 0.1 mg/mL of FetA (FetA+ISO), and in cells treated with medium alone (CON) or with 0.1 mg/mL of FetA (FetA). Lipogenic responses of adipocytes treated with CON or FetA from d 5 to 7 of differentiation were assessed by fatty acid (FA) uptake quantification and triacylglycerol (TAG) accumulation, and the gene and protein expression of lipogenic markers. Bovine adipocytes abundantly expressed FetA gene and protein and secreted 48 ± 3.5 ng/DNA relative fluorescence units (RFU). Adrenergic stimulation with ISO increased lipolysis compared with CON, as reflected in the release of glycerol (0.12 ± 0.04 vs. 0.04 ± 0.02 nM/DNA RFU) and FFA (15 ± 13 vs. 6.2 ± 2.4 nM/DNA RFU). Lipolysis induced by ISO was attenuated by the addition of FetA (FetA+ISO) as reflected by lower glycerol (0.06 ± 0.04 nM/DNA RFU) and FFA (5.7 ± 2.7 nM/DNA RFU) release compared with ISO alone. Compared with CON, FetA enhanced lipogenic responses as demonstrated by higher FA uptake and increased accumulation of TAG. Exposure to FetA upregulated 1-acylglycerol-3-phosphate acyltransferase-2 (AGPAT2) gene expression and protein content, as well as its activity. Adipocytes exposed to FetA increased the secretion of the metabolite of AGPAT2, phosphatidic acid. In conclusion, FetA attenuates lipolytic responses and enhances lipogenesis in bovine adipocytes. The upregulation of the rate-limiting lipogenic enzyme AGPAT2 by FetA suggests a potential pathway by which this adipokine promotes TAG synthesis in adipocytes. These findings suggest that FetA is a potential target for lipid mobilization modulation in AT of dairy cows.

Docosahexaenoic acid (22:6n-3) Ameliorated the Onset and Severity of Experimental Autoimmune Encephalomyelitis in Mice

Multiple sclerosis (MS) is a neurologic autoimmune disease, which is the leading cause of nontraumatic neurologic disability in young adults in United States and Europe. n-3 polyunsaturated fatty acids (PUFA) are reported to mitigate severity of this disease. Recent studies suggest that phospholipid (PL) form of dietary n-3 PUFA may lead to their higher tissue accretion than triacylglycerol (TAG) form. We compared efficacy of PL-docosahexaenoic acid (22:6n-3) (DHA) and TAG-DHA on onset and severity of experimental autoimmune encephalomyelitis (EAE) in a mouse model of MS. Female mice were fed low alpha-linolenic acid (18:3n-3) (ALA) diet (control) for 2 weeks and then fed either control, 0.3%, or 1.0% DHA (PL or TAG) for 4 weeks pre-EAE induction and 4 weeks post-EAE induction. The brain and spinal cord n-6:n-3 ratio was significantly lower in all mice fed DHA compared to control. EAE onset was delayed in mice fed both DHA forms and concentrations, except for 1% TAG-DHA. The inverse association between the EAE score and the brain DHA concentration was nonsignificant at the end of the study (p = 0.08). Daily EAE scores of mice fed different DHA diets did not differ from control, however, the score of all DHA groups combined during days 9-16 was lower (p = 0.028) compared to the control. During days 17-22, the EAE score trended lower in 0.3% TAG-DHA and during days 23-28, the EAE score trended lower in both PL-DHA groups than those in all other groups. These findings suggest that TAG-DHA may be more effective than PL-DHA in the early phases of EAE, and in the final outcome, PL-DHA may be more effective than TAG-DHA.

Fluorescent labelling of membrane fatty acid transporter CD36 (SR-B2) in the extracellular loop

Context

Upon palmitate oversupply, membrane fatty acid-transporter CD36 (SR-B2) permanently translocates from endosomal storage to the sarcolemma, inducing lipotoxicity. CD36 translocation results from endosomal alkalinisation elicited by palmitate-induced disattachment of the cytoplasmic V₁-subcomplex from the membrane-integrated V₀-subcomplex of vacuolar-type H⁺-ATPase.

Objective

Develop a CD36 fluorescent labeling technique as initial step towards live cell imaging.

Methods

Three human CD36 (hCD36) mutants were constructed via insertion of a tetracysteine motif at different positions within the extracellular domain. Constructs were lentivirally transduced for subsequent CD36 labeling with fluorescein-arsenical hairpin-binder (FlAsH). Cell imaging was combined with V₀/V₁ immunostaining and Western blotting.

Results

Transduction of hCD36-wildtype and mutants yielded corresponding proteins in HL-1 cardiomyocytes. Tetracysteine mutant-2 (hCD36-TC2) showed similar fatty acid uptake to wildtype. FlAsH staining revealed a speckled pattern reminiscent of endosomes. We found decreased V₁ co-localization with CD36 upon high-palmitate culturing. Conversely, V₀ consistently co-localized with CD36.

Conclusion

hCD36-TC2 is a possible candidate for application of biarsenical dyes in live imaging studies pending further investigation. Our data is compatible with V₀/V₁ disassembly in high-palmitate-treated cells.

Extracellular Fatty Acids Are the Major Contributor to Lipid Synthesis in Prostate Cancer

Prostate cancer cells exhibit altered cellular metabolism but, notably, not the hallmarks of Warburg metabolism. Prostate cancer cells exhibit increased de novo synthesis of fatty acids (FA); however, little is known about how extracellular FAs, such as those in the circulation, may support prostate cancer progression. Here, we show that increasing FA availability increased intracellular triacylglycerol content in cultured patient-derived tumor explants, LNCaP and C4-2B spheroids, a range of prostate cancer cells (LNCaP, C4-2B, 22Rv1, PC-3), and prostate epithelial cells (PNT1). Extracellular FAs are the major source (∼83%) of carbons to the total lipid pool in all cell lines, compared with glucose (∼13%) and glutamine (∼4%), and FA oxidation rates are greater in prostate cancer cells compared with PNT1 cells, which preferentially partitioned extracellular FAs into triacylglycerols. Because of the higher rates of FA oxidation in C4-2B cells, cells remained viable when challenged by the addition of palmitate to culture media and inhibition of mitochondrial FA oxidation sensitized C4-2B cells to palmitate-induced apoptosis. Whereas in PC-3 cells, palmitate induced apoptosis, which was prevented by pretreatment of PC-3 cells with FAs, and this protective effect required DGAT-1-mediated triacylglycerol synthesis. These outcomes highlight for the first-time heterogeneity of lipid metabolism in prostate cancer cells and the potential influence that obesity-associated dyslipidemia or host circulating has on prostate cancer progression. IMPLICATIONS: Extracellular-derived FAs are primary building blocks for complex lipids and heterogeneity in FA metabolism exists in prostate cancer that can influence tumor cell behavior.

Elevation of blood lipids in hepatocyte-specific fatty acid transport 4-deficient mice fed with high glucose diets

Fatty acid transport protein4 (FATP4) is upregulated in acquired and central obesity and its polymorphisms are associated with blood lipids and insulin resistance. Patients with FATP4 mutations and mice with global FATP4 deletion exhibit skin abnormalities characterized as ischthyosis prematurity syndrome (IPS). Cumulating data have shown that an absence of FATP4 increases the levels of cellular triglycerides (TG). However, FATP4 role and consequent lipid and TG metabolism in the hepatocyte is still elusive. Here, hepatocyte-specific FATP4 deficient (Fatp4^L-/-) mice were generated. When fed with chow, these mutant mice displayed no phenotypes regarding blood lipids. However when fed low-fat/high-sugar (HS) or high-fat/high-sugar (HFS) for 12 weeks, Fatp4^L-/- mice showed a significant increase of plasma TG, free fatty acids and glycerol when compared with diet-fed control mice. Interestingly, Fatp4^L-/- mice under HS diet had lower body and liver weights and they were not protected from HFS-induced body weight gain and hepatic steatosis. Male mutant mice were more sensitive to HFS diet than female mutant mice. Glucose intolerance was observed only in female Fatp4^L-/- mice fed with HS diet. Lipidomics analyses revealed that hepatic phospholipids were not disturbed in mutant mice under both diets. Thus, hepatic FATP4 deletion rendered an increase of blood lipids including glycerol indicating a preferential fatty-acid channeling to TG pools that are specifically available for lipolysis. Our results imply a possible risk of hyperlipidemia as a result of abnormal metabolism in liver in IPS patients with FATP4 mutations who consume high-sugar diets.