Increased Lipid Accumulation Research Articles

Novel evolved Yarrowia lipolytica strains for enhanced growth and lipid content under high concentrations of crude glycerol

BackgroundYarrowia lipolytica is a well-studied oleaginous yeast known for its ability to accumulate and store intracellular lipids, while growing on diverse, non-conventional substrates. Amongst them, crude glycerol, a low-cost by-product of the biodiesel industry, appears to be an interesting option for scaling up a sustainable single-cell oil production process. Adaptive laboratory evolution (ALE) is a powerful tool to force metabolic adaptations endowing tolerance to stressful environmental conditions, generating superior phenotypes with industrial relevance.ResultsY. lipolytica MUCL 28849 underwent ALE in a synthetic medium with increasing concentration of pure or crude glycerol as a stressing factor (9–20% v/v) for 520 generations. In one case of pure glycerol, chemical mutagenesis with ethyl methanesulfonate (EMS) was applied prior to ALE. Growth profile, biomass production and lipid content of 660 evolved strains (EVS), revealed 5 superior isolates; exhibiting from 1.9 to 3.6-fold increase of dry biomass and from 1.1 to 1.6-fold increase of lipid concentration compared to the parental strain, when grown in 15% v/v crude glycerol. NGS for differential gene expression analysis, showed induced expression in all EVS affecting nucleosomal structure and regulation of transcription. As strains differentiated, further changes accumulated in membrane transport and protein transport processes. Genes involved in glycerol catabolism and triacylglycerol biosynthesis were overexpressed in two EVS. Mismatches and gaps in the expressed sequences identified altered splicing and mutations in the EVS, with most of them, affecting different components of septin ring formation in the budding process. The selected YLE155 EVS, used for scale-up cultivation in a 3L benchtop bioreactor with 20% v/v crude glycerol, achieved extended exponential phase, twofold increase of dry biomass and lipid yields at 48 h, while citric acid secretion and glycerol consumption rates were 40% and 50% lower, respectively, compared to the parental strain, after 24 h of cultivation.ConclusionALE and EMS-ALE under increasing concentrations of pure or crude glycerol generated novel Y. lipolytica strains with enhanced biomass and lipid content. Differential gene expression analysis and scale-up of YLE155, illustrated the potential of the evolved strains to serve as suitable “chassis” for rational engineering approaches towards both increased lipid accumulation, and production of high-added value compounds, through efficient utilization of crude glycerol.

Design of a nanobiosystem with remote photothermal gene silencing in Chlamydomonas reinhardtii to increase lipid accumulation and production

Research development in the precise control of gene expression in plant cells is an emerging necessity that would lead to the elucidation of gene function in these biological systems. Conventional gene-interfering techniques, such as micro-RNA and short interfering RNA, have limitations in their ability to downregulate gene expression in plants within short time periods. However, nanotechnology provides a promising new avenue with new tools to overcome these challenges. Here, we show that functionalized gold nanoparticles, decorated with sense and antisense oligonucleotides (FANSAO), can serve as a remote-control optical switch for gene interference in photosynthetic plant cells. We demonstrate the potential of employing LEDs as optimal light sources to photothermally dehybridize the oligonucleotides on the surface of metallic nanostructures, consequently inducing regulation of gene expression in plant cells. We show the efficiency of metallic nanoparticles in absorbing light from an LED source and converting it to thermal energy, resulting in a local temperature increase on the surface of the gold nanoparticles. The antisense oligonucleotides are then released due to the opto-thermal heating of the nanobiosystem composed of the metallic nanoparticles and the sense-antisense oligonucleotides. By applying this approach, we silenced the Carnitine Acyl Carnitine Translocase genes at 90.7%, resulting in the accumulation of lipid bodies in microalgae cells. These results exhibit the feasibility of using functionalized gold nanoparticles with sense and antisense oligonucleotides to enhance nucleic acid delivery efficiency and, most importantly, allow for temporal control of gene silencing in plant cells. These nanobiosystems have broad applications in the development and biosynthesis of biofuels, pharmaceuticals, and specialized chemicals.

Impaired adipocyte SLC7A10 promotes lipid storage in association with insulin resistance and altered BCAA metabolism.

The neutral amino acid transporter SLC7A10/ASC-1 is an adipocyte-expressed gene with reduced expression in insulin resistance and obesity. Inhibition of SLC7A10 in adipocytes was shown to increase lipid accumulation despite decreasing insulin-stimulated uptake of glucose, a key substrate for de novo lipogenesis. These data imply that alternative lipogenic substrates to glucose fuel continued lipid accumulation during insulin resistance in obesity. We examined whether increased lipid accumulation during insulin resistance in adipocytes may involve alter flux of lipogenic amino acids dependent on SLC7A10 expression and activity, and whether this is reflected by extracellular and circulating concentrations of marker metabolites. In adipocyte cultures with impaired SLC7A10, we performed RNA-sequencing and relevant functional assays. By targeted metabolite analyses (GC-MS/MS), flux of all amino acids and selected metabolites were measured in human and mouse adipose cultures. Additionally, SLC7A10 mRNA levels in human subcutaneous adipose tissue (SAT) were correlated to candidate metabolites and adiposity phenotypes in two independent cohorts. SLC7A10 impairment altered expression of genes related to metabolic processes including branched-chain amino acid (BCAA) catabolism, lipogenesis and glyceroneogenesis. In 3T3-L1 adipocytes, SLC7A10 inhibition increased fatty acid uptake and cellular content of glycerol and cholesterol. SLC7A10 impairment in SAT cultures altered uptake of aspartate and glutamate, and increased the net uptake of BCAAs, while increasing the net release of the valine catabolite 3-hydroxyisobytsurate (3-HIB). In human cohorts, SLC7A10 mRNA correlated inversely with total fat mass, circulating TAG, BCAAs and 3-HIB. Reduced SLC7A10 activity strongly affects flux of BCAAs in adipocytes, which may fuel continued lipogenesis during insulin resistance, and be reflected in increased circulating levels of the valine-derived catabolite 3-HIB.

Adipokine gremlin-1 promotes hepatic steatosis via upregulation of ER stress by suppressing autophagy-mediated signaling.

Gremlin-1 (GR1) is a novel adipokine that is highly expressed in human adipocytes and has been shown to inhibit the BMP2/4-TGFb signaling pathway. It has an effect on insulin sensitivity. Elevated levels of Gremlin have been shown to lead to insulin resistance in skeletal muscle, adipocytes, and hepatocytes. In this study, we investigated the effect of GR1 on hepatic lipid metabolism under hyperlipidemic conditions and explored the molecular mechanisms associated with GR1 by in vitro and in vivo studies. We found that palmitate increased GR1 expression in visceral adipocytes. Recombinant GR1 increased lipid accumulation, lipogenesis, and ER stress markers in cultured primary hepatocytes. Treatment with GR1 increased EGFR expression and mTOR phosphorylation and reduced autophagy markers. EGFR or rapamycin siRNA reduced the effects of GR1 on lipogenic lipid deposition and ER stress in cultured hepatocytes. Administration of GR1 via the tail vein induced lipogenic proteins and ER stress while suppressing autophagy in the livers of experimental mice. Suppression of GR1 by in vivo transfection reduced the effects of a high-fat diet on hepatic lipid metabolism, ER stress, and autophagy in mice. These results suggest that the adipokine GR1 promotes hepatic ER stress due to the impairment of autophagy, ultimately causing hepatic steatosis in the obese state. The current study demonstrated that targeting GR1 may be a potential therapeutic approach for treating metabolic diseases, including metabolic-associated fatty liver disease (MAFLD).

Profiling the oxylipidome in aged mice after chronic ethanol feeding: Identifying lipid metabolites as drivers of hepatocyte stress.

The global population of people over the age of 65 is increasing and expected to reach 1.5 billion by 2050. While aging is associated with a number of chronic illnesses including dementia, the underlying contribution of alcohol misuse in the elderly is understudied. Long-term chronic alcohol misuse can lead to alcohol-associated liver disease, consisting of a spectrum of pathologies, including steatosis and cirrhosis; liver disease can be rapidly accelerated by non-resolving inflammation. Despite this knowledge, the mechanistic underpinnings of dysregulated host immunity and accelerated liver disease progression in the aged by alcohol is unknown. Alcohol misuse in the elderly is on the rise and aging is associated with progressive increases in pro-inflammatory cytokine production. The goals of the current study are to characterize bioactive lipid mediators of inflammation by making use of a murine model of ethanol-induced liver disease in 3-month-old and 20-month-old mice by quantitatively profiling selected oxylipins in liver, brain and plasma. Following chronic ethanol exposure, liver injury, steatosis, and senescence markers were robustly increased in aged mice compared to young adult mice. Expression of proinflammatory cytokines and lipid metabolizing enzymes were increased in liver by both age and ethanol feeding. Lipoxygenase-derived lipid metabolites 9- and 13-hydroxy-octadecadienoic acid and 15-hydroxyeicosatetraenoic acid were increased in liver and plasma in ethanol-fed aged mice and positively correlated with liver injury. In plasma, 9,10-dihydroxy-octadecenoic acid/epoxy-octadecenoic acid plasma ratios correlated with liver injury in ethanol-fed aged mice. Finally, 15-hydroxyeicosatetraenoic acid and 9,10-dihydroxy-octadecenoic acid positively correlated between liver and plasma. Importantly, leukotriene E4, 9,10-dihydroxy-octadecenoic acid and 15-hydroxyeicosatetraenoic acid increased lipid accumulation and ER stress in cultured AML12 hepatocytes. These data highlight the complexity of lipid metabolite networks but identify key mediators that may be used for diagnostic and prognostic markers in early stages of alcohol-related liver disease in patients of all ages.

P53 protects against alcoholic fatty liver disease via ALDH2 inhibition.

The tumor suppressor p53 is critical for tumor suppression, but the regulatory role of p53 in alcohol-induced fatty liver remains unclear. Here, we show a role for p53 in regulating ethanol metabolism via acetaldehyde dehydrogenase 2 (ALDH2), a key enzyme responsible for the oxidization of alcohol. By repressing ethanol oxidization, p53 suppresses intracellular levels of acetyl-CoA and histone acetylation, leading to the inhibition of the stearoyl-CoA desaturase-1 (SCD1) gene expression. Mechanistically, p53 directly binds to ALDH2 and prevents the formation of its active tetramer and indirectly limits the production of pyruvate that promotes the activity of ALDH2. Notably, p53-deficient mice exhibit increased lipid accumulation, which can be reversed by ALDH2 depletion. Moreover, liver-specific knockdown of SCD1 alleviates ethanol-induced hepatic steatosis caused by p53 loss. By contrast, overexpression of SCD1 in liver promotes ethanol-induced fatty liver development in wild-type mice, while it has a mild effect on p53-/- or ALDH2-/- mice. Overall, our findings reveal a previously unrecognized function of p53 in alcohol-induced fatty liver and uncover pyruvate as a natural regulator of ALDH2.

Liver fibrosis is a common pathological change in the liver of dairy cows with fatty liver

Fatty liver (i.e., hepatic lipidosis) is a prevalent metabolic disorder in dairy cows during the transition period, characterized by excess hepatic accumulation of triglyceride (TG), tissue dysfunction, and cell death. Detailed pathological changes, particularly hepatic fibrosis, during fatty liver remain to be determined. Liver fibrosis occurs as a consequence of liver damage, resulting from the excessive accumulation of extracellular matrix, which distorts the architecture of the normal liver, compromising its normal synthetic and metabolic functions. Thus, we aimed to investigate liver fibrosis status and its potential causal factors including oxidative stress, hepatocyte apoptosis, and production of inflammatory cytokines in the liver of cows with fatty liver. Forty-five dairy cows (parity, 3-5) were selected, and liver biopsy and blood were collected on the second week postpartum (days in milk, 10-14 d). On the basis of the degree of lipid accumulation in liver, selected cows were categorized into normal (n = 25; TG <1% wet wt), mild fatty liver (n = 15; 1% ≤ TG <5% wet wt), and moderate fatty liver (n = 5; 5% ≤ TG <10% wet wt). Compared with normal cows, blood concentrations of nonesterified fatty acids and β-hydroxybutyrate, along with alanine aminotransferase and aspartate aminotransferase activities, were greater in the cows with fatty liver (mild and moderate). Hepatic extracellular matrix deposition, as indicated by Picrosirius red staining, was greater in cows with fatty liver than those with normal ones. In addition, we observed an increased proportion of collagen type I fiber in extracellular matrix with increased lipid accumulation in the liver. Compared with normal cows, the area of α-smooth muscle actin (α-SMA)-positive staining along with the mRNA abundance of collagen type I α 1 (COL1A1), ACTA2 (gene encoding α-SMA), and transforming growth factor-β (TGFB) were greater in cows with fatty liver. Compared with normal cows, hepatic contents of malondialdehyde, glutathione disulfide, and 8-isoprostane were greater, whereas total antioxidant capacity, the hepatic content of glutathione, and activities of antioxidant indicators, including superoxide dismutase, glutathione peroxidase, and catalase, were lower in cows with fatty liver. The number of terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive cells and abundance of apoptosis-related molecules BAX, CASP3, CASP8, and CASP9 were greater in cows with fatty liver. However, mRNA abundance of the anti-apoptotic gene BCL2 did not differ. The mRNA abundance of pro-inflammatory cytokines including tumor necrosis factor-α (TNFA), interleukin-1β (IL1B), and interleukin-6 (IL6) was greater in the liver of cows with fatty liver. Overall, the present study indicated that fibrosis is a common pathological response to liver damage and is associated with oxidative stress, hepatocyte death, and inflammation.

Association between folate and non-alcoholic fatty liver disease among US adults: a nationwide cross-sectional analysis.

Association between folate and non-alcoholic fatty liver disease among US adults: a nationwide cross-sectional analysis.

Aging breaks liver vascular 'zone defense'.

Wang Lin and his colleagues explore how aging reprograms spatially unique pathways in liver endothelial cells to cause fibrosis. They find that loss of KIT in liver endothelial cells close to the central vein upregulates the chemokine receptor CXCR4 to stimulate inflammation, enhance fibrosis and increase lipid accumulation in aged liver.

Pre-Diabetes-Linked miRNA miR-193b-3p Targets PPARGC1A, Disrupts Metabolic Gene Expression Profile and Increases Lipid Accumulation in Hepatocytes: Relevance for MAFLD.

Distinct plasma microRNA profiles associate with different disease features and could be used to personalize diagnostics. Elevated plasma microRNA hsa-miR-193b-3p has been reported in patients with pre-diabetes where early asymptomatic liver dysmetabolism plays a crucial role. In this study, we propose the hypothesis that elevated plasma hsa-miR-193b-3p conditions hepatocyte metabolic functions contributing to fatty liver disease. We show that hsa-miR-193b-3p specifically targets the mRNA of its predicted target PPARGC1A/PGC1α and consistently reduces its expression in both normal and hyperglycemic conditions. PPARGC1A/PGC1α is a central co-activator of transcriptional cascades that regulate several interconnected pathways, including mitochondrial function together with glucose and lipid metabolism. Profiling gene expression of a metabolic panel in response to overexpression of microRNA hsa-miR-193b-3p revealed significant changes in the cellular metabolic gene expression profile, including lower expression of MTTP, MLXIPL/ChREBP, CD36, YWHAZ and GPT, and higher expression of LDLR, ACOX1, TRIB1 and PC. Overexpression of hsa-miR-193b-3p under hyperglycemia also resulted in excess accumulation of intracellular lipid droplets in HepG2 cells. This study supports further research into potential use of microRNA hsa-miR-193b-3p as a possible clinically relevant plasma biomarker for metabolic-associated fatty liver disease (MAFLD) in dysglycemic context.

2,4-Di-tert-butylphenol Induces Adipogenesis in Human Mesenchymal Stem Cells by Activating Retinoid X Receptors.

2,4-Di-tert-butylphenol (2,4-DTBP) is an important commercial antioxidant and a toxic natural secondary metabolite that has been detected in humans. However, there is scant information regarding its toxicological effects. We asked whether 2,4-DTBP is a potential obesogen. Using a human mesenchymal stem cell adipogenesis assay, we found that exposure to 2,4-DTBP led to increased lipid accumulation and expression of adipogenic marker genes. Antagonist assays revealed that 2,4-DTBP increased lipid accumulation by activating the peroxisome proliferator-activated receptor (PPAR) γ-retinoid X receptor (RXR) heterodimer. 2,4-DTBP likely activated the PPARγ/RXRα heterodimer by activating RXRα but not directly binding to PPARγ. We confirmed that 2,4-DTBP directly bound to RXRα by solving the crystal structure of this complex, then predicted and demonstrated that related compounds could also activate RXRα. Our study demonstrated that 2,4-DTBP and related chemicals could act as obesogens and endocrine disruptors via RXRs. These data showed that 2,4-DTBP belongs to a family of compounds whose endocrine-disrupting and obesogenic effects can be strongly modulated by their chemical composition. Structure-activity studies such as the present one could help guide the rational development of safer antioxidants that do not interact with important nuclear receptors having broad effects on human development and physiology.

BMP-7 Attenuates Sarcopenia and Adverse Muscle Remodeling in Diabetic Mice via Alleviation of Lipids, Inflammation, HMGB1, and Pyroptosis.

Diabetic myopathy involves hyperglycemia, oxidative stress, and inflammation. However, the role of hypercholesterolemia-induced inflammation-mediated pathological mechanisms leading to fibrosis, sarcopenia, deterioration of muscle, and muscle dysfunction in diabetes is not well understood. In this study, we investigated the novel role of bone morphogenetic protein-7 (BMP-7) in ameliorating metabolic alterations, inflammation, pyroptosis, TGF-β/SMAD cell signaling mechanisms, and progression of diabetic myopathy. C57BL/6J mice were treated with saline, streptozotocin (STZ), or STZ+BMP-7. Diabetes was confirmed by increased fasting glucose levels and a glucose tolerance test. Gastrocnemius muscle and blood samples were collected for lipid and tissue analysis using various methods. A significant increase in hyperglycemia resulted in an increase in lipid accumulation, monocyte infiltration, and inflammation, as well as an increase in pyroptotic markers and signaling markers in diabetic muscle myocytes. A structural analysis showed significant muscle loss, and increased muscle deterioration and fibrosis leading to muscle dysfunction. BMP-7 attenuated pathological processes that resulted in significantly improved muscle function. We report, for the first time, that increased hyperlipidemia aggravates inflammation-induced pyroptosis, resulting in significant muscle loss, sarcopenia, and adverse skeletal muscle remodeling in diabetic muscle myopathy. Interventional treatment with BMP-7 attenuates hypercholesterolemia-induced inflammation-mediated sarcopenia and adverse muscle remodeling, suggesting BMP-7 could be a potential treatment option for diabetic muscle myopathy.

Analysis of Neutral Lipid Accumulation and Lipotoxicity in Non-hepatocyte Liver Cells Under Free Fatty-acid Treatment

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) and its advanced form, nonalcoholic steatohepatitis (NASH), are prevalent liver diseases with no effective treatment available. NAFLD is marked by increased lipid accumulation in the hepatocytes, lobular inflammation and fibrosis. However, the effects of lipid accumulation in other hepatic lineage cells, such as liver endothelial cells (LEC), intrahepatic cholangiocytes (IHCHOLs), and hepatic stellate cells (HSCs), on NAFLD/NASH progression are less understood.&#x0D; METHODS: Human HSCs, IHCHOLs, and LECs were isolated from liver explants of healthy donors and further characterized with immunofluorescence staining. The cells were treated with different concentrations of free fatty acids (FFAs, oleic acid and palmitic acid 2:1) for 48 hours, and then examined for lipid accumulation with staining of BODIPY493/503. A cell viability assay and LDH cytotoxicity assay were performed. Real-time PCR was performed to monitor gene expression in LECs after treatment.&#x0D; RESULTS: Lipid accumulation confirmed by BODIPY493/503 staining was observed following treatment, especially with higher FFA concentrations. No statistically significant difference in cell viability or cytotoxicity of the cells was observed under different treatment concentrations of FFA. However, a negative trend in cell viability was observed with an increment of FFA dosage. FFA treatment upregulated the expression of the genes in LEC that are related to angiogenesis (CDH5), epithelial-mesenchymal transformation (TGF-β2 and TGF-β3), cellular stress (P53), inflammation (IL-32) and immunoglobular cell adhesion molecules (ICAM-1 and VCAM-1) that are key to monocyte adhesion to endothelial cells in response to a local inflammatory signal.&#x0D; CONCLUSION: Using an in vitro cellular model system, we examined lipid accumulation and cellular stress in different human liver cell types, especially LECs, under dose-dependent FFA treatment. This could be further developed to delineate adaptive responses within different hepatic lineage cells in the progression of NAFLD/NASH.&#x0D; IMPACT: A better understanding of the involvement of hepatocytes and other hepatic lineages in the progression of NAFLD/NASH will augment the development of targeted and effective treatments.

Role of acyl-coenzyme A: cholesterol transferase 1 (ACAT1) in retinal neovascularization

BackgroundWe have investigated the efficacy of a new strategy to limit pathological retinal neovascularization (RNV) during ischemic retinopathy by targeting the cholesterol metabolizing enzyme acyl-coenzyme A: cholesterol transferase 1 (ACAT1). Dyslipidemia and cholesterol accumulation have been strongly implicated in promoting subretinal NV. However, little is known about the role of cholesterol metabolism in RNV. Here, we tested the effects of inhibiting ACAT1 on pathological RNV in the mouse model of oxygen-induced retinopathy (OIR).MethodsIn vivo studies used knockout mice that lack the receptor for LDL cholesterol (LDLR−/−) and wild-type mice. The wild-type mice were treated with a specific inhibitor of ACAT1, K604 (10 mg/kg, i.p) or vehicle (PBS) during OIR. In vitro studies used human microglia exposed to oxygen–glucose deprivation (OGD) and treated with the ACAT1 inhibitor (1 μM) or PBS.ResultsAnalysis of OIR retinas showed that increased expression of inflammatory mediators and pathological RNV were associated with significant increases in expression of the LDLR, increased accumulation of neutral lipids, and formation of toxic levels of cholesterol ester (CE). Deletion of the LDLR completely blocked OIR-induced RNV and significantly reduced the AVA. The OIR-induced increase in CE formation was accompanied by significant increases in expression of ACAT1, VEGF and inflammatory factors (TREM1 and MCSF) (p < 0.05). ACAT1 was co-localized with TREM1, MCSF, and macrophage/microglia makers (F4/80 and Iba1) in areas of RNV. Treatment with K604 prevented retinal accumulation of neutral lipids and CE formation, inhibited RNV, and decreased the AVA as compared to controls (p < 0.05). The treatment also blocked upregulation of LDLR, ACAT1, TREM1, MCSF, and inflammatory cytokines but did not alter VEGF expression. K604 treatment of microglia cells also blocked the effects of OGD in increasing expression of ACAT1, TREM1, and MCSF without altering VEGF expression.ConclusionsOIR-induced RNV is closely associated with increases in lipid accumulation and CE formation along with increased expression of LDLR, ACAT1, TREM1, and MCSF. Inhibiting ACAT1 blocked these effects and limited RNV independently of alterations in VEGF expression. This pathway offers a novel strategy to limit vascular injury during ischemic retinopathy.Graphical

Chronic Exposure to Low-Molecular-Weight Polycyclic Aromatic Hydrocarbons Promotes Lipid Accumulation and Metabolic Inflammation.

2-naphthol is a low-molecular-weight (LMW) polycyclic aromatic hydrocarbon (PAH) and air pollutant associated with childhood obesity. There has been a recent emergence of studies on the consequences of PAHs on human health. Current epidemiological reports suggest LMW-PAHs may contribute to obesity incidences in children, yet most studies focus on high-molecular-weight PAHs. This study explores 2-naphthol's impact on obesity and obesity-associated metabolic disorders. To investigate 2-naphthol's effect on lipid metabolism and inflammation, we employed 3T3-L1 and BAT1 cell lines to model white and brown adipocytes, respectively, alongside a murine macrophage cell line (RAW264.7). We found that 2-naphthol increased the expression of key adipogenic and lipogenic genes while decreasing lipolytic gene expression in chronically treated 3T3-L1 and BAT1 adipocytes. In addition, chronic 2-naphthol treatment also suppressed adrenergic-stimulated thermogenic gene expression in BAT1 brown adipocytes. In consistence, an increase in lipid accumulation was demonstrated in BODIPY and Oil Red O-stained adipocytes. Additionally, 3T3-L1 adipocytes and RAW264.7 macrophages chronically exposed to 2-naphthol showed upregulated mRNA expression of major inflammatory cytokines (e.g., tumor necrosis factor α (Tnfα), interleukin-1β (Il-1β), and Il-6). In summary, chronic exposure to 2-naphthol stimulates lipid accumulation in adipocytes and inflammation in adipocytes and macrophages. These findings support previous research that demonstrates 2-naphthol has obesogenic potential.

Transcriptome-wide m6A modification mediates cardiotoxicity in mice after chronic exposure to microplastics

The widespread presence of microplastics (MPs) has garnered attention owing to their possible adverse effects. However, the cardiotoxicity of MPs and their underlying mechanism remains unclear. N6-methyladenosine (m6A) modification contributes to post-transcriptional modulation of gene expression, but whether this modification is relevant to MP-induced cardiotoxicity is unknown. First, we detected damage to the myocardial tissue among MP-exposed and -unexposed (control) mice by staining them with hematoxylin and eosin, Masson trichrome, and Oil Red O. Then, we comprehensively measured the transcriptome-wide m6A methylome and m6A-altered genes using high-throughput sequencing assays, such as methylated RNA immunoprecipitation sequencing and RNA sequencing. Our data indicated MP-induced myocardial inflammatory injury and histological alterations in vivo, evidenced by the severity of cardiac fibrosis and increased lipid accumulation. We found 878 increased and 316 decreased methylation peaks mostly distributed in the 3′ UTR among the MP-exposed group compared with the control group. We found 779 upregulated and 340 downregulated genes in the MP-exposed group. In addition, conjoint analysis of results from the two high-throughput sequencings showed that 109 and 11 hypermethylated genes were upregulated and downregulated, respectively; 12 and 21 hypomethylated genes were upregulated and downregulated, respectively. Results of the cross-link analysis showed that several potential signals, such as ECM–receptor interactions, cell adhesion molecules, cytokine–cytokine receptor interactions, and NF–κB signaling, contributed to MP-induced cardiotoxicity. Our findings indicated that m6A modifications of genes were involved in MP-induced cardiotoxicity and reported new information regarding the chronic cardiotoxicity caused by MP exposure in mice.

Effects of sulfur and phosphorus concentration on the lipid accumulation and fatty acid profile in Chlorella vulgaris (Chlorophyta).

Nutrient deficiency induces a variety of cellular responses, including an increase in lipid accumulation in microalgae. Nitrogen starvation is the most studied deprivation. Here, we determine the effects of phosphorus and sulfur limitation on lipid accumulation in Chlorella vulgaris. A set of 9 experiments were performed, varying the initial concentration of these nutrients (set to 0, 50, and 100% of their original composition in Bold's basal medium). According to our results, the variation of P and S modified the specific growth rate, lag phase, and cell generation time. The ratio of 50%P and 0%S significantly increased the total lipid concentration. The fatty acid profile was dominated by C16:0, C18:0, and C18:1; a considerable increase in C20:5 was observed with 0%P and 50%S and 0%P and 100%S. Regarding neutral lipids, the response surface methodology (RSM) indicates that the maximum was observed when S was between 40 and 60% and P was between 95 and 100%. Therefore, the enhanced production of lipids caused by P and S limitation may contribute to the efficient oil production useful for algal biofuels.

Supplementation with rumen-inert fat in the growing phase altered adipogenic gene expression and the size and number of adipocytes in Hanwoo steers.

We hypothesized that the provision of rumen-inert fat (RIF) to growing cattle (9 to 13 mo of age) would affect the expression of genes involved in lipid metabolism and thereby affect the size and number of adipocytes of steers slaughtered at 30 mo of age. Thirty steers with an average initial body weight (BW) of 239 ± 25 kg were allocated to six pens, balanced for BW and genetic merit for marbling, and assigned to one of two treatment groups: control (only basal diet) or test diet (basal diet with 200 g of RIF per day, on an as-fed basis) for 5 mo. Biopsy samples of longissimus lumborum (LM) muscle were then collected for analysis of fatty acid composition and gene expression. Both groups were then fed the same basal diets during the early and late fattening phases, without RIF, until slaughter (average shrunk BW = 759 kg). Supplementation with RIF increased the longissimus thoracis (LT) intramuscular fatty acid concentration at slaughter (P = 0.087) and numerically increased the quality grade score (P = 0.106). The LM intramuscular relative mRNA expression of genes such as PPARα, ZFP423 and SREBP1, FASN, SCD, FABP4, GPAT1, and DGAT2 were downregulated (P < 0.1) following RIF supplementation. Supplementation of RIF decreased (P < 0.1) diameter and concomitantly increased intramuscular adipocytes per viewing section at slaughter. This likely was caused by promotion of triacylglycerol hydrolysis during the growing phase. Another possible explanation is that the relative mRNA expression of gene ATGL was upregulated by RIF supplementation during the growing (P < 0.1) and the fattening phases (P < 0.05), while the genes associated with fatty acid uptake (FABP4) and esterification (DGAT2) were downregulated during the growing phase and upregulated (P < 0.1) during the fattening phase. This implies that the lipid turnover rate was higher for steers during the growing than fattening phase. This study demonstrated that RIF supplementation during the growing phase induced a carryover effect on the lipogenic transcriptional regulation involved in adipocyte lipid content of intramuscular adipose tissue; increased triacylglycerol hydrolysis during the growing phase subsequently was followed by increased lipid accumulation during the fattening phases.

Hepatic PTP4A1 ameliorates high-fat diet-induced hepatosteatosis and hyperglycemia by the activation of the CREBH/FGF21 axis.

Precise regulation of kinases and phosphatases is crucial for human metabolic homeostasis. This study aimed to investigate the roles and molecular mechanisms of protein tyrosine phosphatase type IVA1 (PTP4A1) in regulating hepatosteatosis and glucose homeostasis. Method: Ptp4a1-/- mice, adeno-associated virus encoding Ptp4a1 under liver-specific promoter, adenovirus encoding Fgf21, and primary hepatocytes were used to evaluate PTP4A1-mediated regulation in the hepatosteatosis and glucose homeostasis. Glucose tolerance test, insulin tolerance test, 2-deoxyglucose uptake assay, and hyperinsulinemic-euglycemic clamp were performed to estimate glucose homeostasis in mice. The staining, including oil red O, hematoxylin & eosin, and BODIPY, and biochemical analysis for hepatic triglycerides were performed to assess hepatic lipids. Luciferase reporter assays, immunoprecipitation, immunoblots, quantitative real-time polymerase chain reaction, and immunohistochemistry staining were conducted to explore the underlying mechanism. Results: Here, we found that deficiency of PTP4A1 aggravated glucose homeostasis and hepatosteatosis in mice fed a high-fat (HF) diet. Increased lipid accumulation in hepatocytes of Ptp4a1-/- mice reduced the level of glucose transporter 2 on the plasma membrane of hepatocytes leading to a diminution of glucose uptake. PTP4A1 prevented hepatosteatosis by activating the transcription factor cyclic adenosine monophosphate-responsive element-binding protein H (CREBH)/fibroblast growth factor 21 (FGF21) axis. Liver-specific PTP4A1 or systemic FGF21 overexpression in Ptp4a1-/- mice fed an HF diet restored the disorder of hepatosteatosis and glucose homeostasis. Finally, liver-specific PTP4A1 expression ameliorated an HF diet-induced hepatosteatosis and hyperglycemia in wild-type mice. Conclusions: Hepatic PTP4A1 is critical for regulating hepatosteatosis and glucose homeostasis by activating the CREBH/FGF21 axis. Our current study provides a novel function of PTP4A1 in metabolic disorders; hence, modulating PTP4A1 may be a potential therapeutic strategy against hepatosteatosis-related diseases.

PS-C06-4: RELATIONSHIP BETWEEN URINARY MICROALBUMIN AND LIPID ACCUMULATION PRODUCT AND VISCERAL ADIPOSITY INDEX IN PATIENTS WITH ESSENTIAL HYPERTENSION

Objective: To explore the relationship between urinary microalbumin and lipid accumulation product and visceral adiposity index in patients with essential hypertension. Design and method: A total of 463 essential hypertension patients admitted to the Department of Hypertension of the First Affiliated Hospital of Xinjiang Medical University from April 2020 to October 2021 were selected. Patients were grouped according to 24-hours urinary microalbumin and divided into normal 24-hours urinary microalbumin group and elevated 24-hours urinary microalbumin group to compare the clinical data of the two groups and analyze the risk factors of elevated urinary microalbumin. Results: The 24-hours urinary microalbumin was positively associated with lipid accumulation product and visceral adiposity index in patients with essential hypertension(all P &lt; 0.01). The risk of elevated 24-hours urinary microalbumin may increase with increasing lipid accumulation product,visceral adiposity index. After adjusting for age,sex,admission systolic blood pressure,admission diastolic blood pressure,body mass index,triglycerides,high density lipoprotein cholesterol,serum creatinine,the OR (95%CI) of lipid accumulation product in the fourth quantile group was 4.770 (1.680∼13.545) compared with the first quantile of lipid accumulation product. The OR (95%CI) values of visceral adiposity index in the second,third and fourth quartile groups were 3.364 (1.330∼8.512),3.440 (1.249∼9.472),and 5.213 (1.556∼17.461),compared with the first quartile group of visceral adiposity index. Analysis of the receiver operating characteristic curve suggested that the risk of elevated urinary microalbumin increases when the lipid accumulation product is greater than 32.236 and the visceral adiposity index is greater than 2.031. Conclusion: When the lipid accumulation product and visceral adiposity index increase in patients with essential hypertension, they may lead to an increased risk of increased urinary microalbumin.