acetyl-CoA Research Articles

Biosynthesis-Encoded Lipogenic Acetyl-CoA Measurement Using NMR Reveals Glucose-Driven Lipogenesis and Glutamine's Alternative Roles in Kidney Cancer.

Fatty acid de novo synthesis (FADNS) is a critical process in lipogenesis that is characteristically altered in clear cell renal cell carcinoma (ccRCC), which is the major type of kidney cancer. An important challenge in studying the FADNS process has been the accurate measurement of cytosolic lipogenic acetyl-CoA (AcCoA), the precursor in FADNS, due to its compartmentalization within cells. Here, we describe a novel NMR-based method to decode the isotopic enrichment of lipogenic AcCoA, which, as we demonstrated, is encoded in the simple signal ratios of the geminal methyl groups of lanosterol during its biosynthesis. The approach was validated based on the independence of the tracer enrichment and species along with the expected FADNS modulation using differentially enriched tracers and a well-studied drug. Application of this technique to 786-O ccRCC cells showed that glucose may serve as a major carbon source for lipogenic AcCoA in FADNS at physiological nutrient concentrations, at odds with previous studies that indicated glutamine's dominant role through reductive carboxylation under higher nutrient conditions. Further investigation into glutamine's alternative roles in ccRCC cells suggested its major involvement in the bioenergetic TCA cycle, pyrimidine synthesis, and glutathione synthesis, which is also critical in ccRCC growth. The glutamine-dependent glutathione synthesis was also suggested as a possible metabolic vulnerability compared to normal kidney cells using a glutathione synthesis inhibitor. The current study provides a simple tool for studying an important aspect of lipid metabolism and suggests translational implications for targeting glucose-driven lipogenesis and glutamine-supported glutathione synthesis in ccRCC.

Boosted Meat Flavor by the Metabolomic Effects of Nile Tilapia Dietary Inclusion of Zophobas atratus Larval Meal.

Zophobas atratus larval meal (ZLM) is a high-quality feed supplement with potential activities that can improve fish growth performance and promote meat quality. However, there have been limited recent studies investigating the metabolic effects of ZLM. Therefore, this study aims to uncover the metabolomic mechanism through which ZLM improves tilapia meat flavor using metabolomic strategies. In this study, soybean meal in the basal diets was replaced with 15%, 30%, or 60% ZLM, where anti-nutrient factors were destroyed by high temperature treatment. After being fed these ZLM supplements for 30 days, dorsal muscles were collected from tilapia for meat sensory evaluation tests. Liver samples were also collected for metabolomic analysis using the gas chromatography-mass spectrometry (GC-MS) platform and combined with biochemical assays to verify metabolism-related enzyme activities and reveal crucial metabolic pathways and critical biomarkers associated with ZLM's ability to improve meat flavor. In tilapia livers, ZLM enhanced the activity of enzymes involved in energy metabolism including succinate dehydrogenase (SDH), pyruvate dehydrogenase (PDH), α-ketoglutarate dehydrogenase (α-KGDH), NADP-malate dehydrogenase (NAD-MDH) and mitochondrial isocitrate dehydrogenase (ICDHm). This resulted in increased levels of reduced nicotinamide adenine dinucleotide (NADH), acetyl CoA and ATP which led to accumulation of flavor fatty acids such as arachidonic acid, linoleic acid (9,12-Octadecadienoic acid), linolenic acid (9,12,15-Octadecatrienoic acid) and oleic acid (9-Octadecenoic acid). Additionally, there was an increase in flavor nucleotides like guanosine adenosine-5'-monophosphate and uridine-5'-monophosphate while off-flavor metabolites like inosine and hypoxanthine decreased. Furthermore, beneficial metabolomic responses led to a decrease in off-flavor metabolites such as 2-methylisoborneol trimethylamine and geosmin while increasing umami metabolites like 2-methyl-3-furanthiol and nonanal. This metabolomic study demonstrates that inclusion of ZLM diets enhances the flavor profile of tilapia dorsal muscle. The accumulation of flavor compounds, coupled with a reduction in earthy taste and off-flavor metabolites, contributes to an improved meat flavor and freshness. Additionally, there is an increase in the levels of flavor-related amino acids and nucleotides. These previously unidentified metabolic effects highlight the potential significance of ZLM as a dietary supplement for enhancing the biosynthesis of flavor metabolites in tilapia.

Sensitivity of Southcentral U.S. Johnsongrass Accessions to Selected Herbicides

Abstract New technologies in grain sorghum allow for the use of multiple acetyl CoA carboxylase- (ACCase) or acetolactate synthase- (ALS) inhibiting herbicides for johnsongrass control. With the growing issue of herbicide resistance, producers need to understand which herbicides will successfully control johnsongrass accessions. To determine the efficacy of herbicides recently registered or ones with potential to become available for use in grain sorghum, johnsongrass seeds were collected from 2017 to 2021 in Arkansas, Kansas, Texas, and Oklahoma and were screened for sensitivity to fluazifop, quizalofop, nicosulfuron, and imazamox. Additionally, glyphosate sensitivity was evaluated because of its use before planting or postharvest. Quizalofop resulted in 100% mortality of all johnsongrass accessions. Of the johnsongrass accessions evaluated, 89% were completely controlled with glyphosate. The ALS inhibitors nicosulfuron and imazamox resulted in 100% mortality of all Oklahoma accessions, but failures occurred on samples from other states. One accession from Kansas, 12 from Texas, and eight from Arkansas were found to have reduced sensitivity to nicosulfuron and imazamox. If producers plan to plant grain sorghum in areas with johnsongrass populations, an ACCase-inhibitor herbicide will most likely provide effective control. Imazamox and nicosulfuron, in conjunction with the appropriate trait, can be utilized in areas with sensitive johnsongrass populations or where other sensitive grass species are present.

Mitochondria: the epigenetic regulators of ovarian aging and longevity.

Ovarian aging is a major health concern for women. Ovarian aging is associated with reduced health span and longevity. Mitochondrial dysfunction is one of the hallmarks of ovarian aging. In addition to providing oocytes with optimal energy, the mitochondria provide a co-substrate that drives epigenetic processes. Studies show epigenetic alterations, both nuclear and mitochondrial contribute to ovarian aging. Both, nuclear and mitochondrial genomes cross-talk with each other, resulting in two ways orchestrated anterograde and retrograde response that involves epigenetic changes in nuclear and mitochondrial compartments. Epigenetic alterations causing changes in metabolism impact ovarian function. Key mitochondrial co-substrate includes acetyl CoA, NAD+, ATP, and α-KG. Thus, enhancing mitochondrial function in aging ovaries may preserve ovarian function and can lead to ovarian longevity and reproductive and better health outcomes in women. This article describes the role of mitochondria-led epigenetics involved in ovarian aging and discusses strategies to restore epigenetic reprogramming in oocytes by preserving, protecting, or promoting mitochondrial function.

EXTH-64. MECHANISMS OF MITOCHONDRIAL COMPLEX-I SENSITIVITY IN GBM

Abstract The biguanide metformin that is widely used for the management of Type 2 diabetes is being evaluated as an anti-neoplastic agent in cancer trials including GBM (NCT02780024, NCT03243851). The mechanisms of action of metformin as an anti-neoplastic agent is still being investigated, but recent studies have unequivocally demonstrated that its therapeutic effects in tumor cell growth and signaling are dependent on inhibition of mitochondrial complex I. Based on the success of metformin in combination therapy in some cancers, new generation of mitochondrial complex I inhibitors (MCI-i) such as IM156, IACS-010759, are currently under investigation. Diffusion of metformin across the plasma membrane occurs slowly. Its entry is facilitated by two transporters OCT1 and OCT2 that are not well expressed outside the liver and kidney. This presents a problem due to its lack of accumulation in other tissues at therapeutic concentrations. Therefore, identification of tumor subtypes that respond better to lower concentrations of metformin may be leveraged for targeted metformin therapy. Metformin GBM trials may be unsatisfactory since there are no molecular markers to distinguish metformin responders from non-responders. Identification of molecular markers may greatly improve metformin and other MCI-i-based therapy in GBM. By examining TCGA data and experimental analysis, we have identified that PDHA, that catalyzes pyruvate to acetyl Co-A, is a predictive molecular marker for MCI-i sensitivity in GBM and potentially beyond GBM. PDHA expression varies widely in patient tumors, potentially due to differential methylation. We are performing joint pathway analysis by examining differentially expressed genes and stable isotope tracing studies to determine distinct metabolic signatures in the two subsets of GBM. We are also performing Classification And Regression Tree (CART) analysis on a cohort of sixty primary GBM lines and tissues to predict if PDHA expression provides a binary outcome for MCI-i sensitivity.

Muscle metabolism in response to oxidized fish oil feed in juvenile Nile tilapia

To investigate the effect of oxidized fish oil on fish muscle metabolic responses and flesh quality, Nile tilapia (Oreochromis niloticus) weighing 13.73 ± 0.31 g were fed two diets for 12 weeks: a fresh fish oil (FFO) and a highly oxidized fish oil (OFO) diet. The peroxide value of the FFO and OFO diets was 2.2 meq/kg and 120.6 meq/kg, respectively. The OFO diet resulted in a decrease in lower growth, muscularity, nutritional value of fatty acids in the muscle, and density of myofibers. In the OFO group, the mRNA expression levels of lipolysis genes lipoprotein lipase (lpl) and hormone - sensitive lipase(hsl) in the muscle were upregulated compared with the FFO group, while, the mRNA expression level of acetyl CoA carboxylase was downregulated. Additionally, under the positive ion mode, the levels of DHA deposition in phosphatidylcholine and phosphatidyl ethanolamine were reduced in the muscle of the OFO group compared to the FFO group. A total of 68 proteins were identified in the muscle, of which 42 were up-regulated and 26 were down-regulated. The KEGG pathway enrichment analysis revealed that the major pathways of the differentially abundant proteins were the Wnt signaling pathway, TGF-beta signaling pathway, and proteoglycans in cancer. In summary, the OFO diet negatively affected growth, muscularity, and nutritional value. It also inhibited the transformation of myofiber types and led to the apoptosis of myofibers.

Electrochemically Promoted Regioselective C3–H Trifluoro/Difluoromethylation of 2H-Indazoles at Room Temperature

AbstractA green and sustainable electrochemical approach is developed for the regioselective C3–H trifluoro/difluoromethylation of 2H-indazoles at room temperature. Relatively less expensive C-soft (+)/Ni-foam (–) electrodes are utilized to selectively functionalize the 2H-indazoles effectively by avoiding the use of any external oxidant and transition-metal salt. Moreover, along with the C3–H trifluoromethylation, for the very first time, direct C3–H difluoromethylation of 2-phenyl-2H-indazoles is accomplished. Diverse C3–H trifluoro/difluoromethylated 2H-indazoles having an array of functionalities are successfully synthesized in moderate to very good yields. As an application, a precursor of both an estrogen receptor ligand and an acetyl Co-A carboxylase inhibitor is synthesized. A plausible reaction mechanism is proposed based on control experiments and cyclic voltammetry studies.

Discovery and Characterization of BAY-184: A New Potent and Selective Acylsulfonamide-Benzofuran In Vivo-Active KAT6AB Inhibitor.

KAT6A and KAT6B genes are two closely related lysine acetyltransferases that transfer an acetyl group from acetyl coenzyme A (AcCoA) to lysine residues of target histone substrates, hence playing a key role in chromatin regulation. KAT6A and KAT6B genes are frequently amplified in various cancer types. In breast cancer, the 8p11-p12 amplicon occurs in 12-15% of cases, resulting in elevated copy numbers and expression levels of chromatin modifiers like KAT6A. Here, we report the discovery of a new acylsulfonamide-benzofuran series as a novel structural class for KAT6A/B inhibition. These compounds were identified through high-throughput screening and subsequently optimized using molecular modeling and cocrystal structure determination. The final tool compound, BAY-184 (29), was successfully validated in an in vivo proof-of-concept study.

Macrogenomic analysis of tolerance and degradation mechanisms of polycyclic aromatic hydrocarbon in carbon and nitrogen metabolic pathways and associated bacterial communities during endogenous partial denitrification

The effective production of NO2−-N through endogenous partial denitrification (EPD) provides a promising perspective for the broader adoption and application of anaerobic ammonia oxidation. However, the accumulation of polycyclic aromatic hydrocarbons (PAHs) in the environment may worsen the operational challenges of the EPD system. This study evaluated the resilience of the EPD system to the toxic impacts of phenanthrene (PHE) and anthracene (ANT) through macrogenomic analysis. A control group was maintained under identical conditions for comparison. The results revealed that PHE and ANT had a relatively minimal impact on NO3−-N transformation and organic matter removal but significantly affected PO43−-P removal and NO2−-N accumulation in the EPD process. The PHE system achieved a higher NO2−-N accumulation, with a maximum NO3−-N to NO2−-N conversion ratio of 90.08 %. In contrast, the ANT system exhibited higher efficiency in the PO43−-P removal, achieving a peak removal rate of 74.94 %. Macrogenomic analysis revealed that PAHs significantly enriched both denitrifying glycogen-accumulating organisms (including Candidatus_Competibacter) and denitrifying polyphosphate-accumulating organisms (such as Thauera, Candidatus_Contendobacter, and Candidatus_Accumulibacter). This enrichment stabilized these organisms, facilitating NO2−-N accumulation and PO43−-P removal. Metabolic pathway analysis indicated that PHE promoted the enrichment of NO3−-N reductase and inhibited NO2−-N reductase activity. However, ANT stimulated oxidative phosphorylation and the phosphate cycle. Moreover, PAH metabolites enhanced the expression of key genes encoding succinate dehydrogenase and isocitrate dehydrogenase in the tricarboxylic acid cycle within the EPD process, leading to increase the synthesis and utilization of acetyl coenzyme-A. Notably, significant differences were observed between the effects of PHE and ANT on these metabolic processes. This study provides new methods for treating PAH-containing wastewater through the combination of EPD and anaerobic ammonia oxidation.

Genomic and biochemical analysis of lipid biosynthesis in Cyanophora paradoxa: Limited role of chloroplast in fatty acid synthesis.

Archaeplastida, a group of photosynthetic organisms with primary plastids, consists of green algae (plus plants), red algae, and glaucophytes. In contrast to green and red algae, information on lipids and lipid biosynthesis still needs to be included in the glaucophytes. The chloroplast is the site of photosynthesis and fatty acid synthesis in all photosynthetic organisms known to date. However, the genomic data of the glaucophyte Cyanophora paradoxa suggested the lack of acetyl CoA carboxylase and most components of fatty acid synthase in the chloroplast. Instead, multifunctional fatty acid synthase and acetyl CoA carboxylase are likely to reside in the cytosol. To examine this hypothesis, we measured fatty acid synthesis in isolated chloroplasts and whole cells using stable isotope labeling. The chloroplasts had very low activity of fatty acid synthesis, if any. Most processes of fatty acid synthesis, including elongation and desaturation, must be performed within the cytosol, and the fatty acids imported into the chloroplasts are assembled into the chloroplast lipids by the enzymes common to other algae and plants. Cyanophora paradoxa is a rare organism in which fatty acid synthesis and photosynthesis are not tightly linked. This could question the common origin of these two biosynthetic processes in Archaeplastida.

Molecular mechanics studies of factors affecting overall rate in cascade reactions: Multi-enzyme colocalization and environment.

Millions of years of evolution have optimized many biosynthetic pathways by use of multi-step catalysis. In addition, multi-step metabolic pathways are commonly found in and on membrane-bound organelles in eukaryotic biochemistry. The fundamental mechanisms that facilitate these reaction processes provide strategies to bioengineer metabolic pathways in synthetic chemistry. Using Brownian dynamics simulations, here we modeled intermediate substrate transportation of colocalized yeast-ester biosynthesis enzymes on the membrane. The substrate acetate ion traveled from the pocket of aldehyde dehydrogenase to its target enzyme acetyl-CoA synthetase, then the substrate acetyl CoA diffused from Acs1 to the active site of the next enzyme, alcohol-O-acetyltransferase. Arranging two enzymes with the smallest inter-enzyme distance of 60 Å had the fastest average substrate association time as compared with anchoring enzymes with larger inter-enzyme distances. When the off-target side reactions were turned on, most substrates were lost, which suggests that native localization is necessary for efficient final product synthesis. We also evaluated the effects of intermolecular interactions, local substrate concentrations, and membrane environment to bring mechanistic insights into the colocalization pathways. The computation work demonstrates that creating spatially organized multi-enzymes on membranes can be an effective strategy to increase final product synthesis in bioengineering systems.

The role of ATP citrate lyase in myelin formation and maintenance.

Formation of myelin by Schwann cells is tightly coupled to peripheral nervous system development and is important for neuronal function and long-term maintenance. Perturbation of myelin causes a number of specific disorders that are among the most prevalent diseases affecting the nervous system. Schwann cells synthesize myelin lipids de novo rather than relying on uptake of circulating lipids, yet one unresolved matter is how acetyl CoA, a central metabolite in lipid formation is generated during myelin formation and maintenance. Recent studies have shown that glucose-derived acetyl CoA itself is not required for myelination. However, the importance of mitochondrially-derived acetyl CoA has never been tested for myelination in vivo. Therefore, we have developed a Schwann cell-specific knockout of the ATP citrate lyase (Acly) gene to determine the importance of mitochondrial metabolism to supply acetyl CoA in nerve development. Intriguingly, the ACLY pathway is important for myelin maintenance rather than myelin formation. In addition, ACLY is required to maintain expression of a myelin-associated gene program and to inhibit activation of the latent Schwann cell injury program.

Integration of metabolomic and transcriptomic analyses reveals novel regulatory functions of the ChREBP transcription factor in energy metabolism.

Carbohydrate Response Element-Binding Protein (ChREBP) is a transcription factor that activates key genes involved in glucose, fructose, and lipid metabolism in response to carbohydrate feeding, but its other potential roles in metabolic homeostasis have not been as well studied. We used liver-selective GalNAc-siRNA technology to suppress expression of ChREBP in rats fed a high fat/high sucrose diet and characterized hepatic and systemic responses by integrating transcriptomic and metabolomic analyses. GalNAc-siChREBP-treated rats had lower levels of multiple short-chain acyl CoA metabolites compared to rats treated with GalNAc-siCtrl containing a non-targeting siRNA sequence. These changes were related to a sharp decrease in free CoA levels in GalNAc-siChREBP treated-rats, accompanied by lower expression of transcripts encoding enzymes and transporters involved in CoA biosynthesis. These activities of ChREBP likely contribute to its complex effects on hepatic lipid and energy metabolism. While core enzymes of fatty acid (FA) oxidation are induced by ChREBP knockdown, accumulation of liver acylcarnitines and circulating ketones indicate diversion of acetyl CoA to ketone production rather than complete oxidation in the TCA cycle. Despite strong suppression of pyruvate kinase and activation of pyruvate dehydrogenase, pyruvate levels were maintained, likely via increased expression of pyruvate transporters, and decreased expression of lactate dehydrogenase and alanine transaminase. GalNAc-siChREBP treatment increased hepatic citrate and isocitrate levels while decreasing levels of distal TCA cycle intermediates. The drop in free CoA levels, needed for the 2-ketoglutarate dehydrogenase reaction, as well as a decrease in transcripts encoding the anaplerotic enzymes pyruvate carboxylase, glutamate dehydrogenase, and aspartate transaminase likely contributed to these effects. GalNAc-siChREBP treatment caused striking increases in PRPP and ZMP/AICAR levels, and decreases in GMP, IMP, AMP, NaNM, NAD(P), and NAD(P)H levels, accompanied by reduced expression of enzymes that catalyze late steps in purine and NAD synthesis. ChREBP suppression also increased expression of a set of plasma membrane amino acid transporters, possibly as an attempt to replenish TCA cycle intermediates. In sum, combining transcriptomic and metabolomic analyses has revealed regulatory functions of ChREBP that go well beyond its canonical roles in control of carbohydrate and lipid metabolism to now include mitochondrial metabolism and cellular energy balance.

Analysis of oil accumulation mechanisms in plasma induced mutant Scenedesmus strains compared to original Scenedesmus strains

Scenedesmus sp. is a species of the Scenedesmus genus within the phylum Chlorophyta, commonly found as a planktonic algal species in freshwater and known for its rapid growth rate. This study employs room-temperature, atmospheric-pressure plasma mutagenesis for the breeding of Scenedesmus sp., utilizing transcriptomic analysis to investigate the biosynthesis mechanism of triglycerides. Further analysis of differentially expressed genes in transcriptome by measuring the macroscopic biological indicators of mutant and original algal strains. The findings of the study suggest that the mutant strain's photosynthesis has been enhanced, leading to improved light energy utilization and CO2 fixation, thereby providing more carbon storage and energy for biomass and lipid production. The intensification of glycolysis and the TCA (tricarboxylic acid) cycle results in a greater shift in carbon flux towards lipid accumulation. An elevated expression level of related enzymes in starch and protein degradation pathways may enhance acetyl CoA accumulation, facilitating a larger substrate supply for fatty acid production and thereby increasing lipid yield.

Carthamus tinctorius L. (Safflower) Flower Extract Attenuates Hepatic Injury and Steatosis in a Rat Model of Type 2 Diabetes Mellitus via Nrf2-Dependent Hypoglycemic, Antioxidant, and Hypolipidemic Effects.

This study aimed to examine the hepatic and anti-steatotic protective effects of methanolic extract from Carthamus tinctorius (safflower) flowers (SFFE), using a rat model of type 2 diabetes mellitus (T2DM), and to examine the molecular mechanisms underlying these effects. Adult male Wistar rats were used for this study. First, T2DM was induced in some rats by feeding them a high-fat diet (HFD) for 4 weeks, followed by a single dose of streptozotocin (STZ) (35 mg/kg, i.p.). Experimental groups included the following five groups (n = 8 in each): control, control + SFFE, T2DM, T2DM + SFFE, and T2DM + SFFE + brusatol (an Nrf2 inhibitor, 2 mg/kg, i.p.). SFFE was administered at a concentration of 300 mg/kg, and all experiments concluded after 8 weeks. Treatments with SFFE significantly reduced fasting blood glucose levels, free fatty acids (FFAs), cholesterol, triglycerides, and low-density lipoprotein cholesterol in both the control and T2DM rats, but they failed to reduce fasting insulin levels in these groups. SFFE treatments also improved the liver structure and reduced hepatocyte vacuolization and hepatic levels of triglycerides and cholesterol in T2DM rats, in addition to increasing the hepatic mRNA levels of keap1 and the cytoplasmic levels and nuclear activities of Nrf2 in both the control and T2DM rats. SFFE also stimulated the expression levels of PPARα and CPT-1 but reduced the malondialdehyde (MDA), mRNA levels of SREBP1, fatty acid synthase, and acetyl CoA carboxylase in both the control and T2DM rats; meanwhile, it reduced hepatic mRNA and the nuclear activities of NF-κB and increased levels of glutathione, superoxide dismutase, and heme oxygenase-1 in the livers of both groups of treated rats. Furthermore, SFFE suppressed the levels of caspase-3, Bax, tumor necrosis factor-α, and interleukin-6 in the T2DM rats. Treatment with brusatol prevented all of these effects of SFFE. In conclusion, SFFE suppresses liver damage and hepatic steatosis in T2DM through Nrf2-dependent hypoglycemic, antioxidant, anti-inflammatory, and hypolipidemic effects.

Zinc oxide nanoparticles cause hepatotoxicity in rare minnow (Gobiocypris rarus) via ROS-mediated oxidative stress and apoptosis activation and inhibition of lipid peroxidation

Zinc oxide nanoparticles (ZnO NPs) measuring 30 ± 10 nm in diameter are utilized in various applications, including batteries, plastics, ceramics, cosmetics, flame retardants, and food. However, their potential impact and risk on aquatic ecosystems remain unclear. This study examined the hepatotoxic effects of dietary ZnO NPs in rare minnow. Three hundred rare minnows were fed diets containing 0 mg/kg, 20 mg/kg and 60 mg/kg of ZnO NPs for 60 days, with hepatotoxicity assessments at 15-day intervals. The histological data showed that ZnO NPs severely damage liver tissues, causing cytoplasmic vacuolization and irregular or missing nuclei. The treatment groups showed a significant rise in the liver injury index (P < 0.05). Moreover, there was a notable increase in zinc accumulation in the ZnO NPs groups compared to the control group (P < 0.05). ZnO NPs also reduced body weight and hepato-somatic index (HSI) in rare minnows. The enzyme activity results showed elevated levels of reactive oxygen species (ROS), total cholesterol (T-CHO), triglyceride (TG), acetyl Coa carboxylase (ACC), and fatty acid synthase (FAS) in the ZnO NPs fed groups, while total antioxidant capacity (T-AOC) and malondialdehyde (MDA) decreased. Further investigation found that accumulation of ZnO NPs in the liver tissues up-regulated the levels of genes related to antioxidant (mn-sod, cat and nf-κb), pro-apoptotic (bax) and lipogenesis (gpat3, dgat1a and dgat1b), while down-regulating genes associated with lipid catabolism (cpt1 and tpi1). These findings suggest that dietary ZnO NPs cause hepatotoxicity by inducing oxidative stress through ROS, triggering apoptosis, and inhibiting lipid peroxidation. The results indicate that ZnO NPs may pose a significant threat to aquatic animals and ecosystems.

Abstract Tu110: CD36-Mediated Transendothelial Fatty Acid Transport Determines Cardiomyocyte Uptake and is Critical to Limiting a Lipotoxic Ceramide Profile and Supporting Cardiac Function during Pathological Stress.

The heart primarily relies on long chain fatty acid oxidation (LCFA) to meet ATP demand. CD36, is a transmembrane glycoprotein transferase for LCFA uptake widely expressed in several cell types including endothelial cells (ECs), cardiomyocytes (CMs), skeletal myocytes, adipocytes, and monocyte/macrophages. Notably, genetic deficiency of CD36 in humans is associated with hypertrophic cardiomyopathy. The role of CD36 in transendothelial LCFA delivery to CMs under physiologic vs pathologic conditions is unknown. We explored consequences of EC-specific CD36 deletion (EC-CD36 KO mice) on the cardiac response to pressure overload. Lack of EC-CD36 increased severity of left ventricular hypertrophy (LVH), and systolic and diastolic dysfunction at 8 weeks of pressure overload via transverse aortic constriction (TAC), with increases in HW:TL ratio, LV mass by echo, reduced EF (p&lt;0.05), and elevated E/E’ in EC-CD36-KO vs. flox/flox littermate controls (f/f) (p&lt;0.5) (Fig 1). Dynamic mode 13 C NMR revealed delayed 13 C LCFA uptake kinetics (time constant, τ) in CMs of isolated, sham and TAC EC-CD36 KO hearts provided 13 C palmitate + 13 C oleate (0.02 mM each) + 10 mM glucose + 1 mM lactate (Fig 2). 13 C LCFA esterification into triglyceride (TG) was also reduced in EC-CD36-KO vs f/f controls, but without evidence for an additional effect of TAC. The contribution of 13 C LCFA to acetyl CoA entry into oxidation via the TCA cycle, was reduced by lack of EC-CD36 in sham and TAC hearts (p&lt;0.0001) (Fig 2). Consistent with diminished LCFA oxidation, phosphocreatine (PCr) to ATP ratio was also compromised in EC-CD36-KO-TAC hearts (p&lt;0.05). Lack of EC-CD36 during TAC increased 13 C LCFA trafficking to lipotoxic C16 ceramide in EC-CD36 KO hearts (Fig 3). CD36 in ECs is critical to LCFA delivery to CMs during pathological stress on the heart. The imbalance in intramyocellular LCFA dynamics due to restricted transendothelial delivery of LCFA to CMs increased lipotoxic ceramide formation. Thus, EC CD36 is critical to the adaptive cardiac response to pathological stress, and the absence of EC CD36-dependent delivery of LCFA to CMs exacerbates reduced energy potential, adverse cardiac remodeling, and dysfunction during afterload stress.

Abstract Tu125: Loss of mitochondrial magnesium leads to hepatic ketogenic insufficiency and accelerates the progression of cardiac hypertrophy

Magnesium (Mg 2+ ) is an abundant intracellular divalent cation and is an important co-factor. Like calcium, Mg 2+ is also compartmentalized to mitochondria. Mrs2 is the only known molecular machinery associated with mitochondrial Mg 2+ influx. Although we know that Mg 2+ plays a crucial role in cellular homeostasis, our understanding of how mMg 2+ homeostasis alters the metabolic state of the cell remains incomplete. To begin elucidating the importance of mMg 2+ , we made a liver-specific Mrs2 knockout mouse model (Mrs2 Dhep ) using the Cre-loxP system. Since liver is the central hub of lipid metabolism, we hypothesized that loss of mitochondrial Mg 2+ could alter hepatic lipid homeostasis. Enigmatically we observed increased hepatic lipid accumulation, in spite of increased PPARa activation and Fatty acid oxidation (FAO). In our previous work we showed in Mrs2 Dhep the FAO-derived acetyl CoA to be channeled to de novo lipogenesis (DNL) via cataplerosis, instead of ketogenesis. Further, our results show markedly blunted ketonemia in Mrs2 Dhep revealing a state of ketogenic insufficiency. In the presence of increased ketone bodies (KB), normal hearts preferentially use both KB and FAO while glucose metabolism tend to be reduced. During the progression of heart failure (HF), the failing heart depends on alternate ATP generating substrates like KB as there is a metabolic deficit in both FAO and glucose metabolism. Because we saw a decrease in the KB, we hypothesize that hepatic ketogenic insufficiency will lead to cardiac hypertrophy and heart failure in pressure overload model due to energy insufficiency. Interestingly we found the heart weight and the heart to body weight ratio, left ventricular (LV) wall thickness, expression of genes linked to cardiac hypertrophy to be increased in Mrs2 Dhep compared to control. We also observed an adverse structural remodeling of LV and LV dysfunction. Masson’s trichrome staining showed increased collagen deposition and fibrosis in the Mrs2 Dhep mice when compared to the control. Our results show altered hepatic mitochondrial Mg 2+ homeostasis to have profound direct effect on hepatic lipid metabolism and indirect inter-organ effect on the heart following pressure overload.

Nuclear pyruvate dehydrogenase complex regulates histone acetylation and transcriptional regulation in the ethylene response.

Ethylene plays its essential roles in plant development, growth, and defense responses by controlling the transcriptional reprograming, in which EIN2-C-directed regulation of histone acetylation is the first key step for chromatin to perceive ethylene signaling. But how the nuclear acetyl coenzyme A (acetyl CoA) is produced to ensure the ethylene-mediated histone acetylation is unknown. Here we report that ethylene triggers the accumulation of the pyruvate dehydrogenase complex (PDC) in the nucleus to synthesize nuclear acetyl CoA to regulate ethylene response. PDC is identified as an EIN2-C nuclear partner, and ethylene triggers its nuclear accumulation. Mutations in PDC lead to an ethylene hyposensitivity that results from the reduction of histone acetylation and transcription activation. Enzymatically active nuclear PDC synthesizes nuclear acetyl CoA for EIN2-C-directed histone acetylation and transcription regulation. These findings uncover a mechanism by which PDC-EIN2 converges the mitochondrial enzyme-mediated nuclear acetyl CoA synthesis with epigenetic and transcriptional regulation for plant hormone response.

Arecoline inhibits the growth of Spodoptera litura by inducing intestinal metabolic dysfunction

Arecoline (ACL), an active constituent derived from Areca catechu L., exerts various pharmacological effects and serves as a potential plant-based insecticide. However, the effects of ACL on Spodoptera litura, an important and widely distributed agricultural pest, remain unknown. This study aimed to elucidate the mechanism underlying ACL-induced toxicity and its inhibitory effects on larval growth and development through intestinal pathology observations, intestinal transcriptome sequencing, intestinal digestive enzyme activity analysis. The results indicated that ACL exposure leads to pathological alterations in the S. litura midgut. Furthermore, the detection of digestive enzyme activity revealed that ACL inhibits the activities of acetyl CoA carboxylase, lipase, α-amylase, and trypsin. Simultaneously, upregulation of superoxide dismutase activity and downregulation of malondialdehyde levels were observed after ACL exposure. Transcriptome analysis identified 1118 genes that were significantly differentially expressed in the midgut after ACL exposure, potentially related to ACL toxic effects. Notably, ACL treatment downregulated key enzymes involved in lipid metabolism, such as fatty acid binding protein 2-like, pancreatic triacylglycerol lipase-like, pancreatic lipid-related protein 2-like, and fatty acid binding protein 1-like. Taken together, these results suggest that ACL induces midgut damage and impedes larval growth by suppressing digestive enzyme activity in the intestine. These findings can aid in the development of environmentally friendly plant-derived insecticides, utilizing ACL to effectively combat S. litura proliferation.