malonyl-CoA Research Articles

Regulatory role of microcystin in the response of microcystin-producing cyanobacteria to elevated CO2: Insights from metabolic profiling

The regulatory role of microcystin in the response of microcystin-producing cyanobacteria to elevated CO2 remains poorly understood. To address this gap, this study compared the responses of wild-type toxic Microcystis PCC 7806 and its mcyB-knockout mutant to elevated CO2 using metabolomic profiling under nitrogen (N)-rich and N-poor conditions. Under N-poor conditions, elevated CO2 promoted carbohydrate synthesis and tricarboxylic acid cycle in both strains, without affecting their growth. Under N-rich conditions, both strains exhibited increased biomass with rising CO2 levels, attributed to enhanced carbohydrate synthesis, tricarboxylic acid cycle, glutamate-glutamine cycle, purine synthesis, and arginine synthesis. However, compared to the mutant, the proliferation of wild-type toxic Microcystis was less stimulated by elevated CO2. The difference was associated with its reduced activity in the pentose phosphate pathway, likely linked to microcystin synthesis. Besides, the difference was related to higher utilization of glutamate, arginine, and aspartate due to increased microcystin production, indicating the regulatory role of microcystin in the response of microcystin-producing cyanobacteria to elevated CO2. Importantly, elevated CO2 could enhance microcystin synthesis by promoting the production of carbon backbones (malonyl CoA), amino acids (including arginine, glutamate and aspartate) and methyl donors (S-adenosylmethionine) of the wild-type toxic Microcystis PCC 7806. Notably, sufficient nitrogen sources were required for increased amino acid and methyl donors synthesis at high CO2 concentration. The discovery revealed underlying mechanisms behind the potential for elevated CO2 levels to increase toxicity risk associated with Microcystis blooms.

HMGR and CHS gene cloning, characterizations and tissue-specific expressions in Polygala tenuifolia Willd.

Triterpenoid saponins and flavonoids have several pharmacological activities against P. tenuifolia. The 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) and chalcone synthase (CHS) are the rate-limiting enzymes of triterpenoid saponin and flavonoid biosynthesis, respectively. In this study, HMGR and CHS genes were cloned from P. tenuifolia, and their bioinformatics analyses and tissue-specific expression were investigated. The results showed that the HMGR and CHS genes were successfully cloned, separately named the PtHMGR gene (NCBI accession: MK424118) and PtCHS gene (NCBI accession: MK424117). The PtHMGR gene is 2323 bp long, has an open reading frame (ORF) of 1782 bp, and encods 593 amino acids. The PtCHS gene is 1633 bp long with an ORF of 1170 bp, encoding 389 amino acids. PtHMGR and PtCHS were both hydrophobic, not signal peptides or secreted proteins, containing 10 conserved motifs. PtHMGR and PtCHS separately showed high homology with HMGR and CHS proteins from other species, and their secondary structures mainly included α-helix and random curl. The tertiary structure of PtHMGR was highly similarity to that the template 7ULI in RCSB PDB with 92.0% coverage rate. The HMG-CoA-binding domain of PtHMGR is located at 173-572 amino acid residues, including five bound sites. The tertiary structure of PtCHS showed high consistency with the template 1I86 in RCSB PDB with 100% coverage rate, contained malonyl CoA and 4-coumaroyl-CoA linkers. The expression of PtHMGR and PtCHS is tissue-specific. PtHMGR transcripts were mainly accumulated in roots, followed by leaves, and least in stems, and were significantly positively correlated with the contents of total saponin and tenuifolin. PtCHS was highly expressed in the stems, followed by the leaves, with low expression in the roots. PtCHS transcripts showed a significant positive correlation with total flavonoids content, however, they were significantly negatively correlated with the content of polygalaxanthone III (a type of flavonoids). This study provided insight for further revealing the roles of PtHMGR and PtCHS.

Integrating genomic and multiomic data for Angelica sinensis provides insights into the evolution and biosynthesis of pharmaceutically bioactive compounds

Angelica sinensis roots (Angelica roots) are rich in many bioactive compounds, including phthalides, coumarins, lignans, and terpenoids. However, the molecular bases for their biosynthesis are still poorly understood. Here, an improved chromosome-scale genome for A. sinensis var. Qinggui1 is reported, with a size of 2.16 Gb, contig N50 of 4.96 Mb and scaffold N50 of 198.27 Mb, covering 99.8% of the estimated genome. Additionally, by integrating genome sequencing, metabolomic profiling, and transcriptome analysis of normally growing and early-flowering Angelica roots that exhibit dramatically different metabolite profiles, the pathways and critical metabolic genes for the biosynthesis of these major bioactive components in Angelica roots have been deciphered. Multiomic analyses have also revealed the evolution and regulation of key metabolic genes for the biosynthesis of pharmaceutically bioactive components; in particular, TPSs for terpenoid volatiles, ACCs for malonyl CoA, PKSs for phthalide, and PTs for coumarin biosynthesis were expanded in the A. sinensis genome. These findings provide new insights into the biosynthesis of pharmaceutically important compounds in Angelica roots for exploration of synthetic biology and genetic improvement of herbal quality.

Systems biology of industrial oxytetracycline production in Streptomyces rimosus: the secrets of a mutagenized hyperproducer

BackgroundOxytetracycline which is derived from Streptomyces rimosus, inhibits a wide range of bacteria and is industrially important. The underlying biosynthetic processes are complex and hinder rational engineering, so industrial manufacturing currently relies on classical mutants for production. While the biochemistry underlying oxytetracycline synthesis is known to involve polyketide synthase, hyperproducing strains of S. rimosus have not been extensively studied, limiting our knowledge on fundamental mechanisms that drive production.ResultsIn this study, a multiomics analysis of S. rimosus is performed and wild-type and hyperproducing strains are compared. Insights into the metabolic and regulatory networks driving oxytetracycline formation were obtained. The overproducer exhibited increased acetyl-CoA and malonyl CoA supply, upregulated oxytetracycline biosynthesis, reduced competing byproduct formation, and streamlined morphology. These features were used to synthesize bhimamycin, an antibiotic, and a novel microbial chassis strain was created. A cluster deletion derivative showed enhanced bhimamycin production.ConclusionsThis study suggests that the precursor supply should be globally increased to further increase the expression of the oxytetracycline cluster while maintaining the natural cluster sequence. The mutagenized hyperproducer S. rimosus HP126 exhibited numerous mutations, including large genomic rearrangements, due to natural genetic instability, and single nucleotide changes. More complex mutations were found than those typically observed in mutagenized bacteria, impacting gene expression, and complicating rational engineering. Overall, the approach revealed key traits influencing oxytetracycline production in S. rimosus, suggesting that similar studies for other antibiotics could uncover general mechanisms to improve production.

Chemistry and Biological Activities of Cannflavins of the Cannabis Plant.

Background: Throughout history, Cannabis has had a significant influence on human life as one of the earliest plants cultivated by humans. The plant was a source of fibers used by the oldest known civilizations. Cannabis was also used medicinally in China, India, and ancient Egypt. Delta-9-tetrahydrocannabinol (Δ9-THC), the main psychoactive compound in the plant was identified in 1964 followed by more than 125 cannabinoids. More than 30 flavonoids were isolated from the plant including the characteristic flavonoids called cannflavins, which are prenylated or geranylated flavones. Material and Methods: In this review, the methods of extraction, isolation, identification, biosynthesis, chemical synthesis, analysis and pharmacological activity of these flavonoids are described. Results: The biosynthetic routes of the cannflavins from phenylalanine and malonyl CoA as well as the microbial biotransformation are also discussed. Details of the chemical synthesis are illustrated as an alternative to the isolation from the plant materials along with other possible sources of obtaining cannflavins. Detailed methods discussing the analysis of flavonoids in cannabis are presented, including the techniques used for separation and detection. Finally, the various biological activities of cannflavins are reviewed along with the available molecular docking studies. Conclusion: Despite the low level of cannflavins in cannabis hamper their development as naturally derived products, efforts need to be put in place to develop high yield synthetic or biosynthetic protocols for their production in order for their development as pharmaceutical products.

Inhibition of OAT1/3 and CMPF uptake attenuates myocardial ischemia-induced chronic heart failure via decreasing fatty acid oxidation and the therapeutic effects of ruscogenin

Chronic heart failure (CHF) as a long-term disease is highly prevalent in elder people worldwide. Early diagnosis and treatments are crucial for preventing the development of CHF. Herein, we aimed to identify novel diagnostic biomarker, therapeutic target and drug for CHF. Untargeted metabolomic analysis has been used to characterize the different metabolomic profile between CHF patients and healthy people. Meanwhile, the targeted metabolomic study demonstrated the elevation of 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF) in the serum of CHF patients and coronary artery ligation-induced CHF mice. Subsequently, we firstly observed that elevation of CMPF impaired cardiac function and aggravated myocardial injury by enhancing fatty acid oxidation (FAO). Interestingly, inhibition of responsible transporters organic anion transporter 1/3 (OAT1/3) has been found to decrease the CMPF level, and suppress FAO-related key protein expressions including peroxisome proliferator-activated receptor alpha, peroxisome proliferative activated receptor-α, carnitine palmitoyl transferase 1, and malonyl CoA decarboxylase in coronary artery ligation-induced CHF mice. Meanwhile, the inhibitor of OAT1/3 presented an excellent improvement in cardiac function and histological injury. Based on the above findings, molecular docking was adopted to screen the potential therapeutic drug targeting OAT1/3, and ruscogenin (RUS) exhibited a great binding affinity with OAT1 and OAT3. Next, it was verified that RUS could remarkedly decrease the expression of OAT1/3 and CMPF levels in heart tissue of CHF mice, as well as suppress the expression of FAO-related proteins. What's more, RUS can effectively improve cardiac function, myocardial fibrosis and morphological damage. Collectively, this study provided a potential metabolic marker CMPF and novel target OAT1/3 for CHF, which were demonstrated to be involved in FAO. And RUS was identified as a potential anti-FAO drug for CHF by regulating OAT1/3.

Insoluble Dietary Fiber from Soybean Residue (Okara) Exerts Anti-Obesity Effects by Promoting Hepatic Mitochondrial Fatty Acid Oxidation.

Numerous investigations have shown that insoluble dietary fiber (IDF) has a potentially positive effect on obesity due to a high-fat diet (HFD). Our previous findings based on proteomic data revealed that high-purity IDF from soybean residue (okara) (HPSIDF) prevented obesity by regulating hepatic fatty acid synthesis and degradation pathways, while its intervention mechanism is uncharted. Consequently, the goal of this work is to find out the potential regulatory mechanisms of HPSIDF on hepatic fatty acid oxidation by determining changes in fatty acid oxidation-related enzymes in mitochondria and peroxisomes, the production of oxidation intermediates and final products, the composition and content of fatty acids, and the expression levels of fatty acid oxidation-related proteins in mice fed with HFD. We found that supplementation with HPSIDF significantly ameliorated body weight gain, fat accumulation, dyslipidemia, and hepatic steatosis caused by HFD. Importantly, HPSIDF intervention promotes medium- and long-chain fatty acid oxidation in hepatic mitochondria by improving the contents of acyl-coenzyme A oxidase 1 (ACOX1), malonyl coenzyme A (Malonyl CoA), acetyl coenzyme A synthase (ACS), acetyl coenzyme A carboxylase (ACC), and carnitine palmitoyl transferase-1 (CPT-1). Moreover, HPSIDF effectively regulated the expression levels of proteins involved with hepatic fatty acid β-oxidation. Our study indicated that HPSIDF treatment prevents obesity by promoting hepatic mitochondrial fatty acid oxidation.

Fetal hyperglycemia and the origin of adult obesity

Fetal Hyperglycemia (FH) plays a critical role in adult obesity. FH occurs upon fetal exposure to high maternal glucose during Gestational Diabetes, resulting in hyperinsulinemia and increased fetal fat deposition. At birth, these infants are larger than normal babies, hypoglycemic and hyperinsulinemic and have a higher risk of adult-onset metabolic disorders such as obesity, Type 2 Diabetes and non-alcoholic fatty liver disease (NAFLD). Although in utero glucose exposure provides evidence in the above-mentioned conditions the molecular mechanisms remain unclear. Using a Zebrafish model of FH, we aim to test the hypothesis that FH increases hepatic de novo lipogenesis causing obesity later in life. Methods: We developed a novel Zebrafish model of FH by exposing embryos to high glucose (4.5% w/v) at day 4 post fertilization (4 dpf) during the last day of embryogenesis. At 5 dpf the glucose media was replaced by regular media with or without the Acetyl-CoA Carboxylase (acca) inhibitor ND646 for additional 24 hrs followed by embryo collection. Adult fish were raised from glucose-exposed embryos on a normal diet. Fat mass was assessed by Echo-MRI and glucose levels by glucometer. The substrate of de novo lipogenesis, malonyl CoA level was quantified by ELISA and triglycerides by colorimetry. Insulin expression (visualized by whole mount in-situ hybridization), lipogenic (acca), beta oxidation [(Carnitine palmitoyltransferase, (cpt1/2)] and gluconeogenic [(Glucagon (gcga), Glucose-6-Phosphatase (G6Pase), Phosphoenolpyruvate carboxykinase (pck1)] markers were quantified by RT-qPCR. Oil-Red-O staining (ORO) was used to detect lipid accumulation and quantified using spectrophotometry, while Nile red staining was used to detect adipocyte accumulation. Results: Zebrafish embryos become transiently hyperglycemic and hyperinsulinemic after 24 hrs of glucose exposure at 5 dpf. Surprisingly, despite being normoglycemic glucose-exposed embryos at 6 dpf showed significantly higher levels of hepatic lipid accumulation (48%) and de novo lipogenesis (acca and malonyl CoA) as well as markers of gluconeogenesis (gcga, G6Pase, pck1) and beta oxidation (cpt1/2), compared to controls. Interestingly, adult fish (3 months) become obese (fat mass, 2.5±0.2 vs 3.7±0.2) and develop epicardial fat deposition, despite being normoglycemic. At the molecular level, adult fish have increased fasting hepatic de novo lipogenesis, as indicated by elevated acca expression and malonyl CoA levels which was associated with higher hepatic triglyceride levels (1.5-fold) compared to adult fish raised from unexposed embryos. ND 646 administration reduced lipid accumulation in embryos. The effect of ND 646 on adult fish is under evaluation. Conclusion: Together our results show that FH induces persistent increase in whole embryonic and adult hepatic de novo lipogenesis and its pharmacological inhibition could be promising therapeutic intervention to rescue FH-induced adulthood obesity. National Institute of Health grant (P20 GM104357) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The Protective Effect of 11-Keto-β-Boswellic Acid against Diabetic Cardiomyopathy in Rats Entails Activation of AMPK

This study examined the protective effect of 11-keto-β-boswellic acid (AKBA) against streptozotocin (STZ)-induced diabetic cardiomyopathy (DC) in rats and examined the possible mechanisms of action. Male rats were divided into 5 groups (n = 8/each): (1) control, AKBA (10 mg/kg, orally), STZ (65 mg/kg, i.p.), STZ + AKBA (10 mg/kg, orally), and STZ + AKBA + compound C (CC/an AMPK inhibitor, 0.2 mg/kg, i.p.). AKBA improved the structure and the systolic and diastolic functions of the left ventricles (LVs) of STZ rats. It also attenuated the increase in plasma glucose, plasma insulin, and serum and hepatic levels of triglycerides (TGs), cholesterol (CHOL), and free fatty acids (FFAs) in these diabetic rats. AKBA stimulated the ventricular activities of phosphofructokinase (PFK), pyruvate dehydrogenase (PDH), and acetyl CoA carboxylase (ACC); increased levels of malonyl CoA; and reduced levels of carnitine palmitoyltransferase I (CPT1), indicating improvement in glucose and FA oxidation. It also reduced levels of malondialdehyde (MDA); increased mitochondria efficiency and ATP production; stimulated mRNA, total, and nuclear levels of Nrf2; increased levels of glutathione (GSH), heme oxygenase (HO-1), superoxide dismutase (SOD), and catalase (CAT); but reduced the expression and nuclear translocation of NF-κB and levels of tumor-necrosis factor-α (TNF-α) and interleukin-6 (IL-6). These effects were concomitant with increased activities of AMPK in the LVs of the control and STZ-diabetic rats. Treatment with CC abolished all these protective effects of AKBA. In conclusion, AKBA protects against DC in rats, mainly by activating the AMPK-dependent control of insulin release, cardiac metabolism, and antioxidant and anti-inflammatory effects.

HPLC-MS-based untargeted metabolomic analysis of differential plasma metabolites and their associated metabolic pathways in reproductively anosmic black porgy, Acanthopagrus schlegelii

Olfaction, a universal form of chemical communication, is a powerful channel for animals to obtain social and environmental cues. The mechanisms by which fish olfaction affects reproduction, breeding and disease control are not yet clear. To evaluate metabolites profiles, plasma from anosmic and control black porgy during reproduction was analyzed by non-targeted metabolomics using ultra high-performance liquid chromatography–mass spectrometry and multivariate statistical analysis techniques, including principal component analysis and orthogonal partial least squares discriminant analysis. The metabolite profiles of anosmia and control groups were found to be significantly separated. Ten different differential metabolites, mainly including amino acids, such as isoleucine and methionine, and lipids, such as phosphatidylserine, were screened based on the combined analysis of variable importance in the projection and p values. In addition, six key differential metabolic pathways were analyzed using the Kyoto Encyclopedia of Genes and Genomes and enriched for four metabolic pathways including the citrate acid (TCA) cycle, tyrosine metabolism, arginine and proline metabolism, and arginine synthesis. The TCA cycle enhances fertility through the reduction of pyruvate kinase, and intermediate derivatives (acetyl CoA, malonyl CoA) act as signaling factors that regulate immune cell function. The tyrosine cycle can indirectly participate and promote reproduction in black porgy through melanin-concentrating hormone. Arginine and proline metabolism can promote reproduction by promoting growth hormone and enhance immunity in anosmic black porgy by stimulating T lymphocytes. Our metabolomic study revealed that anosmia in black porgy played an active role in immunity and reproduction and provided theoretical support for breeding and disease control.

Isolation and Identification of Novel Antioxidant Polyketides from an Endophytic Fungus Ophiobolus cirsii LZU-1509

Sixteen new polyketides, ophicirsins A-P (1-16), including four novel carbon skeletons (5-9, 14, 15, and 16), were isolated from the extract of an endophytic fungus Ophiobolus cirsii LZU-1509. The unique frameworks of ophicirsin N (14) and O (15) feature a different cyclic ether connected with an aromatic ring system. Ophicirsin P (16) is characterized by the unprecedented heterozygote of a polyketide and an alkaloid. The absolute stereochemistries of those polyketides were characterized via single-crystal X-ray diffraction analysis and the experimental and computational electric circular dichroism spectra comparison. Theoretical reaction pathways in the fermentation to generate different novel skeletons starting from acetyl CoA and malonyl CoA helped to assign their structures. Compounds 1-16 appear almost nontoxic in HepG2 and HT-1080 tumor cells. Their antioxidant effects were further evaluated, and 15 exhibits an excellent protection activity in hydrogen peroxide-stimulated oxidative damage in neuron-like PC12 cells via screening all compounds. Moreover, 15 displays a greater ability to scavenge the 2,2-diphenyl-1-picrylhydrazyl free radicals than resveratrol. Taken together, these findings suggest that the novel polyketides could serve as potential antioxidant agents for neuroprotection.

Cholecalciferol affects cardiac proteins regulating malonyl-CoA availability and intracellular calcium level.

Cholecalciferol improves insulin signaling and glucose metabolism in the heart and reduces circulating non-esterified fatty acids. Cholecalciferol effects on the cardiac fatty acid (FA) metabolism and the consequences on calcium handling were examined. Blood lipid profile was determined. Western blot and qRT-PCR were used to examine protein and mRNA expression. Cholecalciferoltreated rats had increased acetyl CoA carboxylase 2 protein expression and decreased expression of malonyl CoA decarboxylase. In addition, the expression of uncoupling protein 3 was elevated. Also, the level of peroxisome proliferator-activated receptor-gamma coactivator in the nucleus of heart cells was increased along with the level of sarcoplasmic/endoplasmic reticulum Ca2+ATPase in the microsomal fraction. In parallel, the L-type calcium channel and ryanodine receptor expression was reduced. In the heart of healthy rats, cholecalciferol affects proteins regulating malonyl CoA availability and intracellular Ca2+ handling proteins.

Engineering the Phenylpropanoid Pathway in Rhodosporidium toruloides for Naringenin Production from Tyrosine by Leveraging on its Native PAL Gene

Flavonoids are valued for their beneficial properties. This was a proof-of-concept study to show that the PAL gene in Rhodosporidium toruloides (R. toruloides) could be harnessed and only two genes 4CL and CHS needed to be inserted to create the naringenin producing strain, CBS-N. The growth of CBS-N reached a higher OD600 86.1 compared to 31.8 by wildtype. High-performance liquid chromatography (HPLC) and liquid chromatography–mass spectrometry (LC–MS) confirmed CBS-N successfully produced 0.038 mg/L naringenin and 16.9 mg/L p-coumaric acid via its PAL/TAL activity when supplemented with tyrosine, although the conversion efficiency of 4CL and CHS genes was the limiting factor. Metabolic profiling by gas chromatography–mass spectrometry (GC–MS) showed that, in the CBS-N strain, metabolic flux was toward glycolysis and the TCA cycle to produce malonyl CoA, the precursor for naringenin synthesis, and away from fatty acids synthesis pathway. Our study showed that microorganisms containing a native PAL gene, such as R. toruloides, could be harnessed for flavonoids production via precision fermentation.

Roles of Ghrelin and Leptin in Body Mass Regulation under Food Restriction Based on the AMPK Pathway in the Red-Backed Vole, Eothenomys miletus, from Kunming and Dali Regions.

The phenotype plasticity of animals' physiological characteristics is an important survival strategy to cope with environmental changes, especially the change in climate factors. Small mammals that inhabit seasonally changing environments often face the stress of food shortage in winter. This study measured and compared the thermogenic characteristics and related physiological indicators in the adenosine-5'-monophosphate-activated protein kinase (AMPK) pathway in Eothenomys miletus between Kunming (KM, n = 18) and Dali (DL, n = 18) under food restriction and refeeding. The results showed that food restriction and the region have significant effects on body mass, the resting metabolic rate (RMR), hypothalamic neuropeptide gene expression, ghrelin levels in the stomach and serum, serum leptin level and the activity of AMPK, and malonyl CoA and carnitine palmitoyltransferase 1 (CPT-1) activity. Food restriction reduced the body mass, the gene expression of neuropeptide proopiomelanocortin (POMC), cocaine- and amphetamine-regulated transcription peptide (CART), and leptin level. However, the ghrelin concentration and AMPK activity increased. After refeeding, there was no difference in these physiological indexes between the food restriction and control groups. Moreover, the physiological indicators also showed regional differences, such as the body mass, POMC and CART gene expression, ghrelin concentration in the stomach and serum, and AMPK activity in DL changed more significantly. All these results showed that food restriction reduces energy metabolism in E. miletus. After refeeding, most of the relevant physiological indicators can return to the control level, indicating that E. miletus has strong phenotypic plasticity. Ghrelin, leptin, and the AMPK pathway play an important role in the energy metabolism of E. miletus under food restriction. Moreover, regional differences in physiological indicators under food restriction may be related to the different temperatures or food resources in different regions.

OR24-5 Zebrafish in Utero Glucose Exposure Induces Lipid Dysregulation That Is Abrogated by Acetyl CoA Carboxylase or Glycolysis Inhibition

Abstract Background and Aim One in ten pregnancies suffer from Gestational Diabetes Mellitus (GDM). GDM exposes fetus to high uterine glucose that causes fetal hyperglycemia. At birth Fetal hyperglycemia results in hypoglycemia, macrosomia, and larger than normal infants and these infants are predisposed to a number of metabolic disorders such as obesity, Type 2 Diabetes and non-alcoholic fatty liver disease (NAFLD) in adulthood. Although in-utero glucose exposure provides evidence for fetal lipid dysregulation linked to metabolic disorders in adults, the molecular mechanisms are still unclear. Increase in circulating insulin and glucose are implicated in the enhanced activation of hepatic De novo lipogenesis (DNL) in dyslipidemia, hence, we aim to investigate the potential beneficial effect of the pharmacological inhibition of DNL or glycolysis in our well-characterized zebrafish model of fetal hyperglycemia that mimics the metabolic disorders in human GDM against lipid derangement mediated by excess glucose in embryos in a short term and avoid the long-term outcome of obesity. Methods We developed a zebrafish model of fetal hyperglycemia by exposing embryos to high glucose (4.5% w/v) during the last day of embryogenesis from 96 to 120 hours post-fertilization (hpf). Glucose level was detected in embryo homogenates by glucometer. Insulin expression was visualized by whole-mount in-situ Hybridization. Gene expression of glycolytic (Hexokinase) and lipogenic [Acetyl-CoA Carboxylase (acca)] markers by RT-qPCR and malonyl CoA levels (product of DNL) by ELISA were also assessed. Lipid accumulation was detected by Oil-Red-O staining (ORO) and quantified by spectrophotometry. Pharmacological intervention using metformin or ND646 (known inhibitors of acca) or 2-Deoxyglucose, 2DG (Known inhibitor of Hexokinase) with glucose for 24hours were utilized to attenuate fetal hyperglycemia-mediated lipid accumulation in embryos. Results Zebrafish embryos exposed to high glucose for 24 hours are transiently hyperglycemic while normoglycemia is restored 24 hours after removal from glucose media. At 120 hpf embryos exposed to high-glucose demonstrated increased insulin, hexokinase, and acca expression compared to untreated controls. We also observed a significant reduction in malonyl CoA levels in ND 646 and metformin cotreated embryos with glucose compared to controls. Interestingly, quantification of ORO staining revealed a significant increase in lipid deposition in glucose treated embryos compared to controls at 120 hpf (0.2±0.01 vrs 0.13±0.005), which was significantly attenuated in embryos co-treated with glucose and 2-DG- (0.15±0.003) or metformin- (0.11±0.007) compared to glucose-treated embryos. Similarly, a moderate reduction in ORO staining was observed in embryos that were co-treated with glucose and ND646 (0.17 ± 0.006). Conclusion and significance Together our results show that embryonic glucose exposure leads to increased lipid accumulation which can be rescued by blocking glycolysis or de novo lipogenesis. Intervening glycolysis and de novo lipogenesis could be a promising therapeutic approach for modulating fetal hyperglycemia-related lipid dysregulations. Presentation: Monday, June 13, 2022 12:00 p.m. - 12:15 p.m.

Effects of the potassium application rate on lipid synthesis and eating quality of two rice cultivars

Lipid content has an important effect on rice eating quality, but the effects of fertilizer application rate on the lipid synthesis and eating quality of rice are not well understood. Potassium (K) has a strong influence on rice quality and the requirement for K fertilizer in rice is greater than for nitrogen (N) and phosphorus (P) fertilizers. To investigate the effects of K fertilizer on the lipid synthesis and eating quality of rice, we used Nanjing 9108 (NJ9108, japonica) and IR72 (indica) rice as experimental materials and four K levels: K0 (0 kg ha–1), K1 (90 kg ha–1), K2 (135 kg ha–1) and K3 (180 kg ha–1). The results showed that the lipid content, free fatty acid (FFA) content, unsaturated fatty acid (UFA) content, malonyl-CoA (MCA) content, phosphatidic acid (PA) content, lipid synthesis-related enzyme activities and eating quality first increased and then decreased with increasing K in both cultivars. The maximum values were obtained under K2. However, the saturated fatty acid (SFA) content showed the opposite trend. No significant differences were found in pyruvate (PYR) content among the K treatments. The protein and oxaloacetic acid (OAA) contents and phosphoenolpyruvate carboxylase (PEPCase) activity of NJ9108 first decreased and then increased with increasing K, and the minimum values were obtained under K2; while IR72 showed the opposite trend and the maximum values were obtained under K1. Overall, increasing K optimized the fatty acid components and increased the lipid content and eating quality of rice by enhancing lipid synthesis-related enzyme activities and regulating substrate competition for lipid and protein synthesis. The optimal K application rate for lipid synthesis, eating quality and grain yield was 135 kg ha–1 for both cultivars.

Paradoxical activation of transcription factor SREBP1c and de novo lipogenesis by hepatocyte-selective ATP-citrate lyase depletion in obese mice

Hepatic steatosis associated with high-fat diet, obesity, and type 2 diabetes is thought to be the major driver of severe liver inflammation, fibrosis, and cirrhosis. Cytosolic acetyl CoA (AcCoA), a central metabolite and substrate for de novo lipogenesis (DNL), is produced from citrate by ATP-citrate lyase (ACLY) and from acetate through AcCoA synthase short chain family member 2 (ACSS2). However, the relative contributions of these two enzymes to hepatic AcCoA pools and DNL rates in response to high-fat feeding are unknown. We report here that hepatocyte-selective depletion of either ACSS2 or ACLY caused similar 50% decreases in liver AcCoA levels in obese mice, showing that both pathways contribute to the generation of this DNL substrate. Unexpectedly however, the hepatocyte ACLY depletion in obese mice paradoxically increased total DNL flux measured by D2O incorporation into palmitate, whereas in contrast, ACSS2 depletion had no effect. The increase in liver DNL upon ACLY depletion was associated with increased expression of nuclear sterol regulatory element–binding protein 1c and of its target DNL enzymes. This upregulated DNL enzyme expression explains the increased rate of palmitate synthesis in ACLY-depleted livers. Furthermore, this increased flux through DNL may also contribute to the observed depletion of AcCoA levels because of its increased conversion to malonyl CoA and palmitate. Together, these data indicate that in fat diet–fed obese mice, hepatic DNL is not limited by its immediate substrates AcCoA or malonyl CoA but rather by activities of DNL enzymes.

Effects of Phosphorus Application Rate on Lipid Synthesis and Eating Quality of Two Rice Grains

Lipids are an important nutritional component of rice, and lipid content has an important effect on rice eating quality. However, the effects of the fertilizer application rate on lipid synthesis and eating quality of rice are poorly understood. To investigate the effects of phosphorus (P) fertilizer on lipid synthesis and eating quality of rice, we used Nanjing (NJ) 9108 (japonica) and IR72 (indica) rice as experimental materials, and four P levels, P0 (0 kg ha−1), P1 (45 kg ha−1), P2 (67.5 kg ha−1) and P3 (135 kg ha−1). The results showed that the lipid, free fatty acid (FFA) content, unsaturated fatty acid (UFA) content, malonyl-CoA (MCA) content, phosphatidic acid (PA) content, lipid synthesis-related enzyme activities and eating quality of both cultivars increased with increasing P. However, the saturated fatty acid (SFA) content showed the opposite trend. No significant differences were found in pyruvate (PYR) content between P treatments. Protein and oxaloacetic acid (OAA) contents and phosphoenolpyruvate carboxylase (PEPCase) activity first increased and then decreased with increasing P, which indicated that high P levels could stimulate lipid synthesis more than protein synthesis. Overall, increasing P optimized fatty acid components and increased the lipid content and eating quality of rice by enhancing lipid synthesis-related enzyme activities and regulating substrate competition for lipid and protein synthesis. The optimal P application rate for lipid synthesis and eating quality of both cultivars was 135 kg ha−1.

Added Fructose in Non-Alcoholic Fatty Liver Disease and in Metabolic Syndrome: A Narrative Review.

Non-alcoholic fatty liver disease (NAFLD) represents the most common chronic liver disease and it is considered the hepatic manifestation of metabolic syndrome (MetS). Diet represents the key element in NAFLD and MetS treatment, but some nutrients could play a role in their pathophysiology. Among these, fructose added to foods via high fructose corn syrup (HFCS) and sucrose might participate in NAFLD and MetS onset and progression. Fructose induces de novo lipogenesis (DNL), endoplasmic reticulum stress and liver inflammation, promoting insulin resistance and dyslipidemia. Fructose also reduces fatty acids oxidation through the overproduction of malonyl CoA, favoring steatosis. Furthermore, recent studies suggest changes in intestinal permeability associated with fructose consumption that contribute to the risk of NAFLD and MetS. Finally, alterations in the hunger–satiety mechanism and in the synthesis of uric acid link the fructose intake to weight gain and hypertension, respectively. However, further studies are needed to better evaluate the causal relationship between fructose and metabolic diseases and to develop new therapeutic and preventive strategies against NAFLD and MetS.

Ca2+/calmodulin-dependent protein kinase II inhibition reduces myocardial fatty acid uptake and oxidation after myocardial infarction

An AMP-activated kinase (AMPK) signaling pathway is activated during myocardial ischemia and promotes cardiac fatty acid (FA) uptake and oxidation. Similarly, the multifunctional Ca2+/calmodulin-dependent protein kinase II (CaMKII) is also triggered by myocardial ischemia, but its function in FA metabolism remains unclear. Here, we explored the role of CaMKII in FA metabolism during myocardial ischemia by investigating the effects of cardiac CaMKII on AMPK-acetyl-CoA carboxylase (ACC), malonyl CoA decarboxylase (MCD), and FA translocase cluster of differentiation 36 (FAT/CD36), as well as cardiac FA uptake and oxidation. Moreover, we tested whether CaMKII and AMPK are binding partners. We demonstrated that diseased hearts from patients with terminal ischemic heart disease displayed increased phosphorylation of CaMKII, AMPK, and ACC and increased expression of MCD and FAT/CD36. AC3-I mice, which have a genetic myocardial inhibition of CaMKII, had reduced gene expression of cardiac AMPK. In post-MI (myocardial infarction) AC3-I hearts, AMPK-ACC phosphorylation, MCD and FAT/CD36 levels, cardiac FA uptake, and FA oxidation were significantly decreased. Notably, we demonstrated that CaMKII interacted with AMPK α1 and α2 subunits in the heart. Additionally, AC3-I mice displayed significantly less cardiac hypertrophy and apoptosis 2 weeks post-MI. Overall, these findings reveal a unique role for CaMKII inhibition in repressing FA metabolism by interacting with AMPK signaling pathways, which may represent a novel mechanism in ischemic heart disease.