The dynamic regulatory network of phosphatidic acid metabolism: a spotlight on substrate cycling between phosphatidic acid and diacylglycerol.

Mammalian cells utilize over 1000 different lipid species to maintain cell and organelle membrane properties, control cell signaling and processes, and store energy. Lipid synthesis and metabolism are mediated by highly interconnected and spatiotemporally regulated networks of lipid-metabolizing enzymes and supported by vesicle trafficking and lipid-transfer at membrane contact sites. However, the regulatory mechanisms that achieve lipid homeostasis are largely unknown. Phosphatidic acid (PA) serves as the central hub for phospholipid biosynthesis, acting as a key intermediate in both the Kennedy pathway and the CDP-DAG pathway. Additionally, PA is a potent signaling molecule involved in various cellular processes. This dual role of PA, both as a critical intermediate in lipid biosynthesis and as a significant signaling molecule, suggests that it is tightly regulated within cells. This minireview will summarize the functional diversity of PA molecules based on their acyl tail structures and subcellular localization, highlighting recent tools and findings that shed light on how the physical, chemical, and spatial properties of PA species contribute to their differential metabolic fates and functions. Dysfunctional effects of altered PA metabolism as well as the strategies cells employ to maintain PA regulation and homeostasis will also be discussed. Furthermore, this review will explore the differential regulation of PA metabolism across distinct subcellular membranes. Our recent proximity labeling studies highlight the possibility that substrate cycling between PA and DAG may be location-dependent and have functional significance in cell signaling and lipid homeostasis.

The therapeutic effect of 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol on chemically induced atopic dermatitis.

Atopic dermatitis (AD) is the most common chronic inflammatory skin disease worldwide. However, it is still urgent to develop innovative treatments that can effectively manage refractory patients with unpredictable chronic disease courses. In this study, we evaluated the therapeutic efficacy of 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG) as a novel agent for AD treatment using a human-like mouse model of AD. PLAG significantly improved 2,4-dinitrochlorobenzene (DNCB)-induced AD skin lesions compared to those in mice treated with DNCB alone. PLAG substantially modulated the AD-induced infiltration of monocytes and eosinophils into skin lesions and humoral systemic responses involving immunoglobulin E (IgE), interleukin (IL)-4, and IL-13, restoring them to a normal state. Next, we compared the therapeutic efficacy of PLAG and abrocitinib for severe AD treatment. PLAG exhibited a significant therapeutic effect on AD skin lesions compared to abrocitinib. Unlike abrocitinib, PLAG significantly reduced AD-induced eosinophil infiltration to a level similar to that observed in untreated negative controls. Notably, both PLAG and abrocitinib downregulated IgE, IL-4, and IL-13 in a similar pattern, reaching levels similar to those in the untreated negative controls. Our findings strongly suggest that PLAG may serve as a therapeutic agent for AD with an efficacy comparable to that of abrocitinib.

Immobilization of Lipase from Thermomyces Lanuginosus and Its Glycerolysis Ability in Diacylglycerol Preparation.

In the glycerolysis process for diacylglycerol (DAG) preparation, free lipases suffer from poor stability and the inability to be reused. To address this, a cost-effective immobilized lipase preparation was developed by cross-linking macroporous resin with poly (ethylene glycol) diglycidyl ether (PEGDGE) followed by lipase adsorption. The selected immobilization conditions were identified as pH 7.0, 35 °C, cross-linking agent concentration 2.0%, cross-linking time 4 h, lipase amount 5 mg/g of support, and adsorption time 4 h. Enzymatic properties of the immobilized lipase were analyzed, revealing enhanced pH stability, thermal stability, storage stability, and operational stability post-immobilization. The conditions for immobilized enzyme-catalyzed glycerolysis to produce DAG were selected, demonstrating the broad applicability of the immobilized lipase. The immobilized lipase catalyzed glycerolysis reactions using various oils as substrates, with DAG content in the products ranging between 35 and 45%, demonstrating broad applicability. Additionally, the changes during the repeated use of the immobilized lipase were characterized, showing that mechanical damage, lipase leakage, and alterations in the secondary structure of the lipase protein contributed to the decline in catalytic activity over time. These findings provide valuable insights for the industrial application of lipase.

Ceramide synthesis inhibitors prevent lipid-induced insulin resistance through the DAG-PKCε-insulin receptorT1150 phosphorylation pathway.

Inhibition of the ceramide synthetic pathway with myriocin or an antisense oligonucleotide (ASO) targeting dihydroceramide desaturase (DES1) both improved hepatic insulin sensitivity in rats fed either a saturated or unsaturated fat diet and was associated with reductions in both hepatic ceramide and plasma membrane (PM)-sn-1,2-diacylglycerol (DAG) content. The insulin sensitizing effects of myriocin and Des1 ASO were abrogated by acute treatment with an ASO against DGAT2, which increased hepatic PM-sn-1,2-DAG but not hepatic C16 ceramide content. Increased PM-sn-1,2-DAG content was associated with protein kinase C (PKC)ε activation, increased insulin receptor (INSR)T1150 phosphorylation leading to reduced insulin-stimulated INSRY1152/AktS473 phosphorylation, and impaired insulin-mediated suppression of endogenous glucose production. These results demonstrate that inhibition of de novo ceramide synthesis by either myriocin treatment or DES1 knockdown protects against lipid-induced hepatic insulin resistance through a C16 ceramide-independent mechanism and that they mediate their effects to protect from lipid-induced hepatic insulin resistance via the PM-sn-1,2-DAG-PKCε-INSRT1150 phosphorylation pathway.

Changes in stability, phytonutrients, 3-chloropropanol esters and glycidyl esters of peanut oil-based diacylglycerols during heat treatment.

Diacylglycerol (DAG) is generally considered one of the precursors of 3-chloropropanol esters (3-MCPDE) and glycidyl esters (GEs). This study aimed to evaluate static heating and stir-frying properties of peanut oil (PO) and PO based 58% and 82% DAG oils (PDAG-58 and PDAG-82). Observations revealed that, phytonutrient levels notably diminished during static heating, with PDAG exhibiting reduced oxidative stability, but maintaining a stability profile similar to PO over a short period. During stir-frying, 3-MCPDE content initially increased and then decreased whereas the opposite was observed for GEs. Furthermore, as temperature, and NaCl concentration increased, there was a corresponding increase in the levels of 3-MCPDE and GEs, although remained within safe limits. When used in suitable concentrations, these findings underscore the potential of DAG, as a nutritionally rich and oxidatively stable alternative to conventional cooking oils, promoting the use of DAG edible oil in heat-cooked food systems.

Pulmonary Administration of TLR2/6 Agonist after Allergic Sensitization Inhibits Airway Hyper-Responsiveness and Recruits Natural Killer Cells in Lung Parenchyma.

Asthma is a chronic lung disease with persistent airway inflammation, bronchial hyper-reactivity, mucus overproduction, and airway remodeling. Antagonizing T2 responses by triggering the immune system with microbial components such as Toll-like receptors (TLRs) has been suggested as a therapeutic concept for allergic asthma. The aim of this study was to evaluate the effect of a TLR2/6 agonist, FSL-1 (Pam2CGDPKHPKSF), administered by intranasal instillation after an allergic airway reaction was established in the ovalbumin (OVA) mouse model and to analyze the role of natural killer (NK) cells in this effect. We showed that FSL-1 decreased established OVA-induced airway hyper-responsiveness and eosinophilic inflammation but did not reduce the T2 or T17 response. FSL-1 increased the recruitment and activation of NK cells in the lung parenchyma and modified the repartition of NK cell subsets in lung compartments. Finally, the transfer or depletion of NK cells did not modify airway hyper-responsiveness and eosinophilia after OVA and/or FSL-1 treatment. Thus, the administration of FSL-1 reduces airway hyper-responsiveness and bronchoalveolar lavage eosinophilia. However, despite modifications of their functions following OVA sensitization, NK cells play no role in OVA-induced asthma and its inhibition by FSL-1. Therefore, the significance of NK cell functions and localization in the airways remains to be unraveled in asthma.

Structure-function relationship of phase-separated liposomes containing diacylglycerol analogues.

The composition and morphology of lipid-based nanoparticles can influence their overall in vivo behavior. Previously, we demonstrated that phase separation in liposomes composed of DSPC and a diacylglycerol lipid analogue (DOaG) drives the in vivo biodistribution towards a specific subset of endothelial cells in zebrafish embryos. In the absence of traditional targeting functionalities (e.g., antibodies, ligands), this selectivity is mediated solely by the unique liposome morphology and composition, characterized by a DOaG-rich lipid droplet within the DSPC-rich phospholipid bilayer. The phase separation is induced due to the geometry of DOaG lipid and its ability to create non-bilayer phases in lipid membranes. To investigate the underlying principles of phase separation and to optimize the liposome colloidal stability, we performed a structure-function relationship study by synthesizing a library of DOaG analogues with varying molecular properties, such as the number, length and sn-position of the acyl chains, as well as the degree of saturation or carbonyl substituents. We assessed the ability of these lipid analogues to assemble into phase-separated liposomes and studied their morphology, colloidal stability, and in vivo biodistribution in zebrafish embryos. We found that analogues containing unsaturated, medium length (C16-C18) fatty acids were required to obtain colloidally stable, phase-separated liposomes with cell-specific biodistribution patterns. Moreover, we observed that using the pure DOaG isomer, with acyl chains at the sn-1,3 positions, leads to more colloidally stable liposomes than when a mixture of sn-1,2 and sn-1,3 isomers is used. Similarly, we observed that incorporating a DOaG analogue with fatty tails shorter than DSPC, as well as PEGylation, endows liposomes with long term stability while retaining cell-selective biodistribution. Diacylglycerols are known to promote fusion, lipid polymorphism, signaling and protein recruitment on lipid membranes. In this study, we showed that diacylglycerol derivatives can induce phase separation in liposomes, unlocking the potential for cell-specific targeting in vivo. We believe that these findings can be the foundation for future use of diacylglycerols in lipid-based nanomedicines and could lead to the development of novel targeted delivery strategies.

The PAH1-encoded phosphatidate phosphatase of Yarrowia lipolytica differentially affects gene expression and lipid biosynthesis.

Yarrowia lipolytica is a model oleaginous yeast with a strong capacity for lipid accumulation, yet its lipid metabolic pathways and regulatory mechanisms remain largely unexplored. The PAH1-encoded phosphatidate (PA) phosphatase governs lipid biosynthesis by its enzymatic activity and regulating the transcription of genes involved in phospholipid biosynthesis. In this work, we examined the effect of the loss of Pah1 (i.e., pah1Δ) on cell metabolism in cells growing in low- and high-glucose media. Multi-omics analyses revealed the global effect of the pah1Δ mutation on lipid and central carbon metabolism. Lipidomics analyses showed that the pah1Δ mutation caused a massive decrease in the masses of triacylglycerol (TAG) and diacylglycerol (DAG), and these effects were independent of glucose concentration in the media. Conversely, phospholipid levels declined in low-glucose media but increased in high-glucose media. The loss of Pah1 affected the expression of genes involved in key pathways of glucose metabolism, such as glycolysis, citric acid cycle, oxidative phosphorylation, and the pentose phosphate pathway, and these effects were more pronounced in high-glucose media. In lipid biosynthesis, the genes catalyzing phosphatidylcholine (PC) synthesis from phosphatidylethanolamine (PE) were upregulated within the CDP-DAG pathway. In contrast, PC synthesis through the Kennedy pathway was downregulated. The ethanolamine branch of the Kennedy pathway that synthesizes PE was also upregulated in pah1Δ. Interestingly, we noted a massive increase in the levels of lysophospholipids, consistent with the upregulation of genes involved in lipid turnover. Overall, this work identified novel regulatory roles of Pah1 in lipid biosynthesis and gene expression.

Pickering Foam Stabilized by Diacylglycerol-Based Solid Lipid Nanoparticles: Effect of Protein Modification.

Pickering foams have great potential for applications in aerated foods, but their foaming ability and physical stability are still far from satisfactory. Herein, solid lipid particles (SLNs) were fabricated by using diacylglycerol of varying acyl chain lengths with modification by a protein. The SLNs showed different crystal polymorphisms and air-water interfacial activity. C14-DAG SLN with a contact angle ∼ 79° formed aqueous foam with supreme stability and high plasticity. Whey protein isolate and sodium caseinate (0.1 wt %) considerably enhanced the foamability and interfacial activity of SLNs and promoted the packing of particles at the bubble surface. However, high protein concentration caused foam destruction due to the competitive adsorption effect. ß-sheet increased in protein after adsorption and changed the polymorphism and thermodynamic properties of SLN. The foam collapsing behaviors varied in the presence of protein. The results gave insights into fabricating ultrastable aqueous foams by using high-melting DAG particles. The obtained foams demonstrated good temperature sensitivity and plasticity, which showed promising application prospects in the food and cosmetic fields.

Effect of diacylglycerol on partial coalescence of aerated emulsions: Fat crystal-membrane interaction and air-liquid Interface interaction insights.

Currently, the poor whipping capabilities of anhydrous milk fat (AMF) in aerated emulsion products are a major obstacle for their use in beverages like tea and coffee, as well as in cakes and desserts, presenting fresh hurdles for the food industry. In this study, the mechanism of action of diacylglycerols (DAGs) with different carbon chain lengths and degrees of saturation on the partial coalescence of aerated emulsions was systematically investigated from three fundamental perspectives: fat crystallization, air-liquid interface rheology, and fat globule interface properties. The optimized crystallization of long carbon chain length diacylglycerol (LCD) based on stearate enhances interactions between fat globules at the air-liquid interface (with an elastic modulus E' reaching 246.42 mN/m), leading to a significantly reduced interface membrane strength. This promotes fat crystal-membrane interactions during whipping, resulting in a thermally stable foam structure with excellent shaping capability due to enhanced partial coalescence of fat globules. Although Laurate based medium carbon chain length diacylglycerol (MCD) promoted fat crystallization and optimized interface properties, it showed weaker foam properties because it did not adequately encapsulate air bubbles during whipping. Conversely, oleate long carbon chain length diacylglycerol (OCD) proved to be ineffective in facilitating fat crystal-membrane interaction, causing foam to have a subpar appearance. Hence, drawing from the carefully examined fat crystal-membrane interaction findings, a proposed mechanism sheds light on how DAGs impact the whipping abilities of aerated emulsions. This mechanism serves as a blueprint for creating aerated emulsions with superior whipping capabilities and foam systems that are resistant to heat.

shRNA-mediated down-regulation of Acsl1 reverses skeletal muscle insulin resistance in obese C57BL6/J mice.

Prolonged consumption of diet rich in fats is regarded as the major factor leading to the insulin resistance (IR) and type 2 diabetes (T2D). Emerging evidence link excessive accumulation of bioactive lipids such as diacylglycerol (DAG) and ceramide (Cer), with impairment of insulin signaling in skeletal muscle. Until recently, little has been known about the involvement of long-chain acyl-CoAs synthetases in the above mechanism. To examine possible role of long-chain acyl-coenzyme A synthetase 1 (Acsl1) (a major muscular ACSL isoform) in mediating HFD-induced IR we locally silenced Acsl1 in gastrocnemius of high-fat diet (HFD)-fed C57BL/6J mice through electroporation-delivered shRNA and compared it to non-silenced tissue within the same animal. Acsl1 down-regulation decreased the content of muscular long-chain acyl-CoA (LCACoA) and both the Cer (C18:1-Cer and C24:1-Cer) and DAG (C16:0/18:0-DAG, C16:0/18:2-DAG, C18:0/18:0-DAG) and simultaneously improved insulin sensitivity and glucose uptake as compared with non-silenced tissue. Acsl1 down-regulation decreased expression of mitochondrial ß-oxidation enzymes, and the content of both the short-chain acylcarnitine (SCA-Car) and short-chain acyl-CoA (SCACoA) in muscle, pointing towards reduction of mitochondrial FA oxidation. The results indicate, that beneficial effects of Acsl1 partial ablation on muscular insulin sensitivity are connected with inhibition of Cer and DAG accumulation, and outweigh detrimental impact of decreased mitochondrial fatty acids metabolism in skeletal muscle of obese HFD-fed mice.

Mitigating the Effects of 1-Palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol on Gastrointestinal Acute Radiation Syndrome after Total-Body Irradiation in Mice.

Total-body irradiation (TBI) with gamma rays can damage organisms in various unexpected ways and trigger several organ dysfunction syndromes, such as acute radiation syndrome (ARS). Hematopoietic cells and enterocytes are particularly sensitive to radiation due to their self-renewal ability and rapid division, which leads to hematopoietic ARS (H-ARS) and gastrointestinal ARS (GI-ARS). We previously showed that a lipid-based small molecule, 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG), improved 30-day survival and alleviated H-ARS symptoms in BALB/c mice after a lethal dose (LD70/30) of gamma-ray TBI. In this study, we investigated the mitigating effects of PLAG on radiation-induced GI damage that occurs under the same conditions as H-ARS in BALB/c mice. Our study showed that PLAG facilitated the structural restoration of intestinal tissues by increasing villus height, crypt depth, crypt number, mucin-producing goblet cells, and proliferating cell nuclear antigen (PCNA)-positive crypt cells. PLAG significantly improved intestinal absorptive capacity and reduced intestinal injury-induced bacterial translocation. In addition, PLAG effectively inhibited radiation-induced necroptosis signaling activation in the intestinal crypt cells, which was responsible for sustained tissue damage and the release of high mobility group box 1 (HMGB1), a typical damage-associated molecular pattern. Overall, our findings support the radiation-mitigating potential of PLAG against GI-ARS after accidental radiation exposure.

1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol treatment inhibits abnormal tumor growth by regulating neutrophil infiltration in a non-small cell lung carcinoma mouse model.

Excessive neutrophil infiltration into the tumor microenvironment (TME) is an important factor that contributes to tumor overgrowth and limited immunotherapy efficacy. Neutrophils activate various receptors involved in tumor progression, while suppressing the infiltration and activity of cytotoxic T cells and creating optimal conditions for tumor growth. Therefore, the appropriate control of neutrophil infiltration is an effective strategy for tumor treatment. In the present study, 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG) inhibited tumor overgrowth by suppressing excessive neutrophil infiltration, resulting in >74.97 % reduction in tumor size in a Lewis lung carcinoma (LLC-1) mouse model. All subjects in the positive control group died during the 90-day survival period, whereas only four subjects in the PLAG treatment group survived. PLAG had a significantly higher tumor growth inhibitory effect and survival rate than other neutrophil infiltration-targeting inhibitors (e.g., Navarixin, lymphocyte antigen 6 complex locus G6D antibody [aLy6G]). The ability of PLAG to regulate neutrophil infiltration and inhibit tumor growth depends on thioredoxin-interacting protein (TXNIP). In tumors lacking TXNIP expression, PLAG failed to control neutrophil infiltration and infiltration-related factor release, and the inhibitory effect of PLAG on tumor growth was reduced. PLAG-mediated inhibition of neutrophil infiltration enhances the efficacy of immune checkpoint inhibitors (ICIs), increasing the antitumor efficacy and survival rate by 30 %. In conclusion, PLAG could be a novel alternative to anti-tumor drugs that effectively targets excessive neutrophil infiltration into cancer tissues.

Lipidomics and metabolomics investigation into the effect of DAG dietary intervention on hyperuricemia in athletes.

The occurrence of hyperuricemia (HUA; elevated serum uric acid) in athletes is relatively high despite that exercise can potentially reduce the risk of developing this condition. Although recent studies have shown the beneficial properties of DAG in improving overall metabolic profiles, a comprehensive understanding of the effect of DAG in modulating HUA in athletes is still lacking. In this study, we leveraged combinatorial lipidomics and metabolomics to investigate the effect of replacing TAG with DAG in the diet of athletes with HUA. A total of 1,074 lipids and metabolites from 94 classes were quantitated in serum from 33 athletes, who were categorized into responders and non-responders based on whether serum uric acid levels returned to healthy levels after the DAG diet intervention. Lipidomics and metabolomics analyses revealed lower levels of xanthine and uric acid in responders, accompanied by elevated plasmalogen phosphatidylcholines and diminished acylcarnitine levels. Our results highlighted the mechanisms behind how the DAG diet circumvented the risk and effects associated with high uric acid via lowered triglycerides at baseline influencing the absorption of DAG resulting in a decline in ROS and uric acid production, increased phospholipid levels associated with reduced p-Cresol metabolism potentially impacting on intestinal excretion of uric acid as well as improved ammonia recycling contributing to decreased serum uric acid levels in responders. These observed alterations might be suggestive that successful implementation of the DAG diet can potentially minimize the likelihood of a potentially vicious cycle occurring in high uric acid, elevated ROS, and impaired mitochondrial metabolism environment.

Key contributions of a glycolipid to membrane protein integration.

Regulation of membrane protein integration involves molecular devices such as Sec-translocons or the insertase YidC. We have identified an integration-promoting factor in the inner membrane of Escherichia coli called membrane protein integrase (MPIase). Structural analysis revealed that, despite its enzyme-like name, MPIase is a glycolipid with a long glycan comprising N-acetyl amino sugars, a pyrophosphate linker, and a diacylglycerol (DAG) anchor. Additionally, we found that DAG, a minor membrane component, blocks spontaneous integration. In this review, we demonstrate how they contribute to Sec-independent membrane protein integration in bacteria using a comprehensive approach including synthetic chemistry and biophysical analyses. DAG blocks unfavorable spontaneous integrations by suppressing mobility in the membrane core, whereas MPIase compensates for this. Moreover, MPIase plays critical roles in capturing a substrate protein to prevent its aggregation, attracting it to the membrane surface, facilitating its insertion into the membrane, and delivering it to other factors. The combination of DAG and MPIase efficiently regulates the integration of membrane proteins.

Influences of ultrasonic treatment on the physicochemical properties and microstructure of diacylglycerol-loaded emulsion stabilized with soybean protein isolate and sodium alginate.

This study examined the impacts of ultrasonic power (0, 150, 300, 450, 600, and 750 W) and ultrasonic durations (3, 6, 9, 12, and 15 min) on the physicochemical properties and microstructure of diacylglycerol (DAG)-loaded emulsions stabilized with soybean protein isolate (SPI) and sodium alginate (SA). The findings indicated that the smallest particle size, zeta potential, and contact angle for SPI-SA-DAG emulsions were respectively 5.58 µm, -49.85 mV, and 48.65°, achieved at an ultrasonic power of 450 W. The emulsification properties, loss modulus, storage modulus, and apparent viscosity of the emulsions were optimal at this power setting and at a duration of 9 min. Analytical techniques, including confocal laser scanning-, scanning electron-, and atomic force microscopy, revealed that ultrasonication significantly altered emulsion aggregation state, with the surface roughness (Rq) being minimized at 450 W. These results demonstrated that the stability of SPI-SA-DAG emulsions can be effectively enhanced by an appropriate ultrasonic treatment at 450 W for 9 min. This research provides theoretical support for the broad application of sonication techniques in the food industry.

A comparative lipid profile of four fish species: From muscle to industrial by-products based on RPLC-Q-TOF-MS/MS.

Fish are crucial for the fishing industry and essential nutrient provision, including lipids. This study employed a high-throughput lipidomic approach to evaluate and contrast the lipid profiles of three marine fish species (P. crocea, S. fuscens, and C. saira) and one freshwater species (H. molitrix) across head, muscle, and viscera. Over 1000 molecular lipid species across 17 subclasses were identified. Notably, acylated monogalactosyldiacylglycerol (acMGDG) was detected for the first time in these species, with a high prevalence of saturated fatty acids (44.7 %-87.7 %). Glycerolipids (67.7 - 86.3 %) and PLs (10.7 - 31.8 %) were identified as the dominant lipid classes. Marine fish muscles displayed higher PL content than freshwater species, and P. crocea viscera contained over 30 % PLs of total lipids. In particular, ether phosphatidyl ethanolamine incorporated more DHA than ether phosphatidylcholine. The viscera of four fish species also exhibited a significant abundance of diacylglycerol (DG), indicating their potential as functional lipid sources. Multivariate analysis identified triglyceride (TG) (59:13), DG (16:1/22:5), and MGDG (16:0/18:2) as potential biomarkers for differentiating among fish anatomical parts. This study deepens the understanding of the nutritional values of these fish, providing guidance for consumer dietary choices and paving the way for transforming previously underutilized by-products into resources with high-value potential.

The Lipid-Metabolism-Associated Anti-Obesity Properties of Rapeseed Diacylglycerol Oil.

To investigate the effects of rapeseed diacylglycerol oil (RDG) intake on lipid accumulation and metabolism in C57BL/6J mice, obese mice were fed a high-fat diet in which 45% of the total energy content came from RDG (RDGM group) or rapeseed triacylglycerol oil (RTGM group). This diet intervention was conducted for 12 weeks following the establishment of the obese mouse model. By the end of the experiment, the serum glucose levels of the mice in the RTGM and RDGM groups were 13.0 ± 1.3 mmol/L and 9.7 ± 1.5 mmol/L, respectively. Meanwhile, the serum triglyceride level in the RDGM group was 26.3% lower than that in the RTGM group. The weight-loss effect in the RDGM group was accompanied by a significant decrease in the white adipose tissue (WAT) index. The RDG intervention did not significantly change the antioxidant and anti-inflammatory properties of the rapeseed oil in vivo. The RDG diet improved the liver lipid metabolism abnormalities induced by a high-fat diet, leading to decreased liver damage index values (AST and ALT). Additionally, compared to that in the RTGM group, the expression of the adipogenic genes PPAR-γ and DGAT decreased in both the liver and intestine by 21.7% and 16.7% and by 38.7% and 47.2%, respectively, in the RDGM group. Further, most lipolytic genes in BAT showed no significant change after the RDG intervention. This implies that RDG regulates lipid metabolism by altering the expression of adipogenic genes in the liver, intestine, and adipose tissue, thereby reducing the accumulation of WAT. Furthermore, the RDG diet enhanced gut flora diversity, increasing the relative levels of unclassified Muribaculaceae and decreasing the levels of Dubosiella and Faecalibaculum in the mouse gut, potentially accelerating lipid metabolism. Thus, a three-month RDG diet intervention in obese mice exhibited benefits in regulating the somatotype, serum obesity-related indices, gut flora structure, and lipid metabolism in the adipose tissue, liver, and intestine.

Diacylglycerol Signaling in Retinal Ganglion Cells.

With impaired retinal ganglion cell (RGC) function and eventual RGC death, there is a heightened risk of experiencing glaucoma-induced blindness or other optic neuropathies. Poor RGC efficiency leads to limited transmission of visual signals between the retina and the brain by RGC axons. Increased focus on studying lipid messengers found in neurons such as endocannabinoids (eCBs) has importance due to their potential axonal pathway regenerative properties. 2-Arachidonoylglycerol (2-AG), a common eCB, is synthesized from an sn-1 hydrolysis reaction between diacylglycerol (DAG) and diacylglycerol lipase (DAGL). Examination of DAG production allows for future downstream analysis in relation to DAGL functionality. Here, we describe protocol guidelines for extracting RGCs from mouse retinas and subsequent mass spectrometry analysis of the DAG content present within the RGCs.

A protocol for measuring the activity of protein kinase C-delta in murine bone-marrow-derived dendritic cells.

Protein kinase C-δ (PKC-δ) is a key enzyme controlling growth, differentiation, and apoptosis in various cells, including immune cells. Here, we present a protocol to determine PKC-δ activation in response to increased membrane-bound diacylglycerol or phorbol-12-myristate-13-acetate treatment in murine bone-marrow-derived dendritic cells. We describe steps for dendritic cell differentiation, the isolation of plasma membrane lipids, and the quantification of diacylglycerol. We then detail procedures for measuring PKC-δ kinase activity by in vitro assay, indirect immunofluorescence, and western blotting experiments. For complete details on the use and execution of this protocol, please refer to Parsons et al.1.