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Applied Microbiology and Biotechnology Sep 2023Mortierella alpina produces various polyunsaturated fatty acids in the form of triacylglycerols (TAG). Diacylglycerol acyltransferase (DGAT) catalyzes the binding of...
Mortierella alpina produces various polyunsaturated fatty acids in the form of triacylglycerols (TAG). Diacylglycerol acyltransferase (DGAT) catalyzes the binding of acyl-CoA to diacylglycerol to form TAG and is the key enzyme involved in TAG synthesis. A variety of DGATs are present in M. alpina; however, comparative analysis of the functional properties and substrate selectivity of these DGATs is insufficient. In this study, DGAT1 (MaDGAT1A/1B/1C) and DGAT2 (MaDGAT2A/2B) isoforms from M. alpina were analyzed and heterologously expressed in S. cerevisiae H1246. The results showed that MaDGAT1A/1B/2A/2B were able to restore TAG synthesis, and the corresponding TAG content in recombinant yeasts was 2.92 ± 0.42%, 3.62 ± 0.22%, 0.86 ± 0.34%, and 0.18 ± 0.09%, respectively. In S. cerevisiae H1246, MaDGAT1A preferred C16:1 among monounsaturated fatty acids, MaDGAT1B preferred C16:0 among saturated fatty acids (SFAs), and MaDGAT2A/2B preferred C18:0 among SFAs. Under exogenous addition of polyunsaturated fatty acids (PUFAs), MaDGAT1A and 2A preferentially assembled linoleic acid into TAG, and MaDGAT2B had substrate selectivity for eicosapentaenoic and linoleic acids in ω-6 PUFAs. In vitro, MaDGAT1A showed no obvious acyl-CoA selectivity and MaDGAT1B preferred C20:5-CoA. MaDGAT1A/1B preferred C18:1/C18:1-DAG compared with C20:4/C20:4-DAG. This study indicates that MaDGATs have the potential to be used in the production of LA/EPA-rich TAG and provide a reference for improving the production of TAGs in oleaginous fungi. KEY POINTS: • MaDGAT1A preferred C16:1 among MUFAs, MaDGAT1B and MaDGAT2A/2B preferred C16:0 and C18:0 among SFAs, respectively • MaDGAT1A/2A preferentially assembled linoleic acid into TAG, and MaDGAT2B has substrate selectivity for eicosapentaenoic acid and linoleic acid in ω-6 PUFAs • MaDGAT1A showed no obvious acyl-CoA selectivity, and MaDGAT1B preferred C20:5-CoA. MaDGAT1A/1B preferred to select C18:1/C18:1-DAG compared with C20:4/C20:4-DAG.
Topics: Diacylglycerol O-Acyltransferase; Saccharomyces cerevisiae; Linoleic Acid; Diglycerides; Fatty Acids; Fatty Acids, Unsaturated; Triglycerides; Acyltransferases
PubMed: 37498333
DOI: 10.1007/s00253-023-12694-y -
Advances in Biological Regulation Jan 2024Cancer still represents the second leading cause of death right after cardiovascular diseases. According to the World Health Organization (WHO), cancer provoked around... (Review)
Review
Cancer still represents the second leading cause of death right after cardiovascular diseases. According to the World Health Organization (WHO), cancer provoked around 10 million deaths in 2020, with lung and colon tumors accounting for the deadliest forms of cancer. As tumor cells become resistant to traditional therapeutic approaches, immunotherapy has emerged as a novel strategy for tumor control. T lymphocytes are key players in immune responses against tumors. Immunosurveillance allows identification, targeting and later killing of cancerous cells. Nevertheless, tumors evolve through different strategies to evade the immune response and spread in a process called metastasis. The ineffectiveness of traditional strategies to control tumor growth and expansion has led to novel approaches considering modulation of T cell activation and effector functions. Program death receptor 1 (PD-1) and cytotoxic T-lymphocyte antigen 4 (CTLA-4) showed promising results in the early 90s and nowadays are still being exploited together with other drugs for several cancer types. Other negative regulators of T cell activation are diacylglycerol kinases (DGKs) a family of enzymes that catalyze the conversion of diacylglycerol (DAG) into phosphatidic acid (PA). In T cells, DGKα and DGKζ limit the PLCγ/Ras/ERK axis thus attenuating DAG mediated signaling and T cell effector functions. Upregulation of either of both isoforms results in impaired Ras activation and anergy induction, whereas germline knockdown mice showed enhanced antitumor properties and more effective immune responses against pathogens. Here we review the mechanisms used by DGKs to ameliorate T cell activation and how inhibition could be used to reinvigorate T cell functions in cancer context. A better knowledge of the molecular mechanisms involved upon T cell activation will help to improve current therapies with DAG promoting agents.
Topics: Animals; Mice; Diacylglycerol Kinase; Diglycerides; T-Lymphocytes; Neoplasms; Immunotherapy
PubMed: 37949728
DOI: 10.1016/j.jbior.2023.100999 -
Drug Resistance Updates : Reviews and... Mar 2024Tumor-associated macrophages (TAMs) are often associated with chemoresistance and resultant poor clinical outcome in solid tumors. Here, we demonstrated that...
Tumor-associated macrophage (TAM)-secreted CCL22 confers cisplatin resistance of esophageal squamous cell carcinoma (ESCC) cells via regulating the activity of diacylglycerol kinase α (DGKα)/NOX4 axis.
Tumor-associated macrophages (TAMs) are often associated with chemoresistance and resultant poor clinical outcome in solid tumors. Here, we demonstrated that TAMs-released chemokine-C-C motif chemokine 22 (CCL22) in esophageal squamous cell carcinoma (ESCC) stroma was tightly correlated with the chemoresistance of ESCC patients. TAMs-secreted CCL22 was able to block the growth inhibitory and apoptosis-promoting effects of cisplatin on ESCC cells. Mechanistically, CCL22 stimulated intratumoral diacylglycerol kinase α (DGKα) to produce phosphatidic acid (PA), which suppressed the activity of NADPH oxidase 4 (NOX4) and then blocked the overproduction of intratumoral reactive species oxygen (ROS) induced by cisplatin. CCL22 activated DGKα/nuclear factor-κB (NF-κB) axis to upregulate the level of several members of ATP binding cassette (ABC) transporter superfamily, including ABC sub-family G member 4 (ABCG4), ABC sub-family A member 3 (ABCA3), and ABC sub-family A member 5 (ABCA5), to lower the intratumoral concentration of cisplatin. Consequently, these processes induced the cisplatin resistance in ESCC cells. In xenografted models, targeting DGKα with 5'-cholesterol-conjugated small-interfering (si) RNA enhanced the chemosensitivity of cisplatin in ESCC treatment, especially in the context of TAMs. Our data establish the correlation between the TAMs-induced intratumoral metabolic product/ROS axis and chemotherapy efficacy in ESCC treatment and reveal relevant molecular mechanisms.
Topics: Humans; Esophageal Squamous Cell Carcinoma; Cisplatin; Esophageal Neoplasms; Diacylglycerol Kinase; Carcinoma, Squamous Cell; Tumor-Associated Macrophages; NADPH Oxidase 4; Reactive Oxygen Species; RNA, Small Interfering; Cell Proliferation; Chemokines; Cell Line, Tumor; Chemokine CCL22
PubMed: 38387281
DOI: 10.1016/j.drup.2024.101055 -
Cell Host & Microbe Mar 2024Phosphatidic acid (PA) and reactive oxygen species (ROS) are cellular messengers that relay signals to regulate diverse biological processes. In recent issues of Cell...
Phosphatidic acid (PA) and reactive oxygen species (ROS) are cellular messengers that relay signals to regulate diverse biological processes. In recent issues of Cell Host & Microbe and Cell, Qi et al. and Kong et al., respectively, investigate diacylglycerol kinase 5-mediated PA in regulating ROS signaling and plant immunity.
Topics: Reactive Oxygen Species; Signal Transduction; Diacylglycerol Kinase; Phosphatidic Acids
PubMed: 38484710
DOI: 10.1016/j.chom.2024.02.005 -
Cell Death and Differentiation Mar 2024Lipid droplet (LD) accumulation is a notable feature of obesity-induced cardiomyopathy, while underlying mechanism remains poorly understood. Here we show that mice fed...
Lipid droplet (LD) accumulation is a notable feature of obesity-induced cardiomyopathy, while underlying mechanism remains poorly understood. Here we show that mice fed with high-fat diet (HFD) exhibited significantly increase in cardiac LD and RTN3 expression, accompanied by cardiac function impairment. Multiple loss- and gain-of function experiments indicate that RTN3 is critical to HFD-induced cardiac LD accumulation. Mechanistically, RTN3 directly bonds with fatty acid binding protein 5 (FABP5) to facilitate the directed transport of fatty acids to endoplasmic reticulum, thereby promoting LD biogenesis in a diacylglycerol acyltransferase 2 dependent way. Moreover, lipid overload-induced RTN3 upregulation is due to increased expression of CCAAT/enhancer binding protein α (C/EBPα), which positively regulates RTN3 transcription by binding to its promoter region. Notably, above findings were verified in the myocardium of obese patients. Our findings suggest that manipulating LD biogenesis by modulating RTN3 may be a potential strategy for treating cardiac dysfunction in obese patients.
Topics: Animals; Mice; Cardiomyopathies; Carrier Proteins; Diet, High-Fat; Fatty Acid-Binding Proteins; Heart; Lipid Droplets; Lipids; Membrane Proteins; Mice, Inbred C57BL; Nerve Tissue Proteins; Obesity
PubMed: 38017147
DOI: 10.1038/s41418-023-01241-x -
Journal of Lipid Research Dec 2023Genetic and biochemical evidence has established DDHD-domain containing 2 (DDHD2) as the principal triacylglycerol (TAG) hydrolase in neuronal lipolysis of cytosolic...
Genetic and biochemical evidence has established DDHD-domain containing 2 (DDHD2) as the principal triacylglycerol (TAG) hydrolase in neuronal lipolysis of cytosolic lipid droplets. In this issue of Journal of Lipid Research, Hofer et al. report that DDHD2 cooperates with adipose triglyceride lipase, the principal TAG hydrolase in adipose lipolysis, contributing to cytosolic hydrolysis of both TAG and diacylglycerols in murine neuroblastoma cells and primary cortical neurons via different configurations of the lipases. This finding highlights the complexity of cytosolic acylglycerol hydrolysis and raises many new questions in the field of lipid metabolism.
Topics: Animals; Mice; Lipolysis; Glycerides; Triglycerides; Lipase; Neurons
PubMed: 37871852
DOI: 10.1016/j.jlr.2023.100462 -
Nature Structural & Molecular Biology Jun 2024Sphingomyelin (SM) has key roles in modulating mammalian membrane properties and serves as an important pool for bioactive molecules. SM biosynthesis is mediated by the...
Sphingomyelin (SM) has key roles in modulating mammalian membrane properties and serves as an important pool for bioactive molecules. SM biosynthesis is mediated by the sphingomyelin synthase (SMS) family, comprising SMS1, SMS2 and SMS-related (SMSr) members. Although SMS1 and SMS2 exhibit SMS activity, SMSr possesses ceramide phosphoethanolamine synthase activity. Here we determined the cryo-electron microscopic structures of human SMSr in complexes with ceramide, diacylglycerol/phosphoethanolamine and ceramide/phosphoethanolamine (CPE). The structures revealed a hexameric arrangement with a reaction chamber located between the transmembrane helices. Within this structure, a catalytic pentad E-H/D-H-D was identified, situated at the interface between the lipophilic and hydrophilic segments of the reaction chamber. Additionally, the study unveiled the two-step synthesis process catalyzed by SMSr, involving PE-PLC (phosphatidylethanolamine-phospholipase C) hydrolysis and the subsequent transfer of the phosphoethanolamine moiety to ceramide. This research provides insights into the catalytic mechanism of SMSr and expands our understanding of sphingolipid metabolism.
Topics: Humans; Transferases (Other Substituted Phosphate Groups); Cryoelectron Microscopy; Sphingomyelins; Models, Molecular; Ceramides; Ethanolamines; Phosphatidylethanolamines; Diglycerides; Nerve Tissue Proteins; Membrane Proteins
PubMed: 38388831
DOI: 10.1038/s41594-024-01237-2 -
Journal of Lipid Research Nov 2023Intracellular lipolysis-the enzymatic breakdown of lipid droplet-associated triacylglycerol (TAG)-depends on the cooperative action of several hydrolytic enzymes and...
Intracellular lipolysis-the enzymatic breakdown of lipid droplet-associated triacylglycerol (TAG)-depends on the cooperative action of several hydrolytic enzymes and regulatory proteins, together designated as lipolysome. Adipose triglyceride lipase (ATGL) acts as a major cellular TAG hydrolase and core effector of the lipolysome in many peripheral tissues. Neurons initiate lipolysis independently of ATGL via DDHD domain-containing 2 (DDHD2), a multifunctional lipid hydrolase whose dysfunction causes neuronal TAG deposition and hereditary spastic paraplegia. Whether and how DDHD2 cooperates with other lipolytic enzymes is currently unknown. In this study, we further investigated the enzymatic properties and functions of DDHD2 in neuroblastoma cells and primary neurons. We found that DDHD2 hydrolyzes multiple acylglycerols in vitro and substantially contributes to neutral lipid hydrolase activities of neuroblastoma cells and brain tissue. Substrate promiscuity of DDHD2 allowed its engagement at different steps of the lipolytic cascade: In neuroblastoma cells, DDHD2 functioned exclusively downstream of ATGL in the hydrolysis of sn-1,3-diacylglycerol (DAG) isomers but was dispensable for TAG hydrolysis and lipid droplet homeostasis. In primary cortical neurons, DDHD2 exhibited lipolytic control over both, DAG and TAG, and complemented ATGL-dependent TAG hydrolysis. We conclude that neuronal cells use noncanonical configurations of the lipolysome and engage DDHD2 as dual TAG/DAG hydrolase in cooperation with ATGL.
Topics: Humans; Lipase; Lipolysis; Neurons; Paraplegia; Phospholipases; Triglycerides
PubMed: 37832604
DOI: 10.1016/j.jlr.2023.100457 -
Plant Physiology and Biochemistry : PPB Dec 2023Lipids are the main components of plant cell biofilms and play a crucial role in plant growth, Understanding the modulation in lipid profiles under heat stress can...
Lipids are the main components of plant cell biofilms and play a crucial role in plant growth, Understanding the modulation in lipid profiles under heat stress can contribute to understanding the heat tolerance mechanisms in wheat leaves. In the current study, two wheat cultivars with different heat tolerance levels were treated with optimum temperature (OT) and high temperature (HT) at the flowering stage, and the antioxidant enzyme activity in the leaves and the grain yield were determined. Further, lipidomics was studied to determine the changes in lipid composition in the leaves. The heat-tolerant cultivar ZM7698 exhibited higher antioxidant enzyme activity and lower malondialdehyde and HO contents. High-temperature stress led to the remodeling of lipid profile in the two cultivars. The relative proportion of digalactosyl diacylglycerol (DGDG) and phosphatidylinositol (PI) components increased in the heat-tolerant cultivar under high-temperature stress, while it was decreased in the heat-sensitive cultivar. The lipid unsaturation levels of sulfoquinovosyl diacylglycerol (SQDG), monogalactosyl monoacylglycerol (MGMG), and phosphatidic acid (PA) decreased significantly in the heat-tolerant cultivar under high-temperature stress. The increase in unsaturation of monogalactosyl diacylglycerol (MGDG) and phosphatidylethanolamine (PE) in the heat-tolerant cultivar under high-temperature stress was lower than in the heat-sensitive cultivar. In addition, a high sitosterol/stigmasterol (SiE/StE) ratio was observed in heat-tolerant cultivar under high-temperature stress. Taken together, these results revealed that a heat-tolerant cultivar could enhance its ability to resist heat stress by modulating the composition and ratio of the lipid components and decreasing lipid unsaturation levels in wheat.
Topics: Antioxidants; Triticum; Diglycerides; Hydrogen Peroxide; Lipidomics; Heat-Shock Response; Stress, Physiological
PubMed: 37988880
DOI: 10.1016/j.plaphy.2023.108190 -
Current Opinion in Cell Biology Jun 2024Lipid droplets (LDs) are cytoplasmic organelles, but they are also found within the nucleus in small numbers. Nuclear LDs that form at the inner nuclear membrane (INM)... (Review)
Review
Lipid droplets (LDs) are cytoplasmic organelles, but they are also found within the nucleus in small numbers. Nuclear LDs that form at the inner nuclear membrane (INM) often increase in response to perturbation in phosphatidic acid (PA) and/or diacylglycerol (DAG), both implicated in various INM functions. Nuclear LDs also increase upon downregulation of seipin, a protein that can trap PA and DAG in the endoplasmic reticulum. Notably, both PA and DAG appear to be more densely distributed on the surface of nuclear LDs than in the INM. I propose that nuclear LDs play a role in regulating the PA and DAG level in the INM, thereby contributing to the lipid homeostasis in this compartment.
Topics: Nuclear Envelope; Homeostasis; Lipid Droplets; Humans; Animals; Lipid Metabolism; Phosphatidic Acids; Diglycerides; Cell Nucleus; Endoplasmic Reticulum
PubMed: 38744005
DOI: 10.1016/j.ceb.2024.102370