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European Journal of Medicinal Chemistry Aug 2023Cells latently infected with human immunodeficiency virus type 1 (HIV-1) prevent people living with HIV-1 from obtaining a cure to the infectious disease. Latency...
Cells latently infected with human immunodeficiency virus type 1 (HIV-1) prevent people living with HIV-1 from obtaining a cure to the infectious disease. Latency reversing agents (LRAs) such as protein kinase C (PKC) activators and histone deacetylase (HDAC) inhibitors can reactivate cells latently infected with HIV-1. Several trials based on treatment with HDAC inhibitors alone, however, failed to reduce the number of latent HIV-1 reservoirs. Herein, we have focused on a diacylglycerol (DAG)-lactone derivative, YSE028 (1), which is a PKC activator with latency reversing activity and no significant cytotoxicity. Caspase-3 activation of YSE028 (1) led to cell apoptosis, specifically in HIV-1 latently infected cells. Structure-activity relationship studies of YSE028 (1) have produced several useful derivatives. Among these, compound 2 is approximately ten times more potent than YSE028 (1) in reactivation of cells latently infected with HIV-1. The activity of DAG-lactone derivatives was correlated with the binding affinity for PKC and the stability against esterase-mediated hydrolysis.
Topics: Humans; CD4-Positive T-Lymphocytes; Diglycerides; Histone Deacetylase Inhibitors; HIV Infections; HIV-1; Protein Kinase C; Virus Activation; Virus Latency
PubMed: 37224601
DOI: 10.1016/j.ejmech.2023.115449 -
Nature May 2020Diacylglycerol O-acyltransferase 1 (DGAT1) synthesizes triacylglycerides and is required for dietary fat absorption and fat storage in humans. DGAT1 belongs to the...
Diacylglycerol O-acyltransferase 1 (DGAT1) synthesizes triacylglycerides and is required for dietary fat absorption and fat storage in humans. DGAT1 belongs to the membrane-bound O-acyltransferase (MBOAT) superfamily, members of which are found in all kingdoms of life and are involved in the acylation of lipids and proteins. How human DGAT1 and other mammalian members of the MBOAT family recognize their substrates and catalyse their reactions is unknown. The absence of three-dimensional structures also hampers rational targeting of DGAT1 for therapeutic purposes. Here we present the cryo-electron microscopy structure of human DGAT1 in complex with an oleoyl-CoA substrate. Each DGAT1 protomer has nine transmembrane helices, eight of which form a conserved structural fold that we name the MBOAT fold. The MBOAT fold in DGAT1 forms a hollow chamber in the membrane that encloses highly conserved catalytic residues. The chamber has separate entrances for each of the two substrates, fatty acyl-CoA and diacylglycerol. DGAT1 can exist as either a homodimer or a homotetramer and the two forms have similar enzymatic activity. The N terminus of DGAT1 interacts with the neighbouring protomer and these interactions are required for enzymatic activity.
Topics: Acyl Coenzyme A; Binding Sites; Cryoelectron Microscopy; Diacylglycerol O-Acyltransferase; Diglycerides; Humans; Models, Molecular; Protein Multimerization; Structure-Activity Relationship; Triglycerides
PubMed: 32433610
DOI: 10.1038/s41586-020-2280-2 -
FEBS Letters Aug 2016Lipids are commonly known for the structural roles they play, however, the specific contribution of different lipid classes to wide-ranging signalling pathways is... (Review)
Review
Lipids are commonly known for the structural roles they play, however, the specific contribution of different lipid classes to wide-ranging signalling pathways is progressively being unravelled. Signalling lipids and their associated effector proteins are emerging as significant contributors to a vast array of effector functions within cells, including essential processes such as membrane fusion and vesicle exocytosis. Many phospholipids have signalling capacity, however, this review will focus on phosphatidic acid (PA) and the enzymes implicated in its production from diacylglycerol (DAG) and phosphatidylcholine (PC): DGK and PLD respectively. PA is a negatively charged, cone-shaped lipid identified as a key mediator in specific membrane fusion and vesicle exocytosis events in a variety of mammalian cells, and has recently been implicated in specialised secretory organelle exocytosis in apicomplexan parasites. This review summarises the recent work implicating a role for PA regulation in exocytosis in various cell types. We will discuss how these signalling events are linked to pathogenesis in the phylum Apicomplexa.
Topics: Apicomplexa; Diglycerides; Exocytosis; Lipid Metabolism; Lipids; Phosphatidic Acids; Phosphatidylcholines; Signal Transduction
PubMed: 27403735
DOI: 10.1002/1873-3468.12296 -
Insect Biochemistry and Molecular... Jul 2015The insect fat body and the adipose tissue of vertebrates store fatty acids (FA) as triacylglycerols (TG). However, the fat body of most insects has the unique ability...
The insect fat body and the adipose tissue of vertebrates store fatty acids (FA) as triacylglycerols (TG). However, the fat body of most insects has the unique ability to rapidly produce and secrete large amounts of diacylglycerol (DG). Monoacylglycerol acyltransferase (MGAT), which catalyzes the synthesis of DG from MG, and a diacylglycerol acyltransferase (DGAT), which catalyzes the synthesis of TG from DG, are key enzymes in the metabolism of neutral glycerides. However, very little is known about these acyltransferases in insects. In the present study we have cloned two predicted MGATs and a DGAT from Manduca sexta and compared their sequences with predicted MGAT and DGAT homologs from a number of insect species. The comparison suggested that insects may only have a single DGAT gene, DGAT1. The apparent absence of a DGAT2 gene in insects would represent a major difference with vertebrates, which contain DGAT1 and DGAT2 genes. Insects seem to have a single MGAT gene which is similar to the MGAT2 of vertebrates. A number of conserved phosphorylation sites of potential physiological significance were identified among insect proteins and among insect and vertebrate proteins. DGAT1 and MGAT are expressed in fat body, midgut and ovaries. The relative rates of utilization of FAs for the synthesis of DG and TG correlated with the relative expression levels of MGAT and DGAT suggesting that regulation of the expression levels of these acyltransferases could be determining whether the fat body secretes DG or stores fatty acids as TG. The expression patterns of the acyltransferases suggest a role of the monoacylglycerol pathway in the production and mobilization of DG in M. sexta fat body.
Topics: Acyltransferases; Animals; Diacylglycerol O-Acyltransferase; Diglycerides; Fat Body; Female; Gastrointestinal Tract; Gene Expression Regulation; Male; Manduca; Monoglycerides; Ovary; Triglycerides
PubMed: 25263765
DOI: 10.1016/j.ibmb.2014.09.007 -
Biochimica Et Biophysica Acta.... Oct 2019Lipins are phosphatidic acid phosphatase enzymes whose cellular function in regulating lipid metabolism has been known for decades, particularly in metabolically active... (Review)
Review
Lipins are phosphatidic acid phosphatase enzymes whose cellular function in regulating lipid metabolism has been known for decades, particularly in metabolically active tissues such as adipose tissue or liver. In recent years evidence is accumulating for key regulatory roles of the lipin family in innate immune cells. Lipins may help regulate signaling through relevant immune receptors such as Toll-like receptors, and are also integral part of the cellular machinery for lipid storage in these cells, thereby modulating certain inflammatory processes. Mutations in genes that encode for members of this family produce autoinflammatory hereditary diseases or diseases with an important inflammatory component in humans. In this review we summarize recent findings on the role of lipins in cells of the innate immune system and in the onset and progress of inflammatory processes.
Topics: Animals; Diglycerides; Humans; Immunity, Innate; Inflammation; Macrophages; Phosphatidate Phosphatase; Phosphatidic Acids
PubMed: 31220616
DOI: 10.1016/j.bbalip.2019.06.003 -
Nutrients Nov 2022Lipid droplet is a dynamic organelle that undergoes periods of biogenesis and degradation under environmental stimuli. The excessive accumulation of lipid droplets is...
Lipid droplet is a dynamic organelle that undergoes periods of biogenesis and degradation under environmental stimuli. The excessive accumulation of lipid droplets is the major characteristic of non-alcoholic fatty liver disease (NAFLD). Moderate aerobic exercise is a powerful intervention protecting against the progress of NAFLD. However, its impact on lipid droplet dynamics remains ambiguous. Mice were fed with 15 weeks of high-fat diet in order to induce NAFLD. Meanwhile, the mice performed 15 weeks of treadmill exercise. Our results showed that 15 weeks of regular moderate treadmill exercise alleviated obesity, insulin intolerance, hyperlipidemia, and hyperglycemia induced by HFD. Importantly, exercise improved histological phenotypes of NAFLD, including hepatic steatosis, inflammation, and locular ballooning, as well as prevented liver fat deposition and liver injury induced by HFD. Exercise reduced hepatic lipid droplet size, and moreover, it reduced PLIN2 protein level and increased PLIN3 protein level in the liver of HFD mice. Interestingly, our results showed that exercise did not significantly affect the gene expressions of , , or , which were involved in TG synthesis. However, it did reduce the expressions of FITM2, , and , which were major involved in lipid droplet growth and budding, and lipid droplet expansion. In addition, exercise reduced ATGL protein level in HFD mice, and regulated lipophagy-related markers, including increasing ATG5, LAMP1, LAMP2, LAL, and CTSD, decreasing LC3II/I and p62, and promoting colocalization of LAMP1 with LDs. In summary, our data suggested that 15 weeks of moderate treadmill exercise was beneficial for regulating liver lipid droplet dynamics in HFD mice by inhibiting abnormal lipid droplets expansion and enhancing clearance of lipid droplets by lysosomes during the lipophagic process, which might provide highly flexible turnover for lipid mobilization and metabolism. Abbreviations: β-actin: actin beta; ATG5: autophagy related 5; LAMP2: lysosomal-associated membrane protein 2; LAMP1: lysosomal-associated membrane protein 1; SQSTM1/p62: sequestosome 1; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; ATGL: adipose triglyceride lipase; CSTD: cathepsin D; LAL: lysosomal acid lipase; DGAT1: diacylglycerol-o-acyltransferase 1; DGAT2: diacylglycerol-o-acyltransferase 2; CIDEA: cell death inducing dffa-like effector a; CIDEC/FSP27: cell death inducing dffa-like effector c; FITM2: fat storage-inducing transmembrane protein 2; PLIN2: adipose differentiation related protein; PLN3: tail-interacting protein 47; HSP90: heat shock protein 90; SREBP1c: sterol regulatory element binding protein-1c; chREBP: carbohydrate response element binding protein.
Topics: Mice; Animals; Non-alcoholic Fatty Liver Disease; Lipid Droplets; Diglycerides; Autophagy; Perilipin-2; Sterol Regulatory Element Binding Protein 1; Diacylglycerol O-Acyltransferase
PubMed: 36432597
DOI: 10.3390/nu14224910 -
Molecular Oncology Nov 2023Hepatocellular carcinoma (HCC) is largely associated with aberrant activation of Wnt/β-catenin signaling. Nevertheless, how membrane lipid composition is altered in HCC... (Comparative Study)
Comparative Study
Hepatocellular carcinoma (HCC) is largely associated with aberrant activation of Wnt/β-catenin signaling. Nevertheless, how membrane lipid composition is altered in HCC cells with abnormal Wnt signaling remains elusive. Here, by exploiting comprehensive lipidome profiling, we unravel the membrane lipid composition of six different HCC cell lines with mutations in components of Wnt/β-catenin signaling, leading to differences in their endogenous signaling activity. Among the differentially regulated lipids are diacylglycerol (DAG) and ceramide, which were downregulated at the membrane of HCC cells after Wnt3a treatment. DAG and ceramide enhanced Wnt/β-catenin signaling by inducing caveolin-mediated endocytosis of the canonical Wnt-receptor complex, while their depletion suppressed the signaling activity along with a reduction of caveolin-mediated endocytosis in SNU475 and HepG2 cells. Moreover, depletion of DAG and ceramide significantly impeded the proliferation, tumor growth, and in vivo migration capacity of SNU475 and HepG2 cells. This study, by pioneering plasma membrane lipidome profiling in HCC cells, exhibits the remarkable potential of lipids to correct dysregulated signaling pathways in cancer and stop abnormal tumor growth.
Topics: Humans; beta Catenin; Carcinoma, Hepatocellular; Caveolins; Cell Line, Tumor; Cell Proliferation; Ceramides; Diglycerides; Lipidomics; Liver Neoplasms; Wnt Signaling Pathway
PubMed: 37699867
DOI: 10.1002/1878-0261.13520 -
The Journal of Biological Chemistry Jun 2020The transient receptor potential vanilloid 1 (TRPV1) channel is activated by heat and by capsaicin, the pungent compound in chili peppers. Calcium influx through TRPV1...
The transient receptor potential vanilloid 1 (TRPV1) channel is activated by heat and by capsaicin, the pungent compound in chili peppers. Calcium influx through TRPV1 has been shown to activate a calcium-sensitive phospholipase C (PLC) enzyme and to lead to a robust decrease in phosphatidylinositol 4,5-bisphosphate [PI(4,5)P] levels, which is a major contributor to channel desensitization. Diacylglycerol (DAG), the product of the PLC-catalyzed PI(4,5)P hydrolysis, activates protein kinase C (PKC). PKC is known to potentiate TRPV1 activity during activation of G protein-coupled receptors, but it is not known whether DAG modulates TRPV1 during desensitization. We found here that inhibition of diacylglycerol kinase (DAGK) enzymes reduces desensitization of native TRPV1 in dorsal root ganglion neurons as well as of recombinant TRPV1 expressed in HEK293 cells. The effect of DAGK inhibition was eliminated by mutating two PKC-targeted phosphorylation sites, Ser-502 and Ser-800, indicating involvement of PKC. TRPV1 activation induced only a small and transient increase in DAG levels, unlike the robust and more sustained increase induced by muscarinic receptor activation. DAGK inhibition substantially increased the DAG signal evoked by TRPV1 activation but not that evoked by M1 muscarinic receptor activation. Our results show that Ca influx through TRPV1 activates PLC and DAGK enzymes and that the latter limits formation of DAG and negatively regulates TRPV1 channel activity. Our findings uncover a role of DAGK in ion channel regulation.
Topics: Animals; Calcium; Capsaicin; Cell Membrane; Cytoplasm; Diacylglycerol Kinase; Diglycerides; HEK293 Cells; Humans; Ion Channel Gating; Mice, Inbred C57BL; Models, Biological; Phosphatidylinositol 4,5-Diphosphate; Protein Kinase C; Protein Kinase Inhibitors; Rats; Ritanserin; TRPV Cation Channels
PubMed: 32345612
DOI: 10.1074/jbc.RA119.012505 -
Lipids in Health and Disease May 2020Protein kinase C (PKC) and Protein kinase D (PKD) isoforms can sense diacylglycerol (DAG) generated in the different cellular compartments in various physiological... (Review)
Review
Protein kinase C (PKC) and Protein kinase D (PKD) isoforms can sense diacylglycerol (DAG) generated in the different cellular compartments in various physiological processes. DAG accumulates in multiple organs of the obese subjects, which leads to the disruption of metabolic homeostasis and the development of diabetes as well as associated diseases. Multiple studies proved that aberrant activation of PKCs and PKDs contributes to the development of metabolic diseases. DAG-sensing PKC and PKD isoforms play a crucial role in the regulation of metabolic homeostasis and therefore might serve as targets for the treatment of metabolic disorders such as obesity and diabetes.
Topics: Animals; Diabetes Mellitus; Diglycerides; Glucose; Humans; Insulin; Lipid Metabolism; Obesity; Protein Kinase C; Signal Transduction
PubMed: 32466765
DOI: 10.1186/s12944-020-01286-8 -
Biochemistry Apr 2021Munc13-1 is a presynaptic active zone protein that acts as a master regulator of synaptic vesicle priming and neurotransmitter release in the brain. It has been...
Munc13-1 is a presynaptic active zone protein that acts as a master regulator of synaptic vesicle priming and neurotransmitter release in the brain. It has been implicated in the pathophysiology of several neurodegenerative diseases. Diacylglycerol and phorbol ester activate Munc13-1 by binding to its C1 domain. The objective of this study is to identify the structural determinants of ligand binding activity of the Munc13-1 C1 domain. Molecular docking suggested that residues Trp-588, Ile-590, and Arg-592 of Munc13-1 are involved in ligand interactions. To elucidate the role of these three residues in ligand binding, we generated W588A, I590A, and R592A mutants in full-length Munc13-1, expressed them as GFP-tagged proteins in HT22 cells, and measured their ligand-induced membrane translocation by confocal microscopy and immunoblotting. The extent of 1,2-dioctanoyl--glycerol (DOG)- and phorbol ester-induced membrane translocation decreased in the following order: wild type > I590A > W588A > R592A and wild type > W588A > I590A > R592A, respectively. To understand the effect of the mutations on ligand binding, we also measured the DOG binding affinity of the isolated wild-type C1 domain and its mutants in membrane-mimicking micelles using nuclear magnetic resonance methods. The DOG binding affinity decreased in the following order: wild type > I590A > R592A. No binding was detected for W588A with DOG in micelles. This study shows that Trp-588, Ile-590, and Arg-592 are essential determinants for the activity of Munc13-1 and the effects of the three residues on the activity are ligand-dependent. This study bears significance for the development of selective modulators of Munc13-1.
Topics: Binding Sites; Cell Line; Diglycerides; Humans; Models, Molecular; Nerve Tissue Proteins; Protein Binding; Protein Conformation
PubMed: 33818064
DOI: 10.1021/acs.biochem.1c00165