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Immunological Reviews Nov 2022Extracellular vesicles (EVs) are small membrane-bound vesicles released by cells under various conditions. They are found in the extracellular milieu in all biological... (Review)
Review
Extracellular vesicles (EVs) are small membrane-bound vesicles released by cells under various conditions. They are found in the extracellular milieu in all biological fluids. As the concentrations, contents, and origin of EVs can change during inflammation, the assessment of EVs can be used as a proxy of cellular activation. Here, we review the literature regarding EVs, more particularly those released by platelets and their mother cells, the megakaryocytes. Their cargo includes cytokines, growth factors, organelles (mitochondria and proteasomes), nucleic acids (messenger and non-coding RNA), transcription factors, and autoantigens. EVs may thus contribute to intercellular communication by facilitating exchange of material between cells. EVs also interact with other molecules secreted by cells. In autoimmune diseases, EVs are associated with antibodies secreted by B cells. By definition, EVs necessarily comprise a phospholipid moiety, which is thus the target of secreted phospholipases also abundantly expressed in the extracellular milieu. We discuss how platelet-derived EVs, which represent the majority of the circulating EVs, may contribute to immunity through the activity of their cargo or in combination with the secretory interactome.
Topics: Autoantigens; Cytokines; Extracellular Vesicles; Humans; Nucleic Acids; Phospholipases; Phospholipids; RNA, Untranslated; Transcription Factors
PubMed: 35899405
DOI: 10.1111/imr.13119 -
Chemosphere Mar 2021Venom geographical variation is common among venomous animals. This phenomenon presents problems in the development of clinical treatments and medicines against...
Venom geographical variation is common among venomous animals. This phenomenon presents problems in the development of clinical treatments and medicines against envenomation. The venomous giant jellyfish Nemopilema nomurai, Scyphozoan, is a blooming jellyfish species in the Yellow Sea and the East China Sea that causes numerous jellyfish sting cases every year. Metalloprotease and phospholipase A (PLA) are the main components in Nemopilema nomurai venom and may activate many toxicities, such as hemolysis, inflammation and lethality. Geographical variation in the content and activity of these enzymes may cause different symptoms and therapeutic problems. For the first time, we verified metalloprotease and PLA geographical variation in Nemopilema nomurai venom by performing a comparative analysis of 31 venom samples by SDS-PAGE, analyzing protease zymography, enzymatic activity, and drawing contour maps. Band locations and intensities of SDS-PAGE and protease zymograms showed geographical differences. The enzymatic activities of both metalloprotease and PLA showed a trend of geographic regularity. The distribution patterns of these activities are directly shown in contour maps. Metalloproteinase activity was lower near the coast. PLA-like activity was lower in the Southern Yellow Sea. We surmised that metalloproteinase and PLA-like activities might be related to venom ontogeny and species abundance respectively, and influenced by similar environmental factors. This study provides a theoretical basis for further ecological and medical studies of Nemopilema nomurai jellyfish venom.
Topics: Animals; China; Cnidarian Venoms; Metalloproteases; Phospholipases; Scyphozoa
PubMed: 33310516
DOI: 10.1016/j.chemosphere.2020.129164 -
Kidney International Mar 2023The M-type phospholipase A2 receptor (PLA2R) is the major autoantigen of primary membranous nephropathy (MN). Despite many studies on B-cell epitopes recognized by...
The M-type phospholipase A2 receptor (PLA2R) is the major autoantigen of primary membranous nephropathy (MN). Despite many studies on B-cell epitopes recognized by antibodies, little is known about T-cell epitopes. Herein, we synthesized 123 linear peptides, each consisting of 15-22 amino acids with 8-12 amino acid overlaps, across ten domains of PLA2R. Their binding capacity to risk (DRB1∗1501, DRB1∗0301) and protective (DRB1∗0901, DRB1∗0701) HLA molecules was then assessed by flow cytometry. Proliferation of CD4+ T cells from patients with anti-PLA2R positive MN was analyzed after peptide stimulation. Cytokines produced by activated peripheral blood mononuclear cells were measured by cytometric bead arrays. We identified 17 PLA2R peptides that bound to both DRB1∗1501 and DRB1∗0301 molecules with high capacity. Some of these peptides showed decreased binding to heterozygous DRB1∗1501/0901 and DRB1∗0301/0701. Ten of the 17 peptides (CysR1, CysR10, CysR12, FnII-3, CTLD3-9, CTLD3-10, CTLD3-11, CTLD5-2-1, CTLD7-1 and CTLD7-2) induced significant proliferation of CD4+ T cells from patients with MN than cells from healthy individuals. Upon activation by these peptides, peripheral blood mononuclear cells from patients with MN produced higher levels of pro-inflammatory cytokines, predominantly IL-6, TNF-α, IL-10, IL-9 and IL-17. Thus, we mapped and identified ten peptides in the CysR, FnII, CTLD3, CTLD5, and CTLD7 domains of PLA2R as potential T-cell epitopes of MN. These findings are a first step towards developing peptide-specific immunotherapies.
Topics: Humans; Glomerulonephritis, Membranous; Epitopes, T-Lymphocyte; Receptors, Phospholipase A2; Leukocytes, Mononuclear; Amino Acids; Phospholipases A2; Cytokines; Autoantibodies
PubMed: 36549363
DOI: 10.1016/j.kint.2022.11.021 -
Plant Physiology Apr 2021Heat shock proteins (HSPs) function as molecular chaperones and are key components responsible for protein folding, assembly, translocation, and degradation under stress...
Heat shock proteins (HSPs) function as molecular chaperones and are key components responsible for protein folding, assembly, translocation, and degradation under stress conditions. However, little is known about how HSPs stabilize proteins and membranes in response to different hormonal or environmental cues in plants. Here, we combined molecular, biochemical, and genetic approaches to elucidate the involvement of cytosolic HSP70-3 in plant stress responses and the interplay between HSP70-3 and plasma membrane (PM)-localized phospholipase Dδ (PLDδ) in Arabidopsis (Arabidopsis thaliana). Analysis using pull-down, coimmunoprecipitation, and bimolecular fluorescence complementation revealed that HSP70-3 specifically interacted with PLDδ. HSP70-3 bound to microtubules, such that it stabilized cortical microtubules upon heat stress. We also showed that heat shock induced recruitment of HSP70-3 to the PM, where HSP70-3 inhibited PLDδ activity to mediate microtubule reorganization, phospholipid metabolism, and plant thermotolerance, and this process depended on the HSP70-3-PLDδ interaction. Our results suggest a model whereby the interplay between HSP70-3 and PLDδ facilitates the re-establishment of cellular homeostasis during plant responses to external stresses and reveal a regulatory mechanism in regulating membrane lipid metabolism.
Topics: Arabidopsis; Arabidopsis Proteins; Cell Membrane; HSP70 Heat-Shock Proteins; Heat-Shock Response; Microtubules; Phospholipase D; Phospholipases
PubMed: 33793918
DOI: 10.1093/plphys/kiaa083 -
Molecules (Basel, Switzerland) Apr 2022Phospholipase A (PLA) is an enzyme that cleaves an ester bond at the -1 position of glycerophospholipids, producing a free fatty acid and a lysophospholipid. PLA... (Review)
Review
Phospholipase A (PLA) is an enzyme that cleaves an ester bond at the -1 position of glycerophospholipids, producing a free fatty acid and a lysophospholipid. PLA activities have been detected both extracellularly and intracellularly, which are well conserved in higher eukaryotes, including fish and mammals. All extracellular PLAs belong to the lipase family. In addition to PLA activity, most mammalian extracellular PLAs exhibit lipase activity to hydrolyze triacylglycerol, cleaving the fatty acid and contributing to its absorption into the intestinal tract and tissues. Some extracellular PLAs exhibit PLA activities specific to phosphatidic acid (PA) or phosphatidylserine (PS) and serve to produce lysophospholipid mediators such as lysophosphatidic acid (LPA) and lysophosphatidylserine (LysoPS). A high level of PLA activity has been detected in the cytosol fractions, where PA-PLA/DDHD1/iPLA was responsible for the activity. Many homologs of PA-PLA and PLA have been shown to exhibit PLA activity. Although much has been learned about the pathophysiological roles of PLA molecules through studies of knockout mice and human genetic diseases, many questions regarding their biochemical properties, including their genuine in vivo substrate, remain elusive.
Topics: Animals; Lipase; Lysophospholipids; Mammals; Mice; Phospholipases A1
PubMed: 35458682
DOI: 10.3390/molecules27082487 -
Advances in Biological Regulation Jan 2023Mutated genes of the RAS family encoding small GTP-binding proteins drive numerous cancers, including pancreatic, colon and lung tumors. Besides the numerous effects of...
Mutated genes of the RAS family encoding small GTP-binding proteins drive numerous cancers, including pancreatic, colon and lung tumors. Besides the numerous effects of mutant RAS gene expression on aberrant proliferation, transformed phenotypes, metabolism, and therapy resistance, the most striking consequences of chronic RAS activation are changes of the genetic program. By performing systematic gene expression studies in cellular models that allow comparisons of pre-neoplastic with RAS-transformed cells, we and others have estimated that 7 percent or more of all transcripts are altered in conjunction with the expression of the oncogene. In this context, the number of up-regulated transcripts approximates that of down-regulated transcripts. While up-regulated transcription factors such as MYC, FOSL1, and HMGA2 have been identified and characterized as RAS-responsive drivers of the altered transcriptome, the suppressed factors have been less well studied as potential regulators of the genetic program and transformed phenotype in the breadth of their occurrence. We therefore have collected information on downregulated RAS-responsive factors and discuss their potential role as tumor suppressors that are likely to antagonize active cancer drivers. To better understand the active mechanisms that entail anti-RAS function and those that lead to loss of tumor suppressor activity, we focus on the tumor suppressor HREV107 (alias PLAAT3 [Phospholipase A and acyltransferase 3], PLA2G16 [Phospholipase A2, group XVI] and HRASLS3 [HRAS-like suppressor 3]). Inactivating HREV107 mutations in tumors are extremely rare, hence epigenetic causes modulated by the RAS pathway are likely to lead to down-regulation and loss of function.
Topics: Humans; Transcriptome; Signal Transduction; Genes, Tumor Suppressor; Lung Neoplasms; Phospholipases A2; Gene Expression Regulation, Neoplastic
PubMed: 36513579
DOI: 10.1016/j.jbior.2022.100936 -
The Journal of Biological Chemistry May 2022Lipids play critical roles in several major chronic diseases of our times, including those that involve inflammatory sequelae such as metabolic syndrome including... (Review)
Review
Lipids play critical roles in several major chronic diseases of our times, including those that involve inflammatory sequelae such as metabolic syndrome including obesity, insulin sensitivity, and cardiovascular diseases. However, defining the substrate specificity of enzymes of lipid metabolism is a challenging task. For example, phospholipase A (PLA) enzymes constitute a superfamily of degradative, biosynthetic, and signaling enzymes that all act stereospecifically to hydrolyze and release the fatty acids of membrane phospholipids. This review focuses on how membranes interact allosterically with enzymes to regulate cell signaling and metabolic pathways leading to inflammation and other diseases. Our group has developed "substrate lipidomics" to quantify the substrate phospholipid specificity of each PLA and coupled this with molecular dynamics simulations to reveal that enzyme specificity is linked to specific hydrophobic binding subsites for membrane phospholipid substrates. We have also defined unexpected headgroup and acyl chain specificity for each of the major human PLA enzymes, which explains the observed specificity at a structural level. Finally, we discovered that a unique hydrophobic binding site-and not each enzyme's catalytic residues or polar headgroup binding site-predominantly determines enzyme specificity. We also discuss how PLAs release specific fatty acids after allosteric enzyme association with membranes and extraction of the phospholipid substrate, which can be blocked by stereospecific inhibitors. After decades of work, we can now correlate PLA specificity and inhibition potency with molecular structure and physiological function.
Topics: Allosteric Regulation; Fatty Acids; Humans; Phospholipases A2; Phospholipids; Substrate Specificity
PubMed: 35358512
DOI: 10.1016/j.jbc.2022.101873 -
Scientific Reports Mar 2022Since the clinical outcome of patients with sarcoidosis is still unpredictable, a good prognostic biomarker is necessary. Autotaxin (ATX) and phosphatidylserine-specific...
Since the clinical outcome of patients with sarcoidosis is still unpredictable, a good prognostic biomarker is necessary. Autotaxin (ATX) and phosphatidylserine-specific phospholipase A1 (PS-PLA1) function as main enzymes to produce lysophospholipids (LPLs), and these enzymes are attracting attention as useful biomarkers for several chronic inflammatory diseases. Here, we investigated the relationships between LPLs-producing enzymes and the disease activity of sarcoidosis. In total, 157 patients with sarcoidosis (active state, 51%) were consecutively enrolled. Using plasma or urine specimens, we measured the values of LPLs-producing enzymes. Urine ATX (U-ATX) levels were significantly lower in the active state compared to those in the inactive state, while the plasma ATX (P-ATX) and PS-PLA1 levels showed no significant difference between these two states. Concerning the comparison with existing clinical biomarkers for sarcoidosis, U-ATX showed a weak negative correlation to ACE, P-ATX a weak positive correlation to both ACE and sIL-2R, and PS-PLA1 a weak positive one to sIL-2R. Notably, only the U-ATX levels inversely fluctuated depending on the status of disease activity whether OCS had been used or not. These findings suggest that U-ATX is likely to be a novel and useful molecule for assessing the disease activity of sarcoidosis.
Topics: Biomarkers; Body Fluids; Humans; Lysophospholipids; Phospholipases A1; Phosphoric Diester Hydrolases; Sarcoidosis
PubMed: 35288647
DOI: 10.1038/s41598-022-08388-6 -
Molecular Diversity Aug 2023The involvement of Trypanosoma congolense sialidase alongside phospholipase A has been widely accepted as the major contributing factor to anemia during African animal...
The involvement of Trypanosoma congolense sialidase alongside phospholipase A has been widely accepted as the major contributing factor to anemia during African animal trypanosomiasis. The enzymes aid the parasite in scavenging sialic acid and fatty acids necessary for survival in the infected host, but there are no specific drug candidates against the two enzymes. This study investigated the inhibitory effects of β-sitosterol on the partially purified T. congolense sialidase and phospholipase A. Purification of the enzymes using DEAE cellulose column led to fractions with highest specific activities of 8016.41 and 39.26 µmol/min/mg for sialidase and phospholipase A, respectively. Inhibition kinetics studies showed that β-sitosterol is non-competitive and an uncompetitive inhibitor of sialidase and phospholipase A with inhibition binding constants of 0.368 and 0.549 µM, respectively. Molecular docking of the compound revealed binding energies of - 8.0 and - 8.6 kcal/mol against the sialidase and phospholipase A, respectively. Furthermore, 100 ns molecular dynamics simulation using GROMACS revealed stable interaction of β-sitosterol with both enzymes. Hydrogen bond interactions between the ligand and Glu284 and Leu102 residues of the sialidase and phospholipase A, respectively, were found to be the major stabilizing forces. In conclusion, β-sitosterol could serve as a dual inhibitor of T. congolense sialidase and phospholipase A hence, the compound could be exploited further in the search for newer trypanocides.
Topics: Animals; Molecular Dynamics Simulation; Neuraminidase; Trypanosoma congolense; Molecular Docking Simulation; Kinetics; Trypanosomiasis, African; Phospholipases
PubMed: 36042119
DOI: 10.1007/s11030-022-10517-2 -
Nucleic Acids Research Jan 2024The phospholipase D (PLD) family is comprised of enzymes bearing phospholipase activity towards lipids or endo- and exonuclease activity towards nucleic acids. PLD3 is...
The phospholipase D (PLD) family is comprised of enzymes bearing phospholipase activity towards lipids or endo- and exonuclease activity towards nucleic acids. PLD3 is synthesized as a type II transmembrane protein and proteolytically cleaved in lysosomes, yielding a soluble active form. The deficiency of PLD3 leads to the slowed degradation of nucleic acids in lysosomes and chronic activation of nucleic acid-specific intracellular toll-like receptors. While the mechanism of PLD phospholipase activity has been extensively characterized, not much is known about how PLDs bind and hydrolyze nucleic acids. Here, we determined the high-resolution crystal structure of the luminal N-glycosylated domain of human PLD3 in its apo- and single-stranded DNA-bound forms. PLD3 has a typical phospholipase fold and forms homodimers with two independent catalytic centers via a newly identified dimerization interface. The structure of PLD3 in complex with an ssDNA-derived thymidine product in the catalytic center provides insights into the substrate binding mode of nucleic acids in the PLD family. Our structural data suggest a mechanism for substrate binding and nuclease activity in the PLD family and provide the structural basis to design immunomodulatory drugs targeting PLD3.
Topics: Humans; Lysosomes; Phospholipase D; Phospholipases; Exodeoxyribonucleases
PubMed: 37994783
DOI: 10.1093/nar/gkad1114