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2.
Cell Mol Life Sci ; 81(1): 191, 2024 Apr 23.
Article in English | MEDLINE | ID: mdl-38652315

ABSTRACT

Lipopolysaccharide (LPS) induces a strong pro-inflammatory reaction of macrophages upon activation of Toll-like receptor 4 (TLR4) with the assistance of CD14 protein. Considering a key role of plasma membrane rafts in CD14 and TLR4 activity and the significant impact exerted on that activity by endocytosis and intracellular trafficking of the both LPS acceptors, it seemed likely that the pro-inflammatory reaction could be modulated by flotillins. Flotillin-1 and -2 are scaffolding proteins associated with the plasma membrane and also with endo-membranes, affecting both the plasma membrane dynamics and intracellular protein trafficking. To verify the above hypothesis, a set of shRNA was used to down-regulate flotillin-2 in Raw264 cells, which were found to also become deficient in flotillin-1. The flotillin deficiency inhibited strongly the TRIF-dependent endosomal signaling of LPS-activated TLR4, and to a lower extent also the MyD88-dependent one, without affecting the cellular level of TLR4. The flotillin depletion also inhibited the pro-inflammatory activity of TLR2/TLR1 and TLR2/TLR6 but not TLR3. In agreement with those effects, the depletion of flotillins down-regulated the CD14 mRNA level and the cellular content of CD14 protein, and also inhibited constitutive CD14 endocytosis thereby facilitating its shedding. Ultimately, the cell-surface level of CD14 was markedly diminished. Concomitantly, CD14 recycling was enhanced via EEA1-positive early endosomes and golgin-97-positive trans-Golgi network, likely to compensate for the depletion of the cell-surface CD14. We propose that the paucity of surface CD14 is the reason for the down-regulated signaling of TLR4 and the other TLRs depending on CD14 for ligand binding.


Subject(s)
Lipopolysaccharide Receptors , Lipopolysaccharides , Membrane Proteins , Protein Transport , Signal Transduction , Toll-Like Receptor 4 , Lipopolysaccharide Receptors/metabolism , Toll-Like Receptor 4/metabolism , Lipopolysaccharides/pharmacology , Membrane Proteins/metabolism , Membrane Proteins/genetics , Signal Transduction/drug effects , Mice , Animals , RAW 264.7 Cells , Endocytosis/drug effects , Macrophages/metabolism , Adaptor Proteins, Vesicular Transport/metabolism , Adaptor Proteins, Vesicular Transport/genetics , RNA, Small Interfering/metabolism , Endosomes/metabolism
3.
J Lipid Res ; 65(1): 100480, 2024 Jan.
Article in English | MEDLINE | ID: mdl-38008259

ABSTRACT

Diacylglycerol kinase-ε (DGKε) catalyzes phosphorylation of diacylglycerol to phosphatidic acid with a unique specificity toward 1-stearoyl-2-arachidonoyl-sn-glycerol, which is a backbone of phosphatidylinositol (PI). Owing to this specificity, DGKε is involved in the PI cycle maintaining the cellular level of phosphorylated PI derivatives of signaling activity and was also found crucial for lipid metabolism. DGKε dysfunction is linked with the development of atypical hemolytic uremic syndrome (aHUS) and possibly other human diseases. Despite the DGKε significance, data on its regulation by cotranslational and/or post-translational modifications are scarce. Here, we report that DGKε is S-palmitoylated at Cys38/40 (mouse/human DGKε) located in the cytoplasmic end of its N-terminal putative transmembrane fragment. The S-palmitoylation of DGKε was revealed by metabolic labeling of cells with a palmitic acid analogue followed by click chemistry and with acyl-biotin and acyl-polyethylene glycol exchange assays. The S-acyltransferases zDHHC7 (zinc finger DHHC domain containing) and zDHHC17 and the zDHHC6/16 tandem were found to catalyze DGKε S-palmitoylation, which also increased the DGKε abundance. Mouse DGKε-Myc ectopically expressed in human embryonic kidney 293 cells localized to the endoplasmic reticulum where zDHHC6/16 reside and in small amounts also to the Golgi apparatus where zDHHC7 and zDHHC17 are present. The Cys38Ala substitution upregulated, whereas hyperpalmitoylation of wild-type DGKε reduced the kinase activity, indicating an inhibitory effect of the Cys38 S-palmitoylation. In addition, the substitution of neighboring Pro31 with Ala also diminished the activity of DGKε. Taken together, our data indicate that S-palmitoylation can fine-tune DGKε activity in distinct cellular compartments, possibly by affecting the distance between the kinase and its substrate in a membrane.


Subject(s)
Cysteine , Diacylglycerol Kinase , Mice , Humans , Animals , Diacylglycerol Kinase/genetics , Diacylglycerol Kinase/metabolism , Signal Transduction , Cytosol/metabolism , Lipid Metabolism
4.
Traffic ; 23(6): 310-330, 2022 06.
Article in English | MEDLINE | ID: mdl-35411668

ABSTRACT

TLR4 is activated by the bacterial endotoxin lipopolysaccharide (LPS) and triggers two proinflammatory signaling cascades: a MyD88-dependent one in the plasma membrane, and the following TRIF-dependent one in endosomes. An inadequate inflammatory reaction can be detrimental for the organism by leading to sepsis. Therefore, novel approaches to therapeutic modulation of TLR4 signaling are being sought after. The TLR4 activity is tightly connected with the presence of CD14, a GPI-anchored protein that transfers LPS monomers to the receptor and controls its endocytosis. In this study we focused on CD14 trafficking as a still poorly understood factor affecting TLR4 activity. Two independent assays were used to show that after endocytosis CD14 can recycle back to the plasma membrane in both unstimulated and stimulated cells. This route of CD14 trafficking can be controlled by sorting nexins (SNX) 1, 2 and 6, and is important for maintaining the surface level and the total level of CD14, but can also affect the amount of TLR4. Silencing of these SNXs attenuated especially the CD14-dependent endosomal signaling of TLR4, making them a new target for therapeutic regulation of the inflammatory response of macrophages to LPS.


Subject(s)
Lipopolysaccharides , Toll-Like Receptor 4 , Animals , Endocytosis , Lipopolysaccharide Receptors/metabolism , Lipopolysaccharides/pharmacology , Macrophages/metabolism , Mice , Signal Transduction , Toll-Like Receptor 4/metabolism
5.
Int J Mol Sci ; 22(23)2021 Dec 03.
Article in English | MEDLINE | ID: mdl-34884899

ABSTRACT

Palmitic acid (C16:0) is the most abundant saturated fatty acid in animals serving as a substrate in synthesis and ß-oxidation of other lipids, and in the modification of proteins called palmitoylation. The influence of dietary palmitic acid on protein S-palmitoylation remains largely unknown. In this study we performed high-throughput proteomic analyses of a membrane-enriched fraction of murine liver to examine the influence of a palm oil-rich diet (HPD) on S-palmitoylation of proteins. HPD feeding for 4 weeks led to an accumulation of C16:0 and C18:1 fatty acids in livers which disappeared after 12-week feeding, in contrast to an accumulation of C16:0 in peritoneal macrophages. Parallel proteomic studies revealed that HPD feeding induced a sequence of changes of the level and/or S-palmitoylation of diverse liver proteins involved in fatty acid, cholesterol and amino acid metabolism, hemostasis, and neutrophil degranulation. The HPD diet did not lead to liver damage, however, it caused progressing obesity, hypercholesterolemia and hyperglycemia. We conclude that the relatively mild negative impact of such diet on liver functioning can be attributed to a lower bioavailability of palm oil-derived C16:0 vs. that of C18:1 and the efficiency of mechanisms preventing liver injury, possibly including dynamic protein S-palmitoylation.


Subject(s)
Liver/metabolism , Palm Oil/administration & dosage , Palmitic Acid/chemistry , Proteomics/methods , Soybean Oil/administration & dosage , Amino Acids/metabolism , Animals , Dietary Supplements , Fatty Acids/analysis , Homeostasis , Liver/drug effects , Macrophages, Peritoneal/chemistry , Male , Mass Spectrometry , Mice , Palm Oil/chemistry , Palm Oil/pharmacology , Soybean Oil/pharmacology
6.
Cell Mol Life Sci ; 78(4): 1233-1261, 2021 Feb.
Article in English | MEDLINE | ID: mdl-33057840

ABSTRACT

Toll-like receptor (TLR) 4 belongs to the TLR family of receptors inducing pro-inflammatory responses to invading pathogens. TLR4 is activated by lipopolysaccharide (LPS, endotoxin) of Gram-negative bacteria and sequentially triggers two signaling cascades: the first one involving TIRAP and MyD88 adaptor proteins is induced in the plasma membrane, whereas the second engaging adaptor proteins TRAM and TRIF begins in early endosomes after endocytosis of the receptor. The LPS-induced internalization of TLR4 and hence also the activation of the TRIF-dependent pathway is governed by a GPI-anchored protein, CD14. The endocytosis of TLR4 terminates the MyD88-dependent signaling, while the following endosome maturation and lysosomal degradation of TLR4 determine the duration and magnitude of the TRIF-dependent one. Alternatively, TLR4 may return to the plasma membrane, which process is still poorly understood. Therefore, the course of the LPS-induced pro-inflammatory responses depends strictly on the rates of TLR4 endocytosis and trafficking through the endo-lysosomal compartment. Notably, prolonged activation of TLR4 is linked with several hereditary human diseases, neurodegeneration and also with autoimmune diseases and cancer. Recent studies have provided ample data on the role of diverse proteins regulating the functions of early, late, and recycling endosomes in the TLR4-induced inflammation caused by LPS or phagocytosis of E. coli. In this review, we focus on the mechanisms of the internalization and intracellular trafficking of TLR4 and CD14, and also of LPS, in immune cells and discuss how dysregulation of the endo-lysosomal compartment contributes to the development of diverse human diseases.


Subject(s)
Adaptor Proteins, Vesicular Transport/genetics , Inflammation/genetics , Lipopolysaccharide Receptors/genetics , Toll-Like Receptor 4/genetics , Adaptor Proteins, Signal Transducing/genetics , Humans , Inflammation/chemically induced , Inflammation/pathology , Lipopolysaccharides/toxicity , Membrane Glycoproteins/genetics , Myeloid Differentiation Factor 88/genetics , Phagocytosis/genetics , Receptors, Interleukin-1/genetics
7.
Int J Mol Sci ; 21(7)2020 Mar 26.
Article in English | MEDLINE | ID: mdl-32225034

ABSTRACT

Flotillin-1 and flotillin-2 are ubiquitously expressed, membrane-associated proteins involved in multifarious cellular events from cell signaling, endocytosis, and protein trafficking to gene expression. They also contribute to oncogenic signaling. Flotillins bind the cytosolic leaflet of the plasma membrane and endomembranes and, upon hetero-oligomerization, serve as scaffolds facilitating the assembly of multiprotein complexes at the membrane-cytosol interface. Additional functions unique to flotillin-1 have been discovered recently. The membrane-binding of flotillins is regulated by S-palmitoylation and N-myristoylation, hydrophobic interactions involving specific regions of the polypeptide chain and, to some extent, also by their oligomerization. All these factors endow flotillins with an ability to associate with the sphingolipid/cholesterol-rich plasma membrane domains called rafts. In this review, we focus on the critical input of lipids to the regulation of the flotillin association with rafts and thereby to their functioning. In particular, we discuss how the recent developments in the field of protein S-palmitoylation have contributed to the understanding of flotillin1/2-mediated processes, including endocytosis, and of those dependent exclusively on flotillin-1. We also emphasize that flotillins affect directly or indirectly the cellular levels of lipids involved in diverse signaling cascades, including sphingosine-1-phosphate and PI(4,5)P2. The mutual relations between flotillins and distinct lipids are key to the regulation of their involvement in numerous cellular processes.


Subject(s)
Lipoylation , Membrane Proteins/metabolism , Signal Transduction , Animals , Endocytosis , Humans , Membrane Microdomains/metabolism , Phosphatidylinositol 4,5-Diphosphate/metabolism
8.
Article in English | MEDLINE | ID: mdl-31678513

ABSTRACT

Bacterial lipopolysaccharide (LPS) is recognized by CD14 protein and the Toll-like receptor (TLR)4/MD2 complex localized in the plasma membrane of immune cells. TLR4 triggers two signaling pathways engaging the MyD88 and TRIF adaptor proteins which lead to production of various pro-inflammatory cytokines. These processes are likely to be modulated by sphingomyelin, as the CD14 - TLR4 interaction takes place in plasma membrane rafts enriched in this lipid. To verify this assumption, we analyzed the influence of tricyclodecane-9-yl xanthogenate (D609), which was proven here to be an SMS inhibitor, and silencing of sphingomyelin synthase (SMS) 1 and/or SMS2 on LPS-induced signaling in macrophages. LPS up-regulated the expression and activity of SMS while exposure to D609 or silencing of SMS1 and SMS2 counteracted this action and led (except for SMS2 silencing) to a depletion of sphingomyelin in cells. Concomitantly, the MyD88- and TRIF-dependent signaling pathways of TLR4 were inhibited with the latter being especially sensitive to the reduction of the SMS1 and/or SMS2 activity. The D609 treatment and SMS1 and/or SMS2 depletion all reduced the level of CD14 protein in cells, which likely was an important determinant of the reduction of the LPS-induced pro-inflammatory responses.


Subject(s)
Signal Transduction/immunology , Sphingomyelins/metabolism , Toll-Like Receptor 4/metabolism , Transferases (Other Substituted Phosphate Groups)/metabolism , Adaptor Proteins, Vesicular Transport/metabolism , Animals , Bridged-Ring Compounds/pharmacology , Cell Line, Tumor , Cell Membrane/drug effects , Cell Membrane/immunology , Cell Membrane/metabolism , Down-Regulation/drug effects , Down-Regulation/immunology , Lipopolysaccharide Receptors/immunology , Lipopolysaccharide Receptors/metabolism , Lipopolysaccharides/immunology , Macrophages/drug effects , Macrophages/immunology , Macrophages/metabolism , Male , Mice , Norbornanes , Primary Cell Culture , RNA Interference , RNA, Small Interfering/metabolism , Signal Transduction/drug effects , Thiocarbamates , Thiones/pharmacology , Toll-Like Receptor 4/genetics , Transferases (Other Substituted Phosphate Groups)/antagonists & inhibitors , Transferases (Other Substituted Phosphate Groups)/genetics , Up-Regulation/drug effects , Up-Regulation/immunology
9.
J Leukoc Biol ; 106(6): 1285-1301, 2019 12.
Article in English | MEDLINE | ID: mdl-31335985

ABSTRACT

Bacterial LPS strongly induces pro-inflammatory responses of Mϕs after binding to CD14 protein and the TLR4/MD-2 receptor complex. The LPS-triggered signaling can be modulated by extracellular lysophosphatidic acid (LPA), which is of substantial importance for Mϕ functioning under specific pathophysiological conditions, such as atherosclerosis. The molecular mechanisms of the crosstalk between the LPS- and LPA-induced signaling, and the LPA receptors involved, are poorly known. In this report, we show that LPA strongly inhibits the LPS-induced TNF-α production at the mRNA and protein levels in primary Mϕs and Mϕ-like J774 cells. The decreased TNF-α production in LPA/LPS-stimulated cells is to high extent independent of NF-κB but is preceded by enhanced expression and secretion of the anti-inflammatory cytokine IL-10. The IL-10 elevation and TNF-α reduction are both abrogated upon depletion of the LPA5 and LPA6 receptors in J774 cells and can be linked with LPA-mediated activation of p38. We propose that the binding of LPA to LPA5 and LPA6 fine-tunes the LPS-induced inflammatory response by activating p38, and up-regulating IL-10 and down-regulating TNF-α production.


Subject(s)
Interleukin-10/biosynthesis , Lipopolysaccharides/immunology , Lysophospholipids/pharmacology , Macrophages/drug effects , Macrophages/physiology , Tumor Necrosis Factor-alpha/biosynthesis , Animals , Cytokines/biosynthesis , Gene Expression Regulation/drug effects , Gene Silencing , Interferon Regulatory Factors/metabolism , Macrophage Activation/genetics , Macrophage Activation/immunology , Mice , NF-kappa B/metabolism , Phosphorylation , Proto-Oncogene Proteins c-akt/metabolism , Signal Transduction/drug effects , Transcriptional Activation/drug effects , Transcriptional Activation/immunology , Tumor Necrosis Factor-alpha/genetics
10.
Postepy Biochem ; 64(3): 175-182, 2018 Oct 25.
Article in English | MEDLINE | ID: mdl-30656902

ABSTRACT

Lipopolysaccharide (LPS, endotoxin) is the component of the outer membrane of Gramnegative bacteria which upon infection induces the body's inflammatory reaction facilitating eradication of pathogens. However, exaggerated reactions to LPS can lead to potentially deadly sepsis while chronic, low-grade inflammation is linked with the development of several metabolic diseases, like type 2 diabetes. These processes are initiated by the binding of LPS to CD14 protein and the TLR4/MD2 receptor complex located in the plasma membrane of immune cells and also by the activation of a cytoplasmic multi-protein complex called the inflammasome. Recent studies have shown that lipids of the plasma membrane and endomembranes are important regulators of LPS-triggered signaling pathways. In this review we summarize those data emphasizing the role of phosphatidylinositols and modification of proteins by palmitoylation. Dysregulation of the lipid-dependent steps of the LPS-induced signaling can lead to excessive production of cytokines during sepsis and metabolic diseases linked with endotoxemia.


Subject(s)
Inflammation/chemically induced , Inflammation/metabolism , Lipopolysaccharides/pharmacology , Lipoylation/drug effects , Phosphatidylinositols/metabolism , Diabetes Mellitus, Type 2/metabolism , Endotoxemia/chemically induced , Endotoxemia/metabolism , Humans , Sepsis/chemically induced , Sepsis/metabolism , Signal Transduction/drug effects
11.
Mol Biol Cell ; 28(8): 1147-1159, 2017 Apr 15.
Article in English | MEDLINE | ID: mdl-28228554

ABSTRACT

Lipopolysaccharide (LPS) is the component of Gram-negative bacteria that activates Toll-like receptor 4 (TLR4) to trigger proinflammatory responses. We examined the involvement of Lyn tyrosine kinase in TLR4 signaling of macrophages, distinguishing its catalytic activity and intermolecular interactions. For this, a series of Lyn-GFP constructs bearing point mutations in particular domains of Lyn were overexpressed in RAW264 macrophage-like cells or murine peritoneal macrophages, and their influence on LPS-induced responses was analyzed. Overproduction of wild-type or constitutively active Lyn inhibited production of TNF-α and CCL5/RANTES cytokines and down-regulated the activity of NFκB and IRF3 transcription factors in RAW264 cells. The negative influence of Lyn was nullified by point mutations of Lyn catalytic domain or Src homology 2 (SH2) or SH3 domains or of the cysteine residue that undergoes LPS-induced palmitoylation. Depending on the cell type, overproduction of those mutant forms of Lyn could even up-regulate LPS-induced responses, and this effect was reproduced by silencing of endogenous Lyn expression. Simultaneously, the Lyn mutations blocked its LPS-induced accumulation in the raft fraction of RAW264 cells. These data indicate that palmitoylation, SH2- and SH3-mediated intermolecular interactions, and the catalytic activity of Lyn are required for its accumulation in rafts, thereby determining the negative regulation of TLR4 signaling.


Subject(s)
Membrane Microdomains/enzymology , src-Family Kinases/genetics , src-Family Kinases/metabolism , Animals , Cell Line , Chemokine CCL5/metabolism , Green Fluorescent Proteins , Interferon Regulatory Factor-3/metabolism , Lipopolysaccharides/pharmacology , Macrophages/metabolism , Macrophages, Peritoneal/metabolism , Male , Membrane Microdomains/metabolism , Mice , Mice, Inbred C57BL , NF-kappa B/metabolism , Phosphorylation , Protein-Tyrosine Kinases/metabolism , Signal Transduction , Toll-Like Receptor 4/genetics , Toll-Like Receptor 4/metabolism , Tumor Necrosis Factor-alpha/metabolism
12.
Front Immunol ; 8: 2003, 2017.
Article in English | MEDLINE | ID: mdl-29403483

ABSTRACT

S-palmitoylation is a reversible, enzymatic posttranslational modification of proteins in which palmitoyl chain is attached to a cysteine residue via a thioester linkage. S-palmitoylation determines the functioning of proteins by affecting their association with membranes, compartmentalization in membrane domains, trafficking, and stability. In this review, we focus on S-palmitoylation of proteins, which are crucial for the interactions of pathogenic bacteria and viruses with the host. We discuss the role of palmitoylated proteins in the invasion of host cells by bacteria and viruses, and those involved in the host responses to the infection. We highlight recent data on protein S-palmitoylation in pathogens and their hosts obtained owing to the development of methods based on click chemistry and acyl-biotin exchange allowing proteomic analysis of protein lipidation. The role of the palmitoyl moiety present in bacterial lipopolysaccharide and lipoproteins, contributing to infectivity and affecting recognition of bacteria by innate immune receptors, is also discussed.

13.
Int J Biochem Cell Biol ; 83: 15-26, 2017 02.
Article in English | MEDLINE | ID: mdl-27939812

ABSTRACT

Toll-like receptor 4 (TLR4) is the receptor for bacterial lipopolysaccharide (LPS) triggering production of pro-inflammatory cytokines which help eradicate the bacteria but could also be harmful when overproduced. The signaling activity of TLR4 is modulated by cholesterol level in cellular membranes, which in turn is affected by bis(monoacylglycero)phosphate (BMP), a phospholipid enriched in late endosomes. We found that exogenously added BMP isomers become incorporated into the plasma membrane and intracellular vesicles of macrophages and strongly reduced LPS-stimulated production of a chemokine RANTES, which was correlated with inhibition of interferon regulatory factor 3 (IRF3) controlling Rantes expression. To investigate the mechanism underlying the influence of BMP on TLR4 signaling we applied Laurdan and studied the impact of BMP incorporation on lipid packing, a measure for membrane order. Enrichment of model and cellular membranes with BMP significantly reduced their order and the reduction was maintained during stimulation of cells with LPS. This effect of BMP was abolished by enrichment of macrophages with cholesterol. In parallel, the inhibitory effect of BMP exerted on the TLR4-dependent phosphorylation of IRF3 was also reversed. Taken together our results indicate that BMP reduces the order of macrophage membranes which contributes to the inhibition of TLR4-dependent RANTES production.


Subject(s)
Chemokine CCL5/biosynthesis , Lysophospholipids/metabolism , Lysophospholipids/pharmacology , Macrophages/drug effects , Macrophages/metabolism , Monoglycerides/metabolism , Monoglycerides/pharmacology , Toll-Like Receptor 4/antagonists & inhibitors , Animals , Atherosclerosis/etiology , Atherosclerosis/metabolism , Atherosclerosis/prevention & control , Cell Membrane/metabolism , Cells, Cultured , Cholesterol/metabolism , Interferon Regulatory Factor-3/metabolism , Lipopolysaccharides/toxicity , Mice , Mice, Inbred C57BL , Models, Biological , RAW 264.7 Cells , Signal Transduction/drug effects , Toll-Like Receptor 4/metabolism
14.
J Leukoc Biol ; 100(6): 1363-1373, 2016 12.
Article in English | MEDLINE | ID: mdl-27418354

ABSTRACT

LPS binds sequentially to CD14 and TLR4/MD2 receptor triggering production of proinflammatory mediators. The LPS-induced signaling is controlled by a plasma membrane lipid PI(4,5)P2 and its derivatives. Here, we show that stimulation of murine peritoneal macrophages with LPS induces biphasic accumulation of PI(4,5)P2 with peaks at 10 and 60-90 min that were still seen after silencing of TLR4 expression. In contrast, the PI(4,5)P2 elevation was abrogated when CD14 was removed from the cell surface. To assess the contribution of CD14 and TLR4 to the LPS-induced PI(4,5)P2 changes, we used HEK293 transfectants expressing various amounts of CD14 and TLR4. In cells with a low content of CD14 and high of TLR4, no accumulation of PI(4,5)P2 occurred. With an increasing amount of CD14 and concomitant decrease of TLR4, 2 peaks of PI(4,5)P2 accumulation appeared, eventually approaching those found in LPS-stimulated cells expressing CD14 alone. Mutation of the signaling domain of TLR4 let us conclude that the receptor activity can modulate PI(4,5)P2 accumulation in cells when expressed in high amounts compared with CD14. Among the factors limiting PI(4,5)P2 accumulation are its hydrolysis, phosphorylation, and availability of its precursor, PI(4)P. Inhibition of PLC and PI3K or overexpression of PI4K IIα that produces PI(4)P promoted PI(4,5)P2 elevation in LPS-stimulated cells. The elevation of PI(4,5)P2 was dispensable for TLR4 signaling yet enhanced its magnitude. Taken together, these data suggest that LPS-induced accumulation of PI(4,5)P2 that maximizes TLR4 signaling is controlled by CD14, whereas TLR4 can fine tune the process by affecting the PI(4,5)P2 turnover.


Subject(s)
Lipopolysaccharide Receptors/physiology , Phosphatidylinositol 4,5-Diphosphate/biosynthesis , Toll-Like Receptor 4/physiology , Animals , Genes, Reporter , HEK293 Cells , Humans , Lipopolysaccharides/pharmacology , Lipoylation , Lymphocyte Activation , Macrophage Activation , Macrophages, Peritoneal/drug effects , Macrophages, Peritoneal/metabolism , Male , Mice , Mice, Inbred C57BL , Minor Histocompatibility Antigens/metabolism , NF-kappa B/metabolism , Phosphotransferases (Alcohol Group Acceptor)/metabolism , Protein Processing, Post-Translational , RNA Interference , Specific Pathogen-Free Organisms , Toll-Like Receptor 4/antagonists & inhibitors
15.
Biosci Rep ; 36(3)2016 07.
Article in English | MEDLINE | ID: mdl-27129297

ABSTRACT

Cyclic phosphatidic acids (cPAs) are naturally occurring, very active signalling molecules, which are involved in several pathological states, such as cancer, diabetes or obesity. As molecules of highly lipidic character found in the circulatory system, cPAs are bound and transported by the main extracellular lipid binding protein-serum albumin. Here, we present the detailed interactions between human serum albumin (HSA) and equine serum albumin (ESA) with a derivative of cPA, 1-O-myristoyl-sn-glycerol-2,3-cyclic phosphorodithioate (Myr-2S-cPA). Initial selection of the ligand used for the structural study was made by the analysis of the therapeutically promising properties of the sulfur containing analogues of cPA in respect to the unmodified lysophospholipids (LPLs). Substitution of one or two non-bridging oxygen atoms in the phosphate group with one or two sulfur atoms increases the cytotoxic effect of cPAs up to 60% on the human prostate cancer (PC) cells. Myr-2S-cPA reduces cancer cell viability in a dose-dependent manner, with IC50 value of 29.0 µM after 24 h incubation, which is almost 30% lower than IC50 of single substituted phosphorothioate cPA. Although, the structural homology between HSA and ESA is big, their crystal complexes with Myr-2S-cPA demonstrate significantly different mode of binding of this LPL analogue. HSA binds three molecules of Myr-2S-cPA, whereas ESA only one. Moreover, none of the identified Myr-2S-cPA binding sites overlap in both albumins.


Subject(s)
Lysophospholipids/chemistry , Phosphatidic Acids/chemistry , Prostatic Neoplasms/metabolism , Serum Albumin/chemistry , Animals , Binding Sites , Cell Line, Tumor , Cell Survival/genetics , Crystallography, X-Ray , Horses , Humans , Lysophospholipids/metabolism , Male , Phosphatidic Acids/metabolism , Prostatic Neoplasms/pathology , Protein Binding , Serum Albumin/metabolism , Species Specificity
16.
Curr Top Med Chem ; 15(23): 2395-405, 2015.
Article in English | MEDLINE | ID: mdl-26088355

ABSTRACT

Nutrient-induced increase in intracellular Ca(2+) concentration ([Ca(2+)]i) is one of the key mechanisms responsible for insulin release from pancreatic islet ß cells. Lysophosphatidylcholine (LPC) was demonstrated to induce insulin secretion from ß cells, activate glucose uptake and effectively lower blood glucose levels in mouse models of type 1 and 2 diabetes mellitus. The article hereby presents the results of a characterization of 2-OMe-LPC sulfur analogues with defined acyl residues in terms of their effect on intracellular Ca(2+) concentration and cellular membrane integrity in the murine ßTC-3 cell model. Active LPC series that could induce calcium flux in ßTC-3 cell model include unmodified LPC 12:0, 14:0, 16:0, and 18:0 as well as phosphorothioate analogues of LPC 12:0, 14:0 and 16:0. However, in the case of species bearing mirystoyl and palmitoyl residues [Ca(2+)]i was associated with membrane permeabilization as demonstrated by propidium iodide incorporation and lactate dehydrogenase release. LPC 12:0 (both unmodified and a sulfurcontaining counterpart) and unmodified LPC 18:0 did not demonstrate membrane disruption but acted as calcium inducers. Interestingly, no stimulation of calcium flux or membrane disruption was observed in the case of LPC analogues with two sulfur atoms introduced into a phosphate group. Experiments with nitrendipine and NiCl2 blocking voltage-dependent calcium channels and the general calcium influx, respectively, revealed remarkably that the compounds studied were involved in different signaling mechanisms while administered to the cell culture, which is clearly related to their chemical structure, both acyl chain and modification dependently.


Subject(s)
Antineoplastic Agents/chemistry , Insulin-Secreting Cells/drug effects , Insulin/metabolism , Lysophosphatidylcholines/chemistry , Sulfur Compounds/chemistry , Animals , Antineoplastic Agents/pharmacology , Calcium/metabolism , Calcium Channels/metabolism , Cell Culture Techniques , Cell Line, Tumor , Cell Proliferation/drug effects , Cell Survival/drug effects , Insulin Secretion , Insulin-Secreting Cells/metabolism , Lysophosphatidylcholines/pharmacology , Membrane Fluidity/drug effects , Mice , Molecular Structure , Sulfur Compounds/pharmacology
17.
Bioessays ; 37(7): 789-801, 2015 Jul.
Article in English | MEDLINE | ID: mdl-25966354

ABSTRACT

You are what you eat - this well-known phrase properly describes the phenomenon of the effects of diet on acute and chronic inflammation. Several lipids and lipophilic compounds that are delivered with food or are produced in situ in pathological conditions exert immunomodulatory activity due to their interactions with the plasma membrane. This group of compounds includes cholesterol and its oxidized derivatives, fatty acids, α-tocopherol, and polyphenols. Despite their structural heterogeneity, all these compounds ultimately induce changes in plasma membrane architecture and fluidity. By doing this, they modulate the dynamics of plasma membrane receptors, such as TLR4. This receptor is activated by lipopolysaccharide, triggering acute inflammation during bacterial infection, which often leads to sepsis and is linked with diverse chronic inflammatory diseases. In this review, we discuss how the impact on plasma membrane properties contributes to the immunomodulatory activity of dietary compounds, pointing to the therapeutic potential of some of them. Also watch the Video Abstract.


Subject(s)
Cell Membrane/metabolism , Dietary Fats/metabolism , Signal Transduction , Animals , Antioxidants/metabolism , Diet , Humans , Inflammation Mediators/metabolism , Toll-Like Receptor 4/physiology
18.
Neurol Neurochir Pol ; 49(1): 65-9, 2015.
Article in English | MEDLINE | ID: mdl-25666777

ABSTRACT

The optic tract section at the optic chiasm is expected to disturb the suprachiasmatic nucleus (SCN) rhythm, circadian rhythm and melatonin secretion rhythms in humans, although detailed studies have never been conducted. The aim of this paper was to describe melatonin and cortisol profiles in patients with a pituitary tumor exerting optic chiasm compression. Six patients with pituitary tumors of different size, four of whom had significant optic chiasm compression, were examined. In each brain, MRI, an ophthalmological examination including the vision field and laboratory tests were performed. Melatonin and cortisol concentrations were measured at 22:00 h, 02:00 h, 06:00 h, and 10:00 h in patients lying in a dark, isolated room. One of the four cases with significant optic chiasm compression presented a flattened melatonin rhythm. The melatonin rhythm was also disturbed in one patient without optic chiasm compression. Larger tumors may play a role in the destruction of neurons connecting the retina with the suprachiasmatic nucleus (SCN) and breaking of basic way for inhibiting effect to the SCN from the retina.


Subject(s)
Circadian Rhythm/physiology , Hydrocortisone/blood , Melatonin/blood , Pituitary Neoplasms/blood , Adult , Female , Humans , Male , Middle Aged , Optic Chiasm/pathology , Optic Chiasm/physiopathology
19.
Pol Arch Med Wewn ; 122(7-8): 361-6, 2012.
Article in English | MEDLINE | ID: mdl-22759978

ABSTRACT

INTRODUCTION:  Streptococcus pneumoniae (S. pneumoniae) is one of the most common bacterial pathogens in community­acquired pneumonia. However, nosocomial pneumococcal infections are more and more widely observed. OBJECTIVES:  The aim of the study was to analyze nosocomial outbreak in one of the Polish hospitals and to characterize the causative isolates. PATIENTS AND METHODS:  Within 10 days, in 6 patients receiving an antimicrobial therapy due to a primary disease, pneumococcal infections of the lower respiratory tract were identified. All patients, except 1 patient with asthma, were hospitalized due to exacerbation of chronic obstructive pulmonary disease (COPD). The isolates were identified by standard methods. The serotypes of S. pneumoniae were determined by the Pneumotest­Latex kit. The relatedness among isolates was evaluated by restriction fragment length polymorphism followed by pulsed­field gel electrophoresis (RFLP­PFGE). Multilocus sequence typing (MLST) was performed for a representative isolate. RESULTS:  The outbreak was suspected when characteristic multidrug­resistant pneumococci were isolated from patients of a single ward. The outbreak was confirmed by molecular typing techniques. All isolates belonged to serotype 14 and shared the RFLP­PFGE pattern. MLST for a representative isolate revealed that it was a member of the epidemic Spain9V­ST156 clonal complex. CONCLUSIONS:  Timely implementation of infection control measures enabled to eradicate the outbreak. Pneumococcal conjugate vaccine, recently registered for use in adult populations, may have a considerable effect on limiting pneumococcal disease­associated morbidity and mortality. It is especially important for patients with COPD, a disease entity that constitutes a risk factor for the acquisition of multidrug­resistant pneumococci. 


Subject(s)
Bacterial Proteins/genetics , Cross Infection/microbiology , Peptide Synthases/genetics , Pneumococcal Infections/microbiology , Respiratory Tract Infections/microbiology , Streptococcus pneumoniae/classification , Acute Disease , Adult , Aged , Aged, 80 and over , Disease Outbreaks/statistics & numerical data , Female , Humans , Middle Aged , Molecular Sequence Data , Peptidyl Transferases/genetics , Pneumococcal Infections/epidemiology , Polymorphism, Genetic , Polymorphism, Restriction Fragment Length , Respiratory Tract Infections/epidemiology , Serotyping , Species Specificity , Streptococcus pneumoniae/isolation & purification
20.
Pneumonol Alergol Pol ; 80(4): 308-16, 2012.
Article in Polish | MEDLINE | ID: mdl-22714074

ABSTRACT

INTRODUCTION: In long term oxygen therapy (LTOT) two oxygen sources are used, i.e. the stationary oxygen concentrator (OC) and portable liquid oxygen (LO). Polish NHS reimburses stationary oxygen sources only. The aim of this study was to compare the effect of change from OC into LO in patients treated using LTOT. MATERIAL AND METHODS: The study involved 30 patients qualified to LTOT. The degree of dyspnoea intensity, (MRC, Borg scale), exercise tolerance (6MWT), fitness, daily use of oxygen therapy, red blood count, lung function, number of exacerbations as well as health related quality of life (SGRQ) were assessed before introduction of LTOT, after 6 months of oxygen therapy using OC and after 6 months from change into LO. RESULTS: During first 6 months RBC decreased from 5.4 to 5.1 (p < 0.0001), HTC from 50.1% to 47.8% (p < 0.0001), 6MWD increased from 337.7 to 378.7 m (p < 0.0001), SGRQ score improved from 72.1 points to 64.4 points (p < 0.0001). Treatment with LO resulted in further improvement in studied parameters: RBC decreased from 5.1 to 4.8 (p < 0.0001), HTC from 47.8% to 44.3% (p < 0.0001), 6MWD increased from 378.7 m to 413 m (p < 0.0001), SGRQ score improved from 64.4 points to 54.9 points (p < 0.0001). Significant increase in daily oxygen breathing hours from 13.7 to 18.9 (p < 0.0001) was also observed. CONCLUSIONS: Use of liquid oxygen enables oxygen therapy at home and during ambulation and increases oxygen breathing hours, thus improving red blood count, exercise capacity and health related quality of life.


Subject(s)
Ambulatory Care/statistics & numerical data , Oxygen Inhalation Therapy/methods , Oxygen/administration & dosage , Pulmonary Disease, Chronic Obstructive/therapy , Quality of Life , Severity of Illness Index , Aged , Equipment Design , Exercise Tolerance , Female , Home Care Services/statistics & numerical data , Humans , Male , Middle Aged , Patient Compliance/statistics & numerical data , Respiratory Function Tests , Treatment Outcome , Walking
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