Browse
Submit Data
Databases
API
Help

Dataset Information

18 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Erythrocytes efficiently utilize exogenous sphingosines for S1P synthesis and export via Mfsd2b.

ABSTRACT: Sphingosine-1-phosphate (S1P) is a potent lipid mediator that exerts its activity via activation of five different G protein-coupled receptors, designated as S1P1-5. This potent lipid mediator is synthesized from the sphingosine precursor by two sphingosine kinases (SphK1 and 2) and must be exported to exert extracellular signaling functions. We recently identified Mfsd2b as the S1P transporter in the hematopoietic system. However, the sources of sphingosine for S1P synthesis and the transport mechanism of Mfsd2b in erythrocytes remain to be determined. Here, we show that erythrocytes efficiently take up exogenous sphingosine and that a de novo synthesis pathway in part provides sphingosines to erythrocytes. The uptake of sphingosine in erythrocytes is facilitated by the activity of SphK1. By converting sphingosine into S1P, SphK1 indirectly increases the influx of sphingosine, a process that is irreversible in erythrocytes. Our results explain for the abnormally high amount of sphingosine accumulation in Mfsd2b knockout erythrocytes. Furthermore, we show that Mfsd2b utilizes a proton gradient to facilitate the release of S1P. The negatively charged residues D95 and T157 are essential for Mfsd2b transport activity. Of interest, we also discovered an S1P analog that inhibits S1P export from erythrocytes, providing evidence that sphingosine analogs can be used to inhibit S1P export by Mfsd2b. Collectively, our results highlight that erythrocytes are efficient in sphingosine uptake for S1P production and the release of S1P is dependent on Mfsd2b functions.

SUBMITTER: Nguyen TQ

PROVIDER: S-EPMC7948482 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Identification of mutant firefly luciferases that efficiently utilize aminoluciferins.

Project description:Firefly luciferase-catalyzed light emission from D-luciferin is widely used as a reporter of gene expression and enzymatic activity both in vitro and in vivo. Despite the power of bioluminescence for imaging and drug discovery, light emission from firefly luciferase is fundamentally limited by the physical properties of the D-luciferin substrate. We and others have synthesized aminoluciferin analogs that exhibit light emission at longer wavelengths than D-luciferin and have increased affinity for luciferase. However, although these substrates can emit an intense initial burst of light that approaches that of D-luciferin, this is followed by much lower levels of sustained light output. Here we describe the creation of mutant luciferases that yield improved sustained light emission with aminoluciferins in both lysed and live mammalian cells, allowing the use of aminoluciferins for cell-based bioluminescence experiments.

| S-EPMC3273327 | biostudies-literature

Exogenous S1P Exposure Potentiates Ischemic Stroke Damage That Is Reduced Possibly by Inhibiting S1P Receptor Signaling.

Project description:Initial and recurrent stroke produces central nervous system (CNS) damage, involving neuroinflammation. Receptor-mediated S1P signaling can influence neuroinflammation and has been implicated in cerebral ischemia through effects on the immune system. However, S1P-mediated events also occur within the brain itself where its roles during stroke have been less well studied. Here we investigated the involvement of S1P signaling in initial and recurrent stroke by using a transient middle cerebral artery occlusion/reperfusion (M/R) model combined with analyses of S1P signaling. Gene expression for S1P receptors and involved enzymes was altered during M/R, supporting changes in S1P signaling. Direct S1P microinjection into the normal CNS induced neuroglial activation, implicating S1P-initiated neuroinflammatory responses that resembled CNS changes seen during initial M/R challenge. Moreover, S1P microinjection combined with M/R potentiated brain damage, approximating a model for recurrent stroke dependent on S1P and suggesting that reduction in S1P signaling could ameliorate stroke damage. Delivery of FTY720 that removes S1P signaling with chronic exposure reduced damage in both initial and S1P-potentiated M/R-challenged brain, while reducing stroke markers like TNF-?. These results implicate direct S1P CNS signaling in the etiology of initial and recurrent stroke that can be therapeutically accessed by S1P modulators acting within the brain.

| S-EPMC4630407 | biostudies-literature

Plasmodium falciparum-infected erythrocytes utilize a synthetic truncated ceramide precursor for synthesis and secretion of truncated sphingomyelin.

Project description:Plasmodium falciparum is an intracellular parasite of human erythrocytes. Parasite development is accompanied by an increase of the phospholipid content of the infected erythrocyte, but it results in a selective decrease of sphingomyelin. We have studied sphingomyelin biosynthesis in infected erythrocytes using as substrate a synthetic radiolabelled ceramide precursor, truncated in both hydrophobic chains. Lysates of infected, unlike those of non-infected, erythrocytes contained sphingomyelin synthase activity, which therefore is of parasite origin. The enzyme activity was associated with a membrane fraction. In contrast to mammalian cells, the parasite did not synthesize detectable levels of glycosphingolipids. In intact infected erythrocytes the ceramide precursor was converted into a correspondingly truncated soluble sphingomyelin which was released into the medium at 37 degrees C. Release of truncated sphingomyelin was inhibited by low temperature (15 degrees C) but not by the fungal metabolite brefeldin A which, however, arrests protein export from the parasite. While membranes of mammalian cells, including the plasma membrane of non-infected erythrocytes, are impermeable to truncated sphingomyelin, the membrane of infected erythrocytes allowed passage of the molecule in both directions. The results obtained with the unicellular eukaryote used here as an experimental model are discussed in comparison with sphingomyelin synthesis and transport in mammalian cells.

| S-EPMC1136881 | biostudies-other

Extracellular export of sphingosine kinase-1a contributes to the vascular S1P gradient.

Project description:Sphingosine 1-phosphate (S1P), produced by Sphks (sphingosine kinases), is a multifunctional lipid mediator that regulates immune cell trafficking and vascular development. Mammals maintain a large concentration gradient of S1P between vascular and extravascular compartments. Mechanisms by which S1P is released from cells and concentrated in the plasma are poorly understood. We recently demonstrated [Ancellin, Colmont, Su, Li, Mittereder, Chae, Stefansson, Liau and Hla (2002) J. Biol. Chem. 277, 6667-6675] that Sphk1 activity is constitutively secreted by vascular endothelial cells. In the present study, we show that among the five Sphk isoforms expressed in endothelial cells, the Sphk-1a isoform is selectively secreted in HEK-293 cells (human embryonic kidney cells) and human umbilical-vein endothelial cells. In sharp contrast, Sphk2 is not secreted. The exported Sphk-1a isoform is enzymatically active and produced sufficient S1P to induce S1P receptor internalization. Wild-type mouse plasma contains significant Sphk activity (179 pmol x min(-1) x g(-1)). In contrast, Sphk1-/- mouse plasma has undetectable Sphk activity and approx. 65% reduction in S1P levels. Moreover, human plasma contains enzymatically active Sphk1 (46 pmol x min(-1) x g(-1)). These results suggest that export of Sphk-1a occurs under physiological conditions and may contribute to the establishment of the vascular S1P gradient.

| S-EPMC1533315 | biostudies-literature

Engineering a d-lactate dehydrogenase that can super-efficiently utilize NADPH and NADH as cofactors.

Project description:Engineering the cofactor specificity of a natural enzyme often results in a significant decrease in its activity on original cofactor. Here we report that a NADH-dependent dehydrogenase (d-LDH) from Lactobacillus delbrueckii 11842 can be rationally engineered to efficiently use both NADH and NADPH as cofactors. Point mutations on three amino acids (D176S, I177R, F178T) predicted by computational analysis resulted in a modified enzyme designated as d-LDH*. The Kcat/Km of the purified d-LDH* on NADPH increased approximately 184-fold while the Kcat/Km on NADH also significantly increased, showing for the first time that a rationally engineered d-LDH could exhibit comparable activity on both NADPH and NADH. Further kinetic analysis revealed that the enhanced affinity with NADH or NADPH and the significant increased Kcat of d-LDH* resulted in the significant increase of d-LDH* activity on both NADPH and NADH. This study thus demonstrated that the cofactor specificity of dehydrogenase can be broadened by using targeted engineering approach, and the engineered enzyme can efficiently function in NADH-rich, or NADPH-rich, or NADH and NADPH-rich environment.

| S-EPMC4842997 | biostudies-literature

Apobec 3G efficiently reduces infectivity of the human exogenous gammaretrovirus XMRV.

Project description:BackgroundThe human exogenous gammaretrovirus XMRV is thought to be implicated in prostate cancer and chronic fatigue syndrome. Besides pressing epidemiologic questions, the elucidation of the tissue and cell tropism of the virus, as well as its sensitivity to retroviral restriction factors is of fundamental importance. The Apobec3 (A3) proteins, a family of cytidine deaminases, are one important group of host proteins that control primary infection and efficient viral spread.Methodology/principal findingsHere we demonstrate that XMRV is resistant to human Apobec 3B, 3C and 3F, while being highly susceptible to the human A3G protein, a factor which is known to confer antiviral activity against most retroviruses. We show that XMRV as well as MoMLV virions package Apobec proteins independent of their specific restriction activity. hA3G was found to be a potent inhibitor of XMRV as well as of MoMLV infectivity. In contrast to MoMLV, XMRV infection can also be partially reduced by low concentrations of mA3. Interestingly, established prostate cancer cell lines, which are highly susceptible to XMRV infection, do not or only weakly express hA3G.ConclusionsOur findings confirm and extend recently published data that show restriction of XMRV infection by hA3G. The results will be of value to explore which cells are infected with XMRV and efficiently support viral spread in vivo. Furthermore, the observation that XMRV infection can be reduced by mA3 is of interest with regard to the current natural reservoir of XMRV infection.

| S-EPMC2909211 | biostudies-literature

S1P lyase inhibition protects against sepsis by promoting disease tolerance via the S1P/S1PR3 axis.

Project description:BackgroundOne-third of all deaths in hospitals are caused by sepsis. Despite its demonstrated prevalence and high case fatality rate, antibiotics remain the only target-oriented treatment option currently available. Starting from results showing that low-dose anthracyclines protect against sepsis in mice, we sought to find new causative treatment options to improve sepsis outcomes.MethodsSepsis was induced in mice, and different treatment options were evaluated regarding cytokine and biomarker expression, lung epithelial cell permeability, autophagy induction, and survival benefit. Results were validated in cell culture experiments and correlated with patient samples.FindingsEffective low-dose epirubicin treatment resulted in substantial downregulation of the sphingosine 1-phosphate (S1P) degrading enzyme S1P lyase (SPL). Consequent accumulation and secretion of S1P in lung parenchyma cells stimulated the S1P-receptor type 3 (S1PR3) and mitogen-activated protein kinases p38 and ERK, reducing tissue damage via increased disease tolerance. The protective effects of SPL inhibition were absent in S1PR3 deficient mice. Sepsis patients showed increased expression of SPL, stable expression of S1PR3, and increased levels of mucin-1 and surfactant protein D as indicators of lung damage.InterpretationOur work highlights a tissue-protective effect of SPL inhibition in sepsis due to activation of the S1P/S1PR3 axis and implies that SPL inhibitors and S1PR3 agonists might be potential therapeutics to protect against sepsis by increasing disease tolerance against infections.FundingThis study was supported by the Center for Sepsis Control and Care (CSCC), the German Research Foundation (DFG), RTG 1715 (to M. H. G. and I. R.) and the National Institutes of Health, Grant R01GM043880 (to S. S.).

| S-EPMC7381498 | biostudies-literature

Cancer cells utilize self-inflicted DNA breaks to evade growth limits imposed by exogenous genotoxic stress

Project description:Exposure to genotoxic challenge activates cell cycle checkpoints to prevent progression and propagation of deleterious DNA damage. We identify the activity of a nuclease, Caspase-activated DNase (CAD), in promoting G2 checkpoint control in cancer cells via the infliction of DNA breaks. To appreciate the genomic context of these breaks, we performed (genome wide ligation of 3’-hydroxy (OH) ends followed by sequencing), to map the endogenously inflicted DNA breaks following irradiation.

2022-03-28 | GSE171242 | GEO

Sphingosine 1-phosphate (S1P) reduces hepatocyte growth factor-induced migration of hepatocellular carcinoma cells via S1P receptor 2.

Project description:A bioactive lipid, sphingosine 1-phosphate (S1P), acts extracellularly as a potent mediator, and is implicated in the progression of various cancers including hepatocellular carcinoma (HCC). S1P exerts its functions by binding to five types of specific receptors, S1P receptor 1 (S1PR1), S1PR2, S1PR3, S1PR4 and S1PR5 on the plasma membrane. However, the exact roles of S1P and each S1PR in HCC cells remain to be clarified. In the present study, we investigated the effect of S1P on the hepatocyte growth factor (HGF)-induced migration of human HCC-derived HuH7 cells, and the involvement of each S1PR. S1P dose-dependently reduced the HGF-induced migration of HuH7 cells. We found that all S1PRs exist in the HuH7 cells. Among each selective agonist for five S1PRs, CYM5520, a selective S1PR2 agonist, significantly suppressed the HGF-induced HuH7 cell migration whereas selective agonists for S1PR1, S1PR3, S1PR4 or S1PR5 failed to affect the migration. The reduction of the HGF-induced migration by S1P was markedly reversed by treatment of JTE013, a selective antagonist for S1PR2, and S1PR2- siRNA. These results strongly suggest that S1P reduces the HGF-induced HCC cell migration via S1PR2. Our findings may provide a novel potential of S1PR2 to therapeutic strategy for metastasis of HCC.

| S-EPMC6292590 | biostudies-literature

Neonatal HDL Counteracts Placental Vascular Inflammation via S1P-S1PR1 Axis.

Project description:Placental inflammation and dysfunction during pregnancy are associated with short- and long-term adverse outcomes for the offspring. However, the mechanisms of vascular protection at the feto-placental interface are still poorly investigated. The high-density lipoprotein (HDL) associated sphingosine-1-phosphate (S1P) has been described as a powerful anti-inflammatory complex. This study aimed to elucidate the role of cord blood-derived HDL (nHDL) in feto-placental endothelial dysfunction. Here, we report that the exposure of primary fetal placental arterial endothelial cell (fPAEC) to healthy nHDL-S1P attenuated the ability of TNF? to activate NF-?B signaling and increase the expression of pro-inflammatory markers. Moreover, the angiotensin II (AngII)-induced reactive oxygen species (ROS) production was blunted in the presence of nHDL, whereas it was preserved when the cells were preincubated with S1P receptor antagonists, suggesting that S1P accounts for the vascular protective function of nHDL at the feto-placental unit. These results highlight the importance of HDL and S1P metabolism and signaling in pregnancy pathophysiology.

| S-EPMC7037016 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data