Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Two independently regulated Ca2+ entry mechanisms coexist in Jurkat T cells during T cell receptor antigen activation.

ABSTRACT: Receptor-mediated Ca2+ influx was studied in the human leukaemic T cell line, Jurkat. Stimulation of these cells through the T cell antigen-receptor complex with OKT3 (an antibody against the CD3 molecules of the T cell antigen-receptor complex), or inhibition of the endoplasmic reticular Ca(2+)-ATPase with thapsigargin, resulted in Ca2+ mobilization from intracellular stores and the activation of Ca2+ and Mn2+ entry. The rates of thapsigargin-induced Ca2+ and Mn2+ entry in Jurkat cells were 76% and 64% respectively of those observed after treatment of these cells with OKT3. The combined addition of thapsigargin plus OKT3 to Jurkat cells produced an enhanced effect on the sustained increase in the cytosolic free Ca2+ concentration that was greater than that obtained by addition of thapsigargin or OKT3 alone. The rates of Ca2+ and Mn2+ entry were increased to 119% and 112% respectively of the OKT3-induced rates. Taken together, these results suggest that the inositol 1,4,5-trisphosphate-sensitive Ca(2+)-pool-dependent bivalent cation entry only accounts for 57% and 52% respectively of the total OKT3-dependent Ca2+ and Mn2+ entry, and that the rest is mediated by second messenger(s). Thus two separate pathways coexist in regulating Ca2+ entry in Jurkat cells during activation mediated through the T cell receptor.

SUBMITTER: Chow SC

PROVIDER: S-EPMC1134373 | biostudies-other | 1993 Jul

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Similar Datasets

STIM1 controls endothelial barrier function independently of Orai1 and Ca2+ entry.

Project description:Endothelial barrier function is critical for tissue fluid homeostasis, and its disruption contributes to various pathologies, including inflammation and sepsis. Thrombin is an endogenous agonist that impairs endothelial barrier function. We showed that the thrombin-induced decrease in transendothelial electric resistance of cultured human endothelial cells required the endoplasmic reticulum-localized, calcium-sensing protein stromal interacting molecule 1 (STIM1), but was independent of Ca2+ entry across the plasma membrane and the Ca2+ release-activated Ca2+ channel protein Orai1, which is the target of STIM1 in the store-operated calcium entry pathway. We found that STIM1 coupled the thrombin receptor to activation of the guanosine triphosphatase RhoA, stimulation of myosin light chain phosphorylation, formation of actin stress fibers, and loss of cell-cell adhesion. Thus, STIM1 functions in pathways that are dependent on and independent of Ca2+ entry.

| S-EPMC4030669 | biostudies-literature

Ca2+ release and Ca2+ entry induced by rapid cytosolic alkalinization in Jurkat T-lymphocytes.

Project description:4-Aminopyridine (4-AP), a compound usually known as a K(+)-channel inhibitor, induced rapid cytosolic alkalinization from pH 7.15 to pH 7.4, and subsequently Ca2+ mobilization in the T-lymphocyte cell line Jurkat. Other weak bases, such as NH4Cl or triethanolamine, induced a smaller and/or slower increase in cytosolic pH, resulting in a lower or no detectable Ca2+ signal. In the presence of extracellular Ca2+, 4-AP mediated a rapid and sustained increase in the free cytosolic Ca2+ concentration similar to that obtained by T-cell receptor-mediated stimulation. In the absence of extracellular Ca2+, 4-AP transiently released Ca2+ from an intracellular store that is most likely identical with the agonist- and Ins(1,4,5)P3-sensitive Ca2+ pool of Jurkat T-cells. As possible mechanisms for Ca2+ release from this particular pool as induced by 4-AP we examined (i) formation of Ins(1,4,5)P3 and (ii) sensitization of the Ins(1,4,5)P3-receptor/Ca(2+)release system by increasing intracellular pH. Although 4-AP did not induce formation of inositol polyphosphates, as demonstrated by h.p.l.c. analysis, in permeabilized cells the dose-response curve for Ins(1,4,5)P3 was shifted to the left by changing the intracellular pH from 7.2 to 7.4. This indicated that sensitization of the Ins(1,4,5)P3-receptor/Ca(2+)-release system was responsible for the effects of 4-AP seen in intact cells. In conclusion, 4-AP appears a novel tool for depletion of the agonist-sensitive Ca2+ pool of T-cells without simultaneous formation of Ins(1,4,5)P3, thereby inducing capacitative Ca2+ entry in these cells.

| S-EPMC1137146 | biostudies-other

Mechanisms of STIM1 activation of store-independent leukotriene C4-regulated Ca2+ channels.

Project description:We recently showed, in primary vascular smooth muscle cells (VSMCs), that the platelet-derived growth factor activates canonical store-operated Ca(2+) entry and Ca(2+) release-activated Ca(2+) currents encoded by Orai1 and STIM1 genes. However, thrombin activates store-independent Ca(2+) selective channels contributed by both Orai3 and Orai1. These store-independent Orai3/Orai1 channels are gated by cytosolic leukotriene C4 (LTC4) and require STIM1 downstream LTC4 action. However, the source of LTC4 and the signaling mechanisms of STIM1 in the activation of this LTC4-regulated Ca(2+) (LRC) channel are unknown. Here, we show that upon thrombin stimulation, LTC4 is produced through the sequential activities of phospholipase C, diacylglycerol lipase, 5-lipo-oxygenease, and leukotriene C4 synthase. We show that the endoplasmic reticulum-resident STIM1 is necessary and sufficient for LRC channel activation by thrombin. STIM1 does not form sustained puncta and does not colocalize with Orai1 either under basal conditions or in response to thrombin. However, STIM1 is precoupled to Orai3 and Orai3/Orai1 channels under basal conditions as shown using Forster resonance energy transfer (FRET) imaging. The second coiled-coil domain of STIM1 is required for coupling to either Orai3 or Orai3/Orai1 channels and for LRC channel activation. We conclude that STIM1 employs distinct mechanisms in the activation of store-dependent and store-independent Ca(2+) entry pathways.

| S-EPMC3753864 | biostudies-other

K+ efflux agonists induce NLRP3 inflammasome activation independently of Ca2+ signaling.

Project description:Perturbation of intracellular ion homeostasis is a major cellular stress signal for activation of NLRP3 inflammasome signaling that results in caspase-1-mediated production of IL-1? and pyroptosis. However, the relative contributions of decreased cytosolic K(+) concentration versus increased cytosolic Ca(2+) concentration ([Ca(2+)]) remain disputed and incompletely defined. We investigated roles for elevated cytosolic [Ca(2+)] in NLRP3 activation and downstream inflammasome signaling responses in primary murine dendritic cells and macrophages in response to two canonical NLRP3 agonists (ATP and nigericin) that facilitate primary K(+) efflux by mechanistically distinct pathways or the lysosome-destabilizing agonist Leu-Leu-O-methyl ester. The study provides three major findings relevant to this unresolved area of NLRP3 regulation. First, increased cytosolic [Ca(2+)] was neither a necessary nor sufficient signal for the NLRP3 inflammasome cascade during activation by endogenous ATP-gated P2X7 receptor channels, the exogenous bacterial ionophore nigericin, or the lysosomotropic agent Leu-Leu-O-methyl ester. Second, agonists for three Ca(2+)-mobilizing G protein-coupled receptors (formyl peptide receptor, P2Y2 purinergic receptor, and calcium-sensing receptor) expressed in murine dendritic cells were ineffective as activators of rapidly induced NLRP3 signaling when directly compared with the K(+) efflux agonists. Third, the intracellular Ca(2+) buffer, BAPTA, and the channel blocker, 2-aminoethoxydiphenyl borate, widely used reagents for disruption of Ca(2+)-dependent signaling pathways, strongly suppressed nigericin-induced NLRP3 inflammasome signaling via mechanisms dissociated from their canonical or expected effects on Ca(2+) homeostasis. The results indicate that the ability of K(+) efflux agonists to activate NLRP3 inflammasome signaling can be dissociated from changes in cytosolic [Ca(2+)] as a necessary or sufficient signal.

| S-EPMC4390495 | biostudies-literature

Molecular Determinants for STIM1 Activation During Store- Operated Ca2+ Entry.

Project description:STIM/ORAI-mediated store-operated Ca2+ entry (SOCE) mediates a myriad of Ca2+-dependent cellular activities in mammals. Genetic defects in STIM1/ORAI1 lead to devastating severe combined immunodeficiency; whereas gain-offunction mutations in STIM1/ORAI1 are intimately associated with tubular aggregate myopathy. At molecular level, a decrease in the Ca2+ concentrations within the lumen of endoplasmic reticulum (ER) initiates multimerization of the STIM1 luminal domain to switch on the STIM1 cytoplasmic domain to engage and gate ORAI channels, thereby leading to the ultimate Ca2+ influx from the extracellular space into the cytosol. Despite tremendous progress made in dissecting functional STIM1-ORAI1 coupling, the activation mechanism of SOCE remains to be fully characterized.Building upon a robust fluorescence resonance energy transfer assay designed to monitor STIM1 intramolecular autoinhibition, we aimed to systematically dissect the molecular determinants required for the activation and oligomerization of STIM1.Here we showed that truncation of the STIM1 luminal domain predisposes STIM1 to adopt a more active conformation. Replacement of the single transmembrane (TM) domain of STIM1 by a more rigid dimerized TM domain of glycophorin A abolished STIM1 activation. But this adverse effect could be partially reversed by disrupting the TM dimerization interface. Moreover, our study revealed regions that are important for the optimal assembly of hetero-oligomers composed of full-length STIM1 with its minimal STIM1-ORAI activating region, SOAR.Our study clarifies the roles of major STIM1 functional domains in maintaining a quiescent configuration of STIM1 to prevent preactivation of SOCE.

| S-EPMC5563273 | biostudies-literature

Ba2+ stimulation of luteinizing-hormone release demonstrates two mechanisms of Ca2+ entry in gonadotrope cells.

Project description:Kinetic studies on gonadotropin-releasing-hormone (gonadoliberin, GnRH)-stimulated luteinizing-hormone (lutropin, LH) release in the cultured rat gonadotrope demonstrated a biphasic pattern of LH release. The first rapid phase of release was unaffected by the voltage-gated Ca2+-channel blockers methoxyverapamil (D600) and nifedipine [a dihydropyridine (DHP)], whereas the later second phase was partially inhibited by both drugs. These results suggested that the initial phase of LH release is independent of Ca2+ entry through dihydropyridine (DHP)-sensitive Ca2+ channels and might depend on entry of extracellular Ca2+ by another mechanism. These mechanisms were further studied by utilizing Ba2+ as a Ca2+ substitute. Ba2+, which freely permeates DHP-sensitive Ca2+ channels in the absence of GnRH, induced LH release which was sensitive to blockade by D600 and nifedipine. However, in the presence of the channel blockers, Ba2+-induced LH release could be elicited when GnRH was added to the system. This indicates that GnRH stimulates LH release by initially activating a DHP-insensitive Ca2+-entry mechanism and then a DHP-sensitive mechanism. The DHP-sensitive mechanism freely allows Ba2+ entry in the absence of GnRH-receptor occupancy, whereas the DHP-insensitive mechanism requires GnRH-receptor activation for Ba2+ entry.

| S-EPMC1138493 | biostudies-other

The Ca2+ export pump PMCA clears near-membrane Ca2+ to facilitate store-operated Ca2+ entry and NFAT activation.

Project description:Ca2+ signals, which facilitate pluripotent changes in cell fate, reflect the balance between cation entry and export. We found that overexpression of either isoform of the Ca2+-extruding plasma membrane calcium ATPase 4 (PMCA4) pump in Jurkat T cells unexpectedly increased activation of the Ca2+-dependent transcription factor nuclear factor of activated T cells (NFAT). Coexpression of the endoplasmic reticulum-resident Ca2+ sensor stromal interaction molecule 1 (STIM1) with the PMCA4b splice variant further enhanced NFAT activity; however, coexpression with PMCA4a depressed NFAT. No PMCA4 splice variant dependence in STIM1 association was observed, whereas partner of STIM1 (POST) preferentially associated with PMCA4b over PMCA4a, which enhanced, rather than inhibited, PMCA4 function. A comparison of global and near-membrane cytosolic Ca2+ abundances during store-operated Ca2+ entry revealed that PMCA4 markedly depressed near-membrane Ca2+ concentrations, particularly when PMCA4b was coexpressed with STIM1. PMCA4b closely associated with both POST and the store-operated Ca2+ channel Orai1. Furthermore, POST knockdown increased the near-membrane Ca2+ concentration, inhibiting the global cytosolic Ca2+ increase. These observations reveal an unexpected role for POST in coupling PMCA4 to Orai1 to promote Ca2+ entry during T cell activation through Ca2+ disinhibition.

| S-EPMC6800072 | biostudies-literature

Lysophosphatidic acid-sensitive intracellular Ca2+ store does not regulate Ca2+ entry at plasma membrane in Jurkat human T-cells.

Project description:In Jurkat T cells, the anti-CD3 antibody OKT3 and thapsigargin (TG) elevated the cytoplasmic free Ca2+ concentration ([Ca2+]i), after which it decreased to a sustained, elevated level. In contrast, lysophosphatidic acid (LPA) increased [Ca2+]i only briefly and transiently, after which it declined to the resting level of [Ca2+]i even in the presence of extracellular Ca2+. OKT3 increased Ins(1,4,5)P3 formation but neither LPA nor TG did. In the absence of extracellular Ca2+, the addition of OKT3 did not affect an elevation of [Ca2+]i induced by the subsequent addition of LPA and vice versa. In permeabilized Jurkat cells, the addition of Ins(1,4,5)P3 released Ca2+; this was inhibited by heparin, whereas LPA released Ca2+ even in the presence of heparin. cADP-ribose released Ca2+; this was additive with LPA-induced Ca2+ release and vice versa in permeabilized Jurkat cells. LPA did not stimulate Ca2+ entry and 45Ca2+ uptake but OKT3 and TG did. LPA, OKT3 and TG did not affect the sustained elevation of [Ca2+]i induced by ionomycin. The present results suggest that at least three kinds of intracellular Ca2+ stores, which are Ins(1,4,5)P3,-cADP-ribose- and LPA-sensitive, exist in Jurkat T cells, and that the LPA-sensitive intracellular Ca2+ store does not regulate Ca2+ entry at the plasma membrane.

| S-EPMC1217781 | biostudies-other

Antigen-Specific T-Cell Activation Independently of the MHC: Chimeric Antigen Receptor-Redirected T Cells.

Project description:Adoptive T-cell therapy has recently shown promise in initiating a lasting anti-tumor response with spectacular therapeutic success in some cases. Specific T-cell therapy, however, is limited since a number of cancer cells are not recognized by T cells due to various mechanisms including the limited availability of tumor-specific T cells and deficiencies in antigen processing or major histocompatibility complex (MHC) expression of cancer cells. To make adoptive cell therapy applicable for the broad variety of cancer entities, patient's T cells are engineered ex vivo with pre-defined specificity by a recombinant chimeric antigen receptor (CAR) which consists in the extracellular part of an antibody-derived domain for binding with a "tumor-associated antigen" and in the intracellular part of a T-cell receptor (TCR)-derived signaling moiety for T-cell activation. The specificity of CAR-mediated T-cell recognition is defined by the antibody domain, is independent of MHC presentation and can be extended to any target for which an antibody is available. We discuss the advantages and limitations of MHC-independent T-cell targeting by an engineered CAR in comparison to TCR modified T cells and the impact of the CAR activation threshold on redirected T-cell activation. Finally we review most significant progress recently made in early stage clinical trials to treat cancer.

| S-EPMC3822734 | biostudies-literature

Ca2+ entry following P2X receptor activation induces IP3 receptor-mediated Ca2+ release in myocytes from small renal arteries.

Project description:P2X receptors mediate sympathetic control and autoregulation of the renal circulation triggering contraction of renal vascular smooth muscle cells (RVSMCs) via an elevation of intracellular Ca(2+) concentration ([Ca(2+) ](i) ). Although it is well-appreciated that the myocyte Ca(2+) signalling system is composed of microdomains, little is known about the structure of the [Ca(2+) ](i) responses induced by P2X receptor stimulation in vascular myocytes.Using confocal microscopy, perforated-patch electrical recordings, immuno-/organelle-specific staining, flash photolysis and RT-PCR analysis we explored, at the subcellular level, the Ca(2+) signalling system engaged in RVSMCs on stimulation of P2X receptors with the selective agonist ??-methylene ATP (??-meATP).RT-PCR analysis of single RVSMCs showed the presence of genes encoding inositol 1,4,5-trisphosphate receptor type 1(IP(3) R1) and ryanodine receptor type 2 (RyR2). The amplitude of the [Ca(2+) ](i) transients depended on ??-meATP concentration. Depolarization induced by 10?µmol·L(-1) ??-meATP triggered an abrupt Ca(2+) release from sub-plasmalemmal ('junctional') sarcoplasmic reticulum enriched with IP(3) Rs but poor in RyRs. Depletion of calcium stores, block of voltage-gated Ca(2+) channels (VGCCs) or IP(3) Rs suppressed the sub-plasmalemmal [Ca(2+) ](i) upstroke significantly more than block of RyRs. The effect of calcium store depletion or IP(3) R inhibition on the sub-plasmalemmal [Ca(2+) ](i) upstroke was attenuated following block of VGCCs.Depolarization of RVSMCs following P2X receptor activation induces IP(3) R-mediated Ca(2+) release from sub-plasmalemmal ('junctional') sarcoplasmic reticulum, which is activated mainly by Ca(2+) influx through VGCCs. This mechanism provides convergence of signalling pathways engaged in electromechanical and pharmacomechanical coupling in renal vascular myocytes.

| S-EPMC3057298 | 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