Adenosine Triphosphate–Induced Shedding of CD23 and L-Selectin (CD62L) From Lymphocytes Is Mediated by the Same Receptor but Different Metalloproteases

Blood ◽  
1998 ◽  
Vol 92 (3) ◽  
pp. 946-951 ◽  
Author(s):  
B. Gu ◽  
L.J. Bendall ◽  
J.S. Wiley
Keyword(s):  
Adenosine Triphosphate ◽  
Phorbol Ester ◽  
P2x7 Receptor ◽  
Transmembrane Protein ◽  
Lymphocytic Leukemia ◽  
P2x7 Receptors ◽  
Extracellular Adenosine ◽  
Zinc Chelator ◽  
High Concentrations ◽  
American Society

CD23 is a transmembrane protein expressed on the surface of B-lymphocytes that binds IgE, CD21, CD11b, and CD11c. High concentrations of soluble CD23 and L-selectin are found in the serum of patients with B-chronic lymphocytic leukemia (B-CLL). Because extracellular adenosine triphosphate (ATP) causes shedding of L-selectin via activation of P2Z/P2X7 receptors expressed on B-CLL lymphocytes, we studied the effect of ATP on shedding of CD23. ATP-induced shedding of CD23 at an initial rate of 12% of that for L-selectin, whereas the EC50 for ATP was identical (35 μmol/L) for shedding of both molecules. Furthermore, benzoylbenzoyl ATP also produced shedding of CD23 and L-selectin with the same agonist EC50 values for both (10 μmol/L). Inactivation of the P2Z/P2X7 receptor by preincubation with oxidized ATP abolished ATP-induced shedding of both molecules. Moreover, KN-62, the most potent inhibitor for the P2Z/P2X7 receptor, inhibited ATP-induced shedding of both CD23 and L-selectin with the same IC50 (12 nmol/L). Ro 31-9790, a membrane permeant zinc chelator that inhibits the phorbol-ester-stimulated shedding of L-selectin, also inhibited shedding of CD23 from B-CLL lymphocytes. However, the IC50 for this inhibition by Ro31-9790 was different for L-selectin and CD23 (83 v 6 μmol/L, respectively). Although L-selectin was completely shed by incubation of cells with phorbol-ester, CD23 was not lost under these conditions. The data show that extracellular ATP induces shedding of L-selectin and CD23 from B-CLL lymphocytes by an action mediated by the P2Z/P2X7 receptor. However, different membrane metalloproteases seem to mediate the shedding of L-selectin and CD23. © 1998 by The American Society of Hematology.

Adenosine Triphosphate–Induced Shedding of CD23 and L-Selectin (CD62L) From Lymphocytes Is Mediated by the Same Receptor but Different Metalloproteases

Blood ◽  
1998 ◽  
Vol 92 (3) ◽  
pp. 946-951 ◽  
Author(s):  
B. Gu ◽  
L.J. Bendall ◽  
J.S. Wiley
Keyword(s):  
Adenosine Triphosphate ◽  
Phorbol Ester ◽  
P2x7 Receptor ◽  
Transmembrane Protein ◽  
Lymphocytic Leukemia ◽  
P2x7 Receptors ◽  
Extracellular Adenosine ◽  
Zinc Chelator ◽  
High Concentrations ◽  
American Society

Abstract CD23 is a transmembrane protein expressed on the surface of B-lymphocytes that binds IgE, CD21, CD11b, and CD11c. High concentrations of soluble CD23 and L-selectin are found in the serum of patients with B-chronic lymphocytic leukemia (B-CLL). Because extracellular adenosine triphosphate (ATP) causes shedding of L-selectin via activation of P2Z/P2X7 receptors expressed on B-CLL lymphocytes, we studied the effect of ATP on shedding of CD23. ATP-induced shedding of CD23 at an initial rate of 12% of that for L-selectin, whereas the EC50 for ATP was identical (35 μmol/L) for shedding of both molecules. Furthermore, benzoylbenzoyl ATP also produced shedding of CD23 and L-selectin with the same agonist EC50 values for both (10 μmol/L). Inactivation of the P2Z/P2X7 receptor by preincubation with oxidized ATP abolished ATP-induced shedding of both molecules. Moreover, KN-62, the most potent inhibitor for the P2Z/P2X7 receptor, inhibited ATP-induced shedding of both CD23 and L-selectin with the same IC50 (12 nmol/L). Ro 31-9790, a membrane permeant zinc chelator that inhibits the phorbol-ester-stimulated shedding of L-selectin, also inhibited shedding of CD23 from B-CLL lymphocytes. However, the IC50 for this inhibition by Ro31-9790 was different for L-selectin and CD23 (83 v 6 μmol/L, respectively). Although L-selectin was completely shed by incubation of cells with phorbol-ester, CD23 was not lost under these conditions. The data show that extracellular ATP induces shedding of L-selectin and CD23 from B-CLL lymphocytes by an action mediated by the P2Z/P2X7 receptor. However, different membrane metalloproteases seem to mediate the shedding of L-selectin and CD23. © 1998 by The American Society of Hematology.

scholarly journals Extracellular adenosine triphosphate increases cation permeability of chronic lymphocytic leukemic lymphocytes

Blood ◽  
1989 ◽  
Vol 73 (5) ◽  
pp. 1316-1323 ◽  
Author(s):  
JS Wiley ◽  
GR Dubyak
Keyword(s):  
Adenosine Triphosphate ◽  
Fold Increase ◽  
Normal Subjects ◽  
Peripheral Blood Lymphocytes ◽  
Extracellular Atp ◽  
Total Cell ◽  
Lymphocytic Leukemia ◽  
Maximal Response ◽  
Extracellular Adenosine ◽  
Cation Permeability

Abstract Extracellular adenosine triphosphate (ATP) is known to reversibly increase the cation permeability of a variety of freshly isolated and cultured cell types. In this study the effects of extracellular ATP were studied using peripheral blood lymphocytes (PBL) isolated from both normal subjects and from patients with chronic lymphocytic leukemia (CLL). Changes in the permeability to Na+, Rb+, and Li+ ions were measured using conventional isotope and flame photometry techniques. In addition, changes in cytosolic (Ca2+) were fluorimetrically monitored to assess possible changes in net Ca2+ influx. ATP produced a 12-fold increase in 22Na+ influx into CLL cells but only a 3.5-fold increase in this flux in PBL cells. A maximal response was produced by 0.1 mmol/L ATP in the absence of Mg2+, while a twofold molar excess of Mg2+ over ATP abolished the response. ATP had no effect on the passive (ouabain-insensitive) 86Rb+ influx into PBL cells but stimulated this flux by fivefold in the CLL cells. Li+ influx into CLL cells was also stimulated threefold by ATP. Under these same conditions ATP also produced a net increase in total cell Na and a decrease in total cell K in the CLL cells. Exclusion of two normally impermeable dyes, trypan blue and ethidium bromide, was not altered in the ATP-treated CLL cells. Finally, extracellular ATP (3 mmol/L) produced no significant change in the cytosolic (Ca2+) of normal, monocyte-depleted populations of PBL. Conversely, this same concentration of ATP produced a very rapid (complete within 30 seconds) and a significant (an average threefold peak change) increase in the cytosolic (Ca2+) of cell preparations derived from five out of nine CLL patients. In these latter CLL cells, the ATP-induced elevation in cytosolic (Ca2+) appeared to be due to a net increase in Ca2+ influx, since no elevations were observed when the extracellular (Ca2+) was reduced to less than 0.1 mmol/L. These actions of ATP were specific in that equimolar concentrations of other nucleotides were without effect. These data indicate that treatment of CLL lymphocytes with extracellular ATP4 produces large increases in cation permeability. In contrast, there is less or no ATP-induced permeabilization of normal PBL.

scholarly journals P2X7 receptors activate protein kinase D and p42/p44 mitogen-activated protein kinase (MAPK) downstream of protein kinase C

2002 ◽  
Vol 366 (3) ◽  
pp. 745-755 ◽  
Author(s):  
Michelle D. BRADFORD ◽  
Stephen P. SOLTOFF
Keyword(s):  
Protein Kinase ◽  
Tyrosine Kinases ◽  
P2x7 Receptor ◽  
Kinase Inhibitor ◽  
Mitogen Activated Protein Kinase ◽  
Protein Kinase D ◽  
Dependent Manner ◽  
P2x7 Receptors ◽  
High Concentrations

Protein kinase D (PKD), also called protein kinase Cμ (PKCμ), is a serine/threonine kinase that has unique enzymic and structural properties distinct from members of the PKC family of proteins. In freshly isolated rat parotid acinar salivary cells, extracellular ATP rapidly increased the activity and phosphorylation of PKD. The stimulation by ATP required high concentrations, was mimicked by the P2X7 receptor ligand BzATP [2′- and 3′-O-(4-benzoylbenzoyl)ATP], and was blocked by Mg2+ and 4,4′-di-isothiocyano-2,2′-stilbene disulphonate (DIDS), suggesting that activation of PKD was mediated by P2X7 receptors, which are ligand-gated non-selective cation channels. Phorbol ester (PMA) and the activation of muscarinic and substance P receptors also increased PKD activity. PKC inhibitors blocked ligand-dependent PKD activation and phosphorylation, determined by in vitro phosphorylation studies and by phospho-specific antibodies to two activation loop sites (Ser744 and Ser748) and an autophosphorylation site (Ser916). ATP and BzATP also increased the tyrosine phosphorylation and activity of PKCΔ, and these stimuli also increased extracellular signal-regulated protein kinase (ERK) 1/2 activity in a PKC-dependent manner. PKD activation was not promoted by pervanadate (an inhibitor of tyrosine phosphatases) and was not blocked by PP1 (an inhibitor of Src family kinases) or genistein (a tyrosine kinase inhibitor), suggesting that tyrosine kinases and phosphatases did not play a major role in PKD activation. P2X7 receptor-mediated signalling events were not dependent on Ca2+ entry. These studies indicate that PKC is involved in cellular signalling initiated by P2X7 receptors as well as by G-protein-coupled receptors, and demonstrate that PKD and ERK1/2 are activated in similar PKC-dependent signalling pathways initiated by these diverse receptor types.

scholarly journals Extracellular adenosine triphosphate increases cation permeability of chronic lymphocytic leukemic lymphocytes

Blood ◽  
1989 ◽  
Vol 73 (5) ◽  
pp. 1316-1323
Author(s):  
JS Wiley ◽  
GR Dubyak
Keyword(s):  
Adenosine Triphosphate ◽  
Fold Increase ◽  
Normal Subjects ◽  
Peripheral Blood Lymphocytes ◽  
Extracellular Atp ◽  
Total Cell ◽  
Lymphocytic Leukemia ◽  
Maximal Response ◽  
Extracellular Adenosine ◽  
Cation Permeability

Extracellular adenosine triphosphate (ATP) is known to reversibly increase the cation permeability of a variety of freshly isolated and cultured cell types. In this study the effects of extracellular ATP were studied using peripheral blood lymphocytes (PBL) isolated from both normal subjects and from patients with chronic lymphocytic leukemia (CLL). Changes in the permeability to Na+, Rb+, and Li+ ions were measured using conventional isotope and flame photometry techniques. In addition, changes in cytosolic (Ca2+) were fluorimetrically monitored to assess possible changes in net Ca2+ influx. ATP produced a 12-fold increase in 22Na+ influx into CLL cells but only a 3.5-fold increase in this flux in PBL cells. A maximal response was produced by 0.1 mmol/L ATP in the absence of Mg2+, while a twofold molar excess of Mg2+ over ATP abolished the response. ATP had no effect on the passive (ouabain-insensitive) 86Rb+ influx into PBL cells but stimulated this flux by fivefold in the CLL cells. Li+ influx into CLL cells was also stimulated threefold by ATP. Under these same conditions ATP also produced a net increase in total cell Na and a decrease in total cell K in the CLL cells. Exclusion of two normally impermeable dyes, trypan blue and ethidium bromide, was not altered in the ATP-treated CLL cells. Finally, extracellular ATP (3 mmol/L) produced no significant change in the cytosolic (Ca2+) of normal, monocyte-depleted populations of PBL. Conversely, this same concentration of ATP produced a very rapid (complete within 30 seconds) and a significant (an average threefold peak change) increase in the cytosolic (Ca2+) of cell preparations derived from five out of nine CLL patients. In these latter CLL cells, the ATP-induced elevation in cytosolic (Ca2+) appeared to be due to a net increase in Ca2+ influx, since no elevations were observed when the extracellular (Ca2+) was reduced to less than 0.1 mmol/L. These actions of ATP were specific in that equimolar concentrations of other nucleotides were without effect. These data indicate that treatment of CLL lymphocytes with extracellular ATP4 produces large increases in cation permeability. In contrast, there is less or no ATP-induced permeabilization of normal PBL.

scholarly journals Functional Coupling between the P2X7 Receptor and Pannexin-1 Channel in Rat Trigeminal Ganglion Neurons

2021 ◽  
Vol 22 (11) ◽  
pp. 5978
Author(s):  
Hiroyuki Inoue ◽  
Hidetaka Kuroda ◽  
Wataru Ofusa ◽  
Sadao Oyama ◽  
Maki Kimura ◽  
...  
Keyword(s):  
Trigeminal Ganglion ◽  
P2x7 Receptor ◽  
P2x Receptor ◽  
Functional Coupling ◽  
Dependent Manner ◽  
High Concentration ◽  
Receptor Antagonists ◽  
P2x7 Receptors ◽  
Pannexin 1 ◽  
Ganglion Neurons

The ionotropic P2X receptor, P2X7, is believed to regulate and/or generate nociceptive pain, and pain in several neuropathological diseases. Although there is a known relationship between P2X7 receptor activity and pain sensing, its detailed functional properties in trigeminal ganglion (TG) neurons remains unclear. We examined the electrophysiological and pharmacological characteristics of the P2X7 receptor and its functional coupling with other P2X receptors and pannexin-1 (PANX1) channels in primary cultured rat TG neurons, using whole-cell patch-clamp recordings. Application of ATP and Bz-ATP induced long-lasting biphasic inward currents that were more sensitive to extracellular Bz-ATP than ATP, indicating that the current was carried by P2X7 receptors. While the biphasic current densities of the first and second components were increased by Bz-ATP in a concentration dependent manner; current duration was only affected in the second component. These currents were significantly inhibited by P2X7 receptor antagonists, while only the second component was inhibited by P2X1, 3, and 4 receptor antagonists, PANX1 channel inhibitors, and extracellular ATPase. Taken together, our data suggests that autocrine or paracrine signaling via the P2X7-PANX1-P2X receptor/channel complex may play important roles in several pain sensing pathways via long-lasting neuronal activity driven by extracellular high-concentration ATP following tissue damage in the orofacial area.

scholarly journals A widespread toxin−antitoxin system exploiting growth control via alarmone signaling

2020 ◽  
Vol 117 (19) ◽  
pp. 10500-10510 ◽  
Author(s):  
Steffi Jimmy ◽  
Chayan Kumar Saha ◽  
Tatsuaki Kurata ◽  
Constantine Stavropoulos ◽  
Sofia Raquel Alves Oliveira ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Adenosine Triphosphate ◽  
Bacterial Growth ◽  
Growth Control ◽  
Genomic Context ◽  
Guanosine Triphosphate ◽  
Functional Roles ◽  
Bacterial Transcription ◽  
Signaling Mechanisms ◽  
High Concentrations

Under stressful conditions, bacterial RelA-SpoT Homolog (RSH) enzymes synthesize the alarmone (p)ppGpp, a nucleotide second messenger. (p)ppGpp rewires bacterial transcription and metabolism to cope with stress, and, at high concentrations, inhibits the process of protein synthesis and bacterial growth to save and redirect resources until conditions improve. Single-domain small alarmone synthetases (SASs) are RSH family members that contain the (p)ppGpp synthesis (SYNTH) domain, but lack the hydrolysis (HD) domain and regulatory C-terminal domains of the long RSHs such as Rel, RelA, and SpoT. We asked whether analysis of the genomic context of SASs can indicate possible functional roles. Indeed, multiple SAS subfamilies are encoded in widespread conserved bicistronic operon architectures that are reminiscent of those typically seen in toxin−antitoxin (TA) operons. We have validated five of these SASs as being toxic (toxSASs), with neutralization by the protein products of six neighboring antitoxin genes. The toxicity of Cellulomonas marina toxSAS FaRel is mediated by the accumulation of alarmones ppGpp and ppApp, and an associated depletion of cellular guanosine triphosphate and adenosine triphosphate pools, and is counteracted by its HD domain-containing antitoxin. Thus, the ToxSAS–antiToxSAS system with its multiple different antitoxins exemplifies how ancient nucleotide-based signaling mechanisms can be repurposed as TA modules during evolution, potentially multiple times independently.

Triggering of CD40 Antigen Inhibits Fludarabine-Induced Apoptosis in B Chronic Lymphocytic Leukemia Cells

Blood ◽  
1998 ◽  
Vol 92 (3) ◽  
pp. 990-995 ◽  
Author(s):  
Maria Fiammetta Romano ◽  
Annalisa Lamberti ◽  
Pierfrancesco Tassone ◽  
Fiorella Alfinito ◽  
Silvia Costantini ◽  
...  
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Consensus Sequence ◽  
Significant Proportion ◽  
Lymphocytic Leukemia ◽  
Antiapoptotic Effect ◽  
Apoptotic Effect ◽  
American Society ◽  
Induced Apoptosis ◽  
Decoy Oligonucleotide

Abstract We analyzed the effect of CD40 triggering on the fludarabine-induced apoptosis of B chronic lymphocytic leukemia (B-CLL) cells. Peripheral blood samples obtained from 15 patients were incubated with fludarabine in the absence or the presence of the anti-CD40 monoclonal antibody (MoAb) G28-5. In 12 patients a significant proportion of apoptotic cells, ranging from 22% to 38% (mean ± SE: 28.5 ± 1.6), were detected after 3 days of culture. In 9 of these samples, the addition of G28-5 reduced apoptosis by at least 30.1% and by 57.1% ± 7.8% on average (P = .0077). Because the CD40 antigen activates NF-κB/Rel transcription factors in B cells, and NF-κB/Rel complexes can inhibit cell apoptosis, we investigated whether the antiapoptotic effect of G28-5, in our system, could be related to modulation of NF-κB/Rel activity. As expected, B-CLL cells displayed significant levels of nuclear NF-κB/Rel activity; p50, RelA, and c-Rel components of the NF-κB/Rel protein family were identified in these complexes. After exposure to fludarabine, NF-κB/Rel complexes were decreased in the nuclei. The addition of G28-5 upregulated the NF-κB/Rel levels. To determine the involvement of NF-κB/Rel activity in the G28-5–mediated inhibition of apoptosis, we blocked the transcription factor with a decoy oligonucleotide, corresponding to the NF-κB/Rel consensus sequence. Cells incubated with the anti-CD40 MoAb in the presence of the decoy oligonucleotide but not a control oligonucleotide displayed a complete impairment of the G28-5 antiapoptotic effect, indicating that NF-κB/Rel activity was required for the inhibition of apoptosis. These results suggest that CD40 triggering in vivo could counteract the apoptotic effect of fludarabine on B-CLL cells and that its neutralization, or the use of NF-κB/Rel inhibitors, could improve the therapeutic effect of fludarabine. © 1998 by The American Society of Hematology.

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