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1.
Mol Psychiatry ; 24(1): 108-125, 2019 01.
Article in English | MEDLINE | ID: mdl-29934546

ABSTRACT

Extracellular aggregates of amyloid ß (Aß) peptides, which are characteristic of Alzheimer's disease (AD), act as an essential trigger for glial cell activation and the release of ATP, leading to the stimulation of purinergic receptors, especially the P2X7 receptor (P2X7R). However, the involvement of P2X7R in the development of AD is still ill-defined regarding the dual properties of this receptor. Particularly, P2X7R activates the NLRP3 inflammasome leading to the release of the pro-inflammatory cytokine, IL-1ß; however, P2X7R also induces cleavage of the amyloid precursor protein generating Aß peptides or the neuroprotective fragment sAPPα. We thus explored in detail the functions of P2X7R in AD transgenic mice. Here, we show that P2X7R deficiency reduced Aß lesions, rescued cognitive deficits and improved synaptic plasticity in AD mice. However, the lack of P2X7R did not significantly affect the release of IL-1ß or the levels of non-amyloidogenic fragment, sAPPα, in AD mice. Instead, our results show that P2X7R plays a critical role in Aß peptide-mediated release of chemokines, particularly CCL3, which is associated with pathogenic CD8+ T cell recruitment. In conclusion, our study highlights a novel detrimental function of P2X7R in chemokine release and supports the notion that P2X7R may be a promising therapeutic target for AD.


Subject(s)
Alzheimer Disease/genetics , Alzheimer Disease/metabolism , Receptors, Purinergic P2X7/genetics , Receptors, Purinergic P2X7/metabolism , Amyloid beta-Protein Precursor/genetics , Amyloid beta-Protein Precursor/metabolism , Animals , Cytokines/metabolism , Disease Models, Animal , Humans , Inflammasomes/metabolism , Interleukin-1beta/genetics , Interleukin-1beta/metabolism , Mice , Mice, Transgenic , NLR Family, Pyrin Domain-Containing 3 Protein/metabolism
2.
J Biol Chem ; 287(41): 34583-95, 2012 Oct 05.
Article in English | MEDLINE | ID: mdl-22891241

ABSTRACT

The amyloid precursor protein (APP) can be cleaved by α-secretases in neural cells to produce the soluble APP ectodomain (sAPPα), which is neuroprotective. We have shown previously that activation of the purinergic P2X7 receptor (P2X7R) triggers sAPPα shedding from neural cells. Here, we demonstrate that the activation of ezrin, radixin, and moesin (ERM) proteins is required for the P2X7R-dependent proteolytic processing of APP leading to sAPPα release. Indeed, the down-regulation of ERM by siRNA blocked the P2X7R-dependent shedding of sAPPα. We also show that P2X7R stimulation triggered the phosphorylation of ERM. Thus, ezrin translocates to the plasma membrane to interact with P2X7R. Using specific pharmacological inhibitors, we established the order in which several enzymes trigger the P2X7R-dependent release of sAPPα. Thus, a Rho kinase and the MAPK modules ERK1/2 and JNK act upstream of ERM, whereas a PI3K activity is triggered downstream. For the first time, this work identifies ERM as major partners in the regulated non-amyloidogenic processing of APP.


Subject(s)
Amyloid beta-Protein Precursor/metabolism , Cytoskeletal Proteins/metabolism , Membrane Proteins/metabolism , Microfilament Proteins/metabolism , Proteolysis , Receptors, Purinergic P2X7/metabolism , Amyloid beta-Protein Precursor/genetics , Animals , Cell Line, Tumor , Cytoskeletal Proteins/genetics , HEK293 Cells , Humans , Membrane Proteins/genetics , Mice , Microfilament Proteins/genetics , Mitogen-Activated Protein Kinase 1/genetics , Mitogen-Activated Protein Kinase 1/metabolism , Mitogen-Activated Protein Kinase 3/genetics , Mitogen-Activated Protein Kinase 3/metabolism , Phosphatidylinositol 3-Kinases/genetics , Phosphatidylinositol 3-Kinases/metabolism , Receptors, Purinergic P2X7/genetics , rho-Associated Kinases/genetics , rho-Associated Kinases/metabolism
3.
J Biol Chem ; 286(4): 2596-606, 2011 Jan 28.
Article in English | MEDLINE | ID: mdl-21081501

ABSTRACT

The amyloid precursor protein (APP) is cleaved by ß- and γ-secretases to generate the ß-amyloid (Aß) peptides, which are present in large amounts in the amyloid plaques of Alzheimer disease (AD) patient brains. Non-amyloidogenic processing of APP by α-secretases leads to proteolytic cleavage within the Aß peptide sequence and shedding of the soluble APP ectodomain (sAPPα), which has been reported to be endowed with neuroprotective properties. In this work, we have shown that activation of the purinergic receptor P2X7 (P2X7R) stimulates sAPPα release from mouse neuroblastoma cells expressing human APP, from human neuroblastoma cells and from mouse primary astrocytes or neural progenitor cells. sAPPα shedding is inhibited by P2X7R antagonists or knockdown of P2X7R with specific small interfering RNA (siRNA) and is not observed in neural cells from P2X7R-deficient mice. P2X7R-dependent APP-cleavage is independent of extracellular calcium and strongly inhibited by hydroxamate-based metalloprotease inhibitors, TAPI-2 and GM6001. However, knockdown of a disintegrin and metalloproteinase-9 (ADAM9), ADAM10 and ADAM17 by specific siRNA, known to have α-secretase activity, does not block the P2X7R-dependent non-amyloidogenic pathway. Using several specific pharmacological inhibitors, we demonstrate that the mitogen-activated protein kinase modules Erk1/2 and JNK are involved in P2X7R-dependent α-secretase activity. Our study suggests that P2X7R, which is expressed in hippocampal neurons and glial cells, is a potential therapeutic target in AD.


Subject(s)
Amyloid Precursor Protein Secretases/metabolism , Amyloid beta-Protein Precursor/metabolism , Astrocytes/metabolism , Neurons/metabolism , Receptors, Purinergic P2X7/metabolism , Stem Cells/metabolism , ADAM Proteins/antagonists & inhibitors , ADAM Proteins/genetics , ADAM Proteins/metabolism , Alzheimer Disease/drug therapy , Alzheimer Disease/genetics , Alzheimer Disease/metabolism , Amyloid Precursor Protein Secretases/antagonists & inhibitors , Amyloid Precursor Protein Secretases/genetics , Amyloid beta-Protein Precursor/genetics , Animals , Cell Line, Tumor , Dipeptides/pharmacology , Gene Knockdown Techniques , Hippocampus/metabolism , Humans , Hydroxamic Acids/pharmacology , MAP Kinase Kinase 4/antagonists & inhibitors , MAP Kinase Kinase 4/genetics , MAP Kinase Kinase 4/metabolism , Mice , Mice, Mutant Strains , Mitogen-Activated Protein Kinase 3/antagonists & inhibitors , Mitogen-Activated Protein Kinase 3/genetics , Mitogen-Activated Protein Kinase 3/metabolism , Protease Inhibitors/pharmacology , Protein Structure, Tertiary , Receptors, Purinergic P2X7/genetics
4.
Eur J Immunol ; 41(6): 1696-708, 2011 Jun.
Article in English | MEDLINE | ID: mdl-21469107

ABSTRACT

Activated B cells can regulate immunity and have been envisaged as a potential cell-based therapy for treating autoimmune diseases. However, activated human B cells can also propagate immune responses, and the effects resulting from their infusion into patients cannot be predicted. This led us to consider resting B cells, which in contrast are poorly immunogenic, as an alternative cellular platform for the suppression of unwanted immunity. Here, we report that resting B cells can be directly engineered with lentiviral vectors to express antigens in a remarkably simple, rapid, and effective way. Notably, this neither required nor induced activation of the B cells. With this approach we were able to produce reprogrammed resting B cells that inhibited antigen-specific CD4(+) T cells, CD8(+) T cells, and B cells upon adoptive transfer in mice. Furthermore, resting B cells engineered to ectopically express myelin oligodendrocyte glycoprotein antigen protected recipient mice from severe disability and demyelination in EAE, and even induced complete remission from disease in mice lacking functional natural Tregs, which otherwise developed chronic paralysis. In conclusion, our study introduces reprogrammed quiescent B cells as a novel tool for suppressing undesirable immunity.


Subject(s)
B-Lymphocytes/metabolism , Cell- and Tissue-Based Therapy , Encephalomyelitis, Autoimmune, Experimental/immunology , T-Lymphocyte Subsets/metabolism , T-Lymphocytes, Regulatory/metabolism , Adoptive Transfer , Animals , B-Lymphocytes/immunology , B-Lymphocytes/pathology , B-Lymphocytes/transplantation , Cell Differentiation/genetics , Cells, Cultured , Chronic Disease , Clonal Anergy , Disease Progression , Encephalomyelitis, Autoimmune, Experimental/physiopathology , Encephalomyelitis, Autoimmune, Experimental/therapy , Genetic Engineering , Humans , Immunosuppression Therapy , Interleukin-10/genetics , Mice , Mice, Knockout , Myelin Proteins , Myelin-Associated Glycoprotein/genetics , Myelin-Associated Glycoprotein/immunology , Myelin-Associated Glycoprotein/metabolism , Myelin-Oligodendrocyte Glycoprotein , T-Lymphocyte Subsets/immunology , T-Lymphocyte Subsets/pathology , T-Lymphocytes, Regulatory/immunology , T-Lymphocytes, Regulatory/pathology , Transgenes/genetics
5.
Biomed J ; 45(2): 286-288, 2022 04.
Article in English | MEDLINE | ID: mdl-35430421

ABSTRACT

This special edition summarizes major advances in our understanding of signaling by T lymphocytes. T cell interactions with antigen-presenting cells (APCs) and other immune cells are characterized by changes in T cell adhesion and major rearrangements of the actin cytoskeleton. This issue describes some of the mediators of these changes both within the T cells and on the T cell surface. The five articles focus on "inside-out integrin signaling" in T cells, components of the immunological synapse between lymphocyte and APCs, an unexpected role for T cell receptor (TCR) signaling from endosomes, transfer of membrane constituents from APCs to T cells via trogocytosis, immune deficiencies in these T cell signaling pathways, and the role of thymocyte-expressed molecule involved in selection (THEMIS) in thymocyte development and peripheral T cell function.


Subject(s)
Receptors, Antigen, T-Cell , T-Lymphocytes , Humans , Immunological Synapses/metabolism , Lymphocyte Activation , Receptors, Antigen, T-Cell/metabolism , Signal Transduction
6.
Front Immunol ; 13: 957008, 2022.
Article in English | MEDLINE | ID: mdl-36248812

ABSTRACT

The severe lymphoproliferative and lupus diseases developed by MRL/lpr mice depend on interactions between the Fas lpr mutation and MRL genetic background. Thus, the Fas lpr mutation causes limited disease in C57BL/6 mice. We previously found that accumulating B220+ CD4-CD8- double negative (DN) T cells in MRL/lpr mice show defective P2X7 receptor ( P2X7)-induced cellular functions, suggesting that P2X7 contributes to T-cell homeostasis, along with Fas. Therefore, we generated a B6/lpr mouse strain (called B6/lpr-p2x7KO) carrying homozygous P2X7 knockout alleles. B6/lpr-p2x7KO mice accumulated high numbers of FasL-expressing B220+ DN T cells of CD45RBhighCD44high effector/memory CD8+ T-cell origin and developed severe lupus, characterized by leukocyte infiltration into the tissues, high levels of IgG anti-dsDNA and rheumatoid factor autoantibodies, and marked cytokine network dysregulation. B6/lpr-p2x7KO mice also exhibited a considerably reduced lifespan. P2X7 is therefore a novel regulator of T-cell homeostasis, of which cooperation with Fas is critical to prevent lymphoaccumulation and autoimmunity.


Subject(s)
Receptors, Purinergic P2X7 , Rheumatoid Factor , Animals , Autoantibodies , Homeostasis , Immunoglobulin G , Mice , Mice, Inbred C57BL , Mice, Inbred MRL lpr , Receptors, Purinergic P2X7/genetics
7.
Biomed J ; 44(2): 112-114, 2021 04.
Article in English | MEDLINE | ID: mdl-33985926

ABSTRACT

This special issue contains four review articles that analyze the development and biology of innate lymphoid cells (ILCs), which are the most recently-discovered group of innate immune cells. This unique group of lymphoid cells lacks the RAG gene and consequently does not express B cell nor T cell antigen-specific receptors. They are abundant at mucosal surfaces, where they play a role in immunity and homeostasis. The ILCs are the focus of intensive research efforts to understand their development and function.


Subject(s)
B-Lymphocytes , T-Lymphocytes , Cytokines , Immunity, Innate
8.
Biomed J ; 44(4): 383-387, 2021 08.
Article in English | MEDLINE | ID: mdl-34438083

ABSTRACT

This special issue contains four review articles that describe advances in analysis of mutations responsible for the autoimmune lymphoproliferative syndrome (ALPS). This disease is triggered by a family of mutations in genes involved in the extrinsic apoptotic pathway such as FAS, FASL and CASP10. Advances in sequencing technology have enabled extended genetic testing of patients with various defects in alternative biological have pathways that can cause ALPS-like syndromes. Various gene mutations were identified which affect the CTLA-4 immune checkpoint, the STAT3 pathway and the RAS/MAPK pathway. Tips gleaned from analyses of the different gene mutations involved in ALPS and ALPS-like syndromes are contributing to a better understanding of their functional consequences. Genetic diagnoses of the disease should help us to identify specific therapeutic targets and design personalized treatment for each patient.


Subject(s)
Autoimmune Lymphoproliferative Syndrome , Apoptosis , Humans , Mutation/genetics , fas Receptor/genetics
9.
Front Immunol ; 12: 645834, 2021.
Article in English | MEDLINE | ID: mdl-33897694

ABSTRACT

Extracellular nucleotides are important mediators of activation, triggering various responses through plasma membrane P2 and P1 receptors. P2 receptors are further subdivided into ionotropic P2X receptors and G protein-coupled P2Y receptors. P2X4 is an ATP-gated cation channel broadly expressed in most tissues of the body. Within the P2X family, P2X4 has a unique subcellular distribution, being preferentially localized in lysosomes. In these organelles, high ATP concentrations do not trigger P2X4 because of the low pH. However, when the pH increases to 7.4, P2X4 can be stimulated by intra-lysosomal ATP, which is in its active, tetra-anionic form. Elucidation of P2X4, P2X3 and P2X7 structures has shed some light on the functional differences between these purinergic receptors. The potential interaction between P2X4 and P2X7 has been extensively studied. Despite intensive effort, it has not been possible yet to determine whether P2X4 and P2X7 interact as heterotrimers or homotrimers at the plasma membrane. However, several publications have shown that functional interactions between P2X4 and P2X7 do occur. Importantly, these studies indicate that P2X4 potentiates P2X7-dependent activation of inflammasomes, leading to increased release of IL-1ß and IL-18. The role of P2X4 in various diseases could be beneficial or deleterious even though the pathophysiological mechanisms involved are still poorly defined. However, in diseases whose physiopathology involves activation of the NLRP3 inflammasome, P2X4 was found to exacerbate severity of disease. The recent production of monoclonal antibodies specific for the human and mouse P2X4, some of which are endowed with agonist or antagonist properties, raises the possibility that they could be used therapeutically. Analysis of single nucleotide polymorphisms of the human P2RX4 gene has uncovered the association of P2RX4 gene variants with susceptibility to several human diseases.


Subject(s)
Receptors, Purinergic P2X4/chemistry , Receptors, Purinergic P2X4/physiology , Animals , Antibodies, Monoclonal/pharmacology , Cell Degranulation , Encephalomyelitis, Autoimmune, Experimental/etiology , Ethanol/pharmacology , Humans , Inflammasomes/physiology , Inflammation/etiology , Mast Cells/physiology , Purinergic P2X Receptor Antagonists/pharmacology , Receptors, Antigen, T-Cell/physiology , Receptors, Purinergic P2X4/genetics , Receptors, Purinergic P2X7/chemistry , Receptors, Purinergic P2X7/physiology
10.
Front Immunol ; 11: 113, 2020.
Article in English | MEDLINE | ID: mdl-32117264

ABSTRACT

P2X purinergic receptors are extracellular ATP-gated ion channel receptors present on the cell plasma membrane. P2X receptors have been found in Metazoa, fungi, amoebas, and in plants. In mammals, P2X7 is expressed by a large number of cell types and is involved in inflammation and immunity. Remarkably, P2X7 does not desensitize as other P2X do, a feature linked to a "C-cysteine anchor" intra-cytoplasmic motif encoded by exon 11. Another specific feature of P2X7 is its C-terminal cytoplasmic ballast domain (exon 13) which contains a zinc (Zn) coordinating cysteine motif and a GDP-binding region. To determine the origin of P2X7, we analyzed and compared sequences and protein motifs of the C-terminal intra-cytoplasmic region across all main groups of Metazoa. We identified proteins with typical ballast domains, sharing a remarkably conserved Zn-coordinating cysteine motif. Apart from vertebrates, these ballast domains were not associated with a typical P2X architecture. These results strongly suggest that P2X7 resulted from the fusion of a P2X gene, highly similar to P2X4, with an exon encoding a ballast domain. Our work brings new evidence on the origin of the P2X7 purinergic receptor and identifies the Zn-coordinating cysteine domain as the fundamental feature of the ancient ballast fold.


Subject(s)
Amino Acid Motifs/genetics , Receptors, Purinergic P2X7/genetics , Animals , Biological Evolution , Databases, Genetic , Humans , Phylogeny , Rats , Receptors, Purinergic P2X , Receptors, Purinergic P2X4/genetics , Sequence Alignment , Vertebrates
11.
J Neurochem ; 109(3): 846-57, 2009 May.
Article in English | MEDLINE | ID: mdl-19250337

ABSTRACT

Neural progenitor cells (NPCs) are capable of self-renewal and differentiation into neurons, astrocytes and oligodendrocytes, and have been used to treat several animal models of CNS disorders. In the present study, we show that the P2X7 purinergic receptor (P2X7R) is present on NPCs. In NPCs, P2X7R activation by the agonists extracellular ATP or benzoyl ATP triggers opening of a non-selective cationic channel. Prolonged activation of P2X7R with these nucleotides leads to caspase independent death of NPCs. P2X7R ligation induces NPC lysis/necrosis demonstrated by cell membrane disruption accompanied with loss of mitochondrial membrane potential. In most cells that express P2X7R, sustained stimulation with ATP leads to the formation of a non-selective pore allowing the entry of solutes up to 900 Da, which are reportedly involved in P2X7R-mediated cell lysis. Surprisingly, activation of P2X7R in NPCs causes cell death in the absence of pore formation. Our data support the notion that high levels of extracellular ATP in inflammatory CNS lesions may delay the successful graft of NPCs used to replace cells and repair CNS damage.


Subject(s)
Adenosine Triphosphate/pharmacology , Cell Differentiation/drug effects , Embryonic Stem Cells/drug effects , Neurons/drug effects , Receptors, Purinergic P2/metabolism , Adenosine Triphosphate/analogs & derivatives , Animals , Calcium/metabolism , Caspases/metabolism , Cell Death/drug effects , Cell Differentiation/physiology , Cells, Cultured , Chelating Agents/pharmacology , Corpus Striatum/cytology , Egtazic Acid/analogs & derivatives , Egtazic Acid/pharmacology , Embryo, Mammalian , Enzyme Inhibitors/pharmacology , Extracellular Fluid/drug effects , L-Lactate Dehydrogenase/metabolism , Membrane Potential, Mitochondrial/drug effects , Mice , Mice, Inbred C57BL , Mice, Knockout , Necrosis/metabolism , Necrosis/pathology , Receptors, Purinergic P2/deficiency , Receptors, Purinergic P2X7 , Staurosporine/pharmacology , Tetrazolium Salts , Thiazoles , Time Factors
12.
Front Cell Neurosci ; 13: 401, 2019.
Article in English | MEDLINE | ID: mdl-31551714

ABSTRACT

The purinergic receptor P2X7 is expressed in neural and immune cells known to be involved in neurological diseases. Its ligand, ATP, is a signaling molecule that can act as a neurotransmitter in physiological conditions or as a danger signal when released in high amount by damaged/dying cells or activated glial cells. Thus, ATP is a danger-associated molecular pattern. Binding of ATP by P2X7 leads to the activation of different biochemical pathways, depending on the physiological or pathological environment. The aim of this review is to discuss various functions of P2X7 in the immune and central nervous systems. We present evidence that P2X7 may have a detrimental or beneficial role in the nervous system, in the context of neurological pathologies: epilepsy, Alzheimer's disease, multiple sclerosis, amyotrophic lateral sclerosis, age-related macular degeneration and cerebral artery occlusion.

13.
Front Immunol ; 10: 2074, 2019.
Article in English | MEDLINE | ID: mdl-31552031

ABSTRACT

Extracellular nucleotides are important mediators of cell activation and trigger multiple responses via membrane receptors known as purinergic receptors (P2). P2X receptors are ligand-gated ion channels, activated by extracellular ATP. P2X4 is one of the most sensitive purinergic receptors, that is typically expressed by neurons, microglia, and some epithelial and endothelial cells. P2X4 mediates neuropathic pain via brain-derived neurotrophic factor and is also involved in inflammation in response to high ATP release. It is therefore involved in multiple inflammatory pathologies as well as neurodegenerative diseases. We have produced monoclonal antibodies (mAb) directed against this important human P2X4 receptor. Focusing on two mAbs, we showed that they also recognize mouse and rat P2X4. We demonstrated that these mAbs can be used in flow cytometry, immunoprecipitation, and immunohistochemistry, but not in Western blot assays, indicating that they target conformational epitopes. We also characterized the expression of P2X4 receptor on mouse and human peripheral blood lymphocytes (PBL). We showed that P2X4 is expressed at the surface of several leukocyte cell types, with the highest expression level on eosinophils, making them potentially sensitive to adenosine triphosphate (ATP). P2X4 is expressed by leucocytes, in human and mouse, with a significant gender difference, males having higher surface expression levels than females. Our findings reveal that PBL express significant levels of P2X4 receptor, and suggest an important role of this receptor in leukocyte activation by ATP, particularly in P2X4high expressing eosinophils.


Subject(s)
Eosinophils/immunology , Eosinophils/metabolism , Gene Expression , Receptors, Purinergic P2X4/genetics , Animals , Astrocytoma/genetics , Astrocytoma/metabolism , Biomarkers , Cell Line , Female , Glioma/genetics , Glioma/metabolism , Humans , Immunophenotyping , Leukocytes/immunology , Leukocytes/metabolism , Leukocytes/pathology , Male , Mice , Microglia/immunology , Microglia/metabolism , Receptors, Purinergic P2X4/metabolism
14.
Front Immunol ; 9: 360, 2018.
Article in English | MEDLINE | ID: mdl-29535730

ABSTRACT

A previous report has shown that regulatory T cells (Treg) were markedly more sensitive to adenosine-5'-triphosphate (ATP) than conventional T cells (Tconv). Another one has shown that Tregs and CD45RBlow Tconvs, but not CD45RBhigh Tconvs, displayed similar high sensitivity to ATP. We have previously reported that CD45RBlow Tconvs expressing B220/CD45RABC molecules in a pre-apoptotic stage are resistant to ATP stimulation due to the loss of P2X7 receptor (P2X7R) membrane expression. To gain a clearer picture on T-cell sensitivity to ATP, we have quantified four different cellular activities triggered by ATP in mouse T cells at different stages of activation/differentiation, in correlation with levels of P2X7R membrane expression. P2X7R expression significantly increases on Tconvs during differentiation from naive CD45RBhighCD44low to effector/memory CD45RBlowCD44high stage. Maximum levels of upregulation are reached on recently activated CD69+ naive and memory Tconvs. Ectonucleotidases CD39 and CD73 expression levels increase in parallel with those of P2X7R. Recently activated CD69+ CD45RBhighCD44low Tconvs, although expressing high levels of P2X7R, fail to cleave homing receptor CD62L after ATP treatment, but efficiently form pores and externalize phosphatidylserine (PS). In contrast, naive CD45RBhighCD44low Tconvs cleave CD62L with high efficiency although they express a lower level of P2X7, thus suggesting that P2X7R levels are not a limiting factor for signaling ATP-induced cellular responses. Contrary to common assumption, P2X7R-mediated cellular activities in mouse Tconvs are not triggered in an all-or-none manner, but depend on their stage of activation/differentiation. Compared to CD45RBlow Tconvs, CD45RBlowFoxp3+ Tregs show significantly higher levels of P2X7R membrane expression and of sensitivity to ATP as evidenced by their high levels of CD62L shedding, pore formation and PS externalization observed after ATP treatment. In summary, the different abilities of ATP-treated Tconvs to form pore or cleave CD62L depending on their activation and differentiation state suggests that P2X7R signaling varies according to the physiological role of T convs during antigen activation in secondary lymphoid organs or trafficking to inflammatory sites.


Subject(s)
Pore Forming Cytotoxic Proteins/metabolism , Receptors, Purinergic P2X7/metabolism , T-Lymphocytes, Regulatory/immunology , Adenosine Triphosphate/immunology , Animals , Cell Differentiation , Cell Movement , Flow Cytometry , Forkhead Transcription Factors/genetics , Gene Expression Regulation , Hyaluronan Receptors/metabolism , Immunity, Cellular , Immunophenotyping , Leukocyte Common Antigens/metabolism , Lymphocyte Activation , Mice , Mice, Inbred C57BL , Mice, Knockout , Receptors, Purinergic P2X7/genetics
15.
Mol Immunol ; 43(11): 1846-54, 2006 Apr.
Article in English | MEDLINE | ID: mdl-16376427

ABSTRACT

Cyclosporin-A and FK506 block the calcineurin activity preventing the transcription of genes sharing NFAT-like binding sequences in their promoter region. We presently show that activation of murine T-cells in presence of these immunosuppressors results in the up-regulation of the synaptotagmin-like 2 gene. However, of the four known isoforms, only mRNAs encoding the a and b isoforms accumulate. Two previously undected isoforms, each characterized by the retention of an intron, were found. The first, Slp2-e, includes exon 8, intron 8 and exon 9. The second, Slp2-f, is composed of exon 7, intron 7 and exon 8. Slp2-f has an open reading frame coding for a putative protein of 1229 amino acids sharing 47% identities with the human breast-associated antigen, SGA-72 M. In addition to the well-documented modulation of gene transcription, the two immunosuppressors also play a role in the choice of alternative splice sites on murine Slp2 pre-mRNA.


Subject(s)
Alternative Splicing/drug effects , Cyclosporine/pharmacology , Gene Expression Regulation , Membrane Proteins/genetics , RNA Splice Sites/genetics , T-Lymphocytes/drug effects , Tacrolimus/pharmacology , Alternative Splicing/genetics , Amino Acid Sequence , Animals , Base Sequence , Calcineurin Inhibitors , Cells, Cultured , Exons/genetics , Genome/genetics , Introns/genetics , Lymphocyte Activation/drug effects , Membrane Proteins/chemistry , Membrane Proteins/metabolism , Mice , Molecular Sequence Data , Open Reading Frames/genetics , Protein Isoforms/chemistry , Protein Isoforms/genetics , Protein Isoforms/metabolism , RNA, Messenger/genetics , RNA, Messenger/metabolism , Sequence Homology , T-Lymphocytes/metabolism
16.
Microbes Infect ; 18(2): 93-101, 2016 Feb.
Article in English | MEDLINE | ID: mdl-26546965

ABSTRACT

Inflammasomes are intracellular protein complexes that sense microbial components and damage of infected cells. Following activation by molecules released by pathogens or injured cells, inflammasomes activate caspase-1, allowing secretion of the pro-inflammatory cytokines IL-1ß and IL-18 from innate immune cells. Inflammasomes are also expressed in epithelial cells, where their function has attracted less attention. Nonetheless, depending on the tissue, epithelial inflammasomes can mediate inflammation, wound healing, and pain sensitivity. We review here recent findings on inflammasomes found in epithelial tissues, highlighting the importance of these protein complexes in the response of epithelial tissues to microbial infections.


Subject(s)
Epithelial Cells/physiology , Infections/immunology , Inflammasomes/metabolism , Animals , Humans
17.
Microbes Infect ; 4(8): 821-7, 2002 Jul.
Article in English | MEDLINE | ID: mdl-12270729

ABSTRACT

Apoptosis plays a major role in the development of pathogenesis due to a number of microbial infections. Epithelial cells have been previously shown to die through apoptosis during in vitro infection by the Apicomplexan parasite Cryptosporidium parvum. We now test the possibility that Fas (APO-1/CD95)-dependent apoptosis of uninfected cells, due to enhanced expression of the Fas ligand (FasL) on infected cells, may contribute to the pathology of cryptosporidiosis. Expression of the FasL increased by a large amount on the surface of intestinal epithelial cells infected with C. parvum, and the increase was limited exclusively to infected cells. In addition, a significant increase in FasL expression was observed in epithelial cells from the small intestine of mice infected with C. parvum. Finally, whereas wild-type mice depleted of CD4(+) lymphocytes lost weight during C. parvum infection, CD4(+) cell-depleted lpr mice (deficient in Fas function) infected with C. parvum gained weight at the same rate as undepleted wild-type or lpr mice. These results suggest that bystander Fas-dependent apoptosis of uninfected epithelial cells may exacerbate the weight loss associated with cryptosporidiosis.


Subject(s)
Apoptosis , Body Weight , Cryptosporidiosis/pathology , Cryptosporidiosis/physiopathology , Cryptosporidium parvum , Membrane Glycoproteins/metabolism , Animals , CD4-Positive T-Lymphocytes/immunology , Cell Line , Cryptosporidiosis/genetics , Cryptosporidiosis/metabolism , Fas Ligand Protein , Female , Gene Expression , Membrane Glycoproteins/genetics , Mice , Mice, Inbred MRL lpr , Mice, Knockout , Weight Loss
19.
Microbes Infect ; 14(14): 1254-62, 2012 Nov.
Article in English | MEDLINE | ID: mdl-22909902

ABSTRACT

Immune cells express receptors for extracellular nucleotides named P2 receptors. P2 receptors transduce signals delivered by nucleotides present in the extracellular environment. Accruing evidence shows that purinergic signalling has a profound effect on multiple immune cell responses such as T lymphocyte proliferation, chemotaxis, cytokine release, phagocytosis, Ag presentation and cytotoxicity. This makes P2 receptors an attractive target for the therapy of immuno-mediated disease and cancer.


Subject(s)
Receptors, Purinergic P2/immunology , Animals , Humans , Inflammasomes/immunology , Signal Transduction/immunology
20.
PLoS One ; 7(12): e52161, 2012.
Article in English | MEDLINE | ID: mdl-23284917

ABSTRACT

Lupus is a chronic inflammatory autoimmune disease influenced by multiple genetic loci including Fas Ligand (FasL) and P2X7 receptor (P2X7R). The Fas/Fas Ligand apoptotic pathway is critical for immune homeostasis and peripheral tolerance. Normal effector T lymphocytes up-regulate the transmembrane tyrosine phosphatase B220 before undergoing apoptosis. Fas-deficient MRL/lpr mice (lpr mutation) exhibit lupus and lymphoproliferative syndromes due to the massive accumulation of B220(+) CD4(-)CD8(-) (DN) T lymphocytes. The precise ontogeny of B220(+) DN T cells is unknown. B220(+) DN T lymphocytes could be derived from effector CD4(+) and CD8(+) T lymphocytes, which have not undergone activation-induced cell death due to inactivation of Fas, or from a special cell lineage. P2X7R is an extracellular ATP-gated cell membrane receptor involved in the release of proinflammatory cytokines and TNFR1/Fas-independent cell death. P2X7R also regulate early signaling events involved in T-cell activation. We show herein that MRL/lpr mice carry a P2X7R allele, which confers a high sensitivity to ATP. However, during aging, the MRL/lpr T-cell population exhibits a drastically reduced sensitivity to ATP- or NAD-mediated stimulation of P2X7R, which parallels the increase in B220(+) DN T-cell numbers in lymphoid organs. Importantly, we found that this B220(+) DN T-cell subpopulation has a defect in P2X7R-mediated responses. The few B220(+) T cells observed in normal MRL(+/+) and C57BL/6 mice are also resistant to ATP or NAD treatment. Unexpectedly, while P2X7R mRNA and proteins are present inside of B220(+) T cells, P2X7R are undetectable on the plasma membrane of these T cells. Our results prompt the conclusion that cell surface expression of B220 strongly correlates with the negative regulation of the P2X7R pathway in T cells.


Subject(s)
Cell Membrane/metabolism , Receptors, Purinergic P2X7/metabolism , Adenosine Triphosphate/pharmacology , Animals , Blotting, Western , CD4 Antigens/drug effects , CD4 Antigens/metabolism , CD8 Antigens/drug effects , CD8 Antigens/metabolism , Cell Membrane/drug effects , Cells, Cultured , Lymphocyte Activation/drug effects , Mice , Mice, Inbred MRL lpr , Mice, Mutant Strains , NAD/pharmacology , Real-Time Polymerase Chain Reaction , Receptors, Purinergic P2X7/genetics , Signal Transduction/drug effects
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