ABSTRACT
Organization of immune responses requires exchange of information between cells. This is achieved through either direct cell-cell contacts and establishment of temporary synapses or the release of soluble factors, such as cytokines and chemokines. Here we show a novel form of cell-to-cell communication based on adenosine triphosphate (ATP). ATP released by stimulated T cells induces P2X4/P2X7-mediated calcium waves in the neighboring lymphocytes. Our data obtained in lymph node slices suggest that, during T-cell priming, ATP acts as a paracrine messenger to reduce the motility of lymphocytes and that this may be relevant to allow optimal tissue scanning by T cells.
Subject(s)
Adenosine Triphosphate/metabolism , Calcium/metabolism , Cell Movement/immunology , Models, Immunological , Paracrine Communication/immunology , Paracrine Communication/physiology , T-Lymphocytes/immunology , Analysis of Variance , Animals , Humans , Lymph Nodes/metabolism , Mice , Mice, Inbred C57BL , Mice, Transgenic , Microscopy, Confocal , Real-Time Polymerase Chain Reaction , Receptors, Purinergic P2X/metabolism , T-Lymphocytes/metabolismABSTRACT
Agrin, an extracellular matrix protein belonging to the heterogeneous family of heparan sulfate proteoglycans (HSPGs), is expressed by cells of the hematopoietic system but its role in leukocyte biology is not yet clear. Here we demonstrate that agrin has a crucial, nonredundant role in myeloid cell development and functions. We have identified lineage-specific alterations that affect maturation, survival and properties of agrin-deficient monocytic cells, and occur at stages later than stem cell precursors. Our data indicate that the cell-autonomous signals delivered by agrin are sensed by macrophages through the α-DC (DG) receptor and lead to the activation of signaling pathways resulting in rearrangements of the actin cytoskeleton during the phagocytic synapse formation and phosphorylation of extracellular signal-regulated kinases (Erk 1/2). Altogether, these data identify agrin as a novel player of innate immunity.
Subject(s)
Agrin/metabolism , Myeloid Cells/cytology , Myelopoiesis , Agrin/analysis , Agrin/genetics , Animals , Cell Survival , Dystroglycans/metabolism , Extracellular Signal-Regulated MAP Kinases/metabolism , Gene Deletion , Gene Expression Regulation, Developmental , Macrophages/cytology , Macrophages/metabolism , Mice , Mice, Inbred C57BL , Monocytes/cytology , Monocytes/metabolism , Myeloid Cells/metabolism , Phagocytosis , PhosphorylationABSTRACT
Alzheimer's disease (AD) is a major clinical concern, and the search for new molecules to combat disease progression remains important. One of the major hallmarks in AD pathogenesis is the hyperphosphorylation of tau and subsequent formation of neurofibrillary tangles. Several kinases are involved in this process. Amongst them, c-Jun N-terminal kinases (JNKs) are activated in AD brains and are also associated with the development of amyloid plaques. This study was designed to investigate the contribution of JNK in tau hyperphosphorylation and whether it may represent a potential therapeutic target for the fight against AD. The specific inhibition of JNK by the cell permeable peptide D-JNKI-1 led to a reduction of p-tau at S202/T205 and S422, two established target sites of JNK, in rat neuronal cultures and in human fibroblasts cultures. Similarly, D-JNKI-1 reduced p-tau at S202/T205 in an in vivo model of AD (TgCRND8 mice). Our findings support the fundamental role of JNK in the regulation of tau hyperphosphorylation and subsequently in AD pathogenesis.
Subject(s)
Alzheimer Disease/metabolism , Cerebral Cortex/metabolism , JNK Mitogen-Activated Protein Kinases/metabolism , Neurons/metabolism , tau Proteins/metabolism , Aged , Aged, 80 and over , Alzheimer Disease/pathology , Animals , Cells, Cultured , Cerebral Cortex/drug effects , Cerebral Cortex/pathology , Female , Humans , JNK Mitogen-Activated Protein Kinases/pharmacology , Male , Middle Aged , Mitogen-Activated Protein Kinases/metabolism , Neurofibrillary Tangles/drug effects , Neurofibrillary Tangles/metabolism , Neurofibrillary Tangles/pathology , Neurons/drug effects , Neurons/pathology , Phosphorylation , RatsABSTRACT
The phosphorylation of Amyloid Precursor Protein (APP) at Thr668 plays a key role in APP metabolism that is highly relevant to AD. The c-Jun-N-terminal kinase (JNK), glycogen synthase kinase-3ß (GSK-3ß) and cyclin-dependent kinase 5 (Cdk5) can all be responsible for this phosphorylation. These kinases are activated by excitotoxic stimuli fundamental hallmarks of AD. The exposure of cortical neurons to a high dose of NMDA (100 µM) for 30'-45' led to an increase of P-APP Thr668. During NMDA stimulation APP hyperphosphorylation has to be assigned to GSK-3ß activity, since addition of L803-mts, a substrate competitive inhibitor of GSK-3ß reduced APP phosphorylation induced by NMDA. On the contrary, inhibition of JNK and Cdk5 with D-JNKI1 and Roscovitine respectively did not prevent NMDA-induced P-APP increase. These data show a tight connection, in excitotoxic conditions, between APP metabolism and the GSK-3ß signaling pathway.
ABSTRACT
Secretion of Amyloid-beta peptide (Abeta) circulating oligomers and their aggregate forms derived by processing of beta-amyloid precursor protein (APP) are a key event in Alzheimer's disease (AD). We show that phosphorylation of APP on threonine 668 may play a role in APP metabolism in H4-APP(sw) cell line, a degenerative AD model. We proved that JNK plays a fundamental role in this phosphorylation since its specific inhibition, with the JNK inhibitor peptide (D-JNKI1), induced APP degradation and prevented APP phosphorylation at T668. This results in a significant drop of betaAPPs, Abeta fragments and Abeta circulating oligomers. Moreover the D-JNKI1 treatment produced a switch in the APP metabolism, since the peptide reduced the rate of the amyloidogenic processing in favour of the non-amyloidogenic one. All together our results suggest an important link between APP metabolism and the JNK pathway and contribute to shed light on the molecular signalling pathway of this disease indicating JNK as an innovative target for AD therapy.
Subject(s)
Alzheimer Disease/metabolism , Amyloid beta-Protein Precursor/metabolism , JNK Mitogen-Activated Protein Kinases/metabolism , Receptors, Cell Surface/metabolism , Alzheimer Disease/genetics , Amyloid Precursor Protein Secretases/metabolism , Amyloid beta-Protein Precursor/genetics , Aspartic Acid Endopeptidases/metabolism , Cell Line, Tumor , Cell Survival , Enzyme-Linked Immunosorbent Assay , Fluoroimmunoassay , Humans , Immunoblotting , Immunohistochemistry , JNK Mitogen-Activated Protein Kinases/antagonists & inhibitors , MAP Kinase Signaling System , Mutation , Peptide Fragments/metabolism , Peptides/metabolism , Peptides/pharmacology , Phosphorylation , Protease Nexins , Receptors, Cell Surface/geneticsABSTRACT
Hypoxia is an established factor of neurodegeneration. Nowadays, attention is directed at understanding how alterations in the expression of stress-related signaling proteins contribute to age dependent neuronal vulnerability to injury. The purpose of this study was to investigate how Hif-1alpha, a major neuroprotective factor, and JNK signaling, a key pathway in neurodegeneration, relate to hypoxic injury in young (6DIV) and adult (12DIV) neurons. We could show that in young neurons as compared to mature ones, the protective factor Hif-1alpha is more induced while the stress protein phospho-JNK displays lower basal levels. Indeed, changes in the expression levels of these proteins correlated with increased vulnerability of adult neurons to hypoxic injury. Furthermore, we describe for the first time that treatment with the D-JNKI1, a JNK-inhibiting peptide, rescues adult hypoxic neurons from death and contributes to Hif-1alpha upregulation, probably via a direct interaction with the Hif-1alpha protein.
Subject(s)
Hypoxia-Inducible Factor 1, alpha Subunit/metabolism , JNK Mitogen-Activated Protein Kinases/metabolism , Neurons/enzymology , Neurons/pathology , Aging/pathology , Amino Acid Sequence , Animals , Cell Death , Cell Hypoxia , Humans , Hypoxia-Inducible Factor 1, alpha Subunit/chemistry , MAP Kinase Signaling System , Molecular Sequence Data , Protein Binding , Protein Structure, Secondary , Protein Structure, Tertiary , RatsSubject(s)
3' Untranslated Regions/genetics , Circadian Rhythm/genetics , Polymorphism, Single Nucleotide/genetics , Sleep Wake Disorders/pathology , Trans-Activators/genetics , Bipolar Disorder/genetics , CLOCK Proteins , Case-Control Studies , Depressive Disorder/genetics , Humans , Sleep/physiologyABSTRACT
Recently, an association between serotonin 1A receptor binding potential and self-transcendence scores at the temperament and character inventory (TCI) has been reported. We tested involvement of 5-HT(1A) gene in this trait, in a sample of 40 remitted mood disorder patients. Subjects with the 5-HT(1A)*C/C genotype showed significantly lower scores at the total self-transcendence and at the sub-scales of transpersonal identification and spiritual acceptance. Our preliminary results further support the involvement of the serotoninergic pattern in the self-transcendence character trait.
