RESUMEN
Infertility represents a growing burden worldwide, with one in seven couples presenting difficulties conceiving. Among these, 10-15% of the men have idiopathic infertility that does not correlate with any defect in the classical sperm parameters measured. In the present study, we used a mouse model to investigate the effects of maternal undernutrition on fertility in male progeny. Our results indicate that mothers fed on a low-protein diet during gestation and lactation produce male offspring with normal sperm morphology, concentration, and motility but exhibiting an overall decrease of fertility when they reach adulthood. Particularly, in contrast to control, sperm from these offspring show a remarkable lower capacity to fertilize oocytes when copulation occurs early in the estrus cycle relative to ovulation, due to an altered sperm capacitation. Our data demonstrate for the first time that maternal nutritional stress can have long-term consequences on the reproductive health of male progeny by affecting sperm physiology, especially capacitation, with no observable impact on spermatogenesis and classical quantitative and qualitative sperm parameters. Moreover, our experimental model could be of major interest to study, explain, and ultimately treat certain categories of infertilities.
Asunto(s)
Infertilidad Masculina , Desnutrición , Adulto , Animales , Femenino , Fertilidad , Humanos , Infertilidad Masculina/etiología , Lactancia , Masculino , Desnutrición/complicaciones , Ratones , Embarazo , Capacitación Espermática , Motilidad Espermática , Espermatozoides/fisiologíaRESUMEN
Chronic treatment with acetaminophen (APAP) induces cysteine (Cys) and glutathione (GSH) deficiency which leads to adverse metabolic effects including muscle atrophy. Mammalian cells respond to essential amino acid deprivation through the phosphorylation of the eukaryotic translation initiation factor 2α (eIF2α). Phosphorylated eIF2α leads to the recruitment of activating transcription factor 4 (ATF4) to specific CCAAT/enhancer-binding protein-ATF response element (CARE) located in the promoters of target genes. Our purpose was to study the activation of the eIF2α-ATF4 pathway in response to APAP-induced Cys deficiency, as well as the potential contribution of the eIF2α kinase GCN2 and the effect of dietary supplementation with Cys. Our results showed that chronic treatment with APAP activated both GCN2 and PERK eIF2α kinases and downstream target genes in the liver. Activation of the eIF2α-ATF4 pathway in skeletal muscle was accompanied by muscle atrophy even in the absence of GCN2. The dietary supplementation with cysteine reversed APAP-induced decreases in plasma-free Cys, liver GSH, muscle mass, and muscle GSH. Our new findings demonstrate that dietary Cys supplementation also reversed the APAP-induced activation of GCN2 and PERK and downstream ATF4-target genes in the liver.
Asunto(s)
Factor de Transcripción Activador 4 , Factor 2 Eucariótico de Iniciación , Acetaminofén/efectos adversos , Factor de Transcripción Activador 4/genética , Factor de Transcripción Activador 4/metabolismo , Animales , Cisteína/metabolismo , Suplementos Dietéticos , Factor 2 Eucariótico de Iniciación/metabolismo , Glutatión/metabolismo , Mamíferos/metabolismo , Atrofia Muscular/inducido químicamente , Fosforilación , eIF-2 Quinasa/genética , eIF-2 Quinasa/metabolismoRESUMEN
In response to different environmental stresses, eIF2α phosphorylation represses global translation coincident with preferential translation of ATF4, a master regulator controlling the transcription of key genes essential for adaptative functions. Here, we establish that the eIF2α/ATF4 pathway directs an autophagy gene transcriptional program in response to amino acid starvation or endoplasmic reticulum stress. The eIF2α-kinases GCN2 and PERK and the transcription factors ATF4 and CHOP are also required to increase the transcription of a set of genes implicated in the formation, elongation and function of the autophagosome. We also identify three classes of autophagy genes according to their dependence on ATF4 and CHOP and the binding of these factors to specific promoter cis elements. Furthermore, different combinations of CHOP and ATF4 bindings to target promoters allow the trigger of a differential transcriptional response according to the stress intensity. Overall, this study reveals a novel regulatory role of the eIF2α-ATF4 pathway in the fine-tuning of the autophagy gene transcription program in response to stresses.
Asunto(s)
Factor de Transcripción Activador 4/metabolismo , Autofagia/genética , Estrés del Retículo Endoplásmico/genética , Factor 2 Eucariótico de Iniciación/metabolismo , Activación Transcripcional , Proteínas Adaptadoras Transductoras de Señales/biosíntesis , Proteínas Adaptadoras Transductoras de Señales/genética , Aminoácidos/metabolismo , Animales , Células Cultivadas , Proteínas de Choque Térmico/biosíntesis , Proteínas de Choque Térmico/genética , Ratones , Proteínas Serina-Treonina Quinasas/metabolismo , Elementos de Respuesta , Proteína Sequestosoma-1 , Factor de Transcripción CHOP/metabolismo , Regulación hacia Arriba , eIF-2 Quinasa/metabolismoRESUMEN
T cell therapy strategies, from allogeneic stem cell transplantation toward genetically-modified T cells infusion, develop powerful anti-tumor effects but are often accompanied by side effects and their efficacy remains sometimes to be improved. It therefore appears important to provide a flexible and easily reversible gene expression regulation system to control T cells activity. We developed a gene expression regulation technology that exploits the physiological GCN2-ATF4 pathway's ability to induce gene expression in T cells in response to one essential amino acid deficiency. We first demonstrated the functionality of NUTRIREG in human T cells by transient expression of reporter genes. We then validated that NUTRIREG can be used in human T cells to transiently express a therapeutic gene such as IL-10. Overall, our results represent a solid basis for the promising use of NUTRIREG to regulate transgene expression in human T cells in a reversible way, and more generally for numerous preventive or curative therapeutic possibilities in cellular immunotherapy strategies.
Asunto(s)
Enfermedad Injerto contra Huésped , Trasplante de Células Madre Hematopoyéticas , Humanos , Enfermedad Injerto contra Huésped/prevención & control , Trasplante Homólogo , Aminoácidos , Alelos , Trasplante de Células Madre Hematopoyéticas/efectos adversos , Linfocitos T , TransgenesRESUMEN
Transient environmental influences, such as perinatal nutritional stress, may induce deleterious metabolic symptoms that last for the entire life of individuals, implying that epigenetic modifications play an important role in this process. We have investigated, in mice, the consequences of maternal undernutrition during gestation and lactation on DNA methylation and expression of the leptin gene, which plays a major regulatory role in coordinating nutritional state with many aspects of mammalian biology. We show that animals born to mothers fed a low-protein-diet (F1-LPD group) have a lower body weight/adiposity and exhibit a higher food intake than animals born to mothers fed a control diet (F1-CD group). These modifications persisted throughout life and were associated with lower levels of leptin mRNA and protein in starved F1-LPD mice, emphasizing that maternal protein-undernutrition affects the balance between food intake and energy expenditure in adults. Moreover, this nutritional stress resulted in the removal of methyls at CpGs located in the promoter of leptin, causing a permanent specific modification in the dynamics of the expression of leptin, which exhibits a stronger induction in the F1-LPD than in F1-CD mice in response to a meal. This study is an example of a molecular rationale linking transient environmental influences to permanent phenotypic consequences.
Asunto(s)
Dieta , Proteínas en la Dieta/farmacología , Leptina/metabolismo , Síndrome Metabólico/etiología , Fenómenos Fisiologicos de la Nutrición Prenatal , Animales , Secuencia de Bases , Composición Corporal , Islas de CpG , Femenino , Regulación de la Expresión Génica/fisiología , Humanos , Leptina/genética , Ratones , Ratones Endogámicos BALB C , Embarazo , Regiones Promotoras Genéticas , ARN Mensajero/genética , ARN Mensajero/metabolismoRESUMEN
PURPOSE: Selection of a balanced diet has a determinant impact on human health. Individual food preferences involve socio-cultural as well as physiological factors and evolve during aging. In mammals, physiological mechanisms governing food choices appear to require the sensing of nutrient concentrations in diet. This is particularly the case for dietary amino acids that are sensed by the protein kinase GCN2. It has been reported that GCN2 is involved in the adaptive response to amino acid imbalanced diets at the level of food intake and lipid metabolism. Here, we hypothesized that GCN2 may play a role in macronutrient selection and its age-related changes. METHODS: Two groups of wild-type and GCN2 knock-out mice were subjected to a food self-selection protocol at ages 6, 12, 18 and 24 months. During each test, mice were allowed to create their own diets by selecting between three separate food sources, each containing either protein, fat or carbohydrates. RESULTS: Our results show that the absence of GCN2 had two main age-related effects. First, it exacerbated fat preference at the expense of carbohydrate consumption. Second, it prevented the increase in protein intake. CONCLUSION: These findings indicate that, in omnivores, the GCN2 ancient pathway participates in the control of food preference.
Asunto(s)
Envejecimiento/metabolismo , Conducta Animal , Carbohidratos de la Dieta/administración & dosificación , Grasas de la Dieta/administración & dosificación , Proteínas en la Dieta/administración & dosificación , Preferencias Alimentarias , Proteínas Serina-Treonina Quinasas/metabolismo , Animales , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Proteínas Serina-Treonina Quinasas/genéticaRESUMEN
Constitution of oxidative defense systems and, correspondingly, oxidative stress prevention are highly dependent on amino acid supply. In vitro, experiments have demonstrated that amino acid availability participates to the homeostasis of reactive oxygen species. However the molecular mechanisms involved in the maintenance of redox homeostasis responsive to circulating amino acid levels remain unclear. As GCN2 is a protein kinase considered to be an important sensor for amino acids availability and a potential regulator of redox homeostasis, we hypothesized that this kinase can modulate redox homeostasis in vivo, in response to an amino acid-imbalanced diet. We investigated the response of GCN2+/+ and GCN2-/- mice to a long-term (24 weeks) leucine-imbalanced diet (EDΔLeu). In order to evaluate the oxidation level in each group of mice, we determined the degree of protein oxidation in the liver. Interestingly, GCN2-/- mice exhibited an increase in protein carbonylation, a marker of oxidative stress, in response to the EDΔLeu diet. These data correlate with a decrease in hepatic GPX1 expression, a major antioxidant enzyme, and a decrease in total GPX activity in the liver. Our results suggest that GCN2 and its downstream signaling pathway have an important role in the protection against oxidative injuries induced by an amino acid-imbalanced diet, and that it can play a critical role in the prevention of oxidative damage.
Asunto(s)
Estrés Oxidativo , Proteínas Serina-Treonina Quinasas/metabolismo , Animales , Dieta , Leucina/deficiencia , Hígado/metabolismo , Ratones , Ratones Mutantes , Oxidación-Reducción , Proteínas Serina-Treonina Quinasas/genética , Especies Reactivas de Oxígeno/metabolismoRESUMEN
To insure an adequate supply of nutrients, omnivores choose among available food sources. This process is exemplified by the well-characterized innate aversion of omnivores to otherwise nutritious foods of imbalanced amino acid content. We report that brain-specific inactivation of GCN2, a ubiquitously expressed protein kinase that phosphorylates translation initiation factor 2 alpha (eIF2alpha) in response to intracellular amino acid deficiency, impairs this aversive response. GCN2 inactivation also diminishes phosphorylated eIF2alpha levels in the mouse anterior piriform cortex following consumption of an imbalanced meal. An ancient intracellular signal transduction pathway responsive to amino acid deficiency thus affects feeding behavior by activating a neuronal circuit that biases consumption against imbalanced food sources.
Asunto(s)
Aminoácidos/metabolismo , Conducta Alimentaria/fisiología , Homeostasis/fisiología , Proteínas Quinasas/fisiología , Animales , Factor 2 Eucariótico de Iniciación/metabolismo , Ratones , Ratones Noqueados , Fosforilación , Proteínas Quinasas/deficiencia , Proteínas Quinasas/metabolismo , Proteínas Serina-Treonina QuinasasRESUMEN
The transcriptional activation of CHOP (a CCAAT/enhancer-binding protein-related gene) by amino acid deprivation involves the activating transcription factor 2 (ATF2) and the activating transcription factor 4 (ATF4) binding the amino acid response element (AARE) within the promoter. Using a chromatin immunoprecipitation approach, we report that in vivo binding of phospho-ATF2 and ATF4 to CHOP AARE are associated with acetylation of histones H4 and H2B in response to amino acid starvation. A time course analysis reveals that ATF2 phosphorylation precedes histone acetylation, ATF4 binding and the increase in CHOP mRNA. We also show that ATF4 binding and histone acetylation are two independent events that are required for the CHOP induction upon amino acid starvation. Using ATF2-deficient mouse embryonic fibroblasts, we demonstrate that ATF2 is essential in the acetylation of histone H4 and H2B in vivo. The role of ATF2 on histone H4 acetylation is dependent on its binding to the AARE and can be extended to other amino acid regulated genes. Thus, ATF2 is involved in promoting the modification of the chromatin structure to enhance the transcription of a number of amino acid-regulated genes.
Asunto(s)
Factor de Transcripción Activador 2/fisiología , Aminoácidos/metabolismo , Histonas/metabolismo , Factor de Transcripción CHOP/genética , Activación Transcripcional , Acetilación , Factor de Transcripción Activador 4/metabolismo , Animales , Células Cultivadas , Ratones , Fosforilación , Elementos de Respuesta , Factor de Transcripción CHOP/biosíntesisRESUMEN
When an essential amino acid is limited, a signaling cascade is triggered that leads to increased translation of the 'master regulator', activating transcription factor 4 (ATF4), and resulting in the induction of specific target genes. Binding of ATF4 to the amino acid response element (AARE) is an essential step in the transcriptional activation of CHOP (a CCAAT/enhancer-binding protein-related gene) by amino acid deprivation. We set out to identify proteins that interact with ATF4 and that play a role in the transcriptional activation of CHOP. Using a tandem affinity purification (TAP) tag approach, we identified p300/CBP-associated factor (PCAF) as a novel interaction partner of ATF4 in leucine-starved cells. We show that the N-terminal region of ATF4 is required for a direct interaction with PCAF and demonstrate that PCAF is involved in the full transcriptional response of CHOP by amino acid starvation. Chromatin immunoprecipitation analysis revealed that PCAF is engaged on the CHOP AARE in response to amino acid starvation and that ATF4 is essential for its recruitment. We also show that PCAF stimulates ATF4-driven transcription via its histone acetyltransferase domain. Thus PCAF acts as a coactivator of ATF4 and is involved in the enhancement of CHOP transcription following amino acid starvation.
Asunto(s)
Factor de Transcripción Activador 4/metabolismo , Aminoácidos/fisiología , Factor de Transcripción CHOP/genética , Activación Transcripcional , Factores de Transcripción p300-CBP/metabolismo , Factor de Transcripción Activador 4/química , Factor de Transcripción Activador 4/fisiología , Animales , Sitios de Unión , Línea Celular , Células Cultivadas , Células HeLa , Humanos , Leucina/fisiología , Ratones , Estructura Terciaria de Proteína , Elementos de Respuesta , Factores de Transcripción p300-CBP/química , Factores de Transcripción p300-CBP/genéticaRESUMEN
In order to automatically process qPCR raw data, we present the tool "Do my qPCR calculation". We offer a website to automatically calculate the data normalization and represent the different samples graphically in an Excel file. This tool is also available on Github for installation and local use with or without web interface.
RESUMEN
The transcriptional activation of CHOP (C/EBP-homologous protein) by amino acid deprivation involves ATF2 and ATF4 binding at the amino acid response element within the promoter. In this report, we investigate the role of JDP2 (Jun Dimerization Protein 2) in the amino acid control of CHOP transcription following amino acid starvation. Our results show that JDP2 binds to the CHOP AARE in unstimulated cells and that its binding decreases following amino acid starvation. We demonstrate that JDP2 acts as a repressor and suggest that it could be functionally associated with HDAC3 to inhibit CHOP transcription.
Asunto(s)
Regulación de la Expresión Génica , Proteínas Represoras/fisiología , Factor de Transcripción CHOP/genética , Transcripción Genética , Dimerización , Genes Reporteros , Células HeLa , Histona Desacetilasas/metabolismo , Humanos , Leucina/metabolismo , Luciferasas/genéticaRESUMEN
The uncontrolled growth of tumor can lead to the formation of area deprived in nutrients. Due to their high genetic instability, tumor cells can adapt and develop resistance to this pro-apoptotic environment. Among the resistance mechanisms, those involved in the resistance to long-term amino acid restriction are not elucidated. A long-term amino acid restriction is particularly deleterious since nine of them cannot be synthetized by the cells. In order to determine how cancer cells face a long-term amino acid deprivation, we developed a cell model selected for its capacity to resist a long-term amino acid limitation. We exerted a selection pressure on mouse embryonic fibroblast to isolate clones able to survive with low amino acid concentration. The study of several clones revealed an alteration of the eiF2α/ATF4 pathway. Compared to the parental cells, the clones exhibited a decreased expression of the transcription factor ATF4 and its target genes. Likewise, the knock-down of ATF4 in parental cells renders them resistant to amino acid deprivation. Moreover, this association between a low level of ATF4 protein and the resistance to amino acid deprivation was also observed in the cancer cell line BxPC-3. This resistance was abolished when ATF4 was overexpressed. Therefore, decreasing ATF4 expression may be one important mechanism for cancer cells to survive under prolonged amino acid deprivation.
Asunto(s)
Factor de Transcripción Activador 4/genética , Aminoácidos/metabolismo , Regulación Neoplásica de la Expresión Génica , Factor de Transcripción Activador 4/metabolismo , Animales , Apoptosis/genética , Línea Celular , Proliferación Celular/efectos de los fármacos , Perfilación de la Expresión Génica , Humanos , Diana Mecanicista del Complejo 1 de la Rapamicina/metabolismo , Ratones , Modelos Biológicos , Neoplasias/genética , Neoplasias/metabolismo , Unión Proteica , Proteínas Serina-Treonina Quinasas/metabolismo , Interferencia de ARN , Transducción de SeñalRESUMEN
It has been reported that breast-feeding more than 6 months strongly decreases the risk of allergy, diabetes, obesity, and hypertension in humans. In order to understand the mechanisms responsible for this benefit, it is important to evaluate precisely the composition of maternal milk, especially in response to environmental cues. Mouse models offer a unique opportunity to study the impact of maternal milk composition on the development and health of offspring. Oxytocin injection of the dam is usually used to stimulate milk ejection; however, exogenous oxytocin might have deleterious effects under some experimental conditions by modifying milk content as well as the physiology and behavior of the dam. Taking advantage of the natural stimulation of the mammary gland that occurs after the reunion of a dam that has been separated from her pups, we developed a new procedure to collect mouse milk without the injection of oxytocin. This method is easy to use, low-cost ,and non-invasive. Moreover, it provides a sufficient amount of milk for use in a wide range of biological analyses.
Asunto(s)
Lactancia Materna , Glándulas Mamarias Animales/fisiología , Eyección Láctea/fisiología , Leche , Animales , Mama/metabolismo , Mama/fisiología , Femenino , Humanos , Ratones , Oxitocina/farmacologíaRESUMEN
It is well known that the GCN2 and mTORC1 signaling pathways are regulated by amino acids and share common functions, in particular the control of translation. The regulation of GCN2 activity by amino acid availability relies on the capacity of GCN2 to sense the increased levels of uncharged tRNAs upon amino acid scarcity. In contrast, despite recent progress in the understanding of the regulation of mTORC1 by amino acids, key aspects of this process remain unsolved. In particular, while leucine is well known to be a potent regulator of mTORC1, the mechanisms by which this amino acid is sensed and control mTORC1 activity are not well defined. Our data establish that GCN2 is involved in the inhibition of mTORC1 upon leucine or arginine deprivation. However, the activation of GCN2 alone is not sufficient to inhibit mTORC1 activity, indicating that leucine and arginine exert regulation via additional mechanisms. While the mechanism by which GCN2 contributes to the initial step of mTORC1 inhibition involves the phosphorylation of eIF2α, we show that it is independent of the downstream transcription factor ATF4. These data point to a novel role for GCN2 and phosphorylation of eIF2α in the control of mTORC1 by certain amino acids.
Asunto(s)
Factor de Transcripción Activador 4/metabolismo , Leucina/deficiencia , Diana Mecanicista del Complejo 1 de la Rapamicina/antagonistas & inhibidores , Proteínas Serina-Treonina Quinasas/metabolismo , Animales , Arginina/deficiencia , Embrión de Mamíferos/citología , Factor 2 Eucariótico de Iniciación/metabolismo , Fibroblastos/metabolismo , Diana Mecanicista del Complejo 1 de la Rapamicina/metabolismo , Ratones , Fosforilación , Transducción de SeñalRESUMEN
Widespread application of gene therapy will depend on the development of simple methods to regulate the expression of therapeutic genes. Here we harness an endogenous signaling pathway to regulate therapeutic gene expression through diet. The GCN2-eIF2α signaling pathway is specifically activated by deficiencies in any essential amino acid (EAA); EAA deficiency leads to rapid expression of genes regulated by ATF4-binding cis elements. We found that therapeutic genes under the control of optimized amino acid response elements (AAREs) had low basal expression and high induced expression. We applied our system to regulate the expression of TNFSF10 (TRAIL) in the context of glioma therapy and found that intermittent activation of this gene by EEA-deficient meals retained its therapeutic efficacy while abrogating its toxic effects on normal tissue. The GCN2-eIF2α pathway is expressed in many tissues, including the brain, and is highly specific to EAA deficiency. Our system may be particularly well suited for intermittent regulation of therapeutic transgenes over short or long time periods.
Asunto(s)
Aminoácidos Esenciales/administración & dosificación , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/terapia , Terapia Genética/métodos , Ligando Inductor de Apoptosis Relacionado con TNF/genética , Ligando Inductor de Apoptosis Relacionado con TNF/uso terapéutico , Administración Oral , Aminoácidos Esenciales/farmacocinética , Animales , Suplementos Dietéticos , Relación Dosis-Respuesta a Droga , Ingestión de Alimentos/genética , Regulación de la Expresión Génica/efectos de los fármacos , Regulación de la Expresión Génica/genética , Masculino , Ratones , Transgenes/genética , Resultado del TratamientoRESUMEN
In mammals, metabolic adaptations are required to overcome nutritional deprivation in amino-acids/proteins as well as episodes of malnutrition. GCN2 protein kinase, which phosphorylates the α subunit of the translation initiation factor eIF2, is a sensor of amino-acid(s) deficiencies. On one hand, this review briefly describes the main features of amino-acid metabolism. On the other hand, it describes the role of GCN2 in regulating numerous physiological functions.
Asunto(s)
Adaptación Biológica/fisiología , Aminoácidos Esenciales/administración & dosificación , Dieta , Proteínas Serina-Treonina Quinasas/fisiología , Aminoácidos , Aminoácidos Esenciales/deficiencia , Animales , Factor 2 Eucariótico de Iniciación/metabolismo , Homeostasis , Humanos , Inmunidad , Desnutrición , Plasticidad Neuronal , Estado Nutricional , Fosforilación , Transducción de Señal/fisiologíaRESUMEN
The eIF2α-ATF4 pathway is involved in cellular adaptation to stress and is dysregulated in numerous diseases. Activation of this pathway leads to phosphorylation of the α subunit of eukaryotic initiation factor 2 (eIF2α) and the recruitment of the transcription factor ATF4 (activating transcription factor 4) to specific CCAAT/enhancer binding protein (C/EBP)-ATF response elements (CAREs) located in the promoters of target genes. To monitor the spatiotemporal modulation of this pathway in living animals, we generated a novel CARE-driven luciferase mouse model (CARE-LUC). These transgenic mice enable the investigation of the eIF2α-ATF4 pathway activity in the whole organism and at the tissue and cellular levels by combining imaging, luciferase assays, and immunochemistry. Using this mouse line, we showed the tissue-specific activation pattern of this pathway in response to amino acid deficiency or endoplasmic reticulum stress and the hepatic induction of this pathway in a stress-related pathology model of liver fibrosis. The CARE-LUC mouse model represents an innovative tool to investigate the eIF2α-ATF4 axis and to develop drugs targeting this important pathway in the remediation of related pathologies.
Asunto(s)
Factor de Transcripción Activador 4/metabolismo , Factor 2 Eucariótico de Iniciación/metabolismo , Imagen Molecular , Transducción de Señal , Estrés Fisiológico , Factor de Transcripción Activador 4/genética , Animales , Factor 2 Eucariótico de Iniciación/genética , Ratones , Ratones TransgénicosRESUMEN
We previously showed that the intraperitoneal (i.p.) administration of 200mg/kg cyclophosphamide, an antitumoral agent, modified the behaviour of rats with cystitis induced by acrolein, a toxic urinary by-product of cyclophosphamide. This behaviour, (namely decreased breathing rate, closing of the eyes, and specific postures), was scored to indirectly assess the nociception elicited by the cystitis and to use this experimental model as a vesical pain model. Here we investigated the involvement of the N-methyl-D-aspartate (NMDA) receptors and thus of the excitatory amino acid system in this model. We administered dizocilpine (0.01 to 0.1mg/kg intravenously (i.v.) and 1 to 20 microg/rat intrathecally (i.t.)) and ketamine (5 and 10mg/kg i.v. and 50 to 1000 microg/rat i.t.), two non-competitive NMDA receptor antagonists that bind to the channel site, and AP-5 (0.01 to 1mg/kg i.v. and 20 to 500 microg/rat i.t), a competitive antagonist that binds to the glutamate site. Whichever the route of administration (i.v. or i.t.), dizocilpine dose-relatedly reduced the behavioural disorders induced by cyclophosphamide. Systemic ketamine also dose-dependently, though transiently, reduced the effects of cyclophosphamide, but ketamine i.t. and AP-5 i.v. and i.t. did not induce any reduction of these effects.These results (i) demonstrate that in the cyclophosphamide-induced vesical pain model NMDA receptors are involved in the nociception, as shown by the effects of dizocilpine and systemic ketamine, (ii) reveal marked differences in the data obtained with various NMDA receptor antagonists, possibly due to their physicochemical properties, to the animal pain model used, to the noxious stimulus applied or to any combination of these factors.
Asunto(s)
Ciclofosfamida/efectos adversos , Cistitis/complicaciones , Dolor/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Acroleína/efectos adversos , Animales , Antineoplásicos Alquilantes/efectos adversos , Conducta Animal , Cistitis/inducido químicamente , Cistitis/metabolismo , Maleato de Dizocilpina/farmacología , Relación Dosis-Respuesta a Droga , Inyecciones Intravenosas , Inyecciones Espinales , Ketamina/farmacología , Masculino , Modelos Animales , Dolor/tratamiento farmacológico , Dolor/etiología , Ratas , Ratas Sprague-Dawley , Receptores de N-Metil-D-Aspartato/antagonistas & inhibidoresRESUMEN
CHOP encodes a ubiquitous transcription factor that is one of the most important components in the network of stress-inducible transcription. In particular, this factor is known to mediate cell death in response to stress. The focus of this work is to study its pivotal role in the control of cell viability according to the duration of a stress like amino acid starvation. We show that during the first 6h of starvation, CHOP upregulates a number of autophagy genes but is not involved in the first steps of the autophagic process. By contrast, when the amino acid starvation is prolonged (16-48h), we demonstrated that CHOP has a dual role in both inducing apoptosis and limiting autophagy through the transcriptional control of specific target genes. Overall, this study reveals a novel regulatory role for CHOP in the crosstalk between autophagy and apoptosis in response to stress.