Polimorfismo de los citocromos P-450. Importancia fisiopatológica y farmacológica

Polimorfismo de los citocromos P-450. Importancia fisiopatológica y farmacológica

Functional characterization of P2Y1 and P2X4 receptors in human neuroblastoma SK-N-MC cells

Nucleotides are important signalling molecules in both the peripheral and central nervous system. However, the in vitro study of their receptors can be hampered by the heterogeneity of primary neuronal cultures. The use of clonal neuroblastoma cell lines allows to circumvent this difficulty, so these lines are often used as a model to analyze the properties, regulation and physiological role of nucleotide receptors in neural tissues. Expression studies indicated the presence of P2Y1, P2Y6, P2Y11, P2Y13, P2X1, P2X4, P2X5, P2X6 and P2X7 proteins in SK-N-MC cells. Functional analyses showed transient [Ca2+]i increases upon application of ADP, 2-MeSADP or ADPβS. Responses to these agonists seem to be mediated by a P2Y1 receptor, as demonstrated by the almost complete blockade exerted by the P2Y1-selective antagonist MRS2179. ATP was also able to induce [Ca2+]i increases in SK-N-MC cells. Responses to ATP were partially blocked by MRS2179 and the P2X antagonist TNP-ATP, thus suggesting that ATP can interact with two different P2 receptors: a P2Y1 receptor, inhibited by MRS2179, and a TNP-ATP sensitive P2X receptor. To characterize the P2X receptor responsible for the MRS2179-resistant component of the ATP response, we analyze the effect of several P2X agonists on [Ca2+]i. Cells did not show responses to either α,β-meATP or BzATP, although [Ca2+]i increases could be observed when cells were challenged with CTP. Both the response to CTP and the MRS2179-resistant component of ATP response were potentiated by ivermectin. Such pharmacological profile is consistent with the presence of a functional P2X4 receptor in SK-N-MC cell lineLos nucleótidos son importantes moléculas señalizadoras en el sistema nervioso. El estudio in vitro de sus receptores puede verse obstaculizado por la heterogeneidad de los cultivos neuronales. El uso de líneas celulares de neuroblastoma permite eludir esta dificultad y dichas líneas se utilizan frecuentemente como un modelo con el que analizar las propiedades, regulación y función de los receptores de nucleótidos en tejidos neurales. Estudios de expresión indicaron la presencia de proteínas P2Y1, P2Y6, P2Y11, P2Y13, P2X1, P2X4, P2X5, P2X6 y P2X7 en las células SK-N-MC. Análisis funcionales mostraron incrementos transitorios de [Ca2+]i tras la aplicación de ADP, 2- MeSADP o ADPβS, respuestas que parecen estar mediadas a través un receptor P2Y1, como se pone de manifiesto por el bloqueo casi total ejercido por el antagonista selectivo P2Y1, MRS2179. El ATP también indujo incrementos de [Ca2+]i en las células SK-N-MC, siendo su respuesta parcialmente bloqueada por MRS2179 y por el antagonista P2X TNP-ATP, lo que sugiere que el ATP puede interactuar con dos receptores P2 diferentes: un receptor P2Y1, inhibido por MRS2179, y un receptor P2X sensible a TNP-ATP. Se caracterizó el receptor P2X analizando el efecto de varios agonistas en la [Ca2+]i. Ninguna célula mostró respuestas a αβ- meATP o BzATP, aunque se observaron incrementos de [Ca2+]i cuando las células fueron estimuladas con CTP. Tanto la respuesta a CTP como el componente de la respuesta a ATP resistente a MRS2179, se potenciaron en presencia de ivermectina. Todos estos datos sugieren la presencia de un receptor P2X4 funcional en las células SK-N-MCThis work was supported by research grants from Ministerio de Ciencia e Innovación (BFU2014-53654-P) and Comunidad de Madrid (S2013/ICE-2958 BRADECM

Los receptores de nucleótidos P2Y reducen la entrada de calcio inducida por despolarización en terminales sinápticos de cerebro medio de rata

Studies were carried out to determine the presence and function of P2Y receptors in synaptic terminals from rat midbrain. Immunochemical essays have shown the expression of the nucleotide P2Y2 and P2Y4 receptors. Activation of these receptors induces a reduction of the calcium entrance into the terminals, when stimulated with depolarising agents. A similar effect is produced by agonists of metabotropic receptors, such as the adenosine A1 or GABAB receptors, which are well known for its role in the presynaptic control or transmitter release. Activation of the P2Y receptors also triggers a reduction in the intrasynaptosomal cAMP concentration. Thus, these receptors seem to be negatively coupled to adenylate cyclase activity. However, we postulate that P2Y receptors are able to reduce calcium entrance into the terminals by the activation of the corresponding G protein, dissociation of the trimer and action of the âã subunits on voltage activated calcium channels.Se han llevado a cabo estudios para determinar la presencia y funcion de receptores P2Y en terminales sinapticas de cerebro medio. Ensayos imnunoquimicos han mostrado la expresion, en dichas terminales, de los receptores P2Y2 y P2Y4. La activacion de estos receptores por sus agonistas selectivos lleva a una reduccion en la entrada de calcio en las terminales, inducida por agentes despolarizantes. Este efecto es similar al que producen agonistas de otros receptores metabotropicos, como los A1 de adenosina o los GABAB, conocidos por su papel en el control presinaptico de la liberacion de neurotransmisores. La activacion de los receptores P2Y conduce asimismo a una disminucion en los niveles intrasinaptosomales de AMPc, por lo que estos receptores parecen estar acoplados negativamente a la actividad de la adenilato ciclasa. Sin embargo, se plantea como hipotesis que los receptores P2Y pudiesen actuar reduciendo la entrada de calcio en las terminales a traves de la disociacion de la proteina G a la que estan acoplados, y la posterior accion del dimero ƒÀƒÁ sobre canales de calcio dependientes de voltaje

Nucleotides in neuroregeneration and neuroprotection

AbstractBrain injury generates the release of a multitude of factors including extracellular nucleotides, which exhibit bi-functional properties and contribute to both detrimental actions in the acute phase and also protective and reparative actions in the later recovery phase to allow neuroregeneration. A promising strategy toward restoration of neuronal function is based on activation of endogenous adult neural stem/progenitor cells. The implication of purinergic signaling in stem cell biology, including regulation of proliferation, differentiation, and cell death has become evident in the last decade. In this regard, current strategies of acute transplantation of ependymal stem/progenitor cells after spinal cord injury restore altered expression of P2X4 and P2X7 receptors and improve functional locomotor recovery. The expression of both receptors is transcriptionally regulated by Sp1 factor, which plays a key role in the startup of the transcription machinery to induce regeneration-associated genes expression. Finally, general signaling pathways triggered by nucleotide receptors in neuronal populations converge on several intracellular kinases, such as PI3K/Akt, GSK3 and ERK1,2, as well as the Nrf-2/heme oxigenase-1 axis, which specifically link them to neuroprotection. In this regard, regulation of dual specificity protein phosphatases can become novel mechanism of actions for nucleotide receptors that associate them to cell homeostasis regulation.This article is part of the Special Issue entitled ‘Purines in Neurodegeneration and Neuroregeneration’

Caracterización funcional de receptores P2Y1 y P2X4 en células SK-N-MC de neuroblastoma humano

Los nucleótidos son importantes moléculas señalizadoras en el sistema nervioso. El estudio in vitro de sus receptores puede verse obstaculizado por la heterogeneidad de los cultivos neuronales. El uso de líneas celulares de neuroblastoma permite eludir esta dificultad y dichas líneas se utilizan frecuentemente como un modelo con el que analizar las propiedades, regulación y función de los receptores de nucleótidos en tejidos neurales.Estudios de expresión indicaron la presencia de proteínas P2Y1, P2Y6, P2Y11, P2Y13, P2X1, P2X4, P2X5, P2X6 y P2X7 en las células SK-N-MC. Análisis funcionales mostraron incrementos transitorios de [Ca2+]i tras la aplicación de ADP, 2-MeSADP o ADPβS, respuestas que parecen estar mediadas a través un receptor P2Y1, como se pone de manifiesto por el bloqueo casi total ejercido por el antagonista selectivo P2Y1, MRS2179. El ATP también indujo incrementos de [Ca2+]i en las células SK-N-MC, siendo su respuesta parcialmente bloqueada por MRS2179 y por el antagonista P2X TNP-ATP, lo que sugiere que el ATP puede interactuar con dos receptores P2 diferentes: un receptor P2Y1, inhibido por MRS2179, y un receptor P2X sensible a TNP-ATP. Se caracterizó el receptor P2X analizando el efecto de varios agonistas en la [Ca2+]i. Ninguna célula mostró respuestas a α,β-meATP o BzATP, aunque se observaron incrementos de [Ca2+]i cuando las células fueron estimuladas con CTP. Tanto la respuesta a CTP como el componente de la respuesta a ATP resistente a MRS2179, se potenciaron en presencia de ivermectina. Todos estos datos sugieren la presencia de un receptor P2X4 funcional en las células SK-N-MC

El transportador vesicular de nucleótidos (VNUT). Relevancia en tejidos neurales y neuroendocrinos. Nuevas perspectivas farmacológicas

Vesicular storage of neurotransmitters, which allows their subsequent exocytotic release, is essential for chemical transmission in neurons and endocrine cells. Neurotransmitter uptake to secretory vesicles is carried out by vesicular transporters, which use the electrochemical gradient of protons generated by a vacuolar proton-ATPase as transport driving force. ATP and other nucleotides and dinucleotides are relevant signaling molecules that participate in a variety of biological process. Although the active transport of nucleotides has been pharmacologically and biochemically characterized in a diversity of secretory vesicles, the protein responsible for such vesicular accumulation remained unidentified for some time. In 2008, SLC17A9, the last identified member of the SLC17 transporter family, was found to encode the vesicular nucleotide transporter (VNUT). VNUT is expressed in various ATP-secreting cells and is able to transport several nucleotides in a vesicular membrane potential- dependent fashion. VNUT knockout mice lack vesicular storage and release of ATP from neurons and neuroendocrine cells, resulting in blockage of the purinergic chemical transmission. This review summarizes the current studies on VNUT and analyzes the relevance of vesicular nucleotide transport in different cells types and tissues. The possible use of VNUT inhibitors and interference RNA to reduce VNUT gene expression for therapeutic purposes is also discussed.El almacenamiento vesicular de los neurotransmisores, que permite su subsecuente liberación exocitótica, es un proceso esencial para la transmisión química en neuronas y células endocrinas. La acumulación de los neurotransmisores en vesículas de secreción se lleva a cabo por medio de transportadores vesiculares, que utilizan el gradiente electroquímico de protones generado por una ATPasa vacuolar como fuerza impulsora del transporte. El ATP, así como otros nucleótidos y dinucleótidos, son importantes moléculas señalizadoras que intervienen en una gran variedad de procesos biológicos. Aunque el transporte activo de nucleótidos se ha caracterizado desde el punto de vista bioquímico y farmacológico en una variedad de vesículas de secreción, la proteína responsable de esta acumulación vesicular permaneció durante mucho tiempo desconocida. En 2008, se demostró que SLC17A9, el último miembro identificado de la familia de transportadores SLC17, codifica el transportador vesicular de nucleótidos (VNUT). VNUT se expresa en una variedad de células que liberan ATP y ha mostrado ser capaz de transportar varios nucleótidos de manera dependiente del potencial de membrana vesicular. Ratones deficientes en VNUT pierden la capacidad de almacenar y liberar ATP de neuronas y células neuroendocrinas, lo que resulta en un bloqueo de la transmisión química purinérgica. En esta revisión se pretende resumir los estudios llevados a cabo hasta la fecha sobre VNUT y analizar la relevancia del transporte vesicular de nucleótidos en distintos tipos celulares y tejidos. Asimismo, se discute el posible uso de inhibidores de VNUT, así como de ARNs de interferencia que reduzcan su expresión, con fines terapéuticos

Effect of the β-amyloid peptide on microglia activation: ATP release

Previous studies have shown a key role of microglial cells in the neuroinflammatory processes associated with some neurodegenerative diseases, such as Alzheimer’s disease (AD). Microglia sense several types of diffusible molecules that regulate the multiple repertoire of microglial functions. Among them, extracellular nucleotides, acting on microglial P2 receptors, have central roles. In this sense, the ionotropic P2X7 receptor has gained recognition as a key regulator of microglial-mediated inflammatory responses.It is known that microglia releases ATP and other nucleotides to the extracellular medium. Although several mechanisms, such as release trough conexins or panexins, has been proposed, a vesicular origin for this released nucleotides, relying on the activity of the vesicular nucleotide transporter (VNUT), cannot be ruled out.In this work we evaluated whether the expression of VNUT and the P2X7 receptor, as well as the ATP release, could be modified in the reactive microglia. To achieve microglia activation we stimulated the cells with the lipopolysaccharide (LPS). Moreover, we analyzed the effect of the b-amyloid peptide b1-42, which is also able to activate the microglial cells, on the expression of VNUT and the ATP release in the microglia.Previous studies have shown a key role of microglial cells in the neuroinflammatory processes associated with some neurodegenerative diseases, such as Alzheimer’s disease (AD). Microglia sense several types of diffusible molecules that regulate the multiple repertoire of microglial functions. Among them, extracellular nucleotides, acting on microglial P2 receptors, have central roles. In this sense, the ionotropic P2X7 receptor has gained recognition as a key regulator of microglial-mediated inflammatory responses.It is known that microglia releases ATP and other nucleotides to the extracellular medium. Although several mechanisms, such as release trough conexins or panexins, has been proposed, a vesicular origin for this released nucleotides, relying on the activity of the vesicular nucleotide transporter (VNUT), cannot be ruled out.In this work we evaluated whether the expression of VNUT and the P2X7 receptor, as well as the ATP release, could be modified in the reactive microglia. To achieve microglia activation we stimulated the cells with the lipopolysaccharide (LPS). Moreover, we analyzed the effect of the b-amyloid peptide b1-42, which is also able to activate the microglial cells, on the expression of VNUT and the ATP release in the microgli

Increased Ap4A levels and ecto-nucleotidase activity in glaucomatous mice retina

The pathogenesis of glaucoma involves numerous intracellular mechanisms including the purinergic system contribution. Furthermore, the presence and release of nucleotides and dinucleotides during the glaucomatous damage and the maintenance of degradation machinery through ecto-nucleotidase activity are participating in the modulation of the suitable extracellular complex balance. The aim of this study was to investigate the levels of diadenosine tetraphosphate (Ap4A) and the pattern of ecto-nucleotidase activity expression in glaucomatous retinas during the progress the pathology. Ap4A levels were analyzed by HPLC in glaucomatous retinas from the DBA/2J mice at 3, 9, 15, and 23 months of age. For that, retinas were dissected as flattened whole-mounts and stimulated in Ringer buffer with or without 59 mM KCl. NPP1 expression was analyzed by RT-PCR and western blot and its distribution was assessed by immunohistochemistry studies examined under confocal microscopy. Glaucomatous mice exhibited Ap4A values, which changed in stimulated retinas as long as the pathology progressed varying from 0.73 ± 0.04 (3 months) to 0.170 ± 0.05 pmol/mg retina (23 months). Concomitantly, NPP1 expression was significantly increased (82.15%) in the DBA/2J mice at 15 months. Furthermore, immunohistochemical studies showed that NPP1 labeling was stronger in OPL and IPL labeling tangentially in the vitreal part of the retina and was upregulated at 15 months of age. Our findings demonstrate that Ap4A decreased levels may be related with exacerbated activity of NPP1 protein in glaucomatous degeneration and in this way contributing to elucidate different mechanisms involved in retinal impairment in glaucomatous degeneration

Papel fisiológico de los nucleótidos extracelulares en el sistema nervioso central: señalización vía receptores P2X y P2Y

In the last few years nucleotide receptors, the ionotropic P2X1-7 subunits and the metabotropic P2Y1, 2, 4, 6, 11, 12, 13, 14, have acquired an excepcional importance due to their strategic location in organs and tissues, their great variety along with the complexity of the associated signalling pathways and the first evidence of the serious alterations entailed in their dysfunctions. Our group has been pioneer in the characterization of these receptors in the nervous system, where we defined their location and functionality. The abundant presence, at a presynaptic level, of P2X3 and P2X7 should be emphasized, where by means of calcium intake they induce neurotransmitter exocytosis, such as glutamate, GABA, catecholamines and acetylcholine among others, as described in previous works by our group. In addition, they induce an extensive remodeling of the terminal’s cytoskeleton and exocytotic mechanisms through CaMKII and they can interact widely with other ionotropic and metabotropic receptors co-existing in nearby areas. Neural cells also exhibit the presence of most P2Y receptors signalling through a large variety of intracellular cascades. Recently we have demostrated that P2Y metabotropic receptors of the sub-family activated by ADP, especially P2Y13, are connected with the signalling towards GSK3 and â-catenin, opening new ways of understading the nucleotide function in survival and maintenance of neural cells. In addition both P2X and P2Y receptors play a role in early developmental stages and neural maturation where their function has to be fully understanded. Nucleotide receptors are also very abundant in glial cells, and our group has shown that most P2Y receptors are present and fully functional in cultured astrocytes, where, depending on the subtype receptor they activate a large variety of signalling cascades.En los ultimos anos los receptores de nucleotidos, receptores ionotropicos P2X1-7 y metabotropicos P2Y1, 2, 4, 6, 11, 12, 13, 14, han adquirido una importancia excepcional debido a su localizacion estrategica en organos y tejidos, a su gran variedad junto con la complejidad de vias de senalizacion a las que estan asociados y a las primeras evidencias de importantes alteraciones debidas a su mal funcionamiento. Nuestro grupo ha sido pionero en la caracterizacion estos receptores en el sistema nervioso, donde definimos su localizacion y su funcionalidad. La abundante presencia, a nivel presinaptico, de las subunidades P2X3 y P2X7 debe ser resaltada, donde gracias a la entrada de calcio inducen la exocitosis de varios neurotransmisores, como glutamato, GABA, catecolaminas y acetilcolina entre otros, como ha sido descrito por nuestro grupo en trabajos previos. Ademas, estos receptores inducen una profunda remodelacion del citoesqueleto de las terminales nerviosas y de los mecanismos exocitoticos a traves de la CaMKII y pueden interactuar con otros receptores ionotropicos y metabotropicos co-existentes en sus cercanias. La mayoria de los receptores P2Y tambien estan presentes en las celulas nerviosas, activando vias de senalizacion a traves de una gran variedad de cascadas intracelulares. Recientemente hemos demostrado que los receptores metabotropicos P2Y pertenecientes a la sub-familia de receptores activados por ADP, especialmente el P2Y13, estan conectados con la senalizacion hacia GSK3 y ƒÀ-catenina, lo que abre nuevas vias para la comprension de la funcion de los nucleotidos en la supervivencia y el mantenimiento de las celulas nerviosas. Ademas, tanto los receptores P2X como los P2Y juegan un papel en los estadios iniciales del desarrollo y en la maduracion neuronal donde su funcion aun ha de ser plenamente comprendida. Los receptores de nucleotidos son tambien muy abundantes en las celulas gliales, y nuestro grupo ha demostrado que la mayoría de los receptores P2Y están presentes y son plenamente funcionales en astrocitos en cultivo, donde, dependiendo del subtipo de receptor, activan una gran variedad de cascadas de señalización

Los receptores de nucleótidos P2Y reducen la entrada de calcio inducida por despolarización en terminales sinápticos de cerebro medio de rata

Studies were carried out to determine the presence and function of P2Y receptors in synaptic terminals from rat midbrain. Immunochemical essays have shown the expression of the nucleotide P2Y2 and P2Y4 receptors. Activation of these receptors induces a reduction of the calcium entrance into the terminals, when stimulated with depolarising agents. A similar effect is produced by agonists of metabotropic receptors, such as the adenosine A1 or GABAB receptors, which are well known for its role in the presynaptic control or transmitter release. Activation of the P2Y receptors also triggers a reduction in the intrasynaptosomal cAMP concentration. Thus, these receptors seem to be negatively coupled to adenylate cyclase activity. However, we postulate that P2Y receptors are able to reduce calcium entrance into the terminals by the activation of the corresponding G protein, dissociation of the trimer and action of the âã subunits on voltage activated calcium channels.Se han llevado a cabo estudios para determinar la presencia y funcion de receptores P2Y en terminales sinapticas de cerebro medio. Ensayos imnunoquimicos han mostrado la expresion, en dichas terminales, de los receptores P2Y2 y P2Y4. La activacion de estos receptores por sus agonistas selectivos lleva a una reduccion en la entrada de calcio en las terminales, inducida por agentes despolarizantes. Este efecto es similar al que producen agonistas de otros receptores metabotropicos, como los A1 de adenosina o los GABAB, conocidos por su papel en el control presinaptico de la liberacion de neurotransmisores. La activacion de los receptores P2Y conduce asimismo a una disminucion en los niveles intrasinaptosomales de AMPc, por lo que estos receptores parecen estar acoplados negativamente a la actividad de la adenilato ciclasa. Sin embargo, se plantea como hipotesis que los receptores P2Y pudiesen actuar reduciendo la entrada de calcio en las terminales a traves de la disociacion de la proteina G a la que estan acoplados, y la posterior accion del dimero ¿À¿Á sobre canales de calcio dependientes de voltaje