RESUMEN
Dopamine D2 receptor (D2R) is expressed in striatopallidal neurons and decreases forskolin-stimulated cyclic adenine monophosphate (cAMP) accumulation and gamma-aminobutyric acid (GABA) release. Dopamine D3 receptor (D3R) mRNA is expressed in a population of striatal D2R-expressing neurons. Also, D3R protein and binding have been reported in the neuropil of globus pallidus. We explore whether D2R and D3R colocalize in striatopallidal terminals and whether D3R modulates the D2R effect on forskolin-stimulated [3H]cAMP accumulation in pallidal synaptosomes and high K+ stimulated-[3H]GABA release in pallidal slices. Previous reports in heterologous systems indicate that calmodulin (CaM) and CaMKII modulate D2R and D3R functions; thus, we study whether this system regulates its functional interaction. D2R immunoprecipitates with CaM, and pretreatment with ophiobolin A or depolarization of synaptosomes with 15 mM of K+ decreases it. Both treatments increase the D2R inhibition of forskolin-stimulated [3H]cAMP accumulation when activated with quinpirole, indicating a negative modulation of CaM on D2R function. Quinpirole also activates D3R, potentiating D2R inhibition of cAMP accumulation in the ophiobolin A-treated synaptosomes. D2R and D3R immunoprecipitate in pallidal synaptosomes and decrease after the kainic acid striatal lesion, indicating the striatal origin of the presynaptic receptors. CaM-kinase II alfa (CaMKIIα) immunoprecipitates with D3R and increases after high K+ depolarization. In the presence of KN62, a CaMKIIα blocker, D3R potentiates D2R effects on cAMP accumulation in depolarized synaptosomes and GABA release in pallidal slices, indicating D3R function regulation by CaMKIIα. Our data indicate that D3R potentiates the D2R effect on cAMP accumulation and GABA release at pallidal terminals, an interaction regulated by the CaM-CaMKIIα system.
Asunto(s)
Calmodulina , Receptores de Dopamina D3 , Sesterterpenos , Receptores de Dopamina D3/metabolismo , Quinpirol/farmacología , Calmodulina/metabolismo , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/metabolismo , Colforsina , Receptores de Dopamina D2/metabolismo , Ácido gamma-Aminobutírico/metabolismoRESUMEN
Two major groups of terminals release GABA within the Globus pallidus; one group is constituted by projections from striatal neurons, while endings of the intranuclear collaterals form the other one. Each neurons' population expresses different subtypes of dopamine D2-like receptors: D2 R subtype is expressed by encephalin-positive MSNs, while pallidal neurons express the D4 R subtype. The D2 R modulates the firing rate of striatal neurons and GABA release at their projection areas, while the D4 R regulates Globus pallidus neurons excitability and GABA release at their projection areas. However, it is unknown if these receptors control GABA release at pallido-pallidal collaterals and regulate motor behavior. Here, we present neurochemical evidence of protein content and binding of D4 R in pallidal synaptosomes, control of [3 H] GABA release in pallidal slices of rat, electrophysiological evidence of the presence of D4 R on pallidal recurrent collaterals in mouse slices, and turning behavior induced by D4 R antagonist microinjected in amphetamine challenged rats. As in projection areas of pallidal neurons, GABAergic transmission in pallido-pallidal recurrent synapses is under modulation of D4 R, while the D2 R subtype, as known, modulates striato-pallidal projections. Also, as in projection areas, D4 R contributes to control the motor activity differently than D2 R. This study could help to understand the organization of intra-pallidal circuitry.
Asunto(s)
Globo Pálido , Receptores de Dopamina D4 , Animales , Cuerpo Estriado/metabolismo , Dopamina , Globo Pálido/metabolismo , Ratones , Ratas , Receptores de Dopamina D1/metabolismoRESUMEN
Because activation of D2 receptors reverses the neurochemical effects of cannabinoids, we examined whether increasing dopaminergic tone in the globus pallidus (GPe) switches cannabinoid induced depression of synaptic transmission. GABAergic synaptic currents evoked in pallidal neurons by stimulation of striatal projections (IPSCs) were depressed by perfusion with the CB1R agonist ACEA. Coactivation of D2Rs with quinpirole converted the depression into stimulation. Pretreatment with pertussis toxin (PTX) to limit Gi/o protein coupling also switched the CB1R-induced depression of IPSCs. The stimulation of IPSCs was blocked by the selective PKA blocker H89. Changes in the paired pulse ratio during both inhibitory and stimulatory responses indicate that the effects are due to changes in transmitter release. Postsynaptic depolarization induces endocannabinoid release that inhibits transmitter release (DSI). When D2Rs were activated with quinpirole, depolarization increased transmission instead of depressing it. This increase was blocked by AM251. We also examined the effects of CB1R/D2R coactivation on cAMP accumulation in the GPe to further verify that the AC/PKA cascade is involved. CB1R/D2R coactivation converted the inhibition of cAMP seen when each receptor is stimulated alone into a stimulation. We also determined the effects on turning behavior of unilateral injection of ACEA into the GPe of awake animals and its modification by dopamine antagonists. Blockade of D2 family receptors with sulpiride antagonized the motor effects of ACEA. We show, for the first time, that cannabinoid-inhibition of synaptic transmission in the GPe becomes a stimulation after D2Rs or PTX treatment and that the switch is probably relevant for the control of motor behavior.
Asunto(s)
Dopamina/metabolismo , Endocannabinoides/metabolismo , Globo Pálido/metabolismo , Receptor Cannabinoide CB1/metabolismo , Transmisión Sináptica/fisiología , Ácido gamma-Aminobutírico/metabolismo , Animales , Moduladores de Receptores de Cannabinoides/farmacología , AMP Cíclico/metabolismo , Globo Pálido/efectos de los fármacos , Masculino , Ratones , Actividad Motora/efectos de los fármacos , Actividad Motora/fisiología , Neuronas/efectos de los fármacos , Neuronas/fisiología , Ratas Wistar , Receptor Cannabinoide CB1/agonistas , Receptor Cannabinoide CB1/antagonistas & inhibidores , Receptores de Dopamina D2/metabolismo , Transmisión Sináptica/efectos de los fármacos , Técnicas de Cultivo de TejidosRESUMEN
The monocyte-macrophage lineage shows a high degree of diversity and plasticity. Once they infiltrate tissues, they may acquire two main functional phenotypes, being known as the classically activated type 1 macrophages (M1) and the alternative activated type 2 macrophages (M2). The M1 phenotype can be induced by bacterial products and interferon-γ and exerts a cytotoxic effect on cancer cells. Conversely, the alternatively activated M2 phenotype is induced by Il-4/IL13 and promotes tumor cell growth and vascularization. Although receptor for advanced glycation end-products (RAGE) engagement in M1 macrophages has been reported by several groups to promote inflammation, nothing is known about the functionality of RAGE in M2 macrophages. In the current study, we demonstrate that RAGE is equally expressed in both macrophage phenotypes and that RAGE activation by high-mobility group protein box1 (HMGB1) promotes protumoral activities of M2 macrophages. MKN45 cells co-cultured with M2 macrophages treated with HMGB1 at different times displayed higher invasive abilities. Additionally, conditioned medium from HMGB1-treated M2 macrophages promotes angiogenesis in vitro. RAGE-targeting knockdown abrogates these activities. Overall, the present findings suggest that HMGB1 may contribute, by a RAGE-dependent mechanism, to the protumoral activities of the M2 phenotype.
Asunto(s)
Proteína HMGB1/farmacología , Macrófagos/efectos de los fármacos , Receptor para Productos Finales de Glicación Avanzada/genética , Microambiente Tumoral/genética , Western Blotting , Línea Celular , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Proliferación Celular/genética , Técnicas de Cocultivo , Expresión Génica/efectos de los fármacos , Humanos , Interleucina-10/genética , Interleucina-10/metabolismo , Interleucina-1beta/genética , Interleucina-1beta/metabolismo , Activación de Macrófagos/efectos de los fármacos , Activación de Macrófagos/genética , Macrófagos/clasificación , Macrófagos/metabolismo , Neoplasias/genética , Neoplasias/metabolismo , Neoplasias/patología , Óxido Nítrico Sintasa de Tipo II/genética , Óxido Nítrico Sintasa de Tipo II/metabolismo , Interferencia de ARN , Receptor para Productos Finales de Glicación Avanzada/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Factor de Crecimiento Transformador beta/genética , Factor de Crecimiento Transformador beta/metabolismo , Factor de Necrosis Tumoral alfa/genética , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
Estradiol (E2) accelerates egg transport by a nongenomic action, requiring activation of estrogen receptor (ER) and successive cAMP and IP3 production in the rat oviduct. Furthermore, E2 increases IP3 production in primary cultures of oviductal smooth muscle cells. As smooth muscle cells are the mechanical effectors for the accelerated oocyte transport induced by E2 in the oviduct, herein we determined the mechanism by which E2 increases IP3 in these cells. Inhibition of protein synthesis by Actinomycin D did not affect the E2-induced IP3 increase, although this was blocked by the ER antagonist ICI182780 and the inhibitor of phospholipase C (PLC) ET-18-OCH3. Immunoelectron microscopy for ESR1 or ESR2 showed that these receptors were associated with the plasma membrane, indicating compatible localization with E2 nongenomic actions in the smooth muscle cells. Furthermore, ESR1 but not ESR2 agonist mimicked the effect of E2 on the IP3 level. Finally, E2 stimulated the activity of a protein associated with the contractile tone, calcium/calmodulin-dependent protein kinase II (CaMKII), in the smooth muscle cells. We conclude that E2 increases IP3 by a nongenomic action operated by ESR1 and that involves the activation of PLC in the smooth muscle cells of the rat oviduct. This E2 effect is associated with CaMKII activation in the smooth muscle cells, suggesting that IP3 and CaMKII are involved in the contractile activity necessary to accelerate oviductal egg transport.
Asunto(s)
Estradiol/farmacología , Inositol 1,4,5-Trifosfato/biosíntesis , Miocitos del Músculo Liso/metabolismo , Oviductos/metabolismo , Animales , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/antagonistas & inhibidores , Membrana Celular/efectos de los fármacos , Membrana Celular/metabolismo , Antagonistas de Estrógenos/farmacología , Receptor alfa de Estrógeno/agonistas , Receptor alfa de Estrógeno/antagonistas & inhibidores , Receptor beta de Estrógeno/agonistas , Receptor beta de Estrógeno/antagonistas & inhibidores , Femenino , Técnicas In Vitro , Ratones , Contracción Muscular/efectos de los fármacos , Miocitos del Músculo Liso/efectos de los fármacos , Oviductos/efectos de los fármacos , Ratas Sprague-Dawley , Fosfolipasas de Tipo C/antagonistas & inhibidoresRESUMEN
In the rat oviduct, estradiol (E2) accelerates egg transport by a nongenomic action that requires previous conversion of E2 to methoxyestrogens via catechol-O-methyltranferase (COMT) and activation of estrogen receptor (ER) with subsequent production of cAMP and inositol triphosphate (IP3). However, the role of the different oviductal cellular phenotypes on this E2 nongenomic pathway remains undetermined. The aim of this study was to investigate the effect of E2 on the levels of cAMP and IP3 in primary cultures of secretory and smooth muscle cells from rat oviducts and determine the mechanism by which E2 increases cAMP in the secretory cells. In the secretory cells, E2 increased cAMP but not IP3, while in the smooth muscle cells E2 decreased cAMP and increased IP3. Suppression of protein synthesis by actinomycin D did not prevent the E2-induced cAMP increase, but this was blocked by the ER antagonist ICI 182â780 and the inhibitors of COMT OR 486, G protein-α inhibitory (Gαi) protein pertussis toxin and adenylyl cyclase (AC) SQ 22536. Expression of the mRNA for the enzymes that metabolizes estrogens, Comt, Cyp1a1, and Cyp1b1 was found in the secretory cells, but this was not affected by E2. Finally, confocal immunofluorescence analysis showed that E2 induced colocalization between ESR1 (ERα) and Gαi in extranuclear regions of the secretory cells. We conclude that E2 differentially regulates cAMP and IP3 in the secretory and smooth muscle cells of the rat oviduct. In the secretory cells, E2 increases cAMP via a nongenomic action that requires activation of COMT and ER, coupling between ESR1 and Gαi, and stimulation of AC.
Asunto(s)
AMP Cíclico/metabolismo , Estradiol/farmacología , Oviductos/efectos de los fármacos , Receptores de Estrógenos/metabolismo , Transducción de Señal/efectos de los fármacos , Animales , Catecol O-Metiltransferasa/metabolismo , Dactinomicina/farmacología , Estradiol/análogos & derivados , Antagonistas del Receptor de Estrógeno/farmacología , Femenino , Fulvestrant , Miocitos del Músculo Liso/efectos de los fármacos , Miocitos del Músculo Liso/metabolismo , Oviductos/metabolismo , Ratas , Transducción de Señal/fisiologíaRESUMEN
Cells from innate immune system are activated by the engagement of germ-line encoded pattern-recognition receptors (PRRs) in response to the microbial insult. These receptors are able to recognize either the presence of highly conserved microbial components called pathogen-associated molecular patterns or endogenous danger-associated molecular patterns. These danger signals are recognized by different types of (PRRs), including the receptor for advanced glycation end products. This new PRR share both ligands and intracellular signaling with Toll-like receptors and thus may cooperate with each other as essential partners to strength inflammatory response. This review summarizes recent advances in understanding the promiscuity of this receptor as well as its role in the context of innate immunity by triggering an inflammatory response when innate immune cells detect infection or tissue injury.
Asunto(s)
Inmunidad Innata/fisiología , Receptores Inmunológicos/metabolismo , Animales , Humanos , Ligandos , Receptor para Productos Finales de Glicación Avanzada , Receptores de Reconocimiento de Patrones/metabolismo , Transducción de SeñalRESUMEN
Firstly described in 1992, the receptor for advanced glycation end-products has attracted increasing attention due to its diverse ligand repertoire and involvement in several pathophysiological processes associated with inflammation such as in diabetes, cancer, autoimmune diseases and neurodegenerative diseases. This receptor in addition to its binding capacity for advanced glycation end-products also recognizes some molecules classified as both, pathogen- and damage-associated molecular patterns and thus triggering the transcription of genes encoding inflammatory mediators. Some of these ligands are common for both, the receptor of advanced glycation end-products and members of the Toll-like receptor family, generating shared signaling cascades. Furthermore, these receptors may cooperate as essential partners through the recruitment and assembly of homo- and hetero-oligomers in order to strengthen the inflammatory response. The purpose of this review is to highlight the importance of some particular features of this multiligand receptor, its signaling cascade as well as the cross-talk with some members of the Toll-like receptor family.