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Involved in immunity and reproduction, natural killer (NK) cells offer opportunities to develop new immunotherapies to treat infections and cancer or to alleviate pregnancy complications. Most current strategies use cytokines or antibodies to enhance NK-cell function, but none use ion channel modulators, which are widely used in clinical practice to treat hypertension, diabetes, epilepsy, and other conditions. Little is known about ion channels in NK cells. We show that Kcnj8, which codes for the Kir6.1 subunit of a certain type of ATP-sensitive potassium (K ATP ) channel, is highly expressed in murine splenic and uterine NK cells compared to other K + channels previously identified in NK cells. Kcnj8 expression is highest in the most mature subset of splenic NK cells (CD27 - CD11b + ) and in NKG2A + or Ly49C/I + educated uterine NK cells. Using patch clamping, we show that a subset of NK cells expresses a current sensitive to the Kir6.1 blocker PNU-37883A. Kcnj8 does not participate in NK cell degranulation in response to tumor cells in vitro or rejection of tumor cells in vivo . Transcriptomics show that genes previously implicated in NK cell development are amongst those differentially expressed in CD27 - CD11b + NK cells deficient of Kcnj8 . Indeed, we found that mice with NK-cell specific Kcnj8 gene ablation have fewer CD11b + CD27 - and KLRG-1 + NK cells in the bone barrow and spleen. These results show that the K ATP subunit Kir6.1 has a key role in NK-cell development.
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Cigarette smoke has been recognized as a major risk factor for cardiovascular disease. However, its direct effects on rodent and human cardiomyocytes and its cellular mechanisms are not fully understood. In this study, we examined the direct effects of cigarette smoke extract (CSE) on contractile functions, intracellular Ca2+ dynamics, and mitochondrial function using cultured or freshly isolated rat ventricular myocytes and human induced pluripotent stem cell (iPS)-derived cardiomyocytes. In rat cardiomyocytes, CSE (≥0.1%) resulted in a time- and concentration-dependent cessation of spontaneous beating of cultured cardiomyocytes, eventually leading to cell death, which indicates direct toxicity. In addition, 1% CSE reduced contractile function of freshly isolated ventricular myocytes. Similar contractile dysfunction (declined spontaneous beating rate and contractility) was also observed in human iPS-derived cardiomyocytes. Regarding intracellular Ca2+ dynamics, 1% CSE increased the Ca2+ transient amplitude by greatly increasing systolic Ca2+ levels and slightly increasing diastolic Ca2+ levels. CSE also accelerated the decay of Ca2+ transients, and triggered spike-shaped Ca2+ transients in some cells. These results indicate that CSE causes abnormal Ca2+ dynamics in cardiomyocytes. Furthermore, CSE induced a cascade of mitochondrial dysfunctions, including increased mitochondrial reactive oxygen species, opening of mitochondrial permeability transition pore, reduction of mitochondrial membrane potential, and release of cytochrome c from mitochondria. These results suggest that CSE-induced contractile dysfunction and myocardial cell death is caused by abnormal Ca2+ dynamics and subsequent mitochondrial dysregulation, which would result in reduced bioenergetics and activation of cell death pathways.
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Fumar Cigarrillos , Células Madre Pluripotentes Inducidas , Enfermedades Mitocondriales , Humanos , Ratas , Animales , Ratas Sprague-Dawley , Miocitos Cardíacos/metabolismo , Células Madre Pluripotentes Inducidas/metabolismo , Calcio/metabolismo , Enfermedades Mitocondriales/metabolismo , Productos de TabacoRESUMEN
BACKGROUND AND PURPOSE: Licorice (liquorice) is a common food additive and is used in Chinese medicine. Excess licorice intake can induce atrial fibrillation. Patients with atrial fibrillation possess constitutively activated G protein-gated inwardly rectifying K+ (GIRK) channels. Whether licorice affects GIRK channel activity is unknown. We aimed to clarify the effects of licorice ingredients on GIRK current and the mechanism of action. EXPERIMENTAL APPROACH: A major component of licorice, glycyrrhizic acid (GA), and its metabolite, 18ß-glycyrrhetinic acid (18ß-GA), were tested. We performed electrophysiological recordings in Xenopus oocytes to examine the effects of GA and 18ß-GA on various GIRK subunits (Kir 3.1-Kir 3.4), mutagenesis analyses to identify the crucial residues for drug action and motion analysis in cultured rat atrial myocytes to clarify effects of 18ß-GA on atrial functions. KEY RESULTS: GA inhibited Kir 3.1-containing channels, while 18ß-GA activated all Kir 3.x subunits. A pore helix residue Phe137 in Kir 3.1 was critical for GA-mediated inhibition, and the corresponding Ser148 in Kir 3.2 was critical for 18ß-GA-mediated activation. 18ß-GA activated GIRK channel in a Gßγ -independent manner, whereas phosphatidylinositol 4,5-bisphosphate (PIP2 ) was essential for activation. Glu236 located at the cytoplasmic pore of Kir 3.2 appeared to be important to interactions with 18ß-GA. In rat atrial myocytes, 18ß-GA suppressed spontaneous beating via activation of GIRK channels. CONCLUSION AND IMPLICATIONS: GA acts as a novel GIRK inhibitor, and 18ß-GA acts as a novel GIRK activator. 18ß-GA alters atrial function via activation of GIRK channels. This study elucidates the pharmacological activity of licorice ingredients and provides information for drug design.
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Fibrilación Atrial , Ácido Glicirretínico/análogos & derivados , Glycyrrhiza , Humanos , Ratas , Animales , Canales de Potasio Rectificados Internamente Asociados a la Proteína G/metabolismo , Proteínas de Unión al GTP/metabolismoRESUMEN
Background: KATP channels have diverse roles, including regulation of insulin secretion and blood flow, and protection against biological stress responses and are excellent therapeutic targets. Different subclasses of KATP channels exist in various tissue types due to the unique assemblies of specific pore-forming (Kir6.x) and accessory (SURx) subunits. The majority of pharmacological openers and blockers act by binding to SURx and are poorly selective against the various KATP channel subclasses. Methods and Results: We used 3D models of the Kir6.2/SUR homotetramers based on existing cryo-EM structures of channels in both the open and closed states to identify a potential agonist binding pocket in a functionally critical area of the channel. Computational docking screens of this pocket with the Chembridge Core chemical library of 492,000 drug-like compounds yielded 15 top-ranked "hits", which were tested for activity against KATP channels using patch clamping and thallium (Tl+) flux assays with a Kir6.2/SUR2A HEK-293 stable cell line. Several of the compounds increased Tl+ fluxes. One of them (CL-705G) opened Kir6.2/SUR2A channels with a similar potency as pinacidil (EC50 of 9 µM and 11 µM, respectively). Remarkably, compound CL-705G had no or minimal effects on other Kir channels, including Kir6.1/SUR2B, Kir2.1, or Kir3.1/Kir3.4 channels, or Na+ currents of TE671 medulloblastoma cells. CL-705G activated Kir6.2Δ36 in the presence of SUR2A, but not when expressed by itself. CL-705G activated Kir6.2/SUR2A channels even after PIP2 depletion. The compound has cardioprotective effects in a cellular model of pharmacological preconditioning. It also partially rescued activity of the gating-defective Kir6.2-R301C mutant that is associated with congenital hyperinsulinism. Conclusion: CL-705G is a new Kir6.2 opener with little cross-reactivity with other channels tested, including the structurally similar Kir6.1. This, to our knowledge, is the first Kir-specific channel opener.
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During de novo plant organ regeneration, auxin induction mediates the formation of a pluripotent cell mass called callus, which regenerates shoots upon cytokinin induction. However, molecular mechanisms underlying transdifferentiation remain unknown. Here, we showed that the loss of HDA19, a histone deacetylase (HDAC) family gene, suppresses shoot regeneration. Treatment with an HDAC inhibitor revealed that the activity of this gene is essential for shoot regeneration. Further, we identified target genes whose expression was regulated through HDA19-mediated histone deacetylation during shoot induction and found that ENHANCER OF SHOOT REGENERATION 1 and CUP-SHAPED COTYLEDON 2 play important roles in shoot apical meristem formation. Histones at the loci of these genes were hyperacetylated and markedly upregulated in hda19. Transient ESR1 or CUC2 overexpression impaired shoot regeneration, as observed in hda19. Therefore, HDA19 mediates direct histone deacetylation of CUC2 and ESR1 loci to prevent their overexpression at the early stages of shoot regeneration.
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Several lines of evidence have clarified that the key transmission pathways of itching sensation travel from the periphery to the central nervous system (CNS). Despite the functional significance of gastrin-releasing peptide (GRP) and its cognate receptor in the itch processing mechanism in the spinal dorsal horn (SDH), the roles of GRP-expressing (GRP+ ) neurons in different regions remain unclear. This study aimed to determine whether GRP+ neurons in the CNS directly modulated itch processing. To specifically activate spinal and supraspinal GRP neurons by the designer receptors exclusively activated by designer drugs (DREADDs) system, CAG-LSL-Gq-DREADD mice were crossed with GRP-Cre mice, resulting in the development of GRP-hM3Dq mice. Immunohistochemistry showed that hM3Dq was highly expressed in the SDH and brainstem closely related to sensory processing. The intraperitoneal, intrathecal, or intracerebroventricular administration of clozapine-N-oxide, an agonist of hM3Dq, strongly elicited dermatome-dependent itch-related scratching behavior, but did not change pain sensitivity. Importantly, GRP-Gq-DREADD-mediated scratching behavior in GRP-hM3Dq mice was not affected by the ablation of transient receptor potential vanilloid 1+ sensory C-fibers, and it was also observed to a similar degree under chronic itch conditions. Furthermore, there were no significant sex differences in the scratching behavior elicited by GRP-Gq-DREADD, suggesting that itch-dominant roles of central GRP+ neurons might be common in both sexes, at least under normal physiological conditions. These novel findings not only contribute to understanding the functional roles of central GRP+ neurons further, but also propose the development of future effective therapeutics for intractable itching.
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Péptido Liberador de Gastrina/fisiología , Neuronas/fisiología , Prurito/fisiopatología , Animales , Conducta Animal , Clozapina/análogos & derivados , Clozapina/farmacología , Ciclopropanos , Dermatitis por Contacto , Femenino , Haptenos , Masculino , Ratones Endogámicos C57BL , Ratones TransgénicosRESUMEN
Despite growing evidence suggesting that spinal microglia play an important role in the molecular mechanism underlying experimental neuropathic pain (NP) in male rodents, evidence regarding the sex-dependent role of these microglia in NP is insufficient. In this study, we evaluated the effects of microglial regulation on NP using Gi-designer receptors exclusively activated by designer drugs (Gi-DREADD) driven by the microglia-specific Cx3cr1 promoter. For the Cre-dependent expression of human Gi-coupled M4 muscarinic receptors (hM4Di) in CX3C chemokine receptor 1-expressing (CX3CR1+) cells, R26-LSL-hM4Di-DREADD mice were crossed with CX3CR1-Cre mice. Mouse models of NP were generated by partial sciatic nerve ligation (PSL) and treatment with anti-cancer agent paclitaxel (PTX) or oxaliplatin (OXA), and mechanical allodynia was evaluated using the von Frey test. Immunohistochemistry revealed that hM4Di was specifically expressed on Iba1+ microglia, but not on astrocytes or neurons in the spinal dorsal horn of CX3CR1-hM4Di mice. PSL-induced mechanical allodynia was significantly attenuated by systemic (intraperitoneal, i.p.) administration of 10 mg/kg of clozapine N-oxide (CNO), a hM4Di-selective ligand, in male CX3CR1-hM4Di mice. The mechanical threshold in naive CX3CR1-hM4Di mice was not altered by i.p. administration of CNO. Consistently, local (intrathecal, i.t.) administration of CNO (20 nmol) significantly relieved PSL-induced mechanical allodynia in male CX3CR1-hM4Di mice. However, neither i.p. nor i.t. administration of CNO affected PSL-induced mechanical allodynia in female CX3CR1-hM4Di mice. Both i.p. and i.t. administration of CNO relieved PTX-induced mechanical allodynia in male CX3CR1-hM4Di mice, and a limited effect of i.p. CNO was observed in female CX3CR1-hM4Di mice. Unlike PTX-induced allodynia, OXA-induced mechanical allodynia was slightly improved, but not significantly relieved, by i.p. administration of CNO in both male and female CX3CR1-hM4Di mice. These results suggest that spinal microglia can be regulated by Gi-DREADD and support the notion that CX3CR1+ spinal microglia play sex-dependent roles in nerve injury-induced NP; however, their roles may vary among different models of NP.
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Protein silencing represents an essential tool in biomedical research. Targeted protein degradation (TPD) strategies exemplified by PROTACs are rapidly emerging as modalities in drug discovery. However, the scope of current TPD techniques is limited because many intracellular materials are not substrates of proteasomal clearance. Here, we described a novel targeted-clearance strategy (autophagy-targeting chimera [AUTAC]) that contains a degradation tag (guanine derivatives) and a warhead to provide target specificity. As expected from the substrate scope of autophagy, AUTAC degraded fragmented mitochondria as well as proteins. Mitochondria-targeted AUTAC accelerated both the removal of dysfunctional fragmented mitochondria and the biogenesis of functionally normal mitochondria in patient-derived fibroblast cells. Cytoprotective effects against acute mitochondrial injuries were also seen. Canonical autophagy is viewed as a nonselective bulk decomposition system, and none of the available autophagy-inducing agents exhibit useful cargo selectivity. With its target specificity, AUTAC provides a new modality for research on autophagy-based drugs.
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Autofagia/fisiología , Guanina/química , Proteolisis/efectos de los fármacos , Proteínas Relacionadas con la Autofagia/metabolismo , Línea Celular , Guanina/fisiología , Humanos , Mitocondrias/metabolismo , Mitofagia/fisiología , Ingeniería de Proteínas/métodos , Proteínas Quinasas/metabolismo , Estabilidad ProteicaRESUMEN
The EF-hand calcium (Ca2+)-binding protein, neuronal Ca2+ sensor-1 (NCS-1/frequenin), is predominantly expressed in neuronal tissues and plays a crucial role in neuronal functions, including synaptic transmission and plasticity. NCS-1 has diverse functional roles, as elucidated in the past 15 years, which include the regulation of phosphatidylinositol 4-kinase IIIß (PI-4K-ß) and several ion channels such as voltage-gated K+ and Ca2+ channels, the D2 dopamine receptors, and inositol 1,4,5-trisphosphate receptors (InsP3Rs). Functional analyses demonstrated that NCS-1 enhances exocytosis and neuronal survival after injury, as well as promotes learning and memory in mice. NCS-1 is also expressed in the heart including the Purkinje fibers (PFs) of the conduction system. NCS-1 interacts with KV4 K+ channels together with dipeptidyl peptidase-like protein-6 (DPP-6), and this macromolecule then composes the transient outward current in PFs and contributes to the repolarization of PF action potential, thus being responsible for idiopathic arrhythmia. Moreover, NCS-1 expression was reported to be significantly high at the immature stage and at hypertrophy in adults. That report demonstrated that NCS-1 positively regulates cardiac contraction in immature hearts by increasing intracellular Ca2+ signals through interaction with InsP3Rs. With the related signals, NCS-1 activates nuclear Ca2+ signals, which would be a mechanism underlying hormone-induced cardiac hypertrophy. Furthermore, NCS-1 contributes to stress tolerance in cardiomyocytes by activating mitochondrial detoxification pathways, with a key role in Ca2+-dependent pathways. In this review, we will discuss recent findings supporting the functional significance of NCS-1 in the brain and heart and will address possible underlying molecular mechanisms.
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Histone acetylation is an essential process in the epigenetic regulation of diverse biological processes, including environmental stress responses in plants. Previously, our research group identified a histone deacetylase (HDAC) inhibitor (HDI) that confers salt tolerance in Arabidopsis (Arabidopsis thaliana). In this study, we demonstrate that class I HDAC (HDA19) and class II HDACs (HDA5/14/15/18) control responses to salt stress through different pathways. The screening of 12 different selective HDIs indicated that seven newly reported HDIs enhance salt tolerance. Genetic analysis, based on a pharmacological study, identified which HDACs function in salinity stress tolerance. In the wild-type Columbia-0 background, hda19 plants exhibit tolerance to high-salinity stress, while hda5/14/15/18 plants exhibit hypersensitivity to salt stress. Transcriptome analysis revealed that the effect of HDA19 deficiency on the response to salinity stress is distinct from that of HDA5/14/15/18 deficiencies. In hda19 plants, the expression levels of stress tolerance-related genes, late embryogenesis abundant proteins that prevent protein aggregation and positive regulators such as ABI5 and NAC019 in abscisic acid signaling, were induced strongly relative to the wild type. Neither of these elements was up-regulated in the hda5/14/15/18 plants. The mutagenesis of HDA19 by genome editing in the hda5/14/15/18 plants enhanced salt tolerance, suggesting that suppression of HDA19 masks the phenotype caused by the suppression of class II HDACs in the salinity stress response. Collectively, our results demonstrate that HDIs that inhibit class I HDACs allow the rescue of plants from salinity stress regardless of their selectivity, and they provide insight into the hierarchal regulation of environmental stress responses through HDAC isoforms.
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Arabidopsis/efectos de los fármacos , Arabidopsis/fisiología , Histona Desacetilasas/metabolismo , Proteínas de Plantas/metabolismo , Salinidad , Sistemas CRISPR-Cas , Regulación Enzimológica de la Expresión Génica/fisiología , Regulación de la Expresión Génica de las Plantas/fisiología , Histona Desacetilasas/genética , Mutación , Análisis de Secuencia por Matrices de Oligonucleótidos , Proteínas de Plantas/genética , Cloruro de Sodio/toxicidad , Estrés FisiológicoRESUMEN
Intracellular Ca2+ signaling regulates diverse functions of the nervous system. Many of these neuronal functions, including learning and memory, are regulated by neuronal calcium sensor-1 (NCS-1). However, the pathways by which NCS-1 regulates these functions remain poorly understood. Consistent with the findings of previous reports, we revealed that NCS-1 deficient (Ncs1-/-) mice exhibit impaired spatial learning and memory function in the Morris water maze test, although there was little change in their exercise activity, as determined via treadmill-analysis. Expression of brain-derived neurotrophic factor (BDNF; a key regulator of memory function) and dopamine was significantly reduced in the Ncs1-/- mouse brain, without changes in the levels of glial cell-line derived neurotrophic factor or nerve growth factor. Although there were no gross structural abnormalities in the hippocampi of Ncs1-/- mice, electron microscopy analysis revealed that the density of large dense core vesicles in CA1 presynaptic neurons, which release BDNF and dopamine, was decreased. Phosphorylation of Ca2+/calmodulin-dependent protein kinase II-α (CaMKII-α, which is known to trigger long-term potentiation and increase BDNF levels, was significantly reduced in the Ncs1-/- mouse brain. Furthermore, high voltage electric potential stimulation, which increases the levels of BDNF and promotes spatial learning, significantly increased the levels of NCS-1 concomitant with phosphorylated CaMKII-α in the hippocampus; suggesting a close relationship between NCS-1 and CaMKII-α. Our findings indicate that NCS-1 may regulate spatial learning and memory function at least in part through activation of CaMKII-α signaling, which may directly or indirectly increase BDNF production.
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Proteínas Sensoras del Calcio Neuronal/metabolismo , Neuronas/metabolismo , Neuropéptidos/metabolismo , Transducción de Señal/fisiología , Aprendizaje Espacial/fisiología , Memoria Espacial/fisiología , Animales , Factor Neurotrófico Derivado del Encéfalo/metabolismo , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/metabolismo , Dopamina/metabolismo , Estimulación Eléctrica , Factor Neurotrófico Derivado de la Línea Celular Glial/metabolismo , Hipocampo/metabolismo , Ratones , Ratones Noqueados , Actividad Motora/fisiología , Proteínas Sensoras del Calcio Neuronal/genética , Neuropéptidos/genéticaRESUMEN
The stomatitis caused by anticancer agents and radiation therapy deteriorates patient QOL, potentially causing eating disorders as a result of pain. Although gargling and ointments can be used in the treatment of stomatitis, patients must spit out mouthwash after use, while ointment application requires a finger to be inserted into the oral cavity. In contrast, sprays eliminate these potential compliance problems. Therefore, we developed a stomatitis spray that remains on the oral mucosa. It has been reported that irsogladine maleate (IM) is effective against stomatitis via oral administration. IM is water insoluble; thus, it was dissolved with various cyclodextrins (CDs). Furthermore, we examined combination with gum ghatti (GG), a mucoadhesive polymer. The interaction between mucin and GG was examined by Quartz Crystal Microbalance with Dissipation monitoring. We found that GG exhibited mucoadhesion. Furthermore, we examined the healing effects of IM on stomatitis in a stomatitis model hamster. We found that stomatitis healed after direct application of IM. However, the model used in this experiment is not based on stomatitis caused by anticancer agents. Further study is therefore necessary.
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Vaporizadores Orales , Estomatitis/tratamiento farmacológico , Triazinas/administración & dosificación , Triazinas/uso terapéutico , Animales , Antineoplásicos/administración & dosificación , Antineoplásicos/efectos adversos , Antineoplásicos/uso terapéutico , Modelos Animales de Enfermedad , Masculino , Mesocricetus , Estomatitis/inducido químicamenteRESUMEN
Identification of the molecules involved in cell death/survival pathways is important for understanding the mechanisms of cell loss in cardiac disease, and thus is clinically relevant. Ca2+-dependent signals are often involved in these pathways. Here, we found that neuronal Ca2+-sensor-1 (NCS-1), a Ca2+-binding protein, has an important role in cardiac survival during stress. Cardiomyocytes derived from NCS-1-deficient (Ncs1-/-) mice were more susceptible to oxidative and metabolic stress than wild-type (WT) myocytes. Cellular ATP levels and mitochondrial respiration rates, as well as the levels of mitochondrial marker proteins, were lower in Ncs1-/- myocytes. Although oxidative stress elevated mitochondrial proton leak, which exerts a protective effect by inhibiting the production of reactive oxygen species in WT myocytes, this response was considerably diminished in Ncs1-/- cardiomyocytes, and this would be a major reason for cell death. Consistently, H2O2-induced loss of mitochondrial membrane potential, a critical early event in cell death, was accelerated in Ncs1-/- myocytes. Furthermore, NCS-1 was upregulated in hearts subjected to ischemia-reperfusion, and ischemia-reperfusion injury was more severe in Ncs1-/- hearts. Activation of stress-induced Ca2+-dependent survival pathways, such as Akt and PGC-1α (which promotes mitochondrial biogenesis and function), was diminished in Ncs1-/- hearts. Overall, these data demonstrate that NCS-1 contributes to stress tolerance in cardiomyocytes at least in part by activating certain Ca2+-dependent survival pathways that promote mitochondrial biosynthesis/function and detoxification pathways.
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Adaptación Biológica/genética , Inactivación Metabólica , Mitocondrias Cardíacas/metabolismo , Miocitos Cardíacos/metabolismo , Proteínas Sensoras del Calcio Neuronal/genética , Neuropéptidos/genética , Estrés Fisiológico , Adenosina Trifosfato/metabolismo , Animales , Respiración de la Célula , Supervivencia Celular , Células Cultivadas , Técnicas de Inactivación de Genes , Potencial de la Membrana Mitocondrial , Ratones , Ratones Noqueados , Proteínas Mitocondriales/metabolismo , Daño por Reperfusión Miocárdica/genética , Daño por Reperfusión Miocárdica/metabolismo , Daño por Reperfusión Miocárdica/patología , Proteínas Sensoras del Calcio Neuronal/metabolismo , Neuropéptidos/metabolismo , Estrés Oxidativo , Consumo de Oxígeno , Transducción de SeñalRESUMEN
Cardiac hypertrophy is a leading cause of serious heart diseases. Although many signaling molecules are involved in hypertrophy, the functions of some proteins in this process are still unknown. Calcineurin B homologous protein 3 (CHP3)/tescalcin is an EF-hand Ca(2+)-binding protein that is abundantly expressed in the heart; however, the function of CHP3 is unclear. Here, we aimed to identify the cardiac functions of CHP3. CHP3 was expressed in hearts at a wide range of developmental stages and was specifically detected in neonatal rat ventricular myocytes (NRVMs) but not in cardiac fibroblasts in culture. Moreover, knockdown of CHP3 expression using adenoviral-based RNA interference in NRVMs resulted in enlargement of cardiomyocyte size, concomitant with increased expression of a pathological hypertrophy marker ANP. This same treatment elevated glycogen synthase kinase (GSK3α/ß) phosphorylation, which is known to inhibit GSK3 function. In contrast, CHP3 overexpression blocked the insulin-induced phosphorylation of GSK3α/ß without affecting the phosphorylation of Akt, which is an upstream kinase of GSK3α/ß, in HEK293 cells, and it inhibited both IGF-1-induced phosphorylation of GSK3ß and cardiomyocyte hypertrophy in NRVMs. Co-immunoprecipitation experiments revealed that GSK3ß interacted with CHP3. However, a Ca(2+)-binding-defective mutation of CHP3 (CHP3-D123A) also interacted with GSK3ß and had the same inhibitory effect on GSK3α/ß phosphorylation, suggesting that the action of CHP3 was independent of Ca(2+). These findings suggest that CHP3 functions as a novel negative regulator of cardiomyocyte hypertrophy via inhibition of GSK3α/ß phosphorylation and subsequent enzymatic activation of GSK3α/ß.
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Proteínas de Unión al Calcio/metabolismo , Glucógeno Sintasa Quinasa 3/metabolismo , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patología , Animales , Animales Recién Nacidos , Sitios de Unión , Calcio/metabolismo , Técnicas de Silenciamiento del Gen , Glucógeno Sintasa Quinasa 3 beta , Células HEK293 , Humanos , Hipertrofia , Inmunoprecipitación , Insulina/farmacología , Factor I del Crecimiento Similar a la Insulina/farmacología , Proteínas Mutantes/metabolismo , Miocardio/metabolismo , Miocitos Cardíacos/efectos de los fármacos , Fosforilación/efectos de los fármacos , Proteínas Proto-Oncogénicas c-akt/metabolismo , RatasRESUMEN
In cardiomyocytes, intracellular calcium (Ca2+) transients are elicited by electrical and receptor stimulations, leading to muscle contraction and gene expression, respectively. Although such elevations of Ca2+levels ([Ca2+]) also occur in the nucleus, the precise mechanism of nuclear [Ca2+] regulation during different kinds of stimuli, and its relationship with cytoplasmic [Ca2+] regulation are not fully understood. To address these issues, we used a new region-specific fluorescent protein-based Ca2+ indicator, GECO, together with the conventional probe Fluo-4 AM. We confirmed that nuclear Ca2+ transients were elicited by both electrical and receptor stimulations in neonatal mouse ventricular myocytes. Kinetic analysis revealed that electrical stimulation-elicited nuclear Ca2+ transients are slower than cytoplasmic Ca2+ transients, and chelating cytoplasmic Ca2+ abolished nuclear Ca2+ transients, suggesting that nuclear Ca2+ are mainly derived from the cytoplasm during electrical stimulation. On the other hand, receptor stimulation such as with insulin-like growth factor-1 (IGF-1) preferentially increased nuclear [Ca2+] compared to cytoplasmic [Ca2+]. Experiments using inhibitors revealed that electrical and receptor stimulation-elicited Ca2+ transients were mainly mediated by ryanodine receptors and inositol 1,4,5-trisphosphate receptors (IP3Rs), respectively, suggesting different mechanisms for the two signals. Furthermore, IGF-1-elicited nuclear Ca2+ transient amplitude was significantly lower in myocytes lacking neuronal Ca2+ sensor-1 (NCS-1), a Ca2+ binding protein implicated in IP3R-mediated pathway in the heart. Moreover, IGF-1 strengthened the interaction between NCS-1 and IP3R. These results suggest a novel mechanism for receptor stimulation-induced nuclear [Ca2+] regulation mediated by IP3R and NCS-1 that may further fine-tune cardiac Ca2+ signal regulation.
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Calcio/metabolismo , Receptores de Inositol 1,4,5-Trifosfato/genética , Factor I del Crecimiento Similar a la Insulina/farmacología , Miocitos Cardíacos/metabolismo , Proteínas Sensoras del Calcio Neuronal/genética , Neuropéptidos/genética , Compuestos de Anilina , Animales , Animales Recién Nacidos , Señalización del Calcio , Núcleo Celular/efectos de los fármacos , Núcleo Celular/metabolismo , Citoplasma/efectos de los fármacos , Citoplasma/metabolismo , Estimulación Eléctrica , Colorantes Fluorescentes , Regulación de la Expresión Génica , Ventrículos Cardíacos/citología , Ventrículos Cardíacos/efectos de los fármacos , Ventrículos Cardíacos/metabolismo , Receptores de Inositol 1,4,5-Trifosfato/metabolismo , Transporte Iónico , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Miocitos Cardíacos/citología , Miocitos Cardíacos/efectos de los fármacos , Proteínas Sensoras del Calcio Neuronal/deficiencia , Neuropéptidos/deficiencia , Cultivo Primario de Células , Canal Liberador de Calcio Receptor de Rianodina/genética , Canal Liberador de Calcio Receptor de Rianodina/metabolismo , XantenosRESUMEN
In patients receiving allogeneic hematopoietic cell transplantation, chronic graft-versus-host disease (cGVHD) remains a frequent complication and resembles autoimmune diseases such as systemic lupus erythematosus and systemic sclerosis. Our previous work demonstrated the critical role of CD28 costimulation of donor T cells for GVHD induction. In this study, we investigate the role of CD28 costimulation of host T cells in cGVHD. CD28-intact mice as hosts showed systemic lupus erythematosus-type cGVHD, whereas CD28-deficient mice developed a distinct phenotype of cGVHD, with fibrotic damage in skin and internal organs, resembling systemic sclerosis. This phenotype was due to a lack of signaling through the C-terminal proline-rich motif within host CD28's cytoplasmic tail, a motif previously shown to be required for development of regulatory T cells (Tregs) and function of conventional T cells. Adoptive transfer experiments demonstrated that a defect in host CD4(+)CD25(+) Tregs, but not in conventional T cells, was responsible for disease phenotype. Host Treg deficiency altered the cytokine pattern of donor CD4(+) T cells and the Ag specificity of autoantibodies, and these might lead to phenotypic change. Thus, host CD28 signaling controlled the pathogenesis of cGVHD through effects on host Tregs, whose status impacts qualitatively on the allogeneic immune responses.
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Antígenos CD28/deficiencia , Enfermedad Injerto contra Huésped/inmunología , Linfocitos T Reguladores/inmunología , Animales , Antígenos CD28/genética , Antígenos CD28/inmunología , Enfermedad Crónica , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones Transgénicos , Linfocitos T Reguladores/metabolismo , Trasplante HomólogoRESUMEN
Lipid droplet (LD) is a ubiquitous organelle that stores triacylglycerol and other neutral lipids. Perilipin 5 (Plin5), a member of the perilipin protein family that is abundantly expressed in the heart, is essential to protect LDs from attack by lipases, including adipose triglyceride lipase. Plin5 controls heart metabolism and performance by maintaining LDs under physiological conditions. Aberrant lipid accumulation in the heart leads to organ malfunction, or cardiomyopathy. To elucidate the role of Plin5 in a metabolically disordered state and the mechanism of lipid-induced cardiomyopathy, we studied the effects of streptozotocin-induced type 1 diabetes in Plin5-knockout (KO) mice. In contrast to diabetic wild-type mice, diabetic Plin5-KO mice lacked detectable LDs in the heart and did not exhibit aberrant lipid accumulation, excessive reactive oxygen species (ROS) generation, or heart malfunction. Moreover, diabetic Plin5-KO mice exhibited lower heart levels of lipotoxic molecules, such as diacylglycerol and ceramide, than wild-type mice. Membrane translocation of protein kinase C and the assembly of NADPH oxidase 2 complex on the membrane were also suppressed. The results suggest that diabetic Plin5-KO mice are resistant to type 1 diabetes-induced heart malfunction due to the suppression of the diacylglycerol/ceramide-protein kinase C pathway and of excessive ROS generation by NADPH oxidase.
Asunto(s)
Cardiomiopatías/prevención & control , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Tipo 1/patología , Gotas Lipídicas/metabolismo , Miocardio/metabolismo , Proteínas/genética , Proteínas/metabolismo , Triglicéridos/metabolismo , Animales , Cardiomiopatías/complicaciones , Ceramidas/metabolismo , Diabetes Mellitus Experimental/patología , Diabetes Mellitus Tipo 1/inducido químicamente , Diabetes Mellitus Tipo 1/metabolismo , Diglicéridos/metabolismo , Glicoproteínas de Membrana/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , NADPH Oxidasa 2 , NADPH Oxidasas/metabolismo , Perilipina-5 , Proteína Quinasa C/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Transducción de Señal , EstreptozocinaRESUMEN
The plasma membrane Na(+)/H(+) exchanger 1 (NHE1) is rapidly activated in response to various stimuli. The membrane-proximal cytoplasmic region (â¼60 residues), termed the lipid-interacting domain (LID), is an important regulatory domain of NHE1. Here, we used a pharmacological approach to further characterize the role of LID in the regulation of NHE1. Pharmacological analysis using staurosporine-like indolocarbazole and bisindolylmaleimide compounds suggested that the phorbol ester- and receptor agonist-induced activation of NHE1 occurs through a protein kinase C-independent mechanism. In particular, only indolocarbazole compounds that inhibited NHE1 activation were able to interact with the LID, suggesting that the inhibition of NHE1 activation is achieved through the direct action of these compounds on the LID. Furthermore, in addition to phorbol esters and a receptor agonist, okadaic acid and hyperosmotic stress, which are known to activate NHE1 through unknown mechanisms, were found to promote membrane association of the LID concomitant with NHE1 activation; these effects were inhibited by staurosporine, as well as by a mutation in the LID. Binding experiments using the fluorescent ATP analog trinitrophenyl ATP revealed that ATP and the NHE1 activator phosphatidylinositol 4,5-bisphosphate bind competitively to the LID. These findings suggest that modulation of NHE1 activity by various activators and inhibitors occurs through the direct binding of these molecules to the LID, which alters the association of the LID with the plasma membrane.
Asunto(s)
Carbazoles/farmacología , Proteínas de Transporte de Catión/metabolismo , Indoles/farmacología , Lípidos/química , Maleimidas/farmacología , Inhibidores de Proteínas Quinasas/farmacología , Intercambiadores de Sodio-Hidrógeno/metabolismo , Agonistas de Receptores Adrenérgicos alfa 1/farmacología , Animales , Unión Competitiva , Carbazoles/química , Proteínas de Transporte de Catión/antagonistas & inhibidores , Proteínas de Transporte de Catión/química , Proteínas de Transporte de Catión/genética , Membrana Celular , Cricetinae , Cricetulus , Bases de Datos de Compuestos Químicos , Indoles/química , Maleimidas/química , Ratones , Mutación , Ácido Ocadaico/farmacología , Presión Osmótica , Fosfatidilinositol 4,5-Difosfato/farmacología , Proteína Quinasa C/antagonistas & inhibidores , Proteína Quinasa C/metabolismo , Inhibidores de Proteínas Quinasas/química , Estructura Terciaria de Proteína , Transporte de Proteínas , Receptores Adrenérgicos alfa 1/genética , Receptores Adrenérgicos alfa 1/metabolismo , Intercambiador 1 de Sodio-Hidrógeno , Intercambiadores de Sodio-Hidrógeno/antagonistas & inhibidores , Intercambiadores de Sodio-Hidrógeno/química , Intercambiadores de Sodio-Hidrógeno/genética , Estaurosporina/química , Estaurosporina/farmacología , TransfecciónRESUMEN
The Na(+) gradient produced across the cardiac sarcolemma by the ATP-dependent Na(+)-pump is a constant source of energy for Na(+)-dependent transporters. The plasma membrane Na(+)/H(+) exchanger (NHE) is one such secondary active transporter, regulating intracellular pH, Na(+) concentration, and cell volume. NHE1, the major isoform found in the heart, is activated in response to a variety of stimuli such as hormones and mechanical stress. This important characteristic of NHE1 is intimately linked to heart diseases, including maladaptive cardiac hypertrophy and subsequent heart failure, as well as acute ischemic-reperfusion injury. NHE1 activation results in elevation of pH and intracellular Na(+) concentration, which potentially enhance downstream signaling cascades in the myocardium. Therefore, in addition to determining the mechanism underlying regulation of NHE1 activity, it is important to understand how the ionic signal produced by NHE1 is transmitted to the downstream targets. Extensive studies have identified many accessory factors that interact with NHE1. Here, we have summarized the recent progress on understanding the molecular mechanism underlying NHE1 regulation and have shown a possible signaling pathway leading to cardiac remodeling, which is initiated from NHE1. This article is part of a Special Issue entitled "Na(+) Regulation in Cardiac Myocytes".
Asunto(s)
Cardiomegalia/metabolismo , Proteínas de Transporte de Catión/metabolismo , Insuficiencia Cardíaca/metabolismo , Intercambiadores de Sodio-Hidrógeno/metabolismo , Secuencia de Aminoácidos , Animales , Calcineurina/metabolismo , Calmodulina/metabolismo , Proteínas de Transporte de Catión/química , Humanos , Metabolismo de los Lípidos , Estructura Secundaria de Proteína , Estructura Terciaria de Proteína , Transducción de Señal , Intercambiador 1 de Sodio-Hidrógeno , Intercambiadores de Sodio-Hidrógeno/químicaRESUMEN
Na(+)/H(+) exchanger (NHE) 1 is a member of the solute carrier superfamily, which regulates intracellular ionic homeostasis. NHE1 is known to require cellular ATP for its activity, despite there being no requirement for energy input from ATP hydrolysis. In this study, we investigated whether NHE1 is an ATP-binding protein. We designed a baculovirus vector carrying both epitope-tagged NHE1 and its cytosolic subunit CHP1, and expressed the functional NHE1-CHP1 complex on the surface of Sf9 insect cells. Using the purified complex protein consisting of NHE1 and CHP1 from Sf9 cells, we examined a photoaffinity labeling reaction with 8-azido-ATP-biotin. UV irradiation promoted the incorporation of 8-azido-ATP into NHE1, but not into CHP1, with an apparent Kd of 29.1 µM in the presence of Mg(2+). The nonlabeled nucleotides ATP, GTP, TTP and CTP all inhibited this crosslinking. However, ATP had the strongest inhibitory effect, with an apparent inhibition constant (IC50) for ATP of 2.2 mM, close to the ATP concentration giving the half-maximal activation of NHE1 activity. Importantly, crosslinking was more strongly inhibited by ATP than by ADP, suggesting that ATP is dissociated from NHE1 upon ATP hydrolysis. Limited proteolysis with thrombin and deletion mutant analysis revealed that the 8-azido-ATP-binding site is within the C-terminal cytoplasmic domain of NHE1. Equilibrium dialysis with NHE1-derived peptides provided evidence that ATP directly binds to the proximal cytoplasmic region (Gly542-Pro598), which is critical for ATP-dependent regulation of NHE1. These findings suggest that NHE1 is an ATP-binding transporter. Thus, ATP may serve as a direct activator of NHE1.