RESUMEN
The orphan nuclear receptor ERRα is the most extensively researched member of the estrogen-related receptor family and holds a pivotal role in various functions associated with energy metabolism, especially in tissues characterized by high energy requirements, such as the heart, skeletal muscle, adipose tissue, kidney, and brain. Abscisic acid (ABA), traditionally acknowledged as a plant stress hormone, is detected and actively functions in organisms beyond the land plant kingdom, encompassing cyanobacteria, fungi, algae, protozoan parasites, lower Metazoa, and mammals. Its ancient, cross-kingdom role enables ABA and its signaling pathway to regulate cell responses to environmental stimuli in various organisms, such as marine sponges, higher plants, and humans. Recent advancements in understanding the physiological function of ABA and its mammalian receptors in governing energy metabolism and mitochondrial function in myocytes, adipocytes, and neuronal cells suggest potential therapeutic applications for ABA in pre-diabetes, diabetes, and cardio-/neuroprotection. The ABA/LANCL1-2 hormone/receptor system emerges as a novel regulator of ERRα expression levels and transcriptional activity, mediated through the AMPK/SIRT1/PGC-1α axis. There exists a reciprocal feed-forward transcriptional relationship between the LANCL proteins and transcriptional coactivators ERRα/PGC-1α, which may be leveraged using natural or synthetic LANCL agonists to enhance mitochondrial function across various clinical contexts.
Asunto(s)
Ácido Abscísico , Receptor Relacionado con Estrógeno ERRalfa , Metabolismo Energético , Receptores de Estrógenos , Receptores de Estrógenos/metabolismo , Humanos , Animales , Ácido Abscísico/metabolismo , Transducción de Señal , Factores de Transcripción/metabolismo , Factores de Transcripción/genéticaRESUMEN
Abscisic acid (ABA), long known as a plant stress hormone, is present and functionally active in organisms other than those pertaining to the land plant kingdom, including cyanobacteria, fungi, algae, protozoan parasites, lower Metazoa, and mammals. The ancient, cross-kingdom role of this stress hormone allows ABA and its signaling pathway to control cell responses to environmental stimuli in diverse organisms such as marine sponges, higher plants, and humans. Recent advances in our knowledge about the physiological role of ABA and of its mammalian receptors in the control of energy metabolism and mitochondrial function in myocytes, adipocytes, and neuronal cells allow us to foresee therapeutic applications for ABA in the fields of pre-diabetes, diabetes, and cardio- and neuro-protection. Vegetal extracts titrated in their ABA content have shown both efficacy and tolerability in preliminary clinical studies. As the prevalence of glucose intolerance, diabetes, and cardiovascular and neurodegenerative diseases is steadily increasing in both industrialized and rapidly developing countries, new and cost-efficient therapeutics to combat these ailments are much needed to ensure disease-free aging for the current and future working generations.
Asunto(s)
Diabetes Mellitus , Embryophyta , Animales , Humanos , Ácido Abscísico/metabolismo , Miocitos Cardíacos/metabolismo , Neuroprotección , Diabetes Mellitus/tratamiento farmacológico , Reguladores del Crecimiento de las Plantas/fisiología , Embryophyta/metabolismo , Hormonas , Mamíferos/metabolismoRESUMEN
The abscisic acid (ABA)/LANC-like protein 1/2 (LANCL1/2) hormone/receptor system regulates glucose uptake and oxidation, mitochondrial respiration, and proton gradient dissipation in myocytes. Oral ABA increases glucose uptake and the transcription of adipocyte browning-related genes in rodent brown adipose tissue (BAT). The aim of this study was to investigate the role of the ABA/LANCL system in human white and brown adipocyte thermogenesis. Immortalized human white and brown preadipocytes, virally infected to overexpress or silence LANCL1/2, were differentiated in vitro with or without ABA, and transcriptional and metabolic targets critical for thermogenesis were explored. The overexpression of LANCL1/2 increases, and their combined silencing conversely reduces mitochondrial number, basal, and maximal respiration rates; proton gradient dissipation; and the transcription of uncoupling genes and of receptors for thyroid and adrenergic hormones, both in brown and in white adipocytes. The transcriptional enhancement of receptors for browning hormones also occurs in BAT from ABA-treated mice, lacking LANCL2 but overexpressing LANCL1. The signaling pathway downstream of the ABA/LANCL system includes AMPK, PGC-1α, Sirt1, and the transcription factor ERRα. The ABA/LANCL system controls human brown and "beige" adipocyte thermogenesis, acting upstream of a key signaling pathway regulating energy metabolism, mitochondrial function, and thermogenesis.
Asunto(s)
Ácido Abscísico , Protones , Animales , Humanos , Ratones , Ácido Abscísico/metabolismo , Adipocitos Marrones/metabolismo , Tejido Adiposo Pardo/metabolismo , Tejido Adiposo Blanco/metabolismo , Metabolismo Energético/genética , Glucosa/metabolismo , Hormonas/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Termogénesis/genética , Proteína Desacopladora 1/metabolismoRESUMEN
INTRODUCTION: The potential efficacy of selected plant extracts to counteract the dermal toxicity of jellyfish envenomation was investigated using an in vitro cell culture model. METHODS: We studied plant extracts from Carica papaya, Ananas comosus, and Bouvardia ternifolia, known for their antivenom properties, in pairwise combinations with tissue homogenates of the jellyfish Pelagia noctiluca, Phyllorhiza punctata, and Cassiopea andromeda, to evaluate modulations of jellyfish cytotoxic effects. L929 mouse fibroblasts were incubated with pairwise jellyfish/plant extract combinations and examined by MTT assay (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide). RESULTS: C papaya and A comosus significantly lowered the cytotoxicity of P noctiluca and P punctata but induced a slight worsening of C andromeda cytotoxicity. Conversely, B ternifolia was protective against P punctata, ineffective against P noctiluca, and worsened C andromeda cytotoxicity. CONCLUSIONS: Data showed species-specific and contrasting effects of plant extracts, suggesting that those containing protease activities, namely A comosus and C papaya, are more effective in lowering the cytotoxicity of jellyfish venom containing toxic peptidic factors such as phospholipase A. However, all examined plants require further investigation in vivo to evaluate their ability to counteract jellyfish injury to the skin.
Asunto(s)
Antivenenos/farmacología , Venenos de Cnidarios/efectos adversos , Extractos Vegetales/farmacología , Escifozoos/efectos de los fármacos , Ananas/química , Animales , Antivenenos/química , Carica/química , Ratones , Extractos Vegetales/química , Rubiaceae/química , Sales de Tetrazolio , TiazolesRESUMEN
The natural composition of nutrients present in food is a key factor determining the immune function and stress responses in the honeybee (Apis mellifera). We previously demonstrated that a supplement of abscisic acid (ABA), a natural component of nectar, pollen, and honey, increases honeybee colony survival overwinter. Here we further explored the role of ABA in in vitro-reared larvae exposed to low temperatures. Four-day-old larvae (L4) exposed to 25°C for 3 days showed lower survival rates and delayed development compared to individuals growing at a standard temperature (34°C). Cold-stressed larvae maintained higher levels of ABA for longer than do larvae reared at 34°C, suggesting a biological significance for ABA. Larvae fed with an ABA-supplemented diet completely prevent the low survival rate due to cold stress and accelerate adult emergence. ABA modulates the expression of genes involved in metabolic adjustments and stress responses: Hexamerin 70b, Insulin Receptor Substrate, Vitellogenin, and Heat Shock Proteins 70. AmLANCL2, the honeybee ABA receptor, is also regulated by cold stress and ABA. These results support a role for ABA increasing the tolerance of honeybee larvae to low temperatures through priming effects.
Asunto(s)
Ácido Abscísico/administración & dosificación , Abejas/fisiología , Frío , Animales , Larva/fisiologíaRESUMEN
Abscisic acid (ABA) is a plant hormone also present in animals, where it is involved in the regulation of innate immune cell function and of glucose disposal, through its receptor LANCL2. ABA stimulates glucose uptake by myocytes and pre-adipocytes in vitro and oral ABA improves glycemic control in rats and in healthy subjects. Here we investigated the role of the ABA/LANCL2 system in the regulation of glucose uptake and metabolism in adipocytes. Silencing of LANCL2 abrogated both the ABA- and insulin-induced increase of glucose transporter-4 expression and of glucose uptake in differentiated 3T3-L1 murine adipocytes; conversely, overexpression of LANCL2 enhanced basal, ABA- and insulin-stimulated glucose uptake. As compared with insulin, ABA treatment of adipocytes induced lower triglyceride accumulation, CO2 production and glucose-derived fatty acid synthesis. ABA per se did not induce pre-adipocyte differentiation in vitro, but stimulated adipocyte remodeling in terminally differentiated cells, with a reduction in cell size, increased mitochondrial content, enhanced O2 consumption, increased transcription of adiponectin and of brown adipose tissue (BAT) genes. A single dose of oral ABA (1µg/kg body weight) increased BAT glucose uptake 2-fold in treated rats compared with untreated controls. One-month-long ABA treatment at the same daily dose significantly upregulated expression of BAT markers in the WAT and in WAT-derived preadipocytes from treated mice compared with untreated controls. These results indicate a hitherto unknown role of LANCL2 in adipocyte sensitivity to insulin-stimulated glucose uptake and suggest a role for ABA in the induction and maintenance of BAT activity.
Asunto(s)
Ácido Abscísico/farmacología , Adipocitos/efectos de los fármacos , Tejido Adiposo Pardo/efectos de los fármacos , Tejido Adiposo Pardo/metabolismo , Glucosa/metabolismo , Células 3T3-L1 , Adipocitos/metabolismo , Animales , Biomarcadores/metabolismo , Glucemia/efectos de los fármacos , Glucemia/metabolismo , Diferenciación Celular/efectos de los fármacos , Línea Celular , Transportador de Glucosa de Tipo 4/metabolismo , Humanos , Insulina/metabolismo , Masculino , Ratones , Células Musculares/efectos de los fármacos , Células Musculares/metabolismo , Ratas , Ratas Wistar , Transcripción Genética/efectos de los fármacosRESUMEN
Abscisic acid (ABA) is a plant hormone involved in the response to environmental stress. Recently, ABA has been shown to be present and active also in mammals, where it stimulates the functional activity of innate immune cells, of mesenchymal and hemopoietic stem cells, and insulin-releasing pancreatic ß-cells. LANCL2, the ABA receptor in mammalian cells, is a peripheral membrane protein that localizes at the intracellular side of the plasma membrane. Here we investigated the mechanism enabling ABA transport across the plasmamembrane of human red blood cells (RBC). Both influx and efflux of [(3)H]ABA occur across intact RBC, as detected by radiometric and chromatographic methods. ABA binds specifically to Band 3 (the RBC anion transporter), as determined by labeling of RBC membranes with biotinylated ABA. Proteoliposomes reconstituted with human purified Band 3 transport [(3)H]ABA and [(35)S]sulfate, and ABA transport is sensitive to the specific Band 3 inhibitor 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid. Once inside RBC, ABA stimulates ATP release through the LANCL2-mediated activation of adenylate cyclase. As ATP released from RBC is known to exert a vasodilator response, these results suggest a role for plasma ABA in the regulation of vascular tone.
Asunto(s)
Ácido Abscísico/farmacología , Proteína 1 de Intercambio de Anión de Eritrocito/metabolismo , Transporte Biológico/efectos de los fármacos , Membrana Celular/metabolismo , Eritrocitos/efectos de los fármacos , Eritrocitos/metabolismo , Reguladores del Crecimiento de las Plantas/farmacología , Ácido 4,4'-Diisotiocianostilbeno-2,2'-Disulfónico/farmacología , Proteína 1 de Intercambio de Anión de Eritrocito/antagonistas & inhibidores , Western Blotting , Células Cultivadas , Cloruros/metabolismo , Cromatografía Líquida de Alta Presión , Humanos , Transducción de SeñalRESUMEN
Inhalation of quartz induces silicosis, a lung disease where alveolar macrophages release inflammatory mediators, including prostaglandin-E(2) (PGE(2)) and tumor necrosis factor α (TNF-α). Here we report the pivotal role of abscisic acid (ABA), a recently discovered human inflammatory hormone, in silica-induced activation of murine RAW264.7 macrophages and of rat alveolar macrophages (AMs). Stimulation of both RAW264.7 cells and AMs with quartz induced a significant increase of ABA release (5- and 10-fold, respectively), compared to untreated cells. In RAW264.7 cells, autocrine ABA released after quartz stimulation sequentially activates the plasma membrane receptor LANCL2 and NADPH oxidase, generating a Ca(2+) influx resulting in NFκ B nuclear translocation and PGE(2) and TNF-α release (3-, 2-, and 3.5-fold increase, respectively, compared to control, unstimulated cells). Quartz-stimulated RAW264.7 cells silenced for LANCL2 or preincubated with a monoclonal antibody against ABA show an almost complete inhibition of NFκ B nuclear translocation and PGE(2) and TNF-α release compared to controls electroporated with a scramble oligonucleotide or preincubated with an unrelated antibody. AMs showed similar early and late ABA-induced responses as RAW264.7 cells. These findings identify ABA and LANCL2 as key mediators in quartz-induced inflammation, providing possible new targets for antisilicotic therapy.
Asunto(s)
Ácido Abscísico/farmacología , Activación de Macrófagos/efectos de los fármacos , Macrófagos/efectos de los fármacos , Proteínas de la Membrana/metabolismo , Cuarzo/farmacología , Receptores de Superficie Celular/metabolismo , Ácido Abscísico/metabolismo , Ácido Abscísico/fisiología , Transporte Activo de Núcleo Celular/efectos de los fármacos , Animales , Comunicación Autocrina/fisiología , Western Blotting , Calcio/metabolismo , Línea Celular , Núcleo Celular/efectos de los fármacos , Núcleo Celular/metabolismo , Células Cultivadas , Ciclooxigenasa 2/metabolismo , Dinoprostona/metabolismo , Activación Enzimática/efectos de los fármacos , Peroxidación de Lípido/efectos de los fármacos , Macrófagos/citología , Macrófagos/metabolismo , Macrófagos Alveolares/citología , Macrófagos Alveolares/efectos de los fármacos , Macrófagos Alveolares/metabolismo , Proteínas de la Membrana/genética , Ratones , NADPH Oxidasas/metabolismo , FN-kappa B/metabolismo , Proteínas de Unión a Fosfato , Interferencia de ARN , Ratas , Receptores de Superficie Celular/genética , Factor de Necrosis Tumoral alfa/metabolismo , terc-Butilhidroperóxido/farmacologíaRESUMEN
The plant hormone abscisic acid (ABA) is released from glucose-challenged human pancreatic ß cells and stimulates insulin secretion. We investigated whether plasma ABA increased during oral and intravenous glucose tolerance tests (OGTTs and IVGTTs) in healthy human subjects. In all subjects undergoing OGTTs (n=8), plasma ABA increased over basal values (in a range from 2- to 9-fold). A positive correlation was found between the ABA area under the curve (AUC) and the glucose AUC. In 4 out of 6 IVGTTs, little or no increase of ABA levels was observed. In the remaining subjects, the ABA increase was similar to that recorded during OGTTs. GLP-1 stimulated ABA release from an insulinoma cell line and from human islets, by â¼10- and 2-fold in low and high glucose, respectively. Human adipose tissue also released ABA in response to high glucose. Nanomolar ABA stimulated glucose uptake, similarly to insulin, in rat L6 myoblasts and in murine 3T3-L1 cells differentiated to adipocytes, by increasing GLUT-4 translocation to the plasma membrane. Demonstration that a glucose load in humans is followed by a physiological rise of plasma ABA, which can enhance glucose uptake by adipose tissues and muscle cells, identifies ABA as a new mammalian hormone involved in glucose metabolism.
Asunto(s)
Ácido Abscísico/sangre , Adipocitos/efectos de los fármacos , Glucosa/farmacología , Hiperglucemia/sangre , Mioblastos/efectos de los fármacos , Células 3T3-L1 , Ácido Abscísico/metabolismo , Adipocitos/citología , Adipocitos/metabolismo , Tejido Adiposo/citología , Tejido Adiposo/metabolismo , Adolescente , Adulto , Animales , Glucemia/metabolismo , Western Blotting , Línea Celular Tumoral , Diabetes Mellitus Tipo 1/sangre , Femenino , Citometría de Flujo , Receptor del Péptido 1 Similar al Glucagón , Glucosa/farmacocinética , Prueba de Tolerancia a la Glucosa , Transportador de Glucosa de Tipo 4/metabolismo , Humanos , Ratones , Persona de Mediana Edad , Mioblastos/citología , Mioblastos/metabolismo , Interferencia de ARN , Receptores de Glucagón/genética , Receptores de Glucagón/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Adulto JovenRESUMEN
The cross-kingdom stress hormone abscisic acid (ABA) and its mammalian receptors LANCL1 and LANCL2 regulate the response of cardiomyocytes to hypoxia by activating NO generation. The overexpression of LANCL1/2 increases transcription, phosphorylation and the activity of eNOS and improves cell vitality after hypoxia/reoxygenation via the AMPK/PGC-1α axis. Here, we investigated whether the ABA/LANCL system also affects the mitochondrial oxidative metabolism and structural proteins. Mitochondrial function, cell cycle and the expression of cytoskeletal, contractile and ion channel proteins were studied in H9c2 rat cardiomyoblasts overexpressing or silenced by LANCL1 and LANCL2, with or without ABA. Overexpression of LANCL1/2 significantly increased, while silencing conversely reduced the mitochondrial number, OXPHOS complex I, proton gradient, glucose and palmitate-dependent respiration, transcription of uncoupling proteins, expression of proteins involved in cytoskeletal, contractile and electrical functions. These effects, and LANCL1/2-dependent NO generation, are mediated by transcription factor ERRα, upstream of the AMPK/PGC1-α axis and transcriptionally controlled by the LANCL1/2-ABA system. The ABA-LANCL1/2 hormone-receptor system controls fundamental aspects of cardiomyocyte physiology via an ERRα/AMPK/PGC-1α signaling axis and ABA-mediated targeting of this axis could improve cardiac function and resilience to hypoxic and dysmetabolic conditions.
RESUMEN
UV-B is an abiotic environmental stress in both plants and animals. Abscisic acid (ABA) is a phytohormone regulating fundamental physiological functions in plants, including response to abiotic stress. We previously demonstrated that ABA is an endogenous stress hormone also in animal cells. Here, we investigated whether autocrine ABA regulates the response to UV-B of human granulocytes and keratinocytes, the cells involved in UV-triggered skin inflammation. The intracellular ABA concentration increased in UV-B-exposed granulocytes and keratinocytes and ABA was released into the supernatant. The UV-B-induced production of NO and of reactive oxygen species (ROS), phagocytosis, and cell migration were strongly inhibited in granulocytes irradiated in the presence of a monoclonal antibody against ABA. Moreover, presence of the same antibody strongly inhibited release of NO, prostaglandin E2 (PGE(2)), and tumor necrosis factor-α (TNF-α) by UV-B irradiated keratinocytes. Lanthionine synthetase C-like protein 2 (LANCL2) is required for the activation of the ABA signaling pathway in human granulocytes. Silencing of LANCL2 in human keratinocytes by siRNA was accompanied by abrogation of the UV-B-triggered release of PGE(2), TNF-α, and NO and ROS production. These results indicate that UV-B irradiation induces ABA release from human granulocytes and keratinocytes and that autocrine ABA stimulates cell functions involved in skin inflammation.
Asunto(s)
Ácido Abscísico/metabolismo , Comunicación Autocrina , Dermatitis/etiología , Granulocitos/efectos de la radiación , Queratinocitos/efectos de la radiación , Rayos Ultravioleta , Línea Celular , Quimiotaxis de Leucocito , Medios de Cultivo Condicionados/metabolismo , Dermatitis/metabolismo , Dinoprostona/metabolismo , Relación Dosis-Respuesta en la Radiación , Granulocitos/metabolismo , Humanos , Mediadores de Inflamación/metabolismo , Queratinocitos/metabolismo , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Óxido Nítrico/metabolismo , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Fagocitosis , Proteínas de Unión a Fosfato , Interferencia de ARN , Especies Reactivas de Oxígeno/metabolismo , Factores de Tiempo , Transfección , Factor de Necrosis Tumoral alfa/metabolismo , Regulación hacia ArribaRESUMEN
Abscisic acid (ABA), a plant hormone, has recently been shown to play a role in glycemia regulation in mammals, by stimulating insulin-independent glucose uptake and metabolism in skeletal muscle. The aim of this study was to test whether ABA could improve glycemic control in a murine model of type 1 diabetes (T1D). Mice were rendered diabetic with streptozotocin and the effect of ABA administration, alone or with insulin, was tested on glycemia. Diabetic mice treated with a single oral dose of ABA and low-dose subcutaneous insulin showed a significantly reduced glycemia profile compared with controls treated with insulin alone. In diabetic mice treated for four weeks with ABA, the effect of low-dose insulin on the glycemia profile after glucose load was significantly improved, and transcription both of the insulin receptor, and of glycolytic enzymes in muscle, was increased. Moreover, a significantly increased transcription and protein expression of AMPK, PGC1-α, and GLUT4 was observed in the skeletal muscle from diabetic mice treated with ABA, compared with untreated controls. ABA supplementation in conjunction with insulin holds the promise of reducing the dose of insulin required in T1D, reducing the risk of hypoglycemia, and improving muscle insulin sensitivity and glucose consumption.
RESUMEN
ADP-ribosyl cyclases (ADPRCs) catalyze the synthesis of the Ca2+-active second messengers Cyclic ADP-ribose (cADPR) and ADP-ribose (ADPR) from NAD+ as well as nicotinic acid adenine dinucleotide phosphate (NAADP+) from NADP+. The best characterized ADPRC in mammals is CD38, a single-pass transmembrane protein with two opposite membrane orientations. The first identified form, type II CD38, is a glycosylated ectoenzyme, while type III CD38 has its active site in the cytosol. The ectoenzymatic nature of type II CD38 raised long ago the question of a topological paradox concerning the access of the intracellular NAD+ substrate to the extracellular active site and of extracellular cADPR product to its intracellular receptors, ryanodine (RyR) channels. Two different transporters, equilibrative connexin 43 (Cx43) hemichannels for NAD+ and concentrative nucleoside transporters (CNTs) for cADPR, proved to mediate cell-autonomous trafficking of both nucleotides. Here, we discussed how type II CD38, Cx43 and CNTs also play a role in mediating several paracrine processes where an ADPRC+ cell supplies a neighboring CNT-and RyR-expressing cell with cADPR. Recently, type II CD38 was shown to start an ectoenzymatic sequence of reactions from NAD+/ADPR to the strong immunosuppressant adenosine; this paracrine effect represents a major mechanism of acquired resistance of several tumors to immune checkpoint therapy.
Asunto(s)
Fenómenos Biológicos , ADP-Ribosa Cíclica , ADP-Ribosil Ciclasa/metabolismo , ADP-Ribosil Ciclasa 1/metabolismo , Animales , Antígenos CD/metabolismo , Conexina 43/metabolismo , ADP-Ribosa Cíclica/metabolismo , Mamíferos/metabolismo , Glicoproteínas de Membrana/metabolismo , NAD/metabolismoRESUMEN
Abscisic acid (ABA) regulates plant responses to stress, partly via NO. In mammals, ABA stimulates NO production by innate immune cells and keratinocytes, glucose uptake and mitochondrial respiration by skeletal myocytes and improves blood glucose homeostasis through its receptors LANCL1 and LANCL2. We hypothesized a role for the ABA-LANCL1/2 system in cardiomyocyte protection from hypoxia via NO. The effect of ABA and of the silencing or overexpression of LANCL1 and LANCL2 were investigated in H9c2 rat cardiomyoblasts under normoxia or hypoxia/reoxygenation. In H9c2, hypoxia induced ABA release, and ABA stimulated NO production. ABA increased the survival of H9c2 to hypoxia, and L-NAME, an inhibitor of NO synthase (NOS), abrogated this effect. ABA also increased glucose uptake and NADPH levels and increased phosphorylation of Akt, AMPK and eNOS. Overexpression or silencing of LANCL1/2 significantly increased or decreased, respectively, transcription, expression and phosphorylation of AMPK, Akt and eNOS; transcription of NAMPT, Sirt1 and the arginine transporter. The mitochondrial proton gradient and cell vitality increased in LANCL1/2-overexpressing vs. -silenced cells after hypoxia/reoxygenation, and L-NAME abrogated this difference. These results implicate the ABA-LANCL1/2 hormone-receptor system in NO-mediated cardiomyocyte protection against hypoxia.
Asunto(s)
Ácido Abscísico , Miocitos Cardíacos , Proteínas Quinasas Activadas por AMP/metabolismo , Ácido Abscísico/metabolismo , Animales , Glucemia/metabolismo , Hipoxia de la Célula , Hormonas/metabolismo , Proteínas de la Membrana/metabolismo , Miocitos Cardíacos/metabolismo , NADP/metabolismo , NG-Nitroarginina Metil Éster/farmacología , Proteínas Proto-Oncogénicas c-akt/metabolismo , Ratas , Receptores Acoplados a Proteínas G , Sirtuina 1/metabolismoRESUMEN
The phytohormone abscisic acid (ABA), in addition to regulating several important physiological functions in plants, is also produced and released by human granulocytes and monocytes where it stimulates cell activities involved in the innate immune response. Here we describe the properties of an ABA synthetic analog that competes with the hormone for binding to human granulocyte membranes and to purified recombinant LANCL2 (the human ABA receptor) and inhibits several ABA-triggered inflammatory functions of granulocytes and monocytes in vitro: chemotaxis, phagocytosis, reactive oxygen species production and release of prostaglandin E(2) (PGE(2)) by human granulocytes, release of PGE(2) and of monocyte chemoattractant protein-1 by human monocytes. This observation provides a proof of principle that ABA antagonists may represent a new class of anti-inflammatory agents.
Asunto(s)
Ácido Abscísico/análogos & derivados , Antiinflamatorios no Esteroideos/química , Antiinflamatorios no Esteroideos/farmacología , Granulocitos/efectos de los fármacos , Monocitos/efectos de los fármacos , Ácido Abscísico/química , Ácido Abscísico/metabolismo , Ácido Abscísico/farmacología , Unión Competitiva , Membrana Celular/química , Membrana Celular/efectos de los fármacos , Células Cultivadas , Quimiotaxis/efectos de los fármacos , Granulocitos/química , Humanos , Proteínas de la Membrana/química , Monocitos/química , Proteínas Nucleares/química , Fagocitosis/efectos de los fármacos , Proteínas de Unión a Fosfato , Proteínas Recombinantes/química , Relación Estructura-ActividadRESUMEN
The phytohormone abscisic acid (ABA) is the central regulator of abiotic stress in plants and plays important roles during plant growth and development. In animal cells, ABA was shown to be an endogenous hormone, acting as a stress signal and stimulating cell functions involved in inflammatory responses and in insulin release. Recently, we demonstrated that Lanthionine synthetase component C-like protein 2 (LANCL2) is required for ABA binding to the plasmamembrane of granulocytes and for the activation of the signaling pathway triggered by ABA in human granulocytes and in rat insulinoma cells. In order to investigate whether ABA activates LANCL2 via direct interaction, we performed specific binding studies on human LANCL2 recombinant protein using different experimental approaches (saturation binding, scintillation proximity assays, dot blot experiments and affinity chromatography). Altogether, results indicate that human recombinant LANCL2 binds ABA directly and provide the first demonstration of ABA binding to a mammalian ABA receptor.
Asunto(s)
Ácido Abscísico/metabolismo , Proteínas de la Membrana/metabolismo , Proteínas Nucleares/metabolismo , Humanos , Proteínas de la Membrana/química , Proteínas de la Membrana/genética , Proteínas Nucleares/química , Proteínas Nucleares/genética , Proteínas de Unión a Fosfato , Unión Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismoRESUMEN
OBJECTIVE: Abscisic acid (ABA) is a plant hormone also present and active in animals. In mammals, ABA regulates blood glucose levels by stimulating insulin-independent glucose uptake and metabolism in adipocytes and myocytes through its receptor LANCL2. The objective of this study was to investigate whether another member of the LANCL protein family, LANCL1, also behaves as an ABA receptor and, if so, which functional effects are mediated by LANCL1. METHODS: ABA binding to human recombinant LANCL1 was explored by equilibrium-binding experiments with [3H]ABA, circular dichroism, and surface plasmon resonance. Rat L6 myoblasts overexpressing either LANCL1 or LANCL2, or silenced for the expression of both proteins, were used to investigate the basal and ABA-stimulated transport of a fluorescent glucose analog (NBDG) and the signaling pathway downstream of the LANCL proteins using Western blot and qPCR analysis. Finally, glucose tolerance and sensitivity to ABA were compared in LANCL2-/- and wild-type (WT) siblings. RESULTS: Human recombinant LANCL1 binds ABA with a Kd between 1 and 10 µM, depending on the assay (i.e., in a concentration range that lies between the low and high-affinity ABA binding sites of LANCL2). In L6 myoblasts, LANCL1 and LANCL2 similarly, i) stimulate both basal and ABA-triggered NBDG uptake (4-fold), ii) activate the transcription and protein expression of the glucose transporters GLUT4 and GLUT1 (4-6-fold) and the signaling proteins AMPK/PGC-1α/Sirt1 (2-fold), iii) stimulate mitochondrial respiration (5-fold) and the expression of the skeletal muscle (SM) uncoupling proteins sarcolipin (3-fold) and UCP3 (12-fold). LANCL2-/- mice have a reduced glucose tolerance compared to WT. They spontaneously overexpress LANCL1 in the SM and respond to chronic ABA treatment (1 µg/kg body weight/day) with an improved glycemia response to glucose load and an increased SM transcription of GLUT4 and GLUT1 (20-fold) of the AMPK/PGC-1α/Sirt1 pathway and sarcolipin, UCP3, and NAMPT (4- to 6-fold). CONCLUSIONS: LANCL1 behaves as an ABA receptor with a somewhat lower affinity for ABA than LANCL2 but with overlapping effector functions: stimulating glucose uptake and the expression of muscle glucose transporters and mitochondrial uncoupling and respiration via the AMPK/PGC-1α/Sirt1 pathway. Receptor redundancy may have been advantageous in animal evolution, given the role of the ABA/LANCL system in the insulin-independent stimulation of cell glucose uptake and energy metabolism.
Asunto(s)
Proteínas Quinasas Activadas por AMP/metabolismo , Ácido Abscísico/metabolismo , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Sirtuina 1/metabolismo , Glucosa/metabolismo , Células HeLa , Humanos , Mitocondrias/metabolismo , Músculo Esquelético/citología , Músculo Esquelético/metabolismo , Receptores Acoplados a Proteínas G/genéticaRESUMEN
Abscisic acid (ABA) is a plant hormone regulating fundamental physiological functions in plants, such as response to abiotic stress. Recently, ABA was shown to be produced and released by human granulocytes, by insulin-producing rat insulinoma cells, and by human and murine pancreatic beta cells. ABA autocrinally stimulates the functional activities specific for each cell type through a receptor-operated signal transduction pathway, sequentially involving a pertussis toxin-sensitive receptor/G-protein complex, cAMP, CD38-produced cADP-ribose and intracellular calcium. Here we show that the lanthionine synthetase C-like protein LANCL2 is required for ABA binding on the membrane of human granulocytes and that LANCL2 is necessary for transduction of the ABA signal into the cell-specific functional responses in granulocytes and in rat insulinoma cells. Co-expression of LANCL2 and CD38 in the human HeLa cell line reproduces the ABA-signaling pathway. Results obtained with granulocytes and CD38(+)/LANCL2(+) HeLa transfected with a chimeric G-protein (G alpha(q/i)) suggest that the pertussis toxin-sensitive G-protein coupled to LANCL2 is a G(i). Identification of LANCL2 as a critical component of the ABA-sensing protein complex will enable the screening of synthetic ABA antagonists as prospective new anti-inflammatory and anti-diabetic agents.
Asunto(s)
Ácido Abscísico/metabolismo , Granulocitos/metabolismo , Insulinoma/metabolismo , Proteínas de la Membrana/metabolismo , Proteínas Nucleares/metabolismo , Transducción de Señal/fisiología , Animales , Membrana Celular/metabolismo , Movimiento Celular , Células Cultivadas/metabolismo , Granulocitos/citología , Humanos , Insulinoma/genética , Proteínas de la Membrana/genética , N-Glicosil Hidrolasas/genética , N-Glicosil Hidrolasas/metabolismo , Proteínas Nucleares/genética , Fagocitosis/fisiología , Proteínas de Unión a Fosfato , Unión Proteica , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/metabolismo , Ratas , Especies Reactivas de Oxígeno/metabolismoRESUMEN
Abscisic acid (ABA) is a hormone involved in pivotal physiological functions in higher plants, such as response to abiotic stress and control of seed dormancy and germination. Recently, ABA was demonstrated to be autocrinally produced by human granulocytes, beta pancreatic cells, and mesenchymal stem cells (MSC) and to stimulate cell-specific functions through a signaling pathway involving the second messenger cyclic ADP-ribose (cADPR). Here we show that ABA expands human uncommitted hemopoietic progenitors (HP) in vitro, through a cADPR-mediated increase of the intracellular calcium concentration ([Ca(2+)](i)). Incubation of CD34(+) cells with micromolar ABA also induces transcriptional effects, which include NF-kappaB nuclear translocation and transcription of genes encoding for several cytokines. Human MSC stimulated with a lymphocyte-conditioned medium produce and release ABA at concentrations sufficient to exert growth-stimulatory effects on co-cultured CD34(+) cells, as demonstrated by the inhibition of colony growth in the presence of an anti-ABA monoclonal antibody. These results provide a remarkable example of conservation of a stress hormone and of its second messenger from plants to humans and identify ABA as a new hemopoietic growth factor involved in the cross-talk between HP and MSC.
Asunto(s)
Ácido Abscísico/farmacología , Proliferación Celular/efectos de los fármacos , ADP-Ribosa Cíclica/metabolismo , Células Madre Hematopoyéticas/efectos de los fármacos , Sistemas de Mensajero Secundario/fisiología , Ácido Abscísico/metabolismo , Antígenos CD34/metabolismo , Calcio/metabolismo , Señalización del Calcio/efectos de los fármacos , Señalización del Calcio/fisiología , Células Cultivadas , Medios de Cultivo Condicionados/farmacología , Citocinas/efectos de los fármacos , Citocinas/genética , Células Madre Hematopoyéticas/metabolismo , Humanos , Células Madre Mesenquimatosas/metabolismo , FN-kappa B/efectos de los fármacos , FN-kappa B/metabolismo , Neovascularización Fisiológica/fisiología , Reguladores del Crecimiento de las Plantas/farmacología , Sistemas de Mensajero Secundario/efectos de los fármacos , Transducción de Señal/efectos de los fármacos , Transducción de Señal/fisiología , Activación Transcripcional/efectos de los fármacos , Activación Transcripcional/fisiologíaRESUMEN
Abscisic acid (ABA) is a hormone with a very long evolutionary history, dating back to the earliest living organisms, of which modern (ABA-producing) cyanobacteria are likely the descendants, well before separation of the plant and animal kingdoms, with a conserved role as a signal regulating cell responses to environmental challenges. In mammals, nanomolar ABA controls the metabolic response to glucose availability by stimulating glucose uptake in skeletal muscle and adipose tissue with an insulin-independent mechanism and increasing energy expenditure in the brown and white adipose tissues. Activation by ABA of AMP-dependent kinase (AMPK), in contrast to the insulin-induced activation of AMPK-inhibiting Akt, is responsible for stimulation of GLUT4-mediated muscle glucose uptake, and for the browning effect on white adipocytes. Intake of micrograms per Kg body weight of ABA improves glucose tolerance in both normal and in borderline subjects and chronic intake of such a dose of ABA improves blood glucose, lipids and morphometric parameters (waist circumference and body mass index) in borderline subjects for prediabetes and the metabolic syndrome. This review summarizes the most recent results obtained in vivo with microgram amounts of ABA, the role of the receptor LANCL2 in the hormone's action and the significance of the endowment by mammals of two different hormones controlling the metabolic response to glucose availability. Finally, open issues in need of further investigation and perspectives for the clinical use of nutraceutical ABA are discussed.