RESUMEN

Circular RNAs (circRNAs) are a new type of endogenous non-coding RNA formed by a covalent closed loop. CircRNAs are characterized by specificity, universality, conservation, and stability. They are abundant in eukaryotic cells and have biological regulatory roles at various transcriptional and post-transcriptional levels. The upregulation of circPRKCI has been observed in a variety of tumors and is directly related to the clinicopathological characteristics of tumors and prognosis. More importantly, circPRKCI can participate in the tumorigenesis, progression, recurrence, and metastasis of various tumors through many functional mechanisms, including the activation of signaling pathways, such as the phosphatidylinositol-3-kinase (PI3K)/AKT pathway, and sponging of many microRNAs (miRNAs). This review summarizes the progress achieved in understanding the biological functions of circRNA PRKCI in various tumors. The goal is to inform the discovery of more functional mechanisms and new anticancer molecular targets.

RESUMEN

AIMS: To examine the association between daily steps and step intensity with bone health in Chinese community-dwelling older women. METHODS: Data from 1116 women in the Physical Activity and Health in Older Women Study in China, 2021. Three bone parameters: bone quality index (BQI), speed of sound (SOS), and broadband ultrasound attenuation (BUA) were measured in the left heel using an ultrasound bone densitometer and transformed into dichotomous variables from medians. Daily steps and step intensity (slow step time, brisk step time, peak 1-min cadence, peak 30-min cadence, and peak 60-min cadence) were measured using a triaxial accelerometer. Participants with high BQI, SOS, and BUA levels were used as references for logistic regression models to explore the association of daily steps and step intensity with bone health. RESULTS: Daily steps were positively associated with the BQI (odds ratio [OR] = 0.94, confidence interval [CI] = 0.89,1.00), SOS (OR = 0.93, CI = 0.88,0.99), and BUA (OR = 0.93, CI = 0.88,0.99) among older women. There was no significant association between peak cadence and bone health. Slow step time was positively associated with the BQI (OR = 0.94, CI = 0.90,0.99) and SOS (OR = 0.93, CI = 0.88,0.97), while brisk step time was positively associated with the BQI (OR = 0.89, CI = 0.82,0.97), SOS (OR = 0.87, CI = 0.80,0.94), and BUA (OR = 0.89, CI = 0.82,0.97). Moreover, 10,000 steps/day or more was significantly associated with the BQI (OR = 0.52, CI = 0.33,0.81), SOS (OR = 0.55, CI = 0.35,0.86), and BUA (OR = 0.45, CI = 0.28, 0.70) compared to <6000 steps/day. CONCLUSION: Increasing the number of daily steps or the duration of walking, whether fast or slow, may benefit the bone health of older women.

Asunto(s)

Densidad Ósea , Vida Independiente , Humanos , Femenino , Anciano , Estudios Transversales , Caminata , Ultrasonografía , China

RESUMEN

Obesity has become a global pandemic. WDTC1 is a WD40-containing protein that functions as an anti-obesity factor. WDTC1 inhibits adipogenesis by working as an adaptor of the CUL4-DDB1 E3 ligase complex. It remains unclear about how WDTC1 is regulated. Here, we show that the TRiC/CCT functions as a chaperone to facilitate the protein folding of WDTC1 and proper function in adipogenesis. Through tandem purification, we identified the molecular chaperone TRiC/CCT as WDTC1-interacting proteins. WDTC1 bound the TRiC/CCT through its ADP domain, and the TRiC/CCT recognized WDTC1 through the CCT5 subunit. Disruption of the TRiC/CCT by knocking down CCT1 or CCT5 led to misfolding and lysosomal degradation of WDTC1. Furthermore, the knockdown of CCT1 or CCT5 eliminated the inhibitory effect of WDTC1 on adipogenesis. Our studies uncovered a critical role of the TRiC/CCT in the folding of WDTC1 and expanded our knowledge on the regulation of adipogenesis.

RESUMEN

Bee pollen as a plant-derived food is consumed as nutritional/functional supplements by humans. But it might confer foodborne allergenicity in susceptible populations, limiting its extensive application. In this study, five potential allergens including profilin, cystatin, prolamin, expansin, and alcohol dehydrogenase in bee pollen derived from Brassica campestris (BP-Bc), were identified through mass spectrometry-based proteomic analysis. Moreover, different types of enzymes (cellulases, pectases, and papains) serve biological roles in pollen wall breaking and expansion, but also promote allergen release and degradation. Proteomic analysis showed that profilin, cystatin, and alcohol dehydrogenase were significantly reduced in BP-Bc following joint treatment with three enzymes. Metabolomic characterization of potential enzymatic hydrolysates of these significantly-decreased allergens was performed, which showed nine major oligopeptides and six amino acids at significantly higher levels in the enzyme-treated BP-Bc. These findings clarified the culprit responsible for bee pollen allergy and the mechanism of enzymatic desensitization for its further development.

Asunto(s)

Alérgenos , Hipersensibilidad a los Alimentos , Alcohol Deshidrogenasa , Alérgenos/química , Animales , Abejas , Hipersensibilidad a los Alimentos/metabolismo , Metabolómica/métodos , Polen/química , Profilinas/química , Proteómica/métodos

RESUMEN

Bee pollen is consumed for its nutritional and pharmacological benefits, but it also contains hazardous allergens which have not been identified. Here, we identified two potential allergens, glutaredoxin and oleosin-B2, in Brassica napus bee pollen using mass spectrometry-based proteomics analyses, and used bioinformatics to predict their antigenic epitopes. Comparison of fermented (by Saccharomyces cerevisiae) and unfermented bee pollen samples indicated that glutaredoxin and oleosin-B2 contents were significantly decreased following fermentation, while the contents of their major constituent oligopeptides and amino acids were significantly increased based on metabolomics analyses. Immunoblot analysis indicated that the IgE-binding affinity with extracted bee pollen proteins was also significantly decreased after fermentation, suggesting a reduction in the allergenicity of fermented bee pollen. Furthermore, fermentation apparently promoted the biosynthesis of L-valine, L-isoleucine, L-tryptophan, and L-phenylalanine, as well as their precursors or intermediates. Thus, fermentation could potentially alleviate allergenicity, while also positively affecting nutritional properties of B. napus bee pollen. Our findings might provide a scientific foundation for improving the safety of bee pollen products to facilitate its wider application.

RESUMEN

MED20 is a non-essential subunit of the transcriptional coactivator Mediator complex, but its physiological function remains largely unknown. Here, we identify MED20 as a substrate of the anti-obesity CRL4-WDTC1 E3 ubiquitin ligase complex through affinity purification and candidate screening. Overexpression of WDTC1 leads to degradation of MED20, whereas depletion of WDTC1 or CUL4A/B causes accumulation of MED20. Depleting MED20 inhibits adipogenesis, and a non-degradable MED20 mutant restores adipogenesis in WDTC1-overexpressing cells. Furthermore, knockout of Med20 in preadipocytes abolishes development of brown adipose tissues. Removing one allele of Med20 in preadipocytes protects mice from diet-induced obesity and reverses weight gain in Cul4a- or Cul4b-depleted mice. Chromatin immunoprecipitation sequencing (ChIP-seq) analysis reveals that MED20 organizes the early adipogenic complex by bridging C/EBPß and RNA polymerase II to promote transcription of the central adipogenic factor, PPARγ. Our findings have thus uncovered a critical role of MED20 in promoting adipogenesis, development of adipose tissue and diet-induced obesity.

Asunto(s)

Adipogénesis , Tejido Adiposo Pardo , Dieta , Obesidad , Subunidades de Proteína , Animales , Humanos , Ratones , Células 3T3-L1 , Adipocitos/metabolismo , Tejido Adiposo Pardo/metabolismo , Alelos , Secuencia de Bases , Proteína beta Potenciadora de Unión a CCAAT/metabolismo , Elementos de Facilitación Genéticos/genética , Células HEK293 , Ratones Endogámicos C57BL , Obesidad/metabolismo , Obesidad/patología , PPAR gamma/genética , PPAR gamma/metabolismo , Subunidades de Proteína/metabolismo , Proteínas/metabolismo , Proteolisis , Receptores de Interleucina-17/metabolismo , ARN Polimerasa II/metabolismo , Especificidad por Sustrato , Transcripción Genética

RESUMEN

Radioresistance is a crucial factor for the failure of iodine 131 (131I)-based radiotherapy for differentiated thyroid carcinoma (DTC). This study aimed to explore the effect of circ_NEK6 on the development of 131I resistance in DTC and its potential mechanism. In this study, we demonstrated that circ_NEK6 expression was significantly elevated in 131I-resistant DTC tissues and cell lines. Knockdown of circ_NEK6 significantly repressed 131I resistance via inhibiting cell proliferation, migration, invasion abilities, and inducing cell apoptosis and DNA damage in 131I-resistant DTC cells. Mechanistically, knockdown of circ_NEK6 suppressed 131I resistance in DTC by upregulating the inhibitory effect of miR-370-3p on the expression of myosin heavy chain 9 (MYH9). In vivo experiments showed that circ_NEK6 inhibition aggravated 131I radiation-induced inhibition of xenograft tumor growth. Taken together, knockdown of circ_NEK6 repressed 131I resistance in DTC cells by regulating the miR-370-3p/MYH9 axis, indicating that circ_NEK6 may act as a potential biomarker and therapeutic target for DTC patients with 131I resistance.

Asunto(s)

Carcinoma/genética , Carcinoma/radioterapia , ARN Circular/genética , Tolerancia a Radiación/genética , Neoplasias de la Tiroides/genética , Neoplasias de la Tiroides/radioterapia , Animales , Apoptosis/genética , Carcinoma/metabolismo , Línea Celular Tumoral , Movimiento Celular/genética , Proliferación Celular/genética , Supervivencia Celular/efectos de la radiación , Femenino , Técnicas de Silenciamiento del Gen , Humanos , Radioisótopos de Yodo/uso terapéutico , Ratones , MicroARNs/genética , MicroARNs/metabolismo , Cadenas Pesadas de Miosina/genética , Cadenas Pesadas de Miosina/metabolismo , Quinasas Relacionadas con NIMA/genética , Quinasas Relacionadas con NIMA/metabolismo , Invasividad Neoplásica/genética , Trasplante de Neoplasias , ARN Circular/metabolismo , Neoplasias de la Tiroides/metabolismo

RESUMEN

In hippocampal pyramidal cells, a small subset of dendritic spines contain endoplasmic reticulum (ER). In large spines, ER frequently forms a spine apparatus, while smaller spines contain just a single tubule of smooth ER. Here we show that the ER visits dendritic spines in a non-random manner, targeting spines during periods of high synaptic activity. When we blocked ER motility using a dominant negative approach against myosin V, spine synapses became stronger compared to controls. We were not able to further potentiate these maxed-out synapses, but long-term depression (LTD) was readily induced by low-frequency stimulation. We conclude that the brief ER visits to active spines have the important function of preventing runaway potentiation of individual spine synapses, keeping most of them at an intermediate strength level from which both long-term potentiation (LTP) and LTD are possible.

Asunto(s)

Espinas Dendríticas/metabolismo , Retículo Endoplásmico/metabolismo , Sinapsis/metabolismo , Animales , Hipocampo/metabolismo , Potenciación a Largo Plazo , Miosina Tipo V/metabolismo , Ratas Wistar , Imagen de Lapso de Tiempo

RESUMEN

In this study, for the first time, the integration of nontoxic ternary copper halide Cs3Cu2I5 with one-dimensional Si nanowires (NWs) was reported to achieve an ultraviolet (UV)-enhanced Si NW broadband photodetector. A compact and uniform coverage of Cs3Cu2I5 on the top and sidewall of Si NWs formed a core/shell heterostructure, in which Si NWs served as the growth template and the electron-transport layer, and Cs3Cu2I5 was employed as the UV photoactive material and the hole-transport layer. The as-fabricated Cs3Cu2I5/Si-core/shell NW photodetector demonstrates a multiband photodetection from the deep UV to near-infrared region, a fast response speed of 92.5/189.2 µs (265 nm), and a high photoresponsivity of 130 mA/W, nearly 600 times as much as the reference device constructed using Si NWs. More importantly, the proposed photodetector exhibits an excellent stability in air ambient. Typically, it could endure a high temperature of 60 °C for 11 h consecutive working; after storage in air ambient for two weeks, its photodetection ability can almost be retained. Additionally, high-resolution UV imaging applications were presented by employing the proposed photodetector as sensing pixels. These obtained results verify the effectiveness of the Cs3Cu2I5/Si-core/shell NW heterojunction strategy for UV-enhanced broadband photodetection, making such a device really possible for practical applications.

RESUMEN

A vast amount of evidence indicates that long non-coding RNAs (lncRNAs) are involved in cancer. Previous studies have indicated that lncRNA DiGeorge syndrome critical region gene 5 (DGCR5) is aberrantly expressed in lung cancer, pancreatic ductal adenocarcinoma and hepatocellular carcinoma. However, the role of DGCR5 in papillary thyroid carcinoma (PTC) has remained elusive. In the present study, it was revealed that DGCR5 was significantly downregulated in PTC tissues compared with that in adjacent normal tissues. Through functional experiments, it was demonstrated that ectopic overexpression of DGCR5 markedly suppressed PTC cell growth and invasion. A bioinformatics analysis suggested that DGCR5 binds to microRNA (miR)-2861. A total of 5 putative binding sites for miR-2861 were identified in DGCR5, and a luciferase reporter assay confirmed the direct interaction between DGCR5 and miR-2861. Furthermore, reverse transcription-quantitative polymerase chain reaction analysis indicated that ectopic overexpression of DGCR5 led to a decreased expression of miR-2861 in PTC cells and miR-2861 mimic transfection caused a downregulation of DGCR5. miR-2861 level was upregulated in PTC tissues compared with adjacent tissues and negatively correlated with DGCR5 level. In addition, rescue experiments indicated that ectopic expression of miR-2861 reversed the effects of DGCR5 overexpression on PTC cell proliferation and invasion. Taken together, the present results demonstrated that DGCR5 inhibits PTC progression via sponging miR-2861, indicating DGCR5 may serve as a therapeutic target.

RESUMEN

Thyroid carcinoma is primarily treated by surgery combined with radioactive 131iodine (131I) treatment; however, certain patients exhibit resistance to 131I treatment. Previous research indicated that nuclear factor­κB (NF­κB) was associated with resistance to 131I in cancer cells. The present study aimed to investigate the effects of NF­κB on 131I uptake and apoptosis in thyroid carcinoma cells. TPC­1 and BCPAP cell lines were employed as research models in the present study, and the expression of NF­κB was inhibited by RNA interference (RNAi). The ability of TPC­1 and BCPAP cells to uptake 131I was measured and the cell viability was detected by an MTT assay. Finally, the expression of the apoptosis­associated proteins X­linked inhibitor of apoptosis (XIAP), cellular inhibitor of apoptosis protein 1 (cIAP1) and caspase­3 in TCP­1 and BCPAP cells was determined by western blotting. Western blotting results demonstrated that the expression levels of NF­κB in TPC­1 and BCPAP cells were successfully downregulated by RNAi (P<0.05), while analysis of 131I uptake revealed no significant alterations in the 131I uptake ability of cells following RNAi (P>0.05). MTT experiments demonstrated that the inhibition of NF­κB expression in combination with radiation (131I treatment) led to a marked reduction in cell viability (P<0.05). Furthermore, western blot analysis revealed that the inhibition of NF­κB expression downregulated the expression levels of XIAP and cIAP1 (P<0.05), while the expression levels of caspase­3 were upregulated, indicating that the observed reduction in cell viability following NF­κB inhibition may be due to an increased level of apoptosis. Although NF­κB inhibition did not affect the 131I uptake of thyroid cancer cells, this inhibition may increase the apoptotic effects of radioactive 131I.

Asunto(s)

Apoptosis , Radioisótopos de Yodo/metabolismo , FN-kappa B/metabolismo , Neoplasias de la Tiroides/metabolismo , Proteínas Reguladoras de la Apoptosis/metabolismo , Línea Celular Tumoral , Supervivencia Celular , Expresión Génica , Humanos , FN-kappa B/genética , Interferencia de ARN , Neoplasias de la Tiroides/genética , Neoplasias de la Tiroides/patología

RESUMEN

The aim of this study was to evaluate the immune responses in turbot, Scophthalmus maximus, treated with 1 × 107 cfu/ml attenuated Edwardsiella tarda (0.1 ml/fish) under low density (LD; ∼5.25-5.13 kg/m2, initial to final density), medium density (MD; ∼10.41-13.95 kg/m2), and high density (HD; ∼20.53-30.77 kg/m2) conditions for 8 weeks. The results showed that there was a peak value in the percentage of sIg+ (surface immunoglobulin-positive) cells in blood leucocytes (BL), spleen leucocytes (SL), and pronephros leucocytes (PL) during the sixth week in the HD, which was delayed by week compared with the other groups. The specific immunoglobulin M (IgM) antibody levels increased from the first week in all groups and reached a peak in the fifth week in the LD and MD groups, but in the sixth week in the HD group. The serum cortisol levels were greater in the HD group compared with the other groups in the last 3 or 4 weeks. These results show that stocking turbot at a LD obtained the most effective immunization, and thus we conclude that crowding stress may reduce the ability to deal with immune challenge.

Asunto(s)

Vacunas Bacterianas/inmunología , Aglomeración , Edwardsiella tarda/inmunología , Peces Planos/inmunología , Inmunidad Innata , Animales , Distribución Aleatoria , Estrés Fisiológico/inmunología , Vacunación/veterinaria , Vacunas Atenuadas/inmunología

RESUMEN

Nitrite (NO2(-)) is commonly present as contaminant in aquatic environment and toxic to aquatic organisms. In the present study, we investigated the effects of nitrite exposure on haematological parameters, oxidative stress and apoptosis in juvenile turbot (Scophthalmus maximus). Fish were exposed to various concentrations of nitrite (0, 0.02, 0.08, 0.4 and 0.8mM) for 96 h. Fish blood and gills were collected to assay haematological parameters, oxidative stress and expression of genes after 0, 24, 48 and 96 h of exposure. In blood, the data showed that the levels of methemoglobin (MetHb), triglyceride (TG), potassium (K(+)), cortisol, heat shock protein 70 (HSP70) and glucose significantly increased in treatments with higher concentrations of nitrite (0.4 and/or 0.8mM) after 48 and 96 h, while the levels of haemoglobin (Hb) and sodium (Na(+)) significantly decreased in these treatments. In gills, nitrite (0.4 and/or 0.8mM) apparently reduced the levels of superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) and glutathione (GSH), increased the formation of malondialdehyde (MDA), up-regulated the mRNA levels of c-jun amino-terminal kinase (JUK1), p53, caspase-3, caspase-7 and caspase-9 after 48 and 96 h of exposure. The results suggested caspase-dependent and JUK signaling pathways played important roles in nitrite-induced apoptosis in fish. Further, this study provides new insights into how nitrite affects the physiological responses and apoptosis in a marine fish.

Asunto(s)

Apoptosis/efectos de los fármacos , Peces Planos/sangre , Nitritos/toxicidad , Estrés Oxidativo/efectos de los fármacos , Contaminantes Químicos del Agua/toxicidad , Animales , Caspasa 3/metabolismo , Caspasa 9/metabolismo , Catalasa/metabolismo , Peces Planos/crecimiento & desarrollo , Peces Planos/metabolismo , Branquias/efectos de los fármacos , Branquias/metabolismo , Branquias/patología , Glutatión/metabolismo , Glutatión Peroxidasa/metabolismo , Malondialdehído/metabolismo , Superóxido Dismutasa/metabolismo

RESUMEN

Neocortical neurons with similar functional properties assemble into spatially coherent circuits, but it remains unclear how inhibitory interneurons are organized. We applied in vivo two-photon functional Ca(2+) imaging and whole-cell recording of synaptic currents to record visual responses of cortical neurons and analyzed their spatial arrangements. GABAergic interneurons were clustered in the 3D space of the mouse visual cortex, and excitatory neurons located within the clusters (insiders) had a lower amplitude and sharper orientation tuning of visual responses than outsiders. Inhibitory synaptic currents recorded from the insiders were larger than those of the outsiders. Single, isolated interneurons did not show such a location-tuning/amplitude relationship. The two principal subtypes of interneurons, parvalbumin- and somatostatin-expressing neurons, also formed clusters with only slightly overlapping each other and exhibited a different location-tuning relationship. These findings suggest that GABAergic interneurons and their subgroups form clusters to make their inhibitory function more effective than isolated interneurons.

Asunto(s)

Neuronas GABAérgicas/fisiología , Corteza Visual/citología , Animales , Señalización del Calcio , Femenino , Imagenología Tridimensional , Interneuronas/fisiología , Masculino , Potenciales de la Membrana , Ratones Transgénicos , Estimulación Luminosa , Percepción Visual

RESUMEN

Lead pollution is a very serious problem in China with the rapid economic development. A large amount of lead has been released into the environment due to mineral processing activities and has impacted water resources, soils, vegetables, and crops. The gasoline with lead has been banned in China since July 1, 2000. Though a noticeable decrease of lead poisoning rates has been evidenced, the children's blood lead levels are still significantly higher than those in developed countries. Therefore, lowering the lead exposure in childhood continues to be an important public health objective in China. There is also a lot that remains to be done to reduce children's exposure to lead. In this section, five scientists from China presented latest research results regarding the current situation of lead poisoning in China, the mechanisms involved in lead-induced neurotoxicity, and the new advances related to the potential therapy methods. Their researches may pave new way not only for the prevention of lead poisoning but also for the treatment of affected children in China and other countries.

Asunto(s)

Desarrollo Infantil/efectos de los fármacos , Exposición a Riesgos Ambientales/efectos adversos , Contaminantes Ambientales/efectos adversos , Intoxicación del Sistema Nervioso por Plomo en la Infancia/etiología , Plomo/efectos adversos , Sistema Nervioso/efectos de los fármacos , Factores de Edad , Animales , Pueblo Asiatico , Barrera Hematoencefálica/efectos de los fármacos , Barrera Hematoencefálica/metabolismo , Barrera Hematoencefálica/fisiopatología , Niño , China/epidemiología , Modelos Animales de Enfermedad , Humanos , Intoxicación del Sistema Nervioso por Plomo en la Infancia/etnología , Intoxicación del Sistema Nervioso por Plomo en la Infancia/metabolismo , Intoxicación del Sistema Nervioso por Plomo en la Infancia/fisiopatología , Sistema Nervioso/crecimiento & desarrollo , Sistema Nervioso/metabolismo , Sistema Nervioso/fisiopatología , Neuroglía/efectos de los fármacos , Neuroglía/metabolismo , Plasticidad Neuronal/efectos de los fármacos , Ratas , Medición de Riesgo , Factores de Riesgo , Transmisión Sináptica/efectos de los fármacos , Factores de Tiempo

RESUMEN

With the increasing applications of titanium dioxide nanoparticles (TiO(2) NPs) in industry and daily life, an increasing number of studies showed that TiO(2) NPs may have negative effects on the respiratory or metabolic circle systems of organisms, while very few studies focused on the brain central nervous system (CNS). Synaptic plasticity in hippocampus is believed to be associated with certain high functions of CNS, such as learning and memory. Thus, in this study, we investigated the effects of developmental exposure to TiO(2) NPs on synaptic plasticity in rats' hippocampal dentate gyrus (DG) area using in vivo electrophysiological recordings. The input/output (I/O) functions, paired-pulse reaction (PPR), field excitatory postsynaptic potential, and population spike amplitude were measured. The results showed that the I/O functions, PPR, and long-term potentiation were all attenuated in lactation TiO(2) NPs-exposed offspring rats compared with those in the control group. However, in the pregnancy TiO(2) NPs exposure group, only PPR was attenuated significantly. These findings suggest that developmental exposure to TiO(2) NPs could affect synaptic plasticity in offspring's hippocampal DG area in vivo, which indicates that developmental brains, especially in lactation, are susceptible to TiO(2) NPs exposure. This study reveals the potential toxicity of TiO(2) NPs in CNS. It may give some hints on the security of TiO(2) NPs production and application and shed light on its future toxicological studies.

Asunto(s)

Anestesia , Giro Dentado/efectos de los fármacos , Hipocampo/efectos de los fármacos , Exposición Materna , Nanopartículas del Metal , Plasticidad Neuronal/efectos de los fármacos , Titanio/farmacología , Potenciales de Acción , Animales , Giro Dentado/fisiología , Femenino , Hipocampo/fisiología , Potenciación a Largo Plazo/efectos de los fármacos , Microscopía Electrónica de Transmisión , Embarazo , Ratas , Ratas Sprague-Dawley

RESUMEN

Epigallocatechin-3-gallate (EGCG), a catechin polyphenols component, is the main ingredient of green tea extract. It has been reported that EGCG is a potent antioxidant and beneficial in oxidative stress-related diseases, but others and our previous study showed that EGCG has pro-oxidant effects at high concentration. Thus, in this study, we tried to examine the possible pathway of EGCG-induced cell death in cultures of rat hippocampal neurons. Our results showed that EGCG caused a rapid elevation of intracellular free calcium levels ([Ca(2+)](i)) in a dose-dependent way. Exposure to EGCG dose- and time-dependently increased the production of reactive oxygen species (ROS) and reduced mitochondrial membrane potential (Deltapsi(m)) as well as the Bcl-2/Bax expression ratio. Importantly, acetoxymethyl ester of 5,5'-dimethyl-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid, ethylene glycol-bis-(2-aminoethyl)-N,N,N',N'-tetraacetic acid, and vitamin E could attenuate EGCG-induced apoptotic responses, including ROS generation, mitochondrial dysfunction, and finally partially prevented EGCG-induced cell death. Furthermore, treatment of hippocampal neurons with EGCG resulted in an elevation of caspase-3 and caspase-9 activities with no significant accompaniment of lactate dehydrogenase release, which provided further evidence that apoptosis was the dominant mode of EGCG-induced cell death in cultures of hippocampal neurons. Taken together, these findings indicated that EGCG induced hippocampal neuron death through the mitochondrion-dependent pathway.

Asunto(s)

Calcio/metabolismo , Catequina/análogos & derivados , Hipocampo/metabolismo , Neuronas/metabolismo , Estrés Oxidativo/fisiología , Animales , Catequina/farmacología , Muerte Celular/efectos de los fármacos , Muerte Celular/fisiología , Células Cultivadas , Relación Dosis-Respuesta a Droga , Hipocampo/efectos de los fármacos , Potenciales de la Membrana/efectos de los fármacos , Potenciales de la Membrana/fisiología , Neuronas/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Ratas , Ratas Wistar , Transducción de Señal/efectos de los fármacos , Transducción de Señal/fisiología

RESUMEN

(-)-Epigallocatechin-3-gallate (EGCG), the main active component of green tea, is commonly known for its beneficial properties at low doses. On the other hand, little is known about the adverse effects of EGCG. Voltage-gated sodium channel (VGSC) is responsible for both initiation and propagation of action potentials of the neurons in the hippocampus and throughout the central nervous system (CNS). In this study, the effects of EGCG on voltage-gated sodium channel currents (I(Na)) were investigated in rat primary cultures of hippocampal CA1 neurons via the conventional whole-cell patch-clamp technique. We found that I(Na) was not affected by EGCG at the concentration of 0.1microM, but was completely blocked by EGCG at the concentration of 400microM and higher, and EGCG reduced the amplitudes of I(Na) in a concentration-dependent manner in the range of 0.1-400microM. Furthermore, our results also showed that at the concentration of 100microM, EGCG was known to have the following performances: (1) it decreased the activation threshold and the voltage at which the maximum I(Na) current was evoked, caused negative shifts of I(Na) steady-state activation curve. (2) It enlarged I(Na) tail-currents. (3) It induced a left shift of the steady-state inactivation. (4) It reduced fraction of available sodium channels. (5) It delayed the activation of I(Na) in a voltage-dependent manner. (6) It prolonged the time course of the fast inactivation of sodium channels. (7) It accelerated the activity-dependent attenuation of I(Na). On the basis of these findings, we propose that EGCG could impair certain physiological functions of VGSCs, which may contribute, directly or indirectly, to EGCG's effects in CNS.

Asunto(s)

Catequina/análogos & derivados , Hipocampo/citología , Neuronas/metabolismo , Agonistas de los Canales de Sodio , Animales , Animales Recién Nacidos , Catequina/farmacología , Células Cultivadas , Interpretación Estadística de Datos , Relación Dosis-Respuesta a Droga , Electrofisiología , Hipocampo/efectos de los fármacos , Activación del Canal Iónico/efectos de los fármacos , Neuronas/efectos de los fármacos , Técnicas de Placa-Clamp , Ratas , Bloqueadores de los Canales de Sodio/farmacología , Canales de Sodio/metabolismo

RESUMEN

BACKGROUND: The growing applications of nanotechnologic products, such as quantum dots (QDs), increase the likelihood of exposure. Furthermore, their accumulation in the bioenvironment and retention in cells and tissues are arousing increasing worries about the potentially harmful side effects of these nanotechnologic products. Previous studies concerning QD cytotoxicity focused on the reactive oxygen species produced by QDs. Cellular calcium homeostasis dysregulation caused by QDs may be also responsible for QD cytotoxicity. Meanwhile the interference of QDs with voltage-gated sodium channel (VGSC) current (I(Na)) may lead to changes in electrical activity and worsen neurotoxicologic damage. OBJECTIVE: We aimed to investigate the potential for neurotoxicity of cadmium selenium QDs in a hippocampal neuronal culture model, focusing on cytoplasmic calcium levels and VGSCs function. METHODS: We used confocal laser scanning and standard whole-cell patch clamp techniques. RESULTS: We found that a) QDs induced neuron death dose dependently; b) cytoplasmic calcium levels were elevated for an extended period by QD treatment, which was due to both extracellular calcium influx and internal calcium release from endoplasmic reticulum; and c) QD treatment enhanced activation and inactivation of I(Na), prolonged the time course of activation, slowed I(Na) recovery, and reduced the fraction of available VGSCs. CONCLUSION: Results in this study provide new insights into QD toxicology and reveal potential risks of their future applications in biology and medicine.

Asunto(s)

Compuestos de Cadmio/toxicidad , Calcio/metabolismo , Hipocampo/citología , Neuronas/efectos de los fármacos , Puntos Cuánticos , Compuestos de Selenio/toxicidad , Canales de Sodio/metabolismo , Animales , Muerte Celular/efectos de los fármacos , Células Cultivadas , Citoplasma/metabolismo , Relación Dosis-Respuesta a Droga , Neuronas/citología , Neuronas/metabolismo , Ratas

RESUMEN

Recent studies have shown that lead (Pb) could disrupt the prooxidant/antioxidant balance of tissue which leads to biochemical and physiological dysfunction. Epigallocatechin-3-gallate (EGCG), a catechin polyphenols component, is found to be an effective antioxidant. The present study investigated whether EGCG administration could reverse the changes on redox states in rat hippocampus caused by lead exposure. The association between redox status changes and long-term potentiation (LTP) in CA1 area of hippocampus were also examined. Wistar rats exposed to lead from postnatal day 1 were followed by 10 days of EGCG (10, 25 and 50 mg/kg) administration through intraperitoneally (ip), and the rats were sacrificed for experiments at the age of 21-23 days. The experimental results showed that glutathione (GSH) and superoxide dismutase (SOD) activity decreased accompanied with LTP amplitude decrease in CA1 area of hippocampus in the lead-exposed group. EGCG supplementation following lead intoxication resulted in increases in the GSH and SOD levels and increases in the LTP amplitude. Malondialdehyde (MDA) levels, a major lipid peroxidation byproduct, increased following lead exposure and decreased following EGCG treatment. In hippocampal neuron culture model, lead exposure (20 microM) significantly inhibited the viability of neurons which was followed by an accumulation of ROS and a decrease of mitochondrial membrane potential (delta Psi m). Treatment by EGCG (10-50 microM) effectively increased cell viability, decreased ROS formation and improved delta Psi m in hippocampal neurons exposed to lead. These observations suggest that EGCG is a potential complementary agent in the treatment of chronic lead intoxication through its antioxidative character.

Asunto(s)

Antioxidantes/farmacología , Catequina/análogos & derivados , Hipocampo/efectos de los fármacos , Compuestos Organometálicos/toxicidad , Estrés Oxidativo/efectos de los fármacos , Animales , Animales Recién Nacidos , Catequina/farmacología , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Relación Dosis-Respuesta a Droga , Antagonismo de Drogas , Femenino , Glutatión/metabolismo , Hipocampo/metabolismo , Hipocampo/fisiopatología , Inyecciones Intraperitoneales , Lactancia , Peroxidación de Lípido/efectos de los fármacos , Potenciación a Largo Plazo/efectos de los fármacos , Malondialdehído/metabolismo , Exposición Materna , Potencial de la Membrana Mitocondrial/efectos de los fármacos , Neuronas/efectos de los fármacos , Neuronas/metabolismo , Ratas , Ratas Wistar , Especies Reactivas de Oxígeno/metabolismo , Superóxido Dismutasa/metabolismo