RESUMEN
MicroRNAs that modulate transcription can regulate other microRNAs and are also up-regulated under pathological stress. MicroRNA-499 (miR-499), microRNA-208a (miR-208a) and B-cell lymphoma 2 (Bcl-2) play roles in cardiovascular diseases, such as direct reprogramming of cardiac fibroblast into cardiomyocyte and cardiomyocyte apoptosis. Whether miR208a, miR499 and Bcl-2 were critical regulators in cardiac fibroblast apoptosis under mechanical stretching conditions in human cardiac fibroblasts-adult atrial (HCF-aa) was investigated. Using negative pressure, HCF-aa grown on a flexible membrane base were cyclically stretched to 20% of their maximum elongation. In adult rats, an aortocaval shunt was used to create an in vivo model of volume overload. MiR208a was up-regulated early by stretching and returned to normal levels with longer stretching cycles, whereas the expression of miR499 and Bcl-2 was up-regulated by longer stretching times. Pre-treatment with antagomir-499 reversed the miR-208a down-regulation, whereas Bcl-2 expression could be suppressed by miR-208a overexpression. In the HCF-aa under stretching for 1 h, miR-499 overexpression decreased pri-miR-208a luciferase activity; this inhibition of pri-miR-208a luciferase activity with stretching was reversed when the miR-499-5p binding site in pri-miR-208a was mutated. The addition of antagomir-208a reversed the Bcl-2-3'UTR suppression from stretching for 1 h. Flow cytometric analysis revealed that pre-treatment with miR-499 or antagomir-208a inhibited cellular apoptosis in stretched HCF-aa. In hearts with volume overload, miR-499 overexpression inhibited myocardial miR-208a expression, whereas Bcl-2 expression could be suppressed by the addition of miR-208a. In conclusion, miR-208a mediated the regulation of miR-499 on Bcl-2 expression in stretched HCF-aa and hearts with volume overload.
Asunto(s)
Fibroblastos/metabolismo , Atrios Cardíacos/citología , MicroARNs/genética , Ejercicios de Estiramiento Muscular , Regiones no Traducidas 3' , Animales , Apoptosis/genética , Biomarcadores , Regulación de la Expresión Génica , Humanos , Miocardio/metabolismo , Proteínas Proto-Oncogénicas c-bcl-2/genética , Interferencia de ARN , RatasRESUMEN
Visfatin is an adipocytokine with important roles in endothelial angiogenesis. Hyperbaric oxygen (HBO) has been widely used to treat various medical illness with enhanced angiogenesis. The molecular effects of HBO on visfatin under hypoxia are poorly understood. This study aimed to investigate the effect of HBO on visfatin in hypoxic human coronary arterial endothelial cells (HCAECs). HCAECs under chemical hypoxia (antimycin A, 0.01 mmol/L) were exposed to HBO (2.5 atmosphere absolute; ATA) for 2-4 hours. Western blot, real-time polymerase chain reaction, electrophoretic mobility shift assay, luciferase promoter activity, migration and tube formation assay, and in vitro glucose uptake were measured. Visfatin protein expression increased in hypoxic HCAECs with earlier angiotensin II (AngII) secretion and c-Jun N-terminal kinase (JNK) phosphorylation, which could be effectively suppressed by the JNK inhibitor (SP600125), AngII antibody or AngII receptor blocker (losartan). In hypoxic HCAECs, HBO further induced earlier expression of visfatin and AngII. Hypoxia significantly increased DNA-protein binding activity of hypoxia-inducible factor-1α (HIF-1α) and visfatin. Hypoxia, hypoxia with HBO and exogenous addition of AngII also increased promoter transcription to visfatin; SP600125 and losartan blocked this activity. In HCAECs, glucose uptake, migration and tube formation were increased in the presence of hypoxia with HBO, but were inhibited by visfatin small interfering RNA, SP600125 and losartan. In conclusion, HBO activates visfatin expression and angiogenesis in hypoxic HCAECs, an effect mediated by AngII, mainly through the JNK pathway.
Asunto(s)
Angiotensina II/metabolismo , Vasos Coronarios/metabolismo , Citocinas/metabolismo , Células Endoteliales/metabolismo , Proteínas Quinasas JNK Activadas por Mitógenos/metabolismo , Neovascularización Patológica/metabolismo , Nicotinamida Fosforribosiltransferasa/metabolismo , Oxígeno/metabolismo , Antracenos/farmacología , Movimiento Celular/efectos de los fármacos , Movimiento Celular/genética , Células Cultivadas , Vasos Coronarios/efectos de los fármacos , Células Endoteliales/efectos de los fármacos , Glucosa/metabolismo , Humanos , Oxigenoterapia Hiperbárica/métodos , Hipoxia/metabolismo , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Losartán/farmacología , Regiones Promotoras Genéticas/efectos de los fármacos , Regiones Promotoras Genéticas/genética , ARN Interferente Pequeño/genética , Transducción de Señal/efectos de los fármacos , Transducción de Señal/fisiologíaRESUMEN
Energy barriers for flipping the transverse dipole moments in poly(vinylidene fluoride) (PVDF) and related copolymers and terpolymers are predicted using the nudged elastic band method. The dipole moments flip individually along the chain, with an order and energy barrier magnitudes (0.1-1.2 eV) that depend on the chain composition and environment. Trifluoroethylene (TrFE) and chlorofluoroethylene (CFE) monomers have larger energy barriers than VDF monomers, while a chain in an amorphous environment has a similar transition pathway as that of an isolated molecule. In a crystalline environment, TrFE and CFE monomers expand the lattice and lower the energy barriers for flipping VDF monomers. This finding is consistent with experimental observations of a large electrocaloric effect in P(VDF-TrFE-CFE) terpolymers.