p66shc-mediated toxicity of high-dose alfa-tocopherol in renal proximal tubule cells

α-Tocopherol (TOC) is a widely used supplement known for its role as an antioxidant. Previously, we have shown that TOC elicits adaptive responses by upregulating the ERK/CREB/HO-1 pathway, which depends on its concentration in cultured renal proximal tubule cells (RPTCs). This suggests that high-dose TOC (hTOC) may elicit adverse effects via inflicting oxidative stress. Since the pro-oxidant p66shc is a major mediator of oxidant injury in various models of renal toxicants, we tested the hypothesis that hTOC elicits renal toxicity through activation of p66shc and consequent oxidative stress. RPTCs (NRK52E) were treated with high-dose TOC (hTOC; 400 nM) in cells where expression or mitochondrial cytochrome c-binding of p66shc was manipulated by genetic means. Intracellular production of reactive oxygen species (ROS), mitochondrial depolarization, and cell viability was also determined. Additionally, activation of the pro-survival ERK/CREB/HO-1 signaling and the p66shc promoter was determined via reporter luciferase assays. hTOC decreased cell viability via increasing ROS-dependent mitochondrial depolarization and suppressing the pro-survival ERK/CREB/HO-1 pathway via transcriptional activation of p66shc. Conversely, either knockdown of p66shc, mutation of its mitochondrial cytochrome c-binding site, or overexpression of ERK or HO-1 ameliorated adverse effects of hTOC and restored the pro-survival signaling. The pro-oxidant p66shc plays dual role in toxicity of high-dose TOC: it provokes oxidative stress and suppresses adaptive responses (AU)

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Melatonin attenuated adipogenesis through reduction of the CCAAT/enhancer binding protein beta by regulating the glycogen synthase 3 beta in human mesenchymal stem cells

Adipogenic differentiation is characterized by an increase in two major transcription factors: peroxisome proliferator-activated receptor gamma (PPARγ) and the CCAAT/enhancer binding protein alpha (C/EBPα). These two signals are influenced by C/EBPβ and C/EBPδ and cross-regulate each other’s expression during the initial stages of adipogenesis. Melatonin has been known to act as not only a direct scavenger of free radicals but also an inhibitor of glycogen synthase kinase 3β (GSK-3β). Here, we report that melatonin inhibits the adipogenic differentiation of human mesenchymal stem cells (hMSCs) which is due to the regulations of C/EBPβ in the early stage of adipogenic differentiation. Melatonin reduced the lipid accumulation, adiponectin, and lipoprotein lipase (LPL) during the adipogenic differentiation of hMSCs. Since C/EBPβ has been associated with the activation of PPARγ and the consensus site of ERK/GSK-3β, PPARγ and β-catenin were detected by immunofluorescence staining after pretreatment of melatonin. Melatonin blocked the activation of PPARγ which induced the degradation of β-catenin. Melatonin also decreased the levels of cyclic adenosine-3,5-monophosphate (cAMP) and reactive oxygen species (ROS). The cAMP triggered the activity of C/EBPβ which is a critical inducer of PPARγ and C/EBPα activation in the early stage of adipogenic differentiation, and this is further affected by ROS production. The adipogenic marker proteins such as PPARγ, C/EBPα, C/EBPβ, and pERK were also decreased by melatonin. In summary, melatonin inhibited the cAMP synthesis through ROS reduction and the phosphorylation of the ERK/GSK-3β site which is known to be responsible for C/EBPβ activation for adipogenic differentiation in hMSCs (AU)

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Discordancia genotipo-fenotipo en un paciente con distrofia muscular de Duchenne por una nueva mutación: hipótesis de la función de amortiguación de la distrofina / Genotype-phenotype discordance in a Duchenne muscular dystrophy patient due to a novel mutation: insights into the shock absorber function of dystrophin

Introducción. La distrofia muscular de Duchenne (DMD) es un trastorno caracterizado por atrofia muscular progresiva y debilidad, debido a la ausencia o alteración de la función de la distrofina, una proteína que protege a las células del músculo de la tensión mecánica inducida durante la contracción. Las mutaciones en el gen DMD pueden dar lugar a diferentes fenotipos clínicos, conocidos colectivamente como distrofinopatías, de los cuales la DMD es el más grave. Caso clínico. Se presenta una deleción nueva de los exones 24-41, que no interrumpe el marco de lectura y se espera que origine un fenotipo leve. Por el contrario, el paciente tiene un fenotipo DMD grave. Conclusiones. Nuestra comunicación apoya la hipótesis de que la interrupción del sitio de unión a gamma-actina situado en el dominio cilíndrico central desempeña un papel crucial en la función de amortiguador de distrofina en las células musculares. La descripción de las variantes patogénicas en el gen DMD y los fenotipos resultantes tienen importantes implicaciones en el diseño de estrategias terapéuticas moleculares para la DMD (AU)

Introduction. Duchenne muscular dystrophy (DMD) is a genomic disorder characterized by progressive muscle wasting and weakness due to the absence or abnormal function of dystrophin; a protein that protects muscle cells from mechanical induced stress during contraction. Mutations in the DMD gene, may lead to different clinical phenotypes, collectively known as dystrophinopathies, of which DMD has the earliest onset and most severe progression. Case report. We report a novel deletion of exons 24-41, predicted to maintain the reading frame and expected to result in a mild phenotype. Conversely, the patient has a severe DMD phenotype. Conclusions. Our report supports the hypothesis that disruption of the gamma-actin-binding site located in the central rod domain plays a crucial role in the shock absorber function of dystrophin in muscle cells. Description of pathogenic variants in the DMD gene and the resulting phenotypes has important implications on the designing of molecular therapeutic approaches for DMD (AU)

Características químicas, mecanismo de acción y actividad antiviral de etravirina / Chemical characteristics, mechanism of action and antiviral activity of etravirine

Etravirina (ETR) es un derivado diarilpirimidínico. Se trata de una molécula policíclica, constituida por 3 anillos aromáticos unidos por enlaces sencillos (C20H15BrN60). Ejerce su acción mediante un mecanismo de inhibición no competitiva, al unirse a un bolsillo hidrofóbico (binding pocket), muy cercano al centro activo de la enzima, provocando un cambio alostérico hacia una conformación que distorsiona su estructura e impide la polimerización del ADN. Al tratarse de 3 anillos unidos por enlaces sencillos, la molécula está dotada de una enorme flexibilidad y capacidad de torsión. Debido a estas características, ETR puede "acomodarse" a cambios conformacionales en el binding pocket, incluidas un gran número de las conformaciones provocadas por las mutaciones de resistencia que aparecen tras el fracaso a regímenes que incluyen efavirenz o nevirapina. Esta particular estructura química explicará gran parte de sus peculiaridades y diferencias en cuanto a su potencia antiviral y su elevada barrera genética. ETR es una molécula muy activa frente a VIH-1. Presenta una elevada barrera genética y ha demostrado actividad antiviral frente a un amplio panel de virus recombinantes que incorporan mutaciones de resistencia a los no análogos de primera generación. De igual modo, ha demostrado ser eficaz frente a diversos subtipos del grupo M del virus de la inmunodeficiencia humana (VIH) 1 (A, B, C, D, F y H y formas recombinantes CRF01_AE, CRF02_AG, CRF05_ DF) y frente a aislados de VIH-1 grupo O. ETR, como el resto de no análogos, no ha demostrado actividad antiviral frente a VIH-2

Etravirine (ETR) is a diarylpyrimidine derivative with a polycyclic molecule composed of 3 aromatic rings with single bonds between the rings (C20H15BrN60). The drug acts through a mechanism of noncompetitive inhibition on binding to a hydrophobic binding pocket, very close to the active center of the enzyme, provoking an allosteric transition to a conformation that distorts its structure and impedes DNA polymerization. The 3 rings with single bonds between the rings confer the molecule with great flexibility and torsion. Because of these characteristics, etravirine can adapt to conformational changes in the binding pocket, including a large number of the conformations provoked by the resistance mutations that appear after failure to regimens that include efavirenz or nevirapine. This specific chemical structure largely explains the drug's distinguishing features in terms of its antiviral potency and high genetic barrier. ETR is a highly active molecule against HIV-1. This drug has a high genetic barrier to resistance and has demonstrated antiviral activity against a wide panel of recombinant viruses that incorporate resistance mutations to first-generation non-nucleoside analogues. Equally, ETR has demonstrated efficacy against several subtypes of the M group of HIV-1 (A, B, C, D, F and H, and recombinant forms CRF01_AE, CRF02_AG, CRF05_DF), as well as against isolates of HIV-1 group O. ETR, as the rest of non-nucleoside analogues, does not have demonstrated antiviral activity against HIV-2

Regulation of lypolysis in white adipose tissuesof lean and obese Zucker rats

Obese Zucker rat is often used as a model of genetic obesity to understand themechanism of the development of obesity. In the present work, in order to betterunderstand the regulation of lipolysis in the Zucker rat, the lipolytic activities ofadipocytes isolated from different adipose depots of lean and obese Zucker rats, inthe basal state or after catecholamine stimulation have been measured. The obeseZucker rat presents hyperinsulinemia without hyperglycemia and with elevated plasmafree fatty acids, suggesting a dyslipidemia. Morphological studies of three adiposedeposits show a marked hypertrophic and hyperplastic type of obesity, much pronouncedin the subcutaneous depot. In the current study we show that the basallipolytic rate is higher in adipocytes from each deposit of obese rats (when results arecorrected for cell surface area). This finding, associated with the increase of alldeposits, could contribute to the elevated plasma FFA observed. Investigation of theresponsiveness of dibutyril cAMP (DBcAMP) points out that the defect in the NEresponsiveness is essentially located at post-receptor level. Nevertheless, a receptordefect could not be excluded as suggested by a decrease of the â-ARs observed in alldeposits. Our study points out that the lipolytic resistance to catecholamines in adiposetissue of obese Zucker rats appears to counteract the increase in the lipolyticrate, in order to moderate the increase in plasma FFA levels that may contribute tothe hyperinsulinemia observed, characteristic of an insulino-resistant state (AU)

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Un nuevo y potente inhibidor de la neuraminidasa para el tratamiento de las infecciones gripales / Peramivir. A new and potent neuraminidase inhibitor for the treatment of influenza

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Interacciones fármaco-diana. Bases para el diseño de nuevos fármacos / No disponible

Las dianas de los fármacos comprenden una amplia variedad de componentes celulares que pueden estar presentes tanto en el hospedador como en el huésped en las enfermedades ocasionadas por un patógeno. Incluyen proteínas, ácidos nucleicos, lípidos o carbohidratos. La determinación estructural de estas dianas o de sus complejos con ligandos pueden llevarse a cabo por diversos procedimientos, fundamentalmente difracción de rayos-X y espectroscopia de RMN. La mejora de estas metodologías ha hecho que el número de complejos macromolécula-ligando resueltos y disponibles en la Base de Proteínas de Brookhaven aumente constantemente. Por esta razón, en la actualidad, el descubrimiento de nuevos fármacos se basa en la estructura de la diana en lugar de tomar como referencia la estructura de otros ligandos tal como se hacía en el pasado (AU)

The potential targets of drugs are as varied as the molecular components that make up the organism or pathogen. These include proteins, nucleic acids, lipids and carbohydrates. The structural information of these targets or complex target-ligand can be obtained by several procedures, mainly Xray crystallography or nuclear magnetic resonance spectroscopy (NMR).The improvement of the related technologies has made possible the constant increase of the number of macromolecule-ligand complexes available in the Protein Data Bank. As consequence, the discovery of the new drugs is today based in the structure of the target, instead of the structure of others ligands (AU)