RESUMO
Under what conditions can organized labour successfully politicize the European integration process across borders? To answer this question, we compare the European Citizens' Initiatives (ECIs) of two European trade union federations: EPSU's successful Right2Water ECI and ETF's unsuccessful Fair Transport ECI. Our comparison reveals that actor-centred factors matter - namely, unions' ability to create broad coalitions. Successful transnational labour campaigns, however, also depend on structural conditions, namely, the prevailing mode of EU integration pressures faced by unions at a given time. Whereas the Right2Water ECI pre-emptively countered commodification attempts by the European Commission in water services, the Fair Transport ECI attempted to ensure fair working conditions after most of the transport sector had been liberalized. Vertical EU integration attempts that commodify public services are thus more likely to generate successful transnational counter-movements than the horizontal integration pressures on wages and working conditions that followed earlier successful EU liberalization drives.
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In this paper, we present an additional, new cage-GABA compound, called 4-amino-1-(4'-dimethylaminoisopropoxy-5',7'-dinitro-2',3'-dihydro-indol-1-yl)-1-oxobutane-γ-aminobutyric acid (iDMPO-DNI-GABA), and currently, this compound is the only photoreagent, which can be applied for GABA uncaging without experimental compromises. By a systematic theoretical design and successful synthesis of several compounds, the best reagent exhibits a high two-photon efficiency within the 700-760 nm range with excellent pharmacological behavior, which proved to be suitable for a complex epileptic study. Quantum chemical design showed that the optimal length of the cationic side chain enhances the two-photon absorption by 1 order of magnitude due to the cooperating internal hydrogen bonding to the extra nitro group on the core. This feature increased solubility while suppressing membrane permeability. The efficiency was demonstrated in a systematic, wide range of in vitro single-cell neurophysiological experiments by electrophysiological as well as calcium imaging techniques. Scalable inhibitory ion currents were elicited by iDMPO-DNI-GABA with appropriate spatial-temporal precision, blocking both spontaneous and evoked cell activity with excellent efficiency. Additionally, to demonstrate its applicability in a real neurobiological study, we could smoothly and selectively modulate neuronal activities during artificial epileptic rhythms first time in a neural network of GCaMP6f transgenic mouse brain slices.
RESUMO
Herein we comparatively comment on the molecular metric 'amidicity', a descriptor of amide reactivity, and differing methods to determining it; with focus on lactam-rings. Specifically, our established amidicity percentage (AM%) approach is quantitatively contrasted with the transamidation (TA) method. This comment is organised into two sections, firstly addressing the differing methods in context of the computational bases of amidicity. This is followed by the quantitative demonstration that although both the AM% and HRS methods provide estimates of resonance enthalpy (ΔHRE), the former is more reliable across a wider set of systems. The robustness of the AM% approach is affirmed by quantitative matching of experimental NMR and kinetics measurements tracking changes in amide reactivities, including in Penicillin arising from modulation of its amide group and environmental effects.
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Inhaled glucocorticoids form the mainstay of asthma treatment because of their anti-inflammatory effects in the lung. Exposure to the air pollutant ozone (O3) exacerbates chronic airways disease. We and others showed that presence of the epithelial-derived surfactant protein-D (SP-D) is important in immunoprotection against inflammatory changes including those induced by O3 inhalation in the airways. SP-D synthesis requires glucocorticoids. We hypothesized here that O3 exposure impairs glucocorticoid responsiveness (including SP-D production) in allergic airway inflammation. The effects of O3 inhalation and glucocorticoid treatment were studied in a mouse model of allergic asthma induced by sensitization and challenge with Aspergillus fumigatus (Af) in vivo. The role of O3 and glucocorticoids in regulation of SP-D expression was investigated in A549 and primary human type II alveolar epithelial cells in vitro. Budesonide inhibited airway hyperreactivity, eosinophil counts in the lung and bronchoalveolar lavage (BAL) and CCL11, IL-13, and IL-23p19 release in the BAL of mice sensitized and challenged with Af (p < 0.05). The inhibitory effects of budesonide were attenuated on inflammatory changes and were completely abolished on airway hyperreactivity after O3 exposure of mice sensitized and challenged with Af. O3 stimulated release of pro-neutrophilic mediators including CCL20 and IL-6 into the airways and impaired the inhibitory effects of budesonide on CCL11, IL-13 and IL-23. O3 also prevented budesonide-induced release of the immunoprotective lung collectin SP-D into the airways of allergen-challenged mice. O3 had a bi-phasic direct effect with early (<12 h) inhibition and late (>48 h) activation of SP-D mRNA (sftpd) in vitro. Dexamethasone and budesonide induced sftpd transcription and translation in human type II alveolar epithelial cells in a glucocorticoid receptor and STAT3 (an IL-6 responsive transcription factor) dependent manner. Our study indicates that O3 exposure counteracts the effects of budesonide on airway inflammation, airway hyperreactivity, and SP-D production. We speculate that impairment of SP-D expression may contribute to the acute O3-induced airway inflammation. Asthmatics exposed to high ambient O3 levels may become less responsive to glucocorticoid treatment during acute exacerbations.
Assuntos
Aspergillus fumigatus/imunologia , Asma/prevenção & controle , Budesonida/farmacologia , Inflamação/prevenção & controle , Pulmão/efeitos dos fármacos , Ozônio/administração & dosagem , Células A549 , Administração por Inalação , Alérgenos/imunologia , Animais , Asma/imunologia , Líquido da Lavagem Broncoalveolar/química , Líquido da Lavagem Broncoalveolar/citologia , Budesonida/administração & dosagem , Células Cultivadas , Quimiocina CCL11/metabolismo , Eosinófilos/metabolismo , Glucocorticoides/administração & dosagem , Glucocorticoides/farmacologia , Humanos , Inflamação/imunologia , Interleucina-13/metabolismo , Pulmão/imunologia , Pulmão/patologia , Camundongos Endogâmicos BALB C , Oxidantes Fotoquímicos/administração & dosagem , Proteína D Associada a Surfactante Pulmonar/genética , Proteína D Associada a Surfactante Pulmonar/imunologia , Proteína D Associada a Surfactante Pulmonar/metabolismoRESUMO
In order to study the effects of peptide exposure to oxidative attack, we chose a model reaction in which the hydroxyl radical discretely abstracts a hydrogen atom from the α-carbon of each residue of a highly amyloidogenic region in the human calcitonin hormone, hCT15-19. Based on a combined Molecular Mechanics / Quantum Mechanics approach, the extended and folded L- and D-configuration and radical intermediate hCT15-19 peptides were optimized to obtain their compactness, secondary structure and relative thermodynamic data. The results suggest that the epimerization of residues is generally an exergonic process that can explain the cumulative nature of molecular aging. Moreover, the configurational inversion induced conformational changes can cause protein dysfunction. The epimerization of the central residue to the D-configuration induced a hairpin structure in hCT15-19, concomitant with a possible oligomerization of human calcitonin into Aß(1-42)-like amyloid fibrils present in patients suffering from Alzheimer's disease.
Assuntos
Proteínas Amiloidogênicas/química , Calcitonina/química , Fragmentos de Peptídeos/química , Peptídeos beta-Amiloides/química , Teoria da Densidade Funcional , Humanos , Ligação de Hidrogênio , Modelos Químicos , Simulação de Dinâmica Molecular , Oxirredução , Estrutura Secundária de Proteína , Estereoisomerismo , TermodinâmicaRESUMO
In order to improve the fluorescence properties of the green fluorescent protein chromophore, pHOBDI ((5(4hydroxybenzylidene)2,3dimethyl3,5dihydro4Himidazol4one), sixteen dihydroimidazolone derivates were synthesized from thiohydantoin and arylaldehydes. The synthesis developed is an efficient, novel, one-pot procedure. The study provides a detailed description of the spectroscopic characteristics of the newly synthesized compounds, using pHOBDI as a reference. The new compounds all exhibited significantly stronger fluorescence than pHOBDI, up to 28 times higher quantum yields. An experimental and theoretical investigation of the relationship of the fluorescence properties with the molecular structure was also carried out. A good correlation was found between the emission wavenumber and the Hammett constant of the functional group, which suggests the intermolecular charge transfer (ICT) mechanism between the aromatic groups.
Assuntos
Corantes Fluorescentes/química , Proteínas de Fluorescência Verde/química , Imidazóis/química , Aminação , Técnicas de Química Combinatória , Fluorescência , Corantes Fluorescentes/síntese química , Imidazóis/síntese química , Modelos Moleculares , Espectrometria de FluorescênciaRESUMO
The formation of polycyclic aromatic hydrocarbons (PAHs) is a strong global concern due to their harmful effects. To help the reduction of their emissions, a crucial understanding of their formation and a deep exploration of their growth mechanism is required. In the present work, the formation of benzo(a)pyrene was investigated computationally employing chrysene and benz(a)anthracene as starting materials. It was assumed a type of methyl addition/cyclization (MAC) was the valid growth mechanism in this case. Consequently, the reactions implied addition reactions, ring closures, hydrogen abstractions and intramolecular hydrogen shifts. These steps of the mechanism were computed to explore benzo(a)pyene formation. The corresponding energies of the chemical species were determined via hybrid density funcional theory (DFT), B3LYP/6-31+G(d,p) and M06-2X/6-311++G(d,p). Results showed that the two reaction routes had very similar trends energetically, the difference between the energy levels of the corresponding molecules was just 6.13 kJ/mol on average. The most stable structure was obtained in the benzo(a)anthracene pathway.
Assuntos
Benzo(a)Antracenos/química , Benzo(a)pireno/química , Carcinógenos/química , Hidrocarbonetos Policíclicos Aromáticos/química , Benzo(a)Antracenos/toxicidade , Benzo(a)pireno/toxicidade , Carcinógenos/toxicidade , Crisenos/química , Humanos , Hidrogênio/química , Estrutura Molecular , Hidrocarbonetos Policíclicos Aromáticos/toxicidadeRESUMO
Not all amide bonds are created equally. The purpose of the present paper is the reinterpretation of the amide group by means of two concepts: amidicity and carbonylicity. These concepts are meant to provide a new viewpoint in defining the stability and reactivity of amides. With the help of simple quantum-chemical calculations, practicing chemists can easily predict the outcome of a desired process. The main benefit of the concepts is their simplicity. They provide intuitive, but quasi-thermodynamic data, making them a practical rule of thumb for routine use. In the current paper we demonstrate the performance of our methods to describe the chemical character of an amide bond strength and the way of its activation methods. Examples include transamidation, acyl transfer and amide reductions. Also, the method is highly capable for simple interpretation of mechanisms for biological processes, such as protein splicing and drug mechanisms. Finally, we demonstrate how these methods can provide information about photo-activation of amides, through the examples of two caged neurotransmitter derivatives.
Assuntos
Amidas/química , Modelos Químicos , Algoritmos , Amidas/síntese química , Técnicas de Química Sintética , TermodinâmicaRESUMO
The asthmatic airways are highly susceptible to inflammatory injury by air pollutants such as ozone (O3 ), characterized by enhanced activation of eosinophilic granulocytes and a failure of immune protective mechanisms. Eosinophil activation during asthma exacerbation contributes to the proinflammatory oxidative stress by high levels of nitric oxide (NO) production and extracellular DNA release. Surfactant protein-D (SP-D), an epithelial cell product of the airways, is a critical immune regulatory molecule with a multimeric structure susceptible to oxidative modifications. Using recombinant proteins and confocal imaging, we demonstrate here that SP-D directly bound to the membrane and inhibited extracellular DNA trap formation by human and murine eosinophils in a concentration and carbohydrate-dependent manner. Combined allergic airway sensitization and O3 exposure heightened eosinophilia and nos2 mRNA (iNOS) activation in the lung tissue and S-nitrosylation related de-oligomerisation of SP-D in the airways. In vitro reproduction of the iNOS action led to similar effects on SP-D. Importantly, S-nitrosylation abolished the ability of SP-D to block extracellular DNA trap formation. Thus, the homeostatic negative regulatory feedback between SP-D and eosinophils is destroyed by the NO-rich oxidative lung tissue environment in asthma exacerbations.
Assuntos
Asma/imunologia , Eosinófilos/imunologia , Armadilhas Extracelulares/imunologia , Estresse Oxidativo/imunologia , Proteína D Associada a Surfactante Pulmonar/metabolismo , Animais , Asma/metabolismo , Células Cultivadas , Eosinófilos/efeitos dos fármacos , Eosinófilos/metabolismo , Armadilhas Extracelulares/metabolismo , Humanos , Hipersensibilidade/imunologia , Hipersensibilidade/metabolismo , Camundongos , Oxidantes Fotoquímicos/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Ozônio/toxicidadeRESUMO
Two-photon (TP) uncaging of neurotransmitter molecules is the method of choice to mimic and study the subtleties of neuronal communication either in the intact brain or in slice preparations. However, the currently available caged materials are just at the limit of their usability and have several drawbacks. The local and focal nature of their use may for example be jeopardized by a high spontaneous hydrolysis rate of the commercially available compounds with increased photochemical release rate. Here, using quantum chemical modelling we show the mechanisms of hydrolysis and two-photon activation, and synthesized more effective caged compounds. Furthermore, we have developed a new enzymatic elimination method removing neurotransmitters inadvertently escaping from their compound during experiment. This method, usable both in one and two-photon experiments, allows for the use of materials with an increased rate of photochemical release. The efficiency of the new compound and the enzymatic method and of the new compound are demonstrated in neurophysiological experiments.
RESUMO
CHF6001 is a new and potent PDE4 inhibitor for the treatment of human lung diseases, designed for topical administration by inhalation. In preclinical assessment CHF6001 appeared safe and devoid of emetic effect, which is typical side effect of PDE4 inhibitors in humans. CHF6001 absorption, distribution and excretion were evaluated in rats by PO and IV administration of [14C]CHF6001; additionally the role of transporters was investigated by using transfected cells expressing either human transporters or MDR1 and BCRP KO mice. [14C]CHF6001 intravenously administered as bolus distributed in all the tissues (with very low levels in brain and fetus) and it was mainly eliminated in bile. Following oral administration [14C]CHF6001 about half of the dose was absorbed through the gut. In vitro, CHF6001 was a substrate of human membrane transporters MDR1 and BCRP. In wild and BCRP KO mice CHF6001 was not detectable in brain, whereas it was measurable in Mdr1a/b KO mice. Therefore, in animal species Mdr1a/b plays a significant role in CHF6001 disposition, limiting its distribution into brain and contributing to the safety profile observed in preclinical evaluation. This behavior was confirmed by the results of the first human studies, where CHF6001 was safe and with no emetic effect at all the evaluated doses.
Assuntos
Proteínas de Membrana Transportadoras/metabolismo , Inibidores da Fosfodiesterase 4/metabolismo , Roedores/metabolismo , Sulfonamidas/metabolismo , para-Aminobenzoatos/metabolismo , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/metabolismo , Administração Oral , Animais , Feminino , Humanos , Masculino , Camundongos , Camundongos Knockout , Ratos , Ratos Sprague-DawleyRESUMO
Glycine (Gly) residues are particularly susceptible to hydrogen abstraction; which results in the formation of the capto-dative stabilized Cα-centered Gly radical (GLR) on the protein backbone. We examined the effect of GLR formation on the structure of the Trp cage; tryptophan zipper; and the villin headpiece; three fast-folding and stable miniproteins; using all-atom (OPLS-AA) molecular dynamics simulations. Radicalization changes the conformation of the GLR residue and affects both neighboring residues but did not affect the stability of the Trp zipper. The stability of helices away from the radical center in villin were also affected by radicalization; and GLR in place of Gly15 caused the Trp cage to unfold within 1 µs. These results provide new evidence on the destabilizing effects of protein oxidation by reactive oxygen species.
Assuntos
Glicina/química , Estabilidade Proteica , Desdobramento de Proteína , Proteínas/química , Ligação de Hidrogênio , Espectroscopia de Ressonância Magnética , Proteínas dos Microfilamentos/química , Simulação de Dinâmica Molecular , Oxirredução , Conformação ProteicaRESUMO
We examined the effects of Cα-centered radical formation on the stability of a model helical peptide, N-Ac-KK(AL)10KK-NH2. Three, 100 ns molecular dynamics simulations using the OPLS-AA force field were carried out on each α-helical peptide in six distinct binary TIP4P water/2,2,2-trifluoroethanol (TFE) mixtures. The α-helicity was at a maximum in 20% TFE, which was inversely proportional to the number of H-bonds between water molecules and the peptide backbone. The radial distribution of TFE around the peptide backbone was highest in 20% TFE, which enhanced helix stability. The Cα-centered radical initiated the formation of a turn within 5 ns, which was a smaller kink at high TFE concentrations, and a loop at lower TFE concentrations. The highest helicity of the peptide radical was measured in 100% TFE. The formation of hydrogen bonds between the peptide backbone and water destabilized the helix, whereas the clustering of TFE molecules around the radical center stabilized the helix. Following radical termination, the once helical structure converted to a ß-sheet rich state in 100% water only, and this transition did not occur in the nonradical control peptide. This study gives evidence on how the formation of peptide radicals can initiate α-helical to ß-sheet transitions under oxidative stress conditions.
Assuntos
Peptídeos/química , Solventes/química , Sequência de Aminoácidos , Análise por Conglomerados , Ligação de Hidrogênio , Simulação de Dinâmica Molecular , Estrutura Secundária de Proteína , Desdobramento de Proteína , Trifluoretanol/química , Água/químicaRESUMO
The roles of NK cells, surfactant protein D (SP-D), and IFN-γ, as well as the effect of ozone (O3) inhalation, were studied on recirculation of pulmonary dendritic cells (DC) to the mediastinal lymph nodes. O3 exposure and lack of SP-D reduced NK cell IFN-γ and lung tissue CCL21 mRNA expression and impaired DC homing to the mediastinal lymph nodes. Notably, addition of recombinant SP-D to naive mononuclear cells stimulated IFN-γ release in vitro. Because NKp46, a glycosylated membrane receptor, was necessary for dose-dependent SP-D binding to NK cells in vitro and DC migration in vivo, we speculate that SP-D may constitutively stimulate IFN-γ production by NK cells, possibly via NKp46. This mechanism could then initiate the IFN-γ/IL-12 feedback circuit, a key amplifier of DC lymph node homing. Inhibition of this process during an acute inflammatory response causes DC retention in the peripheral lung tissue and contributes to injury.
Assuntos
Quimiotaxia de Leucócito/efeitos dos fármacos , Células Dendríticas/imunologia , Células Matadoras Naturais/imunologia , Linfonodos/imunologia , Ozônio/toxicidade , Proteína D Associada a Surfactante Pulmonar/imunologia , Animais , Citometria de Fluxo , Interferon gama , Pulmão/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Pneumonia/imunologia , Reação em Cadeia da Polimerase em Tempo RealRESUMO
BACKGROUND: Asthmatic patients are highly susceptible to air pollution and in particular to the effects of ozone (O3) inhalation, but the underlying mechanisms remain unclear. OBJECTIVE: Using mouse models of O3-induced airway inflammation and airway hyperresponsiveness (AHR), we sought to investigate the role of the recently discovered group 2 innate lymphoid cells (ILC2s). METHODS: C57BL/6 and BALB/c mice were exposed to Aspergillus fumigatus, O3, or both (3 ppm for 2 hours). ILC2s were isolated by means of fluorescence-activated cell sorting and studied for Il5 and Il13 mRNA expression. ILC2s were depleted with anti-Thy1.2 mAb and replaced by means of intratracheal transfer of ex vivo expanded Thy1.1 ILC2s. Cytokine levels (ELISA and quantitative PCR), inflammatory cell profile, and AHR (flexiVent) were assessed in the mice. RESULTS: In addition to neutrophil influx, O3 inhalation elicited the appearance of eosinophils and IL-5 in the airways of BALB/c but not C57BL/6 mice. Although O3-induced expression of IL-33, a known activator of ILC2s, in the lung was similar between these strains, isolated pulmonary ILC2s from O3-exposed BALB/c mice had significantly greater Il5 and Il13 mRNA expression than C57BL/6 mice. This suggested that an altered ILC2 function in BALB/c mice might mediate the increased O3 responsiveness. Indeed, anti-Thy1.2 treatment abolished but ILC2s added back dramatically enhanced O3-induced AHR. CONCLUSIONS: O3-induced activation of pulmonary ILC2s was necessary and sufficient to mediate asthma-like changes in BALB/c mice. This previously unrecognized role of ILC2s might help explain the heightened susceptibility of human asthmatic airways to O3 exposure.
Assuntos
Imunidade Inata , Subpopulações de Linfócitos/imunologia , Subpopulações de Linfócitos/metabolismo , Ozônio/efeitos adversos , Hipersensibilidade Respiratória/etiologia , Alérgenos/imunologia , Animais , Citocinas/metabolismo , Modelos Animais de Doenças , Exposição Ambiental/efeitos adversos , Eosinofilia/etiologia , Ativação Linfocitária/imunologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Testes de Função Respiratória , Hipersensibilidade Respiratória/patologia , Hipersensibilidade Respiratória/fisiopatologiaRESUMO
Complement is implicated in asthma pathogenesis, but its mechanism of action in this disease remains incompletely understood. In this study, we investigated the role of properdin (P), a positive alternative pathway complement regulator, in allergen-induced airway inflammation. Allergen challenge stimulated P release into the airways of asthmatic patients, and P levels positively correlated with proinflammatory cytokines in human bronchoalveolar lavage (BAL). High levels of P were also detected in the BAL of OVA-sensitized and challenged but not naive mice. Compared with wild-type (WT) mice, P-deficient (P(-/-)) mice had markedly reduced total and eosinophil cell counts in BAL and significantly attenuated airway hyperresponsiveness to methacholine. Ab blocking of P at both sensitization and challenge phases or at challenge phase alone, but not at sensitization phase alone, reduced airway inflammation. Conversely, intranasal reconstitution of P to P(-/-) mice at the challenge phase restored airway inflammation to wild-type levels. Notably, C3a levels in the BAL of OVA-challenged P(-/-) mice were significantly lower than in wild-type mice, and intranasal coadministration of an anti-C3a mAb with P to P(-/-) mice prevented restoration of airway inflammation. These results show that P plays a key role in allergen-induced airway inflammation and represents a potential therapeutic target for human asthma.
Assuntos
Asma/imunologia , Complemento C3a/biossíntese , Properdina/imunologia , Células Th17/imunologia , Células Th2/imunologia , Animais , Asma/induzido quimicamente , Asma/patologia , Líquido da Lavagem Broncoalveolar/química , Líquido da Lavagem Broncoalveolar/citologia , Complemento C3a/imunologia , Eosinófilos/imunologia , Humanos , Inflamação/imunologia , Contagem de Leucócitos , Pulmão/imunologia , Pulmão/patologia , Cloreto de Metacolina/farmacologia , Camundongos , Camundongos Endogâmicos C57BL , Properdina/genéticaRESUMO
The energetics of peptide bond formation is an important factor not only in the design of chemical peptide synthesis, but it also has a role in protein biosynthesis. In this work, quantum chemical calculations at 10 different levels of theory including G3MP2B3 were performed on the energetics of glutathione formation. The strength of the peptide bond is found to be closely related to the acid strength of the to-be N-terminal and the basicity of the to-be C-terminal amino acid. It is shown that the formation of the first peptide activates the amino acid for the next condensation step, manifested in bacterial protein synthesis where the first step is the formation of an N-formylmethionine dipeptide. The possible role of glutathione in prebiotic molecular evolution is also analyzed. The implications of the thermodynamics of peptide bond formation in prebiotic peptide formation as well as in the preference of α- instead of ß- or γ-amino acids are discussed. An empirical correction is proposed for the compensation of the error due to the incapability of continuum solvation models in describing the change of the first solvation shell when a peptide bond is formed from two zwitterions accompanied by the disappearance of one ion pair.
Assuntos
Glutationa/química , Peptídeos/química , Proteínas de Bactérias/biossíntese , Proteínas de Bactérias/química , Simulação de Dinâmica Molecular , Peptídeos/metabolismo , Teoria Quântica , TermodinâmicaRESUMO
Caspase-2 represents the most conserved member of the caspase family, which exhibits features of both initiator and effector caspases. Using ribonucleoprotein (RNP)-immunoprecipitation assay, we identified the proapoptotic caspase-2L encoding mRNA as a novel target of the ubiquitous RNA-binding protein HuR in DLD-1 colon carcinoma cells. Unexpectedly, crosslinking-RNP and RNA probe pull-down experiments revealed that HuR binds exclusively to the caspase-2-5' untranslated region (UTR) despite that the 3' UTR of the mRNA bears several adenylate- and uridylate-rich elements representing the prototypical HuR binding sites. By using RNAi-mediated loss-of-function approach, we observed that HuR regulates the mRNA and in turn the protein levels of caspase-2 in a negative manner. Silencing of HuR did not affect the stability of caspase-2 mRNA but resulted in an increased redistribution of caspase-2 transcripts from RNP particles to translational active polysomes implicating that HuR exerts a direct repressive effect on caspase-2 translation. Consistently, in vitro translation of a luciferase reporter gene under the control of an upstream caspase-2-5'UTR was strongly impaired after the addition of recombinant HuR, whereas translation of caspase-2 coding region without the 5'UTR is not affected by HuR confirming the functional role of the caspase-2-5'UTR. Functionally, an elevation in caspase-2 level by HuR knockdown correlated with an increased sensitivity of cells to apoptosis induced by staurosporine- and pore-forming toxins as implicated by their significant accumulation in the sub G1 phase and an increase in caspase-2, -3 and poly ADP-ribose polymerase cleavage, respectively. Importantly, HuR knockdown cells remained insensitive toward STS-induced apoptosis if cells were additionally transfected with caspase-2-specific siRNAs. Collectively, our findings support the hypothesis that HuR by acting as an endogenous inhibitor of caspase-2-driven apoptosis may essentially contribute to the antiapoptotic program of adenocarcinoma cells by HuR.
Assuntos
Adenocarcinoma/genética , Apoptose , Caspase 2/genética , Neoplasias do Colo/genética , Cisteína Endopeptidases/genética , Proteínas ELAV/metabolismo , Regiões 3' não Traduzidas , Regiões 5' não Traduzidas , Adenocarcinoma/enzimologia , Adenocarcinoma/metabolismo , Adenocarcinoma/fisiopatologia , Caspase 2/metabolismo , Linhagem Celular Tumoral , Neoplasias do Colo/enzimologia , Neoplasias do Colo/metabolismo , Neoplasias do Colo/fisiopatologia , Cisteína Endopeptidases/metabolismo , Proteínas ELAV/genética , Humanos , Ligação Proteica , Biossíntese de Proteínas , Transcrição Gênica , Regulação para CimaRESUMO
The epimerization of amino acid residues increases with age in living organisms. In the present study, the structural consequences and thermodynamic functions of the epimerization of thymopentin (TP-5), the active site of the thymic hormone thymopoietin, were studied using molecular dynamics and density functional theory methods. The results show that free radical-initiated D-amino acid formation is energetically favoured (-130 kJmol(-1)) for each residue and induces significant changes to the peptide structure. In comparison to the wild-type (each residue in the L-configuration), the radius of gyration of the D-Asp(3) epimer of the peptide decreased by 0.5 Å, and disrupted the intramolecular hydrogen bonding of the native peptide. Beyond establishing important structural, energetic and thermodynamic benchmarks and reference data for the structure of TP-5, these results disseminate the understanding of molecular ageing, the epimerization of amino acid residues.