RESUMO
We used a beta-amyloid precursor protein (APP) transgenic (Tg) mouse model that displays some of the typical Alzheimer-associated pathological features to study the brain proteoma associated with amyloid plaque deposition. Two groups (male and female) of 14-month-old Tg mice were compared with their wild type littermates. We used differential 2D electrophoresis coupled with mass spectrometry to generate one of the first complete image of changes in brain protein expression occurring in this well-recognized model of Alzheimer's disease (AD). We identified 15 different proteins, which are significantly regulated in this pathology (p<0.05, > or =1.5-fold variation in expression comparing with the wild type samples). These comprise a number of proteins that were already known to be implicated in AD and neurodegeneration, as well as several proteins which relationship with AD had not been shown before. Identified proteins were grouped according to their biological key pathways. Results obtained are discussed in view of existing bibliographic data on human AD transcriptoma and proteoma.
Assuntos
Doença de Alzheimer/genética , Doença de Alzheimer/patologia , Encéfalo/metabolismo , Eletroforese em Gel Bidimensional/métodos , Proteômica/métodos , Precursor de Proteína beta-Amiloide/genética , Animais , Apolipoproteínas E/metabolismo , Western Blotting/métodos , Encéfalo/patologia , Diagnóstico por Imagem/métodos , Modelos Animais de Doenças , Feminino , Proteína Glial Fibrilar Ácida/metabolismo , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodosRESUMO
Clofibrate is a peroxisome proliferator known to induce liver tumours in rats. A proteomics study was conducted to provide new insights into the molecular mechanisms of clofibrate-induced non-genotoxic hepatocarcinogenesis. Rats were treated with 250 mg/kg day clofibrate orally and sacrificed after 7 days. Proteins extracted from the liver were analysed by 2-DE using DIGE technology. The protein identification performed by MS showed that clofibrate induced up-regulation of 77 proteins and down-regulation of 27 proteins. The highest expression ratios corresponded to proteins involved in a series of biochemical pathways such as lipid metabolism, fatty acid metabolism, amino acid metabolism, protein metabolism, citric acid cycle, xenobiotic detoxification and oxidative stress. Proteins implicated in cell proliferation and apoptosis, such as prohibitin, 10-formyl tetrahydrofolate dehydrogenase, senescence marker protein-30, pyridoxine 5'-phosphate oxidase and vimentin, were also identified as being regulated. These results provide leads for further investigations into the molecular mechanisms of liver tumours induced by clofibrate. In addition, MS results showed that a series of regulated proteins were detected as several spots corresponding to different pI and/or M(r). Differential effects on those variants could result from specific PTM and could be a specific molecular signature of the clofibrate-induced protein expression modulation in rat liver.
Assuntos
Clofibrato/farmacologia , Fígado/efeitos dos fármacos , Proteínas/metabolismo , Proteômica/métodos , Sequência de Aminoácidos , Animais , Cromatografia Líquida , Regulação para Baixo/efeitos dos fármacos , Eletroforese em Gel Bidimensional , Regulação Enzimológica da Expressão Gênica , Concentração de Íons de Hidrogênio , Fígado/metabolismo , Fígado/patologia , Extratos Hepáticos/metabolismo , Masculino , Espectrometria de Massas , Dados de Sequência Molecular , Mapeamento de Peptídeos , Proteínas/química , Proteínas/isolamento & purificação , Ratos , Ratos Sprague-Dawley , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Tripsina/farmacologia , Regulação para Cima/efeitos dos fármacosRESUMO
To investigate the effect of the autoinducer AI-2 on protein expression in Neisseria meningitidis, a luxS mutant of strain MC58 was grown in the presence and absence of in vitro-produced AI-2, and differential protein expression was assessed by two-dimensional differential gel electrophoresis. N. meningitidis did not show a global response to AI-2 signaling activity.
Assuntos
Proteínas de Bactérias/análise , Homosserina/análogos & derivados , Homosserina/fisiologia , Neisseria meningitidis/metabolismo , Proteínas de Bactérias/fisiologia , Liases de Carbono-Enxofre , Eletroforese em Gel Bidimensional , Lactonas , Proteômica , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por MatrizRESUMO
Alternative initiation of translation of the human fibroblast growth factor 2 (FGF-2) mRNA at five in-frame CUG or AUG translation initiation codons requires various RNA cis-acting elements, including an internal ribosome entry site (IRES). Here we describe the purification of a trans-acting factor controlling FGF-2 mRNA translation achieved by several biochemical purification approaches. We have identified the heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) as a factor that binds to the FGF-2 5'-leader RNA and that also complements defective FGF-2 translation in vitro in rabbit reticulocyte lysate. Recombinant hnRNP A1 stimulates in vitro translation at the four IRES-dependent initiation codons but has no effect on the cap-dependent initiation codon. Consistent with a role of hnRNP A1 in the control of alternative initiation of translation, short interfering RNA-mediated knock down of hnRNP A1 specifically inhibits translation at the four IRES-dependent initiation codons. Furthermore, hnRNP A1 binds to the FGF-2 IRES, implicating this interaction in the control of alternative initiation of translation.
