Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 2 de 2
Filtrar
Mais filtros

Base de dados
Ano de publicação
Tipo de documento
Intervalo de ano de publicação
1.
Diabetologia ; 54(9): 2337-46, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21547497

RESUMO

AIMS/HYPOTHESIS: Pro-atherogenic and pro-oxidant, oxidised LDL trigger adverse effects on pancreatic beta cells, possibly contributing to diabetes progression. Because oxidised LDL diminish the expression of genes regulated by the inducible cAMP early repressor (ICER), we investigated the involvement of this transcription factor and of oxidative stress in beta cell failure elicited by oxidised LDL. METHODS: Isolated human and rat islets, and insulin-secreting cells were cultured with human native or oxidised LDL or with hydrogen peroxide. The expression of genes was determined by quantitative real-time PCR and western blotting. Insulin secretion was monitored by EIA kit. Cell apoptosis was determined by scoring cells displaying pycnotic nuclei. RESULTS: Exposure of beta cell lines and islets to oxidised LDL, but not to native LDL raised the abundance of ICER. Induction of this repressor by the modified LDL compromised the expression of important beta cell genes, including insulin and anti-apoptotic islet brain 1, as well as of genes coding for key components of the secretory machinery. This led to hampering of insulin production and secretion, and of cell survival. Silencing of this transcription factor by RNA interference restored the expression of its target genes and alleviated beta cell dysfunction and death triggered by oxidised LDL. Induction of ICER was stimulated by oxidative stress, whereas antioxidant treatment with N-acetylcysteine or HDL prevented the rise of ICER elicited by oxidised LDL and restored beta cell functions. CONCLUSIONS/INTERPRETATION: Induction of ICER links oxidative stress to beta cell failure caused by oxidised LDL and can be effectively abrogated by antioxidant treatment.


Assuntos
Modulador de Elemento de Resposta do AMP Cíclico/fisiologia , Células Secretoras de Insulina/fisiologia , Ilhotas Pancreáticas/fisiopatologia , Estresse Oxidativo/fisiologia , Acetilcisteína/farmacologia , Animais , Antioxidantes/farmacologia , Apoptose/efeitos dos fármacos , Células Cultivadas , Modulador de Elemento de Resposta do AMP Cíclico/efeitos dos fármacos , Modulador de Elemento de Resposta do AMP Cíclico/genética , Humanos , Peróxido de Hidrogênio/farmacologia , Insulina/metabolismo , Células Secretoras de Insulina/citologia , Células Secretoras de Insulina/efeitos dos fármacos , Ilhotas Pancreáticas/citologia , Ilhotas Pancreáticas/efeitos dos fármacos , Lipoproteínas LDL/farmacologia , Masculino , Modelos Animais , Estresse Oxidativo/efeitos dos fármacos , RNA Interferente Pequeno/farmacologia , Ratos , Ratos Sprague-Dawley
2.
Recept Channels ; 5(2): 53-60, 1998.
Artigo em Inglês | MEDLINE | ID: mdl-9606710

RESUMO

The 5' untranslated leader sequence from the encephalomyocarditis virus was used to engineer bicistronic or tricistronic expression vectors encoding two subunits (P2X2 and P2X3) of an ATP-gated cation channel. Human embryonic kidney (293) and chinese hamster ovary (CHO-K1) cells were transfected with the vector, and stable cell lines were generated by single cell subcloning. Selection was made in a 96-well format on the basis of a sustained increase in intracellular calcium (fluorescence of Fluo3-loaded cells) evoked by the ATP analog alpha beta methylene ATP. A high proportion of transformants expressed heteromeric receptors containing both P2X2 and P2X3 subunits, as evidenced by a nondesensitizing current in response to alpha beta methylene ATP. The method is fast and simple and could be generally useful for the stable expression of heteromultimeric channel proteins.


Assuntos
Canais de Cálcio/genética , Clonagem Molecular/métodos , Vírus da Encefalomiocardite , Vetores Genéticos , Receptores Purinérgicos P2/genética , Trifosfato de Adenosina/análogos & derivados , Trifosfato de Adenosina/farmacologia , Animais , Células CHO , Canais de Cálcio/biossíntese , Linhagem Celular , Cricetinae , Expressão Gênica , Humanos , Receptores Purinérgicos P2/biossíntese , Receptores Purinérgicos P2X2 , Receptores Purinérgicos P2X3 , Proteínas Recombinantes de Fusão/biossíntese , Proteínas Recombinantes de Fusão/genética
SELEÇÃO DE REFERÊNCIAS
Detalhe da pesquisa