RESUMO
Agents that interfere with the toxic effects of beta-amyloid protein may be therapeutically useful against Alzheimer's disease. We reported recently that several sulphated glycosaminoglycans and sulphonated dyes attenuate the toxic effects of beta-amyloid fragments beta 25-35 and beta 1-40 in two clonal cell lines. We now demonstrate that this protective effect is due to interference with beta-amyloid cell association rather than effects on beta-amyloid structure. Using an enzyme-linked immunoabsorbance assay to detect cell-associated beta 1-40, we found in a range of compounds a strong correlation between inhibition of HeLa cell association of beta 1-40 and attenuation of cellular toxicity as measured by inhibition of 3-[4,5-dimethylthia-zol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) reduction. In contrast, effects on peptide structure, as measured by Congo red binding, were generally inconsistent with the attenuating effects of the compounds on cellular toxicity. These results suggest that by binding beta-amyloid these agents prevent its interaction with cells.
Assuntos
Peptídeos beta-Amiloides/toxicidade , Estrutura Secundária de Proteína , Sulfatos/farmacologia , Ácidos Sulfônicos/farmacologia , Peptídeos beta-Amiloides/antagonistas & inibidores , Corantes , Vermelho Congo , Ensaio de Imunoadsorção Enzimática , Células HeLa , Humanos , Ligação Proteica , Sais de Tetrazólio , TiazóisRESUMO
We recently reported that several sulfate-containing glycosaminoglycans, a class of compounds associated with the beta-amyloid plaques of Alzheimer's disease, attenuate the toxic effects of beta-amyloid fragments beta 25-35 and beta 1-40. The amyloid-binding sulfonated dye Congo Red was shown to have a similar effect. Using two clonal cell lines, we now demonstrate that several sulfonated dyes attenuate beta-amyloid toxicity and that the protective effect appears specific for compounds whose sulfonate groups can interact with the beta-pleated structure of aggregated amyloid. These results suggest that by binding beta-amyloid these compounds may prevent toxic interactions of the peptide with cells.
Assuntos
Peptídeos beta-Amiloides/efeitos adversos , Peptídeos beta-Amiloides/antagonistas & inibidores , Corantes/farmacologia , Vermelho Congo/farmacologia , Sulfatos/farmacologia , Peptídeos beta-Amiloides/farmacologia , Peptídeos beta-Amiloides/toxicidade , Animais , Cromatografia Líquida de Alta Pressão , Corantes/química , Vermelho Congo/química , Células HeLa , Humanos , Células PC12 , Fragmentos de Peptídeos/farmacologia , Ratos , Relação Estrutura-Atividade , Sulfatos/químicaAssuntos
Peptídeos beta-Amiloides/toxicidade , Sobrevivência Celular/efeitos dos fármacos , Glicosaminoglicanos/farmacologia , Neurotoxinas/toxicidade , Peptídeos beta-Amiloides/antagonistas & inibidores , Peptídeos beta-Amiloides/farmacologia , Animais , Corantes , Vermelho Congo/farmacologia , Relação Dose-Resposta a Droga , Células PC12 , Fragmentos de Peptídeos/farmacologia , Ratos , Sais de Tetrazólio , TiazóisRESUMO
Glycosaminoglycan (GAG)-containing proteoglycans are associated with the neuritic plaques and cerebrovascular beta-amyloid deposits of Alzheimer's disease as well as with the amyloid deposits of prion and other disorders. GAGs and other sulfate-containing compounds have previously been shown to bind beta-amyloid peptide in vitro, suggesting possible effects of beta-amyloid deposition and/or toxicity in vivo. Using reduction of the redox dye 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) to measure beta-amyloid neurotoxicity in rat pheochromocytoma PC12 cells, several polysulfated GAGs and synthetic sulfate-containing compounds were found to attenuate the neurotoxic effects of beta-amyloid fragments beta 25-35 and beta 1-40. These results suggest that by binding beta-amyloid these compounds may prevent toxic interactions of the peptide with cells.