RESUMEN
Prion diseases are characterized by the accumulation of altered forms of the prion protein (termed PrP(Sc)) in the brain. Unlike the normal protein, PrP(Sc) isoforms have a high content of beta-sheet secondary structure, are protease-resistant, and form insoluble aggregates and amyloid fibrils. Evidence indicates that they are responsible for neuropathological changes (i.e. nerve cell degeneration and glial cell activation) and transmissibility of the disease process. Here, we show that the antibiotic tetracycline: (i) binds to amyloid fibrils generated by synthetic peptides corresponding to residues 106-126 and 82-146 of human PrP; (ii) hinders assembly of these peptides into amyloid fibrils; (iii) reverts the protease resistance of PrP peptide aggregates and PrP(Sc) extracted from brain tissue of patients with Creutzfeldt-Jakob disease; (iv) prevents neuronal death and astrocyte proliferation induced by PrP peptides in vitro. NMR spectroscopy revealed several through-space interactions between aromatic protons of tetracycline and side-chain protons of Ala(117-119), Val(121-122) and Leu(125) of PrP 106-126. These properties make tetracycline a prototype of compounds with the potential of inactivating the pathogenic forms of PrP.
Asunto(s)
Proteínas PrPSc/química , Proteínas PrPSc/metabolismo , Priones/química , Tetraciclina/farmacología , Secuencia de Aminoácidos , Animales , Astrocitos/efectos de los fármacos , Astrocitos/patología , Sitios de Unión , Encéfalo/metabolismo , Encéfalo/patología , División Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Síndrome de Creutzfeldt-Jakob/tratamiento farmacológico , Síndrome de Creutzfeldt-Jakob/metabolismo , Síndrome de Creutzfeldt-Jakob/patología , Endopeptidasa K/metabolismo , Humanos , Espectroscopía de Resonancia Magnética , Datos de Secuencia Molecular , Neuronas/efectos de los fármacos , Neuronas/patología , Fármacos Neuroprotectores/química , Fármacos Neuroprotectores/metabolismo , Fármacos Neuroprotectores/farmacología , Fármacos Neuroprotectores/uso terapéutico , Fragmentos de Péptidos/química , Fragmentos de Péptidos/metabolismo , Fragmentos de Péptidos/toxicidad , Fragmentos de Péptidos/ultraestructura , Placa Amiloide/química , Placa Amiloide/metabolismo , Placa Amiloide/ultraestructura , Proteínas PrPSc/toxicidad , Proteínas PrPSc/ultraestructura , Priones/metabolismo , Priones/toxicidad , Priones/ultraestructura , Unión Proteica/efectos de los fármacos , Conformación Proteica/efectos de los fármacos , Ratas , Solubilidad/efectos de los fármacos , Tetraciclina/química , Tetraciclina/metabolismo , Tetraciclina/uso terapéuticoRESUMEN
Cerebral deposition of beta-amyloid is a major neuropathological feature in Alzheimer's disease. Here we show that tetracyclines, tetracycline and doxycycline, classical antibiotics, exhibit anti-amyloidogenic activity. This capacity was determined by the exposure of beta 1-42 amyloid peptide to the drugs followed by the electron microscopy examination of the amyloid fibrils spontaneously formed and quantified with thioflavine T binding assay. The drugs reduced also the resistance of beta 1-42 amyloid fibrils to trypsin digestion. Tetracyclines not only inhibited the beta-amyloid aggregates formation but also disassembled the pre-formed fibrils. The results indicate that drugs with a well-known clinical profile, including activity in the central nervous system, are potentially useful for Alzheimer's therapy.