Doxycycline leads to the formation of off-pathway non toxic alpha-Synucleinoligomers

GONZALES LIZARRAGA, MF; TORRES-BUGEAU C.; SOCIAS, SERGIO BENJAMIN; AVILA C.; BARBOSA L.; ITRI R.; PAPY GARCÍA D.; RAISMAN VOZARI R.; CHEHÍN R.

Sierra de la Ventana - Buenos Aires

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Biosfísica; 2014

Sociedad Argentina de Biofísica

The dopaminergic neuronal loss observed in Parkinson disease has been linked to the pathological aggregation of alpha-synuclein. Although this proteinis mainly found in the cytosol, the presence of misfolded or aggregated alpha-synuclein in blood and cerebrospinal fluid suggests that it might play a role also at extracellular level. Indeed exposure to extracellular pre-aggreated alpha-synuclein induces cytotoxicity in primary glia and human neuroblastoma cell cultures. Recently, an important number of studies showed that tetracyclines have remarkable neuroprotective properties in Parkinsons disease animal models. In this work we explore the mechanism by which doxycycline, a semi-synthetic second-generation tetracycline, is able to exert such a protection against alpha-synuclein mediated toxicity.Through small angle x-ray diffraction and infrared spectroscopy we showed that doxycycline is able to affect the rate of alpha-synuclein oligomersformation. Moreover, using MTT viability assay, we observed that oligomers formed in the presence of doxycycline show decreased toxicity against dopaminergic cells. These oligomers seem to be off-pathway since they are not able to form fibrils detectable by means of ThT fluorescence assay or electronic microscopy. We propose that doxycycline is able to modify the aggregation pathway of alpha-synuclein leading to the formation of a nontoxic oligomer by binding to tyrosine residues as demonstrated by fluorescence quenching assays. This study represents a milestone in the assessment of the feasibility of using doxycycline as a therapeutic agent in the treatment of Parkinsons disease.