title: Effect of melatonin on α-synuclein self-assembly and cytotoxicity.
abstract: α-Synuclein (αS) assembly has been implicated as a critical step in the development of Lewy body diseases such as Parkinson's disease and dementia with Lewy bodies. Melatonin (Mel), a secretory product of the pineal gland, is known to have beneficial effects such as an antioxidant function and neuroprotection. To elucidate whether Mel has an antiassembly effect, here we used circular dichroism spectroscopy, photoinduced crosslinking of unmodified proteins, thioflavin S fluorescence, size exclusion chromatography, electron microscopy and atomic force microscopy to examine the effects of Mel on the αS assembly. We also examined the effects of Mel on αS-induced cytotoxicity by assaying 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide metabolism in αS-treated, primary neuronal cells. Initial studies revealed that Mel blocked αS fibril formation as well as destabilizing preformed αS fibrils. Subsequent evaluation of the assembly-stage specificity of the effect showed that Mel was able to inhibit protofibril formation, oligomerization, and secondary structure transitions. Importantly, Mel decreased αS-induced cytotoxicity. These data suggest a mechanism of action for Mel, inhibition of assembly of toxic polymers and protection of neurons from their effect.
authors: Department of Neurology and Neurobiology and Aging, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan.
authors: Kenjiro
authors: K
authors: Ono
authors: Hideki
authors: H
authors: Mochizuki
authors: Tokuhei
authors: T
authors: Ikeda
authors: Tomoko
authors: T
authors: Nihira
authors: Jun-ichi
authors: J
authors: Takasaki
authors: David B
authors: DB
authors: Teplow
authors: Masahito
authors: M
authors: Yamada
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D000978:Antiparkinson Agents / Q000494:pharmacology; D052160:Benzothiazoles; D001921:Brain / Q000166:cytology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004622:Embryo, Mammalian; D008550:Melatonin / Q000494:pharmacology*; D051379:Mice; D008810:Mice, Inbred C57BL; D046529:Microscopy, Electron, Transmission; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism* / Q000648:ultrastructure; D017433:Protein Structure, Secondary; D012844:Sincalide / Q000494:pharmacology; D013844:Thiazoles / Q000378:metabolism; D013997:Time Factors; D014282:Trihexyphenidyl / Q000494:pharmacology; D051844:alpha-Synuclein / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D000978:Antiparkinson Agents; D052160:Benzothiazoles; D013844:Thiazoles; D051844:alpha-Synuclein; C009462:thioflavin T; D014282:Trihexyphenidyl; D008550:Melatonin; D012844:Sincalide