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Cell Mol Life Sci. 2019 Sep 27. doi: 10.1007/s00018-019-03312-0. [Epub ahead of print]

Purpurin modulates Tau-derived VQIVYK fibrillization and ameliorates Alzheimer's disease-like symptoms in animal model.

Author information

1
Department of Molecular Microbiology and Biotechnology, School of Molecular Cell Biology and Biotechnology, Tel-Aviv University, 69978, Tel Aviv, Israel.
2
Ilse Katz Institute (IKI) for Nanoscale Science and Technology, Ben Gurion University of the Negev, 8410501, Beer Sheva, Israel.
3
Department of Chemistry, Ben Gurion University of the Negev, 8410501, Beer Sheva, Israel.
4
The Joseph Sagol Neuroscience Center, Sheba Medical Center, Tel Hashomer, 52621, Ramat Gan, Israel.
5
Blavatnik Center for Drug Discovery, Tel-Aviv University, 69978, Tel Aviv, Israel.
6
Interdisciplinary Center Herzliya, Herzliya, Israel.
7
Blood-Brain Barrier Laboratory (LBHE), Université d'Artois, Lens, France.
8
Department of Molecular Microbiology and Biotechnology, School of Molecular Cell Biology and Biotechnology, Tel-Aviv University, 69978, Tel Aviv, Israel. dsegal@post.tau.ac.il.
9
The Interdisciplinary Sagol School of Neurosciences, Tel-Aviv University, 69978, Tel Aviv, Israel. dsegal@post.tau.ac.il.

Abstract

Neurofibrillary tangles of the Tau protein and plaques of the amyloid β peptide are hallmarks of Alzheimer's disease (AD), which is characterized by the conversion of monomeric proteins/peptides into misfolded β-sheet rich fibrils. Halting the fibrillation process and disrupting the existing aggregates are key challenges for AD drug development. Previously, we performed in vitro high-throughput screening for the identification of potent inhibitors of Tau aggregation using a proxy model, a highly aggregation-prone hexapeptide fragment 306VQIVYK311 (termed PHF6) derived from Tau. Here we have characterized a hit molecule from that screen as a modulator of Tau aggregation using in vitro, in silico, and in vivo techniques. This molecule, an anthraquinone derivative named Purpurin, inhibited ~ 50% of PHF6 fibrillization in vitro at equimolar concentration and disassembled pre-formed PHF6 fibrils. In silico studies showed that Purpurin interacted with key residues of PHF6, which are responsible for maintaining its β-sheets conformation. Isothermal titration calorimetry and surface plasmon resonance experiments with PHF6 and full-length Tau (FL-Tau), respectively, indicated that Purpurin interacted with PHF6 predominantly via hydrophobic contacts and displayed a dose-dependent complexation with FL-Tau. Purpurin was non-toxic when fed to Drosophila and it significantly ameliorated the AD-related neurotoxic symptoms of transgenic flies expressing WT-FL human Tau (hTau) plausibly by inhibiting Tau accumulation and reducing Tau phosphorylation. Purpurin also reduced hTau accumulation in cell culture overexpressing hTau. Importantly, Purpurin efficiently crossed an in vitro human blood-brain barrier model. Our findings suggest that Purpurin could be a potential lead molecule for AD therapeutics.

KEYWORDS:

Aggregation; Amyloid; Inhibitor; PHF6 peptide; Purpurin; Tau protein

PMID:
31562564
DOI:
10.1007/s00018-019-03312-0

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