title: Cellular Models of Aggregation-dependent Template-directed Proteolysis to Characterize Tau Aggregation Inhibitors for Treatment of Alzheimer Disease.
abstract: Alzheimer disease (AD) is a degenerative tauopathy characterized by aggregation of Tau protein through the repeat domain to form intraneuronal paired helical filaments (PHFs). We report two cell models in which we control the inherent toxicity of the core Tau fragment. These models demonstrate the properties of prion-like recruitment of full-length Tau into an aggregation pathway in which template-directed, endogenous truncation propagates aggregation through the core Tau binding domain. We use these in combination with dissolution of native PHFs to quantify the activity of Tau aggregation inhibitors (TAIs). We report the synthesis of novel stable crystalline leucomethylthioninium salts (LMTX®), which overcome the pharmacokinetic limitations of methylthioninium chloride. LMTX®, as either a dihydromesylate or a dihydrobromide salt, retains TAI activity in vitro and disrupts PHFs isolated from AD brain tissues at 0.16 μM. The Ki value for intracellular TAI activity, which we have been able to determine for the first time, is 0.12 μM. These values are close to the steady state trough brain concentration of methylthioninium ion (0.18 μM) that is required to arrest progression of AD on clinical and imaging end points and the minimum brain concentration (0.13 μM) required to reverse behavioral deficits and pathology in Tau transgenic mice.
authors.affiliation: From the School of Medicine and Dentistry, University of Aberdeen, Aberdeen AB25 2ZP, United Kingdom, TauRx Therapeutics Ltd., Singapore 068805, and the Department of Chemistry, University of Aberdeen, Aberdeen AB24 3UE, United Kingdom c.harrington@abdn.ac.uk.
authors.forename: Charles R
authors.initials: CR
authors.lastname: Harrington
authors.affiliation: TauRx Therapeutics Ltd., Singapore 068805, and the Department of Chemistry, University of Aberdeen, Aberdeen AB24 3UE, United Kingdom.
authors.forename: John M D
authors.initials: JM
authors.lastname: Storey
authors.affiliation: the Department of Chemistry, University of Aberdeen, Aberdeen AB24 3UE, United Kingdom.
authors.forename: Scott
authors.initials: S
authors.lastname: Clunas
authors.affiliation: From the School of Medicine and Dentistry, University of Aberdeen, Aberdeen AB25 2ZP, United Kingdom.
authors.forename: Kathleen A
authors.initials: KA
authors.lastname: Harrington
authors.affiliation: From the School of Medicine and Dentistry, University of Aberdeen, Aberdeen AB25 2ZP, United Kingdom.
authors.forename: David
authors.initials: D
authors.lastname: Horsley
authors.affiliation: the Department of Chemistry, University of Aberdeen, Aberdeen AB24 3UE, United Kingdom.
authors.forename: Ahtsham
authors.initials: A
authors.lastname: Ishaq
authors.affiliation: the Department of Chemistry, University of Aberdeen, Aberdeen AB24 3UE, United Kingdom.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Kemp
authors.affiliation: the Department of Chemistry, University of Aberdeen, Aberdeen AB24 3UE, United Kingdom.
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Larch
authors.affiliation: the Department of Chemistry, University of Aberdeen, Aberdeen AB24 3UE, United Kingdom.
authors.forename: Colin
authors.initials: C
authors.lastname: Marshall
authors.affiliation: the Department of Chemistry, University of Aberdeen, Aberdeen AB24 3UE, United Kingdom.
authors.forename: Sarah L
authors.initials: SL
authors.lastname: Nicoll
authors.affiliation: From the School of Medicine and Dentistry, University of Aberdeen, Aberdeen AB25 2ZP, United Kingdom.
authors.forename: Janet E
authors.initials: JE
authors.lastname: Rickard
authors.affiliation: the Department of Chemistry, University of Aberdeen, Aberdeen AB24 3UE, United Kingdom.
authors.forename: Michael
authors.initials: M
authors.lastname: Simpson
authors.affiliation: the Department of Chemistry, University of Aberdeen, Aberdeen AB24 3UE, United Kingdom.
authors.forename: James P
authors.initials: JP
authors.lastname: Sinclair
authors.affiliation: the Department of Chemistry, University of Aberdeen, Aberdeen AB24 3UE, United Kingdom.
authors.forename: Lynda J
authors.initials: LJ
authors.lastname: Storey
authors.affiliation: From the School of Medicine and Dentistry, University of Aberdeen, Aberdeen AB25 2ZP, United Kingdom, TauRx Therapeutics Ltd., Singapore 068805, and cmw@taurx.com.
authors.forename: Claude M
authors.initials: CM
authors.lastname: Wischik
mesh_terms: D000544:Alzheimer Disease / Q000188:drug therapy* / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D002460:Cell Line; D006801:Humans; D008751:Methylene Blue / Q000031:analogs & derivatives / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D051379:Mice; D008822:Mice, Transgenic; D008954:Models, Biological; D066329:Protein Aggregates / Q000187:drug effects; D066263:Protein Aggregation, Pathological / Q000188:drug therapy* / Q000378:metabolism*; D054730:Protein Interaction Domains and Motifs; D059748:Proteolysis; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016875:tau Proteins / Q000737:chemistry* / Q000378:metabolism*
chemical_list: C054369:MAPT protein, human; D066329:Protein Aggregates; D011994:Recombinant Proteins; D016875:tau Proteins; C011010:hydromethylthionine; D008751:Methylene Blue
keywords: Alzheimer Disease; Cell Biology; LMTX; Methylthioninium; Prion-like Processing; Protein Aggregation; Tau Protein (Tau); Tauopathy