title: Thr175-phosphorylated tau induces pathologic fibril formation via GSK3β-mediated phosphorylation of Thr231 in vitro.
abstract: We have previously shown that amyotrophic lateral sclerosis with cognitive impairment can be characterized by pathologic inclusions of microtubule-associated protein tau (tau) phosphorylated at Thr(175) (pThr(175)) in association with GSK3β activation. We have now examined whether pThr(175) induces GSK3β activation and whether this leads to pathologic fibril formation through Thr(231) phosphorylation. Seventy-two hours after transfection of Neuro2A cells with pseudophosphorylated green fluorescent protein-tagged 2N4R tau (Thr(175)Asp), phosphorylated kinase glycogen synthase kinase 3 beta (active GSK3β) levels were significantly increased as was pathologic fibril formation and cell death. Treatment with each of 4 GSK3β inhibitors or small hairpin RNA knockdown of GSK3β abolished fibril formation and prevented cell death. Inhibition of Thr(231) phosphorylation (Thr(231)Ala) prevented pathologic tau fibril formation, regardless of Thr(175) state, whereas Thr(231)Asp (pseudophosphorylated at Thr(231)) developed pathologic tau fibrils. Ser(235) mutations did not affect fibril formation, indicating an unprimed mechanism of Thr(231) phosphorylation. These findings suggest a mechanism of tau pathology by which pThr(175) induces GSK3β phosphorylation of Thr(231) leading to fibril formation, indicating a potential therapeutic avenue for amyotrophic lateral sclerosis with cognitive impairment.
authors.affiliation: Graduate Program in Neuroscience, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada; Robarts Research Institute, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada.
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Moszczynski
authors.affiliation: Robarts Research Institute, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada.
authors.forename: May
authors.initials: M
authors.lastname: Gohar
authors.affiliation: Robarts Research Institute, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada; Department of Clinical Neurological Sciences, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada.
authors.forename: Kathryn
authors.initials: K
authors.lastname: Volkening
authors.affiliation: Robarts Research Institute, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada.
authors.forename: Cheryl
authors.initials: C
authors.lastname: Leystra-Lantz
authors.affiliation: Robarts Research Institute, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada.
authors.forename: Wendy
authors.initials: W
authors.lastname: Strong
authors.affiliation: Graduate Program in Neuroscience, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada; Robarts Research Institute, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada; Department of Clinical Neurological Sciences, Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada. Electronic address: michael.strong@schulich.uwo.ca.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Strong
mesh_terms: D020816:Amino Acid Motifs; D000690:Amyotrophic Lateral Sclerosis / Q000235:genetics / Q000473:pathology / Q000628:therapy; D016923:Cell Death / Q000235:genetics; D002478:Cells, Cultured; D019295:Computational Biology; D055785:Gene Knockdown Techniques; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D057809:HEK293 Cells; D006801:Humans; D009454:Neurofibrils / Q000473:pathology*; D010766:Phosphorylation; D034741:RNA, Small Interfering / Q000235:genetics; D024801:Tauopathies / Q000235:genetics / Q000473:pathology / Q000628:therapy; D013912:Threonine / Q000378:metabolism; D016875:tau Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: C054369:MAPT protein, human; D034741:RNA, Small Interfering; D016875:tau Proteins; D013912:Threonine; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D038362:Glycogen Synthase Kinase 3
keywords: Amyotrophic lateral sclerosis; Glycogen synthase kinase 3 β; Microtubule-associated protein tau; Tauopathy