title: Direct analysis of tau from PSP brain identifies new phosphorylation sites and a major fragment of N-terminally cleaved tau containing four microtubule-binding repeats.
abstract: Tangles containing hyperphosphorylated aggregates of insoluble tau are a pathological hallmark of progressive supranuclear palsy (PSP). Several phosphorylation sites on tau in PSP have been identified using phospho-specific antibodies, but no sites have been determined by direct sequencing due to the difficulty in enriching insoluble tau from PSP brain. We describe a new method to enrich insoluble PSP-tau and report eight phosphorylation sites [Ser46, Thr181, Ser202, Thr217, Thr231, Ser235, Ser396/Ser400 (one site) and Thr403/Ser404 (one site)] identified by mass spectrometry. We also describe a 35 kDa C-terminal tau fragment (tau35), lacking the N-terminus of tau but containing four microtubule-binding repeats (4R), that is present only in neurodegenerative disorders in which 4R tau is over-represented. Tau35 was readily detectable in PSP, corticobasal degeneration and 4R forms of fronto-temporal dementia with parkinsonism linked to chromosome 17, but was absent from control, Alzheimer's disease and Pick's disease brain. Our findings suggest the aggregatory characteristics of PSP-tau differ from those of insoluble tau in Alzheimer's disease brain and this might be related to the presence of a C-terminal cleavage product of tau.
authors.affiliation: MRC Centre for Neurodegeneration Research, King's College London, Institute of Psychiatry, London, UK. S.Wray@iop.kcl.ac.uk
authors.forename: Selina
authors.initials: S
authors.lastname: Wray
authors.forename: Malcolm
authors.initials: M
authors.lastname: Saxton
authors.forename: Brian H
authors.initials: BH
authors.lastname: Anderton
authors.forename: Diane P
authors.initials: DP
authors.lastname: Hanger
mesh_terms: D000595:Amino Acid Sequence; D001923:Brain Chemistry / Q000502:physiology; D006801:Humans; D008870:Microtubules / Q000737:chemistry / Q000378:metabolism* / Q000473:pathology; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000302:isolation & purification / Q000378:metabolism*; D010766:Phosphorylation / Q000502:physiology; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D012995:Solubility; D013494:Supranuclear Palsy, Progressive / Q000378:metabolism* / Q000473:pathology; D020079:Terminal Repeat Sequences / Q000502:physiology; D016875:tau Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D010446:Peptide Fragments; D016875:tau Proteins