title: Comprehensive Quantitative Profiling of Tau and Phosphorylated Tau Peptides in Cerebrospinal Fluid by Mass Spectrometry Provides New Biomarker Candidates.
abstract: Aberrant tau phosphorylation is a hallmark in Alzheimer's disease (AD), believed to promote formation of paired helical filaments, the main constituent of neurofibrillary tangles in the brain. While cerebrospinal fluid (CSF) levels of total tau and tau phosphorylated at threonine residue 181 (pThr181) are established core biomarkers for AD, the value of alternative phosphorylation sites, which may have more direct relevance to pathology, for early diagnosis is not yet known, largely due to their low levels in CSF and lack of standardized detection methods. To overcome sensitivity limitations for analysis of phosphorylated tau in CSF, we have applied an innovative mass spectrometry (MS) workflow, TMTcalibratortrademark, to enrich and enhance the detection of phosphoproteome components of AD brain tissue in CSF, and enable the quantitation of these analytes. We aimed to identify which tau species present in the AD brain are also detectable in CSF and which, if any, are differentially regulated with disease. Over 75% coverage of full-length (2N4R) tau was detected in the CSF with 47 phosphopeptides covering 31 different phosphorylation sites. Of these, 11 phosphopeptides were upregulated by at least 40%, along with an overall increase in tau levels in the CSF of AD patients relative to controls. Use of the TMTcalibratortrademark workflow dramatically improved our ability to detect tau-derived peptides that are directly related to human AD pathology. Further validation of regulated tau peptides as early biomarkers of AD is warranted and is currently being undertaken.
authors.affiliation: Proteome Sciences plc, South Wing Laboratory, Institute of Psychiatry, De Crespigny Park, London, UK.
authors.forename: Claire L
authors.initials: CL
authors.lastname: Russell
authors.affiliation: Proteome Sciences plc, South Wing Laboratory, Institute of Psychiatry, De Crespigny Park, London, UK.
authors.forename: Vikram
authors.initials: V
authors.lastname: Mitra
authors.affiliation: Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, The Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden.
authors.forename: Karl
authors.initials: K
authors.lastname: Hansson
authors.affiliation: Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, The Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden.|Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden.
authors.forename: Kaj
authors.initials: K
authors.lastname: Blennow
authors.affiliation: Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, The Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden.|Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Gobom
authors.affiliation: Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, The Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden.|Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden.|Department of Molecular Neuroscience, University College London, Institute of Neurology, Queen Square, London, UK.
authors.forename: Henrik
authors.initials: H
authors.lastname: Zetterberg
authors.affiliation: Institute of Biomedicine, University of Eastern Finland, Kuopio, Finland.|Department of Neurology, Kuopio University Hospital, Kuopio, Finland.
authors.forename: Mikko
authors.initials: M
authors.lastname: Hiltunen
authors.affiliation: Proteome Sciences plc, South Wing Laboratory, Institute of Psychiatry, De Crespigny Park, London, UK.
authors.forename: Malcolm
authors.initials: M
authors.lastname: Ward
authors.affiliation: Proteome Sciences plc, South Wing Laboratory, Institute of Psychiatry, De Crespigny Park, London, UK.
authors.forename: Ian
authors.initials: I
authors.lastname: Pike
mesh_terms: D000544:Alzheimer Disease / Q000134:cerebrospinal fluid*; D016229:Amyloid beta-Peptides / Q000134:cerebrospinal fluid; D015415:Biomarkers / Q000134:cerebrospinal fluid; D001923:Brain Chemistry; D015331:Cohort Studies; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D013058:Mass Spectrometry; D010446:Peptide Fragments / Q000134:cerebrospinal fluid; D010766:Phosphorylation; D016875:tau Proteins / Q000134:cerebrospinal fluid* / Q000737:chemistry
chemical_list: D016229:Amyloid beta-Peptides; D015415:Biomarkers; C054369:MAPT protein, human; D010446:Peptide Fragments; C075222:amyloid beta-protein (1-42); D016875:tau Proteins
keywords: Alzheimer’s disease; biomarkers; cerebrospinal fluid; mass spectrometry; neurodegenerative disease; phosphorylation; post translational modifications; tau