CoChat
Sign Up
Cited by 723Alzheimer's disease research and treatmentsDementia and Cognitive Impairment ResearchAdvanced Proteomics Techniques and Applications

Tau PTM Profiles Identify Patient Heterogeneity and Stages of Alzheimer’s Disease

Open access
Wesseling, Hendrik, Mair, Waltraud, Kumar, Mukesh, Schlaffner, Christoph N., Tang, Shaojun, Beerepoot, Pieter, Fatou, Benoit, Guise, Amanda J. +15 more·2020·Cell
DOI 10.1016/j.cell.2020.10.029PMC PMC8168922
Open this paper in CoChat — free account

Abstract

SUMMARY To elucidate the role of Tau isoforms and post-translational modification (PTM) stoichiometry in Alzheimer’s disease (AD), we generated a high-resolution quantitative proteomics map of 95 PTMs on multiple isoforms of Tau isolated from postmortem human tissue from 49 AD and 42 control subjects. Although Tau PTM maps reveal heterogeneity across subjects, a subset of PTMs display high occupancy and frequency for AD, suggesting importance in disease. Unsupervised analyses indicate that PTMs occur in an ordered manner, leading to Tau aggregation. The processive addition and minimal set of PTMs associated with seeding activity was further defined by analysis of size-fractionated Tau. To summarize, features in the Tau protein critical for disease intervention at different stages of disease are identified, including enrichment of 0N and 4R isoforms, underrepresentation of the C terminus, an increase in negative charge in the proline-rich region (PRR), and a decrease in positive charge in the microtubule binding domain (MBD).

AI snapshot

Written from the paper’s full text.

TL;DR

This study used quantitative mass spectrometry to map tau post-translational modifications in postmortem brain from Alzheimer’s disease and control donors, finding heterogeneous but ordered modification patterns that track disease stage. It identifies isoform shifts and charge-related modifications linked to aggregation and seeding.

Key findings

Across 49 AD and 42 control subjects, 95 PTMs at 88 residues were mapped, including 55 phosphorylation, 17 ubiquitination, 19 acetylation, and 4 methylation sites; insoluble tau was about 100-fold higher in AD (~1,000 vs ~10 fmol/mg), while soluble tau was lower (~3,000 vs ~5,000 fmol/mg). Insoluble AD tau was enriched for 0N and 4R isoforms; N-terminal and C-terminal regions were underrepresented, proline-rich region phosphorylation was high, and microtubule-binding-domain acetylation/ubiquitination increased with aggregate size. Unsupervised clustering separated subjects into groups reflecting Braak stage and PTM burden, and a classifier trained on cohort 1 predicted AD pathology in cohort 2 with >0.92 accuracy. Size-fractionated tau showed seeding-competent high-molecular-weight/insoluble species had microtubule-binding-domain modifications and 20 phosphosites in the high-molecular-weight fraction, while seeding-incompetent low-molecular-weight/soluble species were N-terminally enriched and had fewer proline-rich-region phosphosites.

Methods

Postmortem BA39 angular gyrus from 49 AD and 42 matched controls was analyzed, plus BA46 frontal gyrus in 9 controls and 10 AD subjects; high- and low-molecular-weight tau fractions came from 4 AD and 4 control subjects. FLEXITau targeted mass spectrometry quantified absolute tau and isoform-specific peptides, while data-dependent LC-MS/MS mapped PTMs; sarkosyl solubility and size-exclusion/MC1 fractionation separated tau species. Analyses included PCA, hierarchical clustering, PLS-DA, Spearman correlation, and a stochastic gradient descent classifier; data were deposited in ProteomeXchange.

Limitations

Stated: using top-ranked PTMs as biomarkers requires an adequately powered study with suitable specimens, and high-molecular-weight fraction PTM patterns showed patient-to-patient variability. Stated/evident: the postmortem cross-sectional design cannot directly prove temporal order or causality of PTM progression, and some controls had early AD-like PTMs, complicating group boundaries. Evident: some analyses rely on small subsets (BA46 n=19; high-/low-molecular-weight n=8), and stoichiometry for some microtubule-binding-domain sites was around 50%, so not every tau molecule carries those modifications.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1016/j.cell.2020.10.029

Cites

78 of 78 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 34 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    The analysis extended phosphorylation sites on pathological insoluble Tau to 55 in BA39 and 43 in BA46.

    “Our analysis extended this to 55 phosphorylation sites on pathological insoluble Tau in BA39 and 43 phosphosites in B46 (Figure S2C).”
    Quote in the paperNot a substantial claim
  • Findingown data

    Median concentration of pathological insoluble Tau in BA39 is about 100-fold higher in AD (~1,000 fmol/mg) than controls (~10 fmol/mg).

    “The median concentrations of pathological insoluble Tau in BA39 were 100-fold higher in AD (~1,000 fmol/mg fresh weight of tissue) compared with controls (~10 fmol/mg fresh weight of tissue) (Figure 1B).”
    Quote in the paperSubstantial claim
  • Findingown data

    In soluble Tau, the most abundant species are 1N and 4R isoforms.

    “Interestingly, in soluble Tau, the most abundant species are the 1N and 4R isoforms”
    Quote in the paperNot a substantial claim
  • Findingown data

    Features include underrepresentation of the C terminus.

    “underrepresentation of the C terminus”
    Quote in the paperNot a substantial claim
  • Findingown data

    The highest-frequency PTMs, isoform distributions, and quantitative profiles of the BA46 region are shared between the two brain regions.

    “The data and subsequent analyses showed that that the highest-frequency PTMs, isoform distributions, and quantitative profiles of the BA46 region are shared between the two brain regions”
    Quote in the paperNot a substantial claim
  • May combine two claims. 41
  • Classified as probably not a substantial claim. 27
  • The quote only partly states this claim. 1

  • May combine two claims.

    Findingown data

    Cluster d contains 10 symptomatic patients with late-stage AD pathology Braak IV-VI and 16 asymptomatic controls at Braak 0-II.

    “Cluster d contains 10 symptomatic patients with late stage AD pathology Braak IV-VI and 16 asymptomatic controls at Braak 0–II.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    ANOVA showed higher Tau and Aβ levels in clusters with higher Braak stage and increased level of Tau PTMs.

    “ANOVA analysis showed higher Tau and Ab levels in clusters with a higher Braak stage and increased level of Tau PTMs (Figure 2B).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The analysis identified 95 distinct PTMs on 88 amino acid residues across all samples and fractions, with 96% cumulative sequence coverage from detected modified and unmodified 2N4R Tau peptides.

    “We identified 95 distinct PTMs on 88 amino acid residues across all samples and fractions, with a cumulative sequence coverage of 96% from detected modified and unmodified 2N4R Tau peptides (Figure 1E).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Some of the 88 modification sites carry a single PTM type, while others can carry multiple types, such as K311 being ubiquitinated or acetylated.

    “Some of the 88 sites of modification mapped are modified by a single type of PTM; however, others can carry multiple types of modifications, such as K311, which can be ubiquitinated or acetylated.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    17 ubiquitin sites are specific to pathological Tau, with 14 in BA46.

    “In this study, we show that 17 ubiquitin sites are specific to pathological Tau (14 in BA46; Figure S2C).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    A large percentage of AD patients cluster into two major groups (b and c), whereas controls fall into two clusters (a and d).

    “A large percentage of AD patients cluster into two major groups (Figure 2A, b and c), whereas the controls fall into two clusters (Figure 2A, a and d).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In the insoluble fraction, 1N isoform is significantly depleted and 0N isoform is enriched.

    “Instead, the 1N isoform is depleted significantly, and the 0N isoform is enriched in the insoluble fraction.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    FLEXITau quantified 24 Tau peptides, some isoform specific, achieving 61% sequence coverage for 2N4R Tau.

    “FLEXITau quantified a total of 24 Tau peptides; of these, some were isoform specific, achieving a total sequence coverage of 61% for the 2N4R Tau isoform (Figure 1D).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    High frequency acetylation occurs in the R4 region, including K353, K369, K370, and K375, whereas ubiquitination occurs in R1-R3.

    “A high frequency of acetylation occurs in the R4 region, including the sites K353, K369, K370, and K375, whereas ubiquitination occurs in R1–R3.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    In insoluble Tau, 0N and 1N isoforms are significantly enriched compared with 2N, and 4R is significantly enriched compared with 3R.

    “in the insoluble fraction containing pathologic Tau, 0N and 1N Tau were enriched significantly compared with the 2N isoform, and the 4R isoform is enriched significantly compared with the 3R isoform.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The Braak stage of cluster b is V, and the Braak stage of cluster c is VI.

    “The Braak stage of cluster b is V, whereas the Braak stage of cluster c is VI”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Nineteen distinct acetylation sites were mapped in BA39 and 18 in BA46.

    “Nineteen distinct acetylation sites were mapped in BA39 and 18 in BA46.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Clusters b and c display many of the same PTMs, but cluster c has higher frequency of several PTMs, including T175, S237, and K281 (and S113, S191, T205).

    “Clusters b and c display many of the same PTMs; however, in cluster c, we observe a higher frequency of several PTMs, including T175, S237, and K281 (and S113, S191, and T205, which are difficult to observe at lower stoichiometry, particularly because S113 is a phosphosite found on a 0N Tau peptide).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    These MBD PTMs include phosphorylation at adjacent sites S262 and S263, acetylation at K311, K353, and K369, and ubiquitination at K259, K267, K311, and K317.

    “These PTMs include phosphorylation occurring at adjacent sites (S262 and S263), acetylation (K311, K353, and K369), and ubiquitination (K259, K267, K311, and K317).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The number of PTMs and the occupancy of PTM sites increase at different stages of disease.

    “These data indicate that there is an increase in the number of PTMs and the occupancy of these PTM sites observed at different stages of disease”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Analysis of pathological Tau from 91 subjects (49 AD and 42 control) identified 95 PTMs at 88 amino acid residues, comprising 55 phosphosites, 17 ubiquitination sites, 19 acetylation sites, and 4 methylation sites.

    “Our analysis of pathological Tau from 91 subjects (49 AD and 42 control subjects) cumulatively identifies 95 PTMs at 88 aa residues. We mapped 55 phosphosites, 17 ubiquitination sites, 19 acetylation sites, and four methylation sites along the length of the Tau protein.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Seeding-incompetent AD and control Tau sarkosyl-soluble fractions show no differences and are both enriched in N-terminal regions.

    “The seeding-incompetent AD and control Tau sarkosyl-soluble fractions show no differences; both are enriched in the N-terminal regions (Figure 4C).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The unmodified C-terminal peptide is found with low abundance in AD compared to all controls, but one control cluster has a completely unmodified C terminus and another control cluster shows some processing.

    “Although the unmodified C-terminal peptide is found with low abundance in AD compared to all controls, there is a control cluster where the C terminus is completely unmodified (Figure 3A) and the other control cluster shows some processing.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Unsupervised analyses based on presence or absence of PTMs clustered subjects into 4 major groups with specific PTM combinations in each group.

    “Unsupervised analyses based on the presence or absence of PTMs clustered the subjects into 4 major groups and revealed that there were specific combinations of PTMs in each of these groups.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    As Tau aggregate size increases, the PRR accumulates phosphosites and the MBD accumulates acetylation and ubiquitination.

    “the PRR appears to accumulate phosphosites and the MBD appears to accumulate acetylation and ubiquitination with increasing size of Tau aggregates.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    HMW Tau has 20 phosphosites (6 in the N terminus, 10 in the PRR, 4 in the C-terminal region) and 3 acetylation and 4 ubiquitin sites in the MBD.

    “HMW Tau, which is thought to be oligomeric Tau, displays 20 phosphosites (6 in the N terminus, 10 in the PRR, and 4 in the C-terminal region) as well as 3 acetylation and 4 ubiquitin sites in the MBD.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    LMW Tau and sarkosyl-soluble Tau have similar PTM patterns, with six phosphorylations in the PRR, including T181, S199, S202, and T231, consistently observed in both fractions.

    “LMW Tau shows a similar modification pattern to Tau as the sarkosyl-soluble fraction, with 6 phosphorylations (T181, S199, S202, and T231) in the PRR being consistently observed sites in LMW and sarkosyl-soluble fractions.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The N-specific region is largely underrepresented in AD, as is the C terminus.

    “The N-specific region is largely underrepresented (45–67, 68–87, and 88–126), as is the C terminus in AD.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Comparative analysis of HMW Tau and larger fibrillized insoluble Tau shows a similar pattern, but the MBD is even more enriched in insoluble Tau and peptide 260-267 is underrepresented, indicating higher phosphorylation stoichiometry of S262 and T263.

    “Comparative analysis of the two seeding-competent fractions, HMW Tau and the larger, fibrillized, insoluble Tau, shows a similar pattern; however, the MBD is even more enriched in the insoluble Tau fraction, and the peptide 260–267 is underrepresented, indicating a higher phosphorylation stoichiometry of this peptide (S262 and T263).”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    These sites include three KXGS motifs.

    “These sites include three KXGS motifs”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Acetylation and ubiquitination are observed in the MBD of HMW Tau.

    “Although acetylation and ubiquitination are observed in the MBD of HMW Tau”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Patient frequency of these PTMs is high, but their stoichiometry is about 50%, so every second Tau molecule in a fibril is modified.

    “The patient frequency of these PTMs is high; however, the stoichiometry of these sites is ~50%; thus, every second Tau molecule in a fibril is modified.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The increase in these modifications correlates positively with increasing polymer length and increased abundance of pathological Tau associated with disease progression.

    “Moreover, the increase in these modifications correlates positively with increasing polymer length and increased abundance of pathological Tau associated with disease progression.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    FLEXITau provides absolute quantification and unbiased stoichiometric information of Tau PTMs from the N to the C terminus.

    “we previously developed a targeted, high-throughput quantitative mass spectrometry (MS) method called FLEXITau (full-length expressed stable isotope-labeled Tau) (Mair et al., 2016), which provides absolute quantification and unbiased stoichiometric information of Tau PTMs from the N to the C terminus.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Mair et al., 2016

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Tau forms intracellular neurofibrillary tangles.

    “Tau forms intracellular neurofibrillary tangles (NFTs) (Grundke-Iqbal et al., 1986; Kosik et al., 1986; Wood et al., 1986)”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites Grundke-Iqbal et al., 1986

      Not checked in the free run.

    • cites Kosik et al., 1986

      Not checked in the free run.

    • cites Wood et al., 1986

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Tens of possible PTM sites have been described for Tau in in vitro, in vivo AD mouse models, and postmortem human studies.

    “Tens of possible PTM sites have been described for Tau in studies involving in vitro (Hanger et al., 2007; Martin et al., 2013a, 2013b) and in vivo AD mouse models (Morris et al., 2015; Tramutola et al., 2018) and in postmortem human studies (Hanger et al., 2007; Min et al., 2015).”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites Hanger et al., 2007

      Not checked in the free run.

    • cites Martin et al., 2013a

      Not checked in the free run.

    • cites Morris et al., 2015 source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Premisecitation

    Neurofibrillary aggregates are subject to a wide range of PTMs besides phosphorylation.

    “Besides phosphorylation, the neurofibrillary aggregates are also subject to a wide range of other PTMs (Hanger et al., 2007)”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Hanger et al., 2007

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Aβ forms extracellular plaques.

    “Aβ forms extracellular plaques (Glenner and Wong, 1984; Masters et al., 1985)”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Glenner and Wong, 1984

      Not checked in the free run.

    • cites Masters et al., 1985

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    During AD progression, pathological neurofibrillary Tau aggregates accumulate starting in the entorhinal cortex and spread through connected pathways to cortical areas.

    “pathological neurofibrillary Tau aggregates show a pattern of accumulation that starts in the entorhinal cortex and spreads through connected pathways to cortical areas (Jucker and Walker, 2013)”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Jucker and Walker, 2013 source

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data

    The majority of subjects in cluster d are listed as controls, and these PTMs are likely the earliest signs of pathology.

    “The majority of subjects in d are listed as control subjects, and these PTMs are likely to be the earliest signs of pathology.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisenone given

    Antibody-based approaches cannot accurately measure quantitative changes or determine PTM stoichiometry.

    “they cannot accurately measure quantitative changes or determine PTM stoichiometry.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Dominantly inherited Tau mutations lead to frontotemporal dementia.

    “The discovery of dominantly inherited Tau mutations leading to frontotemporal dementia (FTD) (Poorkaj et al., 1998; Spillantini et al., 1998)”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Poorkaj et al., 1998 source

      Not checked in the free run.

    • cites Spillantini et al., 1998 source

      Not checked in the free run.

  • The quote only partly states this claim.

    Interpretationown data

    The presence of these phosphorylation sites in 20-40% of controls suggests early disease in a few controls.

    “suggesting that early disease is observed in a few controls.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Premisecitation

    Brain lysates seed Tau aggregation when high-molecular-weight oligomeric hyperphosphorylated (AT8 and AT100) Tau species are present.

    “brain lysates seed Tau aggregation when high-molecular-weight oligomeric hyperphosphorylated (AT8 and AT100) Tau species are present (Takeda et al., 2015; Jackson et al., 2016)”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Takeda et al., 2015 source

      Not checked in the free run.

    • cites Jackson et al., 2016

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Premisecitation

    Combinations of PTMs regulate and fine-tune protein conformation and activity.

    “Combinations of such PTMs are responsible for regulating and fine-tuning protein conformation and activity (Aebersold et al., 2018; Soria et al., 2014)”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Aebersold et al., 2018 source

      Not checked in the free run.

    • cites Soria et al., 2014

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Tau propagation involves production of a Tau seed followed by uptake of seed-competent Tau into connected cells.

    “This encompasses a cycle that involves production of a Tau seed followed by uptake of seed-competent Tau into connected cells (Clavaguera et al., 2013)”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Clavaguera et al., 2013

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    Modification at the C terminus is an early event during aging and AD pathology and can most likely be attributed to caspase-3 and -6 cleavage at D418 and D421.

    “This suggests that the modification at the C terminus is an early event during aging and AD pathology and can most likely be attributed to caspase-3 and −6 cleavage at D418 and D421.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The MBD forms the core region of Tau filaments.

    “which has been shown to form the core region of the Tau filaments (Fitzpatrick et al., 2017).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Fitzpatrick et al., 2017

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    KXGS motifs are known to regulate neurite extension and binding of Tau to microtubules.

    “which are known to regulate neurite extension and binding of Tau to microtubules (Biernat et al., 1993; Biernat and Mandelkow, 1999).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Biernat et al., 1993

      Not checked in the free run.

    • cites Biernat and Mandelkow, 1999

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data

    Early intervention may need different therapeutic agents than late-stage AD because there are distinct differences in PTM profiles associated with each stage of disease.

    “Importantly, these data suggest that early intervention may need different therapeutic agents than late-stage AD because there are distinct differences in PTM profiles associated with each stage of disease.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationown data

    Increased phosphorylation of Tau may neutralize charge in the MBD to promote aggregation.

    “This increase in phosphorylation of Tau may be involved in neutralizing the charge in the MBD domain to promote aggregation”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    The sets of PTMs were largely reflective of disease progression and could be associated with disease stages.

    “The sets of PTMs were largely reflective of disease progression and therefore could be associated with disease stages.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    The above results indicate processivity and an order in which PTMs occur in the fibrillization process.

    “The above results from sarkosyl-insoluble (fibrillized) Tau from AD and control subjects indicate that there is processivity and an order in which PTMs occur in the fibrillization process.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The extensive interplay observation is partially consistent with recent Tau PTM mapping results in mice.

    “an observation partially consistent with recent Tau PTM mapping results in mice (Morris et al., 2015; Table S5).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Morris et al., 2015 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductnone given

    Samples were run in randomized order to ensure no bias in acquisition, with three technical replicates per sample.

    “To ensure no bias in acquisition, samples were run in randomized order (three technical replicates per sample).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Every MS/MS spectrum of an identified post-translationally modified peptide was subjected to manual verification.

    “In addition, all MS/MS spectra of identified post-translationally modified peptides were subjected to manual verification.”
    • Also stated in: § Preparation and MS analysis of MC1-isolated Tau · plain
      “Spectra for identified modified peptides were manually validated.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    The 0N and 4R version, when phosphorylated, is no longer disordered and can adopt a structure capable of fibril formation.

    “These data suggest that the 0N and 4R version, when phosphorylated, is no longer disordered and can adopt a structure capable of fibril formation.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    All MS/MS spectra of identified post-translationally modified peptides were manually verified.

    “In addition, all MS/MS spectra of identified post-translationally modified peptides were subjected to manual verification.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    All peptide transitions were evaluated for variability, similarity between y-ion ratios, elution times, and interfering signals by manual analysis.

    “All peptide transitions were evaluated for variability, similarity between y-ion ratios, elution times, and interfering signals by manual analysis.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    Peptides were considered quantifiable if transitions had signal-to-noise >3 and at least three light and three heavy high-quality SRM transitions were observed.

    “Peptides were considered ‘quantifiable’ if the peptide transitions had a signal-to-noise of > 3 and at least three light and three heavy high-quality SRM transitions were observed.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationnone given

    MBD lysine residues would be positively charged at physiological pH and experience repulsive electrostatic forces that prevent beta sheet fibril formation.

    “which would be charged positively at physiological pH and experience repulsive electrostatic forces, preventing formation of a b sheet fibril structure.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Tau contains 19 lysine residues in its microtubule-binding domain.

  • Classified as probably not a substantial claim.

    Interpretationreasoning

    Increased phosphorylation in the PRR results in accumulation of negative charges that could neutralize the positive charge in the MBD.

    “Increased phosphorylation in the PRR results in accumulation of negative charges, which, we postulate, could neutralize the positive charge in the MBD”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Study design and conductown data

    The false discovery rate was controlled at 1% at both the peptide and protein level, and this threshold was established by searching a decoy reverse database.

    “False discovery rate (FDR) was set to 1% on peptide and protein levels with a minimum length of seven amino acids and was determined by searching a reverse database.”
    • Also stated in: § Preparation and MS analysis of MC1-isolated Tau · plain
      “False discovery rate (FDR) was set to 1% on peptide and protein level and was determined by searching a reverse database.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The samples analyzed by mass spectrometry were randomized.

    “Randomized samples (SEC fractions 2,3,4 and 14,16,18 for 4 AD and 4 control human brain samples) were analyzed in duplicates using a Q Exactive mass spectrometer”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    The samples were analyzed in duplicate.

    “Randomized samples (SEC fractions 2,3,4 and 14,16,18 for 4 AD and 4 control human brain samples) were analyzed in duplicates using a Q Exactive mass spectrometer”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    An 85% confidence cutoff was applied to all modified peptides.

    “A cutoff of 85% confidence was employed for all modified peptides.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    Peak boundaries were manually inspected and reassigned as needed to ensure correct peak detection and accurate integration.

    “Peak boundaries were manually inspected and reassigned as needed to ensure correct peak detection and accurate integration.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    A cutoff of 85% confidence was employed for all modified peptides.

    “A cutoff of 85% confidence was employed for all modified peptides.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    The data support a processive model in which 0N and 4R are predisposed to aggregation, C terminus cleavage enables fibrillization, and subsequent phosphorylation in the PRR and acetylation/ubiquitination in the MBD remove electrostatic repulsion of positively charged lysines, promoting Tau fibrilization.

    “Our data support a processive model (Figure 5C) where 0N and 4R are predisposed to aggregation, cleavage of the C terminus enables fibrillization, followed by phosphorylation in the PRR domain and acetylation and ubiquitination in the MBD, which remove electrostatic repulsion of positively charged lysine residues in this region, promoting Tau fibrilization.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    Western blot analysis with Tau13, Tau46, HT7 and DAKO antibodies confirmed that SEC fractions 3 and 4 are enriched for Tau.

    “Western Blot analysis using Tau13, Tau46, HT7 and DAKO antibodies confirmed that the fraction 3 and 4 are enriched for Tau (data not shown).”
    Quote in the paperNot a substantial claim
65 of 65

  • The authors state this as an assumption.

    A qualitative and quantitative approach using a large cohort of human AD subjects had not been performed before this study.

    “To our knowledge, a qualitative and quantitative approach using a large cohort of human AD subjects has not been performed.”

  • The authors state this as an assumption.

    The minimum set of PTMs important for oligomer formation and Tau aggregation is not known.

    “Furthermore, the minimum set of PTMs important for oligomer formation and Tau aggregation is not known.”

  • The authors state this as an assumption.

    Which PTMs occur on Tau seeds that can potentiate further aggregation is not known.

    “Finally, it is not known which PTMs occur on Tau seeds that can potentiate further aggregation.”

  • The paper relies on this without support.

    Tau contains 19 lysine residues in its microtubule-binding domain.

    “Tau has 19 lysine residues in the MBD”

  • The paper relies on this without support.

    The disordered regions of Tau include the N terminus and the proline-rich region.

    “The disordered regions of Tau span the N terminus and PRR.”

  • The paper relies on this without support.

    HMW Tau is oligomeric Tau.

    “HMW Tau, which is thought to be oligomeric Tau”
6 of 6

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Cases with most marked propagation potential had the fastest clinical course and characteristic patterns of post-translational modifications.

    “In examining the clinical records, we found that those cases with the most marked propagation potential also had the fastest clinical course and had characteristic patterns of post-translational modifications (10, 11).”

    From All the Tau We Cannot See (2023) · cites this paper as [11]

  • Tau is often measured with antibodies for phosphorylation at threonine 181 and total-tau, but at least 95 post-translational modifications have been discovered on tau, with potentially hundreds of proteoforms from combinations.

    “For example, the microtubule-associated protein tau is often measured using antibodies that represent phosphorylation at threonine 181 and one that measures so called “total-tau”. However, at least 95 post-translational modifications have been discovered on tau with potentially many 100s of possible proteoforms resulting from the combinations.(16)”

    From Putting humpty dumpty back together again: what does protein quantification mean in bottom-up proteomics? (2022) · cites this paper as [16]

  • Specific tau phosphosites may be better indicators of disease progression, which emphasizes the importance of distinguishing pTau isoforms and proteoforms.

    “Additional studies indicate that specific tau phosphosites may be better indicators of disease progression, emphasizing the importance of distinguishing between different pTau isoforms and proteoforms.(15,16)”

    From Putting humpty dumpty back together again: what does protein quantification mean in bottom-up proteomics? (2022) · cites this paper as [16]

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Acetylation is both unique to seeding-positive Tau and present in seeding-incompetent Tau

    Major

    One passage says acetylation is unique to seeding-positive Tau relative to the seeding-negative fractions. The discussion instead says acetylation also occurs in seeding-incompetent Tau.

  • Residue 263 is identified as both serine and threonine

    Minor

    The results identify phosphorylation at S263 in one passage and T263 in another. The same numbered residue cannot have both identities in the Tau sequence being described.

2 of 2

Cites

Flagged first, then by citations

Research works printed but not linked: 2

  1. Lê, 2008, FactoMineR: A Package for Multivariate Analysis, J. Stat. Softw., 25
  2. Lovestone, 1997, The phosphorylation of tau: a critical stage in neurodevelopment and neurodegenerative processes, Neuroscience, 78, 309

Cited by

Sorted by citations

Related

Authors
Wesseling, H., Mair, W., Kumar, M., Schlaffner, C. N., Tang, S., Beerepoot, P., Fatou, B., Guise, A. J., Cheng, L., Takeda, S., Muntel, J., Rotunno, M. S., Dujardin, S., Davies, P., Kosik, K. S., Miller, B. L., Berretta, S., Hedreen, J. C., Grinberg, L. T., Seeley, W. W., Hyman, B. T., Steen, H., & Steen, J. A.
Affiliations
  • Boston Children's Hospital (US)
  • Harvard University (US)
  • Feinstein Institute for Medical Research (US)
  • University of California, Santa Barbara (US)
  • University of California, San Francisco (US)
Corresponding author
Steen, Judith A.
ORCID
Venue
Cell
Publisher
Elsevier BV
Published
2020-12
Volume
183
Issue
6
Pages
1699-1713.e13
ISSN
0092-8674 (ISSN-L)
DOI
10.1016/j.cell.2020.10.029
PMC
PMC8168922
OpenAlex
W3102160053
Semantic Scholar
eb7657dfe7b98f7376299bf9d45805d3dc70eb6d
Cited by
688
References
78
Citations by year
2026: 104 · 2025: 132 · 2024: 140 · 2023: 112 · 2022: 109 · 2021: 88 · 2020: 2
FWCI
47.08
Type
journal article
Language
en
Open access
Licence
Locations
  • Cell (publishedVersion)
  • PubMed (publishedVersion)
  • PubMed Central (acceptedVersion)
  • Rare & Special e-Zone (The Hong Kong University of Science and Technology) (submittedVersion)
  • eScholarship (California Digital Library) (submittedVersion)
Funders
  • National Institutes of Health
  • Tau Consortium
Topics
  • Health Sciences › Medicine › Physiology › Alzheimer's disease research and treatments
  • Health Sciences › Medicine › Psychiatry and Mental health › Dementia and Cognitive Impairment Research
  • Physical Sciences › Chemistry › Spectroscopy › Advanced Proteomics Techniques and Applications
Keywords
Alzheimer's disease, tau protein, post-translational modification, tau isoforms, tau aggregation, seeding activity, patient heterogeneity, disease staging, proline-rich region, microtubule-binding domain, postmortem brain, quantitative proteomics
MeSH terms
Alzheimer Disease, Humans, Protein Processing, Post-Translational, Cohort Studies, Case-Control Studies, tau Proteins, Disease Progression, Protein Isoforms, Principal Component Analysis

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-07.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-07.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review