title: Extensive deamidation at asparagine residue 279 accounts for weak immunoreactivity of tau with RD4 antibody in Alzheimer's disease brain.
abstract: BACKGROUND
  Intracytoplasmic inclusions composed of filamentous tau proteins are defining characteristics of neurodegenerative tauopathies, but it remains unclear why different tau isoforms accumulate in different diseases and how they induce abnormal filamentous structures and pathologies. Two tau isoform-specific antibodies, RD3 and RD4, are widely used for immunohistochemical and biochemical studies of tau species in diseased brains.
  
  
  RESULTS
  Here, we show that extensive irreversible post-translational deamidation takes place at asparagine residue 279 (N279) in the RD4 epitope of tau in Alzheimer's disease (AD), but not corticobasal degeneration (CBD) or progressive supranuclear palsy (PSP), and this modification abrogates the immunoreactivity to RD4. An antiserum raised against deamidated RD4 peptide specifically recognized 4R tau isoforms, regardless of deamidation, and strongly stained tau in AD brain. We also found that mutant tau with N279D substitution showed reduced ability to bind to microtubules and to promote microtubule assembly.
  
  
  CONCLUSIONS
  The biochemical and structural differences of tau in AD from that in 4R tauopathies found in this study may therefore have implications for prion-like propagation of tau.
authors.affiliation: Department of Neuropathology and Cell Biology, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 156-8506, Japan. hasegawa-ms@igakuken.or.jp.
authors.forename: Ayaho
authors.initials: A
authors.lastname: Dan
authors.forename: Muneaki
authors.initials: M
authors.lastname: Takahashi
authors.forename: Masami
authors.initials: M
authors.lastname: Masuda-Suzukake
authors.forename: Fuyuki
authors.initials: F
authors.lastname: Kametani
authors.forename: Takashi
authors.initials: T
authors.lastname: Nonaka
authors.forename: Hiromi
authors.initials: H
authors.lastname: Kondo
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Akiyama
authors.forename: Takao
authors.initials: T
authors.lastname: Arai
authors.forename: David M A
authors.initials: DM
authors.lastname: Mann
authors.forename: Yuko
authors.initials: Y
authors.lastname: Saito
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Hatsuta
authors.forename: Shigeo
authors.initials: S
authors.lastname: Murayama
authors.forename: Masato
authors.initials: M
authors.lastname: Hasegawa
mesh_terms: D000544:Alzheimer Disease / Q000378:metabolism*; D000906:Antibodies / Q000235:genetics / Q000276:immunology*; D001216:Asparagine; D001921:Brain / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D008870:Microtubules / Q000378:metabolism; D009154:Mutation; D020033:Protein Isoforms / Q000235:genetics / Q000276:immunology; D011499:Protein Processing, Post-Translational; D011994:Recombinant Proteins / Q000378:metabolism; D013494:Supranuclear Palsy, Progressive / Q000378:metabolism; D016875:tau Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*
chemical_list: D000906:Antibodies; C054369:MAPT protein, human; D020033:Protein Isoforms; D011994:Recombinant Proteins; D016875:tau Proteins; D001216:Asparagine