title: Proteomic analysis of neurofibrillary tangles in Alzheimer disease identifies GAPDH as a detergent-insoluble paired helical filament tau binding protein.
abstract: We performed proteomic analysis of neurofibrillary tangles (NFTs) obtained by laser capture microdissection from pyramidal neurons in hippocampal sector CA1 in patients with Alzheimer disease (AD) using liquid chromatography (LC)-mass spectrometry (MS)/MS. We discovered a total of 155 proteins in laser captured NFT's, 72 of which were identified by multiple unique peptides. Of these 72 proteins, 63 had previously unknown association with NFTs; one of these was glyceraldehyde-3-phosphate dehydrogenase (GAPDH). We validated by immunohistochemistry that GAPDH co-localized with the majority of NFTs as well as plaque-like structures in AD brain and was co-immunoprecipitated by antibodies to abnormal forms of tau in AD, but not tau from AD temporal cortex. Characterization of GAPDH showed that it, along with phosphorylated tau and Abeta peptides, was present in detergent-insoluble fractions from AD temporal cortex but not from age-matched controls. These data are the first proteomic investigation of NFTs. Moreover, our results validate this approach by demonstrating that GAPDH, a glycolytic and microtubule binding protein, not only co-localized to NFTs and immunoprecipitated with PHF-tau, but also is one of the few proteins known to undergo conversion to a detergent-insoluble form in AD.
authors.affiliation: Department of Pathology, Division of Neuropathology, University of Washington, Seattle, Washington 98105, USA.
authors.forename: Qin
authors.initials: Q
authors.lastname: Wang
authors.forename: Randall L
authors.initials: RL
authors.lastname: Woltjer
authors.forename: P J
authors.initials: PJ
authors.lastname: Cimino
authors.forename: Catherine
authors.initials: C
authors.lastname: Pan
authors.forename: Kathleen S
authors.initials: KS
authors.lastname: Montine
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Montine
mesh_terms: D000544:Alzheimer Disease / Q000201:enzymology*; D015153:Blotting, Western; D002853:Chromatography, Liquid; D003902:Detergents; D024601:Glyceraldehyde 3-Phosphate Dehydrogenase (NADP+) / Q000032:analysis* / Q000737:chemistry; D006624:Hippocampus / Q000737:chemistry; D006801:Humans; D007150:Immunohistochemistry; D013058:Mass Spectrometry; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D016874:Neurofibrillary Tangles / Q000201:enzymology*; D017433:Protein Structure, Secondary; D040901:Proteomics; D012995:Solubility; D013702:Temporal Lobe / Q000737:chemistry; D014357:Trypsin / Q000378:metabolism; D016875:tau Proteins
chemical_list: D003902:Detergents; C054369:MAPT protein, human; D009419:Nerve Tissue Proteins; D016875:tau Proteins; D024601:Glyceraldehyde 3-Phosphate Dehydrogenase (NADP+); D014357:Trypsin