Tyrosine 394 is phosphorylated in Alzheimer's paired helical filament tau and in fetal tau with c-Abl as the candidate tyrosine kinase.
Tau is a major microtubule-associated protein of axons and is also the principal component of the paired helical filaments (PHFs) that comprise the neurofibrillary tangles found in Alzheimer's disease and other tauopathies. Besides phosphorylation of tau on serine and threonine residues in both normal tau and tau from neurofibrillary tangles, Tyr-18 was reported to be a site of phosphorylation by the Src-family kinase Fyn. We examined whether tyrosine residues other than Tyr-18 are phosphorylated in tau and whether other tyrosine kinases might phosphorylate tau. Using mass spectrometry, we positively identified phosphorylated Tyr-394 in PHF-tau from an Alzheimer brain and in human fetal brain tau. When wild-type human tau was transfected into fibroblasts or neuroblastoma cells, treatment with pervanadate caused tau to become phosphorylated on tyrosine by endogenous kinases. By replacing each of the five tyrosines in tau with phenylalanine, we identified Tyr-394 as the major site of tyrosine phosphorylation in tau. Tyrosine phosphorylation of tau was inhibited by PP2 (4-amino-5-(4-chlorophenyl-7-(t-butyl)pyrazolo[3,4-d]pyrimidine), which is known to inhibit Src-family kinases and c-Abl. Cotransfection of tau and kinases showed that Tyr-18 was the major site for Fyn phosphorylation, but Tyr-394 was the main residue for Abl. In vitro, Abl phosphorylated tau directly. Abl could be coprecipitated with tau and was present in pretangle neurons in brain sections from Alzheimer cases. These results show that phosphorylation of tau on Tyr-394 is a physiological event that is potentially part of a signal relay and suggest that Abl could have a pathogenic role in Alzheimer's disease.
Derkinderen
Pascal
P
Department of Neuroscience, Institute of Psychiatry, King's College London, London SE5 8AF, United Kingdom.
Scales
Timothy M E
TM
Hanger
Diane P
DP
Leung
Kit-Yi
KY
Byers
Helen L
HL
Ward
Malcolm A
MA
Lenz
Christof
C
Price
Caroline
C
Bird
Ian N
IN
Perera
Timothy
T
Kellie
Stuart
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Williamson
Ritchie
R
Noble
Wendy
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Van Etten
Richard A
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Leroy
Karelle
K
Brion
Jean-Pierre
JP
Reynolds
C Hugh
CH
Anderton
Brian H
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D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000378:metabolism*; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001921:Brain / Q000196:embryology; D001923:Brain Chemistry; D016466:CHO Cells; D019556:COS Cells; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D006224:Cricetinae; D003412:Cricetulus; D005260:Female; D005326:Fetal Proteins / Q000378:metabolism; D006801:Humans; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009419:Nerve Tissue Proteins / Q000502:physiology*; D009447:Neuroblastoma / Q000473:pathology; D016874:Neurofibrillary Tangles / Q000737:chemistry*; D009474:Neurons / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D019000:Phosphotyrosine / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D016315:Proto-Oncogene Proteins c-abl / Q000502:physiology*; D051076:Proto-Oncogene Proteins c-fyn / Q000502:physiology; D014162:Transfection; D014638:Vanadates / Q000494:pharmacology; D019061:src-Family Kinases / Q000378:metabolism; D016875:tau Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D005326:Fetal Proteins; D009419:Nerve Tissue Proteins; C076715:pervanadate; D016875:tau Proteins; D019000:Phosphotyrosine; D014638:Vanadates; D016315:Proto-Oncogene Proteins c-abl; D051076:Proto-Oncogene Proteins c-fyn; D019061:src-Family Kinases