Assembly of tau in transgenic animals expressing P301L tau: alteration of phosphorylation and solubility.
Transgenic mice (JNPL3), which develop neurofibrillary degeneration and express four-repeat human tau with P301L missense mutation, were characterized biochemically to determine whether the development of aggregated tau from soluble tau involves an intermediate stage. Homogenates from mice of different ages were separated into buffer-soluble (S1), sarkosyl- and salt-extractable (S2) and sarkosyl-insoluble pellet (P3) fractions, and analyzed for human tau distribution, phosphorylation and filament formation. S1 and S2 fractions contained 50-60-kDa tau whereas the S2 fraction also had 64-kDa tau. The level of tau in the P3 fraction increased in an age-dependent manner and correlated positively with the soluble tau concentration. The P3 fraction from 2.5-6.5-month-old mice contained 64- and 50-60-kDa tau, whereas that from 8.5-month and older transgenic animals contained mostly 64-kDa and higher molecular weight tau. The S2 and P3 fractions contained comparable amounts of 64-kDa tau. The 64-kDa tau was predominantly human, and phosphorylated at multiple sites: Thr181, Ser202/Thr205, Thr212, Thr231, Ser262, Ser396/Ser404, Ser409 and Ser422. Most of these sites were phosphorylated to a lesser extent in S2 than in P3 fractions. Tau polymers were detected in P3 fractions from 3-month and older female JNPL3 mice, but not in non-transgenic controls. The results suggest that tau in S2 represents an intermediate from which insoluble tau is derived, and that phosphorylation may play a role in filament formation and/or stabilization.
Sahara
Naruhiko
N
Department of Neuroscience, Mayo Clinic, Jacksonville, Florida 32224, USA.
Lewis
Jada
J
DeTure
Michael
M
McGowan
Eileen
E
Dickson
Dennis W
DW
Hutton
Mike
M
Yen
Shu-Hui
SH
D000367:Age Factors; D019943:Amino Acid Substitution; D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000378:metabolism / Q000473:pathology; D001923:Brain Chemistry; D003902:Detergents / Q000737:chemistry; D004195:Disease Models, Animal; D018450:Disease Progression; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006801:Humans; D046911:Macromolecular Substances; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation; D010766:Phosphorylation; D012521:Sarcosine / Q000031:analogs & derivatives* / Q000737:chemistry; D012737:Sex Factors; D012995:Solubility; D024801:Tauopathies / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D016875:tau Proteins / Q000096:biosynthesis* / Q000235:genetics
D003902:Detergents; D046911:Macromolecular Substances; D016875:tau Proteins; C025231:sarkosyl; D012521:Sarcosine