title: Tau oligomers impair memory and induce synaptic and mitochondrial dysfunction in wild-type mice.
abstract: BACKGROUND
  The correlation between neurofibrillary tangles of tau and disease progression in the brains of Alzheimer's disease (AD) patients remains an area of contention. Innovative data are emerging from biochemical, cell-based and transgenic mouse studies that suggest that tau oligomers, a pre-filament form of tau, may be the most toxic and pathologically significant tau aggregate.
  
  
  RESULTS
  Here we report that oligomers of recombinant full-length human tau protein are neurotoxic in vivo after subcortical stereotaxic injection into mice. Tau oligomers impaired memory consolidation, whereas tau fibrils and monomers did not. Additionally, tau oligomers induced synaptic dysfunction by reducing the levels of synaptic vesicle-associated proteins synaptophysin and septin-11. Tau oligomers produced mitochondrial dysfunction by decreasing the levels of NADH-ubiquinone oxidoreductase (electron transport chain complex I), and activated caspase-9, which is related to the apoptotic mitochondrial pathway.
  
  
  CONCLUSIONS
  This study identifies tau oligomers as an acutely toxic tau species in vivo, and suggests that tau oligomers induce neurodegeneration by affecting mitochondrial and synaptic function, both of which are early hallmarks in AD and other tauopathies. These results open new avenues for neuroprotective intervention strategies of tauopathies by targeting tau oligomers.
authors.affiliation: George P, and Cynthia Woods Mitchell Center for Neurodegenerative Diseases, Departments of Neurology, and Neuroscience and Cell Biology, The University of Texas Medical Branch, Galveston, TX 77555-1045, USA. rakayed@utmb.edu.
authors.forename: Cristian A
authors.initials: CA
authors.lastname: Lasagna-Reeves
authors.forename: Diana L
authors.initials: DL
authors.lastname: Castillo-Carranza
authors.forename: Urmi
authors.initials: U
authors.lastname: Sengupta
authors.forename: Audra L
authors.initials: AL
authors.lastname: Clos
authors.forename: George R
authors.initials: GR
authors.lastname: Jackson
authors.forename: Rakez
authors.initials: R
authors.lastname: Kayed