%0 Journal Article %J J Alzheimers Dis %D 2016 %T Fibrillar Amyloid-β Accumulation Triggers an Inflammatory Mechanism Leading to Hyperphosphorylation of the Carboxyl-Terminal End of Tau Polypeptide in the Hippocampal Formation of the 3×Tg-AD Transgenic Mouse. %A Ontiveros-Torres, Miguel Ángel %A Labra-Barrios, María Luisa %A Díaz-Cintra, Sofía %A Aguilar-Vázquez, Azucena Ruth %A Moreno-Campuzano, Samadhi %A Flores-Rodríguez, Paola %A Luna-Herrera, Claudia %A Mena, Raúl %A Perry, George %A Florán-Garduño, Benjamín %A Luna-Muñoz, José %A Luna-Arias, Juan Pedro %K Aged %K Aged, 80 and over %K Aging %K Alzheimer Disease %K Amyloid beta-Peptides %K Animals %K Disease Models, Animal %K Female %K Hippocampus %K Humans %K Male %K Mice, Inbred C57BL %K Mice, Transgenic %K Neuroglia %K Phosphorylation %K Plaque, Amyloid %K Presenilin-1 %K Pyramidal Cells %K tau Proteins %X

Alzheimer's disease (AD) is a degenerative and irreversible disorder whose progressiveness is dependent on age. It is histopathologically characterized by the massive accumulation of insoluble forms of tau and amyloid-β (Aβ) asneurofibrillary tangles and neuritic plaques, respectively. Many studies have documented that these two polypeptides suffer several posttranslational modifications employing postmortem tissue sections from brains of patients with AD. In order to elucidate the molecular mechanisms underlying the posttranslational modifications of key players in this disease, including Aβ and tau, several transgenic mouse models have been developed. One of these models is the 3×Tg-AD transgenic mouse, carrying three transgenes encoding APPSWE, S1M146V, and TauP301L proteins. To further characterize this transgenicmouse, we determined the accumulation of fibrillar Aβ as a function of age in relation to the hyperphosphorylation patterns of TauP301L at both its N- and C-terminus in the hippocampal formation by immunofluorescence and confocal microscopy. Moreover, we searched for the expression of activated protein kinases and mediators of inflammation by western blot of wholeprotein extracts from hippocampal tissue sections since 3 to 28 months as well. Our results indicate that the presence of fibrillar Aβ deposits correlates with a significant activation of astrocytes and microglia in subiculum and CA1 regions of hippocampus. Accordingly, we also observed a significant increase in the expression of TNF-α associated to neuritic plaques and glial cells. Importantly, there is an overexpression of the stress activated protein kinases SAPK/JNK and Cdk-5 in pyramidal neurons, which might phosphorylate several residues at the C-terminus of TauP301L. Therefore, the accumulation of Aβ oligomers results in an inflammatory environment that upregulates kinases involved in hyperphosphorylation of TauP301L polypeptide.

%B J Alzheimers Dis %V 52 %P 243-69 %8 2016 03 22 %G eng %N 1 %1 http://www.ncbi.nlm.nih.gov/pubmed/27031470?dopt=Abstract %R 10.3233/JAD-150837 %0 Journal Article %J J Alzheimers Dis %D 2016 %T Spatial Memory Impairment is Associated with Intraneural Amyloid-β Immunoreactivity and Dysfunctional Arc Expression in the Hippocampal-CA3 Region of a Transgenic Mouse Model of Alzheimer's Disease. %A Morin, Jean-Pascal %A Cerón-Solano, Giovanni %A Velázquez-Campos, Giovanna %A Pacheco-López, Gustavo %A Bermúdez-Rattoni, Federico %A Díaz-Cintra, Sofía %K Alzheimer Disease %K Amyloid beta-Peptides %K Amyloid beta-Protein Precursor %K Animals %K Benzeneacetamides %K CA3 Region, Hippocampal %K Cytoskeletal Proteins %K Disease Models, Animal %K Gene Expression Regulation %K Humans %K Maze Learning %K Memory Disorders %K Mice %K Mice, Transgenic %K Mutation %K Nerve Tissue Proteins %K Neurons %K Presenilin-1 %K Pyridines %K tau Proteins %X

Dysfunction of synaptic communication in cortical and hippocampal networks has been suggested as one of the neuropathological hallmarks of the early stages of Alzheimer's disease (AD). Also, several lines of evidence have linked disrupted levels of activity-regulated cytoskeletal associated protein (Arc), an immediate early gene product that plays a central role in synaptic plasticity, with AD "synaptopathy". The mapping of Arc expression patterns in brain networks has been extensively used as a marker of memory-relevant neuronal activity history. Here we evaluated basal and behavior-induced Arc expression in hippocampal networks of the 3xTg-AD mouse model of AD. The basal percentage of Arc-expressing cells in 10-month-old 3xTg-AD mice was higher than wild type in CA3 (4.88% versus 1.77% , respectively) but similar in CA1 (1.75% versus 2.75% ). Noteworthy, this difference was not observed at 3 months of age. Furthermore, although a Morris water maze test probe induced a steep (∼4-fold) increment in the percentage of Arc+ cells in the CA3 region of the 10-month-old wild-type group, no such increment was observed in age-matched 3xTg-AD, whereas the amount of Arc+ cells in CA1 increased in both groups. Further, we detected that CA3 neurons with amyloid-β were much more likely to express Arc protein under basal conditions. We propose that in 3xTg-AD mice, intraneuronal amyloid-β expression in CA3 could increase unspecific neuronal activation and subsequent Arc protein expression, which might impair further memory-stabilizing processes.

%B J Alzheimers Dis %V 51 %P 69-79 %8 2016 %G eng %N 1 %1 http://www.ncbi.nlm.nih.gov/pubmed/26836189?dopt=Abstract %R 10.3233/JAD-150975