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Tau-induced defects in synaptic plasticity, learning, and memory are reversible in transgenic mice after switching off the toxic Tau mutant.

ABSTRACT: This report describes the behavioral and electrophysiological analysis of regulatable transgenic mice expressing mutant repeat domains of human Tau (Tau(RD)). Mice were generated to express Tau(RD) in two forms, differing in their propensity for ?-structure and thus in their tendency for aggregation ("pro-aggregant" or "anti-aggregant") (Mocanu et al., 2008). Only pro-aggregant mice show pronounced changes typical for Tau pathology in Alzheimer's disease (aggregation, missorting, hyperphosphorylation, synaptic and neuronal loss), indicating that the ?-propensity and hence the ability to aggregate is a key factor in the disease. We now tested the mice with regard to neuromotor parameters, behavior, learning and memory, and synaptic plasticity and correlated this with histological and biochemical parameters in different stages of switching Tau(RD) on or off. The mice are normal in neuromotor tests. However, pro-aggregant Tau(RD) mice are strongly impaired in memory and show pronounced loss of long-term potentiation (LTP), suggesting that Tau aggregation specifically perturbs these brain functions. Remarkably, when the expression of human pro-aggregant Tau(RD) is switched on for ? 10 months and off for ? 4 months, memory and LTP recover, whereas aggregates decrease moderately and change their composition from mixed human plus mouse Tau to mouse Tau only. Neuronal loss persists, but synapses are partially rescued. This argues that continuous presence of amyloidogenic pro-aggregant Tau(RD) constitutes the main toxic insult for memory and LTP, rather than the aggregates as such.

SUBMITTER: Sydow A

PROVIDER: S-EPMC6623704 | biostudies-literature | 2011 Feb

REPOSITORIES: biostudies-literature

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Tau-induced defects in synaptic plasticity, learning, and memory are reversible in transgenic mice after switching off the toxic Tau mutant.

Sydow Astrid A Van der Jeugd Ann A Zheng Fang F Ahmed Tariq T Balschun Detlef D Petrova Olga O Drexler Dagmar D Zhou Lepu L Rune Gabriele G Mandelkow Eckhard E D'Hooge Rudi R Alzheimer Christian C Mandelkow Eva-Maria EM

The Journal of neuroscience : the official journal of the Society for Neuroscience 20110201 7

This report describes the behavioral and electrophysiological analysis of regulatable transgenic mice expressing mutant repeat domains of human Tau (Tau(RD)). Mice were generated to express Tau(RD) in two forms, differing in their propensity for β-structure and thus in their tendency for aggregation ("pro-aggregant" or "anti-aggregant") (Mocanu et al., 2008). Only pro-aggregant mice show pronounced changes typical for Tau pathology in Alzheimer's disease (aggregation, missorting, hyperphosphoryl ...[more]

PMID: 21325519

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Project description:Parkinson's disease dementia (PDD) and dementia with Lewy bodies (DLB) are clinically and neuropathologically highly related α-synucleinopathies that collectively constitute the second leading cause of neurodegenerative dementias. Genetic and neuropathological studies directly implicate α-synuclein (αS) abnormalities in PDD and DLB pathogenesis. However, it is currently unknown how αS abnormalities contribute to memory loss, particularly since forebrain neuronal loss in PDD and DLB is less severe than in Alzheimer's disease. Previously, we found that familial Parkinson's disease-linked human mutant A53T αS causes aberrant localization of the microtubule-associated protein tau to postsynaptic spines in neurons, leading to postsynaptic deficits. Thus, we directly tested if the synaptic and memory deficits in a mouse model of α-synucleinopathy (TgA53T) are mediated by tau. TgA53T mice exhibit progressive memory deficits associated with postsynaptic deficits in the absence of obvious neuropathological and neurodegenerative changes in the hippocampus. Significantly, removal of endogenous mouse tau expression in TgA53T mice (TgA53T/mTau-/-), achieved by mating TgA53T mice to mouse tau-knockout mice, completely ameliorates cognitive dysfunction and concurrent synaptic deficits without affecting αS expression or accumulation of selected toxic αS oligomers. Among the known tau-dependent effects, memory deficits in TgA53T mice were associated with hippocampal circuit remodeling linked to chronic network hyperexcitability. This remodeling was absent in TgA53T/mTau-/- mice, indicating that postsynaptic deficits, aberrant network hyperactivity, and memory deficits are mechanistically linked. Our results directly implicate tau as a mediator of specific human mutant A53T αS-mediated abnormalities related to deficits in hippocampal neurotransmission and suggest a mechanism for memory impairment that occurs as a consequence of synaptic dysfunction rather than synaptic or neuronal loss. We hypothesize that these initial synaptic deficits contribute to network hyperexcitability which, in turn, exacerbate cognitive dysfunction. Our results indicate that these synaptic changes present potential therapeutic targets for amelioration of memory deficits in α-synucleinopathies.

Dataset Information

Tau-induced defects in synaptic plasticity, learning, and memory are reversible in transgenic mice after switching off the toxic Tau mutant.

Publications

Tau-induced defects in synaptic plasticity, learning, and memory are reversible in transgenic mice after switching off the toxic Tau mutant.

Similar Datasets

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