Acetylation mimic of lysine 280 exacerbates human Tau neurotoxicity in vivo

Marianna Karina Gorsky,Jacqueline Dols,Eckhard Mandelkow,Linda Partridge,Sylvie Burnouf

doi:10.1038/srep22685

Abstract

Dysfunction and accumulation of the microtubule-associated human Tau (hTau) protein into intraneuronal aggregates is observed in many neurodegenerative disorders including Alzheimer’s disease (AD). Reversible lysine acetylation has recently emerged as a post-translational modification that may play an important role in the modulation of hTau pathology. Acetylated hTau species have been observed within hTau aggregates in human AD brains and multi-acetylation of hTau in vitro regulates its propensity to aggregate. However, whether lysine acetylation at position 280 (K280) modulates hTau-induced toxicity in vivo is unknown. We generated new Drosophila transgenic models of hTau pathology to evaluate the contribution of K280 acetylation to hTau toxicity, by analysing the respective toxicity of pseudo-acetylated (K280Q) and pseudo-de-acetylated (K280R) mutant forms of hTau. We observed that mis-expression of pseudo-acetylated K280Q-hTau in the adult fly nervous system potently exacerbated fly locomotion defects and photoreceptor neurodegeneration. In addition, modulation of K280 influenced total hTau levels and phosphorylation without changing hTau solubility. Altogether, our results indicate that pseudo-acetylation of the single K280 residue is sufficient to exacerbate hTau neurotoxicity in vivo, suggesting that acetylated K280-hTau species contribute to the pathological events leading to neurodegeneration in AD.

Highlights

Human Tau is a natively unfolded, microtubule-associated protein that regulates the assembly and stabilisation of microtubules in neurons
Post-translationally modified human Tau (hTau) proteins are the main constituents of intraneuronal aggregates observed in Alzheimer’s disease (AD) brains
While hTau hyperphosphorylation has extensively been shown to contribute to hTau toxicity, recent reports implicate acetylated hTau species in the pathological events leading to neurodegeneration in AD2,3,5,7,8

Summary

Introduction

Human Tau (hTau) is a natively unfolded, microtubule-associated protein that regulates the assembly and stabilisation of microtubules in neurons. The generation of a pseudo-acetylated hTau-K280 mutant using a glutamine substitution has revealed that this residue is important for microtubule bundling in cell culture experiments[2]. These experiments suggest a potential role for hTau-K280 in AD pathogenesis. Transgenic fly lines over-expressing the wild-type full length human Tau protein (the 2N4R isoform consisting of 441 amino acids) as well as mutant forms of the latter either mimicking acetylation at lysine 280 with glutamine (K280Q), to model both the charge and chemical structure of acetylated lysine, or abolishing acetylation at this residue while conserving its positive charge, with arginine (K280R)[2,3,15,16,17,18]. We used on one hand a site-directed integration strategy to ensure comparable expression levels among hTau mutants[19] so as to unravel in an unbiased way the effect of the single hTau-K280 mutations in vivo, and on the other hand an inducible driver system to circumvent any developmental effects potentially related to hTau expression

Methods

Results

Conclusion