Acetylation Disfavors Tau Phase Separation.

Josephine Ferreon,Sung Jung,Allan Ferreon,Antrix Jain,Phoebe Tsoi,Kyoung-Jae Choi,Kevin Mackenzie

doi:10.3390/ijms19051360

Josephine Ferreon, Sung Jung + Show 5 more

Open Access

https://doi.org/10.3390/ijms19051360

Copy DOI

Abstract

Neuropathological aggregates of the intrinsically disordered microtubule-associated protein Tau are hallmarks of Alzheimer’s disease, with decades of research devoted to studying the protein’s aggregation properties both in vitro and in vivo. Recent demonstrations that Tau is capable of undergoing liquid-liquid phase separation (LLPS) reveal the possibility that protein-enriched phase separated compartments could serve as initiation sites for Tau aggregation, as shown for other amyloidogenic proteins, such as the Fused in Sarcoma protein (FUS) and TAR DNA-binding protein-43 (TDP-43). Although truncation, mutation, and hyperphosphorylation have been shown to enhance Tau LLPS and aggregation, the effect of hyperacetylation on Tau aggregation remains unclear. Here, we investigate how the acetylation of Tau affects its potential to undergo phase separation and aggregation. Our data show that the hyperacetylation of Tau by p300 histone acetyltransferase (HAT) disfavors LLPS, inhibits heparin-induced aggregation, and impedes access to LLPS-initiated microtubule assembly. We propose that Tau acetylation prevents the toxic effects of LLPS-dependent aggregation but, nevertheless, contributes to Tau loss-of-function pathology by inhibiting Tau LLPS-mediated microtubule assembly.

Highlights

Tau inclusions are key components of neurofibrillary tangles (NFTs) a recurring pathological feature for several neurodegenerative diseases including Alzheimer’s disease (AD) [1,2,3,4]
One is that Tau has intrinsic aggregation motifs that enable fibrillation, leading to gain-in-toxic function(s) [8,9,10,11] exacerbated by the inability of the cellular degradation machinery to remove misfolded or aggregated Tau [12,13]. Another pathological mechanism is that aggregation-promoting Tau accumulation stems from loss-of-normal function(s)
Tau is essential for microtubule dynamics and stability; impairment of this function linked to Tau sequestration into aggregates results in neuronal loss [14]

Summary

Introduction

Tau inclusions are key components of neurofibrillary tangles (NFTs) a recurring pathological feature for several neurodegenerative diseases including Alzheimer’s disease (AD) [1,2,3,4]. One is that Tau has intrinsic aggregation motifs that enable fibrillation, leading to gain-in-toxic function(s) [8,9,10,11] exacerbated by the inability of the cellular degradation machinery to remove misfolded or aggregated Tau [12,13] Another pathological mechanism is that aggregation-promoting Tau accumulation stems from loss-of-normal function(s). Tau is an intrinsically disordered protein (IDP), a class of proteins characterized by a high degree of structural flexibility, conformational heterogeneity and binding promiscuity Often, these properties allow for complex functions involving networks of interactions, and facilitate dysfunctions as a result of misfolding or aggregation [15,16,17]. Since Tau LLPS is expected to be strongly influenced by electrostatics, here, we investigate the role of acetylation in driving LLPS and determine if this role is consistent with the current hypothesis that LLPS can initiate and mediate Tau aggregation

Results and Discussion

In Vitro p300 HAT-Mediated Acetylation Reactions

Western Blot of Acetylated Tau

Mass Spectrometry of Acetylated Tau

Microscopy Imaging

Microtubule Assembly Assay