Tau K321/K353 pseudoacetylation within KXGS motifs regulates tau–microtubule interactions and inhibits aggregation

Abstract

Alzheimer’s disease is the leading cause of dementia and a defining hallmark is the progressive brain deposition of tau aggregates. The insidious accumulation of brain tau inclusions is also involved in a group of neurodegenerative diseases termed frontotemporal dementias. In all of these disorders, tau aggregates are enriched in post-translational modifications including acetylation, which has recently been identified at multiple sites. While most evidence suggest that tau acetylation is detrimental and promotes tau aggregation, a few studies support that tau acetylation within the KXGS motif can be protective and inhibit tau aggregation. To model site-specific acetylation at K259, K290, K321, and K353, acetylmimetics were created by mutating lysine to glutamine residues, which approximates size and charge of acetylation. HEK293T cells were transfected to express wild type tau, tau pathogenic mutations (P301L and P301L/S320F) or tau acetylmimetics and assessed by cell-based assays for microtubule binding and tau aggregation. Acetylmimetics within the KXGS motif (K259Q, K290Q, K321Q, K353Q) leads to significant decreased tau–microtubule interactions. Acetylmimetics K321Q and K353Q within the context of the pathogenic P301L tau mutation strongly inhibited prion-like seeded aggregation. This protective effect was confirmed to decrease intrinsic aggregation of P301L/S320F tau double mutation. Surprisingly, K321Q and K353Q acetylmimetics altered the conformational structure of P301L/S320F tau to extensively impair Thioflavin S binding. Site-specific acetylation of tau at K321 and K353 could represent a natural protective mechanism against tau aggregation and could be a potential therapeutic target.

Reassessment of Neuronal Tau Distribution in Adult Human Brain and Implications for Tau Pathobiology

“…Mouse monoclonal antibodies, CP27 and PHF-1 were generous gifts from the late Dr. Peter Davies [ 26 , 60 ]. Total Tau 3026 rabbit polyclonal antibody was previously described [ 68 , 81 ]. Mouse monoclonal antibody Tau-5 was purchased from Invitrogen (Waltham, MA).…”

Molecular Insights into the Differential Effects of Acetylation on the Aggregation of Tau Microtubule-Binding Repeats

“…Acetylation of K280 and K321 may exhibit a distinct effect on the aggregation of tau. Previous studies have reported that K280 acetylation increases the aggregation of tau, , while some experimental works demonstrated the protective effects against tau aggregation by K321 acetylation. , To elucidate the underlying mechanisms by which acetylation affects tau aggregation at the atomic level, we performed 500 ns REMD simulations on the R2 dimer with acetylated K280 and the R3 dimer with acetylated K321. We first explored the influence of K280 acetylation on the conformational ensembles of the R2 dimer by calculating the average probability of each type of secondary structure and residue-based β-sheet probability in the R2 and R2-K280 systems.…”

“…Although most evidence suggests that tau acetylation contributes to disease, several studies have reported that specific acetylation sites, e.g., lysine 321 (K321), could be protective in tau aggregation. , Previous in vitro experiments revealed that tau acetylation on K321 could significantly impede tau filament assembly and inhibit phosphorylation on serine 324 . Xia et al pointed out that single acetylation site at either K321 or K353 could be sufficient to prevent or slow the formation of tau filaments, which may represent a natural protective mechanism against tau aggregation . Despite these studies, the underlying molecular mechanisms by which acetylation of tau protein at the K280 or K321 site affects tau aggregation are still not fully understood.…”

A hybrid approach unveils drug repurposing candidates targeting an Alzheimer pathophysiology mechanism

“… 49 While some groups report a protective effect of HDAC6, 50 others suggest that inhibiting this protein can lead to improvement. 51 , 52 Some of these effects might be cell line specific or more relevant for certain tau isoforms, which adds another layer of complexity. The N2a cells used in this study represent a simple and robust model, which expresses many different tau isoforms.…”