Dataset Information

Comparison of N-Acetyl-Glucosamine to Other Monosaccharides Reveals Structural Differences for the Inhibition of α-Synuclein Aggregation.

ABSTRACT: O-GlcNAc modification of the microtubule associated protein tau and α-synuclein can directly inhibit the formation of the associated amyloid fibers associated with major classes of neurodegenerative diseases. However, the mechanism(s) by which this posttranslational modification (PTM) inhibit amyloid aggregation are still murky. One hypothesis is that O-GlcNAc simply acts as a polyhydroxylated steric impediment to the formation of amyloid oligomers and fibers. Here, we begin to test this hypothesis by comparing the effects of O-GlcNAc to other similar monosaccharides-glucose, N-acetyl-galactosamine (GalNAc), or mannose-on α-synuclein amyloid formation. Interestingly, we find that this quite reasonable hypothesis is not entirely correct. More specifically, we used four types of biochemical and biophysical assays to discover that the different sugars display different effects on the inhibition of amyloid formation, despite only small differences between the structures of the monosaccharides. These results further support a more detailed investigation into the mechanism of amyloid inhibition by O-GlcNAc and has potential implications for the evolution of N-acetyl-glucosamine as the monosaccharide of choice for widespread intracellular glycosylation.

SUBMITTER: Galesic A

PROVIDER: S-EPMC8142260 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Comparison of N-Acetyl-Glucosamine to Other Monosaccharides Reveals Structural Differences for the Inhibition of α-Synuclein Aggregation.

Galesic Ana A Rakshit Ananya A Cutolo Giuliano G Pacheco Ricardo Palos RP Balana Aaron T AT Moon Stuart P SP Pratt Matthew R MR

ACS chemical biology 20210105 1

O-GlcNAc modification of the microtubule associated protein tau and α-synuclein can directly inhibit the formation of the associated amyloid fibers associated with major classes of neurodegenerative diseases. However, the mechanism(s) by which this posttranslational modification (PTM) inhibit amyloid aggregation are still murky. One hypothesis is that O-GlcNAc simply acts as a polyhydroxylated steric impediment to the formation of amyloid oligomers and fibers. Here, we begin to tes ...[more]

PMID: 33399442

Similar Datasets

Project description:While several polyphenols were found to either inhibit or modulate the aggregation of proteins implicated in neurodegenerative diseases, such as Parkinson's disease (PD), discrepant action mechanisms have been reported. This, in addition to some polyphenols' pan-assay interference compounds' reputation, casts some doubts concerning their therapeutic relevance. Here, we studied, through molecular dynamics and enhanced sampling methods, the aggregation of 11-mer peptides from the non-amyloid-β component, an aggregation-prone domain of α-synuclein (α-syn) implicated in PD and other synucleinopathies, in neat water and aqueous solutions of resveratrol (RSV) and gallic acid (GA). Further, simulations of the complete protein were carried out in aqueous urea, RSV, and GA solutions. Our results show that peptide aggregation is not disrupted by either phenolic compound. Thus, instead, intrusion of RSV and GA in the inter-peptide region induces a peptide-peptide re-orientation, favoring terminal interactions that manifest in the formation of barrierless solvent-separated configurations. Moreover, although the (poly)phenols induce a pronounced peptide dewetting at high concentrations, β-sheet-rich regions, a hallmark of α-syn aggregation, are not disrupted. Thus, our results indicate that, if anything, RSV and GA delay or modulate peptide aggregation at high concentrations via the stabilization of solvent-separated conformations as opposed to aggregation inhibition. Structural analysis of the full protein, however, shows that the (poly)phenols induce more extended conformations of α-syn, similar to urea, possibly also influencing its aggregation propensity. However, opposite to urea, the (poly)phenols reduce α-syn's conformational space, likely due to steric effects and a slowdown of the solvent dynamics. These effects are concentration-dependent and possibly unattainable at therapeutic-relevant concentrations. These results suggest that the aggregation inhibition activity of RSV and GA in vitro should involve, instead, either the non-covalent binding to oligomeric intermediates or the stabilization of the monomer and/or oligomers through the formation of covalent bonds of the respective quinones with α-syn. In addition, the enhanced aggregation tendency of the peptides observed here could be associated with the formation of non-toxic oligomers, reported for some polyphenols.

Project description:Methamphetamine (METH) is an illegal and widely abused psychoactive stimulant. METH abusers are at high risk of neurodegenerative disorders, including Parkinson's disease (PD). Previous studies have demonstrated that METH causes alpha-synuclein (α-syn) aggregation in the both laboratory animal and human. In this study, exposure to high METH doses increased the expression of α-syn and the small ubiquitin-related modifier 1 (SUMO-1). Therefore, we hypothesized that SUMOylation of α-syn is involved in high-dose METH-induced α-syn aggregation. We measured the levels of α-syn SUMOylation and these enzymes involved in the SUMOylation cycle in SH-SY5Y human neuroblastoma cells (SH-SY5Y cells), in cultures of C57 BL/6 primary mouse neurons and in brain tissues of mice exposure to METH. We also demonstrated the effect of α-syn SUMOylation on α-syn aggregation after METH exposure by overexpressing the key enzyme of the SUMOylation cycle or silencing SUMO-1 expression in vitro. Then, we make introduced mutations in the major SUMOylation acceptor sites of α-syn by transfecting a lentivirus containing the sequence of WT α-syn or K96/102R α-syn into SH-SY5Y cells and injecting an adenovirus containing the sequence of WT α-syn or K96/102R α-syn into the mouse striatum. Levels of the ubiquitin-proteasome system (UPS)-related makers ubiquitin (Ub) and UbE1, as well as the autophagy-lysosome pathway (ALP)-related markers LC3, P62 and lysosomal associated membrane protein 2A (LAMP2A), were also measured in SH-SY5Y cells transfected with lentivirus and mice injected with adenovirus. The results showed that METH exposure decreases the SUMOylation level of α-syn, although the expression of α-syn and SUMO-1 are increased. One possible cause is the reduction of UBC9 level. The increase in α-syn SUMOylation by UBC9 overexpression relieves METH-induced α-syn overexpression and aggregation, whereas the decrease in α-syn SUMOylation by SUMO-1 silencing exacerbates the same pathology. Furthermore, mutations in the major SUMOylation acceptor sites of α-syn also aggravate α-syn overexpression and aggregation by impairing degradation through the UPS and the ALP in vitro and in vivo. These results suggest that SUMOylation of α-syn plays a fundamental part in α-syn overexpression and aggregation induced by METH and could be a suitable target for the treatment of neurodegenerative diseases.

Dataset Information

Comparison of N-Acetyl-Glucosamine to Other Monosaccharides Reveals Structural Differences for the Inhibition of α-Synuclein Aggregation.

Publications

Comparison of <i>N</i>-Acetyl-Glucosamine to Other Monosaccharides Reveals Structural Differences for the Inhibition of α-Synuclein Aggregation.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets