Prion-like C-terminal domain of TDP-43 and α-Synuclein interact synergistically to generate neurotoxic hybrid fibrils

Abstract

Aberrant aggregation and amyloid formation of tar DNA binding protein (TDP-43) and α-synuclein (αS) underlie frontotemporal dementia (FTD) and Parkinson’s disease (PD), respectively. Amyloid inclusions of TDP-43 and αS are also commonly co-observed in amyotrophic lateral sclerosis (ALS), dementia with Lewy bodies (DLB) and Alzheimer disease (AD). Emerging evidence from cellular and animal models show colocalization of the TDP-43 and αS aggregates, raising the possibility of direct interactions and co-aggregation between the two proteins. In this report, we set out to answer this question by investigating the interactions between αS and prion-like pathogenic C-terminal domain of TDP-43 (TDP-43 PrLD). PrLD is an aggregation-prone fragment generated both by alternative splicing as well as aberrant proteolytic cleavage of full length TDP-43. Our results indicate that two proteins interact in a synergistic manner to augment each others aggregation towards hybrid fibrils. While monomers, oligomers and sonicated fibrils of αS seed TDP-43 PrLD monomer aggregation, TDP-43 PrLD fibrils failed to seed αS monomers indicating selective interactions. Furthermore, αS modulates liquid droplets formed by TDP-43 PrLD and RNA to promote insoluble amyloid aggregates. Importantly, the cross-seeded hybrid aggregates show greater cytotoxicity as compared to the individual homotypic aggregates suggesting that the interactions between the two proteins have a discernable impact on cellular functions. Together, these results bring forth insights into TDP-43 PrLD – αS interactions that could help explain clinical and pathological presentations in patients with co-morbidities involving the two proteins.

Liquid-liquid phase separation regulates alpha-synuclein aggregate and mitophagy in Parkinson’s disease

“…e.g., the proline-rich P2 region of tau protein interacts with the α-syn C-terminus to recruit α-syn into tau condensates (Siegert et al, 2021). TDP-43 prion-like structural domain monomers promote fibril formation and exhibit enhanced cytotoxicity when co-incubated with α-syn (Dhakal et al, 2021;Agarwal et al, 2022). The interaction of the positively charged N-terminal of Prion protein with the negatively charged C-terminal of α-syn synergistically promotes LLPS condensate formation and liquid-to-solid transition (Agarwal et al, 2022).…”

Targeting stress granules in neurodegenerative diseases: A focus on biological function and dynamics disorders

“…Meanwhile, the synergistic effect of tau and α‐synuclein worsens PD dementia, which may be mediated by LLPS 95,96 . Moreover, α‐synuclein is colocalized with TDP‐43 in stressed cells and promotes phase‐separated TDP‐43 droplets 97 . On the other hand, it has been discovered that G3BP1 is deficient in the brains of PD patients, and G3BP1 depletion promotes α‐synuclein aggregation, which may be mediated by interaction among G3BP1 with p62 and USP10.…”

αS oligomers generated from polyunsaturated fatty acid and dopamine metabolite differentially interact with Aβ to enhance neurotoxicity

“…Recombinant expression and purification of αS and Aβ were carried out following previously established protocol [40,41]. Briefly, αS and Aβ42 plasmid were transformed and grown in E.…”

“…Cell viability assay was carried out using 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium hydroxide (XTT) in SH-SY5Y cells as described in our previously established protocols [40,43]. Briefly, human neuroblastoma SH-SY5Y were maintained at 37 °C with 5.5 % CO2 in DMEM: F12 (1:1) media containing 10% FBS and 1% penicillin/streptomycin.…”