Investigation of role of TDP-43 aggregation on heterologous aggregating proteins and modulation of TDP-43 aggregation by small molecules

Girdhar, Amandeep and Patel, Basant Kumar (2020) Investigation of role of TDP-43 aggregation on heterologous aggregating proteins and modulation of TDP-43 aggregation by small molecules. PhD thesis, Indian Institute of Technology Hyderabad.

Full text not available from this repository. (Request a copy)

Abstract

Misfolded and aggregated TAR DNA binding protein-43 (TDP-43), with either wild-type or mutant protein sequence, is found in most cases of amyotrophic lateral sclerosis (ALS) disorder which manifests as progressive degeneration of motor neurons and muscles leading to death. TDP-43 inclusions are also hallmark of frontotemporal lobar degeneration-TDP disorder, but its co-aggregation in numerous other neurodegenerative diseases such as Alzheimer‟s (AD), Huntington‟s (HD) and Parkinson‟s (PD) diseases remain ambiguous. As TDP-43 is a highly aggregationprone protein, we examined the potential of TDP-43-DsRed as an amyloidenhancing factor to promote the aggregation of Poly-Q103-GFP, Aβ42-EGFP and Transthyretin proteins, respectively, relevant to the pathologies of HD, AD and Transthyretin amyloidosis diseases. Using yeast cellular model, we show that coexpression and aggregation of TDP-43-DsRed accelerates the aggregation of PolyQ103-GFP and Aβ42-EGFP in [pin- ] yeast cells, whereas Poly-Q103-GFP aggregates in [PIN+ ] as well and the early aggregates of both proteins were found to be colocalized with TDP-43-DsRed aggregates. On the contrary, aggregation of TDP-43- DsRed restricted M-TTR-GFP aggregation in [pin- ] yeast. Further, the impact of Hsp40 chaperone Sis1 on Poly-Q103-GFP aggregation altered differently due to presence of TDP-43 aggregation in [PIN+ ] and [pin- ] yeast. In case of Aβ-42-EGFP aggregation, overexpression of chaperone Sis1 mitigated the TDP-43-mediated enhancement of aggregation in yeast. Later, sodium azide-induced cellular stress, which is known to enhance TDP-43-DsRed aggregation, was implicated that enhanced the ability of TDP-43-DsRed to promote Poly-Q103-GFP and Aβ-42-EGFP aggregation in the [pin- ] yeast. The stimulated aggregation of Poly-Q103-GFP and Aβ-42-EGFP in yeast by TDP-43-DsRed aggregates, may prime the understanding of TDP-43‟s occurrence in the inclusions of HD and AD. TDP-43‟s cytoplasmic mis-localization, liquid-liquid phase separation (LLPS) and aggregation are proposedly important for TDP-43-toxicity in ALS. So far, therapeutic options for ALS are minimal and ineffective therefore, multi-faceted approaches like targeting oxidative stress and inhibiting TDP-43 aggregation are being pursued. Recently, an acridine-imidazolium derivative, AIM4, with anti-TDP-43 aggregation propensity has been identified. The study focuses to estimate the unknown mechanism of inhibition, where, potential binding site for AIM4 in the TDP-43 structure have been examined by computational methods. AIM4 could also inhibit the in vitro amyloidlike aggregation and LLPS of a familial ALS A315T mutant of TDP-432C . The antagonistic effects of AIM4 on LLPS need further investigations towards ALS therapeutic research.

[error in script]

IITH Creators: