Poster Presentation The 45th Lorne Conference on Protein Structure and Function 2020

Developing novel frontotemporal dementia therapeutics to rescue TDP-43 mistranslocation and facilitate clearance (#305)

Hei Wun Alison Cheng 1 , Timothy Callis 2 , Andrew P Montgomery 2 , William Jorgensen 2 , Jonathan J Danon 2 , Lars M Ittner 3 , Eryn L Werry 2 , Michael Kassiou 2
  1. Department of Pharmacology, University of Sydney, Camperdown, NSW, Australia
  2. School of Chemistry, University of Sydney, Camperdown, NSW, Australia
  3. Department of Biomedical Sciences, Macquarie University, Macquarie Park, NSW, Australai

Introduction:

The trans-activation response DNA-binding protein (TDP-43) is a DNA/RNA-binding protein located in the nucleus. It is involved in regulating alternative splicing processes and transcriptional activities of RNA.1 A common key pathological hallmark in amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) is the abnormal aggregation and mislocalization of TDP-43 from the nucleus to the cytoplasm.2In vivo studies have shown that the selective reduction of mislocalized TDP-43 from the cytoplasm is linked to reduced toxicity.3 Since there are currently no treatments which reverse ALS and FTD, TDP-43 represents a promising target to develop novel therapeutic options.

 

Aim:

To identify novel compounds that can aid in the clearance of cytoplasmic TDP-43 and/or translocate TDP-43 from the cytoplasm back into the nucleus.

 

Methods:

Human neuroblastoma SH-SY5Y cells stably transfected with disease-relevant TDP-43 M337V mutants were treated with 12 compounds (300 nM) for 4 hours. Cells were fractionated into their cytoplasmic and nuclear fractions. Western blots were performed to determine the effect of compounds on TDP-43 translocation and cytoplasmic clearance.

 

Results and Discussion:

Compounds JD2-180, TC_ELN197 and TC_ELN215 significantly decreased TDP-43 in the cytoplasm as compared to control (p<0.05).  TC_ELN215 was the most effective at decreasing cytoplasmic M337V TDP-43 (no treatment vs TC_ELN215= 0.569 ± 0.008 vs 0.393 ± 0.080, n=3, mean ± SD). These three compounds had no effect on nuclear TDP-43 levels. This suggests that these compounds are able to aid in the clearance of toxic cytoplasmic TDP-43, but are unable to translocate cytoplasmic TDP-43 back into the nucleus.

 

Conclusion: 

We have successfully identified three novel compounds that can selectively decrease mislocated cytoplasmic TDP-43 with no effect on TDP-43 in the nucleus. This provides a scaffold for rational design of more efficacious compounds. Further research will investigate other functional activities such as effects on TDP-43 phosphorylation and other disease-related post-translational modifications.

 

 

 

  1. Lagier-Tourenne C, Polymenidou M, & Cleveland DW (2010). TDP-43 and FUS/TLS: emerging roles in RNA processing and neurodegeneration. Human molecular genetics 19: R46-R64.
  2. Neumann M, Sampathu DM, Kwong LK, et al. (2006). Ubiquitinated TDP-43 in frontotemporal lobar degeneration and amyotrophic lateral sclerosis. Science 314: 130-133.
  3. Kabashi E, Lin L, Tradewell ML, Dion PA, et al. (2009). Gain and loss of function of ALS-related mutations of TARDBP (TDP-43) cause motor deficits in vivo. Human Molecular Genetics 19: 671-683.