Viral-based Therapeutic Approaches for Reversal of ALS Pathology

PROJECT SUMMARY/ABSTRACT
Amyotrophic lateral sclerosis (ALS) is a fatal disease characterized by death of motor neurons. A key pathologic
feature is the cytoplasmic mislocalization of a nuclear transcription and splice regulator, Tar-DNA binding protein
of 43kDa (TDP-43). TDP-43 is aggregated in cytoplasmic stress granules (SGs) along with nuclear import/export
factors, and its toxicity is thought to be due to both cytoplasmic gain- and nuclear loss-of-function mechanisms.
Relocating it to the nucleus has the potential to address both forms of toxicity. Inhibiting formation of SGs is one
promising strategy, and downregulating the SG-associated protein Ataxin-2 (Atxn2) using antisense
oligonucleotides (ASOs) prolongs strength and survival in a mouse model of ALS. However, ASOs require
frequent CNS readministration, and a preferable approach would be to achieve knockdown after one treatment.
A second approach is enhancing nuclear import, a strategy with success in dipeptide repeat (DPR) toxicity
models of ALS in vitro. Extending this strategy to non-DPR forms of ALS has the potential to make a broad
impact on the disease. In addition, potential synergy between the two approaches has great therapeutic potential.
If successful, these strategies could be used to treat the vast majority of ALS.
In preliminary work, RNAi delivered using a novel viral vector achieves robust knockdown of Atxn2 in the key
areas of the nervous system affected in ALS. Aim 1 of this proposal is to determine if sustained Atxn2 knockdown
in these regions reverses TDP-43 mislocalization and improves neuron survival in two distinct mouse models of
ALS. In other preliminary work, cell lines overexpressing a nuclear import factor show reductions in TDP-43. Aim
2 is to test if augmenting nuclear import corrects TDP-43 localization and improves cell survival under conditions
of stress. My central hypothesis is that targeting both cytoplasmic aggregation and nuclear loss of TDP-43 using
viral-mediated approaches will result in sustained neuroprotection. This work fits squarely in NINDS’ mission to
further our knowledge about the brain and nervous system and to use this knowledge to reduce the burden of
disease, specifically targeting one of neurology’s most devastating afflictions.
Dr. Amado is a passionate, highly-trained clinician-scientist uniquely poised to make a fundamental impact
on ALS. Her mentor Dr. Beverly Davidson, a renowned neurodegenerative disease expert continually pushing
the boundaries of vector-based therapeutics, and her advisory committee of deeply experienced and dedicated
neurologists and neuroscientists, will provide the guidance and mentorship to ensure her success, backed by
enthusiastic institutional support. The University of Pennsylvania, with its innumerable resources and facilities,
is an outstanding place to launch a neuroscience career. Dr. Amado will use this 5-year mentored opportunity to
build on her gene therapy training and merge it with her clinical expertise to become an independent, R01-funded
physician-scientist developing novel therapies for patients with ALS.

Grant Number: 5K08NS114106-05
NIH Institute/Center: NIH
Principal Investigator: Defne Amado