September 29, 2021

Developing and testing an ASO therapy in cellular and iPSC-patient models of dentatorubral-pallidoluysian atrophy (DRPLA)

Joanna Korecka, PhD

Additional Authors: Tojo Nakayama, Boxun Zhao, Renata DiDonato, Charlotte Oettgen, Victoria Suslovitch, Aazam Vahdatshoar, Sophie Stroeks, Diana Chin, Aubrie Soucy, Timothy W. Yu and Vikram Khurana

Background: Dentatorubral-pallidoluysian atrophy (DRPLA) is a rare, progressive brain disorder caused by a CAG trinucleotide expansion within the atrophin-1 gene, ATN1. There is currently no treatment for DRPLA and little is known about the consequence of ATN1 polyQ expansion on neuronal function. Antisense oligonucleotide (ASO)-based therapy is a promising strategy for this disorder.

Methods: A high throughput ASO screen was designed in BE(2)M-17 neuroblastoma cell line and DRPLA patient induced pluripotent stem cells (iPSC)-derived neurons to reduce ATN1 levels through RNAse H-mediated mRNA knockdown. CRISPR/Cas9 ATN1 knockout (KO) in iPSCs, neuronal precursor cells and iPSC-derived neurons is underway to compare the effect of ATN1 KO on cell survival, proliferation, differentiation, and neuronal function to 1. improve our understanding of ATN1 function, and 2. infer the safety of ATN1 knockdown in the adult CNS as a clinical strategy.

Results & Conclusions: We identified a number of 2’MOE RNAse H gapmer ASOs targeting ATN1 exonic sequences that demonstrate efficient mRNA knockdown. Preliminary data shows that the increased polyQ expansion in DRPLA patient-derived iPSCs results in accumulation of intracellular p62 aggregates. Future studies will test for rescue of the observed phenotypes with either ASO-mediated ATN1 mRNA knockdown and/or CRISPR-mediated CAG copy number reduction.

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