RAN Translation of C9orf72‐Related Dipeptide Repeat Proteins in Zebrafish Recapitulates Hallmarks of Amyotrophic Lateral Sclerosis and Identifies Hypothermia as a Therapeutic Strategy

Abstract

ObjectiveHexanucleotide repeat expansions in the C9orf72 gene are the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). A large body of evidence implicates dipeptide repeats (DPRs) proteins as one of the main drivers of neuronal injury in cell and animal models.MethodsA pure repeat‐associated non‐AUG (RAN) translation zebrafish model of C9orf72‐ALS/FTD was generated. Embryonic and adult transgenic zebrafish lysates were investigated for the presence of RAN‐translated DPR species and adult‐onset motor deficits. Using C9orf72 cell models as well as embryonic C9orf72‐ALS/FTD zebrafish, hypothermic‐therapeutic temperature management (TTM) was explored as a potential therapeutic option for C9orf72‐ALS/FTD.ResultsHere, we describe a pure RAN translation zebrafish model of C9orf72‐ALS/FTD that exhibits significant RAN‐translated DPR pathology and progressive motor decline. We further demonstrate that hypothermic‐TTM results in a profound reduction in DPR species in C9orf72‐ALS/FTD cell models as well as embryonic C9orf72‐ALS/FTD zebrafish.InterpretationThe transgenic model detailed in this paper provides a medium throughput in vivo research tool to further investigate the role of RAN‐translation in C9orf72‐ALS/FTD and further understand the mechanisms that underpin neuroprotective strategies. Hypothermic‐TTM presents a viable therapeutic avenue to explore in the context of C9orf72‐ALS/FTD. ANN NEUROL 2024