The RNA helicase DHX36–G4R1 modulates C9orf72 GGGGCC hexanucleotide repeat–associated translation

GGGGCC (G 4 C 2 ) hexanucleotide repeat expansions (HRE) in C9orf72 are the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Repeat-associated non-AUG (RAN) translation of this expansion generates toxic proteins that accumulate in patient brains and contribute to disease pathogenesis. The DEAH-Box Helicase 36 (DHX36/G4R1) plays active roles in RNA and DNA G-quadruplex (G4) resolution in cells. As G 4 C 2 repeats form G4 structures in vitro , we sought to determine the impact of manipulating DHX36 expression on repeat transcription and RAN translation. We found that DHX36 depletion suppresses RAN translation from reporter constructs in a repeat length dependent manner while overexpression of DHX36 enhances RAN translation from G 4 C 2 reporter RNAs. Taken together, these results suggest that DHX36 is active in regulating G 4 C 2 repeat translation, providing potential implications for therapeutic development in nucleotide repeats expansion disorders.