Authors
You Wu, Li Li, Jing Tian, Leilei Liu, Kunzhao Du, Zhicheng Shao, Tianlin Cheng, Xin Cao, Tao Wang
Published in
International journal of molecular sciences. Volume 27. Issue 15. Aug 04, 2026. Epub Aug 04, 2026.
Abstract
The RNA exosome plays a critical role in surveilling nuclear mRNA biogenesis and regulating co-translational mRNA decay in the cytoplasm. Unlike canonical translation, repeat-associated non-AUG (RAN) translation of a GGGGCC hexanucleotide repeat expansion (HRE) within an intron of the C9orf72 locus leads to the synthesis of neurotoxic dipeptide-repeat (DPR) proteins, contributing to the pathogenesis of frontotemporal dementia and amyotrophic lateral sclerosis (C9-ALS/FTD). However, it remains unclear whether aberrant RAN translation is monitored and regulated co-translationally or how C9orf72 HRE (C9-HRE) mRNA is degraded during this process. Here, we demonstrate that RAN translation triggers the rapid decay of C9-HRE mRNA. During this process, the RNA exosome engages the translating ribosome-C9-HRE mRNA complex to mediate RAN translation-coupled mRNA decay. Moreover, overexpression of EXOSC3, a key subunit of the RNA exosome cap, promotes RAN translation-coupled decay of C9-HRE mRNA and suppresses DPR production. In iPSC-derived neurons, a reduction in EXOSC3 levels blocks C9-HRE mRNA decay in a translation-dependent manner, further confirming its role in RAN translation surveillance. These findings highlight the essential function of the RNA exosome, particularly EXOSC3, in mitigating RAN translation-associated toxicity and preventing pathological DPR production. This work provides insights into potential therapeutic strategies for C9-ALS/FTD and may have broader implications for other disorders involving RAN translation.
PMID:
42589639
Bibliographic data and abstract were imported from PubMed on 13 Oct 2026.
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