Multi-level repression ensures tight translation control of C9ORF72
Abstract
C9ORF72 is involved in multiple neuronal functions and a major factor in Amyotrophic Lateral Sclerosis, a fatal neurodegenerative disease. Pathogenicity is implemented through an intronic repeat expansion in the gene’s mRNA leader that produces long, repetitive RNA and dipeptides when translated through repeat associated non-canonical translation. The expanded repeat also suppresses transcription of the major transcript variant (Variant 2) which comprises 90% of the C9ORF72 levels in healthy cells, leading to an additional loss-of-function effect. Examining the sequence, structure, and ribosome occupancy of Variant 2’s mRNA leader in detail, we found that translation of C9ORF72 is tightly regulated through a multi-layered system. To deconvolute this system, we conducted a mutant screen and developed a method to evaluate the results quantitatively. We found that near-cognate start codons in all three frames, a start-stop element in frame 2, a uTranslon in frame 1, and secondary structures cooperate to keep baseline C9ORF72 translation low. Further, initiation at upstream near-cognate start codons reduces the impact of both the start-stop and the uTranslon, effectively buffering their repressive function and creating a feedforward loop. A strong secondary structure in the Variant 2-specific sequence further modulates initiation at all the elements. We hypothesize that this buffered repressor system has evolved to ensure reliable, noise-insensitive expression of this critical regulator of neuronal function. Finally, we used ADAR-based RNA editing of specific sites in Variant 2’s mRNA leader, increasing translation of the gene and providing a novel avenue to rescue the loss-of-function phenotype in disease.
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BibTeX
@misc{haizel2026multilevel,
title = {{Multi-level repression ensures tight translation control of C9ORF72}},
author = {Solomon A. Haizel and Alfredo Vidal Ceballos and Alice Nayoung Ko and Lucas Lyu and Lauren Manning and Xinyi Ge and Violet Park and Huijing Zou and Churong Cheng and Richmond Afful and Serena Kher and Anthony Widjaja and Joanetta Jean-Baptiste and Sasha Khazhinsky and Pieter Spealman and Alisha N. Jones and Leos Shivaya Valasek and Christine Vogel},
howpublished = {bioRxiv},
year = {2026},
month = oct,
doi = {10.1101/2025.08.09.669471},
url = {https://doi.org/10.1101/2025.08.09.669471},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Multi-level repression ensures tight translation control of C9ORF72
AU - Solomon A. Haizel
AU - Alfredo Vidal Ceballos
AU - Alice Nayoung Ko
AU - Lucas Lyu
AU - Lauren Manning
AU - Xinyi Ge
AU - Violet Park
AU - Huijing Zou
AU - Churong Cheng
AU - Richmond Afful
AU - Serena Kher
AU - Anthony Widjaja
AU - Joanetta Jean-Baptiste
AU - Sasha Khazhinsky
AU - Pieter Spealman
AU - Alisha N. Jones
AU - Leos Shivaya Valasek
AU - Christine Vogel
PY - 2026
DA - 2026/10/22
PB - bioRxiv
DO - 10.1101/2025.08.09.669471
UR - https://doi.org/10.1101/2025.08.09.669471
AB - C9ORF72 is involved in multiple neuronal functions and a major factor in Amyotrophic Lateral Sclerosis, a fatal neurodegenerative disease. Pathogenicity is implemented through an intronic repeat expansion in the gene’s mRNA leader that produces long, repetitive RNA and dipeptides when translated through repeat associated non-canonical translation. The expanded repeat also suppresses transcription of the major transcript variant (Variant 2) which comprises 90% of the C9ORF72 levels in healthy cells, leading to an additional loss-of-function effect. Examining the sequence, structure, and ribosome occupancy of Variant 2’s mRNA leader in detail, we found that translation of C9ORF72 is tightly regulated through a multi-layered system. To deconvolute this system, we conducted a mutant screen and developed a method to evaluate the results quantitatively. We found that near-cognate start codons in all three frames, a start-stop element in frame 2, a uTranslon in frame 1, and secondary structures cooperate to keep baseline C9ORF72 translation low. Further, initiation at upstream near-cognate start codons reduces the impact of both the start-stop and the uTranslon, effectively buffering their repressive function and creating a feedforward loop. A strong secondary structure in the Variant 2-specific sequence further modulates initiation at all the elements. We hypothesize that this buffered repressor system has evolved to ensure reliable, noise-insensitive expression of this critical regulator of neuronal function. Finally, we used ADAR-based RNA editing of specific sites in Variant 2’s mRNA leader, increasing translation of the gene and providing a novel avenue to rescue the loss-of-function phenotype in disease.
SN - 2692-8205
ER -