RAN Translation at C9orf72-associated Repeat Expansions is Selectively Enhanced by the Integrated Stress Response

Overview

Journal Nat Commun

Specialty Biology

Date 2017 Dec 10

PMID 29222490

Citations 126

Authors

Katelyn M Green

M Rebecca Glineburg

Michael G Kearse

Brittany N Flores

Alexander E Linsalata

Stephen J Fedak

Aaron C Goldstrohm

Sami J Barmada

Peter K Todd

Affiliations

Soon will be listed here.

Abstract

Repeat-associated non-AUG (RAN) translation allows for unconventional initiation at disease-causing repeat expansions. As RAN translation contributes to pathogenesis in multiple neurodegenerative disorders, determining its mechanistic underpinnings may inform therapeutic development. Here we analyze RAN translation at GC repeat expansions that cause C9orf72-associated amyotrophic lateral sclerosis and frontotemporal dementia (C9RAN) and at CGG repeats that cause fragile X-associated tremor/ataxia syndrome. We find that C9RAN translation initiates through a cap- and eIF4A-dependent mechanism that utilizes a CUG start codon. C9RAN and CGG RAN are both selectively enhanced by integrated stress response (ISR) activation. ISR-enhanced RAN translation requires an eIF2α phosphorylation-dependent alteration in start codon fidelity. In parallel, both CGG and GC repeats trigger phosphorylated-eIF2α-dependent stress granule formation and global translational suppression. These findings support a model whereby repeat expansions elicit cellular stress conditions that favor RAN translation of toxic proteins, creating a potential feed-forward loop that contributes to neurodegeneration.

Citing Articles

intronic expansion identified by poly-glycine-arginine pathology increases Alzheimer's disease risk.

Nguyen L, Ajredini R, Guo S, Romano L, Tomas R, Bell L Proc Natl Acad Sci U S A. 2025; 122(7):e2416885122.

PMID: 39937857 PMC: 11848317. DOI: 10.1073/pnas.2416885122.

The role of cytosine methylation in regulating the topology and liquid-liquid phase separation of DNA G-quadruplexes.

Tsuruta M, Shil S, Taniguchi S, Kawauchi K, Miyoshi D Chem Sci. 2025; 16(10):4213-4225.

PMID: 39935503 PMC: 11808335. DOI: 10.1039/d4sc06959e.

Kaempferol enhances ER-mitochondria coupling and protects motor neurons from mitochondrial dysfunction and ER stress in C9ORF72-ALS.

Pilotto F, Smeele P, Scheidegger O, Diab R, Schobesberger M, Sierra-Delgado J Acta Neuropathol Commun. 2025; 13(1):21.

PMID: 39893487 PMC: 11787762. DOI: 10.1186/s40478-025-01927-y.

RNA dysregulation in neurodegenerative diseases.

Li Y, Sun S EMBO J. 2025; 44(3):613-638.

PMID: 39789319 PMC: 11790913. DOI: 10.1038/s44318-024-00352-6.

Alternative translation initiation produces synaptic organizer proteoforms with distinct localization and functions.

Lee P, Sun Y, Soares A, Fai C, Picciotto M, Guo J Mol Cell. 2024; 84(20):3967-3978.e8.

PMID: 39317199 PMC: 11490368. DOI: 10.1016/j.molcel.2024.08.032.

References

Pestova T, de Breyne S, Pisarev A, Abaeva I, Hellen C . eIF2-dependent and eIF2-independent modes of initiation on the CSFV IRES: a common role of domain II. EMBO J. 2008; 27(7):1060-72. PMC: 2323255. DOI: 10.1038/emboj.2008.49. View

Gao X, Wan J, Liu B, Ma M, Shen B, Qian S . Quantitative profiling of initiating ribosomes in vivo. Nat Methods. 2014; 12(2):147-53. PMC: 4344187. DOI: 10.1038/nmeth.3208. View

Wojciechowska M, Olejniczak M, Galka-Marciniak P, Jazurek M, Krzyzosiak W . RAN translation and frameshifting as translational challenges at simple repeats of human neurodegenerative disorders. Nucleic Acids Res. 2014; 42(19):11849-64. PMC: 4231732. DOI: 10.1093/nar/gku794. View

May S, Hornburg D, Schludi M, Arzberger T, Rentzsch K, Schwenk B . C9orf72 FTLD/ALS-associated Gly-Ala dipeptide repeat proteins cause neuronal toxicity and Unc119 sequestration. Acta Neuropathol. 2014; 128(4):485-503. PMC: 4159571. DOI: 10.1007/s00401-014-1329-4. View

Amick J, Ferguson S . C9orf72: At the intersection of lysosome cell biology and neurodegenerative disease. Traffic. 2017; 18(5):267-276. PMC: 5389918. DOI: 10.1111/tra.12477. View

Kearse M, Todd P . Repeat-associated non-AUG translation and its impact in neurodegenerative disease. Neurotherapeutics. 2014; 11(4):721-31. PMC: 4391382. DOI: 10.1007/s13311-014-0292-z. View

Skabkin M, Skabkina O, Dhote V, Komar A, Hellen C, Pestova T . Activities of Ligatin and MCT-1/DENR in eukaryotic translation initiation and ribosomal recycling. Genes Dev. 2010; 24(16):1787-801. PMC: 2922506. DOI: 10.1101/gad.1957510. View

Buchan J, Parker R . Eukaryotic stress granules: the ins and outs of translation. Mol Cell. 2010; 36(6):932-41. PMC: 2813218. DOI: 10.1016/j.molcel.2009.11.020. View

Rakotondrafara A, Hentze M . An efficient factor-depleted mammalian in vitro translation system. Nat Protoc. 2011; 6(5):563-71. DOI: 10.1038/nprot.2011.314. View

10.

Soto Rifo R, Ricci E, Decimo D, Moncorge O, Ohlmann T . Back to basics: the untreated rabbit reticulocyte lysate as a competitive system to recapitulate cap/poly(A) synergy and the selective advantage of IRES-driven translation. Nucleic Acids Res. 2007; 35(18):e121. PMC: 2094066. DOI: 10.1093/nar/gkm682. View

11.

Lee Y, Chen H, Peres J, Gomez-Deza J, Attig J, Stalekar M . Hexanucleotide repeats in ALS/FTD form length-dependent RNA foci, sequester RNA binding proteins, and are neurotoxic. Cell Rep. 2013; 5(5):1178-86. PMC: 3898469. DOI: 10.1016/j.celrep.2013.10.049. View

12.

Niblock M, Smith B, Lee Y, Sardone V, Topp S, Troakes C . Retention of hexanucleotide repeat-containing intron in C9orf72 mRNA: implications for the pathogenesis of ALS/FTD. Acta Neuropathol Commun. 2016; 4:18. PMC: 4766718. DOI: 10.1186/s40478-016-0289-4. View

13.

Rossi S, Serrano A, Gerbino V, Giorgi A, Di Francesco L, Nencini M . Nuclear accumulation of mRNAs underlies G4C2-repeat-induced translational repression in a cellular model of C9orf72 ALS. J Cell Sci. 2015; 128(9):1787-99. DOI: 10.1242/jcs.165332. View

14.

Mori K, Weng S, Arzberger T, May S, Rentzsch K, Kremmer E . The C9orf72 GGGGCC repeat is translated into aggregating dipeptide-repeat proteins in FTLD/ALS. Science. 2013; 339(6125):1335-8. DOI: 10.1126/science.1232927. View

15.

Kanekura K, Yagi T, Cammack A, Mahadevan J, Kuroda M, Harms M . Poly-dipeptides encoded by the C9ORF72 repeats block global protein translation. Hum Mol Genet. 2016; 25(9):1803-13. PMC: 4986334. DOI: 10.1093/hmg/ddw052. View

16.

Haeusler A, Donnelly C, Periz G, Simko E, Shaw P, Kim M . C9orf72 nucleotide repeat structures initiate molecular cascades of disease. Nature. 2014; 507(7491):195-200. PMC: 4046618. DOI: 10.1038/nature13124. View

17.

Das S, Ghosh R, Maitra U . Eukaryotic translation initiation factor 5 functions as a GTPase-activating protein. J Biol Chem. 2000; 276(9):6720-6. DOI: 10.1074/jbc.M008863200. View

18.

Jackson R, Hellen C, Pestova T . The mechanism of eukaryotic translation initiation and principles of its regulation. Nat Rev Mol Cell Biol. 2010; 11(2):113-27. PMC: 4461372. DOI: 10.1038/nrm2838. View

19.

Gami P, Murray C, Schottlaender L, Bettencourt C, De Pablo Fernandez E, Mudanohwo E . A 30-unit hexanucleotide repeat expansion in C9orf72 induces pathological lesions with dipeptide-repeat proteins and RNA foci, but not TDP-43 inclusions and clinical disease. Acta Neuropathol. 2015; 130(4):599-601. DOI: 10.1007/s00401-015-1473-5. View

20.

Boyce M, Bryant K, Jousse C, Long K, Harding H, Scheuner D . A selective inhibitor of eIF2alpha dephosphorylation protects cells from ER stress. Science. 2005; 307(5711):935-9. DOI: 10.1126/science.1101902. View