CGG repeats trigger translational frameshifts that generate aggregation-prone chimeric proteins

Wright, Shannon E.; Rodriguez, Caitlin M.; Monroe, Jeremy; Xing, Jiazheng; Krans, Amy; Flores, Brittany; Barsur, Venkatesha; Ivanova, Magdalena I.; Koutmou, Kristin S.; Barmada, Sami J.; Todd, Peter K.

doi:10.1093/nar/gkac626

Cited by 24 publications

(13 citation statements)

References 78 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Expression of either CGG or GGGGCC repeats in neurons is sufficient to elicit toxicity, which can serve as a proxy for gain-of-function associated neurodegeneration [30][31][32][33][34] . We therefore tested whether ectopic AAGGG or CCCTT repeat expression might elicit neurotoxicity.…”

Section: Translated Aaggg Repeat Products Are Detected In Canvas Pati...mentioning

confidence: 99%

AAGGG repeat expansions trigger RFC1-independent synaptic dysregulation in human CANVAS Neurons

Maltby,

Krans,

Grudzien

et al. 2023

Preprint

Self Cite

View full text Add to dashboard Cite

Cerebellar ataxia with neuropathy and vestibular areflexia syndrome (CANVAS) is a late onset, recessively inherited neurodegenerative disorder caused by biallelic, non-reference pentameric AAGGG(CCCTT) repeat expansions within the second intron of replication factor complex subunit 1 (RFC1). To investigate how these repeats cause disease, we generated CANVAS patient induced pluripotent stem cell (iPSC) derived neurons (iNeurons) and utilized calcium imaging and transcriptomic analysis to define repeat-elicited gain-of-function and loss-of-function contributions to neuronal toxicity. AAGGG repeat expansions do not alter neuronal RFC1 splicing, expression, or DNA repair pathway functions. In reporter assays, AAGGG repeats are translated into pentapeptide repeat proteins that selectively accumulate in CANVAS patient brains. However, neither these proteins nor repeat RNA foci were detected in iNeurons, and overexpression of these repeats in isolation did not induce neuronal toxicity. CANVAS iNeurons exhibit defects in neuronal development and diminished synaptic connectivity that is rescued by CRISPR deletion of a single expanded allele. These phenotypic deficits were not replicated by knockdown of RFC1 in control neurons and were not rescued by ectopic expression of RFC1. These findings support a repeat-dependent but RFC1-independent cause of neuronal dysfunction in CANVAS, with important implications for therapeutic development in this currently untreatable condition.SummaryHuman CANVAS neurons exhibit transcriptional and functional synaptic defects that are corrected by heterozygous repeat deletion but are independent of the gene within which they reside—RFC1.

show abstract

Section: Translated Aaggg Repeat Products Are Detected In Canvas Pati...mentioning

confidence: 99%

AAGGG repeat expansions trigger RFC1-independent synaptic dysregulation in human CANVAS Neurons

Maltby,

Krans,

Grudzien

et al. 2023

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…Thus, two or more moderately infrequent codons repeated back-to-back would deplete their cognate tRNA from the pool and ultimately act as a rare "hungry" codon. Tandem repeats have been shown to induce ribosomal frameshifting insitu in E. coli (49)(50)(51), are responsible for the frameshifting associated with many human diseases (52,53), as well as translational-pausing involved in the synthesis of amino acids and polyamines (54,55). Dividing the waiting A-site codon frequency by the number of times it occurs within some upstream window of a given length would give a more nuanced measure of how "hungry" a rare codon is.…”

Section: Future Improvementsmentioning

confidence: 99%

Programmed ribosomal frameshifts, and how to find them

McNair

Szűcs

Edwards

et al. 2023

Preprint

View full text Add to dashboard Cite

One of the stranger phenomena that can occur during gene translation is where, as a ribosome reads along the mRNA, various cellular and molecular properties contribute to stalling the ribosome on a slippery sequence, shifting the ribosome into one of the other two alternate reading frames. The alternate frame has different codons, so different amino acids are added to the peptide chain, but more importantly, the original stop codon is no longer in-frame, so the ribosome can bypass the stop codon and continue to translate the codons past it. This produces a longer version of the protein, a fusion of the original in-frame amino acids, followed by all the alternate frame amino acids. There is currently no automated software to predict the occurrence of these programmed ribosomal frameshifts (PRF), and they are currently only identified by manual curation. Here we present the first machine-learning based method to detect and predict the presence of PRFs in all types of coding genes and taxa with an accuracy exceding 90%.

show abstract

“…Protein production from expanded nucleotide repeats is initiated at different near-cognate start codons in diverse reading frames. The resultant toxic proteins contain repeated amino acid tracts, such as polyglycine (FMRpolyG), polyalanine (FMRpolyA), polyarginine (FMRpolyR), or hybrids of them produced as a result of frameshifting (Todd et al , 2013; Wright et al , 2022; Glineburg et al , 2018; Kearse et al , 2016). Notably, the open reading frame for FMRP starting from the AUG codon downstream to the repeats is canonically synthesized.…”

Section: Introductionmentioning

confidence: 99%

Insufficiency of 40S ribosomal proteins, RPS26 and RPS25, negatively affects biosynthesis of polyglycine-containing proteins in fragile-X associated conditions

Tutak,

Broniarek,

Zielezinski

et al. 2024

Preprint

View full text Add to dashboard Cite

Expansion of CGG repeats (CGGexp) in the 5′ untranslated region (5′UTR) of the FMR1 gene underlies the fragile X-associated conditions including tremor/ataxia syndrome (FXTAS), a late-onset neurodegenerative disease. One pathomechanism of FXTAS is the repeat-associated non-AUG-initiated (RAN) translation of CGG repeats of mutant FMR1 mRNA, resulting in production of FMRpolyG, a toxic protein containing long polyglycine tract. To identify novel modifiers of RAN translation we used an RNA-tagging system and mass spectrometry-based screening. It revealed proteins enriched on CGGexp-containing FMR1 RNA in cellulo, including a ribosomal protein RPS26, a component of the 40S subunit. We demonstrated that RPS26, together with its chaperone TSR2, modulates FMRpolyG production and its toxicity. We also found that the number of proteins produced via RPS26-sensitive translation was limited, and 5′UTRs of mRNAs encoding these proteins were guanosine and cytosine-rich. Moreover, the silencing of another component of the 40S subunit, the ribosomal protein RPS25, also induced repression of FMRpolyG biosynthesis. Results of this study suggest that the composition of the 40S subunit plays important role in noncanonical CGGexp-related RAN translation.

show abstract

CGG repeats trigger translational frameshifts that generate aggregation-prone chimeric proteins

Cited by 24 publications

References 78 publications

AAGGG repeat expansions trigger RFC1-independent synaptic dysregulation in human CANVAS Neurons

AAGGG repeat expansions trigger RFC1-independent synaptic dysregulation in human CANVAS Neurons

Programmed ribosomal frameshifts, and how to find them

Insufficiency of 40S ribosomal proteins, RPS26 and RPS25, negatively affects biosynthesis of polyglycine-containing proteins in fragile-X associated conditions

Contact Info

Product

Resources

About