In vivo CRISPR–Cas9 genome editing in mice identifies genetic modifiers of somatic CAG repeat instability in Huntington’s disease

Nature Genetics, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 22, 2025

Huntington's disease, one of more than 50 inherited repeat expansion disorders1, is a dominantly neurodegenerative disease caused by CAG in HTT2. Inherited length the primary determinant age onset, with human genetic studies underscoring that driven length-dependent propensity to further expand brain3–9. Routes slowing somatic expansion, therefore, hold promise for disease-modifying therapies. Several DNA repair genes, notably mismatch pathway, modify mouse models10. To identify novel modifiers we used CRISPR–Cas9 editing knock-in mice enable vivo screening expansion-modifier candidates at scale. This included testing onset modifier genes emerging from genome-wide association as well interactions between providing insight into pathways underlying and potential therapeutic targets. A strategy identifies new contribute disease.

Language: Английский

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Huntington’s disease gene variants past a certain size poison select cells

The Transmitter, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

Language: Английский

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Therapeutic targeting of mismatch repair proteins in triplet repeat expansion diseases

DNA repair, Journal Year: 2025, Volume and Issue: 147, P. 103817 - 103817

Published: Feb. 15, 2025

Language: Английский

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PMS2 has both pro-mutagenic and anti-mutagenic effects on repeat instability in the Repeat Expansion Diseases

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2024, Volume and Issue: unknown

Published: Aug. 13, 2024

Abstract Genome Wide Association studies (GWAS) have implicated PMS2 as a modifier of somatic expansion in Huntington’s disease (HD), one >45 known Repeat Expansion Diseases (REDs). is subunit the MutLα complex, major component mismatch repair (MMR) system, pathway that involved generation expansions many different REDs. However, while MLH3, second MutL MutLγ, required for all expansions, has been shown to protect against some model systems but drive others. To better understand PMS2’s behavior, we compared effect loss tissues an HD mouse (CAG/CTG repeats) and Fragile X-related disorders (FXDs), result from CGG/CCG repeat expansion. Mice heterozygous Pms2 show increased most expansion-prone both models. null mice repeats decreased Thus, previously reported differences effects do not reflect fundamentally roles played by REDs, rather paradoxical cellular contexts. These findings important implications only mechanism development therapeutic approaches reduce pathology generated expansion, also our understanding normal MMR.

Language: Английский

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When repetita no-longer iuvant: somatic instability of the CAG triplet in Huntington’s disease

Nucleic Acids Research, Journal Year: 2024, Volume and Issue: unknown

Published: Dec. 14, 2024

Abstract Trinucleotide repeats in DNA exhibit a dual nature due to their inherent instability. While rapid expansion can diversify gene expression during evolution, exceeding certain threshold lead diseases such as Huntington’s disease (HD), neurodegenerative condition, triggered by >36 C–A–G exon 1 of the Huntingtin gene. Notably, discovery somatic instability (SI) tract allows these mutations, inherited from an affected parent, further expand throughout patient’s lifetime, resulting mosaic brain with specific neurons exhibiting variable and often extreme CAG lengths, ultimately leading death. Genome-wide association studies have identified genetic variants—both cis trans, including mismatch repair modifiers—that modulate SI, shown blood cells, influence HD’s age onset. This review will explore evidence for SI HD its role pathogenesis, well therapeutic implications findings. We conclude emphasizing urgent need reliable methods quantify diagnostic prognostic purposes.

Language: Английский

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Suppression of Huntington's Disease Somatic Instability by Transcriptional Repression and Direct CAG Repeat Binding

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2024, Volume and Issue: unknown

Published: Nov. 4, 2024

Abstract Huntington’s disease (HD) arises from a CAG expansion in the huntingtin ( HTT ) gene beyond critical threshold. A major thrust of current HD therapeutic development is lowering levels mutant mRNA (m and protein (mHTT) with aim reducing toxicity these product(s). Human genetic data also support key role for somatic instability (SI) ’s repeat – whereby it lengthens age specific cell types as driver motor dysfunction onset. Thus, an attractive therapy would address both mHTT SI, but to date relationship between SI remains unexplored. Here, we investigated multiple therapeutically-relevant HTT-lowering modalities establish knock-in mice. We find that repressing transcription Htt provides robust protection using diverse pharmacological approaches (antisense oligonucleotides, CRISPR-Cas9 genome editing, Lac repressor, virally delivered zinc finger transcriptional repressor proteins, ZFPs). However, small interfering RNA (siRNA), potent treatment, lowers without influencing normal mice lacking 50% total levels, suggesting per se , do not modulate trans . Remarkably, modified ZFPs bind m locus, lack repressive domain, robustly protect despite or levels. These results have important implications HD, they suggest DNA-targeted treatments may significant advantages compared other approaches, interaction DNA-binding HTT’ s repeats provide while sparing expression.

Language: Английский

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Navigating triplet repeats sequencing: concepts, methodological challenges and perspective for Huntington’s disease

Nucleic Acids Research, Journal Year: 2024, Volume and Issue: unknown

Published: Dec. 2, 2024

The accurate characterization of triplet repeats, especially the overrepresented CAG is increasingly relevant for several reasons. First, germline expansion repeats above a gene-specific threshold causes multiple neurodegenerative disorders; instance, Huntington's disease (HD) triggered by >36 in huntingtin (HTT) gene. Second, extreme expansions up to 800 have been found specific cell types affected disease. Third, synonymous single nucleotide variants within repeat stretch influence age onset. Thus, new sequencing-based protocols that profile both length and exact sequence are crucial. Various strategies enrich target gene over background, along with sequencing platforms bioinformatic pipelines, under development. This review discusses concepts, challenges, methodological opportunities analyzing using HD as case study. Starting traditional approaches, we will explore how methods evolved meet increasing scientific demands. We also highlight experimental aiming provide guide diagnostic therapeutic purposes.

Language: Английский

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Genomic characterization of Huntington’s disease genetic modifiers informs drug target tractability

Brain Communications, Journal Year: 2024, Volume and Issue: 7(1)

Published: Dec. 24, 2024

Huntington's disease is caused by a CAG repeat in the

Language: Английский

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