Long somatic DNA-repeat expansion drives neurodegeneration in Huntington disease

bioRxiv (Cold Spring Harbor Laboratory), Год журнала: 2024, Номер unknown

Опубликована: Май 20, 2024

Abstract Huntington Disease (HD) is a fatal genetic disease in which most striatal projection neurons (SPNs) degenerate. The central biological question about HD pathogenesis has been how the disease-causing DNA repeat expansion (CAG n ) huntingtin ( HTT gene leads to neurodegeneration after decades of apparent latency. Inherited alleles with longer CAG hasten onset; length this also changes over time, generating somatic mosaicism, and genes that regulate DNA-repeat stability can influence age-at-onset. To understand relationship between cell’s CAG-repeat its state, we developed single-cell method for measuring together genome-wide RNA expression. We found expands from 40-45 CAGs 100-500+ HD-vulnerable SPNs but not other cell types, these long expansions acquired at different times by individual SPNs. Surprisingly, 40 150 had no effect upon expression – 150-500+ shared profound gene-expression changes. These involved hundreds genes, escalated alongside further expansion, eroded positive then negative features neuronal identity, culminated senescence/apoptosis genes. Rates neuron loss across stages reflected rates entered biologically distorted state. Our results suggest repeats undergo quiet then, as they asynchronously cross high threshold, cause degenerate quickly asynchronously. conclude that, any moment course HD, have an innocuous (but unstable) gene, process almost all neuron’s life.

Язык: Английский

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Long somatic DNA-repeat expansion drives neurodegeneration in Huntington’s disease

Cell, Год журнала: 2025, Номер unknown

Опубликована: Янв. 1, 2025

Язык: Английский

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

Nature Genetics, Год журнала: 2025, Номер unknown

Опубликована: Янв. 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.

Язык: Английский

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Distinct mismatch-repair complex genes set neuronal CAG-repeat expansion rate to drive selective pathogenesis in HD mice

Cell, Год журнала: 2025, Номер unknown

Опубликована: Фев. 1, 2025

Highlights•Mismatch-repair genes drive striatal and cortical neuronal pathogenesis in HD mice•Linear rate of CAG expansion neurons is dependent on Msh3 Pms1•Somatic elicits repeat-length -threshold-dependent pathologies•Msh3 deficiency corrects synaptic, astrocytic, locomotor defects miceSummaryHuntington's disease (HD) modifiers include mismatch-repair (MMR) genes, but their connections to remain unclear. Here, we genetically tested 9 genome-wide association study (GWAS)/MMR mutant Huntingtin (mHtt) mice with 140 inherited repeats (Q140). Knockout (KO) encoding a distinct MMR complex either strongly (Msh3 Pms1) or moderately (Msh2 Mlh1) rescues phenotypes early onset medium-spiny (MSNs) late the neurons: somatic CAG-repeat expansion, transcriptionopathy, mHtt aggregation. ameliorates open-chromatin dysregulation Q140 neurons. Mechanistically, fast linear modal-CAG-repeat MSNs (8.8 repeats/month) drastically reduced stopped by mutants. Pms1 prevents aggregation keeping MSN length below 150. Importantly, mice. Thus, CAG-expansion rates HD-vulnerable elicit repeat-length/threshold-dependent, selective, progressive vivo.Graphical abstract

Язык: Английский

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Genetic modifiers of somatic expansion and clinical phenotypes in Huntington's disease reveal shared and tissue-specific effects

bioRxiv (Cold Spring Harbor Laboratory), Год журнала: 2024, Номер unknown

Опубликована: Июнь 18, 2024

ABSTRACT Huntington’s disease (HD), due to expansion of a CAG repeat in HTT , is representative growing number disorders involving somatically unstable short tandem repeats. We find that overlapping and distinct genetic modifiers clinical landmarks somatic blood DNA reveal an underlying complexity cell-type specificity the mismatch repair-related processes influence timing. Differential capture non-DNA-repair gene by multiple measures cognitive motor dysfunction argues additionally for pathogenic processes. Beyond trans modifiers, differential effects are also illustrated at 5’-UTR variant promotes without influencing HD, while, even after correcting uninterrupted length, synonymous sequence change end dramatically hastens onset signs increasing expansion. Our findings directly relevant therapeutic suppression HD related provide route define individual neuronal cell types contribute different phenotypes.

Язык: Английский

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Therapeutic validation of MMR-associated genetic modifiers in a human ex vivo model of Huntington disease

The American Journal of Human Genetics, Год журнала: 2024, Номер 111(6), С. 1165 - 1183

Опубликована: Май 14, 2024

The pathological huntingtin (HTT) trinucleotide repeat underlying Huntington disease (HD) continues to expand throughout life. Repeat length correlates both with earlier age at onset (AaO) and faster progression, making slowing its expansion an attractive therapeutic approach. Genome-wide association studies have identified candidate variants associated altered AaO many found in DNA mismatch repair (MMR)-associated genes. We examine whether lowering expression of these genes affects the rate human ex vivo models using HD iPSCs iPSC-derived striatal medium spiny neuron-enriched cultures. generated a stable CRISPR interference iPSC line which we can specifically efficiently lower gene from donor carrying over 125 CAG repeats. Lowering each member MMR complexes MutS (MSH2, MSH3, MSH6), MutL (MLH1, PMS1, PMS2, MLH3), LIG1 resulted characteristic deficiencies. Reduced MSH2, MLH1 slowed largest degree, while either or MLH3 it lesser degree. These effects were recapitulated cultures where factor was lowered. CRISPRi-mediated key levels feasibly achievable by current approaches able effectively slow HTT tract. highlight members family as potential targets pathogenic aim delay progression potentially other disorders exhibiting somatic instability.

Язык: Английский

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Msh3 and Pms1 Set Neuronal CAG-repeat Migration Rate to Drive Selective Striatal and Cortical Pathogenesis in HD Mice

Опубликована: Июль 13, 2024

SUMMARY Modifiers of Huntington’s disease (HD) include mismatch repair (MMR) genes; however, their underlying disease-altering mechanisms remain unresolved. Knockout (KO) alleles for 9 HD GWAS modifiers/MMR genes were crossed to the Q140 Huntingtin (mHtt) knock-in mice probe such mechanisms. Four KO strongly ( Msh3 and Pms1 ) or moderately Msh2 Mlh1 rescue a triad adult-onset, striatal medium-spiny-neuron (MSN)-selective phenotypes: somatic Htt DNA CAG-repeat expansion, transcriptionopathy, mHtt protein aggregation. Comparatively, cortex also exhibits an analogous, but later-onset, pathogenic that is -dependent. Remarkably, Q140/homozygous Msh3-KO lacks visible aggregates in brain, even at advanced ages (20-months). Moreover, -deficiency prevents synaptic marker loss, astrogliosis, locomotor impairment mice. Purified MSN nuclei exhibit highly linear age-dependent repeat expansion (i.e. migration), with modal-CAG increasing +8.8 repeats/month (R 2 =0.98). This rate reduced 2.3 0.3 heterozygous homozygous alleles, respectively. Our study defines thresholds below which there are no detectable nuclear neuropil aggregates. Mild transcriptionopathy can still occur stabilized 140-CAG repeats, majority transcriptomic changes due expansion. analysis reveals 479 expression levels correlated length MSNs. Thus, our mechanistically connects selective neuronal vulnerability HD, set migration drive repeat-length dependent pathogenesis; provides preclinical platform targeting these suppression across brain regions. One Sentence Summary genetic drivers sequential cortical pathogenesis by mediating vulnerable neurons.

Язык: Английский

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Accelerated epigenetic aging in Huntington’s disease involves polycomb repressive complex 1

Nature Communications, Год журнала: 2025, Номер 16(1)

Опубликована: Фев. 11, 2025

Abstract Loss of epigenetic information during physiological aging compromises cellular identity, leading to de-repression developmental genes. Here, we assessed the epigenomic landscape vulnerable neurons in two reference mouse models Huntington neurodegenerative disease (HD), using cell-type-specific multi-omics, including temporal analysis at three stages via FANS-CUT&Tag. We show accelerated genes HD striatal neurons, involving histone re-acetylation and depletion H2AK119 ubiquitination H3K27 trimethylation marks, which are catalyzed by polycomb repressive complexes 1 2 (PRC1 PRC2), respectively. further identify a PRC1-dependent subcluster bivalent transcription factors that is re-activated neurons. This mechanism likely involves progressive paralog switching between PRC1-CBX genes, promotes upregulation normally low-expressed PRC1-CBX2/4/8 isoforms alongside down-regulation predominant these cells (e.g., CBX6/7). Collectively, our data provide evidence for

Язык: Английский

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Antagonistic roles of canonical and Alternative-RPA in disease-associated tandem CAG repeat instability

Cell, Год журнала: 2023, Номер 186(22), С. 4898 - 4919.e25

Опубликована: Окт. 1, 2023

Язык: Английский

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Imaging brain glucose metabolism in vivo reveals propionate as a major anaplerotic substrate in pyruvate dehydrogenase deficiency

Cell Metabolism, Год журнала: 2024, Номер 36(6), С. 1394 - 1410.e12

Опубликована: Июнь 1, 2024

Язык: Английский

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