Aberrant alternative splicing and extracellular matrix gene expression in mouse models of myotonic dystrophy

Du, Hongqing; Cline, Melissa; Osborne, Robert J.; Tuttle, Daniel L.; Clark, Tyson A.; Donohue, John P.; Hall, Megan P.; Shiue, Lily; Swanson, Maurice S.; Thornton, Charles A.; Ares, Manuel

doi:10.1038/nsmb.1720

Cited by 300 publications

(457 citation statements)

References 64 publications

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“…RNAs harboring a long stretch of repeats are thought to fold into stable structures and sequester RNA binding proteins, which, in turn, sets off a molecular cascade leading to neurodegeneration (7). In myotonic dystrophy, sequestration and functional disruption of the muscleblind-like family of RNA binding proteins are associated with specific splicing and expression changes in affected tissues (5,(8)(9)(10)(11)(12).Sequestration of one or more RNA binding proteins into pathological RNA foci has also been proposed in ALS/FTD linked to C9orf72 expansion (1, 13-16). It is anticipated, but has not been demonstrated, that sequestration of RNA binding proteins into expanded GGGGCC RNA foci may lead to major RNA processing alterations as in myotonic dystrophy.…”

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confidence: 99%

Targeted degradation of sense and antisense C9orf72 RNA foci as therapy for ALS and frontotemporal degeneration

Lagier‐Tourenne

Baughn

Rigo

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

521

573

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Expanded hexanucleotide repeats in the chromosome 9 open reading frame 72 (C9orf72) gene are the most common genetic cause of ALS and frontotemporal degeneration (FTD). Here, we identify nuclear RNA foci containing the hexanucleotide expansion (GGGGCC) in patient cells, including white blood cells, fibroblasts, glia, and multiple neuronal cell types (spinal motor, cortical, hippocampal, and cerebellar neurons). RNA foci are not present in sporadic ALS, familial ALS/FTD caused by other mutations (SOD1, TDP-43, or tau), Parkinson disease, or nonneurological controls. Antisense oligonucleotides (ASOs) are identified that reduce GGGGCC-containing nuclear foci without altering overall C9orf72 RNA levels. By contrast, siRNAs fail to reduce nuclear RNA foci despite marked reduction in overall C9orf72 RNAs. Sustained ASO-mediated lowering of C9orf72 RNAs throughout the CNS of mice is demonstrated to be well tolerated, producing no behavioral or pathological features characteristic of ALS/FTD and only limited RNA expression alterations. Genome-wide RNA profiling identifies an RNA signature in fibroblasts from patients with C9orf72 expansion. ASOs targeting sense strand repeat-containing RNAs do not correct this signature, a failure that may be explained, at least in part, by discovery of abundant RNA foci with C9orf72 repeats transcribed in the antisense (GGCCCC) direction, which are not affected by sense strand-targeting ASOs. Taken together, these findings support a therapeutic approach by ASO administration to reduce hexanucleotide repeat-containing RNAs and raise the potential importance of targeting expanded RNAs transcribed in both directions.E xpanded hexanucleotide repeats in the first intron of the chromosome 9 open reading frame 72 (C9orf72) gene were recently identified (1, 2) as the most common genetic cause of ALS, frontotemporal degeneration (FTD), or concomitant ALS/ FTD (3, 4). The mechanisms by which the expanded repeats cause neurodegeneration are unknown, but leading candidate mechanisms are RNA-mediated toxicity, loss of the C9orf72 gene function (from reduced C9orf72 produced by the allele with the expansion), or a combination of the two.RNA-mediated toxicity from nucleotide repeat expansion was initially described for CUG expansion in the RNA encoded by the DMPK gene in myotonic muscular dystrophy (5). A consensus view is that RNA toxicity plays a crucial role in a variety of repeat expansion disorders (6). A hallmark of these disorders is the accumulation of expanded transcripts into nuclear RNA foci (7). RNAs harboring a long stretch of repeats are thought to fold into stable structures and sequester RNA binding proteins, which, in turn, sets off a molecular cascade leading to neurodegeneration (7). In myotonic dystrophy, sequestration and functional disruption of the muscleblind-like family of RNA binding proteins are associated with specific splicing and expression changes in affected tissues (5,(8)(9)(10)(11)(12).Sequestration of one or more RNA binding proteins into pathological RNA foci has ...

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confidence: 99%

Targeted degradation of sense and antisense C9orf72 RNA foci as therapy for ALS and frontotemporal degeneration

Lagier‐Tourenne

Baughn

Rigo

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

521

573

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“…38 Several studies have addressed the effects of loss of MBNL1 at the molecular and the phenotypical level. 18,23,32,39 Du et al 32 compared a mouse model expressing a (CUG) n expansion with a mbnl1 knockout mouse. RNA expression was grossly disturbed with mainly splicing defects.…”

Section: Discussionmentioning

confidence: 99%

“…An estimated 480% of these effects were due to loss of MBNL1 function. 32 Jog et al 30 demonstrated a gene dosage effect: the splicing activity of MBNL1 is dependent on the number of active gene copies. The splicing pattern shifted from the adult to the fetal pattern concomitant with the rate of loss in MBNL1 activity.…”

Section: Discussionmentioning

confidence: 99%

Identification of variants in MBNL1 in patients with a myotonic dystrophy-like phenotype

et al. 2016

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The myotonic dystrophies (DMs) are the most common inherited muscular disorders in adults. In most of the cases, the disease is caused by (CTG) n /(CCTG) n repeat expansions (EXPs) in non-coding regions of the genes DMPK (dystrophia myotonica-protein kinase) and CNBP (CCHC-type zinc-finger nucleic acid-binding protein). The EXP is transcribed into mutant RNAs, which provoke a common pathomechanism that is characterized by misexpression and mis-splicing. In this study, we screened 138 patients with typical clinical features of DM being negative for EXP in the known genes. We sequenced DMPK and CNBPassociated with DM, as well as CELF1 (CUGBP, Elav-like family member 1) and MBNL1 (muscleblind-like splicing regulator 1) -associated with the pathomechanism of DM, for pathogenic variants, addressing the question whether defects in other genes could cause a DM-like phenotype. We identified variants in three unrelated patients in the MBNL1 gene, two of them were heterozygous missense mutations and one an in-frame deletion of three amino acids. The variants were located in different conserved regions of the protein. The missense mutations were classified as potentially pathogenic by prediction tools. Analysis of MBNL1 splice target genes was carried out for one of the patients using RNA from peripheral blood leukocytes (PBL). Analysis of six genes known to show mis-splicing in the skeletal muscle gave no informative results on the effect of this variant when tested in PBL. The association of these variants with the DM phenotype therefore remains unconfirmed, but we hope that in view of the key role of MBNL1 in DM pathogenesis our observations may foster further studies in this direction.

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“…Alternative splicing is severely misregulated in DM1 patients and in HSA LR mice (11,12). We analyzed alternative splicing patterns in transcripts of two direct Mbnl1 targets: the muscle sarcoplasmic/endoplasmic reticulum Ca 2þ ATPase (Serca1) and fast skeletal muscle troponin T (Tnnt3).…”

Section: Abp1 Reversed Missplicing and Muscle Histopathology In A Dm1mentioning

confidence: 99%

“…CTGrepeat expression in mice caused misregulation of at least 156 alternative splicing events. Of these, 128 also occurred in Mbnl1 knockout animals (9)(10)(11)(12). The splicing factor CUG-binding protein 1 (CUGBP1) is another key component in the development of DM1 phenotypes.…”

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confidence: 99%

In vivo discovery of a peptide that prevents CUG–RNA hairpin formation and reverses RNA toxicity in myotonic dystrophy models

Garcia-Lopez

Llamusí

Orzáez

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Myotonic dystrophy type 1 (DM1) is caused by the expansion of noncoding CTG repeats in the dystrophia myotonica-protein kinase gene. Mutant transcripts form CUG hairpins that sequester RNAbinding factors into nuclear foci, including Muscleblind-like-1 protein (MBNL1), which regulate alternative splicing and gene expression. To identify molecules that target toxic CUG transcripts in vivo, we performed a positional scanning combinatorial peptide library screen using a Drosophila model of DM1. The screen identified a D-amino acid hexapeptide (ABP1) that reduced CUG foci formation and suppressed CUG-induced lethality and muscle degeneration when administered orally. Transgenic expression of natural, L-amino acid ABP1 analogues reduced CUG-induced toxicity in fly eyes and muscles. Furthermore, ABP1 reversed muscle histopathology and splicing misregulation of MBNL1 targets in DM1 model mice. In vitro, ABP1 bound to CUG hairpins and induced a switch to a single-stranded conformation. Our findings demonstrate that ABP1 shows antimyotonic dystrophy activity by targeting the core of CUG toxicity.disease model | drug discovery | non-coding RNA disease | medicinal chemistry | RNA secondary structure M yotonic dystrophy type 1 (DM1, OMIM #160900) is an autosomal dominant disease caused by the expansion of a CTG trinucleotide repeat in the 3′ untranslated region (UTR) of the dystrophia myotonica-protein kinase (DMPK) gene. Characteristic symptoms include myotonia, progressive muscle wasting, and cardiac conduction defects, among other systemic manifestations. The molecular mechanisms underlying DM1 pathogenesis are complex and affect a large number of cellular processes (1). However, most data suggest that the main triggering event is a toxic gain-of-function of the expanded CUG RNA. CUG-repeat expansions form double-stranded hairpins that are retained as inclusions within the nucleus. These hairpins recruit a number of transcription and splicing factors, including Muscleblind-like 1 (MBNL1) (2-6). Sequestration of MBNL1 originates a loss of function, which plays a key role in the development of DM1 symptoms. Mbnl1 knockout mice reproduced typical features of DM1, and overexpression of Mbnl1 in a mouse model that expressed CTG repeats reversed these phenotypes (7,8). CTGrepeat expression in mice caused misregulation of at least 156 alternative splicing events. Of these, 128 also occurred in Mbnl1 knockout animals (9-12). The splicing factor CUG-binding protein 1 (CUGBP1) is another key component in the development of DM1 phenotypes. CUGBP1 antagonizes MBNL1 activity in the regulated use of alternative exons in a number of transcripts and is abnormally upregulated in patients with DM1, further contributing to splicing misregulation (13-15).Mahadevan et al. provided the first in vivo proof-of-principle for a therapeutic strategy based on ablating toxic RNA molecules in DM1 (16). They demonstrated that expanded CTG-induced effects could be reverted if CTG-repeat transgene expression was interrupted in a DM1 mouse model. Several ...

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Aberrant alternative splicing and extracellular matrix gene expression in mouse models of myotonic dystrophy

Cited by 300 publications

References 64 publications

Targeted degradation of sense and antisense C9orf72 RNA foci as therapy for ALS and frontotemporal degeneration

Targeted degradation of sense and antisense C9orf72 RNA foci as therapy for ALS and frontotemporal degeneration

Identification of variants in MBNL1 in patients with a myotonic dystrophy-like phenotype

In vivo discovery of a peptide that prevents CUG–RNA hairpin formation and reverses RNA toxicity in myotonic dystrophy models

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