Antisense oligonucleotide-based treatment of retinitis pigmentosa caused by mutations in USH2A exon 13

AbstractMutations in USH2A, encoding usherin, are the most common cause of syndromic and non-syndromic retinitis pigmentosa (RP). The two founder mutations in exon 13 (c.2299delG and c.2276G>T) collectively account for ~34% of USH2A-associated RP cases. Skipping of exon 13 from the USH2A transcript during pre-mRNA splicing presents a potential treatment modality in which the resulting transcript is predicted to encode a slightly shortened usherin protein. Morpholino-induced skipping of ush2a exon 13 in larvae of the previously published ush2a exon 13 zebrafish mutant resulted in the production of usherinΔexon13 and completely restored retinal function. RNA antisense oligonucleotides were investigated for their potential to specifically induce human USH2A exon 13 skipping. Lead candidate QR-421a induced dose-dependent exon 13 skipping in iPSC-derived photoreceptor precursors from a patient homozygous for the USH2A c.2299delG mutation. Intravitreal delivery of QR-421a in non-human primates showed that QR-421a penetrates the retinal outer nuclear layer and induces detectable levels of exon 13 skipping until at least 3 months post injection. In conclusion, QR-421a-induced exon skipping proves to be a highly promising treatment for RP caused by mutations in exon 13 of the USH2A gene.

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Proof-of-Concept: Antisense Oligonucleotide Mediated Skipping of Fibrillin-1 Exon 52

International Journal of Molecular Sciences ◽

10.3390/ijms22073479 ◽

2021 ◽

Vol 22 (7) ◽

pp. 3479

Author(s):

Jessica M. Cale ◽

Kane Greer ◽

Sue Fletcher ◽

Steve D. Wilton

Keyword(s):

Antisense Oligonucleotide ◽

Antisense Oligonucleotides ◽

Exon Skipping ◽

Mrna Splicing ◽

Immunofluorescent Staining ◽

Proof Of Concept ◽

Connective Tissue Disorders ◽

Fibrillin 1 ◽

Healthy Control

Marfan syndrome is one of the most common dominantly inherited connective tissue disorders, affecting 2–3 in 10,000 individuals, and is caused by one of over 2800 unique FBN1 mutations. Mutations in FBN1 result in reduced fibrillin-1 expression, or the production of two different fibrillin-1 monomers unable to interact to form functional microfibrils. Here, we describe in vitro evaluation of antisense oligonucleotides designed to mediate exclusion of FBN1 exon 52 during pre-mRNA splicing to restore monomer homology. Antisense oligonucleotide sequences were screened in healthy control fibroblasts. The most effective sequence was synthesised as a phosphorodiamidate morpholino oligomer, a chemistry shown to be safe and effective clinically. We show that exon 52 can be excluded in up to 100% of FBN1 transcripts in healthy control fibroblasts transfected with PMO52. Immunofluorescent staining revealed the loss of fibrillin 1 fibres with ~50% skipping and the subsequent re-appearance of fibres with >80% skipping. However, the effect of exon skipping on the function of the induced fibrillin-1 isoform remains to be explored. Therefore, these findings demonstrate proof-of-concept that exclusion of an exon from FBN1 pre-mRNA can result in internally truncated but identical monomers capable of forming fibres and lay a foundation for further investigation to determine the effect of exon skipping on fibrillin-1 function.

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Myoblasts and macrophages are required for therapeutic morpholino antisense oligonucleotide delivery to dystrophic muscle

Nature Communications ◽

10.1038/s41467-017-00924-7 ◽

2017 ◽

Vol 8 (1) ◽

Cited By ~ 18

Author(s):

James S. Novak ◽

Marshall W. Hogarth ◽

Jessica F. Boehler ◽

Marie Nearing ◽

Maria C. Vila ◽

...

Keyword(s):

Clinical Trials ◽

Duchenne Muscular Dystrophy ◽

Antisense Oligonucleotide ◽

Antisense Oligonucleotides ◽

Therapeutic Strategy ◽

Exon Skipping ◽

Efficient Production ◽

Dystrophic Muscle ◽

Oligonucleotide Delivery ◽

Dystrophin Protein

Abstract Exon skipping is a promising therapeutic strategy for Duchenne muscular dystrophy (DMD), employing morpholino antisense oligonucleotides (PMO-AO) to exclude disruptive exons from the mutant DMD transcript and elicit production of truncated dystrophin protein. Clinical trials for PMO show variable and sporadic dystrophin rescue. Here, we show that robust PMO uptake and efficient production of dystrophin following PMO administration coincide with areas of myofiber regeneration and inflammation. PMO localization is sustained in inflammatory foci where it enters macrophages, actively differentiating myoblasts and newly forming myotubes. We conclude that efficient PMO delivery into muscle requires two concomitant events: first, accumulation and retention of PMO within inflammatory foci associated with dystrophic lesions, and second, fusion of PMO-loaded myoblasts into repairing myofibers. Identification of these factors accounts for the variability in clinical trials and suggests strategies to improve this therapeutic approach to DMD.

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Zebrafish as a Model to Evaluate a CRISPR/Cas9-Based Exon Excision Approach as a Future Treatment Option for EYS-Associated Retinitis Pigmentosa

International Journal of Molecular Sciences ◽

10.3390/ijms22179154 ◽

2021 ◽

Vol 22 (17) ◽

pp. 9154

Author(s):

Renske Schellens ◽

Erik de Vrieze ◽

Pam Graave ◽

Sanne Broekman ◽

Kerstin Nagel-Wolfrum ◽

...

Keyword(s):

Retinitis Pigmentosa ◽

Single Molecule ◽

Therapeutic Potential ◽

Outer Nuclear Layer ◽

Exon Skipping ◽

Retinal Disease ◽

Loss Of Function ◽

Zebrafish Model ◽

Reading Frame ◽

Future Treatment

Retinitis pigmentosa (RP) is an inherited retinal disease (IRD) with an overall prevalence of 1 in 4000 individuals. Mutations in EYS (Eyes shut homolog) are among the most frequent causes of non-syndromic autosomal recessively inherited RP and act via a loss-of-function mechanism. In light of the recent successes for other IRDs, we investigated the therapeutic potential of exon skipping for EYS-associated RP. CRISPR/Cas9 was employed to generate zebrafish from which the region encompassing the orthologous exons 37-41 of human EYS (eys exons 40-44) was excised from the genome. The excision of these exons was predicted to maintain the open reading frame and to result in the removal of exactly one Laminin G and two EGF domains. Although the eysΔexon40-44 transcript was found at levels comparable to wild-type eys, and no unwanted off-target modifications were identified within the eys coding sequence after single-molecule sequencing, EysΔexon40-44 protein expression could not be detected. Visual motor response experiments revealed that eysΔexon40-44 larvae were visually impaired and histological analysis revealed a progressive degeneration of the retinal outer nuclear layer in these zebrafish. Altogether, the data obtained in our zebrafish model currently provide no indications for the skipping of EYS exons 37-41 as an effective future treatment strategy for EYS-associated RP.

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New Approach for Antisense Oligonucleotide-Mediated Exon Skipping in Duchenne Muscular Dystrophy

Journal of Advanced Computational Intelligence and Intelligent Informatics ◽

10.20965/jaciii.2012.p0521 ◽

2012 ◽

Vol 16 (4) ◽

pp. 521-526

Author(s):

Yoshitsugu Aoki ◽

◽

Tetsuya Nagata ◽

Shin’ichi Takeda

Keyword(s):

Duchenne Muscular Dystrophy ◽

Muscular Dystrophy ◽

Antisense Oligonucleotide ◽

Antisense Oligonucleotides ◽

Exon Skipping ◽

New Approach ◽

Reading Frame ◽

Promising Therapeutic Approach ◽

Dmd Gene ◽

Dystrophin Protein

Duchenne Muscular Dystrophy (DMD) is a lethalmuscle disorder characterized by mutations in the DMD gene. These mutations primarily disrupt the reading frame, resulting in the absence of functional dystrophin protein. Exon skipping, which involves the use of antisense oligonucleotides is a promising therapeutic approach for DMD, and clinical trials on exon skipping are currently underway in DMD patients. Recently, stable and less-toxic antisense oligonucleotides with higher efficacy have been developed in mouse and dog models of DMD. This review highlights a new approach for antisense oligonucleotide-based therapeutics for DMD, particularly for exon skipping-based methods.

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The administration of antisense oligonucleotide golodirsen reduces pathological regeneration in patients with Duchenne muscular dystrophy

Acta Neuropathologica Communications ◽

10.1186/s40478-020-01106-1 ◽

2021 ◽

Vol 9 (1) ◽

Author(s):

Dominic Scaglioni ◽

Francesco Catapano ◽

Matthew Ellis ◽

Silvia Torelli ◽

Darren Chambers ◽

...

Keyword(s):

Duchenne Muscular Dystrophy ◽

Muscular Dystrophy ◽

Antisense Oligonucleotide ◽

De Novo ◽

Exon Skipping ◽

Significant Negative Correlation ◽

Entire Cohort ◽

Associated Proteins ◽

Analysis Platform ◽

Dystrophin Protein

AbstractDuring the last decade, multiple clinical trials for Duchenne muscular dystrophy (DMD) have focused on the induction of dystrophin expression using different strategies. Many of these trials have reported a clear increase in dystrophin protein following treatment. However, the low levels of the induced dystrophin protein have raised questions on its functionality. In our present study, using an unbiased, high-throughput digital image analysis platform, we assessed markers of regeneration and levels of dystrophin associated protein via immunofluorescent analysis of whole muscle sections in 25 DMD boys who received 48-weeks treatment with exon 53 skipping morpholino antisense oligonucleotide (PMO) golodirsen. We demonstrate that the de novo dystrophin induced by exon skipping with PMO golodirsen is capable of conferring a histological benefit in treated patients with an increase in dystrophin associated proteins at the dystrophin positive regions of the sarcolemma in post-treatment biopsies. Although 48 weeks treatment with golodirsen did not result in a significant change in the levels of fetal/developmental myosins for the entire cohort, there was a significant negative correlation between the amount of dystrophin and levels of regeneration observed in different biopsy samples. Our results provide, for the first time, evidence of functionality of induced dystrophin following successful therapeutic intervention in the human.

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Personalized Development of Antisense Oligonucleotides for Exon Skipping Restores Type XVII Collagen Expression in Junctional Epidermolysis Bullosa

International Journal of Molecular Sciences ◽

10.3390/ijms22073326 ◽

2021 ◽

Vol 22 (7) ◽

pp. 3326

Author(s):

Michael Ablinger ◽

Thomas Lettner ◽

Nicole Friedl ◽

Hannah Potocki ◽

Theresa Palmetzhofer ◽

...

Keyword(s):

Epidermolysis Bullosa ◽

Antisense Oligonucleotides ◽

Exon Skipping ◽

Junctional Epidermolysis Bullosa ◽

Reading Frame ◽

Collagen Expression ◽

Promising Tool ◽

Mucous Membranes ◽

Personalized Approach ◽

Xvii Collagen

Intermediate junctional epidermolysis bullosa caused by mutations in the COL17A1 gene is characterized by the frequent development of blisters and erosions on the skin and mucous membranes. The rarity of the disease and the heterogeneity of the underlying mutations renders therapy developments challenging. However, the high number of short in-frame exons facilitates the use of antisense oligonucleotides (AON) to restore collagen 17 (C17) expression by inducing exon skipping. In a personalized approach, we designed and tested three AONs in combination with a cationic liposomal carrier for their ability to induce skipping of COL17A1 exon 7 in 2D culture and in 3D skin equivalents. We show that AON-induced exon skipping excludes the targeted exon from pre-mRNA processing, which restores the reading frame, leading to the expression of a slightly truncated protein. Furthermore, the expression and correct deposition of C17 at the dermal–epidermal junction indicates its functionality. Thus, we assume AON-mediated exon skipping to be a promising tool for the treatment of junctional epidermolysis bullosa, particularly applicable in a personalized manner for rare genotypes.

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In vivocomparison of 2′-O-methyl phosphorothioate and morpholino antisense oligonucleotides for Duchenne muscular dystrophy exon skipping

The Journal of Gene Medicine ◽

10.1002/jgm.1288 ◽

2009 ◽

Vol 11 (3) ◽

pp. 257-266 ◽

Cited By ~ 128

Author(s):

Hans A. Heemskerk ◽

Christa L. de Winter ◽

Sjef J. de Kimpe ◽

Petra van Kuik-Romeijn ◽

Niki Heuvelmans ◽

...

Keyword(s):

Duchenne Muscular Dystrophy ◽

Muscular Dystrophy ◽

Antisense Oligonucleotides ◽

Exon Skipping

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Human iPSC-derived RPE and retinal organoids reveal impaired alternative splicing of genes involved in pre-mRNA splicing in PRPF31 autosomal dominant retinitis pigmentosa

10.1101/232397 ◽

2017 ◽

Author(s):

Adriana Buskin ◽

Lili Zhu ◽

Valeria Chichagova ◽

Basudha Basu ◽

Sina Mozaffari-Jovin ◽

...

Keyword(s):

Alternative Splicing ◽

Retinitis Pigmentosa ◽

Gene Editing ◽

Autosomal Dominant ◽

Mrna Processing ◽

Mrna Splicing ◽

Patient Specific ◽

Rpe Cells ◽

Autosomal Dominant Retinitis Pigmentosa

SummaryMutations in pre-mRNA processing factors (PRPFs) cause 40% of autosomal dominant retinitis pigmentosa (RP), but it is unclear why mutations in ubiquitously expressed PRPFs cause retinal disease. To understand the molecular basis of this phenotype, we have generated RP type 11 (PRPF31-mutated) patient-specific retinal organoids and retinal pigment epithelium (RPE) from induced pluripotent stem cells (iPSC). Impaired alternative splicing of genes encoding pre-mRNA splicing proteins occurred in patient-specific retinal cells and Prpf31+/− mouse retinae, but not fibroblasts and iPSCs, providing mechanistic insights into retinal-specific phenotypes of PRPFs. RPE was the most affected, characterised by loss of apical-basal polarity, reduced trans-epithelial resistance, phagocytic capacity, microvilli, and cilia length and incidence. Disrupted cilia morphology was observed in patient-derived-photoreceptors that displayed progressive features associated with degeneration and cell stress. In situ gene-editing of a pathogenic mutation rescued key structural and functional phenotypes in RPE and photoreceptors, providing proof-of-concept for future therapeutic strategies.eTOCPRPF31 is a ubiquitously expressed pre-mRNA processing factor that when mutated causes autosomal dominant RP. Using a patient-specific iPSC approach, Buskin and Zhu et al. show that retinal-specific defects result from altered splicing of genes involved in the splicing process itself, leading to impaired splicing, loss of RPE polarity and diminished phagocytic ability as well as reduced cilia incidence and length in both photoreceptors and RPE.HighlightsSuccessful generation of iPSC-derived RPE and photoreceptors from four RP type 11 patientsRPE cells express the mutant PRPF31 protein and show the lowest expression of wildtype proteinPRPF31 mutations result in altered splicing of genes involved in pre-mRNA splicing in RPE and retinal organoidsPrpf31 haploinsufficiency results in altered splicing of genes involved in pre-mRNA splicing in mouse retinaRPE cells display loss of polarity, reduced barrier function and phagocytosisPhotoreceptors display shorter and fewer cilia and degenerative featuresRPE cells display most abnormalities suggesting they might be the primary site of pathogenesisIn situ gene editing corrects the mutation and rescues key phenotypes

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