Correction: Challenges associated with homologous directed repair using CRISPR-Cas9 and TALEN to edit the DMD genetic mutation in canine Duchenne muscular dystrophy.
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ABSTRACT:
SUBMITTER: Mata Lopez S
PROVIDER: S-EPMC7580940 | biostudies-literature | 2020
REPOSITORIES: biostudies-literature
Publications
Correction: Challenges associated with homologous directed repair using CRISPR-Cas9 and TALEN to edit the DMD genetic mutation in canine Duchenne muscular dystrophy.
Mata López Sara S Balog-Alvarez Cynthia C Vitha Stanislav S Bettis Amanda K AK Canessa Emily H EH Kornegay Joe N JN Nghiem Peter P PP
PloS one 20201022 10
[This corrects the article DOI: 10.1371/journal.pone.0228072.]. ...[more]
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Project description:BackgroundBoys with Duchenne muscular dystrophy (DMD) have DMD gene mutations, with associated loss of the dystrophin protein and progressive muscle degeneration and weakness. Corticosteroids and palliative support are currently the best treatment options. The long-term benefits of recently approved compounds such as eteplirsen and ataluren remain to be seen. Dogs with naturally occurring dystrophinopathies show progressive disease akin to that of DMD. Accordingly, canine DMD models are useful for studies of pathogenesis and preclinical therapy development. A dystrophin-deficient, male border collie dog was evaluated at the age of 5 months for progressive muscle weakness and dysphagia.Case presentationDramatically increased serum creatine kinase levels (41,520 U/L; normal range 59-895 U/L) were seen on a biochemistry panel. Histopathologic changes characteristic of dystrophinopathy were seen. Dystrophin was absent in the skeletal muscle on immunofluorescence microscopy and western blot. Whole genome sequencing, polymerase chain reaction, and Sanger sequencing revealed a frameshift, single nucleotide deletion in canine DMD exon 20, position 27,626,466 (c.2841delT mRNA), resulting in a stop codon six nucleotides downstream. Semen was archived for future line perpetuation.ConclusionsThis spontaneous canine dystrophinopathy occurred due to a novel mutation in the minor DMD mutation hotspot (between exons 2 through 20). Perpetuating this line could allow for preclinical testing of genetic therapies targeted to this area of the DMD gene.
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Project description:Duchenne muscular dystrophy (DMD) is a severe muscle-degenerative disease caused by a mutation in the dystrophin gene. Genetic correction of patient-derived induced pluripotent stem cells (iPSCs) by TALENs or CRISPR-Cas9 holds promise for DMD gene therapy; however, the safety of such nuclease treatment must be determined. Using a unique k-mer database, we systematically identified a unique target region that reduces off-target sites. To restore the dystrophin protein, we performed three correction methods (exon skipping, frameshifting, and exon knockin) in DMD-patient-derived iPSCs, and found that exon knockin was the most effective approach. We further investigated the genomic integrity by karyotyping, copy number variation array, and exome sequencing to identify clones with a minimal mutation load. Finally, we differentiated the corrected iPSCs toward skeletal muscle cells and successfully detected the expression of full-length dystrophin protein. These results provide an important framework for developing iPSC-based gene therapy for genetic disorders using programmable nucleases.
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Project description:Dystrophin deficiency results in lethal Duchenne muscular dystrophy (DMD). Substituting missing dystrophin with abbreviated microdystrophin has dramatically alleviated disease in mouse DMD models. Unfortunately, translation of microdystrophin therapy has been unsuccessful in dystrophic dogs, the only large mammalian model. Approximately 70% of the dystrophin-coding sequence is removed in microdystrophin. Intriguingly, loss of ?50% dystrophin frequently results in severe disease in patients. To test whether the small gene size constitutes a fundamental design error for large mammalian muscle, we performed a comprehensive study using 22 dogs (8 normal and 14 dystrophic). We delivered the ?R2-15/?R18-19/?R20-23/?C microdystrophin gene to eight extensor carpi ulnaris (ECU) muscles in six dystrophic dogs using Y713F tyrosine mutant adeno-associated virus (AAV)-9 (2.6 × 10(13) viral genome (vg) particles/muscle). Robust expression was observed 2 months later despite T-cell infiltration. Major components of the dystrophin-associated glycoprotein complex (DGC) were restored by microdystrophin. Treated muscle showed less inflammation, fibrosis, and calcification. Importantly, therapy significantly preserved muscle force under the stress of repeated cycles of eccentric contraction. Our results have established the proof-of-concept for microdystrophin therapy in dystrophic muscles of large mammals and set the stage for clinical trial in human patients.
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Project description:Duchenne and Becker muscular dystrophy (DMD and BMD) are caused, in the majority of cases, by deletions in the dystrophin gene (DMD). The disease is an X-linked neuromuscular diseases typically caused by disrupting (DMD) or non-disrupting (BMD) the reading frame in the dystrophin (DMD) gene. In the present study, amplifications of the genomic DNAs of unrelated 15 Saudi DMD males were carried out using multiplex polymerase chain reaction (PCR) for nine-hotspot regions of exons 4, 8, 12, 17, 19, 44, 45, 48 and 51. We detected six Saudi patients having deletions in a frequency of 40%. The frequency of deletions in exon 51 (20%) was the most common deletion frequently associated with our Saudi sample males. Exons 19, 45, and 48 were present in a frequency of 6.7% each. All deletions were recognized as an individual exonic deletions, while no gross deletion where detected. Finally, the molecular deletions in the Saudi males was expected to be characterized by a moderate frequency among different populations due to the geographical KSA region, which it is in the crossroad of intense migrations and admixture of people coming from continental Asia, Africa, and even Europe. In conclusion, attempts to include an extra DNA samples might reflect a valid vision of the deletions within the high frequency deletion regions (HFDR's) in the DMD gene mutations in KSA.
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Project description:Discovery of the CRISPR-Cas (clustered regularly interspaced short palindromic repeat, CRISPR-associated) system a decade ago has opened new possibilities in the field of precision medicine. CRISPR-Cas was initially identified in bacteria and archaea to play a protective role against foreign genetic elements during viral infections. The application of this technique for the correction of different mutations found in the Duchenne muscular dystrophy (DMD) gene led to the development of several potential therapeutic approaches for DMD patients. The mutations responsible for Duchenne muscular dystrophy mainly include exon deletions (70% of patients) and point mutations (about 30% of patients). The CRISPR-Cas 9 technology is becoming increasingly precise and is acquiring diverse functions through novel innovations such as base editing and prime editing. However, questions remain about its translation to the clinic. Current research addressing off-target editing, efficient muscle-specific delivery, immune response to nucleases, and vector challenges may eventually lead to the clinical use of the CRISPR-Cas9 technology. In this review, we present recent CRISPR-Cas9 strategies to restore dystrophin expression in vitro and in animal models of DMD.
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