Biology subjects

Coenen-Stass, A. M. L.

Publications and source records attributed to Coenen-Stass, A. M. L..

4 recordsLinked to original sources

bioRxiv2025

Timing matters: exon skipping therapy is most effective when initiated early in a mouse model of Duchenne muscular dystrophy

Exon skipping is a leading therapeutic approach for Duchenne muscular dystrophy (DMD), a progressive muscle wasting disorder caused by pathogenic variants in the DMD gene that typically disrupt the translation reading frame. This approach aims to modulate DMD pre-mRNA splicing to re-frame the transcript and generate an internally deleted but partially functional quasi-dystrophin protein. Four exon skipping drugs have received FDA accelerated approval, although their clinical efficacy is very limited. To investigate how treatment timing influences exon skipping outcomes, dystrophin-deficient mdx mice were injected with peptide-phosphorodiamidate morpholino oligonucleotide (PPMO) exon skipping conjugates beginning at either the adult (12-week) or aged (75-week) stages, and tibialis anterior muscles harvested for biochemical and transcriptomic analyses. Mean Dmd exon 23 skipping was 79% in adults and 44% in aged PPMO-treated mdx mice, whereas dystrophin protein restoration was 35% and 8%, respectively. Histopathological improvements were only evident in the adult-treated mice. PPMO-treatment in adult mdx mice induced a broad transcriptomic shift towards a wild-type signature, whereas treatment in aged mice resulted in negligible gene expression changes, indicating that late intervention is ineffective at reversing disease-associated pathologies despite low-level dystrophin restoration. Dystrophin transcript imbalance was corrected only in adult-treated mdx mice. Increased expression of the dystrophin-repressing microRNA miR-31-5p, which was more strongly upregulated in aged mdx muscle, provides a potential mechanistic explanation. In conclusion, PPMO-mediated exon skipping is substantially more effective when initiated in adult rather than aged dystrophic muscle, supporting early therapeutic intervention in DMD-affected individuals.

neuroscience↗

bioRxiv2022

PPMO-mediated exon skipping induces uniform sarcolemmal dystrophin rescue with dose-dependent restoration of circulating microRNA biomarkers and muscle biophysical properties

Duchenne muscular dystrophy (DMD) is a paediatric muscle-wasting disorder caused by genetic loss of the gene encoding the dystrophin protein. Therapies that restore dystrophin expression are presumed to correct the disease, with antisense-mediated exon skipping being the leading approach. In this study, we aimed to determine whether exon skipping using a peptide-phosphorodiamidate morpholino oligonucleotide (PPMO) conjugate results in dose-dependent restoration of uniform dystrophin localization, together with correction of putative DMD serum and muscle biomarkers. To this end, dystrophin-deficient mdx mice were treated with a PPMO (Pip9b2-PMO) designed to induce Dmd exon 23 skipping and dystrophin rescue at single, ascending intravenous doses (3, 6, or 12 mg/kg) and sacrificed two weeks later. Dose-dependent exon skipping and dystrophin protein restoration were observed. Importantly, dystrophin expression was uniformly distributed at the sarcolemma of corrected myofibers at all doses. The abundance of serum microRNA biomarkers (i.e. miR-1a-3p, miR-133a-3p, miR-206-3p, miR-483-3p) and creatinine kinase were restored towards wild-type levels after treatment in a dose-dependent manner. All biomarkers were strongly anti-correlated with both exon skipping level and dystrophin expression. Dystrophin rescue was also strongly positively correlated with muscle stiffness (i.e. Youngs modulus) as determined by atomic force microscopy (AFM) nanoindentation assay. These data demonstrate that PPMO-mediated exon skipping generates myofibers with uniform dystrophin expression, and that both serum miRNA biomarkers and muscle AFM have potential utility as pharmacodynamic biomarkers of dystrophin restoration therapy in the context of DMD.

molecular biology↗

bioRxiv2022

Non-uniform dystrophin re-expression after CRISPR-mediated exon excision in the dystrophin/utrophin double-knockout mouse model of DMD

Duchenne muscular dystrophy (DMD) is the most prevalent inherited myopathy affecting children, caused by genetic loss of the gene encoding the dystrophin protein. There are currently four FDA-approved drugs for DMD that aim to restore expression of dystrophin by exon skipping using splice switching oligonucleotides. While these therapies require lifelong repeat administration, recent advancements in gene editing technologies have raised the possibility of achieving permanent exon skipping, and thereby curing the disease with a single treatment. Here we have investigated the use of the Staphylococcus aureus CRISPR/Cas9 system and a double-cut strategy, delivered using a pair of AAV9 vectors, for dystrophin restoration in the severely-affected dystrophin/utrophin double knock-out (dKO) mouse. Single guide RNAs were designed to induce double-strand DNA breaks on either side of Dmd exon 23, such that the intervening exon 23 sequence is excised when the flanking intronic regions are joined via the non-homologous end joining repair pathway. Exon 23 deletion was confirmed at the DNA level by PCR and Sanger sequencing, and at the RNA level by RT-qPCR. Restoration of dystrophin protein expression was demonstrated by western blot and immunofluorescence staining in mice treated via either intraperitoneal or intravenous routes of delivery. Dystrophin restoration was most effective in the diaphragm, where a maximum of 5.7% of wild-type dystrophin expression was observed. CRISPR treatment was insufficient to extend lifespan in the dKO mouse, and dystrophin was expressed in a within-fiber patchy manner in skeletal muscle tissues. Further analysis revealed a plethora of non-productive DNA repair events, including AAV genome integration at the CRISPR cut sites. This study highlights potential challenges for the successful development of CRISPR therapies in the context of DMD.

molecular biology↗

bioRxiv2019

Circulating miR-181 is a prognostic biomarker for amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a relentless neurodegenerative syndrome of the human motor neuron system, for which no effective treatment exists. Variability in the rate of disease progression limits the efficacy of ALS clinical trials, suggesting that developing of better biomarkers for prognosis will facilitate therapeutic progress. Here, we applied unbiased next-generation sequencing to investigate the potential of plasma cell-free microRNAs as biomarkers of ALS prognosis, in 252 patients with detailed clinical-phenotyping. First, we identified miRNAs, whose plasma levels remain stable over the course of disease in a longitudinal cohort of 22 patients. Next, we demonstrated that high levels of miR-181, a miRNA enriched in neurons of the brain and spinal cord, predicts a >2 fold risk of death in discovery cohort (126 patients) and an independent replication cohort (additional 122 patients). miR-181 performance is comparable with the established neurofilament light chain (NfL) biomarker and when combined together, miR-181+NfL establish a novel RNA-protein biomarker pair with superior prediction capacity of ALS prognosis. Therefore, plasma miR-181 predicts ALS disease course, and a novel miRNA-protein biomarker approach, based on miR-181+NfL, boosts precision of patient stratification and may greatly enhance the power of clinical trials. One Sentence Summaryplasma miR-181 levels indicate high mortality risk in ALS patients.

neuroscience↗