Therapeutic targeting of a pathological microRNA in DMD


Translational Research

Poster Number: 157


Anders Naar, PhD, University of California, Berkeley and Innovative Genomics Institute, Lei Xu, PhD, University of California, Berkeley, Sneha Villivalam, PhD, University of California, Berkeley, Alexandre Wagschal, PhD, Exonics, Sona Kang, PhD, University of California, Berkeley, Louis Kunkel, PhD, Boston Children's Hospital

Duchenne muscular dystrophy (DMD), an early lethal X-linked muscle wasting disease caused by dystrophin loss, has few effective treatment options. While exon-skipping and CRISPR correction strategies aimed at restoring partially functional dystrophin may help a subset of patients, the majority still has no efficacious treatment alternatives. Novel approaches that target secondary deleterious effects downstream of dystrophin deficiency, such as abnormal mitochondrial metabolism, have recently shown some success. Indeed, increased expression or pharmacological activation of proteins involved in promoting mitochondrial biogenesis/function, including PPARs, PGC1a, AMPK and SIRT1, partially ameliorate DMD pathologies in animal models. We have recently identified a microRNA, miR-128-1, as a crucial negative regulator of PPARs, PGC1a, AMPK, SIRT1 and other genes involved in mitochondrial biogenesis/function in skeletal muscle (Wang et al. Cell 2020). Interestingly, the miR-128-1 genomic locus is also strongly linked to weak grip strength and poor lung muscle function in the UK Biobank (>300,000 individuals). Moreover, we and others have found that skeletal muscle and circulating plasma levels of miR-128-1 is elevated in zebrafish, mouse, and dog DMD models as well as in DMD patients. We thus hypothesized that miR-128-1 may act as a pathological modifier downstream of dystrophin loss. Excitingly, our studies in the mdx-5cv mouse model have shown that once-weekly subcutaneous administration of a locked nucleic acid (LNA) antisense oligonucleotide (ASO) targeting miR-128-1 at 10 mg/kg dramatically rescued all pathological manifestations of dystrophin loss after only a few weeks of treatment. We observe a ~90% decrease in circulating creatine kinase, near wildtype level of rescue of grip strength and treadmill endurance/speed, nearly complete absence of muscle necrosis, ~80% decrease in muscle fibrosis, complete reversal of muscle type switching, markedly increased muscle fiber diameter, rescue of mitochondrial defects (elevated ROS and mitochondrial numbers) to near wildtype levels, potently decreased inflammation, and de-repression of direct miR-128-1 targets such as PPARs, PGC1a, AMPK, SIRT1, INSR, IRS1 etc. Moreover, our next-gen LNA ASO can be dosed once-monthly with 100% suppression of miR-128-1 in muscle and heart. Anti-miR-128-1 may thus represent an attractive therapeutic for DMD.