A Novel Class of FKBP12 Ligands Rescues Premature Aging Phenotypes Associated with Myotonic Dystrophy Type 1

<b>Background:</b> Myotonic dystrophy type 1 (DM1) is an autosomal dominant disorder clinically characterized by progressive muscular weakness and multisystem degeneration, which correlates with the size of CTG expansion and MBLN decrease. These changes induce a calcium and redox homeostasis imbalance in several models that recapitulate the features of premature tissue aging. In this study, we characterized the impact of a new family of FKBP12 ligands (generically named MPs or MP compounds) designed to stabilize FKBP12 binding to the ryanodine receptors and normalize calcium dysregulation under oxidative stress. <b>Methods:</b> Human primary fibroblasts from DM1 patients and control donors, treated with MP compounds or not, were used for functional studies of cell viability, proliferation, and metabolism. The gene expression profile in treated cells was determined using RNA sequencing. The impact of MP compounds in vivo was evaluated in a <i>Drosophila</i> model of the disease using locomotor activity and longevity studies. <b>Results:</b> The treatment with different MP compounds reversed oxidative stress and impaired cell viability and proliferation, mitochondrial activity, and metabolic defects in DM1-derived primary fibroblasts. RNA sequencing analysis confirmed the restoration of molecular pathways related to calcium and redox homeostasis and additional pathways, including the cell cycle and metabolism. This analysis also revealed the rescue of alternative splicing events in DM1 fibroblasts treated with MP compounds. Importantly, treatment with MP compounds significantly extended the lifespan and improved the locomotor activity of a <i>Drosophila</i> model of the DM1 disease, and restored molecular defects characteristic of the disease in vivo. <b>Conclusions:</b> Our results revealed that MP compounds rescue multiple premature aging phenotypes described in DM1 models and decipher the benefits of this new family of compounds in the pre-clinical setting of DM1.