Recently, a novel class of muscular dystrophy has been discovered in a family due to autosomal recessive missense mutation in POGLUT1. Mutation of this enzyme leads to decreased O-glucosyltransferase activity and impaired Notch signaling, the pathways important for skeletal muscle stem cell (satellite cells) quiescence and activation. We hypothesize that reduced POGLUT1 activity and impaired Notch signaling is causative of this limb girdle muscular dystrophy through dysfunction of muscle stem cells and myogenic progenitors.
To test this, we have used iPSCs for disease modeling and rescue experiments. Using a CRISPR based gene targeting method, we aimed to correct the point mutation and restore POGLUT1 function, thus restoring Notch signaling activity. Following correction, iPSC-derived gene corrected myogenic cells were differentiated and compared to healthy control and patient cell line (isogenic control). Compared to patient cells, gene-corrected cells demonstrated superior ability to proliferate and improved myogenic potential as compared to patient uncorrected cells. In addition, Notch signaling pathway activity was improved in the corrected cells as a result of the POGULT1 gene correction. These results support our hypothesis that POGULT1 modulates Notch signaling in myogenic cells and its involvement may be responsible for the development of this type of LGMD
