Lysine methyltransferase 2D regulates muscle fiber size and muscle cell differentiation

• DOI: 10.1096/fj.202100823r
• Publication Date: 2021-10-08T22:19:36Z
• Authors: Alec Wright; Arielle Hall; Tara Daly; Tatiana Fontelonga; Sarah Potter; Caitlin Schafer; Andrew Lindsley; Christina Hung; Olaf Bodamer; Emanuela Gussoni
• Keywords: Male; 0301 basic medicine; Muscle Cells; Adolescent; Muscle Fibers, Skeletal; Infant; Cell Differentiation; Mice, Transgenic; Histone-Lysine N-Methyltransferase; Hematologic Diseases; DNA-Binding Proteins; Disease Models, Animal; Mice; 03 medical and health sciences; Child, Preschool; Face; Mutation; Animals; Humans; Abnormalities, Multiple; Female; Child; Research Articles

Kabuki syndrome (KS) is a rare genetic disorder caused primarily by mutations in the histone modifier genes KMT2D and KDM6A. The genes have broad temporal and spatial expression in many organs, resulting in complex phenotypes observed in KS patients. Hypotonia is one of the clinical presentations associated with KS, yet detailed examination of skeletal muscle samples from KS patients has not been reported. We studied the consequences of loss of KMT2D function in both mouse and human muscles. In mice, heterozygous loss of Kmt2d resulted in reduced neuromuscular junction (NMJ) perimeter, decreased muscle cell differentiation in vitro and impaired myofiber regeneration in vivo. Muscle samples from KS patients of different ages showed presence of increased fibrotic tissue interspersed between myofiber fascicles, which was not seen in mouse muscles. Importantly, when Kmt2d-deficient muscle stem cells were transplanted in vivo in a physiologic non-Kabuki environment, their differentiation potential is restored to levels undistinguishable from control cells. Thus, the epigenetic changes due to loss of function of KMT2D appear reversible through a change in milieu, opening a potential therapeutic avenue.