IgLON5 Regulates the Adhesion and Differentiation of Myoblasts.

IgLON5 is a cell adhesion protein belonging to the immunoglobulin superfamily and has important cellular functions. The objective of this study was to determine the role played by IgLON5 during myogenesis. We found IgLON5 expression progressively increased in C2C12 myoblasts during transition from the adhesion to differentiation stage. IgLON5 knockdown (IgLON5kd) cells exhibited reduced cell adhesion, myotube formation, and maturation and reduced expressions of different types of genes, including those coding for extracellular matrix (ECM) components (COL1a1, FMOD, DPT, THBS1), cell membrane proteins (ITM2a, CDH15), and cytoskeletal protein (WASP). Furthermore, decreased IgLON5 expression in FMODkd, DPTkd, COL1a1kd, and ITM2akd cells suggested that IgLON5 and these genes mutually control gene expression during myogenesis. IgLON5 immunoneutralization resulted in significant reduction in the protein level of myogenic markers (MYOD, MYOG, MYL2). IgLON5 expression was higher in the CTX-treated gastrocnemius mice muscles (day 7), which confirmed increase expression of IgLON5 during muscle. Collectively, these results suggest IgLON5 plays an important role in myogenesis, muscle regeneration, and that proteins in ECM and myoblast membranes form an interactive network that establishes an essential microenvironment that ensures muscle stem cell survival.