ISLR regulates skeletal muscle atrophy via IGF1-PI3K/Akt-Foxo signaling pathway

Immunoglobulin superfamily containing leucine-rich repeat (Islr) contains an Ig-like domain, an LRR motif, and a transmembrane domain and is highly expressed in various chicken tissues. Although Islr has known roles in muscle regeneration, its role in the regulation of muscle atrophy has not been studied. In this study, we constructed Islr-silenced or Islr-overexpressed myoblasts to investigate its role during the differentiation of myoblasts into myotubes. The results showed that Islr was highly expressed in chicken skeletal muscle tissue and regulated myoblast differentiation, but not proliferation. Islr regulated the expression of atrophy-related genes including atrogin-1 and MuRF-1, and could rescue dexamethasone-induced atrophy in myoblasts and myotubes. Western blot analysis indicated that Islr participates in myoblast atrophy through IGF/PI3K/AKT-FOXO signaling. Meanwhile, the expression of caspase-8 and caspase-9 increased in Islr-silenced groups, indicating its role in cell viability. Taken together, these data suggested that Islr plays an important role in myoblasts differentiation, and which can alleviate skeletal muscle atrophy and prevents muscle cell apoptosis via IGF/PI3K/AKT-FOXO signaling pathway.