Abstract
MicroRNAs are evolutionarily conserved, small non-coding RNAs that play critical post-transcriptional regulatory roles in skeletal muscle development. We previously found that miR-9-5p is abundantly expressed in chicken skeletal muscle. Here, we demonstrate a new role for miR-9-5p as a myogenic microRNA that regulates skeletal muscle development. The overexpression of miR-9-5p significantly inhibited the proliferation and differentiation of skeletal muscle satellite cells (SMSCs), whereas miR-9-5p inhibition had the opposite effect. We show that insulin-like growth factor 2 mRNA-binding protein 3 (IGF2BP3) is a target gene of miR-9-5p, using dual-luciferase assays, RT-qPCR, and Western Blotting, and that it promotes proliferation and differentiation of SMSCs. In addition, we found that IGF2BP3 regulates IGF-2 expression, using overexpression and knockdown studies. We show that Akt is activated by IGF2BP3 and is essential for IGF2BP3-induced cell development. Together, our results indicate that miR-9-5p could regulate the proliferation and differentiation of myoblasts by targeting IGF2BP3 through IGF-2 and that this activity results in the activation of the PI3K/Akt signaling pathway in skeletal muscle cells.
Highlights
Skeletal muscle is the most abundant tissue in our body, accounting for approximately 40%–60% of body mass in adult humans and animals [1]
Through analysis of our previous miRNA-Seq and RNA-Seq data (NCBI accession number PRJNA516545), we identified insulin-like growth factor 2 mRNA-binding protein 3 (IGF2BP3) as the target gene of miR-9-5p
When skeletal muscle satellite cells (SMSCs) were transfected with the miR-9-5p mimic, the expression of miR-9-5p increased by over 180 times (Figure 1B), whereas a 50-fold decrease in expression was found in SMSCs treated with the inhibitor (Figure 1C)
Summary
Skeletal muscle is the most abundant tissue in our body, accounting for approximately 40%–60% of body mass in adult humans and animals [1]. The loss of function of skeletal muscle, especially through distorted muscle differentiation, causes various diseases, including cancer and diabetes [2]. Skeletal muscle is the most economically valuable tissue in meat-producing animals, and its quantity and quality determine the efficiency of production [3]. Skeletal muscle is composed of post-mitotic multinucleated myofibroblasts [4]. Its development is a tightly regulated, multi-step process in which mesodermal precursor myoblasts differentiate into myoblasts and fuse to form multinucleated myofibers [5]. Myogenesis is orchestrated through various myogenic transcription factors (including DNA, peptides and noncoding RNAs) and various signaling pathways [6]
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