miR-193b-3p Promotes Proliferation of Goat Myoblast Through Directly Targeting IGF2BP1 and Activating Its Transcription

Abstract

BackgroundAs a well-known cancer-related miRNA, miR-193b-3p is enriched in skeletal muscle but dysregulated in muscle disease. However, mechanism underpinning has not been addressed so far. MethodsHere, we probed the impact of miR-193b-3p on myogenesis by mainly using goat tissues and skeletal muscle satellite cells (MuSCs), with combined methods including RNA-seq to profile the transcriptome affected by miR-193b-3p, cell-counting kit-8 (CCK-8) and 5-ethynyl-2'-deoxyuridine (EdU) for cell proliferation assay, and RNA-RNA dual-labeled fluorescence in situ hybridization (FISH) for RNA colocalization. ResultsmiR-193b-3p is highly enriched in goat skeletal muscles, and ectopic miR-193b-3p promotes MuSCs proliferation and differentiation. Moreover, insulin-like growth factor-2 mRNA-binding protein 1 (IGF2BP1) is the most activated insulin signaling genes when overexpression miR-193b-3p and the miRNA recognition element (MRE) within IGF1BP1 3ʹ untranslated region (UTR) is indispensable for its activation caused by miR-193b-3p. Consistently, expression patterns and function of IGF2BP1 were similar to those of miR-193b-3p in tissues and MuSCs. While the overexpression of miR-193b-3p failed to induce pax7 expression and myoblast proliferation when IGF2BP1 knockdown. Furthermore, miR-193b-3p destabilized IGF2BP1 mRNA but unexpectedly promoted levels of IGF2BP1 heteronuclear RNA (hnRNA) dramatically. Moreover, miR-193b-3p could enhance fly luciferase activity when inserted upstream of its promoter, and induce neighboring genes of itself. However, miR-193b-3p inversely regulated IGF2BP1 and myoblast proliferation in mouse C2C12 myoblast. These data unveil that goat miR-193b-3p promotes myoblast proliferation via activating IGF2BP1 by binding on its 3ʹ UTR.ConclusionsOur novel findings highlight the positive regulation between miRNA and its target genes in muscle development, which further extends the repertoire of miRNA functions.