Inhibition of miR-29 by TGF-beta-Smad3 Signaling through Dual Mechanisms Promotes Transdifferentiation of Mouse Myoblasts into Myofibroblasts

Abstract

MicroRNAs (miRNAs) are non-coding RNAs that regulate gene expression in post-transcriptional fashion, and emerging studies support their importance in regulating many biological processes, including myogenic differentiation and muscle development. miR-29 is a promoting factor during myogenesis but its full spectrum of impact on muscle cells has yet to be explored. Here we describe an analysis of miR-29 affected transcriptome in C2C12 muscle cells using a high throughput RNA-sequencing platform. The results reveal that miR-29 not only functions to promote myogenic differentiation but also suppresses the transdifferentiation of myoblasts into myofibroblasts. miR-29 inhibits the fibrogenic differentiation through down-regulating both extracellular matrix genes and cell adhesion genes. We further demonstrate that miR-29 is under negative regulation by TGF-beta (TGF-β)–Smad3 signaling via dual mechanisms of both inhibiting MyoD binding and enhancing Yin Yang 1 (YY1)-recruited Polycomb association. Together, these results identify miR-29 as a pleiotropic molecule in both myogenic and fibrogenic differentiation of muscle cells.

LncRNA Dum interacts with Dnmts to regulate Dppa2 expression during myogenic differentiation and muscle regeneration

“…To test this notion, we depleted Dum in mouse limb muscles during injury-induced regeneration using intramuscular injection of siRNA oligos as described before [17][18][19]. As illustrated in Figure 3A, the injection of siDum or negative control oligos was performed three times on days 1/4, 2 and 4 post CTX injection and muscles were harvested at the designated times for analyses.…”

The role of miR-29 family members in malignant hematopoiesis

“…Promoter region of mouse miR-29b-2/c contains four E-box binding sites for MyoD with close proximity to SBE. Independently of these sites the CCAT box binding YY1 is located 22 . MyoD is a transcriptional factor influencing differentiation of skeletal muscle cells 23 .…”

“…If Smad3 is not activated by TGF-β, MyoD would bind to the promoter E-box and transcription of miR-29 follows. Therefore TGF-β-Smad3 signaling pathway modulates the miR-29 expression by two mechanisms 22 . Post-transcriptional manner of miR-29 regulation was observed in HeLa cells.…”

“…Relationship between miR-29 expression and extracellular matrix proteins was investigated for example for Collagens and Matrix metalloproteinase 2 (MMP2) (ref. 22,[32][33][34][35][36] ). In myogenic differentiation and skeletal myogenesis target genes influenced by miR-29 family members expression were also found, for example TGF-β, HDAC4 or YY1 (ref.…”

MicroRNAs Involved in the Regulation of Postischemic Cardiac Fibrosis

“…Additionally, the number of myofibroblasts, which are partially transformed from fibroblasts and are the real effectors of fibrosis, increased significantly after tail vein injection of anti-miR-29b. Zhou et al 30 provided further evidence for a role of miR-29 in the development of fibrosis after myocardial infarction. Their study showed downregulation of miR-29 in response to overexpression of TGF-β via activation of Smad2 and Smad3, transcription factors that transduce extracellular TGF-β from cell membrane to cytoplasm.…”