Transforming growth factor- -regulated miR-24 promotes skeletal muscle differentiation

Abstract

MicroRNAs (miRNAs) have recently been proposed as a versatile class of molecules involved in regulation of a variety of biological processes. However, the role of miRNAs in TGF-β-regulated biological processes is poorly addressed. In this study, we found that miR-24 was upregulated during myoblast differentiation and could be inhibited by TGF-β1. Using both a reporter assay and Northern blot analysis, we showed that TGF-β1 repressed miR-24 transcription which was dependent on the presence of Smad3 and a Smads binding site in the promoter region of miR-24. TGF-β1 was unable to inhibit miR-24 expression in Smad3-deficient myoblasts, which exhibited accelerated myogenesis. Knockdown of miR-24 led to reduced expression of myogenic differentiation markers in C2C12 cells, while ectopic expression of miR-24 enhanced differentiation, and partially rescued inhibited myogenesis by TGF-β1. This is the first study demonstrating a critical role for miRNAs in modulating TGF-β-dependent inhibition of myogenesis, and provides a novel mechanism of the genetic regulation of TGF-β signaling during skeletal muscle differentiation.

Comprehensive fine mapping of chr12q12-14 and follow-up replication identify activin receptor 1B (ACVR1B) as a muscle strength gene

“…Wang et al 43 showed that miR-24 could decrease human ACVR1B expression at mRNA and protein levels. Published evidence 46 showed that this miR-24 is involved in the inhibition of skeletal muscle differentiation by TGFb. Even though miR-24 is not a muscle-specific miRNA, they suggested that miR-24 might function during differentiation and homeostatic maintenance of cardiac and skeletal muscle tissue.…”

Competition between human cells by entosis

“…For immunostaining [45], cells were fixed with 4% PFA or 10% TCA, permeabilized with 0.2% Triton X-100/PBS for 5 min followed by blocking with 5% BSA for 1 h, and were incubated with primary antibodies in a humidified box overnight, followed by three 10-min washes with PBS. Secondary antibodies were applied for 1 h followed by three 10-min washes with PBS, and cells were counter-stained with DAPI and mounted with Prolong Gold antifade reagent (Invitrogen).…”

Human respiratory syncytial virus non-structural protein NS1 modifies miR-24 expression via transforming growth factor-β

“…TGF-b expression during RSV infection has been shown to be important for cell cycle inhibition in the G 0 /G 1 phase (Gibbs et al, 2009;McCann & Imani, 2007;Wu et al, 2011) and miR-24 has been shown to be suppressed by TGF-b (Sun et al, 2008), as well as regulate TGF-b precursor processing (Luna et al, 2011). As preliminary data showed a role for NS1 in regulating miR-24 expression, the impact of NS1 overexpression on TGF-b expression was determined.…”

“…TGF-b treatment has been shown to increase RSV replication in A549 as well as primary NHBE cells (Gibbs et al, 2009). TGF-b has also been shown to inhibit miR-24 expression in other cell types (Cao et al, 2012;Sun et al, 2008) …”