miR-146a-5p acts as a negative regulator of TGF-β signaling in skeletal muscle after acute contusion

Abstract

Growing evidence suggests the importance of microRNAs (miRNAs) in stress signaling pathways. Transforming growth factor-β (TGF-β) is a potent cytokine that promotes the development of skeletal muscle fibrosis after acute contusion. However, how miRNAs are involved in TGF-β signaling and confer the robustness of TGF-β-induced fibrotic response remains to be fully elucidated. Here, we demonstrated that miR-146a-5p (miR-146) levels were reduced in a fibrotic mouse model after acute muscle contusion. It was also found that TGF-β treatment decreased the expression of miR-146 in vitro in a dose- and time-dependent manner. In addition, overexpression of Smad3 and Samd4, two key players in TGF-β signaling, suppressed the expression of miR-146 in muscle cells. Overexpression of miR-146 inhibited the expressions of fibrosis markers both in vitro and in vivo. Moreover, increase in the expression of miR-146 in muscle cells was able to attenuate the effect of TGF-β on the expressions of fibrosis markers. Mechanistic analysis revealed that Smad4 is a direct target of miR-146 in muscle cells. Furthermore, the anti-fibrotic effect of miR-146 could be blocked by overexpression of Smad4 in vivo. These results suggest that Smad4 is down-regulated by miR-146 in skeletal muscle. Taken together, our results indicate that the anti-fibrotic miR-146 is a component of TGF-β signaling. It is down-regulated by Smad protein, and can inhibit the expression of Smad4. Our study suggests that miR-146 might have a therapeutic potential to reduce skeletal muscle fibrosis after injury.

Role of microRNA-146a in regulation of fibrosis in orbital fibroblasts from patients with Graves’ orbitopathy

“…The authors suggested that miR-146a may be a therapeutic option for end-stage renal disease. Sun et al 34 have recently reported that miR-146a acts as a negative regulator of TGF-β signalling in skeletal muscle after acute contusion. In the present study, we confirmed that Smad4 and TRAF6 might also be target genes of miR-146a in orbital fibroblasts.…”

miR‐122‐5p negatively regulates the transforming growth factor‐β/Smad signaling pathway in skeletal muscle myogenesis

“…Total RNA was reversely transcribed by using a PrimeScript RT reagent kit (Takara, Dalian, China). For small RNAs, stem loop RT‐qPCR (TaqMan; Thermo Scientific, Wilmington, North Carolina) was used to detect difference in the levels of miRs as previously described . Each sample was run in triplicate.…”

“…Regeneration and fibrosis are the two major challenges for injured skeletal muscle repair. For that reason, studies on post‐injury skeletal muscle repair mostly focused on promoting regeneration and inhibiting fibrosis . In particular, the transforming growth factor‐β (TGF‐β) was extensively studied for its promoting function on muscle fibrosis .…”

“…MicroRNA (miRs) is one of the numerous factors that participate in the manipulation of TGF‐β/Smad signalling pathway . They constitute a class of highly conserved, small endogenous noncoding RNA molecules with a length of ~25 bp that regulate gene expression at the posttranscriptional level .…”

MicroRNA-mRNA Co-sequencing Identifies Transcriptional and Post-transcriptional Regulatory Networks Underlying Muscle Wasting in Cancer Cachexia

“…Notably, miR-10b-5p was regulated at high levels in atrophying muscles ( Figure 4C). The differentially expressed miRNAs also included the miR-29b-3p, miR-146a-5p, miR-146b-5p, and miR-181c-3p, which have been previously studied in a skeletal muscle context [24,34,35].…”