Long non-coding RNA MFAT1 promotes skeletal muscle fibrosis by modulating the miR-135a-5p-Tgfbr2/Smad4 axis as a ceRNA.

Fibrosis after skeletal muscle injury is common in sports and can cause irreversible damage to the biomechanical properties of skeletal muscle. Long non-coding RNAs (lncRNAs) have been validated to act as important modulators in the fibrosis of various organs. Here, we reported a novel lncRNA (the skeletal muscle fibrosis-associated transcript 1, lnc-MFAT1), which was highly expressed in skeletal muscle fibrosis. We demonstrate that lnc-MFAT1 knockdown can reduce TGFβ-induced fibrosis in vitro and attenuate skeletal muscle fibrosis after acute contusion in mice. Further study showed that lnc-MFAT1 acted as a competitive endogenous RNA of miR-135a-5p. Besides, the miR-135a-5p inhibition obviously promoted TGFβ-induced fibrosis in vitro via enhancing its target genes Tgfbr2/Smad4. Moreover, we discovered that lnc-MFAT1 regulates Tgfbr2/Smad4 expression by sponging miR-135a-5p to exert competing endogenous RNA function, resulting in TGFβ pathway activation. In conclusion, our study identified a crucial role of lnc-MFAT1-miR-135a-Tgfbr2/Smad4 axis in skeletal muscle fibrosis, providing a promising treatment option against skeletal muscle fibrosis.