Targeted Demethylation of the TGFβ1 mRNA Promotes Myoblast Proliferation via Activating the SMAD2 Signaling Pathway

Abstract

Recent evidence suggested that N6-methyladenosine (m6A) methylation can determine m6A-modified mRNA fate and play an important role in skeletal muscle development. It was well known that transforming growth factor beta 1 (TGFβ1) is involved in a variety of cellular processes, such as proliferation, differentiation, and apoptosis. However, little is known about the m6A-mediated TGFβ1 regulation in myogenesis. Here, we observed an increase in endogenous TGFβ1 expression and activity during myotube differentiation. However, the knockdown of TGFβ1 inhibits the proliferation and induces cell apoptosis of myoblast. Moreover, we found that m6A in 5′-untranslated regions (5′UTR) of TGFβ1 promote its decay and inhibit its expression, leading to the blockage of the TGFβ1/SMAD2 signaling pathway. Furthermore, the targeted specific demethylation of TGFβ1 m6A using dCas13b-FTO significantly increased the TGFβ1-mediated activity of the SMAD2 signaling pathway, promoting myoblast proliferation. These findings suggest that TGFβ1 is an essential regulator of myoblast growth that is negatively regulated by m6A. Overall, these results highlight the critical role of m6A-mediated post-transcriptional regulation in myogenesis.

Epigenetic control of skeletal muscle atrophy

“…It was observed that silencing FTO impaired mitochondrial biogenesis and energy production, attributable to the downregulation of the mTOR and PGC-1α [ 159 ]. Further investigation revealed that m6A modification of the 5′UTR of TGFβ1 mRNA facilitates its degradation, with FTO influencing these modifications to hinder myoblast differentiation [ 160 ]. Experiments in genetically engineered mice demonstrated that FTO overexpression did not alter skeletal muscle mass [ 220 ], whereas FTO deficiency compromised skeletal muscle development [ 159 ].…”