Ythdf2-mediated STK11 mRNA decay supports myogenesis by inhibiting the AMPK/mTOR pathway

Abstract

An emerging research focus is the role of m⁶A modifications in mediating the post-transcriptional regulation of mRNA during mammalian development. Recent evidence suggests that m⁶A methyltransferases and demethylases play critical roles in skeletal muscle development. Ythdf2 is a m⁶A "reader" protein that mediates mRNA degradation in an m⁶A-dependent manner. However, the specific function of Ythdf2 in skeletal muscle development and the underlying mechanisms remain unclear. Here, we observed that Ythdf2 expression was significantly upregulated during myogenic differentiation, whereas Ythdf2 knockdown markedly inhibited myoblast proliferation and differentiation. Combined analysis of high-throughput sequencing, Co-IP, and RIP assay revealed that Ythdf2 could bind to m⁶A sites in STK11 mRNA and form an Ago2 silencing complex to promote its degradation, thereby regulating its expression and consequently, the AMPK/mTOR pathway. Furthermore, STK11 downregulation partially rescued Ythdf2 knockdown-induced impairment of proliferation and myogenic differentiation by inhibiting the AMPK/mTOR pathway. Collectively, our results indicate that Ythdf2 mediates the decay of STK11 mRNA, an AMPK activator, in an Ago2 system-dependent manner, thereby driving skeletal myogenesis by suppressing the AMPK/mTOR pathway. These findings further enhance our understanding of the molecular mechanisms underlying RNA methylation in the regulation of myogenesis and provide valuable insights for conducting in-depth studies on myogenesis.

Keywords: Myogenesis; RNA degradation; STK11; Ythdf2; m(6)A modification.