m 6 A demethylase ALKBH5 drives denervation-induced muscle atrophy by targeting HDAC4 to activate FoxO3 signalling

Skeletal muscle atrophy is a common clinical manifestation of various neurotrauma and neurological diseases. In addition to the treatment of primary neuropathies, it is a clinical condition that should be investigated. FoxO3 activation is an indispensable mechanism in denervation-induced muscle atrophy; however, upstream factors that control FoxO3 expression and activity have not been fully elucidated. N -methyladenosine (m A) methylation is a novel mode of epitranscriptional gene regulation that affects several cellular processes. However, the biological significance of m A modification in FoxO3-dependent atrophy is unknown. We performed gain-of-function and loss-of-function experiments and used denervation-induced muscle atrophy mouse model to evaluate the effects of m A modification on muscle mass control and FoxO3 activation. m A-sequencing and mass spectrometry analyses were used to establish whether histone deacetylase 4 (HDAC4) is a mediator of m A demethylase ALKBH5 regulation of FoxO3. A series of cellular and molecular biological experiments (western blot, immunoprecipitation, half-life assay, m A-MeRIP-qPCR, and luciferase reporter assays among others) were performed to investigate regulatory relationships among ALKBH5, HDAC4, and FoxO3. In skeletal muscles, denervation was associated with a 20.7-31.9% decrease in m A levels (P