Ascorbic acid reprogrames epigenome and epitranscriptome by recycling Fe (III) into Fe (II) in the catalytic cycle of dioxygenases (m6A)
Ascorbic acid has been reported to stimulate DNA iterative oxidase TET enzymes, Jumonji C-domain-containinghistone demethylase and potentially RNA m6A demethylase FTO and ALKBH5 as a cofactor. Although ascorbic acid has been widely investigated in reprogramming DNA and histone methylation status in vitro, in cell lines and mouse models, its specific role in the catalytic cycle of dioxygenases remains enigmatic. Here we systematically investigated the stimulation of ascorbic towards TET2, ALKBH3, histone demethylases and FTO. We find that ascorbic acid reprograms epitranscrip-tome by erasing the hypermethylated m6A sites. Biochemistry and Electron spin resonance (ESR) assays demonstrate that ascorbic acid enters the active pocket of dioxygenases, reduces Fe (III), either incorporated upon protein synthesis or generated upon rebounding the hydroxyl radical during oxidation, into Fe (II). Finally, we propose a new model for the catalytic cycle of dioxygenases by adding in the essential dynamic cofactor, ascorbic acid. Ascorbic acid refreshes and regenerates inactive dioxygenase through recycling Fe (III) into Fe (II) in a dynamic “hit-and-run” manner. Overall design: Comparation m6A profiling analysis of RNA-seq data  after Ascorbic acid treatment