The Role of Dynamic m6 A RNA Methylation in Photobiology.

N6 -methyladenosine (m6 A) is the most abundant internal RNA modification among numerous post-transcriptional modifications identified in eukaryotic mRNA. m6 A modification of RNA is catalyzed by the "writer" m6 A methyltransferase enzyme complex, consisting of METTL3, METTL14, WTAP and KIAA1429. The m6 A modification is reversible and can be removed by "eraser" m6 A demethylase enzymes, namely, FTO and ALKBH5. The biological function of m6 A modification on RNA is carried out by RNA-binding effector proteins called "readers." Varied functions of the reader proteins regulate mRNA metabolism by affecting stability, translation, splicing or nuclear export. The epitranscriptomic gene regulation by m6 A RNA methylation regulates various pathways, which contribute to basic cellular processes essential for cell maintenance, development and cell fate, and affect response to external stimuli and stressors. In this review, we summarize the recent advances in the regulation and function of m6 A RNA methylation, with a focus on UV-induced DNA damage response and the circadian clock machinery. Insights into the mechanisms of m6 A RNA regulation and post-transcriptional regulatory function in these biological processes may facilitate the development of new preventive and therapeutic strategies for various diseases related to dysregulation of UV damage response and circadian rhythm.