RNA 5-methylcytosine modification and its emerging role as an epitranscriptomic mark.

5-methylcytosine (m5C) is identified as an abundant and conserved modification in various RNAs, including tRNAs, mRNAs, rRNAs, and other non-coding RNAs. The application of high-throughput sequencing and mass spectrometry allowed for the detection of m5C at a single-nucleotide resolution and at a global abundance separately; this contributes to a better understanding of m5C modification and its biological functions. m5C modification plays critical roles in diverse aspects of RNA processing, including tRNA stability, rRNA assembly, and mRNA translation. Notably, altered m5C modifications and mutated RNA m5C methyltransferases are associated with diverse pathological processes, such as nervous system disorders and cancers. This review may provide new sights of molecular mechanism and functional importance of m5C modification.