Current progress in strategies to profile transcriptomic mA modifications.

Various methods have been developed so far for detecting -methyladenosine (mA). The total mA level or the mA status at individual positions on mRNA can be detected and quantified through some sequencing-independent biochemical methods, such as LC/MS, SCARLET, SELECT, and mA-ELISA. However, the mA-detection techniques relying on high-throughput sequencing have more effectively advanced the understanding about biological significance of mA-containing mRNA and mA pathway at a transcriptomic level over the past decade. Various SGS-based (Second Generation Sequencing-based) methods with different detection principles have been widely employed for this purpose. These principles include mA-enrichment using antibodies, discrimination of mA from unmodified A-base by nucleases, a fusion protein strategy relying on RNA-editing enzymes, and marking mA with chemical/biochemical reactions. Recently, TGS-based (Third Generation Sequencing-based) methods have brought a new trend by direct mA-detection. This review first gives a brief introduction of current knowledge about mA biogenesis and function, and then comprehensively describes mA-profiling strategies including their principles, procedures, and features. This will guide users to pick appropriate methods according to research goals, give insights for developing novel techniques in varying areas, and continue to expand our boundary of knowledge on mA.