Unfolding the symbiosis of AID, chromatin remodelers, and epigenetics-The ACE phenomenon of antibody diversity.

Activation-induced cytidine deaminase (AID) is responsible for the initiation of somatic hypermutation (SHM) and class-switch recombination (CSR), which result in antibody affinity maturation and isotype switching, thus producing pathogen-specific antibodies. Chromatin dynamics and accessibility play a significant role in determining AID expression and its targeting. Chromatin remodelers contribute to the accessibility of the chromatin structure, thereby influencing the targeting of AID to Ig genes. Epigenetic modifications, including DNA methylation, histone modifications, and miRNA expression, profoundly impact the regulation of AID and chromatin remodelers targeting Ig genes. Additionally, epigenetic modifications lead to chromatin rearrangement and thereby can change AID expression levels and its preferential targeting to Ig genes. This interplay is symbolized as the ACE phenomenon encapsulates three interconnected aspects: AID, Chromatin remodelers, and Epigenetic modifications. This review emphasizes the importance of understanding the intricate relationship between these aspects to unlock the therapeutic potential of these molecular processes and molecules.