Enlightening epigenetics: optochemical tools illuminate the path.

Optochemical tools have become potent instruments for understanding biological processes at the molecular level, and the past decade has witnessed their use in epigenetics and epitranscriptomics (also known as RNA epigenetics) for deciphering gene expression regulation. By using photoresponsive molecules such as photoswitches and photocages, researchers can achieve precise control over when and where specific events occur. Therefore, these are invaluable for studying both histone and nucleotide modifications and exploring disease-related mechanisms. We systematically report and assess current examples in the field, and identify open challenges and future directions. These outstanding proof-of-concept investigations will inspire other chemical biologists to participate in these emerging fields given the potential of photochromic molecules in research and biomedicine.