Dynamic rRNA modifications as a source of ribosome heterogeneity.

Ribosomal RNAs (rRNA) are the most abundant RNA molecules in almost all cell types. The general consensus in the field is that rRNA modifications are largely species-specific, with most previous works and databases solely stratifying modifications by the species of origin, without taking other levels of complexity into account. However, new evidence has emerged suggesting dynamic rRNA modifications may have additional layers of complexity and might play an important role in development and disease. In this review article, we summarize recent evidence supporting heterogeneity and dynamics in rRNA modifications in diverse biological contexts, challenging the simplistic view of 'one-species-one-rRNA-modification-pattern'. Moreover, we highlight how rRNA modification dynamics have been studied to date and how long-read sequencing methods can significantly improve our understanding of this largely unexplored yet highly abundant RNA family, across tissues, developmental stages, and diseases.