rRNAderived

rRNA-derived fragments (rRFs), also referred to as rRNA-derived small RNAs (rsRNAs), are small non-coding RNA species that originate from ribosomal RNA transcripts. In eukaryotes, these sources include the 5S, 5.8S, 18S, and 28S rRNAs, with analogous rRNA components present in other domains of life. rRFs are produced by cellular ribonucleases and can accumulate under various conditions, including development, stress, infection, and aging. They are distinct from intact ribosomal RNA molecules and from other well-characterized small RNAs.

Biogenesis and diversity of rRFs are heterogeneous. Some rRFs arise from specific cleavage events, yielding defined 5' fragments, 3' fragments, or internal fragments, while others may reflect partial degradation of mature rRNA. The relative abundance and exact origins of rRFs can vary by organism, tissue, and physiological state. In sequencing data, rRFs pose analytical challenges due to the multi-copy, highly abundant nature of rRNA genes.

Potential functions attributed to rRFs are diverse and continue to be explored. Proposed roles include modulation of gene expression and translation, involvement in ribosome biogenesis, and participation in cellular stress responses. rRFs can associate with RNA-binding proteins and, in some contexts, influence RNA stability or translation, though functional evidence is strongest for a minority of characterized fragments. Distinguishing functional rRFs from degradation products remains a methodological and interpretive challenge.

Detection and study of rRFs rely on small RNA sequencing, specialized alignment strategies to account for rRNA gene repeats, and independent validation methods such as northern blotting or targeted assays. In health and disease, rRF profiles have been observed to change in certain cancers, neurodegenerative conditions, and developmental contexts, prompting consideration of rRFs as potential biomarkers alongside a broader interest in ribosome-associated RNA biology.