RRP1 (ribosomal RNA processing 1) is a multifunctional RNA-binding protein with distinct roles in ribosome biogenesis and immune regulation. In ribosome biogenesis, RRP1 localizes to the nucleolus and is essential for early pre-rRNA processing, specifically catalyzing site 2 cleavage in internal transcribed spacer 1 (ITS1) during the conversion of the 90S pre-ribosomal particle into pre-40S and pre-60S subunits 1. This function involves competitive binding with fibrillarin and coordination with exonucleolytic activities to generate mature 28S rRNA 1. Beyond ribosome biogenesis, RRP1 functions as a post-transcriptional suppressor of inflammation by binding the nuclear thymidylate synthetase (TYMS) transcript and reducing TYMS expression in inflammatory macrophages, thereby inhibiting one-carbon metabolism-driven inflammation 2. Myeloid-specific RRP1 deficiency causes severe experimental arthritis with elevated pro-inflammatory cytokines, while RRP1 expression in rheumatoid arthritis patients inversely correlates with TYMS and IL-1β levels 2. Additionally, RRP1 homologs display redox-dependent functions in long-term memory formation through gene regulation mechanisms 3, and possess AP-endonuclease-like catalytic activities for nucleotide damage repair 4. These findings establish RRP1 as a critical regulator integrating ribosome biogenesis with metabolic control of inflammation.