Nuclear 2'-<i>O</i>-methylation regulates RNA splicing through its binding protein FUBP1.

Gao, Boyang; Jiang, Bochen; Zou, Zhongyu; Liu, Bei; Liu, Weijin; Chen, Li; Zhang, Lisheng; He, Chuan · Sci Adv · 2025

basic_science · Level V

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Abstract

2'-<i>O</i>-methylation (N<sub>m</sub>) is an abundant RNA modification exists on different mammalian RNA species. However, potential N<sub>m</sub> recognition by proteins has not been extensively explored. Here, we used RNA affinity purification, followed by mass spectrometry to identify N<sub>m</sub>-binding proteins. The N<sub>m</sub>-binding protein candidates exhibit enriched binding at known N<sub>m</sub> sites. Some candidates display nuclear localization and functions. We focused on the splicing factor FUBP1. Electrophoretic mobility shift assay validated preference of FUBP1 to N<sub>m</sub>-modified RNA. As FUBP1 predominantly binds intronic regions, we profiled N<sub>m</sub> sites in chromatin-associated RNA (caRNA) and found N<sub>m</sub> enrichment within introns. Depletion of N<sub>m</sub> led to skipped exons, suggesting N<sub>m</sub>-dependent splicing regulation. The caRNA N<sub>m</sub> sites overlap with FUBP1-binding sites, and N<sub>m</sub> depletion reduced FUBP1 occupancy on modified regions. Furthermore, <i>FUBP1</i> depletion induced exon skipping in N<sub>m</sub>-modified genes, supporting its role in mediating N<sub>m</sub>-dependent splicing regulation. Overall, our findings identify FUBP1 as an N<sub>m</sub>-binding protein and uncover previously unrecognized nuclear functions for RNA N<sub>m</sub> modification.

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