Quantitative Proteomics Identifies Profilin-1 as a Pseudouridine-Binding Protein

Pseudouridine (Ψ) is the most abundant RNA modification in nature; however, the exact biological functions of Ψ remain largely elusive. By employing an unbiased quantitative proteomics method, we identified multiple candidate reader proteins of Ψ in RNA, including a cytoskeleton protein profilin-1, whose mutations are linked with amyotrophic lateral sclerosis (ALS). We purified recombinant PFN1 and showed that it can bind directly and selectively to Ψ-containing RNA. We also found that PFN1 binds to thousands of transcripts in human cells, including a known Ψ site in the mRNA of TPI1. We showed that PFN1-Ψ interaction is crucial for regulating the stability and translation efficiency of TPI1 mRNA. Together, our data unveiled PFN1 as a reader protein of Ψ in RNA and illustrated the functions of PFN1-Ψ interaction in modulating the stability and translation efficiency of TPI1 mRNA, which provides new insights into the functions of Ψ in RNA biology and lays a strong foundation for the discovery of new mechanisms in disease pathogenesis Transcriptome-wide profiling analysis of FLAG-PFN1 in HEK293T cells