LAUSR

The mammalian cleavage factor I subunit CFIm25 (NUDT21) binds to the UGUA sequences of precursor RNAs. Traditionally, CFIm25 is known to facilitate 3′ end formation of pre‐mRNAs resulting in the formation of polyadenylated transcripts. Recent studies suggest that CFIm25 may be involved in the cyclization and hence generation of circular RNAs (circRNAs) that contain UGUA motifs. These circRNAs act as competing endogenous RNAs (ceRNAs) that disrupt the ceRNA–miRNA–mRNA axis. Other emerging roles of CFIm25 include regulating both alternative splicing and alternative polyadenylation (APA). APA generates different sized transcripts that may code for different proteins, or more commonly transcripts that code for the same protein but differ in the length and sequence content of their 3′ UTRs (3′ UTR‐APA). CFIm25 mediated global changes in 3′ UTR‐APA affect human physiology including spermatogenesis and the determination of cell fate. Deregulation of CFIm25 and changes in 3′ UTR‐APA have been implicated in several human diseases including cancer. In many cancers, CFIm25 acts as a tumor suppressor. However, there are some cancers where CFIm25 has the opposite effect. Alterations in CFIm25‐driven 3′ UTR‐APA may also play a role in neural dysfunction and fibrosis. CFIm25 mediated 3′ UTR‐APA changes can be used to generate specific signatures that can be used as potential biomarkers in development and disease. Due to the emerging role of CFIm25 as a regulator of the aforementioned RNA processing events, modulation of CFIm25 levels may be a novel viable therapeutic approach.