Polyuridylation

Polyuridylation, also called oligouridylation, is the addition of several uridine nucleotides to the 3' end of an RNA. Cytoplasmic poly polymerases can add uridine nucleotides to both coding and non-coding RNAs. This addition may occur throughout a variety of RNA types including mRNAs, small RNAs, miRNAs, siRNAs, guide RNAs, or piRNAs. Polyuridylation has been shown to play a role in gene regulation as an evolutionarily conserved process in eukaryotes.
One group of RNAs that can be polyuridylated are histone mRNAs that lack a poly(A) tail. Polyuridylation of a histone mRNA promotes its degradation, involving the exosome. Other RNAs in Arabidopsis and mouse have been seen to be polyuridinylated after cleavage.