Functions of animal microRNA-encoded peptides: the race is on!

Short open reading frame (sORF)-encoded peptides (SEPs) recently emerged as new key players in biology. Pioneering work first established that sORFs encoded by long non-coding RNAs (lncRNAs) are efficiently translated and produce functional peptides. In plants, primary transcripts of microRNAs (pri-miRNAs) also produce sORF-encoded peptides called miPEPs, which are involved in specific transcriptional autoregulatory feedback loops (Lauressergues et al, 2015). To what extend are such mechanisms conserved in other species, especially in animals? In this issue of EMBO reports, Zhou et al show that pri-miR-31 encodes a miPEP promoting Treg differentiation and downregulating pri-miR-31 expression (Zhou et al, 2022).