Abstract

Here we discuss the hypothesis that the RNA components of the Ro ribonucleoproteins (RNPs), the Y RNAs, can be processed into microRNAs (miRNAs). Although Ro RNPs, whose main protein components Ro60 and La are targeted by the immune system in several autoimmune diseases, were discovered many years ago, their function is still poorly understood. Indeed, recent data show that miRNA-sized small RNAs can be generated from Y RNAs. This hypothesis leads also to a model in which Ro60 acts as a modulator in the Y RNA-derived miRNA biogenesis pathway. The implications of these Y RNA-derived miRNAs, which may be specifically produced under pathological circumstances such as in autoimmunity or during viral infections, for the enigmatic function of Ro RNPs are discussed.