Steroid receptors and microRNAs: relationships revealed.

MicroRNAs (miRNAs) are small non-coding RNAs that serve as post-transcriptional regulators of gene expression. They work predominantly by binding to complementary sequences in target messenger RNA (mRNA) 3' untranslated regions (UTRs) where they prevent translation or cause degradation of the message. Steroid hormone receptors (SHRs) are ligand-activated transcription factors that regulate genes in steroid responsive tissues. Recent studies demonstrate that SHRs regulate miRNAs, and in turn, miRNAs can regulate SHR expression and function. Mounting evidence indicates that miRNAs are intimately involved with SHRs, as they are with other transcription factors, often in double negative feedback loops. Investigators are just beginning to expose the details of these complex relationships and reveal the extent to which miRNAs are involved with SHRs in normal physiology and the pathobiology of steroid hormone responsive tissues.