Multidirectional interplay between nuclear receptors and microRNAs

Nuclear receptors (NRs) form one of the largest superfamilies of transcription factors in metazoans. MicroRNAs (miRNAs) are small non-coding RNAs that bind the 3' untranslated region (3'UTR) of target mRNAs to reduce their stability and/or translation. miRNAs can directly regulate the protein output of target NR mRNAs, and, conversely, the expression of miRNAs can be modulated by NRs at the transcriptional level. At least one NR also regulates the posttranscriptional maturation of miRNAs by interacting with miRNA processing factors via NR co-regulators. Moreover, miRNAs regulate NR signaling by targeting the mRNAs of NR co-regulators and target genes. This complex set of interactions also leads to an extensive network of feedback and feedforward regulatory loops.