Transcriptional regulation of mammalian miRNA genes

MicroRNAs (miRNAs) are members of a growing family of non-coding transcripts, 21–23 nucleotides long, which regulate a diverse collection of biological processes and various diseases by RNA-mediated gene-silencing mechanisms. While currently many studies focus on defining the regulatory functions of miRNAs, few are directed towards how miRNA genes are themselves transcriptionally regulated. Recent studies of miRNA transcription have elucidated RNA polymerase II as the major polymerase of miRNAs, however, little is known of the structural features of miRNA promoters, especially those of mammalian miRNAs. Here, we review the current literature regarding features conserved among miRNA promoters useful for their detection and the current novel methodologies available to enable researchers to advance our understanding of the transcriptional regulation of miRNA genes.