miRT

MicroRNAs (miRNAs) are small endogeneous non-coding RNAs of about 22nt length. These short RNAs regulate the expression of mRNAs by hybridizing with their 3'-UTRs or by translational repression. They have been shown to take crucial roles in many biological processes. Many of the current studies are focused over how mature miRNAs regulate mRNAs, even though very limited knowledge is there about their transcriptional loci. Primary miRNAs (pri-miRs) are first transcribed from the DNA, followed by the formation of precursor miRNA (pre-miR) by endonucleases activity, which finally produces mature miRNAs. Unfortunately, the identification of the loci of pri-miRs, and the associated information about transcription start sites (TSSs) and promoters is still in progress. There are reported results concerning the TSSs of about 40% of the total mature miRNAs hitherto explored in human. This limited information, presented as the miRT database, is useful for further study on the regulation of miRNAs.