In the early 1990s Victor Ambros’ laboratory, then at Harvard University, identified a transcript in Caenorhabditis elegans that contained a 22 nt noncoding RNA that they called lin-4. Ambros’ group discovered that the tiny lin-4 RNA bound to several places in the 3´ untranslated region (UTR) of the heterochronic gene lin-14 and that this served to regulate expression of that gene at the post-transcriptional level.
Calling this noncoding species a microRNA, Ambros’ discovery opened the door on a previously unsuspected world of small, noncoding, regulatory RNAs that, today, has grown to thousands of transcription units encompassing six distinct families of which at least one has been found in nearly every eukaryotic species examined.
Small RNAs are crucial elements in a host of cellular processes including development, apoptosis, genome organization, and several diseases, notably cancer. For this reason, numerous products, protocols, and software packages have been developed to aid in small RNA-expression profiling and target prediction.
However, little has been done in the way of aiding primary small RNA discovery. Only miRNAs display the thermodynamically stable hairpin structures that aid in in silico discovery and even this is limited to sequenced genomes. To address the need to be able to identify small RNAs in vitro in any species and in any tissue, Integrated DNA Technologies (IDT; www.idtdna.com) has developed a line of small RNA cloning aids. The centerpiece of this line is the miRCat™ small RNA cloning kit.