Exiqon

MicroRNA Expression

MicroRNAs (miRNAs) are an important class of short endogenous RNAs that act as post-transcriptional regulators of gene expression by base-pairing with 3' untrnaslated region of target mRNAs. The short (~22 nt) mature miRNAs are processed sequentially from longer hairpin transcripts by the RNAse III ribonucleases. According to the miRBase database release 9.0 more than 4000 microRNAs have been annotated in vertebrates, invertebrates and plants. Some miRNAs have multiple loci in the genome and occasionally, several miRNA genes are arranged in tandem clusters. Recent bioinformatic predictions combined with array analyses, small RNA cloning and Northern blot validation indicate that the total number of miRNAs in vertebrate genomes is significantly higher than previously estimated and maybe as many as 1000. http://www.exiqon.com/microrna