What are micro RNAs? Micro RNAs (miRNAs) are small non-coding RNAs involved in regulating messenger RNA (mRNA) translation. Over 1000 miRNAs have been identified that control approximately 60% of protein coding genes1. MiRNAs are on average 23 nucleotides long, with nucleotides 2–7 serving as the seed region. The seed region is required for specific mRNA interactions, and mutations occur in this region that can disrupt miRNA, Watson-Crick base pairing of mRNA2. The mRNA is stabilized in the cytoplasm by adding a 5' cap and a 3' polyadenine tail, which prevents degradation by ribonucleases. MiRNA binding can cause 3 events to occur; deadenylation, decapping and degradation from 5' to 3'1. Often in the 3' untranslated region (UTR) there are AU-rich elements (ARE) when the miRNA together with Argonaute 1, Argonaute 2 and Dicer1 is bound allows rapid decay of mRNA1.2. Biogenesis of miRNAsMiRNAs can be transcribed from their own genes; often there are clusters of these miRNA genes, for example C19MC, which is the largest human cluster3. Another place where miRNAs are encoded is within the introns of other genes. MiRNAs are transcribed using RNA polymerase II or III4,5, this depends on the specific promoter or terminator sequences for each gene. The new transcript is called a primary miRNA (pri-miRNA) and must undergo processing before it can regulate the mRNA. While in the nucleus the pri-miRNA undergoes the first cleavage, which is catalyzed by Drosha, figure 1. Drosha is part of the RNase III family of enzymes and cleaves the transcript by 11 base pairs from the double-stranded/single-stranded RNA junction3 . In order for the cleavage to be accurate, a molecular ruler in the form of Pasha (p...... middle of paper ......t leads to a truncated TRBP. Cell lines showing this mutated TRBP also had extremely high levels lows of Dicer. When wild-type TRBP was restored in tumor cell lines, Dicer expression increased to WT16 levels. A study of nearly 300 primary human colorectal (sporadic or familial) or gastric tumors ( sporadic), of which 25.4% had mutant TRBP, and was higher in familial colorectal cancers at 43.1.4 AngiogenesisThe process of angiogenesis is the development of blood vessels all higher organisms, since oxygen is not able to diffuse throughout the body, but must be transported to cells far from the lungs. One of the main systems that controls angiogenesis and maintenance of blood vessels is angiopoietin- TIE17 and TIE1 are receptor tyrosine kinases that have extracellular domains similar to those of EGF and Ig.18.