What are micro RNAs? Micro RNAs (miRNAs) are small non-coding RNAs that participate in the regulation of messenger RNA (mRNA) translation. More than 1,000 miRNAs have been identified, controlling approximately 60% of protein-coding genes1. MiRNAs are on average 23 nucleotides long, with nucleotides 2 to 7 serving as the seed region. The seed region is required for specific mRNA interactions and mutations occur in this region, it can disrupt miRNA, Watson-Crick2 base pairing of mRNA. The mRNA is stabilized in the cytoplasm by adding a 5' cap and a 3' poly adenine tail, which prevents degradation by ribonucleases. MiRNA binding can cause 3 events; 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 with Argonaute 1, Argonaute 2 and Dicer1 is bound, which allows rapid decay of the mRNA1.2 . miRNA biogenesis MiRNAs can be transcribed from their own genes; There are often clusters of these miRNA genes, for example C19MC, which is the largest human cluster3. Another place where miRNAs are encoded is in the introns of other genes. MiRNAs are transcribed using RNA polymerase II or III4,5, depending on the specific promoter or terminator sequences of 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 a member of the RNase III family of enzymes and cleaves all 11 base pairs of the RNA junction transcript double strand/single strand3. For cleavage to be precise, a Pacha-shaped molecular ruler (p...... middle of paper ......t leads to truncated TRBP. Cell lines that exhibited this mutated TRBP also had lower levels extremely low levels of Dicer When wild-type TRBP was restored in cancer cell lines, Dicer expression increased to WT16 levels A study of nearly 300 primary human colorectal cancers (sporadic or familial). or gastric (sporadic), among these 25.4%, showed mutant TRBP, and it was highest in familial colorectal cancers at 43.3%16.1.4 AngiogenesisThe process of angiogenesis is the development of vessels. blood It is vital for all higher organisms, because oxygen is not able to diffuse throughout the body, but must be transported to cells far from the lungs. and maintaining blood vessels is angiopoietin-TIE17 and TIE2 are tyrosine kinase receptors that have extracellular domains similar to those of EGF and Ig.18.