Function Of MicroRNA

The advance in study of small RNAs brings us great excitation, mainly including siRNAs as promising tools for studying gene function or gene therapy and miRNAs, the endogenous small RNA molecule, playing important roles in regulation of life. Interestingly, there are substantial fraction of miRNAs located within the introns of annotated genes in the same orientation as the predicted mRNA. On the base of this fact, we have our try in attempt to find some interesting sequence in introns of certain genes.After screening introns of dozens of cancer genes, we found a specific sequence in introns of gene BRCA1, the RNAs of which can form stable hai-pin structure. This sequence of the small RNA was also found located in the introns of TNFRSF8 and PFKFB4 and could also be folded into perfect hairpin structure by mfold. The small RNAs share high paraogeneity in the three genes. Simultaneously high orthogeneity were found of the small RNAs in three species of human, rat and mouse.According to the result of Rt-PCR, we did a research of miRNA at the level of cell. We studied about the miRNA effecting the cell in proliferation, response to some drugs, defferenciation, and cell cycle. According to these result we could concluded that: miRNA can effect cell at several aspects: (1) it can effect tumor cell proliferation, and is possoble because of repression of the expression of CDC6, EEF1D and tert. (2) take part in repairing the DNA damage, and keeping the chromosome stability. (3) regulate the cell differectation and development, promoting the tumor cell differentiation, in which the cell grow bigger and secrete specific stuff such as lipid. (4) regulate the cell cycle.