miR-21的研究进展

Advance in the Research of miR-21

小RNA或微小RNA（microRNAs，miRNAs）是内源性的非编码小RNA，对基因表达进行转录后的负向调控。目前已发现数以千计的miRNA，其中只有少数miRNA功能得到了确定，而绝大部分还是未知。相对于其他生物，人类miRNA功能的研究更为复杂。miR-21是较早发现的人类miRNA之一，因其较为明确的存在背景，而成为人类miRNA功能研究中的重要工具。通过研究miR-21，人们对miRNA的理解不断深入。

miRNAs are a class of small noncoding RNAs consisting of 19-to 25- nucleotides, which negatively regulate target mRNA on post-transcriptional level. At present, more than a thousand of miRNAs have been cloned. Except some pioneer miRNAs, the function of most miRNAs still left unkown. Compared with other species, the function of human miRNA is more complex, miR-21, one of the early discovered miRNAs in human cells, over-expressed in HeLa cells, is a popular model applied in functional study of human miRNAs. By further study, we have a more extensive view on miRNAs.