MicroRNA, or miRNA, is a single-stranded regulatory RNA only 20-25 nucleotides long. It is thought to regulate the expression of other genes.
MicroRNA is transcribed from DNA, but not translated into protein; its DNA encoder also includes an approximate reverse component. Both these halves are encoded, and the miRNA formed bends to form a double-strand RNA hairpin-shaped loop. This is called a primary microRNA, or pri-miRNA. The resultant strand is transported out of the nucleus into the cytoplasm, and the mature RNA attached to the microRNA is released.
MicroRNA seems to function in gene regulation, and are complementary to some part of one or more messenger RNAs. It also triggers the degradation of messenger RNA, and may also target methylation of genomic sites corresponding to targeted mRNA.
MicroRNA seems to have links with some types of cancer. A surplus of miRNA can cause the development of cancers related to excess c-myc protein. Other microRNA inhibit the E2F1 protein that regulates cell proliferation. With further study, doctors may be able to target treatments to specific microRNA issues based on the original tissue type of the miRNA's genesis, creating tailored cancer treatments.
Web Resources On microRNA
microRNAs: Definition & Overview
Book Resources On microRNA
Microrna Protocols by Shao-Yao Ying (ed)
microRNA: Biology, Function & Expression by Clarke & Sanseau