MicroRNA Is a Big Topic in Bio

Kristen Philipkoski reports in Wired News:

One of the tiniest entities in the human genome is becoming a very big deal in biology, with implications for the treatment of cancer, diabetes and brain disorders. MicroRNA, or miRNA, was considered relatively unimportant less than a decade ago. The tiny bits of RNA play a part in gene regulation, which involves how and when genes turn on and off. When the human genome proved to have fewer than 25,000 genes instead of the 100,000 or so that many scientists predicted, gene regulation became the focus of much attention. Suddenly it wasn’t the genes themselves that held the most intrigue, but the things that influence their behavior and the proteins that the gene-regulation process produces.

MiRNA seems to stifle the production of proteins exclusively — a function opposite that of its better-known relative, messenger RNA, or mRNA, which translates instructions from genes to create proteins. Researchers estimate there could be anywhere from 200 to 1,000 miRNAs — the range is wide because miRNAs are so small, making them difficult to detect. Gary Ruvkun, a Harvard University researcher and pioneer of miRNA research, has called the tiny entities “the biological equivalent of dark matter, all around us but almost escaping detection.” In a paper published in the Jan. 14 issue of Cell, David Bartel of the New York University School of Medicine predicted that miRNAs could regulate 30 percent of all human genes.

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