New study examines microRNA’s in plants and animals

CAMBRIDGE, Mass. — As genes and proteins continue to take center stage in molecular biology, molecules called microRNAs are starting to make inroads. These microRNAs, which are unusually small when compared to other RNAs in the cell, have captured the attention of biologists with their capacity to regulate genes, an ability that one day may have therapeutic value. Scientists suspected that microRNAs behave differently in plants than in animals, but new findings from researchers in the lab of Whitehead Member and MIT professor David Bartel show that this isn’t always the case.

MicroRNAs are gene silencers that disrupt a gene’s ability to produce protein. In plants, they often do this by directing the destruction of messenger RNAs, which are molecules that procure from the genes the information needed to make proteins and deliver this information to the machinery that makes the proteins. In mammalian cells the process is less clear, but microRNAs manage to repress the protein-making process without damaging the messenger RNA.

In a paper published in a recent issue of the journal Science, Whitehead researchers report a significant exception to this rule. Here, the authors describe a family of microRNAs that, in mammals, regulates a particular gene by destroying the messenger RNA—the mechanism previously seen only with plant microRNAs.

“The gene belongs to a very significant family of genes that are responsible for laying out the bodily structure of vertebrates,” says Soraya Yekta, lead author on the paper and a graduate student in Bartel’s lab. The class of genes targeted by this microRNA determines the position of a vertebrate embryo’s organs or tissues, even specific limbs. “The fact that we’re implicating microRNAs puts them at the center of embryonic development.”

Yekta’s next step is to work together Harvard University researchers to discover what happens during the embryonic development of mice when the function of this microRNA is disrupted.

Citation

Yekta, S., Shih, I. H., & Bartel, D. P. (2004). MicroRNA-directed cleavage of HOXB8 mRNA. Science, 304(5670), 594-596.