MicroRNAs, small single-stranded RNA molecules that help regulate gene expression, may have an important role in embryonic patterning, suggests a study in Nature this week.
Two microRNAs help restrict the size of the Spemann's organizer, an important structure seen early in development that influences cell fate and patterning, Stefano Piccolo and colleagues report. The microRNAs, called miR-15 and miR-16, are distributed asymmetrically along the dorsoventral axis of Xenopus embryos, where they asymmetrically influence the expression of a particular receptor, called Acvr2a. This means that the receptor's ligand - a protein belonging to the transforming growth factor-beta family (TGF-beta) - is preferentially expressed along one side of the developing embryo also.
The study is the first to link inhibitory microRNAs, the Spemann's organizer and TGF-beta proteins, which are known to have a key role in development and the maintenance of adult tissue. Furthermore, it provides an elegant mechanism for establishing asymmetries in vertebrate embryos.
Stefano Piccolo (University of Padua, Italy)
Abstract available online.
(C) Nature press release.
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