MicroRNAs and Developmental Robustness: A New Layer Is Revealed

In an elegant study in PLoS Biology, the Cohen laboratory describes a conserved miRNA family—miR-263a/b—that is expressed in the mechanosensory cells of the developing Drosophila eye and that plays a role in protecting fly bristles from apoptosis during the pruning event that forms the mature organ. The researchers show that in miR-263a/b deletion mutants’ loss of bristles appears to be sporadic and excessive. The activity of these anti-apoptotic miRNAs appears to be to ensure that a sufficient number of interommatidial bristles are protected during the developmentally programmed wave of cell death that prunes the tissue in order to produce the correct pattern of the adult retina. Based on the observation that flies deficient for these miRNAs exhibit random bristle loss, the Cohen laboratory propose that these miRNAs play a protective role against excess apoptosis and thereby support robustness in the development of this complex organ. Interestingly, miR-263a/b are members of a conserved family of miRNAs that are expressed in peripheral sense organs across the animal kingdom and therefore may play a similar role in ensuring developmental robustness in other organisms.