Managing microRNAs

Two independent, upcoming G&D papers lend new insight into the expression of microRNAs and their targets during vertebrate development. Dr. David Bartel and colleagues describe a novel experimental system for genome-wide quantitative analysis of miRNA target expression in miRNA-expressing cells. They found that in the developing zebrafish embryo, miRNA targets are commonly expressed at lower levels in miRNA-expressing cells, suggesting that miRNAs work in concert with other regulatory processes to dampen target gene expression in specific miRNA-expressing cells.

Separately, Dr. Antonio Giraldez and clleagues detail their identification of the muscle-specific miRNA targets in the zebrafish embryo. They report that miR-1 and miR-133 are they key muscle regulatory miRNAs, and that they function by mediating actin organization in the developing muscle.