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In recent years it has become apparent that microRNAs (miRNAs) are common feature of eukaryotic genomes. The functional products of these non-canonical genes are small, ~22nt RNAs that negatively regulate translation. Targeting of mRNAs occurs when a miRNA base pairs with complementary sequence elements located in the 3 untranslated region of mRNAs. Currently hundreds of miRNA species have been described. However, due to the imprecise pairing between miRNAs and their targets, the functional role of most miRNAs remains unknown. We approached this problem in zebrafish by using a combination of phenotypic analysis and reporter constructs. We determined that miR-214 targets su(fu), a regulator of hedgehog signaling, and that this is critical for appropriate muscle cell specification during somitogenesis. Additionally, we show that the miR-8 family of miRNAs targets a regulator of membrane trafficking, nherf1. This regulation is a critical component of the osmotic stress response. Together, we reveal diverse roles for miRNAs in zebrafish, and demonstrated the feasibility of using this model system to understand miRNA function. |
