Most developmental events require the precise control of gene expression,and RNA-binding protein-mediated post-transcriptional processes play an important role in such control. Now, Masanori Taira and colleagues identify a novel post-transcriptional control mechanism in Xenopus that centres on the RNA-binding protein Mex3b (see ). The mex3b mRNA contains a long, evolutionarily conserved 3′UTR(3′LCU), which, the authors report, promotes mRNA translation and destabilisation. Mex3b promotes the destabilisation of its own mRNA by binding to its 3′LCU, thus forming an autoregulatory negative-feedback loop, the in vivo presence of which the researchers demonstrate through mex3boverexpression and knockdown experiments. They also reveal a role for Mex3b in neural plate patterning that involves fibroblast growth factor (FGF)signalling. As Mex3b levels affect FGF responsiveness, and as the mRNAs of the FGF signalling components sdc2 and ets1 appear to be direct Mex3b targets, the authors suggest that the tightly controlled, autoregulated expression levels of mex3b in turn regulate FGF signalling during neural patterning.
