In animal embryos, control of development is passed from exclusively maternal gene products to those encoded by the embryonic genome in a process referred to as the maternal-to-zygotic transition (MZT). We show that the RNA-binding protein, ME31B, binds to and represses the expression of thousands of maternal mRNAs during the Drosophila MZT. However, ME31B carries out repression in different ways during different phases of the MZT. Early, it represses translation while, later, its binding leads to mRNA destruction, most likely as a consequence of translational repression in the context of robust mRNA decay. In a process dependent on the PNG kinase, levels of ME31B and its partners, Cup and Trailer Hitch (TRAL), decrease by over 10-fold during the MZT, leading to a change in the composition of mRNA–protein complexes. We propose that ME31B is a global repressor whose regulatory impact changes based on its biological context.

Every step in the life cycle of an RNA transcript provides opportunity for regulation. One important aspect of post-transcriptional control is the regulation of RNA stability. Of the many strategies for determining mRNA stability, transcription inhibition and metabolic labeling have proved the most amenable to high-throughput analysis and have opened the door to dissecting mRNA decay transcriptome-wide. Here, we describe experimental and computational methods to determine transcriptome-wide RNA stabilities using both pharmacological inhibition of transcription and metabolic labeling. To aid in the analysis of these experiments, we discuss key characteristics of high-quality experiments and address other experimental and computational considerations for the analysis of mRNA stability. Broader application of these approaches will further our understanding of mRNA decay and illuminate its contribution to different biological processes.

BackgroundAll mRNAs are bound in vivo by proteins to form mRNA–protein complexes (mRNPs), but changes in the composition of mRNPs during posttranscriptional regulation remain largely unexplored. Here, we have analyzed, on a transcriptome-wide scale, how microRNA-mediated repression modulates the associations of the core mRNP components eIF4E, eIF4G, and PABP and of the decay factor DDX6 in human cells.ResultsDespite the transient nature of repressed intermediates, we detect significant changes in mRNP composition, marked by dissociation of eIF4G and PABP, and by recruitment of DDX6. Furthermore, although poly(A)-tail length has been considered critical in post-transcriptional regulation, differences in steady-state tail length explain little of the variation in either PABP association or mRNP organization more generally. Instead, relative occupancy of core components correlates best with gene expression.ConclusionsThese results indicate that posttranscriptional regulatory factors, such as microRNAs, influence the associations of PABP and other core factors, and do so without substantially affecting steady-state tail length.Electronic supplementary materialThe online version of this article (doi:10.1186/s13059-017-1330-z) contains supplementary material, which is available to authorized users.