A spatiotemporal translatome of mouse tissue development

The precise regulation of gene expression in mammalian tissues during development results in their functional specification. Although previous transcriptomic and proteomic analyses have provided great biological insights into tissue-specific gene expression and the physiological relevance of these tissues in development, our understanding of translational regulation in developing tissues is lacking. In this study, we performed a spatiotemporally resolved translatome analysis of six mouse tissues at the embryonic and adult stages to quantify the effects of translational regulation and identify new translational components. We quantified the spatial and temporal divergences of gene expression and detected specific changes in gene expression and pathways underlying these divergences. We further showed that dynamic translational control can be achieved by modulating the translational efficiency, which resulted in the enhancement of tissue specificity during development. We also discovered thousands of actively translated upstream open reading frames (ORFs) that exhibited spatiotemporal patterns and demonstrated their regulatory roles in translational regulation. Furthermore, we identified known and novel micropeptides encoded by small ORFs from long noncoding RNAs that are functionally relevant to tissue development. Our data and analyses facilitate a better understanding of the complexity of translational regulation across tissue and developmental spectra and serve as a useful resource of the mouse translatome.