Quantification of subcellular mRNA kinetics in mouse embryonic stem cells

In this work, we quantified mRNA flow rates between subcellular compartments in mouse embryonic stem cells. Combining metabolic RNA labeling, biochemical cell fractionation and RNA sequencing with mathematical modeling we were able to determine the kinetic rates of nuclear pre-, nuclear mature, cytosolic and membrane mRNA derived from more than 9000 protein-coding genes. For more than 5000 genes, we additionally estimated the transcript elongation rate. For most of the transcripts, mature nuclear half-lives are the longest, suggesting nuclear retention to be the rate-limiting step in the mRNA life cycle. Genes encoding transcription factors and immediate early genes possess fast kinetic rates, specifically a short nuclear half-life. Differentially localized mRNAs exhibit distinct combinations of rate constants, suggesting modular control within subcellular compartments. We show that membrane stability is high for membrane-localized mRNA and that cytosolic stability is high for cytosol-localized mRNA. Genes encoding target signals, such as signal peptides or transmembrane domains, have low cytosolic and high membrane half-lives with only slight differences between target signals. Nuclear-encoded mitochondrial proteins show long nuclear mature half-lives and otherwise similar features of cytoplasmic kinetics that do not resemble co-translational targeting to the mitochondria.