Single Cell Proteomics Reveal that Temporal Changes in Transcription Factors Determine Cell-Fate

Hematopoiesis provides an accessible system for studying the principles underlying cell-fate decisions in stem cells. Proposed models of hematopoiesis suggest that quantitative changes in lineage-specific transcription factors (LS-TFs) underlie cell-fate decisions. However, evidence for such models is lacking as TFs levels are typically measured via RNA expression rather than by analysing protein abundance. Here, we used single-cell mass-cytometry and absolute quantification by mass-spectrometry to capture the temporal dynamics of TF protein expression in individual cells during human erythropoiesis. We found that LS-TFs from alternate lineages are co-expressed, as proteins, in individual early progenitor cells and quantitative changes of LF-TFs occur gradually, rather than abruptly to direct cell-fate decisions. Importantly, upregulation of a megakaryocytic TF in early progenitors is sufficient to deviate cells from an erythroid to a megakaryocyte trajectory showing that quantitative changes in protein abundance of LS-TFs in progenitors can determine alternate cell-fates.