Ming Yang

Single-cell proteomics illuminated new mechanisms of mammalian development. We found that spatially polarized protein distributions and intracellular protein gradients emerge during the earliest stages of mammalian embryogenesis and help bias subsequent cell fate decisions. Critically, these developmental mechanisms are not reflected in mRNA abundance: the key biology resides in the spatial organization, abundance, and asymmetric localization of proteins within and between cells. The results show that early developmental patterning is associated with polarized localization of specific proteins and coordinated proteomic asymmetries across blastomeres, linking protein organization directly to lineage specification. These findings support a model in which cell fate in the mammalian embryo is not determined solely by stochastic transcriptional programs, but is strongly shaped by inherited and dynamically regulated protein states that establish developmental competence before overt differentiation: cell.com/cell/fulltext/S0092… Our results depended critically on single-cell proteomics analysis, on direct measurement of the molecular effectors that execute developmental decisions — capturing gradients, localization, stoichiometry, and post-transcriptional regulation. The future of developmental biology will depend increasingly on quantitative single-cell protein measurements capable of resolving the molecular architecture of cell fate determination: doi.org/10.1242/dev.201492