Single cell profiling technology now allows us to gain unprecedented insight into the complexities of gene expression within a developing tissue at the single cell level. Here (p. ), Steven Potter and colleagues provide a valuable resource comprising RNA-seq data on over 200 individual mouse kidney cells at three developmental stages. Two particularly notable findings point to a process of multilineage priming operating during the differentiation of kidney progenitors. First, the authors find that early progenitor cells may express markers of differentiated cells in an apparently stochastic manner. Second, in cells of the P4 renal vesicle, they observe expression of markers of multiple lineages in the same cell, implying that individual cells are capable of differentiating towards multiple fates, with markers of non-selected lineages being subsequently repressed as the cell differentiates. Such multilineage priming has been observed in other contexts, most notably the early embryo. Single cell expression analyses, such as that reported here, will allow us to more clearly understand the intricate interplay between gene activation and repression operating at the single cell level within a tissue to define cell fates.
