Epidermal Wnt signaling regulates transcriptome heterogeneity and proliferative fate in neighboring cells

We performed single-cell mRNA-Seq on wild-type mouse keratinocytes co-cultured with keratinocytes in which beta-catenin was activated. We identified seven distinct cell states in cultures that had not been exposed to the beta-catenin stimulus. Using temporal single-cell analysis we reconstruct the cell fate changes induced by neighbor Wnt activation. Gene expression heterogeneity was reduced in neighboring cells and this effect was most dramatic for protein synthesis associated genes. The changes in gene expression were accompanied by a shift from a quiescent to a more proliferative stem cell state. By integrating imaging and reconstructed sequential gene expression changes during the state transition we identified transcription factors, including Smad4 and Bcl3, that were responsible for effecting the transition in a contact-dependent manner. Our data indicate that non cell autonomous Wnt/beta-catenin signaling decreases transcriptional heterogeneity and further our understanding of how epidermal Wnt signaling orchestrates regeneration and self-renewal.