FGF signaling dynamics regulates epithelial patterning and morphogenesis

Summary Single cell assays revealed that growth factor signaling dynamics is actively sensed by a cell and ultimately controls cell fate. However, the effects of growth factor signaling dynamics at the tissue level have been unknown. We used mammary epithelial organoids, time-lapse imaging, fibroblast growth factor 2 (FGF2) variants of different stabilities, mathematical modeling, and perturbation analysis to study the role of FGF2 signaling dynamics in epithelial morphogenesis. We found that fluctuant and sustained FGF signaling dynamics induced distinct morphological and functional states of mammary epithelium through differential employment of intracellular effectors ERK and AKT. ERK activity domains determined epithelial branch size, while AKT activity drove epithelial stratification. Furthermore, FGF signaling dynamics affected epithelial tissue mechanoresponsiveness to extracellular matrix, thereby impinging upon branch elongation. Our study provides new insights into regulation of epithelial patterning and branching morphogenesis by FGF signaling dynamics and into downstream signaling effectors that regulate cellular outcomes.