Membrane Tension Integrates Physical and Signaling Cues to Gate Cell Fate Transitions

Physical forces shape cell behavior, yet how they integrate with signaling to control fate and disease remains unclear. The alveolar epithelium is patterned by FGF signaling and mechanical stretch, but how these cues specify AT1 and AT2 cells is poorly understood. Here we show that cell membrane tension (CMT) is a conserved regulator of epithelial fate in mouse and human lungs. CMT drops before differentiation and is spatially patterned, defining where bipotent progenitors acquire AT1 or AT2 identity. Lower CMT enhances FGFR2 endocytosis and ERK signaling to drive AT2 differentiation and permits architectural remodeling that enables stretch-mediated YAP/TAZ nuclear entry for AT1 maturation. {beta}-catenin elevates CMT cell-intrinsically independent of its role in canonical WNT transcription, while embedding, osmotic compression, or fibroblast wrapping elevate CMT extrinsically. Combined intrinsic and extrinsic tension traps alveolar epithelial cells in a KRT8 transitional state seen in fibrotic lungs. Membrane tension thus integrates physical and molecular cues linking morphogenesis to fibrosis. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=160 HEIGHT=200 SRC="FIGDIR/small/708749v1_ufig1.gif" ALT="Figure 1"> View larger version (52K): org.highwire.dtl.DTLVardef@1a9c04forg.highwire.dtl.DTLVardef@190bee2org.highwire.dtl.DTLVardef@1e41664org.highwire.dtl.DTLVardef@17a3ec7_HPS_FORMAT_FIGEXP M_FIG C_FIG In BriefWe identify a conserved drop in cell membrane tension (CMT) that gates epithelial fate transitions across mouse and human lungs. In bipotent progenitors, reduced CMT promotes Alveolar Type 2 (AT2) fate via FGFR2 endocytosis and ERK signaling, as well as Alveolar Type 1 (AT1) fate by enabling architectural remodeling required for YAP/TAZ nuclear entry. We further show that intrinsic {beta}-catenin and extrinsic confinement cues, including mesenchymal contact, converge to elevate CMT, restricting differentiation and--in adult AT2s--inducing a KRT8 transitional state associated with fibrosis. HighlightsO_LICell membrane tension drops before differentiation and is required for AT1 and AT2 fate acquisition. C_LIO_LIReduced tension enhances FGFR2 endocytosis and ERK signaling to drive AT2 specification. C_LIO_LIReduced tension permits architectural remodeling and YAP/TAZ nuclear entry required for AT1 maturation. C_LIO_LIIntrinsic {beta}-catenin and extrinsic confinement elevate CMT to restrict differentiation and together strongly induce a KRT8 transitional state associated with fibrosis. C_LI