Localized actin cortex perturbation generates cell-scale membrane tension gradients

Membrane tension is a key mechanical regulator of cell signaling, morphology, and division. Whether cells can sustain spatial gradients in membrane tension, or whether such asymmetries are rapidly dissipated by long-range tension propagation, remains actively debated. Here, we use the tension-sensitive fluorescent probe FliptR to directly measure in-plane membrane tension before and after localized optogenetic activation of RhoA in mitotic HeLa cells. We find that localized RhoA activation generates a sustained, cell-scale membrane tension gradient, with tension elevated on the non-activated side. This gradient depends on an intact actin and microtubule cytoskeleton and is accompanied by polarized cytoskeletal remodeling: cortical f-actin enrichment at the activation site and asymmetric microtubule growth on the opposite side. Tether-force measurements reveal enhanced membrane–cortex adhesion at the activated side, with no corresponding increase in in-plane tension, reconciling an apparent discrepancy between prior studies. A coarse-grained membrane chemical potential accounts for gradient maintenance through spatially heterogeneous membrane–cortex coupling. Together, our findings demonstrate that cells can actively generate and sustain spatially patterned mechanical states through localized cytoskeletal signaling.