Localized actin cortex perturbation generates cell-scale membrane tension gradients

Abstract

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.