Cytoskeletal disassembly by optogenetic control of RhoA signaling termination
Cellular morphodynamics require adaptive cytoskeletal remodeling, mediated by precisely coordinated activation and termination of RhoA GTPase signaling. RhoA activation is well-studied, but the kinetics and molecular basis of signaling termination remain poorly understood. We engineered an optogenetic toolbox on the single-component BcLOV4 platform for bidirectional control of RhoA activation (opto-GEF11) and termination (opto-DLC1). Prior studies have inferred GTPase inactivation kinetics indirectly, by tracking passive recovery from an activated state, but whether this reflects the kinetics of forward signaling termination remains unclear. Using opto-DLC1, we show that direct RhoA termination is an order of magnitude faster than passive disactivation, despite comparable signaling amplitude. Mechanistically, opto-DLC1 triggered rapid actin disassembly through cofilin disinhibition but drove YAP nuclear efflux at half the rate of opto-GEF11-induced nuclear influx. Together, these findings introduce a platform technology for controlling protein signaling termination, resolve RhoA activation and termination kinetics with sub-second precision, and reveal a mechanistic asymmetry between signaling activation and termination that enables cytoskeletal homeostasis.