Mechanically-induced remodeling of the cell surface generates actin-rich protrusions resembling tunneling nanotubes

Cell surfaces are constantly exposed to mechanical stimuli, yet how they adapt over time and whether forces can trigger stable protrusion formation remains unclear. Here, we integrate optical tweezers-based tether extraction with real-time fluorescence microscopy and quantitative biophysical analysis to show that localized external forces dynamically remodel the cell surface. Ceasing the force immediately after tether formation leads to rapid recoil, whereas prolonged 5-minute force application induces a time-dependent increase in mechanical resistance and delays recoil, linking this adaptation to increased damping. The response is consistent with progressive recruitment of F-actin into tethers, accompanied by transitions in their force profiles from steady-state plateaus to recurrent spikes. The mechanism is conserved across cell types, relies on membrane-actomyosin integrity through a formin-driven, Arp2/3-independent pathway, and generates dynamically stable protrusions continuous with the cell surface. Together, our findings reveal a mechanically inducible mechanism that converts tethers into actin-rich protrusions resembling tunneling nanotubes, providing a potential route for targeted intercellular communication.