Dynamic force-induced nucleoporin stretch mechanomemory prolongs nuclear pore complex dilation and importin transport

How the nuclear pore complex (NPC) is dynamically regulated by mechanical stimuli is poorly understood. Herein, using FRET (fluorescence resonance energy transfer) spectroscopy and MINFLUX (MINimal fluorescence photon FLUXes) nanoscopy, we demonstrate that external local mechanical and global osmotic stresses to the surface of mammalian cells induced mechanomemory of nucleoporin (NUP) deformation. During and long after (∼30 min) local stress application via integrins or global hypo-osmotic stress, the FRET ratio of YFP-NUP62 (acceptor) to CFP-NUP88 (donor) decreased and remained low, suggesting that the distance between the two NUPs increased and the NUPs were stretched. Independent MINFLUX measurements of NPC strain memory following the same local mechanical or global osmotic stress mirrored the magnitude of NUP strain memory in the NPC observed via FRET. This cross-method validation supports the interpretation that the decreased FRET ratio primarily represents NUP stretching. Compared with stiff elastic and slow-relaxing viscoelastic substrates, soft elastic and fast-relaxing viscoelastic substrates extended the duration of mechanomemory of nucleoporin deformation to 60 min after stress cessation. Mechanomemory of NPC dilation prolonged translocation of importins α and β1 through the NPCs and translocation of importin β1-dependent histone deacetylase 3 into the nucleus. Our findings reveal the structural basis of dynamic force-induced nucleoporin mechanomemory in controlling NPC diameter. This, in turn, regulates nucleocytoplasmic transport-mediated mechanotransduction in living cells.