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BP: Fachverband Biologische Physik

BP 7: Poster Session I

BP 7.17: Poster

Monday, March 9, 2026, 15:00–17:00, P5

Phosphorylation-induced softening of vimentin networks revealed by optical tweezers microrheology — •Yuzhen Feng, Shanay Zafari, and Sarah Köster — Institute for X-Ray Physics, University of Göttingen, Germany

Phosphorylation is a key post-translational modification regulating intermediate filament (IF) organization and cell mechanics. While phosphorylation-induced softening of single vimentin filaments has been reported, its impact on network-level mechanics remains unclear. Here, we employ optical tweezers-based active microrheology to quantify the mechanical properties of vimentin IF networks containing defined fractions of the phosphomimetic vimentin mutant S72E. Both unmodified and phosphomimetic vimentin networks exhibit a viscoelastic response with partial stress relaxation after deformation. Increasing the phosphomimetic content reduces the overall stiffness, indicating phosphorylation-induced softening at the network level. These findings extend the understanding of how biochemical regulation at the molecular level translates into mechanical remodeling of IF across scales from the single-filament to the network level.

Keywords: intermediate filaments; phosphorylation; optical tweezers; microrheology