SKM 2023 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 28: Poster Session II
BP 28.32: Poster
Donnerstag, 30. März 2023, 18:00–20:00, P2/EG
Viscoelastic response of vimentin intermediate filament networks measured via optical tweezers-based active microrheology — •Kaan Ürgüp1, Anna V. Schepers2, and Sarah Köster1 — 1Institute for X-Ray Physics, Universität Göttingen, Germany — 2Rosalind Franklin Institute and Kennedy Institute of Rheumatology, University of Oxford, UK
The microscale mechanics of the intermediate filament (IF) cytoskeleton are relevant for many cellular processes. The properties of the IF network have been shown to influence cell motility, migration and organelle transport. On the molecular level, an IF monomer is composed of amino acids that lead to α-helical domains in the center, flanked by non-helical domains. Multiple monomers assemble laterally to unit-length-filaments and longitudinally to mature filaments. Vimentin is the most abundant IF protein in humans. Single vimentin filaments show a loading-rate dependent behavior, which can be attributed to the unfolding of α-helical structures into disordered structures and β-sheets when high strains are applied. What is unclear, however, is whether this nonlinear behavior is relevant in cellular vimentin networks. In this work, we measure strain and relaxation dynamics of in vitro vimentin networks via optical tweezers in the nonlinear regime. We use an active-passive calibration method based on the Onsager theorem. We measure the nonlinear response to different oscillation amplitudes, which correspond to different strains applied to the network. Our setup allows us to investigate whether the nonlinear behavior of the single filaments is preserved on the network scale.