SKM 2023 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 25: Cell Mechanics II

BP 25.2: Vortrag

Donnerstag, 30. März 2023, 15:15–15:30, BAR Schö

Mechanosensitive binding of filamins in the actin cytoskeleton of live cells — •Valentin Ruffine and Elisabeth Fischer-Friedrich — DFG Cluster of Excellence Physics of Life, Technische Universität Dresden, Dresden, Germany

Filamins A and B are cross-linkers of the actin cytoskeleton expressed in a wide range of human cell types. In particular, filamins are crucial in actin cytoskeleton interactions with the extracellular matrix and therefore are major molecular players in cartilage and bone development. Filamins form dimers which can bind and cross-link two actin filaments and thus contribute to the mechanical integrity of cytoskeletal structures such as the actin cortex. Myosin-generated contractile tension in the actin cortex is likely translated into a tensile force on the filamin-actin bonds in cross-linking filamins. Filamin binding to actin is transient with unbinding events after a characteristic bond lifetime. This enables large reorganizations of the cytoskeleton at longer timescales. However, tensile force in filamin-actin bonds may affect their unbinding kinetics. Here, we study the binding dynamics of filamins A and B to actin, in the cortex of mitotic HeLa cells. With a set-up combining a confocal and an atomic force microscope, we measure how changes in contractile tension in the actin cortex change filamin binding dynamics. Our results suggest a substantial increase of the lifetime of filamin-actin bonds under increased tensile force. This behavior is termed "catch-binding" and may act as a fast rescue mechanism that prevents rupture of filamin-containing actin cytoskeletal structures upon sudden tension increase.