Poster

Plectin mediates cell mechanics across time and length scales

Mathilde Lettinga^1,2, James Conboy², Gijsje Koenderink²

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We investigated the role of the crosslinking protein plectin in the mechanics of the cytoskeleton, the filamentous protein network that dominates cellular mechanics. Plectin is a giant cytoskeletal crosslinker protein of the plakin family that is expressed in mammalian cells of virtually all tissues. Its dysfunction is associated with various diseases, most prominently the skin disease Epidermolysis Bullosa Simplex. While previous work has uncovered the function of plectin as a scaffolding protein, as well as its cytoskeletal associations, studies on its role in cell mechanics are sparse. The few previously reported mechanical studies are based on adherent cells that are locally manipulated and measured. We aimed to elucidate the role of plectin in cells that undergo physiologically relevant large deformations. To this end, we used an Optics11 nanoindenter set-up akin to the commonly used AFM system, which allows for whole-cell compression and shear. We studied the role of plectin by comparing the rheological properties of wildtype mouse embryonic fibroblasts (MEFs) and plectin knockout MEFs. We found that plectin knockout cells are consistently softer than their wildtype counterparts, while their strain stiffening behaviour is similar. We observed that the cytoskeletal intermediate filament (IF) networks were structurally different, as IFs formed bundles in plectin knockout cells, while wildtype cells displayed a finer meshwork. These findings guide us towards understanding the role of crosslinking proteins in the bulk of the cell, and emphasise the importance of crosslinking between the different cytoskeletal networks.