Intermediate filament assembly and network formation
The cytoskeleton provides mechanical stability for the cell. Actin filaments, microtubules, and intermediate filaments are the most important building blocks of these dense intracellular networks of biopolymers. While actin and microtubules are highly conserved in eukaryotic cells, each cell type is characterized by its unique combination of intermediate filaments. We study in vitro systems of intermediate filaments and aim to understand the assembly dynamics from smaller subunits to filaments and subsequent network formation as well as mechanical properties of individual filaments.
Susanne Bauch, Martha Brennich, Christian Dammann, Bernd Nöding
Intermediate filaments in microchannels of different width
Intermediate filament dynamics in living cells
Keratin is highly expressed in epithelial cells (cells on the surface of tissues) and forms thick cytoplasmic bundles. We study the structure and dynamics of these bundles of keratin intermediated filaments in living cells and aim to understand the influence of the cytoplasm and the interaction with other cytoskeletal proteins and molecular motors.
Jens Nolting, Jannick Langfahl, Britta Weinhausen
Intracellular keratin network
Mechanics of blood cells
Blood platelets (thrombocytes) are able to drastically rearrange their actin cytoskeleton and thereby change their shape on a time scale of only minutes. We aim to understand these dynamic processes and characterize the forces, which the cells impose on their environment. Furthermore, we study platelets on microstructured substrates and the resulting actin structure formation.
Sarah Schwarz, Rabea Sandmann
Movie of activating platelet on a glass surface (100x real time)
High resolution study of microfilaments - the hair cell as a model system
The actin cytoskeleton inside the stereocilia of hair cells in the inner ear is a sizable and organized bundle of parallel microfilaments. We use confocal and STED microscopy to better understand the molecular composition of these highly specialized actin-based structures during development. We also perform high-resolution measurements of the spacing of the actin filaments within individual stereocilia using space-resolved x-ray nano-diffraction to test whether the filament array is constantly maintained in one specific state or whether it changes depending on the physiological conditions of the cells.
Valeria Piazza
Actin cytoskeleton in a inner hair cell stereocilia bundle (adult mouse, width of picture 10 m)
Microfluidics and High-Resolution Imaging
We use high-resolution imaging methods, including optical microscopy (bright field, fluorescence, polarized light, phase contrast, and DIC), x-ray microscopy and scattering in combination with micro- and nanostructured surfaces and microfluidic flow chambers. Microfluidics allows us to study biological systems in physiological conditions and concomitantly under the influence of flow fields, gradients (e.g. of pH or specific reagents) or confinement. We develop methods to combine these specifically designed flow chambers with different imaging methods.
X-ray scattering and nanodiffraction
We use small angle x-ray scattering (SAXS) to study the macromolecular structure of cytoskeletal proteins in vitro. The combination with microfluidics allows us to perform time-resolved studies on dynamics in these structures induced by changes in the chemical composition of their environment. Furthermore, we apply x-ray nanodiffraction to investigate the structure of intracellular keratin bundles. This method enables us to achieve high-resolution structural information in combination with a non-destructive sample preparation.
