Intermediate Filament Networks

Fig. 1: Electron micrograph of reconstituted keratin intermediate filaments. Individual filaments (blue arrow) associate to thicker bundles. The red arrow indicates a branch point of two bundles.

Cells show a remarkable bandwidth of morphological and mechanical properties which allow them to fulfill the demands on dynamic and structural complexity of a living organism. The cytoskeleton, a biopolymer network constituted of microtubules, actin and intermediate filaments, is fundamental for these adaptive capabilities.

Eucaryotic cells lack the rigid cell walls of their plant counterparts. To yet maintain their structural integrity is one of the primary functions of intermediate filaments. In cooperation with cell-cell-junctions they represent an intercellular network of high resilience and flexibility.

Keratin as a Model System

The goal of this project is to investigate the properties of cytoskeletal composite networks using in vitro model systems of keratin intermediate filaments as well as actin and microtubules. Additionally the charakterisation of keratin as a potential material for bioengineering purposes is of great interest.

In order to thoroughly investigate these complex network it is necessary to employ a multilateral experimental approach:

  • Rheological measurements give insight into the mechanical properties of the networks.
  • With confocal microscope imaging one can illuminate microscopical properties of the network morphology.
  • Transmission electron microscopy (TEM) reveals details on filament assembly and structure.

The obtained informations show that keratin networks exhibit properties quite different from those of actin networks. One interesting feature of keratin filaments is e.g. their ability to intrinsically crosslink and bundle with each other (see fig. 1). This complementary nature might be of avail for the cell's versatile mechanical properties as well as for the use of keratin as material in bioengineering.