Resumen
Within muscle fibers, desmin intermediate filaments (IFs) are major constituents of the extrasarcomeric cytoskeleton. However, their contribution to the mechanical properties of myocytes has remained elusive. We present an experimental approach to measure the extensibility and the tensile strength of in vitro reconstituted desmin IFs adsorbed to a solid support. The tip of an atomic force microscope (AFM) was used to push on single filaments perpendicular to the filament axis. The torque of the AFM cantilever was monitored during the pushing events to yield an estimate of the lateral force necessary to bend and stretch the filaments. Desmin IFs were stretched up to 3.4-fold with a maximum force of ∼3.5 nN. Fully stretched filaments exhibited a much smaller diameter than did native IFs, i.e., ∼3.5 nm compared to 12.6 nm, both by AFM and electron microscopy. Moreover, we combined the morphological and lateral force data to compute an average stress-strain curve for a single desmin filament. The main features were a pronounced strain-hardening regime above 50% extension and a tensile strength of at least 240 MPa. Because of these nonlinear tensile properties, desmin IFs may dissipate mechanical energy and serve as a physical link between successive sarcomeres during large deformation.
Idioma original | English |
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Páginas (desde-hasta) | 2790-2799 |
Número de páginas | 10 |
Publicación | Biophysical Journal |
Volumen | 94 |
N.º | 7 |
DOI | |
Estado | Published - abr. 2008 |
Nota bibliográfica
Funding Information:H.H acknowledges support from the German Research Foundation (DFG grant number HE 1853/4-3). U.A. and H.H. acknowledge the support by the European Commission (Contract LSHM-CT-2005-018690). L.K. was supported by a grant from the Swiss Society for Research on Muscular Diseases awarded to U.A. and Sergei Strelkov. This work was also supported by funds from the National Center of Competence in Research in Nanoscale Science (NCCR-Nano), an IF grant from the Swiss National Science Foundation, and funds from the Canton Basel-Stadt and the M. E. Müller Foundation of Switzerland, all awarded to U.A.
ASJC Scopus Subject Areas
- Biophysics