Article
Softness, strength and self-repair in intermediate filament networks.
Department of Physiology, Institute for Medicine and Engineering, University of Pennsylvania, 1010 Vagelos Laboratories, 3340 Smith Walk, Philadelphia, PA 19104, USA.
Experimental Cell Research (impact factor:
3.58).
07/2007;
313(10):2228-35.
DOI:10.1016/j.yexcr.2007.04.025
pp.2228-35
Source: PubMed
-
Citations (0)
- Cited In (3)
-
Article: Properties of intermediate filament networks assembled from keratin 8 and 18 in the presence of Mg²⁺.
[show abstract] [hide abstract]
ABSTRACT: The mechanical properties of epithelial cells are modulated by structural changes in keratin intermediate filament networks. To investigate the relationship between network architecture and viscoelasticity, we assembled keratin filaments from recombinant keratin proteins 8 (K8) and 18 (K18) in the presence of divalent ions (Mg(2+)). We probed the viscoelastic modulus of the network by tracking the movement of microspheres embedded in the network during assembly, and studied the network architecture using scanning electron microscopy. Addition of Mg(2+) at physiological concentrations (<1 mM) resulted in networks whose structure was similar to that of keratin networks in epithelial cells. Moreover, the elastic moduli of networks assembled in vitro were found to be within the same magnitude as those measured in keratin networks of detergent-extracted epithelial cells. These findings suggest that Mg(2+)-induced filament cross-linking represents a valid model for studying the cytoskeletal mechanics of keratin networks.Biophysical Journal 07/2012; 103(2):195-201. · 3.65 Impact Factor -
Article: Divalent cations crosslink vimentin intermediate filament tail domains to regulate network mechanics.
[show abstract] [hide abstract]
ABSTRACT: Intermediate filament networks in the cytoplasm and nucleus are critical for the mechanical integrity of metazoan cells. However, the mechanism of crosslinking in these networks and the origins of their mechanical properties are not understood. Here, we study the elastic behavior of in vitro networks of the intermediate filament protein vimentin. Rheological experiments reveal that vimentin networks stiffen with increasing concentrations of Ca(2+) and Mg(2+), showing that divalent cations act as crosslinkers. We quantitatively describe the elastic response of vimentin networks over five decades of applied stress using a theory that treats the divalent cations as crosslinkers: at low stress, the behavior is entropic in origin, and increasing stress pulls out thermal fluctuations from single filaments, giving rise to a nonlinear response; at high stress, enthalpic stretching of individual filaments significantly modifies the nonlinearity. We investigate the elastic properties of networks formed by a series of protein variants with stepwise tail truncations and find that the last 11 amino acids of the C-terminal tail domain mediate crosslinking by divalent ions. We determined the single-filament persistence length, l(P) approximately 0.5 mum, and Young's modulus, Y approximately 9 MPa; both are consistent with literature values. Our results provide insight into a crosslinking mechanism for vimentin networks and suggest that divalent ions may help regulate the cytoskeletal structure and mechanical properties of cells.Journal of Molecular Biology 05/2010; 399(4):637-44. · 4.00 Impact Factor -
Conference Proceeding: Interactive cell injection simulation based on 3D biomechanical tensegrity model.
[show abstract] [hide abstract]
ABSTRACT: To facilitate training of biological cell injection operations, we are developing an interactive virtual environment to simulate needle insertion into biological cells. A key challenge of deformable simulation is to satisfy the conflicting requirements of real-time interactivity and physical realism. This paper presents methodologies for dynamic modeling, visual/haptic display and model validation of cell injection. We first investigate the challenging issues in the modeling of the bio-mechanical properties of living cells. We propose a dynamic model to simulate cell deformation and puncture. The developed approach is based on the assumptions that the mechanical response of living cells is mainly determined by the cytoskeleton and that the cytoskeleton is organised as a tensegrity structure including microfilaments, microtubules and intermediate filaments. Equivalent microtubules struts are represented with a linear mass-tensor finite element model and equivalent microfilaments and intermediate filaments with viscoelastic Kelvin-Voigt elements. The virtual environment has been implemented with both graphic and haptic interfaces.2008 IEEE/RSJ International Conference on Intelligent Robots and Systems, September 22-26, 2008, Acropolis Convention Center, Nice, France; 01/2008
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed.
The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual
current impact factor.
Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence
agreement may be applicable.
Keywords
bundles
cellular function
crossbridged neurofilaments
cytoskeletal filaments
elastic modulus
elastic properties
gels
IFs
IFs link
initial length
large deformations
large stresses
multivalent counterions
networks
polyelectrolyte properties
protein polymers
recent studies
small deformations
strains greater
viscoelastic characterization
