Description: Substrate, focal adhesion and actin filaments: A mechanical unit with a weak spot for mechanosensitive proteins

This title appears in the Scientific Report : 2010

Substrate, focal adhesion and actin filaments: A mechanical unit with a weak spot for mechanosensitive proteins

Mechanosensing is a vital prerequisite for dynamic remodeling of focal adhesions and cytoskeletal structures upon substrate deformation. For example, tissue formation, directed cell orientation or cell differentiation are regulated by such mechanosensing processes. Focal adhesions and the actin cyto...

Personal Name(s):	Kirchenbüchler, D.
	Born, S. / Kirchgeßner, N. / Houben, S. / Hoffmann, B. / Merkel, R.
Contributing Institute:	Biomechanik; IBN-4
Published in:	Journal of physics / Condensed matter, 22 (2010) S. 194109
Imprint:	Bristol IOP Publ. 2010
Physical Description:	194109
PubMed ID:	21386436
DOI:	10.1088/0953-8984/22/19/194109
Document Type:	Journal Article
Research Program:	BioSoft: Makromolekulare Systeme und biologische Informationsverarbeitung
Series Title:	Journal of Physics: Condensed Matter 22
Subject (ZB):	Actin Cytoskeleton: physiology Animals Cell Adhesion: physiology Cells, Cultured Fibroblasts: physiology Intracellular Signaling Peptides and Proteins: physiology Mechanotransduction, Cellular: physiology Rats Rats, Wistar Intracellular Signaling Peptides and Proteins J
	Publikationsportal JuSER

Please use the identifier: http://dx.doi.org/10.1088/0953-8984/22/19/194109 in citations.

Mechanosensing is a vital prerequisite for dynamic remodeling of focal adhesions and cytoskeletal structures upon substrate deformation. For example, tissue formation, directed cell orientation or cell differentiation are regulated by such mechanosensing processes. Focal adhesions and the actin cytoskeleton are believed to be involved in these processes, but where mechanosensing molecules are located and how elastic substrate, focal adhesions and the cytoskeleton couple with each other upon substrate deformation still remains obscure. To approach these questions we have developed a sensitive method to apply defined spatially decaying deformation fields to cells cultivated on ultrasoft elastic substrates and to accurately quantify the resulting displacements of the actin cytoskeleton, focal adhesions, as well as the substrate. Displacement fields were recorded in live cell microscopy by tracking either signals from fluorescent proteins or marker particles in the substrate. As model cell type we used myofibroblasts. These cells are characterized by highly stable adhesion and force generating structures but are still able to detect mechanical signals with high sensitivity. We found a rigid connection between substrate and focal adhesions. Furthermore, stress fibers were found to be barely extendable almost over their whole lengths. Plastic deformation took place only at the very ends of actin filaments close to focal adhesions. As a result, this area became elongated without extension of existing actin filaments by polymerization. Both ends of the stress fibers were mechanically coupled with detectable plastic deformations on either site. Interestingly, traction force dependent substrate deformation fields remained mostly unaffected even when stress fiber elongations were released. These data argue for a location of mechanosensing proteins at the ends of actin stress fibers and describe, except for these domains, the whole system to be relatively rigid for tensile strain with a mechanical coupling between the front and rear end of a cell.