Format

Send to

Choose Destination
PLoS One. 2015 May 15;10(5):e0126214. doi: 10.1371/journal.pone.0126214. eCollection 2015.

Cell elasticity is regulated by the tropomyosin isoform composition of the actin cytoskeleton.

Author information

1
Oncology Research Unit, School of Medical Sciences, UNSW Australia, Sydney, NSW 2052, Australia.
2
Oncology Research Unit, School of Medical Sciences, UNSW Australia, Sydney, NSW 2052, Australia; Biomedical Imaging facility, UNSW Australia, Sydney, NSW 2052, Australia.
3
Neurodegeneration and Repair Unit, School of Medical Sciences, UNSW Australia, Sydney NSW 2052, Australia.
4
Biomedical Imaging facility, UNSW Australia, Sydney, NSW 2052, Australia.
5
Neuromuscular and Regenerative Medicine Unit, School of Medical Sciences, UNSW Australia, Sydney, NSW 2052, Australia.

Abstract

The actin cytoskeleton is the primary polymer system within cells responsible for regulating cellular stiffness. While various actin binding proteins regulate the organization and dynamics of the actin cytoskeleton, the proteins responsible for regulating the mechanical properties of cells are still not fully understood. In the present study, we have addressed the significance of the actin associated protein, tropomyosin (Tpm), in influencing the mechanical properties of cells. Tpms belong to a multi-gene family that form a co-polymer with actin filaments and differentially regulate actin filament stability, function and organization. Tpm isoform expression is highly regulated and together with the ability to sort to specific intracellular sites, result in the generation of distinct Tpm isoform-containing actin filament populations. Nanomechanical measurements conducted with an Atomic Force Microscope using indentation in Peak Force Tapping in indentation/ramping mode, demonstrated that Tpm impacts on cell stiffness and the observed effect occurred in a Tpm isoform-specific manner. Quantitative analysis of the cellular filamentous actin (F-actin) pool conducted both biochemically and with the use of a linear detection algorithm to evaluate actin structures revealed that an altered F-actin pool does not absolutely predict changes in cell stiffness. Inhibition of non-muscle myosin II revealed that intracellular tension generated by myosin II is required for the observed increase in cell stiffness. Lastly, we show that the observed increase in cell stiffness is partially recapitulated in vivo as detected in epididymal fat pads isolated from a Tpm3.1 transgenic mouse line. Together these data are consistent with a role for Tpm in regulating cell stiffness via the generation of specific populations of Tpm isoform-containing actin filaments.

PMID:
25978408
PMCID:
PMC4433179
DOI:
10.1371/journal.pone.0126214
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Public Library of Science Icon for PubMed Central
Loading ...
Support Center