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Nat Cell Biol. 2016 Jan;18(1):33-42. doi: 10.1038/ncb3277. Epub 2015 Nov 30.

Tropomyosin controls sarcomere-like contractions for rigidity sensing and suppressing growth on soft matrices.

Author information

1
Department of Biological Sciences, Columbia University, New York, New York 10027, USA.
2
The Nanomedicine Center for Mechanobiology Directing the Immune Response, Columbia University, New York, New York 10027, USA.
3
Department of Chemical Engineering, Columbia University, New York, New York 10027, USA.
4
Department of Mechanical Engineering, Columbia University, New York, New York 10027, USA.
5
Institute for Bioengineering of Catalonia and University of Barcelona, Barcelona 08028, Spain.
6
Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore.

Abstract

Cells test the rigidity of the extracellular matrix by applying forces to it through integrin adhesions. Recent measurements show that these forces are applied by local micrometre-scale contractions, but how contraction force is regulated by rigidity is unknown. Here we performed high temporal- and spatial-resolution tracking of contractile forces by plating cells on sub-micrometre elastomeric pillars. We found that actomyosin-based sarcomere-like contractile units (CUs) simultaneously moved opposing pillars in net steps of ∼2.5 nm, independent of rigidity. What correlated with rigidity was the number of steps taken to reach a force level that activated recruitment of α-actinin to the CUs. When we removed actomyosin restriction by depleting tropomyosin 2.1, we observed larger steps and higher forces that resulted in aberrant rigidity sensing and growth of non-transformed cells on soft matrices. Thus, we conclude that tropomyosin 2.1 acts as a suppressor of growth on soft matrices by supporting proper rigidity sensing.

PMID:
26619148
PMCID:
PMC5296190
DOI:
10.1038/ncb3277
[Indexed for MEDLINE]
Free PMC Article

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