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

Haguy Wolfenson, Giovanni Meacci, Shuaimin Liu, Matthew Stachowiak, Thomas Iskratsch, Saba Ghassemi, Pere Roca-Cusachs, Ben O'Shaughnessy, James Hone, Michael Sheetz

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140 Citations (Scopus)
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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.
Original languageEnglish
JournalNature Cell Biology
Volume18
Early online date30 Nov 2015
DOIs
Publication statusPublished - 1 Jan 2016

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