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

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 ?-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.

SUBMITTER: Wolfenson H 

PROVIDER: S-EPMC5296190 | biostudies-literature | 2016 Jan

REPOSITORIES: biostudies-literature