Compression Generated by a 3D Supracellular Actomyosin Cortex Promotes Embryonic Stem Cell Colony Growth and Expression of Nanog and Oct4

Mechanical factors play critical roles in mammalian development. Here, we report that colony-growing mouse embryonic stem cells (mESCs) generate significant tension on the colony surface through the contraction of a three-dimensional supracellular actomyosin cortex (3D-SAC). Disruption of the 3D-SAC, whose organization is dependent on the Rho/Rho-associated kinase (ROCK) signals and E-cadherin, results in mESC colony destruction. Reciprocally, compression force, which is generated by the 3D-SAC, promotes colony growth and expression of Nanog and Oct4 in mESCs and blastocyst development of mouse embryos. These findings suggest that autonomous cell forces regulate embryonic stem cells fate determination and provide insight regarding the biomechanical regulation of embryonic development. Cells in an embryonic stem cell colony synergistically generate compression force by dynamically assembled cytoskeleton to facilitate the maintenance of colony morphology and pluripotency gene expression.