Cytoplasmic anillin and Ect2 promote RhoA/myosin II-dependent confined migration and invasion.

Cell migration in mechanically confined environments is a crucial step of metastatic cancer progression. Nonetheless, the molecular components and processes mediating such behaviour are still not fully understood. Here we demonstrate that a pool of the scaffolding protein anillin and its cofactor Ect2, which are both predominantly nuclear proteins and critical mediators of cytokinesis, is present in the cytoplasm of multiple interphase cell types that promote confined cell migration. Confined migration in biomimetic microfluidic models triggers the actomyosin-binding-dependent recruitment of anillin to the plasma membrane at the poles of migrating cells in a manner that scales with microenvironmental stiffness and confinement. The guanine nucleotide exchange activity of Ect2 is required for its RhoA-GTPase-mediated activation of myosin II at the cell poles, enhancing invasion, bleb-based migration and extravasation. Confinement-induced nuclear envelope rupture further amplifies this process due to the release of further anillin and Ect2 into the cytoplasm. Overall, these results show how Ect2 and anillin cooperate to mediate RhoA/ROCK/myosin II-dependent mechanoadaptation and invasive cancer progression.