Vimentin protects the structural integrity of the nucleus and suppresses nuclear damage caused by large deformations

Mammalian cells frequently migrate through tight spaces during normal embryogenesis, wound healing, diapedesis or in pathological situations such as metastasis. The nucleus has recently emerged as an important factor in regulating 3D cell migration. At the onset of migratory behavior, cells often initiate the expression of vimentin, an intermediate filament protein which forms networks extending from a juxtanuclear cage to the cell periphery. However, the role of vimentin intermediate filaments (VIFs) in regulating nuclear shape and mechanics remains unknown. Here, we used wild type and vimentin-null mouse embryonic fibroblasts to show that VIFs regulate nuclear shape, motility, and the ability of cells to resist large deformations. The results show that loss of VIFs alters nuclear shape, reduces perinuclear stiffness, and enhances motility in 3D. These changes increase nuclear rupture and activation of DNA damage repair mechanisms, which are rescued by exogenous re-expression of vimentin. Our findings show that VIFs provide mechanical support to protect the nucleus and genome during migration.