The mechanical stability and deformability of the cell nucleus are crucial to many biological processes like migration, proliferation, and polarization. In vivo, the cell nucleus is frequently subjected to deformation on a variety of length and time scales, but current techniques for studying nuclear mechanics do not provide access to subnuclear deformation in live, functioning cells. Here we introduce vertical nanopillars as a new method for studying both nuclear deformability and the mechanical coupling between the cell membrane and the nucleus.  We have found that while the cell membrane conforms to the shape of the nanopillars, the nuclear envelope is much stiffer and thus deforms to a lesser degree. The extent of the nuclear deformation is determined by the geometry of the nanopillar array: it increases with the distance between nanopillars and the height of the nanopillars but decreases with increasing diameter.  We also found that the deformation of the nucleus is sensitive to the stiffness of the nucleus, as well as the cytoskeleton. When probed with nanopillar arrays of the same dimensions, 3T3 cells overexpressing lamin A showed dramatically less nuclear deformation than wild type 3T3 cells, indicating enhanced nuclear stiffness.  On the other hand, softer cells like neurons showed much greater nuclear deformation under the same conditions.  Finally, we found that, of the main cytoskeletal components, actin pulls the nucleus toward the membrane while intermediate filaments resist that action.  Nanostructures provide a new and exciting platform for studying cell and nuclear mechanics in length scales and contexts that are inaccessible to traditional techniques.

Vertical nanopillars for probing cell nuclear mechanics

248th National Meeting (2014)

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