FIGURE 1:

Local tensile stress applied to the nucleus in adherent cells can rupture the nuclear membranes. (A) Top: images show a representative MCF-10A nucleus expressing EGFP-NLS before application of stress (unstressed) and at the point of maximum deformation due to a local stress pulse of 10 kPa and duration of <1 s. The arrow indicates the location where the micropipette tip was attached to the nucleus. The outline overlay compares the outlines of the unstressed and deformed nucleus (right). Bottom: inverted time lapse fluorescent images of the nucleus probed above along with cytoplasm. The images show that the cytoplasmic intensity increases and the nuclear intensity decreases—the corresponding quantification of cytoplasmic and nuclear intensities (normalized to the corresponding initial intensity; stress pulse applied at time = 0) is shown in B—over the first several seconds, which indicates membrane rupture. Over longer times (∼30 min), both cytoplasmic and nuclear intensity are restored to levels before rupture indicating the nuclear membranes are repaired over time. (C) Images show cGAS-mCherry stably expressing MDA-MB-231 cell nucleus transfected with EGFP-NLS. Local tensile stress of 10 kPa (at the site indicated by rectangular box) causes the accumulation of cGAS cytoplasmic DNA binding protein near the site of stress application.