Nuclear integrity and genome stability in normal and HGPS cells. In normal cells, DNA damage arises from exposure to environmental fctors including reactive oxygen species, radiation or chemicals. This damage can be readily repaired by the DNA repair machinery. On the other hand, the incorporation of Progerin (brown lines) in the nuclear lamin network (green lines) alters nuclear morphology, resulting in defective nuclear processes for the maintenance of telomere length and DNA damage responses. In Progerin-expressing cells, accelerated aging ensues.