Autophagic degradation of nuclear components in mammalian cells

Autophagy is an evolutionally conserved intracellular mechanism for the degradation of organelles and proteins. Here we demonstrate the presence of perinuclear autophagosomes/autolysosomes containing nuclear components in nuclear envelopathies caused by mutations in the genes encoding A-type lamins (LMNA) and emerin (EMD). These autophagosomes/autolysosomes were sometimes bigger than nucleus. The autophagic nature is further supported by up-regulation of LC3-II in Lmna H222P/H222P fibroblasts. In addition, inhibition of autophagy led to the accumulation of nuclear abnormalities and reduced cell viability, highly suggesting a beneficial role of autophagy, at least in these cells. Similar giant autophagosomes/autolysosomes were seen even in wild-type cells, albeit rarely, implying that this "nucleophagy" is not confined to the diseased condition, but may be seen even in physiologic conditions to clean up nuclear wastes produced by nuclear damage.